GB809240A - Improvements in steam generating and superheating plant and an improved method of producing low pressure superheated steam - Google Patents

Abstract

809,240. Water-tube steam boilers; superheaters. BABCOCK & WILCOX Ltd. July 12, 1957 [July 13, 1956], No 22112/57. Classes 123(2) and 123(3) A plant for the superheating of steam from a low pressure source, for example, a nuclear reactor 10, and for the continuation of a supply of superheated steam to the point of use, for example, a steam turbine, when the steam supply from the reactor is discontinued, comprises a steam generating and superheating unit having an upright radiation chamber 88 receiving gases from a cyclone furnace 130 and locating in its upper part pendent superheater sections 116, 117. Behind these superheater sections the chamber has an outlet into a lateral pass 44 locating further pendent superheater sections 118, 78, 74. The cyclone 'furnace 130, its secondary furnace 136 and the lower part of the chamber 88 up to a level 140 are lined with steam generating tubes extending between a header 142 and a steam and water drum 20. In the normal operation of the plant, steam at, for example, 2,400 lbs./sq. in., flows from the drum 20 into a tubulous heat exchanger 16 wherein it comes into indirect heat exchange contact with L.P. steam, at 350 or 600 lbs./sq.in., from the reactor 10. The H.P. steam is condensed, condensate returning to the drum through a line 34, and the L.P. steam partially superheated, flows to a superheater inlet header 40 whence it passes successively through tubes lining the pass 44, the superheater sections 74, 78, tubes lining the walls of the chamber 88 above the level 140 and the superheater sections 116, 117, 118, finally passing from an outlet 122 to a turbine at a temperature of 1100‹F. If the supply of L.P. steam from the reactor 10 is discontinued, the supply of superheated steam to the turbine is maintained by diverting the flow of steam between the drum and the heat exchanger to the superheater inlet header 40, a valve 258 in a by-pass pipe 250 being opened and valves 252, 254 in the heat exchanger steam supply and condensate return lines 18, 34 respectively being closed. Under these circumstances, the pressure of steam leaving the drum is reduced to the normal pressure of steam from the reactor and the turbine continues to receive steam at the same pressure and temperature. Specifications 338,684 [Class 123(ii)] 526,825 and 598,141 are referred to.