Cryogenic Liquids - Hazards

What are cryogenic liquids?

The vapours and gases released from cryogenic liquids also remain very cold. They often condense the moisture in air, creating a highly visible fog. In poorly insulated containers, some cryogenic liquids actually condense the surrounding air, forming a liquid air mixture. Cryogenic liquids are classified as "compressed gases" according to WHMIS criteria. Details of these criteria can be found in the Controlled Products Regulations.
Everyone who works with cryogenic liquids (also known as cryogens) must be aware of their hazards and know how to work safely with them.

What are the different types of cryogenic liquids?

Each cryogenic liquid has its own specific properties but most cryogenic liquids can be placed into one of three groups:

• Inert Gases: Inert gases do not react chemically to any great extent. They do not burn or support combustion. Examples of this group are nitrogen, helium, neon, argon and krypton.
• Flammable Gases: Some cryogenic liquids produce a gas that can burn in air. The most common examples are hydrogen, methane and liquefied natural gas.
• Oxygen: Many materials considered as non-combustible can burn in the presence of liquid oxygen. Organic materials can react explosively with liquid oxygen. The hazards and handling precautions of liquid oxygen must therefore be considered separately from other cryogenic liquids.

How are cryogenic liquids contained?

Cryogenic liquids are shipped and used in thermally insulated containers. These cryogenic liquid containers are specifically designed to withstand rapid temperature changes and extreme differences in temperature.

Liquid Dewar Flasks

Liquid dewar flasks are non-pressurized, vacuum-jacketed vessels, somewhat like a "Thermos bottle". They should have a loose fitting cap or plug that prevents air and moisture from entering, yet allows excess pressure to vent. Flasks containing helium, hydrogen and other low- boiling liquids have an outer vessel of liquid nitrogen for insulation.

Laboratory Liquid Dewar Flasks

Laboratory liquid dewars have wide-mouthed openings and do not have lids or covers. These small containers are primarily used in laboratories for temporary storage.

Liquid Cylinders

Liquid cylinders are pressurized containers specifically designed for cryogenic liquids. This type of container has valves for filling and dispensing the cryogenic liquid, and a pressure-control valve with a frangible (bursting) disk as backup protection. There are three major types of liquid cylinders which are designed for dispensing:

• liquid or gas
• only gas
• only liquid

What are the health hazards of cyrogenic liquids?

There are three groups of health hazards associated with cyrogenic liquids: extreme cold, asphyxiation, and toxicity.

Extreme Cold Hazard

Cryogenic liquids and their associated cold vapours and gases can produce effects on the skin similar to a thermal burn. Brief exposures that would not affect skin on the face or hands can damage delicate tissues such as the eyes. Prolonged exposure of the skin or contact with cold surfaces can cause frostbite. The skin appears waxy yellow. There is no initial pain, but there is intense pain when frozen tissue thaws.
Unprotected skin can stick to metal that is cooled by cryogenic liquids. The skin can then tear when pulled away. Even non-metallic materials are dangerous to touch at low temperatures. Prolonged breathing of extremely cold air may damage the lungs.

Asphyxiation Hazard

When cryogenic liquids form a gas, the gas is very cold and usually heavier than air. This cold, heavy gas does not disperse very well and can accumulate near the floor. Even if the gas is non-toxic, it displaces air. When there is not enough air or oxygen, asphyxiation and death can occur. Oxygen deficiency is a serious hazard in enclosed or confined spaces.
Small amounts of liquid can evaporate into very large volumes of gas. For example, one litre of liquid nitrogen vapourizes to 695 litres of nitrogen gas when warmed to room temperature (21°C).

Toxic Hazards

Each gas can cause specific health effects. For example, liquid carbon monoxide can release large quantities of carbon monoxide gas, which can cause death almost immediately. Refer to the material safety data sheet for information about the toxic hazards of a particular cryogen.

What are the flammability hazards of cyrogenic liquids?

Several types of situations exist that may result in a flammability hazard including: fire, oxygen-enriched air, liquid oxygen, and explosion due to rapid expansion.

Fire Hazard

Flammable gases such as hydrogen, methane, liquefied natural gas and carbon monoxide can burn or explode. Hydrogen is particularly hazardous. It forms flammable mixtures with air over a wide range of concentration (4 percent to 75 percent by volume). It is also very easily ignited.

Oxygen-Enriched Air

Liquid hydrogen and liquid helium are both so cold that they can liquefy the air they contact. For example, liquid air can condense on a surface cooled by liquid hydrogen or helium. Nitrogen evaporates more rapidly than oxygen from the liquid air. This action leaves behind a liquid air mixture which, when evaporated, gives a high concentration of oxygen. This oxygen-enriched air now presents all of the same hazards as oxygen.

Liquid Oxygen Hazard

Liquid oxygen contains 4,000 times more oxygen by volume than normal air. Materials that are usually considered non-combustible, (such as carbon and stainless steels, cast iron, aluminum, zinc and teflon (PTFE),) may burn in the presence of liquid oxygen. Many organic materials can react explosively, especially if a flammable mixture is produced. Clothing splashed or soaked with liquid oxygen can remain highly flammable for hours.

Explosion Due to Rapid Expansion

Without adequate venting or pressure-relief devices on the containers, enormous pressures can build up. The pressure can cause an explosion called a "boiling liquid expanding vapour explosion" (BLEVE). Unusual or accidental conditions such as an external fire, or a break in the vacuum which provides thermal insulation, may cause a very rapid pressure rise. The pressure relief valve may not be able to handle this increased pressure. Therefore, the containers must also have another backup device such as a frangible (bursting) disc.

How long should the skin or eyes be flushed with water in the event of a chemical exposure?

Most standard sources recommend that water rinsing/flushing following skin or eye contact with a chemical should continue for 15 or 20 minutes. However, all chemicals do not cause the same degree of effects (some are non-irritants while others can cause severe corrosive injury). At the present time, there is insufficient scientific evidence available to properly address the question of how long flushing should continue. However, it makes sense to tailor the duration of flushing to the known effects of the chemical or product, as follows:

• 5-minutes for non-irritants or mild irritants,
• 15-20 minutes for moderate to severe irritants and chemicals that cause acute toxicity if absorbed through the skin,
• 30 minutes for most corrosives, and
• 60 minutes for strong alkalis (e.g. sodium, potassium or calcium hydroxide).

It is very important that water flushing start immediately following skin or eye contact with a chemical. It is better if complete water flushing occurs on-site. However, moving the victim to an emergency care facility earlier may be necessary depending on the victim's condition (e.g. compromised airways, breathing or circulation) and/or the availability of a suitable water supply. If it is necessary to transport the victim before completing flushing on-site, flushing should continue during emergency transport, taking proper precautions to protect emergency services personnel.

Under what circumstances should oxygen be administered as a first aid measure?

In the past, emergency oxygen was commonly recommended as a first aid procedure for almost any chemical inhalation exposure. Later, concern was expressed that the administration of oxygen itself may be harmful if carried out improperly or in the wrong circumstances. In particular, there was concern that administering oxygen to victims with chronic obstructive lung diseases, such as chronic bronchitis or emphysema, could cause the victim to stop breathing. However, recent reviews have concluded that, during an emergency situation, the lack of oxygen is the most critical issue and there should be little concern over worsening the condition of victims with chronic obstructive pulmonary disease.
The presence of oxygen cylinders in the workplace can introduce additional hazards. For example, since oxygen supports combustion, the presence of oxygen cylinders could contribute to a fire hazard in the workplace. Also, since oxygen is stored under high pressure, the cylinder can behave like a missile if the valve breaks or the tank is punctured. Therefore, the risks and benefits of storing and maintaining an emergency oxygen supply in the workplace must be weighed.
There are some situations where the benefits of emergency oxygen outweigh the potential risks associated with maintaining and storing oxygen cylinders in the workplace. Emergency oxygen may be beneficial following exposure to chemicals that interfere with the body getting the necessary levels of oxygen to sustain life and health, including chemicals that:

• Displace oxygen in the air, reducing the amount of oxygen available for breathing (e.g., helium, argon, methane, carbon dioxide or nitrogen).
• Reduce the ability of blood to transport oxygen (e.g., carbon monoxide poisoning, or methemoglobinemia (presence of an oxidized form of hemoglobin in the blood that does not transport oxygen)).
• Compromise the use of oxygen by body tissue, as with cyanide or hydrogen sulfide toxicity.
• Interfere with the ability of oxygen to cross through the lungs to the blood stream, as occurs with pulmonary edema, a potentially fatal accumulation of fluid in the lungs. Ammonia, phosgene and chlorine are examples of chemicals that can cause pulmonary edema.
• Provoke a severe asthma attack (e.g., toluene diisocyanate).

Additional training of first aid providers is required since basic first aid training courses do not include oxygen administration. First aid providers must be familiar with the laws that govern the use of oxygen administration in their workplace.

When should vomiting be induced following ingestion of a chemical?

Vomiting should NOT be induced following ingestion of a chemical in an occupational setting unless advised by a Poison Centre or doctor. Some of the arguments against inducing vomiting are:

• The amount of chemical accidentally ingested by an adult is generally estimated to be very small (14-21 mL or about 0.5-0.75 oz).
• There is no conclusive evidence that victims of chemical ingestion who do have their stomachs emptied have more successful outcomes than victims who do not.
• There can be significant risks associated with inducing vomiting especially in emergency situations.
• There does not seem to be a reliable and safe first aid procedure for inducing vomiting in adults.
• Medical attention is usually available quite quickly in most situations.

In the event of a chemical ingestion, the best course of action is to call your local Poison Control Centre or a doctor and follow their advice. They will ask you specific questions, such as the name of the product ingested, the amount ingested and the condition of the victim. This information will assist them in determining the best course of action.

Should water or milk be given to dilute a chemical that has been ingested?

Much of what we know about the benefits of diluting an ingested chemical with water or milk is based on in vitro (test tube) and ex vivo (using harvested rat esophagi) studies.
Based on their evaluation of the evidence for dilution with milk or water, the American Heart Association and American Red Cross recommend that people should not take anything by mouth for an ingested poison unless specifically told to do so by a doctor or the poison control centre.

How do I know which antidote to have available for the chemicals in my workplace?

It is a common misperception that antidotes are available for most chemical poisonings. True antidotes are the exception rather than the rule.
Activated charcoal is sometimes considered to be an antidote. Activated charcoal works by binding the chemical in the stomach so it cannot be absorbed through the stomach. According to the American Academy of Clinical Toxicology and the European Association of Poisons Centres "the administration of activated charcoal may be considered if a patient has ingested a potentially toxic amount of a poison (which is known to be adsorbed to charcoal) up to 1 hour previously...". In general, the administration of activated charcoal is NOT considered a first aid procedure. Activated charcoal may be administered in the emergency department or under medical supervision.
Some chemical classes do have true antidotes - cyanides and organophosphate pesticides are good examples. You can determine which chemicals used in your workplace have antidotes by consulting with a doctor with certification in medical toxicology or occupational medicine, or the manufacturer/supplier of your product. These specialists can advise you on situations where it may be appropriate to store an antidote onsite. Special training of first aid providers will be required.

How do I know which first aid procedures to follow for chemicals used in my workplace?

In order to know what first aid procedures to follow, it is essential that you know what chemicals are present in your workplace. Consult your chemical inventory and the First Aid Measures Section on the Material Safety Data Sheets (MSDSs). Create a list of chemicals, their properties and their corresponding first aid requirements. Be sure that the emergency first aid providers in your workplace have the appropriate training and authority (if necessary) to deal with the types of chemicals used at your workplace.
Finally, make sure your local hospital is aware of any chemicals on your site that may require special first aid procedures, antidotes or medical follow-up.

What are basic safe practices when working with compressed gases?

Following these basic general safe practices will help protect you from the hazards of compressed gases:

• Read the MSDSs and labels for all of the materials you work with.
• Know all of the hazards (fire/explosion, health, chemical reactivity, corrosivity, pressure) of the materials you work with.
• Know which of the materials you work with are compressed gases and check the label, not the cylinder colour, to identify the gas.
• Store compressed gas cylinders in cool, dry, well-ventilated areas, away from incompatible materials and ignition sources. Ensure that the storage temperature does not exceed 52°C (125°F).
• Store, handle and use compressed gas cylinders securely fastened in place in the upright position. Never roll, drag, or drop cylinders or permit them to strike each other.
• Move cylinders in handcarts or other devices designed for moving cylinders.
• Leave the cylinder valve protection cap in place until the cylinder is secured and ready for use.
• Discharge compressed gases safely using devices, such as pressure regulators, approved for the particular gas.
• Never force connections or use homemade adaptors.
• Ensure that equipment is compatible with cylinder pressure and contents.
• Carefully check all cylinder-to-equipment connections before use and periodically during use, to be sure they are tight, clean, in good condition and not leaking.
• Carefully open all valves, slowly, pointed away from you and others, using the proper tools.
• Close all valves when cylinders are not in use.
• Never tamper with safety devices in cylinders, valves or equipment.
• Do not allow flames to contact cylinders and do not strike an electric arc on cylinders.
• Always use cylinders in cool well-ventilated areas.
• Handle "empty" cylinders safely: leave a slight positive pressure in them, close cylinder valves, disassemble equipment properly, replace cylinder valve protection caps, mark cylinders "empty" or "MT," and store them separately from full cylinders.
• Wear the proper personal protective equipment for each of the jobs you do.
• Know how to handle emergencies such as fires, leaks or personal injury.
• Follow the health and safety rules that apply to your job.

Compressed Gases - How Do I Work Safely with

What are cylinders and fittings?

Compressed gases are stored in heavy-walled metal cylinders designed, produced and tested for use with compressed gases. Cylinders are made in a wide variety of sizes and shapes. They range from small lecture bottles, often used for demonstration purposes, to large cylinders over 3 metres long. Cylinders for transportation must meet CSA standard CAN/CSA-B339 "Cylinders, Spheres and Tubes for the Transportation of Dangerous Goods". This standard covers requirements for the manufacturing, inspection, testing, marking, requalification, reheat treatment, repair, and rebuilding of cylinders, spheres, and tubes (containers) for the transportation of dangerous goods. In addition, it includes the requirements for the qualification of new designs and registration requirements. You should also consult CAN/CSA-B340 "Selection and Use of Cylinders, Spheres, Tubes, and Other Containers for the Transportation of Dangerous Goods, Class 2".
Cylinders that meet these criteria are often referred to as "TC approved" cylinders. Cylinders are permanently marked, typically on the shoulder or the top surface of its neck.
Usually, cylinders must be retested or inspected every five or ten years. The date of each test must be stamped on the cylinder.

Cylinder Valves and Connections

Compressed gas cylinders must be connected only to regulators and equipment designed for the gas in the cylinder. Since connecting the wrong equipment can be dangerous, a number of different standard cylinder valve outlets are available for different classes of gas. For example, these standard connections prevent the valve connection for a flammable gas from fitting the connections for an incompatible gas, such as an oxidizing gas.
Most compressed gas cylinders have valve caps or some other method of protecting the valve from damage during handling and transportation. A dust cap may be placed over the valve outlet itself to help keep it clean.

What are cylinder safety devices?

Most cylinders have one or more safety-relief devices. These devices can prevent rupture of the cylinder if internal pressure builds up to levels exceeding design limits. Pressure can become dangerously high if a cylinder is exposed to fire or heat, including high storage temperatures.
There are three types of safety-relief devices. Each relieves excessive gas pressures in a different way:

• Safety- or Pressure-Relief Valves: These valves are usually a part of the cylinder. They are normally held closed by a spring. The force holding the valve closed is set according to the type of gas in the cylinder. The valve opens if the cylinder pressure exceeds the set safety limit. Gas is released until the cylinder pressure drops back to the safety limit. The valve then closes and retains the remaining gas in the cylinder.
• Rupture Discs (also known as frangible or bursting discs): These discs are usually made from metal. They burst or rupture at a certain pressure, releasing the gas in the cylinder. The bursting pressure is designed so that the disc ruptures before the cylinder test pressure is reached. These devices cannot be reclosed, so the entire contents of the cylinder are released.
• Fusible Plugs (also called fuse or melt plugs): Temperature, not pressure, activates fusible plugs. These safety devices are used where heat could initiate an explosive chemical reaction. A pressure-relief valve or rupture disc acts too slowly and too late to prevent rupture of the cylinder if an explosive reaction has already begun. The fusible plug releases the gas before the hazardous reaction can begin. Fusible plugs are made of metals that melt at low temperatures. For example, acetylene cylinders have a fusible plug which melts at about 100°C (212°F). This temperature is safely below the temperature at which hazardous polymerization may occur.

