Alkaline Sequestrant Boiler Technology

Boiler water is treated to control corrosion, prevent scale, and reduce deposition throughout the boiler system. Historical chemistry to control hardness scale formation had evolved from early carbonate cycle treatment to phosphate cycle chemistry by 1950’s. These were precipitating chemistries, hardness added by feedwater was precipitated as solids which could form a sludge on heat exchange surfaces and required higher blowdown rates. Chelants were introduced in the 1960’s as an improvement as the hardness ions were kept in true solution.

Unfortunately, all three chemistries are stoichiometric, the amount of regent added has to exceed the amount of hardness entering the boiler in the feedwater.

ProChemTech has developed alkaline sequestrant chemistry to address the problems of sludge, excessive blowdown, and high cost. Alkaline sequestrant chemistry utilizes phosphonate to convert hardness ions into micron sized particles. These particles are distorted by the phosphonate and thus do not grow beyond micron sizes. Polymers are incorporated into the products to keep the particles dispersed preventing sludge formation and ensuring effective removal via minimal blowdown.

Alkaline sequestrant chemistry is sub-stoichiometric, the amount of reagent needed to prevent scale formation is much less than the amount of hardness ions. Thus, alkaline sequestrant chemistry is more economical than older technologies. As this technology does not require high levels of OH alkalinity to be present higher cycles, less blowdown, can be obtained with high alkalinity makeup waters.

Control testing of our alkaline sequestrant products has been simplified by use of a molybdate based tracer with control levels of 1 to 2 mg/l as Mo.

Alkaline sequestrant chemistry is approved for use in food plants by the USDA.