GB1007609A - Improvements in or relating to forced flow vapour generating systems - Google Patents

Abstract

1,007,609. Critical pressure boilers. SULZAR FRERES S.A. July 27, 1962 [July 27, 1961], No. 29029/62. Heading F4A. In a forced flow vapour generator operating at supercritical pressure working medium is recirculated at part load so that at all loads the transition zone of liquid to vapour is located in the heating surfaces of the combustion chamber. A feed pump 19 supplies working medium through an economizer section 20 and pendent tubes 24, 25 to headers 26, 27 from which the medium flows to a mixing vessel 30 before flowing to centrewall tubes 34 which are disposed as a partition in the combustion chamber 11 and which extend in vertical parallel relation between headers 32, 35. From the header 35 the medium flows to and through wall lining tubes 40 which also extend vertically and in parallel between inlet headers 37, 39 and an outlet header 41 which leads to a distribution header 42. From this point some of the working medium flows through superheating sections 52, 57, 59 in series to an H.P. turbine stage 61, and then via a reheater 62 to L.P. stage 64. The remaining portion of the medium is recirculated from distribution header 42 by a pump 45 and mixes with the fresh feed in the mixing vessel 30 before passing through the centre wall and water wall tubes 34, 40 in series. The amount of working medium recirculated is controlled in dependence on the load on the generator so that the transition zone at all loads is kept within the heating surfaces in the combustion chamber 11.