GB861231A - Improvements in or relating to shell-type boilers - Google Patents

Abstract

861,231. Return-tube steam boilers. JOHN THOMPSON (WILSON BOILERS) Ltd. Jan. 30, 1959 [Jan. 13, 1958; June 14, 1958], Nos. 1119/58 and 19119/58. Class 123(2) A shell-type boiler 12 comprises a horizontal furnace tube 10 which is welded at its rear end to a tube plate 17 constituting the front plate of a wet-back combustion chamber 14 having no refractory linings and a dished end 18, the front end of the tube 10 being supported by welding in a front tube plate 15 between which and the tube plate 17 is arranged a nest of return tubes 19 situated below the tube 10. Combustion gases from a burner 29 in a smokebox 25 mounted on a front plate 13 and communicating with the front end of the chamber 10, pass successively through the latter, the chamber 14 and the nest of tubes 19 and return through the boiler again to an uptake 24 secured to a rear tube plate 16 through two further nests of tubes 39 which are located one on each side of the furnace tube 10 and extend between the front and rear tube plates 15, 16. Solid or tubular stays 21 and an access door 22, which need not be mounted centrally as shown, are provided between the rear tube plate 16 and the dished end 18 of the chamber 14 which may carry in its crown a fusible plug and may have a corrugated wrapper plate to withstand greater boiler pressures. An axial flow impeller 26, mounted at the front of the boiler, supplies combustion air to the burner 29 through an annular duct surrounding the burner, the combustion air being preheated by the combustion gases flowing from the tubes 39 in a front gas return chamber between the front plate 13 and the tube plate 15.