Internal Treatment Programs

Chapter 11 completes the discussion on internal treatment programs with information on program primary support chemicals, including oxygen scavengers and condensate treatments (vapor phase inhibitors) and adjuncts. 

The various formulatory raw materials necessary to produce these programs are available as either commodity, semispecialty, or specialty chemicals worldwide. Although today all water treatment companies, no matter their size or location, have virtually the same opportunities for materials sourcing, some depth of experience is required to provide blended (and branded) products that have genuinely beneficial properties and the potential for competitive differentiation. 

In addition, it should be stressed that all these functional products and their various chemistries are merely tools to be employed in the operational management and maintenance of boilers and BW surfaces. To maximize the potential benefits available, these BW treatment programs must be utilized in the most suitable way, which in turn requires  

There is no substitute for proper training and experience in the application of BW programs. Both operators and service company field personnel must be able to demonstrate competence so that the potential for added value is realized. 

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In addition, attention must be paid to the BW internal treatment program. Such programs involve the dosing of small amounts of polishing chemical treatments to specified points in the water-steam cycle system, often continuously and proportional to water flow or steam demand, to provide a desired inhibitory or protective effect. 

Where phosphate is used for internal treatment programs, a variety of insoluble phosphate and hydroxide salts are produced to form sludges. If these sludges are not properly held in a suspension by the use of appropriate polymeric dispersants (and then blown down from the boiler within a certain period), they will deposit on heat exchange surfaces as hard, adherent scales. 

NOTE In lower pressure FT and WT boilers, internal treatment programs using phosphate are common and a small phosphate reserve is permanently maintained. 

For all LP steam operations in which the total hardness of RW exceeds, say, 10 to 20 ppm CaC03, the use of a softener is preferable to control solely via internal precipitation treatment. Oxygen scavenging and other internal treatment programs should also be provided. Some MPHW/HPHW and lower pressure steam boiler designs may require additional purification beyond simple water softening. 

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