GB770651A - Improvements in or relating to turbine control mechanisms - Google Patents

Abstract

770,651. Turbines; centrifugal pumps. SCHELLENS, C. A. Jan. 11, 1954, No. 733/54. Classes 110 (1) and 110 (3). [Also in Group XXIX] Control mechanism for regulating the supply of liquid or gaseous working fluid to a turbine comprises a valve member arranged so as to be subject in all its positions to a substantially constant closing bias produced by the pressure of the working fluid and having a protruding stem engaged by a member opposing the closing bias and responsive to changes in power demand on the turbine by the device driven thereby. As shown, the valve 25 controlling the passage of steam &c. to the turbine is a double beat valve constantly biased towards closed position by inlet pressure admitted to a chamber 28 through a passage 30 and opened by a singleacting servomotor 32 of which the control valve 36 is connected to a floating lever 44 which has a follow-up connection with the piston rod 33 and is also connected to a lever 48. At one end the lever 48 is linked to a plunger 51 subject to delivery pressure of a rotary pump driven by the turbine, and at the other end is connected to an overspeed centrifugal governor 9. The plunger 51 controls the main valve 25 so as to maintain a constant delivery pressure from the pump, whilst the governor causes the main valve to be closed in the event of overspeeding. Instead of the plunger 51, a temperature or other pressure responsive control may be used. The motive fluid for the servomotor is obtained from a lubricating pump 13 driven by the turbine so that a failure of lubricating oil pressure shuts down the turbine. The main valve may be shut by a hand-wheel 19 through which passes a threaded stem 18, the lower end of which engages the stem of the valve and closes the passage 30. A modified valve 25 is of singlebeat form with a partially balancing piston.