GB721155A - Improvements in or relating to steam generating and superheating apparatus - Google Patents

Abstract

721,155. Steam &c. boilers ; superheating. BABCOCK & WILCOX, Ltd. June 5, 1951 [June 9, 1950], No. 13301/51. Class 123 (3). A steam boiler comprises a vertical furnace chamber 10 which is lined with steam-generating wall tubes 12, 14, 17 and is fired by rows of pulverised fuel, &c. burners 36, 38, the combustion gases flowing from the furnace successively through a tube screen 14a formed by extensions of the rear wall tubes 14, a convection heated superheater 24, 26, and further steam-generating tubes 20, 22 to an air heater 60, and the super-heat temperature is regulated by withdrawing relatively cool gases from the inlet duct to the said air heater and directing them by a fan 66 through ducts 63, 68, 69, 70 into the lower end of the furnace in such manner that they continue to flow in a stream between the main combustion zone and the rear wall tubes 14. A control and shut-off damper 90 is fitted within the duct 68 and is actuated bv manually-operated means 98 or, alternatively, automatically in accordance with the steam temperature ; the duct 68 is also fitted with an atmospheric connection 84 provided with a pressure-responsive valve 86 adapted to admit air to the duct when a tendency to reverse flow therein arises. In the construction shown the duct 70 discharges between the spaced lower ends 74, 76 of the tubes 14 throughout the whole width of the rear wall of the throat 54 of the boiler ash pit 57, but in a modification the duct 70 discharges through an intermediate portion of the front inclined wall 52 of the hopper 50 above said pit. Specifications 367,699, 504,114, 516,070, 523,870 and 540,119 are referred to.