This section is for High pressure boilers only (over 45 bar). For boilers till 65 bar click here

High Pressure Manual

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High pressure boilers require the use of feedwater having a high degree of purity to ensure high operational reliability. The impurities or chemical species that might be present in boiler feedwater are removed with the use of demineralizers, mixed bed polishers or other techniques in order to purify the feedwater prior to introduction into the boiler. 

The purity standards allow a maximum feedwater hardness of only 0.1 ppm or less. Such boilers are often, but not necessarily not only high pressure, but also high heat transfer rate boilers, that can tolerate almost no solids internally.

When a boiler's feedwater routinely meets such high purity standards, the internal chemical program of choice is normally a pH/phosphate control program (sometimes known as a coordinated or congruent phosphate control program), optionally together with a dispersant treatment.

Dissolved oxygen has also to be removed, and especially care has to be taken to other corrosion related factors, such as HRSG corrosion fatigue, flow accelerated corrosion (FAC),   etc.

Steam and condensate treatment is also important in high pressure boilers, as to protect expensive equipment, like steam turbines, to reduce maintainance cost, and to insure that no corrosion products will return to the steam generator, leading to overloads in polishers and possibility of system;s faillure.

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