“A Voyage on the Seven C’s—Condenser Configuration Caused Cycle Chemistry Corrosion Calamities” EPRI International Conference on Cycle Chemistry, Calgary, Canada, June 20-22, 2006.
Cycle chemistry issues have, at their origin, a cause that gives rise to an effect, initiating a need for chemical treatment. Corrosion, corrosion byproduct deposition and other deleterious results of contaminants entering the steam and water cycle require chemical treatment to mitigate the consequence of their presence. It is recognized that recycled condensate accumulated in the condenser hotwell contains most of these undesirable corrosive species. Specifically, these are dissolved noncondensable gases from air in-leakage into the condenser, decomposition products throughout the cycle, and a wide range of contaminants from cooling water in-leakage. This paper will be limited to discussing the source and cause of dissolved gases in condensate, how this effect may be minimized or eliminated, the need for chemical treatment and the benefits of reducing chemistry upsets. The presented information is equally applicable to condensers and low pressure components found in fossil, nuclear and combined cycle plants.
To be discussed is the need to continuously monitor the condenser for noncondensable gas removal rate and to maintain its value below a recently well defined level such as to maintain optimum condenser performance and minimize dissolved gases. Notwithstanding this allowed level of air in-leakage and the admission or production of other noncondensable gases into the shell space, condenser tube bundle configurations can contribute to elevating the amount of dissolved gases in condensate and harmfully affect measured performance indicators. Methods to diminish or eliminate these contributing configurations and to reduce the criticality of water treatment are available; these will be outlined.
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