Silica fouling/scaling control

Fig. 16.3 gives the flow sheet of a cooling water system commonly used in power generation that is also used in the process industries. Chemicals such as acids, biocides, scale and corrosion inhibitors and dispersants are added to control problems of fouling in the recirculating system (described elsewhere in this book). The technique is generally applicable where the make-up water is generally of low hardness and silica and low concentration factors are employed. 

Water-side deposits are of many types. Hardness (calcium and magnesium)-based deposits and iron oxide are the most common water-side deposits and often affect boUers and cooling systems. Process and oil leaks can foul boilers and cooling systems. BiofouUng, mud, and debris are often found in cooling systems. Treatment chemicals, if not properly controlled, can add to deposits and scales. Silica can form hard, adherent deposits in boUers, steam turbines, and cooling systems. Corrosion products can add to deposits. 

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