GB856323A - Improvements in or relating to regulating arrangements for steam power plants including a steam boiler having low storage capacity - Google Patents

Abstract

856,323. Steam power plant; turbines. SIEMENS-SCHUCKERTWERKE A.G. July 29, 1957 [July 28, 1956; March 22, 1957], No. 24016/57. Classes 110 (3) and 122 (3). In a steam power plant including a boiler 7 of low storage capacity and a cold condensate accumulator 10 the boiler and the prime mover are regulated according to the prime mover load by a system including means for controlling the supply and discharge of condensate to or from the accumulator in accordance with both the water level in the accumulator and the prime mover load. The boiler 7 supplies live steam via a pipe 9 to a turbine having H.P. and L.P. stages 1 and 3 respectively interconnected by a reheater 2 and driving a generator G. The turbine exhausts to a condenser 17 from where condensate is pumped by a pump 15 through a valve 43, controlled by a regulator 42, and the L.P. stages 35 and 36 of a regenerative heating system to the feed water tank 37. Feedwater is drawn from the tank 37 by a pump 38 controlled by a device 6<SP>1</SP> and discharged through an H.P. stage regenerative heater 39 to the boiler 7. The turbine steam inlet valve 4 and, via a regulator 5, the boiler load setting device 6 and feed pump control device 6<SP>1</SP> are controlled according to the turbine load by signals such as, for example, a generator speed impulse n, a generator fre. quency or power output impulse e, or an impulse h applied manually or according to a time-table regulating device. In the event of a sudden load change regulators R<SP>2</SP> and R<SP>3</SP> operate to falsify the turbine load control signal at the turbine valve 4 and thereby delay bringing the turbine to the new operating condition until the boiler has adapted itself to the new load. The height of the water level in the cold condensate accumulator 10 is maintained by a device 11 and regulator 12 controlling discharge and supply valves 13 and 14. The regulator 12 is also subjected to the pressure in the live steam pipe 9 through an impulse line g so that variations in the steam pressure apply an additional impulse to the regulator 12 thereby simulating or effecting a deviation of the water level in the accumulator 10 and increasing or decreasing the discharge of condensate therefrom as the steam pressure falls or rises. When the boiler and turbine are operating at the new load after a sudden load change the boiler is subjected to an additional influence through an impulse line i so that it runs at an excess or decreased load until the normal water level in the accumulator is restored. In a modification, Fig. 2 (not shown), the valve 13 is connected to the pipe 18 and the condensate from the accumulator is returned to the boiler with the condensate from the condenser 17 by the pump 15, the pump 19 being omitted if desired. In a further modification, Fig. 4, the condensate supply or discharge line 40 for the accumulator is connected in the pipe line between the condenser condensate pump 30 and a condensate pump 22 driven by a motor 21 whose speed is controlled by the level regulator 12. A limiting device 23 and a setting device 24 are included in the impulse line g so as to control and limit the speed of boiler load variation. In a further modification, Fig. 5 (not shown), the output of the pump 22 is controlled by adjustment of a valve on the delivery side of the pump controlled by the regulator 12.