GB757293A - Steam power plants employing forced flow steam generators - Google Patents

Abstract

757,293. Steam turbine plant. SULZER FRERES SOC ANON. Dec. 10, 1954 [Dec. 10, 1953], No. 35769/54. Class 110(3) In a steam power plant comprising a forced flow steam generator working at a pressure of the order of 150 atmospheres or above feeding steam to a turbine having high, intermediate and low pressure turbines with reheaters between the high and intermediate pressure and the intermediate and low pressure turbines, the reheaters being heated by steam before it enters the high pressure turbine, has the heating steam sides of the reheaters connected in parallel to common steam supply and return pipes. The condensate pump 2 draws condensate from the condenser 1 and delivers it through feed water heaters 4, 5, 6 into the feed tank 7. A feed pump 8 draws water from the tank 7 and delivers it through feedwater heaters 10,. 11, 12 to the steam generator 13. The steam leaving the superheater 14 flows through pipe 15 to pipes 16, 17 leading to the reheaters 18, 19. The first ports 18a and 19a i.e. those subject to high temperatures of the reaheaters are made of austenitic steel and later' ports 18b 19b of ferretic steel. After leaving the reheaters the steam is re-united in a conduit 20 through which the steam flows into the second superheater 21 and thence through a. steam valve 22, a valve 24 and a quick acting stop valve 25 to the high pressure turbine 26. After partial expansion in the turbine 26, the steam is reheated in the reheater 18 and then passes through valve 28 to the intermediate pressure turbine 29. After further expansion in the turbine 29, the steam is reheated in the reheater 19 and expanded in the turbine 32 which exhausts to the condenser 1. Steam is bled from the turbines by means of the pipes 35 and led to the feed water heaters 4, 5, 6, 10, 11, 12 and the feed tank 7. The drains from the heaters 10, 11, 12 are led back to the feed tank and those from the heaters 4, 5, 6 back to the condensers. To adjust the temperature of the reheated steam by-pass pipes 38, 39 with control valves 40, 41 are provided. A valve 42 is also provided in the return from the reheater 19 to control the division of steam between the reheaters. In order to accelerate the starting process, a turbine by-pass 44 together with a control valve 43 is also provided. The invention is based on the fact that the specific heat of steam rises with in-- crease fo pressure and temperature to a maximum value and then falls off again. It is thus possible to reheat to the desired extent the whole of the partially expanded steam with a smaller quantity of high pressure steam.