Not all compressed gas cylinders have safety devices. Some gases are so toxic that their release through a safety device would be hazardous. Cylinders for these gases are built to withstand higher pressures than normal cylinders. When these "toxic gas" cylinders are involved in a fire, the area must be evacuated.

Why should I use substitution as a method of controlling exposure to compressed gases?

Substitution can be the best way to avoid or reduce a hazard. But it is not always easy or even possible to find a less hazardous substitute for a particular compressed gas used for a certain job. Speak to the chemical supplier to find out if safer substitutes are available. For example, in some cases, methylacetylene-propadiene (MAPP) gas, propylene, propane or mixtures of liquefied petroleum gas can be substituted for acetylene as fuel gases for cutting, welding and brazing. These gases are more stable and can be stored in normal cylinders. Their flammable limits are much narrower than those of acetylene (e.g., 3.4 to 10.8 percent for MAPP versus 2.5 to 82 percent for acetylene), so they represent a reduced fire hazard.
Obtain MSDSs for all possible substitutes. Find out about all of the hazards (health, fire, corrosivity, chemical reactivity) of these materials before making any changes.
Sometimes, process changes or modifications can reduce a material's hazards. For example, many cylinders of the same gas may be used in different areas of a workplace. Installing fixed pipelines connected to a central gas supply in a safe area can often reduce the hazard. It can also reduce the need for many sets of portable equipment supplied through flexible hoses. Similarly, ordering cylinders equipped with flow limiting restrictors can minimize the hazards of a sudden failure of a process gas line.
Choose the least hazardous material and process that can do the job effectively and safely. Then learn how to work safely with them.

Why is proper ventilation important?

Well-designed and well-maintained ventilation systems remove gases from the workplace and reduce their hazards.
The amount and type of ventilation needed depends on such things as the type of job, the kind and amount of materials used, and the size and layout of the work area.
Assess the specific ways your workplace stores, handles, uses and disposes of its compressed gases. An assessment can reveal if existing ventilation controls and other hazard control methods are adequate. Some workplaces may need a complete system of hoods and ducts to provide acceptable ventilation. Others may require a single, well-placed exhaust fan. Storage facilities for particularly hazardous materials such as chlorine, may require an additional emergency ventilation system, or continuous monitoring with appropriate alarms. Other workplaces using small amounts of inert gases may require no special ventilation system.
Make sure ventilation systems are designed and built so that they do not result in an unintended hazard. Ensure that hoods, ducts, air cleaners and fan are made from materials compatible with the gas used. Systems may require explosion-proof and corrosion-resistant equipment. Separate ventilation systems may be needed for some compressed gases to keep them away from systems exhausting incompatible substances.

How do I store compressed gas cylinders?

Store compressed gas cylinders in compliance with the occupational health and safety regulations and fire and building codes applying to your workplace. These laws may specify the permissible kinds of storage areas and the construction of these storage areas. They may also specify the kinds and amounts of different gases that can be stored in each safe storage area.

What should I do when I receive cylinders?

Inspect all incoming cylinders before storing to ensure they are undamaged and properly labelled. Do not accept delivery of defective cylinders. Be sure they are not giving off odours, visible fumes or hissing sounds. Check that the cylinder was last tested within the required time (usually 5 or 10 years, but some containers may be as low as 3 years or as long as 12 years).
Also check that the cylinder labels are intact and that they match other identifying markings on the cylinder. Do not rely on cylinder colour to identify the gas. Different suppliers may use different colours for cylinders of the same gas. In addition, colours appear different under artificial lights and some people are colour blind. Gases that cannot be clearly identified should not be used.
Call compressed gases by the name on the supplier label. This reduces confusion, promotes recognition of the hazards involved and precautions to take, and can prevent accidental use of the wrong gas. If oxygen is called "air," someone who wants air to run a tool may use oxygen with possible serious results. Leave the valve cap securely in place until the cylinder is to be used. Inspect the cylinder valve by looking through the ports in the valve cap. Do not accept dirty, rusted or otherwise damaged valves and fixtures.

How do I transport or move cylinders?

Always transport cylinders with valve caps or other valve protection in place. Pulling cylinders by their valve caps, rolling them on their sides or dragging or sliding them can cause damage. Rolling cylinders on their bottom edge ("milk churning") may be acceptable for short distances. Never lift cylinders with magnets or chain or wire rope slings. Transport cylinders on specially built hand carts or trolleys or other devices designed for this. All transport devices should have some way of securing cylinders to prevent them from falling.

What should I know about the compressed gas storage area?

Store compressed gas cylinders separately, away from processing and handling areas, and from incompatible materials. Separate storage can minimize personal injury and damage in case of fires, spills or leaks. Many compressed gases can undergo dangerous reactions if they come in contact with incompatible materials (gases, liquids or solids), so store them apart from each other. For example, store oxidizing gases at least 6 metres (20 feet) away from fuel gases or other combustible materials, or separate them with an approved fire wall. Check the reactivity information and storage requirements sections of the MSDS for details about which materials are incompatible with a particular compressed gas. The National Fire Code addresses requirements for segregation of different gases in storage.
If compressed gas cylinders are stored outside, use a well-drained, securely fenced area. Keep them on a raised concrete pad or non-combustible rack. Protect cylinders from the weather and do not allow them to stand directly on wet soil as this can cause corrosion.
Indoor storage areas must have walls, floors and fittings made of suitable materials. For example, use non-combustible building materials in storage areas for oxidizing gas and corrosion-resistant materials in storage areas for corrosive gas. Make sure floors are level and protect cylinders from dampness. Avoid overcrowding in storage areas or storing cylinders in out-of-the-way locations.
Always chain or securely restrain cylinders in an upright position to a wall, rack or other solid structure wherever they are stored, handled or used. Securing each cylinder individually is best. Stacking of groups of cylinders together offers some protection, but if this is done improperly, the entire group or individual cylinders could fall.
Store compressed gas cylinders in areas which are:

• Well-ventilated and dry.
• Fire-resistant and supplied with suitable firefighting equipment including sprinklers, where appropriate.
• Away from electrical circuits and ignition sources such as sparks, flames or hot surfaces.
• Accessible at all times, but away from elevators, staircases or main traffic routes where cylinders may be dangerous obstacles.
• Labelled with suitable warning signs.

Always store full cylinders separately from empty cylinders.

What should I know about compressed gas storage temperatures?

Store compressed gas cylinders in dry, cool areas, out of direct sunlight and away from steam pipes, boilers or other heat sources.
Follow the gas supplier's recommendations for storage and use temperatures. To prevent excessive pressure buildup, never expose cylinders to temperatures above 52°C (125°F). Do not subject them to temperatures below -29°C (-20°F), unless they are designed for this. Cylinders that become frozen to a surface can be freed by using warm water (less than 52°C). Never apply direct heat to a cylinder.

What are some general precautions about compressed gas storage?

At all times:

• Allow only trained, authorized people into storage areas.
• Keep the amount of compressed gases in storage as small as possible.
• Inspect storage areas regularly for any deficiencies such as damaged or leaking cylinders and poor housekeeping.
• Correct all deficiencies as soon as possible.

What should I know about using and discharging compressed gas cylinders?

General precautions

When moving cylinders, securely fasten them to a suitable cylinder transporting device. At the site, chain or otherwise secure the cylinder in place. Remove the valve cap only after the cylinder has been safely installed then check the cylinder valve and fixture. Remove any dirt or rust. Grit, dirt, oil or dirty water can cause gas leaks if they get into the cylinder valve or gas connection.
Never open a damaged valve. Contact your gas supplier for advice.
There are four standard types of cylinder valve outlets to prevent interchanges of gas handling equipment between incompatible gases. Use only the proper equipment for discharging a particular gas from its cylinder. Never use homemade adaptors or force connections between the cylinder valve outlet and gas handling equipment.
Whether a compressed gas is a liquefied, non-liquefied or dissolved gas, the gas supplier can give the best advice on the most suitable gas discharge equipment and the safest way to use it for a specific job.
In general, do not lubricate any cylinder valves, fittings, or regulator threads, or apply jointing compounds and tape. Use only lubricants and sealants recommended by the gas supplier.
Cylinders stored in cold areas may have frozen valves. Use only warm water to thaw the valve or bring the cylinder into a warm area and allow it to thaw at room temperature.
Use only recommended keys or handwheels to open valves. Never use longer keys or modify keys to increase their leverage. Avoid using even the correct key if it is badly worn. Do not use pipe wrenches or similar tools on handwheels. Any of these practices could easily damage the valve seat or spindle.
Always open valves on all gas discharge equipment slowly. Rapid opening of valves results in rapid compression of the gas in the high-pressure passages leading to the seats. The rapid compression can lead to temperatures high enough to burn out the regulator and valve seats. Many accidents involving oxidizing gases result from burned out regulator and valve seats, usually caused by opening valves too quickly.
Do not use excessive force when opening cylinder valves--use no more than three quarters of a turn if possible. If a problem develops, the valve can then be closed quickly. Leave keys on cylinders when valves are open so the valve can be closed quickly in an emergency. Some cylinder valves, such as oxygen valves, have double seating. These valves should be fully opened, otherwise they may leak.
Do not use excessive force when opening or closing a cylinder valve. When closing, turn it just enough to stop the gas flow completely. Never force the valve shut.
Close cylinder valves when the cylinder is not actually in use. Do not stop the gas flow from a cylinder by just backing off on the regulator. Regulators can develop seat leaks, allowing pressure to build up in equipment attached to the regulator. Also if the cylinder valve is left open, foreign matter can enter the cylinder if the cylinder pressure drops lower than the pressure in attached equipment. Close the cylinder valve first and then close the regulator.

Liquefied Gases

Manual valves are normally used on cylinders containing liquefied gases. Special liquid flow regulators are also available. If it is necessary to remove liquid as well as gas from a cylinder, discuss this with the gas supplier before ordering. Some liquefied gas cylinders have eductor tubes which allow the liquid to be withdrawn from the cylinder. The supplier can provide suitable cylinders and special instructions.
Do not remove gas rapidly. The pressure in the cylinder could drop below the required level. If this happens, or if rapid gas removal is needed, follow the gas supplier's advice.

Non-Liquefied and Dissolved Gases

Use automatic pressure regulators to reduce gas pressure from the high levels in the cylinder to safe levels for a particular job.
There are two basic types of automatic pressure regulators: single-stage, and double- or two-stage. Generally, two-stage regulators deliver a more constant pressure under more precise conditions than single-stage regulators. Sometimes, manual flow controls are used on non-liquefied gases. Fine flow control can be obtained, but an operator must be present at all times. Manual flow controls do not automatically adjust to pressure buildups in blocked systems.

What are some guidelines for safe handling and use?

Use the smallest practical cylinder size for a particular job. Do not keep cylinders longer than the supplier recommends. Compressed gas cylinders are mainly shipping containers. They are built to be as light as possible while remaining safe and durable. Do not drop cylinders or otherwise allow them to strike each other. Rough handling, including using cylinders as hammers or as rollers to move equipment, can seriously damage them.
Do not strike an electric arc on a cylinder. Arc burns can make the metal brittle and weaken the cylinder.
Never tamper with cylinders in any way. Do not repaint them, change markings or identification, or interfere with valve threads or safety devices.
Apart from the fact that it is illegal, it can be dangerous for non-specialists to refill cylinders or to change their contents. Explosions, cylinder contamination or corrosion can result.

What should I know about equipment associated with compressed gases?

All equipment used with compressed gases must be clean, properly designed and maintained, and made from materials compatible with the gas used. For example, acetylene forms explosive compounds in contact with copper, silver and mercury or their alloys, including bronze or brass containing more than 65 percent copper. Ammonia attacks brass and can react with mercury to form an explosive compound. Do not use mercury pressure gauges in ammonia systems.
In general, avoid pressurizing ordinary glass equipment. Use specially designed glass equipment and protective devices. Where cylinders are connected to a manifold or header, make sure specialists properly design and install the system. Use effective flashback arrestors on acetylene and other flammable gas systems.
Always follow the correct procedures for assembling and disassembling compressed gas equipment. Check that all the connections are clean and do not leak. Check for leaks, using the gas suppliers recommended method, after assembling and before starting to use equipment. Never use old clips or twisted wire for hose connections. If a hose works loose and flails around, serious injury could result. Poor hose connections are a common cause of accidents.
Acetylene under pressure can explode. Never use acetylene outside of the cylinder at pressures over 103 kPa (15 psig) unless you take special precautions. If an acetylene cylinder has been accidentally left on its side, set it upright for at least an hour before use. Otherwise, it will emit a burst of solvent instead of gas when the valve is opened.
Corrosive gases can "freeze" the valve stem, making it hard to open the valve. This results from the gas corroding the valve metal. Minimize "freezing" by rotating the valve stem at least once a day while the cylinder is in use. Also, flush the regulator or manual control valve with dry nitrogen or dry air as soon as possible after use.

Are there special precautions for oxidizing gases?

Special cleaning procedures (equivalent to oxygen service) are required for all equipment to be used with oxidizing gases. There are several ways to do this. Contact your gas supplier for the best methods for specific systems.
Do not oil or grease any equipment that may contact oxidizing gases. Keep greasy hands, rags and gloves away from any part of the cylinder and fittings. Normal body oils are usually not hazardous, although it is a good practice never to touch any surface that may contact an oxidizing gas. Use lubricants and connection or joint sealants recommended by the gas supplier.
Only use oxygen for its intended purpose. Never use it to purge pipelines or to provide ventilation. Freshening the air with oxygen may make people more comfortable, but it also enriches the oxygen content in the area which can quickly create a major fire hazard. Serious accidents have occurred when oxygen was used to run tools designed for compressed air. High oxygen pressure can cause the lubricant in the tool to explode.

Can I use compressed gases in confined spaces?

Always comply with applicable occupational health and safety laws when working in a confined space. When using compressed gases, including inert gases, in a confined space, be sure to check that all equipment connections are leak-tight. Remove cylinders or connected equipment that are not in use from confined spaces, even during short breaks. Check the air for oxygen levels (high and low). Also check for any possible toxic, corrosive or flammable gases before entering confined spaces and during prolonged work periods. Never work alone.

How do I handle and store "empty" cylinders?

Non-Liquefied and Dissolved Gases

The amount of material remaining in a non-liquefied or dissolved gas (acetylene) cylinder is directly proportional to the cylinder pressure gauge reading. As the gas is used, the reading on the cylinder pressure gauge drops. When the cylinder pressure gauge reads zero, the cylinder is not really empty. The cylinder still contains gas at atmospheric pressure. Keep a slight positive pressure in the cylinder. Consider it "empty" when the cylinder pressure gauge reads about 172 kPa (25 psig) or when the cylinder will not deliver at least 172 kPa to the outlet pressure gauge.

Liquefied Gases

The pressure in liquefied gas cylinders remains constant at a given temperature as long as any liquid remains in the cylinder. The only way to know how much material remains in a liquefied gas cylinder is to weigh the cylinder. The empty (tare) weight of the cylinder is stamped on its neck or valve stem. Record the net weight of the cylinder contents on a card attached to it. As with non-liquefied and dissolved gases, never empty the cylinder completely. Keep a small amount of material in the cylinder to maintain a slight positive pressure.

What are general precautions for "empty" cylinders?

