GB763919A - Steam power plants - Google Patents

Abstract

763,919. Steam turbine plant. SULZER FRERES SOC. ANON. Jan. 25, 1955 [Feb. 10, 1954], No. 2249/55. Class 110 (3). [Also in Group XIII] A steam power plant comprises a forced-flow, once-through steam generator which may operate at supercritical pressure and which has a furnace 3 lined with steam-generating tubes 8 and locating in its top portion a radiant superheater 11, 12, combustion gases passing laterally from the furnace through a short pass in which is disposed a reheater 16 and then downwardly through a pass locating a primary superheater 10 and feedwater preheater 6, the latter including a heat exchanger section 27, 28 wherein the incoming feed is further heated by steam tapped off from one of the turbines supplied by the generator. The heated feed is converted into steam in the tubes 8 and passes through a conduit 9, the primary superheater 10 and the radiant superheater 11, 12 to the highpressure turbine 14. Steam from this turbine returns to the generator through a pipe 15 and passes through the reheater 16 and then through a heat exchanger constituted by tubes 21 disposed coaxially within some of the radiant superheater tubes, so that the steam is further reheated in indirect contact with the superheated steam. The reheated steam flows to the low-pressure turbine 18 through a pipe 17. The tubes 21 are protected against overheating when the generator is being started up by the superheated steam flow. Fig. 2 shows a reheater disposed wholly within the convection pass from the furnace 3 and means whereby the temperature of reheat is regulated. The superheated steam from the primary superheater 31 flows through a heat exchanger consisting of a tube 33 disposed within a tube 38 through which passes steam from a reheater 37, the reheated steam flowing from tube 38 through a further reheater section 39 before returning to the lowpressure turbine through pipe 17. Superheated steam from tube 33 passes through a final superheater 36 and a pipe 13 to the high-pressure turbine. The reheat temperature is controlled indirectly by varying the temperature of the superheated steam entering the heat exchanger 33, 38 by means of a water spray attemperator 40 in the inlet pipe. The superheat temperature is subsequently adjusted to the required level by attemperation by means of a spray 41 in the heat exchanger outlet pipe 35 or by raising its temperature by opening a valve 43 to allow some of the steam to by-pass the heat exchanger. Specification 731,338, [Group XIII], is referred to.