Moisture-separator-reheater drain cooler system

Abstract

A steam turbine system has a plurality of moisture-separator-reheaters (MSR) each connected via a respective drain line to a corresponding drain receiver. Each drain receiver includes a further drain line coupled through a flow control valve to a common line. The common line empties into a drain cooler connected at the highest pressure end of a series of feedwater reheaters. The drain cooler dumps through another flow control valve to one of the feedwater heaters. Each of the drain receivers includes a pressure sensor and liquid level sensor. A control processor monitors the pressure sensors and selects the drain receiver subjected to the lowest pressure. The processor then fully opens the valve associated with the selected drain receiver and thereafter regulates the liquid level in the others of the drain receivers by adjustment of their respective flow control valves in response to their respective level sensors. The liquid level in the selected drain receiver is adjusted to its preselected level by control of the flow control valve connected to the drain cooler. The pressure in the common drain line is regulated to the pressure at the lowest pressure drain receiver by adjustment of the control valves associated with the other drain receivers.