Keeping a positive pressure in an "empty" compressed gas cylinder helps to prevent back flow or suck back. This back flow is the drawing-back into the cylinder of contaminants or moist air from a higher pressure system or the atmosphere.
Keep the valves on all "empty" cylinders closed. This practice maintains a positive pressure in them. "Empty" cylinders with open valves can "breathe". Temperature increases or drops in atmospheric pressure can force gas out of the open valve of an empty cylinder. This release could result in hazardous conditions depending on the gas and how much is forced out. Temperature drops or increases in atmospheric pressure can cause air to be drawn in through the open valve. Air could cause a serious contamination and corrosion problem inside the cylinder. When a compressed gas cylinder is "empty," handle it as though it is full since it does contain gas.
Always:

• Close the cylinder valve before removing the gas discharge equipment.
• Clearly mark or label the cylinder "empty" or "MT."
• Place the cylinder in a storage area separate from that used for full cylinders.
• Keep incompatible materials away from the cylinder.
• Notify the gas supplier if the cylinder or any part of it is damaged or defective, contaminated, or may have been exposed to a possibly hazardous condition such as a fire or electric arc.

Take care when scrapping unserviceable cylinders. Before scrapping, first destroy the cylinder as a pressure vessel. Contact the gas supplier for advice on disposing of unserviceable cylinders.

What are some good housekeeping rules for working with compressed gas cylinders?

Maintain good housekeeping at all times in the workplace:

• Never hang clothes or equipment over a compressed gas cylinder.*
• Never use oxygen or even compressed air to remove dust from clothing or equipment.
• Promptly remove combustible wastes including wood, paper or rags, from the work area.
• Properly and promptly dispose of "empty" or unlabelled cylinders.

*Note: Hanging things over a cylinder makes it harder to operate the valve. In addition, clothing may become saturated with a hazardous gas. Clothing saturated with either an oxidizing gas or flammable gas will catch on fire easily and burn intensely. Hang clothes that are even partly saturated with an oxidizing gas or fuel gas in a well-ventilated area for at least 15 minutes to remove trapped gas.

Why is personal cleanliness important?

Personal cleanliness helps protect people working with hazardous materials:

• Wash hands before eating, drinking, smoking or going to the toilet.
• Remove contaminated clothing since it may be a severe fire or health hazard.
• Do not wear or carry items contaminated with oxidizing or flammable gases into areas having ignition sources or where smoking is allowed.
• Store food and tobacco products in uncontaminated areas.
• Clean yourself thoroughly at the end of the workday.

Why is equipment maintenance important?

Regular workplace inspections can help to spot situations where compressed gases are stored, handled, or used in potentially hazardous ways.
Regular inspection of equipment can provide a warning of potential hazards:

• Examine regulators, pressure relief valves and cylinder connections.
• Ensure that cylinders are free of corrosion, leakage, pitting, dents or gouges.
• Regular equipment maintenance can prevent hazardous conditions in the workplace.

Ensure that maintenance personnel:

• Know the possible hazards of the materials they may encounter and any special procedures and precautions before they begin to work.
• Carry out repairs to equipment properly, using equipment suitable for the contents of the compressed gas cylinder.
• Avoid forcing connections, using homemade adaptors or tampering with cylinders in any way.
• Comply with applicable regulations and contact the gas supplier for advice.

What should I know about Personal Protective Equipment?

If other methods, such as engineering controls, are not available or effective in controlling exposure to compressed gases, wear suitable personal protective equipment (PPE). Choosing the right PPE for a particular job is essential. Material Safety Data Sheets (MSDSs) should provide general guidance. Also obtain help from someone who knows how to evaluate the hazards of the job and how to select the proper PPE.

Avoid Skin Contact

When using gases that are harmful by skin contact, wear protective gloves, aprons or other clothing depending on the risk of skin contact. Choose clothing made of materials that resist penetration or damage by the chemical. The MSDS should recommend appropriate materials. If it does not, contact the gas supplier for specific information.

Protect Your Eyes and Face

Always wear eye protection when working with compressed gases. Avoid ordinary safety glasses. Use chemical safety goggles instead. In some cases, you should also wear a face shield (with safety glasses or goggles) to protect your face. The current CSA Standard Z94.3, "Eye and Face Protectors," provides advice on selection and use of eye and face protectors.

Avoid Breathing Harmful Gases

If respirators must be used for breathing protection, there should be a written respiratory protection program to follow. The current CSA Standard Z94.4, "Selection, Care, and Use of Respirators," gives guidance for developing a program. Follow all legal requirements for respirator use and approvals. These may vary between jurisdictions in Canada.
Sorbents in air-purifying respirator cartridges and canisters must be compatible with the chemical they are supposed to protect against. For example, oxidizable sorbents, such as activated charcoal, may not be acceptable if high concentrations of oxidizing gases are present. A hazardous reaction might occur. Keep in mind that air-purifying respirators do not protect against oxygen-deficient environments.
Know and be familiar with the right PPE for use in emergencies as well as during normal operations.
Wear the PPE needed for doing a particular job. It cannot provide protection if it is not worn.

What should I do in an emergency?

Act fast in emergencies such as chemical fires or gas cylinder leaks.

• Evacuate the area at once if you are not trained to handle the problem or if it is clearly beyond your control.
• Alert other people in the area to the emergency.
• Call the fire department immediately.
• Report the problem to the people responsible for handling emergencies where you work.
• Obtain first aid and remove all contaminated clothes if you have been exposed to harmful chemicals.

Note: All major compressed gas suppliers have emergency response teams. These teams can be activated by calling the telephone number that is usually printed on the shipping documents and MSDSs.
Locate emergency eyewash stations and safety showers wherever accidental exposure to gases that can damage skin or eyes is possible.
Only specially trained and properly equipped people should handle emergencies. Nobody else should go near the area until it is safe.
Planning, training and practicing for emergencies help people to know what they must do.
The MSDSs for the gases used are a starting point for drawing up an emergency plan. MSDSs have specific sections on spill and leak procedures, first aid instructions, and fire and explosion hazards. If the directions in each MSDS section are not clear or seem incomplete, contact the gas supplier or manufacturer for help. Many other sources can also help develop emergency plans. Local fire departments can assist with fire emergency plans and training. Occupational health and safety and environmental enforcement agencies, provincial safety associations, Compressed Gas Association Inc., St. John Ambulance, insurance carriers, professional societies in occupational health and safety, labour unions, some colleges and universities, and CCOHS can supply useful information. Specialized private consultants are also available.

What should I know about the storage area for oxidizing materials?

Store oxidizing materials separately away from processing and handling areas and away from other materials. Separate storage can reduce the risk of personal injury and damage in case of fires, spills or leaks. If totally separate storage is not possible, store oxidizing materials away from incompatible materials especially organic or other oxidizable materials (sometimes called reducing materials or reducing agents).
Some oxidizing materials are incompatible or may react with each other, sometimes violently. Do not store them beside each other. Check the reactivity data and storage requirements sections of the MSDS for details about what materials are incompatible with a specific oxidizer.
Walls, floors, shelving, and fittings in storage areas should be constructed of non-combustible materials. Wood impregnated with a fire-retardant material is not fully protected against the increased fire hazard caused by contact with oxidizers. Protect metal construction materials against corrosion by painting them with a compatible coating.
Ensure that floors in areas where oxidizers are stored are watertight, do not have cracks where these materials can lodge. Contain spills or leaks by storing in trays made from compatible materials. For larger containers, such as drums or barrels, provide dikes around storage areas, and sills or ramps at door openings.
Store oxidizer containers at a convenient height for handling, below eye level if possible, to reduce the risk of dropping containers. Avoid overcrowding in storage areas. Do not store containers in out-of-the-way locations where they could be forgotten.
Store containers away from doors. Although it is convenient to place frequently-used materials next to the door, they could cut off the escape route if an emergency occurs.
Store oxidizing materials in areas that are:

• Labelled with suitable warning signs.
• Well-ventilated.
• Supplied with adequate firefighting equipment including sprinklers, where appropriate.
• Supplied with suitable spill clean-up equipment and materials.
• Free of ignition sources.
• Accessible at all times.

Is storage temperature important?

Store oxidizing materials in dry, cool areas, out of direct sunlight and away from steam pipes, boilers or other sources of heat. Follow the chemical supplier's recommendations for storage temperatures. Some dangerously reactive oxidizing materials start to decompose at temperatures only a little above normal room temperatures. The decomposition can lead to an explosion under some conditions. For these oxidizers, ensure that the storage temperature is kept at least 14°C (25°F) below their decomposition temperature. Avoid storing any oxidizer at temperatures above 49°C (120°F).
Storage areas may need alarms that provide a warning when storage temperatures are higher or lower than required.

What are general precautions for storing oxidizing materials?

At all times:

• Allow only trained, authorized people into storage areas.
• Keep the amount of oxidizing materials in storage as small as possible.
• Inspect storage areas regularly for any deficiencies including damaged or leaking containers and poor housekeeping.
• Correct all deficiencies as soon as possible.

What are basic safe practices for working with oxidizing liquids and solids?

Following these basic safe practices will help protect you from the hazards of oxidizing materials:

• Read the Material Safety Data Sheets (MSDSs) for all of the materials used in your work.
• Know the hazards (fire/explosion, health, corrosivity, chemical reactivity) of the materials used in your work.
• Know which materials you work with are oxidizing materials.
• Store oxidizing materials in suitable labelled containers, in a cool, dry place, and according to any other conditions that may be required.
• Avoid or eliminate ignition sources (sparks, smoking, flames, hot surfaces) when working with oxidizing materials.
• Store, handle and use oxidizing materials in well-ventilated areas away from combustible and other incompatible materials.
• Handle containers safely to avoid damaging them.
• Dispense oxidizing materials carefully, using compatible equipment and containers.
• Keep containers closed when not in use.
• Keep only the smallest amounts possible (not more than one day's supply) in the work area.
• Do not return contaminated or unused oxidizers back to the original container.
• Practice good housekeeping, personal cleanliness and proper equipment maintenance.
• Handle and dispose of oxidizing wastes safely.
• Wear the appropriate personal protective equipment for each of the jobs you do.
• Know how to handle emergencies (fires, spills, personal injury) involving the oxidizing materials you work with.
• Follow the health and safety rules that apply to your job.

What are flammable and combustible liquids?

What are flammable and combustible liquids?
What is a flashpoint?
Does the liquid itself burn?
What are flammable or explosive limits?
What is an Autoignition Temperature?
How can flammable and combustible liquids be a fire or explosion hazard?
What is the danger of flashback?
Can flammable or combustible liquids be hazardous to my body?

What are flammable and combustible liquids?

Flammable and combustible liquids are liquids that can burn. They are classified, or grouped, as either flammable or combustible by their flashpoints. Generally speaking, flammable liquids will ignite (catch on fire) and burn easily at normal working temperatures. Combustible liquids have the ability to burn at temperatures that are usually above working temperatures.
There are several specific technical criteria and test methods for identifying flammable and combustible liquids. Under the Workplace Hazardous Materials Information System (WHMIS), flammable liquids have a flashpoint below 37.8°C (100°F). Combustible liquids have a flashpoint at or above 37.8°C (100°F) and below 93.3°C (200°F).
Flammable and combustible liquids are present in almost every workplace. Fuels and many common products like solvents, thinners, cleaners, adhesives, paints, waxes and polishes may be flammable or combustible liquids. Everyone who works with these liquids must be aware of their hazards and how to work safely with them.

What is a flashpoint?

The flashpoint of a liquid is the lowest temperature at which the liquid gives off enough vapour to be ignited (start burning) at the surface of the liquid. Sometimes more than one flashpoint is reported for a chemical. Since testing methods and purity of the liquid tested may vary, flashpoints are intended to be used as guides only, not as fine lines between safe and unsafe.

Does the liquid itself burn?

Flammable and combustible liquids themselves do not burn. It is the mixture of their vapours and air that burns. Gasoline, with a flashpoint of -40°C (-40°F), is a flammable liquid. Even at temperatures as low as -40°C (-40°F), it gives off enough vapour to form a burnable mixture in air. Phenol is a combustible liquid. It has a flashpoint of 79°C (175°F), so it must be heated above that temperature before it can be ignited in air.

What are flammable or explosive limits?

A material's flammable or explosive limits also relate to its fire and explosion hazards. These limits give the range between the lowest and highest concentrations of vapour in air that will burn or explode.
The lower flammable limit or lower explosive limit (LFL or LEL) of gasoline is 1.4 percent; the upper flammable limit or upper explosive limit (UFL or UEL) is 7.6 percent. This means that gasoline can be ignited when it is in the air at levels between 1.4 and 7.6 percent. A concentration of gasoline vapour in air below 1.4 percent is too "lean" to burn. Gasoline vapour levels above 7.6 percent are too "rich" to burn. Flammable limits, like flashpoints however, are intended as guides not as fine lines between safe and unsafe.

What is an Autoignition Temperature?

A material's autoignition or ignition temperature is the temperature at which a material self-ignites without any obvious sources of ignition, such as a spark or flame.
Most common flammable and combustible liquids have autoignition temperatures in the range of 300°C (572°F) to 550°C (1022°F). Some have very low autoignition temperatures. For example, ethyl ether has an autoignition temperature of 160°C (356°F) and its vapours have been ignited by hot steam pipes. Serious accidents have resulted when solvent-evaporating ovens were heated to temperatures above the autoignition temperature of the solvents used. Autoignition temperatures, however, are intended as guides, not as fine lines between safe and unsafe. Use all precautions necessary.

How can flammable and combustible liquids be a fire or explosion hazard?

At normal room temperatures, flammable liquids can give off enough vapour to form burnable mixtures with air. As a result, they can be a serious fire hazard. Flammable liquid fires burn very fast. They also give off a lot of heat and often clouds of thick, black, toxic smoke.
Combustible liquids at temperatures above their flashpoint also release enough vapour to form burnable mixtures with air. Hot combustible liquids can be as serious a fire hazard as flammable liquids.
Spray mists of flammable and combustible liquids in air may burn at any temperature if an ignition source is present. The vapours of flammable and combustible liquids are usually invisible. They can be hard to detect unless special instruments are used.
Most flammable and combustible liquids flow easily. A small spill can cover a large area of workbench or floor. Burning liquids can flow under doors, down stairs and even into neighbouring buildings, spreading fire widely. Materials like wood, cardboard and cloth can easily absorb flammable and combustible liquids. Even after a spill has been cleaned up, a dangerous amount of liquid could still remain in surrounding materials or clothing, giving off hazardous vapours.

What is the danger of flashback?

Vapours can flow from open liquid containers. The vapours from nearly all flammable and combustible liquids are heavier than air. If ventilation is inadequate, these vapours can settle and collect in low areas like sumps, sewers, pits, trenches and basements. The vapour trail can spread far from the liquid. If this vapour trail contacts an ignition source, the fire produced can flash back (or travel back) to the liquid. Flashback and fire can happen even if the liquid giving off the vapour and the ignition source are hundreds of feet or several floors apart.

Can flammable or combustible liquids be hazardous to my body?

The most obvious harm would be the danger of a fire or explosion. After the immediate danger of a fire, there are sometimes other properties of these liquids that may be hazardous to the body. Flammable and combustible liquids can also cause health problems depending on the specific material and route of exposure (breathing the vapour/mist, eye or skin contact, or swallowing). Some flammable and combustible liquids are corrosive. Many undergo dangerous chemical reactions if they contact incompatible chemicals such as oxidizing materials, or if they are stored improperly.
The Material Safety Data Sheet and the supplier's labels on the containers should tell you about all the hazards for the flammable and combustible liquids that you work with.
An example is 2-propanol (also known as: dimethylcarbinol, isopropanol, or isopropyl alcohol). It is a colourless liquid with a sharp odour like rubbing alcohol or resembling that of a mixture of ethanol and acetone. It is flammable liquid and vapour. Vapour is heavier than air and may spread long distances. Distant ignition and flashback are possible. It is also considered to be a mild central nervous system depressant. High vapour may cause headache, nausea, dizziness, drowsiness, incoordination, and confusion. It may also be irritating to the respiratory tract or eyes.

What is industrial ventilation?

