GB932398A - Improvements in or relating to vapour turbine plant - Google Patents

Abstract

932,398. Turbine power-plant. BABCOCK & WILCOX Ltd. (Soc. Francaise des Constructions Babcock & Wilcox.). March 25, 1960, No. 10757/60. Class 122 (3). In a condensing steam-turbine plant in which the combustion air for the steam generator (not shown) is heated in a flue-gas air heater 20 and the condensate returned from the turbine condenser 4 to the generator is heated by steam bled from the turbine, the air is preheated before entering the air heater 20 in an air preheater 22 by heated condensate supplied at a variable rate. The turbine comprises high and low pressure stages 1 and 2 respectively with an intermediate reheater 3 and the condensate is pumped by a pump 5 through feed water heaters 7, 8 and 9 where it is heated by steam bled from the turbine through lines 10, 11 and 12 respectively. Combustion air for the steam generator is preheated in the preheater 22 by condensate circulated through a conduit 26 from a point 23 between the heaters 7 and 8 to a point 24 between the pump 5 and the condenser 4. The air is then further heated by combustion gases in the air heater 20. Some of the condensate flowing in the conduit 26 is pumped by a pump 29 through an economizer 30 and returned to the generator through a further economizer 21, the economizer 21 being heated by combustion gases before they enter the air heater 20 and the economizer 30 by gases by-passing the heater. In operation, the amount of condensate withdrawn at 23 is such as to ensure that the temperature of air entering the air heater 20 is sufficient not to cool the combustion gases therein below their dew point. In a modification, Fig. 2 (not shown), the condensate flowing between the heaters 8 and 9 and also that flowing through the economizer 30 passes through a de-aerator.