A connection between cycle chemistry and condenser configuration: part II
Air in-leakage into the steam space of a condenser can become stored in pockets of high partial pressures that negatively impact condenser performance and become a source of dissolved gases in the feedwater. These pockets can be configuration caused and generally cannot be eliminated by reducing air ingress or increasing venting capacity. Fortunately, engineering designs are available to eliminate or significantly reduce the size of these pockets. Dissolved gases in condensate also result from air ingress below the water level in the hotwell on through to the suction side of the condensate pump. This paper reviews mechanisms responsible for the dissolubility of these gases and the unique and complex relationship between carbon dioxide gas and water under the sub-atmospheric pressure conditions of the condenser environment. The results of an engineered design retrofit of a poorly operating condenser are discussed showing the elimination of excess condenser pressure and recognized dissolved gases in condensate. Measured data from air introduced into the condenser at NIPSCO Michigan City Generation Station (MCGS) will be shown in a way to highlight the difference in how oxygen and carbon dioxide gas become incorporated into the condensate. Lastly, the impact of dissolved carbon dioxide on the performance of a Powdex polisher is assessed based on measured data.