The Thermal–Hydraulic Design of Main Feed Water Pump Suction Systems for Large Thermal Power Plant

Abstract

British domestic design practice is described for boiler feed pump suction systems associated with high level deaerator/feed water tanks in large modern power plant. The objective of thermal–hydraulic design is the provision of adequate pressure to boiler feed water pump suctions under all transient and steady state conditions to ensure continuity of water flow and reliable pump operation. Methods are available for the determination of pressure decay in feed tanks during load transients, but the successful application of mathematical relationships between pressure decay and pressure rise in suction pipework depends on the correct identification of operational circumstances. Progress in recent years has been on the identification of circumstances which produce governing conditions and has taken design practice beyond the stage established by early workers. Developed practice has been successfully applied by the Central Electricity Generating Board and its main plant contractors to forty-nine 500 MW units in coal- and oil-fired stations and to twenty-three 660 MW units in coal, oil and advanced gas-cooled reactor stations, which at 39 680 MW, constitutes the major proportion of plant in England and Wales. Aspects of plant behaviour and operation crucial to successful system design are featured. Recommendations are made for plant layout, pipework routing, tank outlet and pipework sizing, net positive suction head (NPSH) determination etc.