Steam Power – Water Cycle In Boilers

Steam power - water cycle In steam boilers

Steam boiler at a power plant
Steam boiler at a power plant

High purity water for steam boilers
Power generation plants vary widely in size but most power plants share the same requirements for pure water. Raw water enters the power generation plant and is purified through several stages of filtration and demineralization.

This continuous stream of purified water becomes the steam boiler feed water. The boiler generates steam that drives the turbines to generate electricity. Some of the steam is also used to preheat the high purity boiler feed water. Ultimately, the steam is collected as condensate, mixed with pure make-up water, preheated and recirculated as steam boiler feed water.

Unfortunately, high purity water is corrosive to steam boiler and condensate systems. In addition, leaks in the system can add unwanted chemicals that increase corrosion potential. For example, in the condenser, raw cooling water can leak into pure water.

To counter these effects, trace level corrosion inhibitors and oxygen scavengers are typically added to the steam boiler feed water to reduce these risks. Effective chemical treatment of the boiler feed water is critical to maintaining the steam boiler and condensate systems and protecting the capital investment of the power generation facility.

Rather than determining corrosion occurrence over a period of time using an outdated technique, corrosion can now be monitored like any other process variable (i.e., pressure, flow, level, temperature, pH) by the power plant operator.

Steam condensate reclamation 
Steam is used in almost all industrial boilers. Steam generated in the boiler plant is transferred to the various facilities in different pressure ranges. As energy is consumed from the steam, condensate is formed, and returned to the steam boiler plant for reuse. Steam in the boiler plant is produced from water of very high purity.

Steam condensate application challenge
Steam condenstate is collected and returned back to the boiler. It needs to be re-treated as it often acquires particulates that will cause scaling, pitting, or corrosion of the boiler tubes. Unless this condition is corrected, the steam boiler will need to be rebuilt, with extensive downtime and high costs. 

Steam condensate application solution
Depending on the size and type of steam boiler, CorrTran MV corrosion monitoring should be installed in a location that is most susceptible to corrosion. CorrTran MV evaluates both general and localized (pitting) corrosion, as well as conductivity, in the same industrialized transmitter housing.

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