Ventilation is the mechanical system in a building that brings in "fresh" outdoor air and removes the "contaminated" indoor air.
In a workplace, ventilation is used to control exposure to airborne contaminants. It is commonly used to remove contaminants such as fumes, dusts, and vapours, in order to provide a healthy and safe working environment. Ventilation can be accomplished by natural means (e.g., opening a window) or mechanical means (e.g., fans or blowers).
Industrial systems are designed to move a specific amount of air at a specific speed (velocity), which results in the removal (or "exhaust") of undesirable contaminants. While all ventilation systems follow the same basic principles, each system is designed specifically to match to the type of work and the rate of contaminant release at that workplace.

What is the purpose of a ventilation system?

There are four purposes of ventilation:

1. Provide a continuous supply of fresh outside air.
2. Maintain temperature and humidity at comfortable levels.
3. Reduce potential fire or explosion hazards.
4. Remove or dilute airborne contaminants.

Why have an industrial ventilation system?

Ventilation is considered an "engineering control" to remove or control contaminants released in indoor work environments. It is one of the preferred ways to control employee exposure to air contaminants.
Other ways to control contaminants include:

• eliminate the use of the hazardous chemical or material,
• substitute with less toxic chemicals,
• process change, or
• work practice change.

What are the parts of an industrial ventilation system?

Systems are composed of many parts including:

• an "air intake" area such as a hood or an enclosure,
• ducts to move air from one area to another,
• air cleaning device(s), and
• fan(s) to bring in outside air and exhaust the indoor contaminated air.

Each of these parts are discussed in this series of documents.

What are the basic types of ventilation systems?

There are two types of mechanical ventilation systems used in industrial settings:

Dilution (or general) ventilation reduces the concentration of the contaminant by mixing the contaminated air with clean, uncontaminated air.

Local exhaust ventilation captures contaminates at or very near the source and exhausts them outside.

What are main features of dilution ventilation?

Dilution, or "general", ventilation supplies and exhausts large amounts of air to and from an area or building. It usually involves large exhaust fans placed in the walls or roof of a room or building.
Dilution ventilation controls pollutants generated at a worksite by ventilating the entire workplace. The use of general ventilation distributes pollutants, to some degree, throughout the entire worksite and could therefore affect persons who are far from the source of contamination.
Dilution ventilation can be made more effective if the exhaust fan is located close to exposed workers and the makeup air is located behind the worker so that contaminated air is drawn away from the worker's breathing zone. See Figure 1 for examples of good and poor dilution ventilation design.
When used to control chemical pollutants, dilution must be limited to only situations where:

• the amounts of pollutants generated are not very high,
• their toxicity is relatively moderate, and
• workers do not carry out their tasks in the immediate vicinity of the source of contamination.

It is therefore unusual to recommend the use of general ventilation for the control of chemical substances except in the case of solvents which have admissible concentrations of more than 100 parts per million.

What are the limitations of dilution ventilation?

As a method for protecting workers, it is important to know that dilution ventilation:

• Does not completely remove contaminants.
• Cannot be used for highly toxic chemicals.
• Is not effective for dusts or metal fumes or large amounts of gases or vapours.
• Requires large amounts of makeup air to be heated or cooled.
• Is not effective for handling surges of gases or vapours or irregular emissions.

Regular "floor" or "desk" fans are also sometimes used as a method of ventilation, but these fans typically blow the contaminant around the work area without effectively controlling it. Opening doors or windows can be used as dilution ventilation, but again, this method is not reliable since air movement is not controlled.
As a general note, the air or "volumetric" flow rate of dilution ventilation depends largely on the how fast the contaminant enters the air as well as the efficiency that fresh air mixes with workroom air.

What is local exhaust ventilation?

Local exhaust system is used to control air contaminants by trapping them at or near the source, in contrast to dilution ventilation which lets the contaminant spread throughout the workplace. Local exhaust is generally a far more effective way of controlling highly toxic contaminants before they reach the workers' breathing zones. This type of system is usually the preferred control method if:

• Air contaminants pose serious health risk.
• Large amounts of dusts or fumes are generated.
• Increased heating costs from ventilation in cold weather are a concern.
• Emission sources are few in number.
• Emission sources are near the workers' breathing zones.

In a general way, a local exhaust system operates similar to a household vacuum cleaner with the hose as close as possible to the place where dirt would be created.

What are the components of local exhaust ventilation?

A local exhaust system has six basic elements (see Figure 6):

• A "hood" or opening that captures the contaminant at the source.
• Ducts that transport the airborne chemicals through the system.
• An air cleaning device that removes the contaminant from the moving air in the system (not always required).
• Fans that move the air through the system and discharges the exhaust air outdoors.
• An exhaust stack through which the contaminated air is discharged.
• Make up air that replaces the exhausted air.

How do I know which type of ventilation system is best for my workplace?

All industrial ventilation systems, when designed properly, should be able to provide long-term worker protection. The two types of ventilation, dilution and local exhaust, are compared in the following table.

Comparison of Ventilation Systems
Dilution Ventilation		Local Exhaust Ventilation
Advantages	Disadvantages	Advantages	Disadvantages
Usually lower equipment and installation costs.	Does not completely remove contaminants.	Captures contaminant at source and removes it from the workplace.	Higher cost for design, installation and equipment.
Requires less maintenance.	Cannot be used for highly toxic chemicals.	Only choice for highly toxic airborne chemicals.	Requires regular cleaning, inspection and maintenance.
Effective control for small amounts of low toxicity chemicals.	Ineffective for dusts or metal fumes or large amounts of gases or vapours.	Can handle many types of contaminants including dusts and metal fumes.
Effective control for flammable or combustible gases or vapours.	Requires large amounts of heated or cooled makeup air.	Requires smaller amount of makeup air since smaller amounts of air are being exhausted.
Best ventilation for mobile or dispersed contaminant sources.	Ineffective for handling surges of gases or vapours or irregular emissions.	Less energy costs since there is less makeup air to heat or cool.

In general, what are limitations of any ventilation system?

Some limitations include:

• The systems deteriorate over the years because of to contaminant build-up within the system, especially filters.
• Require ongoing maintenance.
• Regular and routine testing is needed to identify problems early and implement corrective measures.
• Only qualified persons should make modifications to a ventilation system to make sure the system continues to work effectively.

The following is an example of changes that can affect how a system works:
A hood and branch are added to an existing duct. The local exhaust ventilation pulls air into the system from the new location, which will reduce the airflow from other locations that are further away from the exhaust fan. Again, airflow will all be affected. The result is that the system will plug more rapidly and the airflows at the other hoods may not be adequate enough to remove contaminants.

What should I know about make-up air?

An important and sometimes overlooked aspect of local ventilation is the need to provide enough air to replace the air that is exhausted from the workplace. If enough make-up air is not provided when large volumes of air are exhausted, the workplace becomes "starved" for air and negative pressure is created.
Negative pressure in the workplace increases resistance on the ventilation system causing it to move less air. Air will also enter a building through cracks around doors or windows or other small openings to try to "equal" the rate of air being removed. The result is that workers may be exposed to cold air in the winter, and additional heating costs may occur. One simple way to judge if a building is under an excessive negative pressure is if you have difficulty opening a door that pushed into the room or building (the air wants to force the door closed).
A separate intake fan, located away from the exhaust fans, should be used to bring in fresh, uncontaminated air from outside. This air must be clean and heated in winter or cooled in summer, as needed.

Ammonia Production

In 1909 Fritz Haber established the conditions under which nitrogen, N₂(g), and hydrogen, H₂(g), would combine using

• medium temperature (~500^oC)
• very high pressure (~250 atmospheres, ~351kPa)
• a catalyst (a porous iron catalyst prepared by reducing magnetite, Fe₃O₄).
  Osmium is a much better catalyst for the reaction but is very expensive.

This process produces an ammonia, NH₃(g), yield of approximately 10-20%.
The Haber synthesis was developed into an industrial process by Carl Bosch.
The reaction between nitrogen gas and hydrogen gas to produce ammonia gas is exothermic, releasing 92.4kJ/mol of energy at 298K (25^oC).

N2(g) nitrogen

+

3H2(g) hydrogen

heat, pressure, catalyst

2NH3(g) ammonia

H = -92.4 kJ mol-1

By Le Chetalier's Principle:

• increasing the pressure causes the equilibrium position to move to the right resulting in a higher yeild of ammonia since there are more gas molecules on the left hand side of the equation (4 in total) than there are on the right hand side of the equation (2). Increasing the pressure means the system adjusts to reduce the effect of the change, that is, to reduce the pressure by having fewer gas molecules.
• decreasing the temperature causes the equilibrium position to move to the right resulting in a higher yield of ammonia since the reaction is exothermic (releases heat). Reducing the temperature means the system will adjust to minimise the effect of the change, that is, it will produce more heat since energy is a product of the reaction, and will therefore produce more ammonia gas as well
  However, the rate of the reaction at lower temperatures is extremely slow, so a higher temperature must be used to speed up the reaction which results in a lower yield of ammonia.

The equilibrium expression for this reaction is:

Keq = [NH3]2 [N2][H2]3

As the temperature increases, the equilibrium constant decreases as the yield of ammonia decreases.

Temperature (oC) Keq 25 6.4 x 102 200 4.4 x 10-1 300 4.3 x 10-3 400 1.6 x 10-4 500 1.5 x 10-5

Rate considerations:

• A catalyst such as an iron catalyst is used to speed up the reaction by lowering the activation energy so that the N₂ bonds and H₂ bonds can be more readily broken.
• Increased temperature means more reactant molecules have sufficient energy to overcome the energy barrier to reacting (activation energy) so the reaction is faster at higher temperatures (but the yield of ammonia is lower as discussed above).
  A temperature range of 400-500^oC is a compromise designed to achieve an acceptable yield of ammonia (10-20%) within an acceptable time period.
  

  At 200oC and pressures above 750atm there is an almost 100% conversion of reactants to the ammonia product. Since there are difficulties associated with containing larger amounts of materials at this high pressure, lower pressures of around 200 atm are used industrially. By using a pressure of around 200atm and a temperature of about 500oC, the yield of ammonia is 10-20%, while costs and safety concerns in the biulding and during operation of the plant are minimised

  During industrial production of ammonia, the reaction never reaches equilibrium as the gas mixture leaving the reactor is cooled to liquefy and remove the ammonia. The remaining mixture of reactant gases are recycled through the reactor. The heat released by the reaction is removed and used to heat the incoming gas mixture.

Uses of Ammonia

Industry	Use
Fertilser	production of: ammonium sulfate, (NH4)2SO4 ammonium phosphate, (NH4)3PO4 ammonium nitrate, NH4NO3 urea, (NH2)2CO,also used in the production of barbiturates (sedatives), is made by the reaction of ammonia with carbon dioxide CO2 carbon dioxide + 2NH3 ammonia H2NCOONH4 ammonium carbonate heat, pressure (NH2)2CO urea
Chemicals	synthesis of: nitric acid, HNO3, which is used in making explosives such as TNT (2,4,6-trinitrotoluene), nitroglycerine which is also used as a vasodilator (a substance that dilates blood vessels) and PETN (pentaerythritol nitrate). sodium hydrogen carbonate (sodium bicarbonate), NaHCO3 sodium carbonate, Na2CO3 hydrogen cyanide (hydrocyanic acid), HCN hydrazine, N2H4 (used in rocket propulsion systems)
Explosives	ammonium nitrate, NH4NO3
Fibres & Plastics	nylon, -[(CH2)4-CO-NH-(CH2)6-NH-CO]-,and other polyamides
Refrigeration	used for making ice, large scale refrigeration plants, air-conditioning units in buildings and plants
Pharmaceuticals	used in the manufacture of drugs such as sulfonamide which inhibit the growth and multiplication of bacteria that require p-aminobenzoic acid (PABA) for the biosynthesis of folic acids, anti-malarials and vitamins such as the B vitamins nicotinamide (niacinamide) and thiamine.
Pulp & Paper	ammonium hydrogen sulfite, NH4HSO3, enables some hardwoods to be used
Mining & Metallurgy	used in nitriding (bright annealing) steel, used in zinc and nickel extraction
Cleaning	ammonia in solution is used as a cleaning agent such as in 'cloudy ammonia'

A Brief History

At the beginning of the 20^th century there was a shortage of naturally occurring, nitrogen-rich fertilisers, such as Chile saltpetre, which prompted the German Chemist Fritz Haber, and others, to look for ways of combining the nitrogen in the air with hydrogen to form ammonia, which is a convenient starting point in the manufacture of fertilisers.This process was also of interest to the German chemical industry as Germany was preparing for World War I and nitrogen compounds were needed for explosives.
The hydrogen for the ammonia synthesis was made by the water-gas process (a Carl Bosch invention) which involves blowing steam through a bed of red hot coke resulting in the separation of hydrogen from oxygen. The nitrogen was obtained by distillation of liquid air, then by cooling and compressing air.
These days, the hydrogen is produced by reforming light petroleum fractions or natural gas (methane, CH₄) by adding steam:

CH4(g) + H2O(g)

Ni catalyst ----------> 700oC

CO(g) + 3H2(g)

Enough steam is used to react with about 45% of the methane (CH₄), the rest of the methane is reacted with air:

2CH4(g) +

O2(g) + 4N2(g) (air)

Ni catalyst --------->

2CO(g) + 4H2(g) + 4N2(g)

All the carbon monoxide (CO) in the mixture is oxidised to CO₂ using steam and an iron oxide catalyst:

CO(g) + H2O(g)

iron oxide catalyst ------------------>

H2(g) + CO2(g)

The carbon dioxide (CO₂)is removed using a suitable base so that only the nitrogen gas (N₂)and hydrogen gas (H₂)remain and are used in the production of ammonia (NH₃).
In ammonia production the hydrogen and nitrogen are mixed together in a ratio of 3:1 by volume and compressed to around 200 times atmospheric pressure.

Production

Feedstock:The original feedstock for the old 1,000-ton-per day Allied Chemical ammonia plant at Hopewell, VA, USA, was water gas (i.e., illuminating gas), the same type of gas that was manufactured for heating, lighting and cooking in cities before natural gas became available. It was made from coke and steam. Allied/Hopewell made enough such gas per day to have supplied a city the size of New York
Feedstocks may range from, ethane through petroleum naphtha to petroleum gas oils. The basic processing scheme used for such feedstocks is the same as for a natural gas feedstock, however ammonia eventually is made by mixing hydrogen with nitrogen. It requires a catalytic conversion reactor followed by cooling the hot reactor effluent gas: first by generating steam with the hot effluent gas and then by using mechanical refrigeration to separate out the liquified anhydrous ammonia. It also requires compressing the catalytic reactor feed gases to a range of 100 to 250 bar, depending on the reactor process being used.

Here is the ammonia process with Gas feedstock which is a guideline to the original and most used process.

