Boiler Water Treatment
The water used for boilers usually contains various substances such as suspended solids, dissolved solids and gases. When used directly such raw water results in problems such as scale, corrosion, carryover, etc. in the boiler and accessory equipment. In low pressure boilers usually there are problems of hardness and silica scale and corrosion due to dissolved oxygen throughout the system and corrosion due to carbon-dioxide in the condensate line. In medium and high pressure boilers, metal oxides are deposited on the heating surface, corrosion of accessory and scale problem in the superheater and turbines, etc.
Deposits directly reduce heat transfer, causing higher fuel consumption, high metal temperatures and eventually failures. Corrosion not only results in failure at the point of attack, but also produces serious levels of metal oxide contamination, which in turn may cause deposits elsewhere. Carryover results in superheater turbine and condensate system deposits, corrosion and/or erosion problems.
Therefore the three main objectives of a boiler water treatment program are to:
- Prevent formation of deposits
- Reduce corrosion of metals
- Prevent boiler water carryover
Boiler Compounds Boiler compounds have two functions: preventing scale formation and adjusting pH of boiler water to inhibit corrosion.
Treatment with phosphate based boiler compoundsPhosphate base boiler compounds contain Phosphate and alkali agents. Both these compounds prevent scale formation by reacting with hardness components (Ca&Mg) and converting them into suspensible substances and by keeping silica substances water soluble.
Treatment with non-phosphate based boiler compounds includes polymers and chelating agents.
Oxygen ScavengersOxygen scavengers viz sodium sulfite, Hydrazine, etc remove dissolved oxygen in water by a reduction reaction. CAWTL�s patented product Mekor 70 passivates metal surfaces through the formation of magnetite and cuprous oxide films, minimization of iron and copper deposits in the boiler and ability to provide corrosion protection to after boiler sections of the system.
Corrosion protection in boilers is achieved by neutralizing and filming amines. Neutralizing amines inhibit corrosion by controlling the condensate pH. Filming amines form a water repellent film on metal surface which prevents direct contact with the corrosive substances like oxygen and carbon-dioxide.
Oxygen Scavengers
Kem BLR 10
Kem BLR 100
Mekor 70
Amerzine 35
Steam condensate corrosion inhibitor
Kem BLR 17
Kem BLR 32
Amercor series
Mekor 70