SAFETY TRIP VALVE FOR STEAM OR GAS TURBINES WITH MEANS TO ASSURE CONTROLLED OPENING FROM THE ED POSITION

摘要

1503243 Valves TURBODYNE CORP 14 Jan 1976 [19 June 1975] 01435/76 Heading F2V [Also in Division G3] A safety trip valve for interrupting the flow of working fluid to a turbine, is automatically closed on the occurrence of adverse working conditions (see Specification 1,281,408) but cannot re-open when the adverse conditions are corrected until an auxiliary valve is actuated by mechanical means. The valve is shown in its normal operative position permitting fluid flow from inlet 23 to outlet 25. Adverse conditions cause a lever 13 to open a pilot valve 11 and vent a chamber 42 below piston 34 via line 12 and adjustable throttle 14. This causes the main valve 33 to be moved into engagement with its seating 27 by inlet pressure communicated to the chamber above the piston 34 via orifice 68 and passages 67, 69, 71. Once the main valve is seated the orifice and passages instead communicate with the outlet but the chamber above the piston still receives inlet pressure fluid via an exposed port 50, passages 48, 49 and passages through auxiliary valve 56 which is then forced open by the incoming fluid pressure. The main valve is maintained in its closed position even if the pilot valve 11 is subsequently closed causing the chamber 42 to be re-pressurized via clearance 39, because the lower surface of the main valve 33 is still only subjected to outlet pressure. Thus it is necessary to screw-down rod 80 sufficiently to engage and close the auxiliary valve 56, causing the upper chamber to bleed down to outlet pressure via orifice 68 and passages 67, 69, 70 and thereby create sufficient pressure differential across piston 34 to overcome the oppositely-acting pressure differential across the main valve 33. However, the main valve can only open at the rate allowed by the subsequent upward movement of the abutting rod 80 thereby providing a controlled re-opening. The adjusted rod 80 can be used to locate the main valve in any position intermediate its closed and fully open positions without detriment to the safety functioning of the valve.