2. DESCRIPTION OF PRODUCTION PROCESSES
2.1 Production Processes in Operation in Europe
Two main types of production process for ammonia synthesis gas are currently in operation in Europe:-
- Steam reforming of natural gas or other light hydrocarbons (Natural Gas Liquids,
     Liquefied Petroleum Gas, Naphtha)
- Partial oxidation of heavy fuel oil or vacuum residue
In at least one partial oxidation unit, natural gas is used as feedstock. Coal gasification and water electrolysis are no longer in use in the European ammonia industry.
The ammonia synthesis process is principally independent of the type of synthesis gas pro-duction process, but synthesis gas quality influences the loop design and operating conditions.
A block diagram of the conventional steam reforming process is shown in Figure 1. (In some cases, a separate auxiliary boiler is required). About 85% of world ammonia production is based on steam reforming concepts [3]. A process description is given in 2.2.1.
For heavier feedstocks than naphtha, partial oxidation with oxygen is used in the synthesis gas production. A block diagram of a typical partial oxidation process is shown in Figure 2, and a process description is given in 2.2.5.
2.2 BAT Production Processes
No single process can be identified as BAT for the production of ammonia. In this chapter the characteristics of BAT processes based on available feedstocks are described. Other BAT processes may also exist.
Natural gas reforming with steam and air is the simplest and most efficient way of ammonia synthesis gas production. Comparing natural gas reforming, heavy oil and coal gasification gives the following approximate relative consumption figures, based on modern technological standards for each route, at European economic conditions:-

	Natural Gas	Heavy Oil	Coal
Energy consumption	1.0	1.3	1.7
Investment cost	1.0	1.4	2.4
Production cost	1.0	1.2	1.7

Based on the known resources of fossil raw materials, it is likely that natural gas will domi-nate as the feedstock for ammonia for the next 50 years at least. In the very long term, 50-200 years, one might expect coal to take over, based on world reserves and consumption rate. Heavy oil may be attractive under special environmental concerns, when natural gas is not available and the partial oxidation process could solve a waste problem (heavy residues, plastics recycle).
For the present time and the near future, the steam/air reforming concepts based on natural gas and other light hydrocarbons are considered to be the dominating group of BAT production processes. The BAT reforming processes can be divided into the following types:-
- Conventional steam reforming with a fired primary reformer and stoichiometric air secondary   reforming (stoichiometric H/N-ratio)
- Steam reforming with mild conditions in a fired primary reformer and excess air sec-ondary reforming   (under-stoichiometric H/N-ratio)
- Heat exchange autothermal reforming, with a process gas heated steam reformer (heat exchange   reformer) and a separate secondary reformer, or in a combined autothermal reformer, using excess or enriched air (under-stoichiometric or stoichio-metric H/N-ratio)
For heavy feedstocks, partial oxidation is considered as the BAT production process.
All three reforming versions, and partial oxidation of heavy residues, are operated in Europe today.
The following description concentrates on presenting the conventional steam reforming process and only deviations and additions will be described for the other BAT processes.
2.2.1 Conventional steam reforming
2.2.1.1 Overall conversion
The theoretical process conversions, based on methane feedstock, are given in the following approximate formulae:-
0.88CH₄ + 1.26Air + 1.24H₂O ----->   0.88CO₂ + N₂ + 3H₂
N₂ + 3H₂ -----> 2NH₃
The synthesis gas production and purification normally take place at 25-35bar pressure. The ammonia synthesis pressure is usually in the range 100-250bar. For more detailed process flow sheets refer to Ullmann [3].
2.2.1.2 Feedstock desulphurisation
Most of the catalysts used in the process are sensitive to sulphur and sulphur compounds. The feedstock normally contains up to 5mg S.Nm^-3 as sulphur compounds. The feed-gas is pre-heated to 350-400 °C, usually in the primary reformer convection section, and then treated in a desulphurisation vessel, where the sulphur compounds are hydrogenated to H₂S, typically using a cobalt molybdenum catalyst, and then adsorbed on
pelletised zinc oxide:-
R-SH + H₂  -----> H₂ S + RH
H₂ S + ZnO   -----> ZnS + H₂O
In this way, the sulphur is removed to less than 0.1ppm S in the gas feed. The zinc sulphide remains in the adsorption bed. The hydrogen for the reaction is usually recycled from the synthesis section.
2.2.1.3 Primary reforming
The gas from the desulphuriser is mixed with process steam, usually coming from an extraction turbine, and the steam/gas mixture is then heated further to 500-600 °C in the convection section before entering the primary reformer. In some new or revamped plants the preheated steam/gas mixture is passed through an adiabatic pre-reformer and reheated in the convection section, before entering the primary reformer. (Special pre-reformer catalysts are offered by several suppliers). Also, in some plants, part of the process steam is supplied by feed-gas saturation.
The amount of process steam is given by the process steam to carbon molar ratio (S/C-ratio), which should be around 3.0 for the BAT reforming processes. The optimum ratio depends on several factors, such as feedstock quality, purge gas recovery, primary reformer capacity, shift operation, and the plant steam balance. In new plants the optimum S/C-ratio may be lower than 3.0.
The primary reformer consists of a large number of high-nickel chromium alloy tubes filled with nickel-containing reforming catalyst. The overall reaction is highly endothermic and additional heat is required to raise the temperature to 780-830 °C at the reformer outlet.
The composition of the gas leaving the primary reformer is given by close approach to the following chemical equilibria:-
CH₄ + H₂0  <---> CO + 3H₂                       H⁰₂₉₈ = 206 kJ.mol^-1
C0 + H₂0   <---> CO₂ + H₂                             H⁰₂₉₈ = -41 kJ.mol ^-1
The heat for the primary reforming process is supplied by burning natural gas or other gaseous fuel, in the burners of a radiant box containing the tubes.
The flue-gas leaving the radiant box has temperatures in excess of 900 °C, after supplying the necessary high level heat to the reforming process. Thus only about 50-60% of the fuel’s heat value is directly used in the process itself. The heat content (waste heat) of the flue-gas is used in the reformer convection section, for various process and steam system duties. The fuel energy requirement in the conventional reforming process is 40-50% of the process feed-gas energy.
The flue-gas leaving the convection section at 100-200 °C is one of the main sources of emissions from the plant. These emissions are mainly CO₂, NO_x, with small amounts of SO₂and CO.
2.2.1.4 Secondary reforming
Only 30-40% of the hydrocarbon feed is reformed in the primary reformer because of the chemical equilibria at the actual operating conditions. The temperature must be raised to increase the conversion. This is done in the secondary reformer by internal combustion of part of the gas with the process air, which also provides the nitrogen for the final synthesis gas. In the conventional reforming process the degree of primary reforming is adjusted so that the air supplied to the secondary reformer meets both the heat balance and the stoichiometric synthesis gas requirement.
The process air is compressed to the reforming pressure and heated further in the primary reformer convection section to around 600 °C. The process gas is mixed with the air in a burner and then passed over a nickel-containing secondary reformer catalyst. The reformer outlet temperature is around 1,000 °C, and up to 99% of the hydrocarbon feed (to the primary reformer) is converted, giving a residual methane content of 0.2-0.3% (dry gas base) in the process gas leaving the secondary reformer.
The process gas is cooled to 350-400 °C in a waste heat steam boiler or boiler/superheater downstream from the secondary reformer.
2.2.1.5 Shift conversion
The process gas from the secondary reformer contains 12-15% CO(dry gas base) and most of the COis converted in the shift section according to the reaction:-
CO + H₂O  <---> CO₂ + H₂                          H^O₂₉₈ = -41 kJ.mol^-1
In the High Temperature Shift (HTS) conversion, the gas is passed through a bed of iron oxide/chromium oxide catalyst at around 400 °C, where the COcontent is reduced to about 3% (dry gas base), limited by the shift equilibrium at the actual operating temperature. There is a tendency to use copper containing catalyst for increased conversion. The gas from the HTS is cooled and passed through the Low Temperature Shift (LTS) converter.
This LTS converter is filled with a copper oxide/zinc oxide-based catalyst and operates at about 200-220 °C. The residual COcontent in the converted gas is about 0.2-0.4% (dry gas base). A low residual CO content is important for the efficiency of the process.
2.2.1.6 CO₂ removal
The process gas from the low temperature shift converter contains mainly H₂, N₂, CO₂and the excess process steam. The gas is cooled and most of the excess steam is condensed before it enters the CO₂removal system. This condensate normally contains 1,500-2,000ppm of ammonia800-1,200ppm of methanol. Minor amounts of amines, formic acidand acetic acidcould be present in the condensate. All these components should be stripped from the condensate and/or recycled in BAT processes. The heat released during cooling/condensation is used for:-
-The regeneration of the CO₂scrubbing solution
- Driving an absorption refrigeration unit
- Boiler feedwater preheat
The amount of heat released depends on the process steam to carbon ratio. If all this low-level heat is used for CO₂removal or absorption refrigeration, high-level heat has to be used for the feedwater system. An energy-efficient process should therefore have a CO₂removal system with a low heat demand.
The CO₂is removed in a chemical or a physical absorption process. The solvents used in chemical absorption processes are mainly aqueous amine solutions ( Mono Ethanolamine (MEA), Activated MethylDiEthanolamine (aMDEA)or hot potassium carbonatesolutions. Physical solvents are glycol dimethylethers (Selexol), propylene carbonate and others. The MEA process has a high regeneration energy consumption and is not regarded as a BAT process.
For new ammonia plants the following CO 2 removal processes are currently regarded as BAT:-
- aMDEA standard 2-stage process, or similar
- Benfield process (HiPure, LoHeat), or similar
- Selexol or similar physical absorption processes
Concepts such as Pressure Swing Adsorption (PSA) should also be regarded as BAT in some new plants but in such cases CO₂removal is not the only function of the PSA unit.
The typical range of heat consumption in the modern chemical absorption process is 30-60MJ.kmol ^-1CO₂. The physical absorption processes may be designed for zero heat consumption, but for comparison with the chemical processes, the mechanical energy requirements have also to be considered.
Residual CO₂contents are usually in the range 100-1,000ppmv, dependent on the type and design of the removal unit. Contents down to about 50ppmv are achievable.
2.2.1.7 Methanation
The small amounts of CO and CO₂, remaining in the synthesis gas, are poisonous for the ammonia synthesis catalyst and must be removed by conversion to CH₄ in the methanator:-
CO + 3H₂  -----> CH₄ + H₂O
CO₂+ 4H₂ -----> CH₄ + 2H₂O
The reactions take place at around 300 °C in a reactor filled with a nickel containing cata-lyst. Methane is an inert gas in the synthesis reaction, but the water must be removed before entering the converter. This is done firstly by cooling and condensation downstream of the methanator and finally by condensation/absorption in the product ammonia in the loop or in a make-up gas drying unit.
2.2.1.8 Synthesis gas compression and ammonia synthesis
Modern ammonia plants use centrifugal compressors for synthesis gas compression, usually driven by steam turbines, with the steam being produced in the ammonia plant. The refrigeration compressor, needed for condensation of product ammonia, is also usually driven by a steam turbine.
The synthesis of ammonia takes place on an iron catalyst at pressures usually in the range 100-250bar and temperatures in the range 350-550 °C:-
N₂ + 3H₂   <---> 2NH₃                    H⁰₂₉₈ = -46 kJ.mol ^-1 NH ₃
Only 20-30% is reacted per pass in the converter due to the unfavourable equilibrium conditions. The ammonia that is formed is separated from the recycle gas by cooling/condensa-tion, and the reacted gas is substituted by the fresh make-up synthesis gas, thus maintaining the loop pressure. In addition, extensive heat exchange is required due to the exothermic reaction and the large temperature range in the loop. A newly developed ammonia synthesis catalyst containing ruthenium on a graphite support has a much higher activity per unit of volume and has the potential to increase conversion and lower operating pressures.
Synthesis loop arrangements differ with respect to the points in the loop at which the make-up gas is delivered and the ammonia and purge gas are taken out. The best arrangement is to add the make-up gas after ammonia condensation and ahead of the converter. The loop purge should be taken out after ammonia separation and before make-up gas addition. This configuration is dependent on the make-up gas being treated in a drying step before entering the loop. A make-up gas containing traces of water or carbon dioxide must be added before ammonia condensation, with negative effects both to ammonia condensation and energy.
Conventional reforming with methanation as the final purification step, produces a synthesis gas containing inerts (methane and argon) in quantities that do not dissolve in the condensed ammonia. The major part of these inerts is removed by taking out a purge stream from the loop. The size of this purge stream controls the level of inerts in the loop to about 10-15%. The purge gas is scrubbed with water to remove ammonia before being used as fuel or before being sent for hydrogen recovery.
Ammonia condensation is far from complete if cooling is with water or air and is usually not satisfactory (dependent on loop pressure and cooling medium temperature). Vapourising ammonia is used as a refrigerant in most ammonia plants, to achieve sufficiently low ammonia concentrations in the gas recycled to the converter. The ammonia vapours are liquified after recompression in the refrigeration compressor.
2.2.1.9 Steam and power system
Steam reforming ammonia plants have high-level surplus heat available for steam production in the reforming, shift conversion, and synthesis sections, and in the convection section of the primary reformer. Most of this waste heat is used for high pressure steam production for use in turbines for driving the main compressors and pumps and as process steam extracted from the turbine system.
A modern steam reforming ammonia plant can be made energetically self-sufficient if nec-essary, but usually a small steam export and electricity import are preferred.
2.2.2 Steam reforming with excess air secondary reforming
2.2.2.1 Process flowsheet
Some processes are designed for reduced primary reforming by moving some of the duty to the secondary reformer because of the marginal low efficiency of the primary reformer. A brief description is given of features diverging from the conventional concept in the fol-lowing paragraphs. These features are:
--Decreased firing in the primary reformer
- Increased process air flow to the secondary reforming
- Cryogenic final purification after methanation
- Lower inert level of the make-up syngas
2.2.2.2 Decreased firing in the primary reformer
Decreased heat supply in the primary reformer means that the process outlet temperature is lowered (to about 700 °C), the firing efficiency increases, and the size and cost of the primary reformer are reduced. The milder operating conditions prolong catalyst, catalyst tube and outlet header service lives. The extent of reforming is reduced according to the lower heat supply and lower temperature. Generally, a slight decrease in steam to carbon ratio is acceptable, compared to the conventional concept.
2.2.2.3 Increased process air supply to the secondary reformer
Decreased heat supply in the primary reformer means that increased internal firing is necessary to achieve approximately the same degree of total reforming. A somewhat higher methane slip, and thus a lower secondary reformer outlet temperature is acceptable and preferable in this type of process, as methane is removed in the final purification step.
The process air requirement is about 50% higher than in the conventional process. This means increased compression capacity and energy. The process air compressor is usually driven by a gas turbine with the exhaust gas from the turbine being used as combustion air in the primary reformer. Some excess steam is available for export when using a gas turbine.
2.2.2.4 Cryogenic final purification
In the cryogenic purifier all the methane and the excess nitrogen are removed from the synthesis gas as well as a part of the argon. The cooling is produced by depressurisation and no external supply is needed. The purified syngas is then practically free of all impurities, except for a small amount of argon. The cryogenic unit also receives the purge from the synthesis section and delivers an off-gas for fuel.
2.2.2.5 Lower syngas inert level
The removal of essentially all impurities from the make-up synthesis gas is a significant improvement, compared to the conventional purification by methanation only. Higher conversion per pass and reduced purge flow, together result in a more efficient process.
2.2.3 Heat exchange autothermal reforming
From a thermodynamic point of view it is wasteful to use the high-level heat of the secondary reformer outlet gas and the primary reformer flue-gas, both at temperatures around 1,000 °C, simply to raise steam. Recent developments are to recycle this heat to the process itself, by using the heat content of the secondary reformed gas in a newly-developed primary reformer (gas heated reformer, heat exchange reformer), thus eliminating the fired furnace. Surplus air or oxygen-enriched air is required in the secondary reformer to meet the heat balance in this autothermal concept.
Emissions to the atmosphere are reduced significantly by eliminating the flue-gas from the primary reformer. NO_x emissions may be reduced by 50% or more, depending on the extent of auxiliary combustion in the plant, compared to conventional steam reforming.
Two processes of this kind are in operation, and some others are at the pilot stage. All these processes are considered as BAT production processes. Recently it has been reported that capacities in the range of 1,800t.d^-1 can be built.
2.2.4 BAT reforming processes for new plants
The modern versions of the conventional steam reforming and excess air reforming processes will still be used for new plants for many years to come. Developments are expected to go in the following directions:-
- Lowering the steam to carbon ratio
- Shifting duty from primary to secondary reformer
- Improved final purification
- Improved synthesis loop efficiency
- Improved power energy system
- Low NO_x burners
- Non iron based ammonia synthesis catalyst
The new autothermal concepts are expected to be developed further, and will continue the developments outlined above.
2.2.5 Partial oxidation of heavy oils
2.2.5.1 Process description
The partial oxidation process is used for the gasification of heavy feedstocks such as residual oils and coal. Extremely viscous hydrocarbons and plastic wastes may also be used as fractions of the feed. The partial oxidation process offers an alternative for future utilisation of such wastes.
An air separation unit is required for the production of oxygen for the partial oxidation step. The nitrogen is added in the liquid nitrogen wash to remove impurities from the synthesis gas and to get the required hydrogen/nitrogen ratio in the synthesis gas.
The partial oxidation gasification is a non-catalytic process taking place at high pressure (>50bar) and temperatures around 1,400 °C. Some steam is added for temperature modera-tion. The simplified reaction pattern is:-
-CH_n - + 0.5O₂   -----> CO + n/2H₂
Carbon dioxide, methane and some soot are formed in addition. The sulphur compounds in the feed are converted to hydrogen sulphide. Mineral compounds in the feed are transformed into specific ashes. The process gas is freed from solids by water scrubbing after waste heat recovery and the soot is recycled to the feed. The ash compounds are drained with the process condensate and/or together with a part of the soot. In at least two units in Europe, the soot is separated from soot water in a mainstream filtration stage, to avoid ash build-up in the gasification cycle downstream units. The heavy metals, such as V, Ni and Fe are recovered. The hydrogen sulphide in the process gas is separated in a selective absorption step and reprocessed to elementary sulphur in a Claus unit.
The shift conversion usually has two high temperature shift catalyst beds with intermediate cooling. Steam for the shift conversion is supplied partially by a cooler-saturator system and partially by steam injection.
CO₂is removed by using an absorption agent which might be the same as that in the sulphur removal step. Residual traces of absorption agent and CO₂are then removed from the process gas, before final purification by a liquid nitrogen wash. In this unit practically all the impurities are removed and nitrogen is added to give the stoichiometric hydrogen to nitrogen ratio.
The ammonia synthesis is quite similar to that used in steam reforming plants, but simpler and more efficient, due to the high purity of synthesis gas from liquid nitrogen wash units and the synthesis loop not requiring a purge.
2.2.5.2 Steam and power system
Auxiliary boilers are required if the compressors are steam-driven. The flue-gas from these power plants is the main source of emissions which are mainly SO₂, NO_x, and CO₂. The site emissions are very low if the compressors are driven by imported electric power.
2.2.5.3 Future improvements
No major improvements are to be expected concerning process efficiency and plant investment costs. However, partial oxidation will continue to be interesting in the future, due to its feedstock flexibility. The separation and disposal of the soot and especially the ashes are necessary to adapt to deteriorating residue qualities or alternative raw material sources.

