Alternative means of ambient temperature deoxygenation during unit startup or outage
- Southern California Edison Co., Paramount, CA (United States)
During normal operation of a fossil-fueled generating unit, the desired level of oxygen in high purity feedwater is determined by the mode of operation. For all volatile treatment (AVT), <1 ppb oxygen has been the goal, whereas for oxygenated treatment (OT), 50-200 ppb oxygen is typical. Regardless of the mode of normal operation, deoxygenated water is generally required during startup of a unit because of the presence of contaminants. In the absence of condensate or steam supplied by an on-line unit or an auxiliary boiler, oxygenated make-up water may be all that is immediately available to fill the boiler and/or pre-boiler system. Given the current trend towards increased cycling of units and more frequent cold plant start-ups, the requirement for rapid deoxygenation at ambient temperature is expected to increase, challenging those responsible for water treatment and chemical control to meet the need as economically as possible. Although there are a number of processes that can be used for deoxygenating makeup water, most of them require additional equipment (such as a vacuum deaerator or carbon bed) or extensive modifications of the existing demineralizer system (e.g., to allow use of sulfite form anion resin). In addition, distilled water storage tanks would need to be protected from reintroduction of oxygen. A simple, inexpensive, rapid, and flexible means of deoxygenation at ambient temperature that can be used as part of a makeup water system or to process deionized water in condensate tanks, boiler, or the deaerator storage tank would enable stations to deoxygenate as needed. Circumstances within the Southern California Edison (SCE) system forced us to look more critically at existing means of deoxygenation; our efforts resulted in the eventual development of the simple, inexpensive, rapid, and flexible ambient temperature deoxygenation process sought.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 50716
- Report Number(s):
- EPRI-TR--104502; CONF-940982--
- Country of Publication:
- United States
- Language:
- English
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