Coagulation and Precipitation Program Chemistries

almost all internal programs of this type employ a combination of some type of phosphate plus caustic soda, although sodium carbonate (plus caustic) is still occasionally employed for smaller process boilers receiving poorer quality, hard water MU. 

Soda ash (sodium carbonate) is less expensive than phosphate and so tends to be used as a BW treatment in some developing countries for basic industrial processes such as mashing of farm products for animal foods, palm oil extraction, rendering plants, tanneries, and textile washing and dyeing. Often there is little or no condensate return. 

Before the advent of sophisticated polymer technology, sodium alu-minate and sodium silicates (plus caustic) were sometimes used in both external and internal coagulation processes. 

1 Alkaline Aluminate and Silicate-Based Boiler Compounds 

Boiler compound formulations containing aluminate, silicate, and carbonate ingredients have commonly utilized various ratios of some or all of these constituents, together with caustic soda (for alkalinity control), sodium nitrate or sulfate (to prevent caustic embrittlement), sodium lig-nosulfonate (sludge conditioner), and other compounds. 

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