General failures:
failure of the air coil installed in the primary reformer
absorber and stripper vents fires


Corrosion:It all depends on the system. If you install a stainless steel valve in direct contact with cast iron piping, you may induce galvanic corrosion. Check OSHA's web site for ammonia. They have a picture of completely corroded SS piping.
Stainless may still be the best. Just fully address all mechanical integrity questions. Set up a periodic assessment of fitness for continued service.
An ultrsasonic device can measure inside corrosion under intact outside coating. It may be a good idea to buy the equipment ($500-1,000) and continuously check your entire system.

Pump ware:
Not being sure as to the exact problem with the o-rings, is it swelling, shrinking or explosive decompression..little chunks missing. Ammonia can be a difficult product to seal in pumps. We consulted with Parker O-Ring and started using a Neoprene C-873-70 for rotary vane pump mechanical seals.
Most of those installations problems subsided once we used it. I would contact the Parker Rep. Our office in Houston did and got the help we needed.
I had the same problems in a Viking pump, used as a low temperature transfer pump. I was told that these pumps were noted for blowing their o-rings. I bit the bullet and installed a Cornell transfer pump and I haven't had any problems since. This may be the solution to your problem. It sure did fix mine.

Contacts for processing:There are several companies you can contact to discuss your questions. First is EEC in Baltimore Md. Their web site and contact info can be found at www.eec1.com. Might talk to Herbert Spencer at EEC. Next is Wahlco in Santa Ana, California and they are at www.wahlco.com. Talk to Barry Southam or Mike Fujita. Another urea system is offered by Fuel Tech and they can also be found on the web. Talk to William Sun after finding their contact information on the web.
Another urea system is offered by Chemithon in Seattle Wa. Talk to Ken Reimers at 206-937-1187 or send an e-mail to: kreimers@chemithon.com.
These companies are the leaders in urea use for power plant DeNOx sytems that require an ammonia source from urea, that I am aware of at this time.


Economic considerations:
The total ammonia production capacity in the United States is 19,500,000 tons per year. As of January 1, 2001, the amount of ammonia capacity operating was 12,000,000 tons per year. It is expected that the 7,500,000 tons per year of unused capacity will not be used until the price of natural gas falls below $6 per 1,000,000 BTUs
Waste retrofitting, and EnvirnomentThe production of ammonia can be divided into six main steps:

1. Synthesis Gas Preparation: which includes desulfurization; steam reforming, coal gasification, oil oxidation, electrolysis; and shift conversion.
2. Syn Gas Purification: which includes Carbon dioxide removal, methanation, etc.
3. Syn Gas Compression.
4. Ammonia Synthesis: reaction of hydrogen and nitrogen to form ammonia.
5. Ammonia Separation and Recovery.
6. Recycle: recycle of un-recovered ammonia and the syn gas back to the synthesis compressor.

The complex reaction involved in the production ammonia leads to the generation of a number of wastes. These wastes are mostly in gaseous form. During the recent years the fertilizer industry has implemented many waste reduction methods and techniques. As a result of which today the waste release and generation is much lower than what it was a few years ago. According to the Fertilizer Institute (TFI 2001), since 1987, the waste emissions in the U.S alone have decreased by approximately 75% in the nitrogen fertilizer industry [15].

Control & Conservation Techniques:

The following methods and techniques can be used for controlling emissions from ammonia production plants:
Using Natural Gas as the raw material:The use of natural gas as the raw material (feed stock) is the best way to decrease the waste emissions from an ammonia plant. The natural gas has high hydrogen content and a higher heating value than most of the hydrocarbons. Processes based on heavy hydrocarbons such as oils and coal, generate waste many time greater than natural gas based plants.
Excess Air Reforming:The IFA recommends the use of excess air reforming for improving the waste conservation and control of the ammonia plants [2]. The recommendation is based upon the fact that primary reformers have low efficiencies. By reducing the share of primary reformer in the reforming reaction, the primary reformer size and energy demand can be decreased. While at the same time the life and efficiency of the catalysts and the catalyst tubes is increased. This will increase the reaction share of the secondary reformer. By supplying the air in excess to the secondary reformer, the internal firing in the secondary reformer is increased, which makes it possible to achieve the same degree of total reforming as in the case of conventional steam reforming process. The reduced need of energy to the primary reformer will decrease the use of fuel gases and the hence the emissions of combustion flue gases.
Heat Exchange Autothermal Reforming:The heat-exchange autothermal reforming is based upon the principle that the heat of reaction in the secondary reformer can be used to supply the heat needed to the primary reformer for reforming reaction. This eliminates the fired furnace and hence the reformer flue gases, thus significantly reducing the NOx and carbon oxides emissions. Excess air is supplied to the reforming exchanger, to increase the internal firing, which increases the reforming reaction. According to the IFA, these processes can reduce the NOx emissions by 50% or more as compared to the conventional steam reforming processes [2]. Kellogg Brown & Root (formerly M.W. Kellogg Company), introduced its new process in the 1990s, called Kellogg Brown Root Advanced Ammonia Process plus (KAAPplus [11]), which is based upon the same principle.
Improving CO2 Removal Processes:Most of the CO2 removal processes used in the ammonia production use some type of absorbent for CO2 removal. These absorbents have to be regenerated after their use. Those absorbents should be used which are easier to regenerate and do not result in toxic releases. During the regeneration operation proper control of the process can also reduce the waste emissions. Reducing the use of organic absorbents such as amines can also decrease toxic releases to the environment. Use of CO2 removal processes, which do not use any chemicals, is another way of reducing the emissions. Processes such as adsorption and membrane treatment can be used. However, the main problems associated with the membrane processes are the huge pressure drops in the gases after membrane treatment and temperature sensitivity of membranes. The cost of energy to overcome this pressure drop has to be justified before membranes can be used in the ammonia production processes.
Improving Purge Gas Recovery:Improving the purge gas recovery can also control waste emissions. Ammonia is recovered from the synthesis loop purge, while the remaining gases along with small amounts of ammonia are sent to the primary reformer for use as fuel. If the argon present in the purge gas can be removed (i.e. after ammonia removal), then this gas can be recycled back to the converter. Thus increasing the ammonia production.
Better Final Purification Techniques:The main reason for purge requirement in the synthesis loop is the build up of inerts in the recycle stream. Accumulation of these inerts hinders the ammonia conversion in the reactor. The two inert gases present in the feed gas to the ammonia reactor are argon and methane. These inerts keep on accumulating in the recycle stream making it necessary to purge in order to avoid over accumulation of these inerts. If the inert gases can be separated from the ammonia reactor feed gas, then there would be no need for purging. Furthermore, it will also improve the conversion reaction and also decrease the operating cost of the synthesis loop. Rectification columns, Cryogenic purification units, or a combination of both can be used for this purpose. These units can be used prior to the ammonia reactor, after the methanation step.
Ammonia Synthesis:The low conversion rate of the ammonia converters is another reason for waste generation. Most of the conventional ammonia converters (reactors) have a 12-13% conversion. Only recently some reactors have been developed which have conversions as high as 17%. The main reason for this meager conversion is that the ammonia synthesis reaction is highly exothermic. Due to this reason, the temperature of the reaction gases increases as ammonia is formed, increasing the rate of the reaction, but shifting the chemical equilibrium in the opposite direction. Thus the temperature for maximum conversion decreases with the increase in ammonia concentration. With the shift of the reaction in the opposite direction, decomposition of ammonia starts. Also the tremendous amount of heat evolved during the reaction increases the temperature of the catalyst bed to its maximum potential. Further increase in the temperature can permanently damage the catalysts. In order to avoid this situation, the ammonia converters are provided with cooling systems, which remove the heat of reaction. Heat quenching and heat exchanger systems are the two of the many methods used for this purpose. Ammonia synthesis can be improved by improving the converter design. Using improved heat removal techniques and catalyst with higher temperature resistance can improve the ammonia conversion rate. gases increases as ammonia is formed, increasing the rate of the reaction, but shifting the chemical equilibrium in the opposite direction. Thus the temperature for maximum conversion decreases with the increase in ammonia concentration. With the shift of the reaction in the opposite direction, decomposition of ammonia starts. Also the tremendous amount of heat evolved during the reaction increases the temperature of the catalyst bed to its maximum potential. Further increase in the temperature can permanently damage the catalysts. In order to avoid this situation, the ammonia converters are provided with cooling systems, which remove the heat of reaction. Heat quenching and heat exchanger systems are the two of the many methods used for this purpose. Ammonia synthesis can be improved by improving the converter design. Using improved heat removal techniques and catalyst with higher temperature resistance can improve the ammonia conversion rate.

Ammonia Properties1. Identification

Name Commonly used synonyms C.A.S. Registry number EINECS Number EINECS Name Molecular formula

: : : : : :

Ammonia Liquid Ammonia 7664-41-7 231-635-3 Anhydrous Ammonia NH3

2. Hazards to Man and the Environment
To manAmmonia is toxic by inhalation and pulmonary oedema may occur up to 48 hours after severe exposure and could be fatal.
Vapours cause irritation and watering of eyes and in the presence of moisture, irritation of the skin.
Liquid ammonia splashes may produce severe burns to the skin and permanent damage to the eyes.
In enclosed spaces (eg vessels, closed workshops) ammonia vapour may be flammable/explosive.
To the environmentAmmonia is toxic to aquatic life.
3. Physical and Chemical Properties

Appearance	Colourless liquefied gas.
Odour	Pungent, suffocating.
pH water solution (1%)	11.7
Melting point (triple point)	-77.7°C
Boiling point	-33.4°C at 101.3 kPa
Explosive limits	16-27% NH3 by vol. in air at 0 °C
Auto-ignition temperature	651°C
Vapour pressure	1013kPa at 25°C
Relative vapour density	0.6 (air =1)
Solubility in water	529g/l-1 at 20 °C
Solubility in organic solvents	Soluble in alcohol, acetone, chloroform
Liquid density	0.6386g/cm-3(at 0°C, 101.3kPa)
Gas density	0.7714g/l-1 (at 0°C, 101.3kPa)

Envirnomental Data can be found Environmental data for the BAT production

4. ENVIRONMENTAL DATA

Environmental data for the BAT production processes are generally known with a high degree of reliability, while data for storage and transfer are more uncertain and of much less importance. Hence, data for production will be given the highest attention.
4.1 Production Input Requirements
4.1.1 >4.1.1 Feedstock
The typical feedstock requirements for modern plants are (approximately):-

	Conventional reforming:	22.1 GJ(LHV*).t -1 NH
	Excess air reforming :	23.4 GJ(LHV).t -1 NH
	Autothermal reforming :	24.8 GJ(LHV).t -1 NH
	Partial oxidation :	28.8 GJ(LHV).t -1 NH

* Lower Heating Value
4.1.2 Fuel
Assuming an efficient stand-alone plant with no energy export and no other import than feed-stock and fuel, the fuel requirements are (approximately):-

	Conventional reforming:	7.2-9.0 GJ(LHV).t-1 NH
	Excess air reforming :	5.4-7.2 GJ(LHV).t -1NH
	Autothermal reforming :	3.6-7.2 GJ(LHV).t-1 NH
	Partial oxidation :	5.4-9.0 GJ(LHV).t-1 NH

The uncertainty in autothermal reforming is mainly due to the type of compressor drives.
4.1.3 Water and air
In the steam reforming processes process steam is taken from the plant steam system, usually from an extraction turbine. The net consumption according to the stoichiometic conversion is 0.6-0.7kg.kg^-1 NH₃ , the total supply at a S/C ratio of 3.0 will be about 1.5kg.kg^-1 NH₃ .. In partial oxidation much less steam is fed to the gasification reactor, but additional steam is needed in shift conversion (1.2kg.kg^-1 NH₃ in total).
Process air supply: In conventional reforming the nitrogen supply equals the ammonia nitrogen content plus the purge losses, ie. about 0.85kg N 2 .kg^-1 NH₃ or about 1.1kg air.kg^-1 NH₃ . In the excess air reforming and gas heated reformer cases the process air requirements are about 50% and 100% higher, respectively. In the partial oxidation process the amount of air fed to the air separation unit is approximately 4kg.kg^-1 NH₃ , based on the oxygen requirement.
Boiler feedwater: Assuming all steam condensates are recycled, only the process steam consumption has to be replaced by outside water. This will be 0.7-1.5kg.kg^-1 NH₃ (see above), depending on process condensate recycle or not. Small additional losses and potential import/export have to be allowed for in practice.
Air and/or water for cooling: Will differ from one site to another.
4.1.4 Solvents and additives
The consumption of solvent in the CO₂ removal unit should not normally exceed 0.02-0.04kg.t^-1 NH₃ , or about 2kg.h^-1 for a BAT capacity plant. Solvent losses are mainly caused by leaks.
The usual treatment additives and regeneration agents are used in the boiler feedwater preparation units. The consumption figures should not differ from those of a standard steam boiler plant at the same location.
4.1.5 Catalysts
Approximate consumption figures, based on average filling volumes and normally recommended operating periods, for a gas based conventional reforming plant, are given in the table below. The consumptions refer to a capacity of 1,500t.d^-1.

