Patent GB-957024-A (GB)
Title: Steam power plant comprising a steam generator and a multi-stage prime mover
IPC: F01K7/22
Filed: 1960-08-25
Abstract: 957,024. Steam turbine plant. SULZER FRERES S.A. Aug. 25, 1960 [Sept. 3, 1959], No. 29459/60. Heading F1T. A steam power plant comprising a steam generator and a multistage prime mover having inter-stage reheating of the partially expanded working medium between at least two pairs of adjacent stages in which the inter-stage reheating between at least one pair of adjacent stages takes place in a flue-gas heated reheater and the inter-stage reheating between at least another pair of adjacent stages takes place in a steam heated reheater has the steam generator divided into two halves and the tube system divided into two parallel sections one in each half and each containing evaporating and heating surfaces for the supply of steam to the prime mover, the flue gas in reheater being arranged in one of the halves and the steam for the steam heated reheater being supplied by the other half; the firing system being arranged so that the relative heating of the two halves can be varied. The steam generator 1 is divided into two equal sections 2, 3 and each section can be heated separately. This can be effected either by separating the two sections from one another by a wall which may consist of boiler tubes and providing in each section at least one firing system operable independently of that in the other section or by dispensing with a partition wall and providing a firing system which can be regulated and which is adjustable in respect of the tube system e.g. by sub-dividing the firing system into a number of swinging burners. The tube sections 2, 3 are each provided with a feed regulating station 4, 5 and a steam pressure regulating station 10, 11. The common line steam pipe 12 leads through a regulator 13 to the first high pressure stage 14 of a multi-stage turbine. A pipe 16 leads the exhaust of this stage to a flue-gas-heated first inter-stage reheater 17 which is located in the section 3 of the steam generator. The outlet of the reheater 17 is connected by a pipe 18 and valve 19 to the second pressure stage 20 of the turbine. From the stage 20, a pipe 21 leads to a second interstage reheater 22 which is heated by high pressure steam from the section 2 of the steam generator. The outlet of the reheater 22 is connected to the low pressure stages 25, 27. The condensate from the condenser 29 is fed back to the steam generator through bled steam feed water heaters 32, 37. When the power plant is started up, only the section 2 is first put into operation, the feed water flowing through the regulating station 4 to the preheating part, the evaporator part and the first superheater part of the tube system; through the second intermediate reheater 22, the final superheater part, the by-pass line 42, 46 and the starting cooler 47 into the condenser 29 and back to the steam generator. When the superheating temperature has been reached in section 2, the first pressure stage 14 is heated up with part of the steam and at the same time section 3 of the steam generator is put into operation. The steam from stage 14 together with steam passing through the line 48 cools the flue-gas-heated first intermediate superheater 17 in the section 3. The steam from the intermediate superheater 17 then heats the other stages of the turbine or flows, if required, through the bypass lines 50, 46 to the starting cooler 47. When the section 3 has reached its superheating temperature, the turbine plant can be run up. In a modification, the steam between the second and third stages is reheated also by the exhaust steam of the first stage. By-pass valve across the reheater 22 and the exhaust steam reheater enable the reheat temperatures between the first and second stages and the second and third stages to be equalised with equal loading of the sections 2 and 3 of the steam generator.