GB549151A - Improved methods of and apparatus for burning finely divided solid fuel in suspension - Google Patents

Abstract

549,151. Pulverulent fuel furnaces : water-tube boilers. BABCOCK & WILCOX, Ltd. May 5, 1941, No. 5847. Convention date, July 31, 1940. Class 51 (i)] [Also in Group XIII] Pulverulent solid fuel is supplied in suspension to a combustion chamber or zone with a limited supply of air so that the slag produced possesses a relatively low fluid temperature and is removed from the combustion chamber or zone in a fluid condition while the :gases of combustion carrying further slag particles are passed into a second zone and supplied with additional air to effect combustion of the gases and solidification of slag. Where the fuel has a substantial iron content ferrous oxide is formed in the slag in the first combustion zone and is converted to ferric oxide in the second combustion zone. The process of combustion may be carried out in boiler furnaces of the 'kind described in Specifications 497,718 and 534,279, [Group XIII], and Fig. 1 shows one such form of boiler having a furnace chamber 10 lined with water tubes to which fuel is supplied by burners 27 with a limited supply of air from a conduit 25. Molten slag collects on the hearth 29 and is tapped off from a central opening (not shown) in the hearth. The gases flow from the lower part of the combustion chamber beneath a fluid cooled partition 20 to an upflow passage 12 near the roof 33 of which they are supplied with additional air through ducts 81 before passing through a passage above a fluid cooled partition 21 to the downflow passage .13 leading to the bottom of a convection section 11 of the iboiler separated from the passage 13 by a fluid cooled wall 22. The upflow and downflow passages 12, 13 are lined at the sides with steam reheater tubes 57 connected to upper and lower headers 56, 58 while the downflow flow passage 13 is subdivided by rows of superheater tubes 48 connected to superheater tube banks in the convection section of the boiler. Ashes separated from the gases tin 'the downflow :pass and convection section are discharged into a hopper 61. The convection section is divided into two compartments by a vertical -partition containing superheater and reheater tubes respectively the flow of gases through the compartments being controlled by dampers. Above 'these compartments ,air heaters are arranged for the combustion air.