GB856632A - Improvements in power plants - Google Patents

Abstract

856,632. Nuclear power plant. BABCOCK & WILCOX Ltd. March 7, 1957 [March 8, 1956], No. 7559/57. Class 39(4). [Also in Groups XIII and XXVI] A power plant comprises a nuclear reactor cooled by the circulation of a fluid medium which also heats a vapour generator connected through a vapour heating means to a turbine, the vapour heating means being supplied with combustion gases at a pressure of several atmospheres and the same gases being used to drive a gas turbine which itself drives the means for circulating the fluid medium. Carbon dioxide is circulated by blowers 101 driven by a gas turbine 71 as a coolant through a nuclear reactor 100 and as a heating fluid through a vapour generator including four heat exchangers or boilers 25, 26, 27, 28 and a heat exchanger or economiser 30. The heat exchangers 25, 26, 27, 28, 30 are arranged in series in the heating fluid path and the boilers 25, 26, 27, 28 generate steam at successively lower pressures. The heating fluid entering the boiler 26 is joined by hot fluid from the reactor through a duct 22 which is at a lower temperature than the fluid in the duct 21. Some of the fluid leaving the boiler 28 flows through the economiser 30 back to the reactor, the remainder is returned direct to the reactor through the duct 23. A feed pump 31 supplies the economiser 30 with water. A pump 37 supplies water to the steam drum 38 of the lowest pressure boiler 28. The excess feed water is returned to an expansion drum 35. Part of the water from the steam drum 38 is taken by a pump 39 and fed into the steam drum 40 of the lower medium pressure boiler. 27. The steam drums 42, 44 are similarly fed by the pumps 41, 43 respectively from the steam drums 40, 42. The saturated steam from the drums 44, 42, 40, 38 is heated in superheaters 540, 520, 500 and 480 and led respectively to the stages 61 to 64 of a steam turbine 60. The superheaters are heated in a combustion chamber 45 to which combustion air under pressure is supplied by a battery 46 of freepiston compressors. The steam leaving the high pressure turbine stage 61 is led to the inlet 56 of the superheater 520 before being supplied to the following stage 62. A low pressure stage 65 utilises saturated steam obtained from the expansion drum 35. The exhaust steam from the turbine 60 is condensed in a condenser 66 and passed by a pump 67 to a feed tank 68 which supplies the pump 31. Water from the expansion drum 35 is returned to the feed tank 68 through a cooler 69. The flue gases leaving the combustion chamber 45 are expanded in the turbine 71. In a modification, the superheater 480 and possibly the superheater 500 may be placed in the path of the exhaust gases of the turbine 71. The superheating of the steam may be in two stages, the primary superheat being assured by the heat of nuclear origin and the secondary superheat by the conventional fuel. The combustion air may be supplied by compressors of any type. A by-pass 73 controlled by a valve 74 may be provided to short-circuit the combustion chamber 45 to enable the turbine 71 to be run to drive the blowers 101 on starting or shutting down.