GB835308A - High pressure steam power plants - Google Patents

Abstract

835,308. Steam superheaters. SULZER FRERES S.A. June 11, 1957 [July 11, 1956], No. 18417/57. Class 123(3) In a steam generator operating at high, for example supercritical, pressure, overheating of radiantly-heated reheater tube platens disposed in the generator furnace is prevented by enclosing the more intensely heated marginal areas of the platens by tubes through which flows high pressure steam or water. As shown in Fig. 1, in the generator 1 which is heated by burners 17, the working fluid enters at 2 and passes through a feedwater preheater 3 and vaporizing section 4 to a convection superheater 6. From here the steam flows to a second superheating section 7 forming a wall lining for the upper part of the combustion chamber and thence through tubes 8 enclosing the marginal areas of a reheater platen 12. The steam then flows through a final superheater 9 to a high pressure turbine 10..From the high pressure turbine the expanded steam flows through the reheater platen 12 and a second reheater section 13 to the low pressure turbine 14. In modifications the marginal protective tubes for the reheater platen forms part of the vaporization section or of the feedwater preheater. Thus the stream of heating gases from the furnace cannot impinge directly on the reheater tubes which, particularly when operating at low load or when starting up, do not carry steam at sufficient pressure to ensure adequate cooling. As shown in Fig. 5, the marginal tubes 8 may be bent to form several passes under the reheater tubes 12. Where it is only necessary to protect the bottom and one side of the reheater the arrangement shown in Fig. 6 is adopted.