GB858813A - An improved furnace for fluidised bed combustion of solid fuels - Google Patents

Abstract

858,813. Pulverulent fuel furnaces. DING LERWERKE A.G. June 10, 1958 [June 11, 1957; Nov. 21, 1957; April 3, 1958], No. 18565/58. Class 51 (1). In a furnace having a fluidized bed 2 of solid fuel, secondary air is blown upwards through a slit 4 forming a Venturi nozzle between the primary and secondary combustion chambers 3 and 5. The air supply nozzles 6 project into the combustion chamber 3, and have tubes 9 for coolant associated with them. The single row of nozzles 6 may be replaced by a double row of nozzles, the cones of air from the nozzles intersect at the narrowest part of the slit. The cooling tubes of one row of nozzles may cross the combustion chamber while the cooling tubes of the other row of nozzles are bent back to return through the same wall. Further nozzles may deliver air at a plane midway up the combustion chamber, or nozzles projecting through the fuel bed may terminate at several different planes, all the nozzles forming a checkered pattern in plan. In a further modification, Fig. 7, nozzles 17 projecting into the combustion chamber deliver air tangentially to an imaginary circle within the chamber. The pipes leading to the air supply nozzles may be double walled to provide cooling tubes, or one or more cooling tubes may be welded to the air pipes, or the air supply pipes may be formed by a ring of cooling tubes welded together. The air supply tubes 29, Fig. 12, may be enclosed in heat-resistant ceramic jackets 28, a length of tube projecting in order to preheat the air. The tubes may be adjustable in height, and carry nozzles 32 of any desired shape. The tubes may be rotatable together with the nozzles to improve the distribution of air. Air may be supplied through holes 33 in the sides of the tubes. The pipes supplying air tangentially may be mounted on a ball-and-socket joint outside the furnace so that they may be tilted, or moved to project air tangentially to different imaginary circles, Figs. 13 and 14 (not shown). In another embodiment, Figs. 15-18 (not shown), a sleeve projects from secondary combustion chamber into the primary combustion chamber, and the combustion air is at least partly delivered tangentially.