	Catalyst type	Typical replacement m3.y-1
	Hydrodesulphurisation	1
	Sulphur removal	5
	Primary	5
	Secondary reforming	4
	High temperature shift	10
	Low temperature shift	20
	Methanation	2
	Synthesis	10

Actual consumptions in existing plants may differ considerably from the guidance figures above.
4.1.6 Energy requirements
The total energy requirement in the reforming BAT processes is 28.8-31.5GJ (LHV).t^-1 NH₃ for a stand-alone plant with no energy export and no other import than feedstock and fuel. When using process waste heat in a gas heated reformer, the process itself will not produce enough steam to drive all the compressors. A part of the power needed may then be imported from a more efficient power plant outside the process plant. In such cases the total energy consumption may be lowered and approach the present practical minimum of 27 GJ(LHV).t ^-1 NH₃.
3.
In partial oxidation plants the total energy requirement is 36.9(35.1-37.8)GJ(LHV).t ^-1 NH₃ .. This includes imported power and/or auxiliary steam for driving the machinery.
4.2 >4.2 Production Output
4.2.1 Ammonia
Ammonia production in the typical size BAT plant is 1,000^-1,500t.d^-1 ,500t.d^-1 (300,000-500,000t.y^-1). The production not used in downstream plants on site is stored as described in Chapter 3.
Commercial anhydrous ammonia has two grades of purity:-
- Anhydrous ammonia min. 99.7 wt %, water content (about 0.2% wt)
- Anhydrous ammonia min. 99.9 wt %
4.2.2 Carbon dioxide
Carbon dioxide is produced according to the stoichiometric conversion and may be recovered for down-stream uses. The carbon dioxide production in steam/air reforming of natural gas is 1.15-1.30kg.kg^-1 NH₃, dependent on the degree of air reforming. A CO₂ /NH₃ mole ratio of 0.5 (weight ratio 1.29), the stoichiometric ratio for urea production, is obtainable in the heat exchange reformer concepts. In partial oxidation of residual oils the CO₂ production is 2-2.6kg.kg^-1 NH₃ , dependent on feedstock C/H ratio.
Carbon dioxide in the combustion gases is not included in the above figures, but is shown in Figure 3.
4.2.3 Sulphur
In BAT partial oxidation most (87-95%) of the sulphur content of the feed to the gasifier is recovered in the Claus unit.
4.2.4 >4.2.4 Steam export
Modern steam reforming processes can be designed with no steam export or with some export of low/medium pressure steam if this can be favourably used on site. Steam export is usual in excess air reforming processes where the process air compressor is driven by a gas turbine, and in cases when electric power is used for driving one or more of the main compressors.
Processes with gas heated primary reforming may be designed for zero steam export even with some power import or gas turbine drive.
The partial oxidation process has a steam deficit if all compressors are steam driven.
4.3 Production Emissions and Wastes
4.3.1 Emissions into air from steam reforming plants
From steam reforming plants with a fired primary reformer emissions into air come from the following sources:-
- Flue-gas from the primary reformer
- Vent gas from CO₂ removal
- Breathing gas from oil buffers (seals/compressors)
- Fugitive emissions (from flanges, stuffing boxes etc.)
- Purge and flash gases from the synthesis section (usually added to the
-  primary reformer fuel)
- Non-continuous emissions (venting and flaring)
4.3.1.1 Flue-gas from the primary reformer
The flue-gas volume, at 3% (dry gas base) oxygen, for a gas-based conventional steam reforming plant producing 1,500t.d ^-1 , is approximately 200,000Nm₃ .h ^-1, containing about 8% CO₂ (dry gas base), corresponding to 500kg CO₂.t^-1 NH₃ .. The flue-gas volume from excess air reforming may be lower. The other pollutants in the flue-gas are:-
NO_x : 200-400mg.Nm^-3 , (98-195ppmv), or 0.6-1.3kg.t^-1 NH₃ expressed as NO₂
SO 2 : 0.1-2mg.Nm^-3 ,, (<0.01kg.t^-1) ,, depending on fuel
CO: <10mg.Nm^-3 ,, (<0.03kg.t ^-1)
The NO_x emission depends on several factors and the following features reduce the emission:-
- Low combustion air and fuel gas preheat
- Steam/inert injection
- Low ammonia content in injected purge-gas
- Low excess oxygen
- Low NO_x burners
- Post-combustion measures
The SO₂ emission comes from the sulphur in the fuel gas and can be calculated by a simple mass balance.
4.3.1.2 Vent gases from CO₂> removal
More or less of the CO₂ product may have to be vented, depending on the CO₂ requirements of other production facilities on the site. In some cases, high purity CO₂ is used, while an air-CO₂ mixture from a stripping column is vented. The CO₂ contains small traces of synthesis gas and absorption solvent vapour.
4.3.1.3 Breathing gas from oil buffers
This contains traces of NH₃ , synthesis gas and lube oil.
4.3.1.4 >4.3.1.4 Fugitive emissions
The diffuse emissions from flanges, stuffing boxes etc. should be minimised.
4.3.1.5 >4.3.1.5 Purge and flash gases
The purge and flash gases from the synthesis section are usually washed with water to remove/recover ammonia, and the purge gas may be treated in a recovery unit, before routing the off-gases to the primary reformer fuel gas system. The off-gases are thus combusted and end up as part of the flue-gas. It is important to remove the ammonia as far as possible, as it will contribute considerably to the flue-gas NOx emission.
4.3.1.6 Non-continuous emissions
Emission of NOx during flaring synthesis gas at start-up or trip situations is estimated to be 10-20kg.h ^-1 as NO ₂ [1]. Some plants without a flare, vent to the atmosphere.
4.3.2 >4.3.2 Emissions into air from heat exchange reforming
The flue-gas volume (from auxiliary fired equipment) and thus NO_xand CO₂ emissions are considerably reduced, as these processes have much more internal combustion than the fired reformer processes because all the reforming process heat is generated by internal combustion.-  Total C0₂ emissions are fixed by the energy consumption. For self-sufficient plants the flue-gas volume in heat exchange reforming is about 50% of the figure for conventional steam reforming. In plants with power import the flue-gas volumes are lower. Reduction of NO_x emissions by 80% has been claimed.
4.3.3 Emissions into air from partial oxidation plants
The partial oxidation process has the same emission sources as described for the reforming-  process except for the primary reformer flue-gas. A partial oxidation plant may also have auxiliary boiler(s) for power steam production, if more efficiently off-site produced power is not available. The fuel to the auxiliary boiler/superheater together with possible scrubbing equipment determines the amount of CO₂ in the flue-gas. Tail gas from sulphur recovery will also contain sulphur oxides. This means that the CO₂ emission from partial oxidation plants (max 1,500mg.Nm^-3 ) is higher than in the reformer flue-gas. Other additional emissions may be H₂S (0.3ppmv), methanol (max. 100ppmv), CO (30ppmv), and dust (traces, max. 50mg.Nm^-3 ). NO_xemission (max. 700mg.Nm^-3 ) depends on the factors listed for the reformer flue-gas and the nitrogen content of the fuel.
Excess nitrogen is usually vented.
4.3.4 Emissions into water/P>
Pollution problems related to water, during normal operation, may occur due to process condensates or due to the scrubbing of waste gases containing ammonia. In partial oxidation, soot and ash removal may cause pollution problems, if not properly handled.
Process condensate is found primarily in the condensation section prior to the CO₂-  removal, of the order of 1m 3 per ton NH₃produced. Without treatment this condensate can contain up to 1kg of ammonia and 1kg methanol per m³ . More than 95% of the dissolved gases can be recovered by stripping with process steam and are recycled to the process.
The stripped condensate can be re-used as boiler feedwater make-up after treatment by ion exchange. Total recycle is obtained in this way. In some cases the process condensate is used for feed-gas saturation and thus recycled to the process.
Usually the ammonia absorbed from purge and flash gases is recovered in a closed loop so that no aqueous ammonia emissions occur. Emissions into water from the production plant during normal operation can thus be fully avoided.
Soot from gasification in partial oxidation processes is usually recovered and recycled to the process. Traces of soot and slag are emitted to water.
4.3.5 Solid wastes
The BAT ammonia processes do not normally produce solid wastes. Spent catalysts and mol.sieves have to be removed and valuable metals are recovered from them. In partial oxidation plants sulphur is recovered in the Claus plant and can be used as feedstock in sulphuric acid units. The ash can be upgraded and used as an ore substitute.
4.4 Environmental Data for Ammonia Storage and Transfer
In a refrigerated storage, the cold losses are balanced by recompressing and recondensing the evaporated ammonia. During recompression, some inerts containing also traces of ammonia cannot be condensed but must be flared or scrubbed with water. Small continuous emissions may thus occur, in addition to minor non-continuous emissions during loading operations.
4.5 Environmental Hazards Associated with Emissions and Wastes
The production of ammonia is relatively clean compared to many other chemical processes. During the normal operation of a reforming plant, only the NO_x and CO₂-  emissions have to be considered. In partial oxidation plants with oil-fired auxiliary boilers the reduction of SO₂ -  emissions can be achieved by using low sulphur fuel oil. Generally the emissions from modern ammonia plants have little environmental impact.
4.6 Emission Limits and Guideline Values for Ammonia Production in Some West-European Countries
Two types of emission values are of importance:-
- Legally binding emission limit values for specific pollutants which apply for
- ammonia production
- Guideline values which are not legally binding but provide the background for
-  requirements laid down in individual permits
Specific legally binding emission limits for ammonia production are only laid down in Germany. In the Netherlands and in Germany limits for emissions from boilers have been laid down which include chemical reactors.
Specific emission guideline values are laid down in the United Kingdom.
With regard to the other countries, no national emission limits or guidelines are fixed for ammonia production plants. Very often the values are the subject of negotiations between the operator and the authority responsible for granting licences. In some countries, these authorities are of local character, so that even within one and the same country, different air pollution requirements may apply for comparable plants. At least in the Benelux countries and Ireland, the licensing authorities take into account emission limits applied in other countries, in particular those laid down in Dutch and German law, in their negotiations with operators. In practice, these values play the role of guideline values.
Indirectly, the emission limits laid down for combustion installations play an important role because the energy consumption of an ammonia plant is relatively high. The emissions from a fired reformer or auxiliary boilers should conform with emission limits and guideline values adopted by the Council of EC in Directive 88/609/EEC or applied by the state.
More detailed information is given in Reference [1].
7. OCCUPATIONAL HEALTH & SAFETY< The occupational health and safety issues associated with ammonia production and storage are:-
- Fire/explosion injuries
- Poisoning
- Suffocation
Fires or explosions from the involuntary ignition of leaks are credible, especially when these occur in the feed-gas and synthesis gas systems (hydrocarbons, hydrogen).
The most important toxic components are CO from potential leaks in the synthesis gas generation and shift areas and NH₃ from leaks in the ammonia synthesis and ammonia handling areas. In partial oxidation plants H₂S and SO₂ are present in the sulphur removal/recovery sections. Traces of carbonyls (iron and nickel) may form during operation.
Suffocation due to lack of oxygen may occur at points where the breathing air has been diluted with inert gases. In ammonia plants CO₂ and N₂ are potentially suffocating gases.
ACGIH [4] occupational exposure limits for ammonia and other components associated with ammonia production are given in the table below. All the figures are ppmv:-

Component	TLV-TWA (8hr)	TLV-STEL (15min)
NH3	25	35
NO2	3	5
SO2	2	5
H2 S	10	15
CO	50	400
CO2	5,000	30,000

The figures are subject to updating and may vary between European countries.
Full health and safety information is given in Safety Data Sheets which must be available and updated. General product information on ammonia is given in Appendix 2.
Ammonia plants have high technological standards and need professional management, operating and maintenance working routines and personnel. Precautions taken to prevent accidents and injuries during operation are incorporated in the operating and safety procedures for the plant.


8. SUMMARY OF BAT EMISSION LEVELS
8.1 Achievable Emission Levels for New Plants<
The following emission levels can be achieved for new ammonia plants. These levels relate to steady-state production, not accounting for peaks which can occur during the unsteady transient conditions of start-up and shut-down and during emergencies.
8.1.1 Emissions into air

	ppmv	mg.Nm-3	kg.t-1 of product
NOx (as NO2 at 3% O2)	75	150	0.45
SO2 (partial oxidation plants):                                           as for combustion plants.

8.1.2 Emissions into water<
NH₃ or NH₄ (as N)                     0.1kg.t^-1 of product
8.1.3 Waste material<
Spent catalysts etc.                 <0.2kg.t^-1 of product
Reclaiming of raw materials from spent catalyst by specialised companies prior to their disposal is common practice in the ammonia industry.
In new reforming plants the total energy consumption should not exceed 29.3GJ(LHV).t^-1 and process condensate recycle should be a pre-requisite.
8.2 Achievable Emission Levels for Existing Plants
The following emission levels can be achieved for existing ammonia plants. As for new plants, these levels do not account for peak values during unsteady or transient conditions.   Contributions from ammonia-containing purge gases can be excluded from these figures in special cases, when authorised locally.
8.2.1 Emissions into air<

	ppmv	mg.Nm-3	kg.t-1 of product
NOx  (as NO2  at 3% O2)	150	200-400	0.9
SO2  (partial oxidation plants):                                       as for combustion plants.

8.2.2 Emissions into water
NH₃  or NH₄  (as N)                     0.1kg.t^-1 of product
8.2.3 Waste material
Spent catalysts etc.                     <0.2kg.t^-1 of product
8.3 Cost of Pollution Control Measures
The costs of pollution control measures in the fertilizer industry are difficult to generalise as they depend on a number of factors such as:-
- The emission target or standard to be met
- The type of process, the degree of integration with other processes on site,
    production volumes,
    type of raw materials being used etc.
- Whether the plant is new so that the design can be optimised with respect to
    pollution abatement, or whether the plant is an existing one requiring revamping or
    end-of-pipe pollution abatement equipment
Generally, it is more economic to incorporate the pollution abatement system at the process design stage rather than revamping or "adding-on" equipment at a later stage.
Process condensate recycle can be included to bring existing plants to BAT standards for emissions into water and a rough investment of the order of 2.9 to 3.3 million EUR can be anticipated (1,500t.d^-1).<


5. EMISSION MONITORING<
As outlined in Chapter 4, the emissions of pollutants to be expected from ammonia production are mainly:-
- CO₂, NO_x, SO₂, and CO in the flue-gas from steam reforming processes with a fired
    primary reformer and/or auxiliary boilers
- SO₂ from the sulphur removal and recovery systems in partial oxidation processes
- CO₂ and traces of removal solvents and synthesis gas in vent streams from the CO₂        removal system
- Small non-continuous and fugitive emissions
- NH₃ and methanol in process condensates (if not recycled)
The following emissions into air should be monitored as part of a proper supervision:-
- NO_x in flue-gases
- SO₂ in flue-gases (may be calculated by mass balance instead of monitoring
    emission, if S input is known)
- SO₂ and H₂S from sulphur removal/recovery systems in partial oxidation processes
The other emissions into air need not be monitored. CO₂ emission can be calculated from fuel specification and energy consumption, CO emission is fixed by the operating conditions and usually stable and low. Non-continuous and fugitive emissions are difficult to measure.
The frequency of monitoring depends on local circumstances and the operating stability of the actual plant. Under normal operating conditions, measurements once a month are usually sufficient.
Methods for discontinuous and continuous measurements of NO_x, SO₂ and H₂S are available and are to a large extent standardised at national level (Norme Belge/Belgische norm, British Standard, AFNOR, Verein Deutscher Ingenieure, Nederlands Normalisatie Instituut). Chemiluminescence or photometry are the most widely used methods for NO_x. SO₂ is determined by Infra Red (IR) absorption techniques. Traces of H₂S are measured by lead acetate.
Emissions into water from new plants are virtually zero as process condensates are recycled and monitoring is not normally required. In existing plants without recycle of process condensate, the ammonia and methanol content should be monitored.
A description of available methods for monitoring emissions is given in Appendix 1.

Introduction

 

 

A heart attack is most commonly caused by a sudden blockage of the blood supply to the heart muscle itself, for example a blood clot. The main risk is that the heart will stop beating.

• Persistent central chest pain - often described as vice-like or a heavy crushing pressure
• Pain spreading (radiating) to the jaw, neckand down one or both arms
• Breathlessness
• Discomfort high in the abdomen, similar to indigestion
• Possible collapse without warning
• Ashen skin and blueness at the lips
• Rapid, weak pulse which may be irregular
• Profuse sweating, skin cold to the touch
• Gasping for air (air hunger)
• Nausea and/or vomiting.

