GB1381908A - Feed and injection water control for steam generators - Google Patents

Abstract

1381908 Steam generator control E PRITCHARD 26 April 1972 [30 April 1971] 19439/72 Heading F4A A steam generator control system comprises a steam generator 10, a burner 31, a coil 18 supplying superheated steam to a steam-powered apparatus 11, a water injection circuit 51 in parallel with a section of the coil 18 and including a valve and metering means, and a feedwater supply pump 16 arranged normally to supply feedwater at a rate less than the requirements of the generator but able to supply an increased flow when there is flow in the injection circuit, and a rotary motor 24 powered by exhaust steam and controlling the feedwater supply. Normally the feedwater is supplied by pump 16a, but when the temperature indicated by superheater thermostat 14 rises above a first level solenoid 43 is energized and water is supplied by a second pump 40; at the same time a valve in the circuit 51 is opened, unless thermostat 27 indicates overheating in the bypassed part of the coil. If thermostat 14 detects a temperature in excess of a second level, greater than the first level, or if switch 53 detects an excessive superheater steam pressure, than the burner is switched off. The motor 24 is bypassed by a valve, Fig. 6 (not shown), having a spring- biased piston (61) which allows passage of excess steam, so that the motor speed does not become excessive at high pressures. Or the motor may be retarded by motor/generator 56 which cuts in to act as a generator and thus impose a torque load, and which acts as a motor at start and at low speeds.