Effects of a Load Reduction on the Feed System of the Feed Pump.

With sliding pressure operation preferred today in large power stations it must be ensured that even with an extreme load reduction following a turbine trip or load shedding no cavitation occurs in the feed pipework and/or the feed pump. Using a computed example, it is shown how the boundary conditions - form of intake of feed pipework, transient response of the condensate and feedwater flow and of the condensate temperature, determination of the reference levels - influence the coordination of the actual and the permissible rate of pressure drop. The results are compared with measured values and with methods of monitoring. Protective measures of standby feed pumps are cited.