| 摘要 |
1529935 Steam turbines BBC BROWN BOVERI & CO Ltd 13 Oct 1976 [15 Oct 1975] 42509/76 Heading FIT [Also in Division F4] In a steam turbine installation, when the load on two-stage turbine 4, 6 is dumped a safety and regulating device 11 calls for closure of governor valve 3 and interceptor valve 7 via signals 14, 16, and if valve 3 fails to close then logic circuit 27 responds to the disparity between signal 14 and a signal 26 from a sensor 25 monitoring the pressure drop across stage 4 of the turbine and after a delay of 0.2-0.5 secs the circuit trips device 11. Upon being tripped, device 11 calls for closure of stopvalves 2, 8 and partial opening of vacuum break valve 20 via signals 12, 18, 21. If valves 2, 8 close, then valve 20 is reclosed after the vacuum has been lowered a small amount. If, however, sensor 25 still detects a pressure differential 1-5 secs after device 11 is tripped then the circuit 27 provides a signal 29 which serves (a) to fully open the vacuum break valve 20, (b) to open valve 34 to admit water to cooling nozzles in the second stage of the turbine, (c) to close down the steam generator (51) which may be part of a nuclear power plant. The device 11 may also be tripped by sensors monitoring other parameters, e.g. bearing temp. A second logic circuit 37 is included which receives signals 16, 18 and a signal 36 from a sensor 35 monitoring the pressure drop across the second stage of the turbine and which responds similarly to circuit 27 if valves 7, 8 fail to close. |
