GB1072051A - Improvements in or relating to control systems for vapour generating installations - Google Patents

Abstract

1,072,051. Steam turbine plant. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Jan. 26, 1965 [Jan. 27, 1964], No. 3411/64. Heading F1T. In a method of controlling the starting up of a vapour generating and superheating unit arranged to supply vapour to a turbine, the temperature of superheated vapour flowing to the turbine is regulated in such a manner that the difference in temperature between the vapour and the turbine casing is maintained at a predetermined value. In the embodiment shown the steam generator comprises steam generating tubes disposed around the furnace 3, a primary superheater 11 and a secondary superheater 13, also a first and secondary steam reheater 15 and a primary steam reheater 17. A steam attemperator 35 is disposed between the primary superheater 11 and the secondary superheater 13. The steam discharging from the secondary reheater 15 passes through an attemperator 41, the attemperator 41, also attemperator 35 being in the form of water spray devices. Superheated steam from the superheater 13 passes through line 37 to the inlet 23 of the high pressure steam turbine 21, the steam from which passes through line 39 to the reheaters 17, 15 then through line 43 to the inlet 27 of the low pressure turbine 31, the steam discharging from the turbine through outlet 29. The temperature of the superheated steam in line 37 is measured at 45 and a signal indicative of this temperature is transmitted to the comparator 53. The temperature of the high pressure turbine casing 21 is measured at 49 and this temperature is also transmitted to the comparator. In the event of these temperatures differing by more than a predetermined amount a signal is transmitted to the valve 63 which controls the rate of flow of water to the attemperator 35 whereby the temperature of the steam passing to the line 37 is reduced. Similarly the temperature of the steam in the reheat steam line 43 is measured at 47 and the temperature of the low pressure turbine casing 31 is measured at 51 and signals indicative of these temperatures are transmitted to the comparator 55. Should the temperatures differ by more than a predetermined value the regulating valve 65 is actuated so as to increase the flow of water to the attemperator 41 so reducing the temperature of the steam passing through reheat line 43. The values of the predetermined temperature differences are controlled by a digital computer 57 and the values may vary during the start-up operation.