EHSQ BLOG :http://dramarnathgiri.blogspot.in/?view=magazine

The Indian Supreme Court as Environmental Activist 

 

India’s apex court, the Supreme Court, has been playing an important role as a steward of environmental protection. In a recent order, it required the central government to set up a national environment regulator with offices in every state by March 31, 2014, entrusted with appraising and approving projects for environmental clearances. In fact, Indian democracy is known not only for its judicial independence, but, importantly, for offering numerous instances of judicial activism that has been facilitated by the “innovative” tool of Public Interest Litigation (PIL) – a judicial pill for relief against executive wrongs.
PIL originated in 1979 when the judicial ruling in the Hussainara Khatoon v. State of Bihar case led to the release of more than 40,000 under trial prisoners in the Indian state of Bihar. In a subsequent judgment (S.P. Gupta v. Union of India, 1981), Justice P.N. Bhagwati and Justice V.R. Krishna Iyer articulated the concept of PIL, stating that any member of public can file a petition in the High Court against a violation of the legal or constitutional right(s) of any person or class of persons who are helpless in approaching the court for relief, and can directly approach the Supreme Court in case the latter’s fundamental right has been breached. In the People’s Union for Democratic Rights v. Union of India case, 1982, Justice Bhagwati clarified the purpose of PIL, stating that it is “a strategic arm of the legal aid movement which is intended to bring justice within the reach of the poor masses, who constitute the low visibility area of humanity..[PIL] is a totally different kind of litigation from the ordinary traditional litigation.” Over the years, PIL has increased Indian judicial engagement with environmental issues tremendously, although some judiciary experts consider this phenomenon a dilution of the original purpose of PIL.
Nevertheless, judicial activism has been instrumental in addressing the environmental cause.  It was because of the Supreme Court that the right to life and liberty, a fundamental right under Article 21, came to include the right to a healthy environment. As a result, an individual can approach it directly when the public interest is at stake due to environmental harm. Acting on a PIL to curb industrial pollution of water bodies, for instance, the Court issued notices to the Union government, Central Pollution Control Board, and 19 states to implement pollution control norms and the “polluter pays” principle.
On past occasions as well, the Court has issued notices and directives to the central and state governments on multiple environmental issues, such as freezing production licenses granted to manufacturers of endosulfan pesticide, relocating hazardous industries from the National Capital Region, issuing guidelines for the prevention of noise pollution, and requiring civic bodies to file affidavits detailing measures to manage plastic waste. A well-known, controversial and rather stern order came in 1998 (M.C. Mehta v. Union of India), when the Supreme Court mandated the conversion of all diesel-powered buses in Delhi to Compressed Natural Gas (CNG)-driven ones, to check air pollution. It also imposed hefty fines on diesel bus operators who failed to comply with the ruling. As a result, as of June 2012, some 13,000 buses were running  on CNG in Delhi. Similarly, hearing a petition in 2012, the Court admonished both the central government and the state governments of Delhi, Haryana and Uttar Pradesh for persistent pollution of the Yamuna river. The bench stated: “It is important for this court to take this matter to its logical conclusion and not permit state authorities and its officers to leave it mid-way particularly when thousands of crores [nearly $2 billion on sewage plants to treat effluents] have been spent by the union of India and other public bodies.” Importantly, the empathy of the Court for the common man is reflected in the following statement: “It’s common man’s money that has been spent and nothing has happened.” As such, among other directives, it asked the Indian Institute of Technology (IIT) to employ its expertise in cleaning up the river.
Taking on the “mining mafia” has been another concern of the Supreme Court. Quite recently, it asked the central government to submit by January 27 the Justice Shah Commission report on illegal mining in the states of Odisha and Jharkhand. The report is expected to reveal the illegal financial transactions and expose the culprits. Last year, the Court permitted 118 legal mines in the state of Karnataka to reopen, lifting a two-year ban. However, it cancelled the leases of mining projects planned outside the sanctioned area of the Bellary district.
It merits a caveat that the Supreme Court’s intervention is not a panacea for all environmental ills. Further, its activism has been construed by legal experts as an encroachment on the executive domain of policymaking. Also, dealing with environmental challenges requires administrative and police accountability, “grassroots level governance,” public enlightenment and civic sense, and corporate responsibility. Nevertheless, the role of the judiciary is pivotal to environmental protection. In China, for instance, environmental protesters complain of an absence of the rule of law and demand a judicial role in handling environmental cases. According to China Dialogue, for example, during the 11^th Five-Year Plan period (2006-2010), the Chinese Ministry of Environmental Protection received more than 300,000 environmental complaints, but “less than 1% of environmental disputes are resolved through legal channels.” In India, by contrast, the public and judiciary lie on the one side of the spectrum and the politico-bureaucratic authorities are on the other when judicial redress is sought against authorities’ acts of omission and commission. In fact, the mechanism of PIL has helped elevate the common man in India to the unofficial status of a powerful individual who can fall back on the apex court and the state high courts to flog bureaucracy into action that is in the public interest.

Image: Thiru Murugan

While this guide to important environmental issues is not comprehensive, if you’re new to green or simply want a refresher overview, this list neatly summarizes some of our most pressing environmental concerns … some of which cannot be solved simply via creative upcycling or small-space living.
1. Climate Change
Global warming has been concerning scientists for decades, but Al Gore legitimized the crisis with his controversial film An Inconvenient Truth. From the melting polar ice caps to catastrophic weather and threatened ecosystems, not only is climate change real, scientists agree that humans are influencing climate change with our production of greenhouse gases (mainly stemming from carbon dioxide and methane). What can you do? How bad is it? Why do so many people still think climate change isn’t real? Is it real? These are just some of the issues worth exploring. The good news is that despite the urgency of the crisis, there are exciting technological developments as well as meaningful lifestyle changes you can make to help.
2. Energy
Clean energy vs. dirty energy. Renewable energy. Energy independence. Petroleum. Biofuels. Coal. ANWR and offshore drilling. Even Paris Hilton has something to say about energy. Energy is second only to climate change in significance, but the picture isn’t as clear as one might think. China is heavily criticized, but did you know the state of California is worse? Look for plenty of myth-busting and interesting news to come, as well as practical tips to reduce your own energy dependence. Though no single energy source is going to be the solution, positive developments toward a cleaner future are happening every single day.
3. Waste
With the immediate looming problems of climate change and energy, focus has shifted away from landfill waste, but this is a serious problem. The world has largely gotten accustomed to a throwaway lifestyle, but that’s neither healthy nor sustainable. Waterways are choked with trash and modernized nations ship their undesirable leftovers to the developing world. Fashion fashion, fast food, packaging and cheap electronics are just some of the problems. The amount of waste the industrialized world generates is shocking. Water bottles are the defining symbol of this critical issue. Fortunately, people are becoming aware of the consequences of “fast consumption” and there are many simple changes you can make in your own life to help significantly reduce landfill waste.
4. Water
Pure Water is in short supply. Our global reserves of drinkable water are a fraction of 1% and 1 in 5 humans does not have access to potable (safe) water. Many people do not realize that strife has already broken out in some stressed regions. There are many potential solutions, some promising, others challenging. Desalinization is an energy-inefficient, expensive option. But there are many things you can do. (Hint: it starts with turning off the faucet when you brush.)
5. Food
Biofuels have turned into a global controversy – the idea that people may causing the starvation of millions in order to fuel their SUVs is sickening. And yet that’s not the whole picture. For example, eating hamburgers has as much or more impact on the global food picture as the use of biofuels. And then there’s the whole issue of “food miles” – at first, local seemed logical, but the situation is more complex than that. It’s all about resources and efficiency. There are big questions: can we support the world without turning to vegetarianism? We know that the planet can’t afford the Western way of eating. It would take 5 earths to support that lifestyle! What about hunting – is that good for the environment? Look for more articles soon exploring the complicated world of food. Fortunately, there are a multitude of tasty diets that incorporate greener values, so it’s not necessary to adhere to veganism, for example.
6. Consumption
This is directly tied to waste. It is well-known that the industrialized world simply consumes in a way that is not sustainable. And the developing world is rapidly imitating the model. Sustainability in the most compelling sense is about long-term solvency. The way we live now is borrowing against the future. Reducing consumption, and smart consumption, are both necessary – and there are many ways to go about doing this. Some methods are pure geek, some are high tech, and some are just common sense. And once you start exploring, you’ll see that it’s actually fun.
7. Land Management
From desertification to polar ice melting to erosion and deforestation, existing land management choices are not serving the planet or its inhabitants very well. The 1990s saw some headway with forest management but the Bush administration’s various initiatives (most notoriously, “Healthy Forests”) have set back progress by decades. There is very little land left that is undeveloped, either with structures or roads. And there is virtually no land left that is not subject to light or noise pollution. The modern green movement believes that in order to create a sustainable future, people will need to return to the conservation spirit Americans were once famous for. That’s a value system that includes meaning, adventure, and self-sufficiency – no wonder so many people are getting inspired.
8. Ecosystems and Endangered Species
The good news is that some species have made a comeback. The bad news is that many more species are now under threat, including indicator species and evolutionarily unique species. (When an indicator species becomes threatened, endangered, or worse, extinct, this means an entire ecosystem faces collapse.) The consequences can have global impact. From the most unusual endangered animals to a complete list of indicator species for key ecosystems and how you can help, you’ll find plenty of fascinating information soon. (Be sure to bookmark this post and check back for updates and links.)
9. The Science of Public Health Issues
Our tomatoes have fish DNA? Killer bugs are on the loose? Superweeds are taking over corn fields? Wild animals are sprouting extra limbs? Autism is on the rise? WTF! What on earth (literally) is going on? From genetic manipulation and cloning to public health issues and food and drug contamination, get to know the new, strange, important and most interesting green issues related to genetic science, agribusiness, public health and more. What’s this about electromagnetic fields? Is all that exhaust on my commute killing me? Do cell phones really cause cancer? Will soy milk give me man boobs? How much of our groundwater is contaminated? Is smog getting worse or better? How much acid rain is there? Why can’t I drink out of streams? These are just some of the fascinating questions you can read about here in future posts. You can look forward to sane analysis that debunks myth and takes fear-mongering to task.
Did you guess the tenth issue? There are more issues, but those are the most critical green challenges. It will take a combination of technological developments and lifestyle changes to address these challenges successfully – and that begins with learning, which is perhaps the most important environmental challenge of all, rounding out the list at 10. Stay tuned for more!

Delhi world’s most polluted city: Study

Chetan Chauhan, Hindustan Times New Delhi, January 29, 2014 It’s no surprise that pollution is a perpetual problem in India. But it’s definitely disheartening to hear that India has slipped 32 ranks in the global Environment Performance Index (EPI) 2014 to rank a lowly 155 and its capital Delhi has earned the dubious tag of being the world’s most polluted city.
A comparative study of 178 countries on nine environmental parameters released earlier this month by the US-based Yale University shows that one of the world’s fastest growing economies is a disaster on the environmental front.



What’s worse, India’s pollution levels could be playing havoc with the health of its citizens. “A bottom performer on nearly every policy issue included in the 2014 EPI, with the exception of forests, fisheries and water resources, India’s performance lags most notably in the protection of human health from environmental harm,” said a statement issued by Yale.
The study described India’s air pollution as the worst in the world, tying with China in terms of the proportion of population exposed to average air pollution levels exceeding World Health Organisation (WHO) thresholds.
A deeper look at the data gathered by a Nasa satellite showed that Delhi had the highest particulate matter 2.5 pollution levels followed by Beijing. Delhi, with 8.1 million registered vehicles, has repeatedly beaten the Chinese capital on particulate matter pollution.
The high PM2.5 pollution caused by high vehicle density and industrial emissions is the reason for the dense smog that has been engulfing Delhi during the winter months in the last few years, with adverse health implications. And while Beijing’s infamous smog has hogged headlines and prompted government action, even led to the announcement of rewards for cutting back on pollution, the dangers in Delhi have been largely ignored.
According to a study by the Harvard International Review, every two in five persons in Delhi suffer from respiratory ailments. The Lancet’s Global Health Burden 2013 report termed air pollution the sixth biggest human killer in India. The WHO last year termed air pollution carcinogenic.
Particles smaller than 2.5 microns in diameter (PM2.5 in shorthand) are fine enough to lodge deep in human lung and blood tissue and cause diseases ranging from stroke to lung cancer, the Yale study said.
Anumita Roy Chaudhary, executive director of Delhi-based advocacy group Centre for Science and Environment, said policy-makers have failed to take the kind of action needed to check phenomenal growth in air pollution in India. “The gains of the introduction of CNG in 2000 have been lost. We are heading for dark days if policy-makers fail to wake up to the growing environmental health hazard,” she said.
The Central Pollution Control Board’s report of 2011 said only two cities, Kochi and Coimbatore, met the national ambient air quality standards, which are six times higher than WHO standards. Air pollution in half of the 280 Indian cities monitored has been termed critical or hazardous for human health. “Air pollution levels in almost all cities are on the upward trend,” said a CPCB scientist.

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How Leaders Should Communicate 2014 Business Goals

by Sharlyn Lauby | Posted January 7^th, 2014 | Communication

Happy New Year! If you’re like most people, you might have made a few resolutions or set a couple goals for 2014. Now, the challenge becomes accomplishing those goals.
Organizations go through the exact same thing. They set goals and then need to ensure those goals are met.
One reason organizational goals aren’t realized is because they weren’t communicated properly. Here are the steps you can take to communicate your business goals effectively to the entire organization.

Include stakeholders in the goal-setting process

One of the best ways to get buy-in is to include people in the process. Allow the employees most impacted by the goal to have a say. For instance, if your company is planning to implement a Bring Your Own Device (BYOD) policy in 2014, the technology department will be affected by this decision. So you should include members from the technology team in establishing the specifics for this goal.

Dedicate the time to set business goals

Don't take the process of setting goals lightly. When an organization creates a goal, they' also saying this goal is a priority. Why set a goal for something that isn’t a priority? The company should manage their priorities carefully because not everything can be a priority.
Many times, the goal-setting process is linked to budgets or annual performance reviews; but really, goal-setting can take place at any time.

Make sure goals align with the business and each other

When it comes to the point of actually conveying goals, think about presenting them in a logical format. The last thing anyone wants is for one goal to challenge another. Or — even worse — for a goal to contradict a company policy.

Address business goals that are no longer a priority

The business world is constantly changing. It’s likely that goals we set in the past are no longer relevant. It could be because a goal has been accomplished. For example, a company sets a goal to reduce turnover by 10%.
Once accomplished, the company is able to celebrate its success. Ah, but is it really something to celebrate if the goal is no longer essential for business success? If this is the case, leaders must then communicate the change in priorities to employees.

Talk about business goals in two ways: new and revised

Brand new goals should be singled out and discussed at length. This is an important step because employees are not familiar with them. Leaders should explain not only the specifics of these goals but why they're a focus for the organization. Similarly, remaining business goals should also be reviewed, particularly if they have been revised in some way; leadership needs to provide employees with an explanation of the changes.

Explain how and when goals will be measured and reported

Every business goal needs to be measured. Otherwise, why have them? When leadership explains each goal, they need to share the measurement of success and the method for collecting the data. I once worked for a company that maintained a board with our success metrics; it was placed just inside the employee entrance.Every day, employees could see how the company was doing compared to its goal. Employees told us this visual of our company’s success metrics was a great motivator.

Allow employees to ask questions

After providing a thorough explanation of the company’s goals, take time to field some questions. Employees might want further clarification. Don’t make the assumption that questions mean employees aren’t in favor of the goals. Questions can be a good sign that employees are engaged and interested. The discussion lets you know they understand.

It's never too late to communicate business goals

If you’ve already completed your goal-setting exercise and missed one (or more) of these steps… no worries. You can go back and close the loop.
Let’s use the first example, the BYOD policy. Suppose you forgot to bring technology into the conversation. To fix the matter, have a meeting with the technology team, apologize for not bringing them in the loop, and ask for their feedback.
Or if you didn’t identify the goals that are no longer a priority, at the next staff meeting mention that you want to take time to explain the reason certain goals will not be at the top of the priority list in 2014. This could be a great time to acknowledge the accomplishment of goals from previous years.
The important step is to communicate. Employees who know all about the goals of the organization can have focus and a positive impact on achieving those goals.