Water/Steam Treatment Programs and Chemistry Control for Heat Recovery Steam Generators

New power generation in the U.S. is being dominated by installation of combined-cycle power plants, where a significant portion of the power is produced from steam turbines supplied by heat recovery steam generators (HRSG). Proper chemistry control and monitoring of HRSG feedwater, boiler water, and steam are essential for high reliability and availability of these units. However, many plants have minimal staff, most if not all of whom have no formal chemistry training and who may not fully understand the importance of water/steam chemistry and monitoring techniques. This paper provides an outline of the most important chemistry control methods and also examines the phenomenon of flow-accelerated corrosion (FAC). FAC is the leading cause of corrosion in HRSGs,[1] and is often the result of the outdated belief that oxygen scavengers are a requirement for feedwater treatment. Since 1986, FAC-induced failures at several coal-fired power plants have killed or injured a number of U.S. utility workers.