ChemTreat has a full portfolio of chemicals for water treatment that use chelants to prevent the precipitation of boiler feedwater contaminants that would otherwise lead to fouling. Chelation depends on sequestration whereby chemistries bind ions like calcium, magnesium, and iron and keep them in a soluble state. Cleaner boilers can often be achieved with chelants than with any form of precipitating treatment. However, chelants are usually more expensive than phosphate programs since they react on a mole-to-mole basis. Furthermore, the control and subsequent testing requirements for chelation are more stringent and demanding than for phosphates.
Since the predominant chelation reactions take place in the boiler feedwater and not in the boiler water, considerable care must be given to selecting the proper chemical feed points. ChemTreat field engineers are experts at applying chelant technologies to any boiler water system.
Because complete chelation is theoretically never attained, ChemTreat incorporates polymeric dispersants in all chelant-based programs to assist in preventing iron and mineral deposition.
Chelant treatment programs have the following requirements:
- Dissolved oxygen levels below 25 ppb.
- Removal of calcium and magnesium to below 0.5 ppm as calcium carbonate.
- Removal of silica and/or alkalinity from the makeup water.
ChemTreat programs are relevant for the following applications:
- When plant steam production and operating requirements preclude the use of a precipitating program.
- Boiler design prevents the use of phosphate treatment.