Treatment of silica-limited cooling water. Volume 3. Appendixes. Final report

Silica condenser scaling can affect overall power plant heat rate, lead to plant outages, and significantly reduce condenser tube life. Furthermore, unlike calcium carbonate and calcium sulfate scaling, silica scaling cannot be prevented by using chemical additives in the cooling system. Therefore, plants that use a high-silica makeup water for the cooling system typically operate well below the accepted guideline of 150-ppM silica in the recirculating water. The results of field testing at the North Valmy station, however, indicate that this guideline may be very conservative and that operation as high as 260 ppM for short periods of time should not lead to condenser scaling. The test results prove that silica can be effectively removed with makeup or sidestream softening and illustrate the importance of certain operating parameters, such as magnesium chemicals addition. The Sierra Pacific Power case study also validates the use of EPRI computer models CLGTWR and DRIVER and the Cooling-Water Treatment Manual to define cooling-system operation and chemistry. Volume 1 of this report presents the results of those field tests. Volume 2 presents the results of research conducted in support of the field tests. The support studies included the following activities: literature search, utility survey, laboratory studies,more » computer model development, and design exercises. Volume 3 is a set of appendixes presenting all of the field test data.« less