Patent GB-308345-A (GB)
Title: Improvements in underfeed stokers for furnaces
IPC: F23K3/12
Filed: 1929-02-11
Abstract: 308,345. American Engineering Co., (Assignees of Preston H. E.). March 22, 1928, [Convention date]. Firebars and grates; fuel supports; ashpits; air supply, regulating.-In a mechanical stoker of the underfeed type the inclined fuel troughs and air chambers supporting the tuyere blocks are formed by a number of integral longitudinal steel beams 14, Figs. 1, 2 and 4, connected at their front ends to brackets 19 mounted on vertical supports 21 and at their rear ends to downwardly-extending plates 38 carrying castings 42 adapted to rest on roller bearings 15 to permit longitudinal expansion of the beams. The upper parts of the beams carry sectional plates 103 for supporting the tuyeres 102 to which air is supplied from the chamber 139, the passage of air to the tuyere chambers between the beams 14 being controlled by groups of valves 109, 111, 112 located at the base of the compartments into which the tuyere chambers are divided by transverse partitions, as described in Specification 308,293. The bottoms of the fuel troughs are formed by a number of secondary pushers 126, as described in Specification 314,624, which deliver the fuel downwardly over reciprocating grate sections 9 at the lower ends of the troughs into an ash-pocket 5 at the base of which is provided crushing apparatus 6. The grate sections 9 comprise, as shown in Fig. 30, side plates between which extend the tie-bars 576, by which the grate sections are reciprocated, and grate-bar supports 435, 436, 437. The upper grate-bars 439 comprise overlapping plates having tapering air spaces which deliver the air upwardly into the fuel. They are provided with lugs at the upper and lower ends to engage with the upper and intermediate bearers. The lewer bars are of somewhat similar construction, but have a curved contour. They are secured to the intermediate bearer by pins 573 and have lugs engaging with the rear end of the lower bearer. The grate sections are supported by and reciprocated on members attached to the beams 14. As shown in Figs. 15 and 17, the front wall of the ashpit 5 into which pass the ashes from the grate sections 9 forms part of an air conduit into which air is delivered through the passages 138 and from which it passes upwardly into the space beneath the grate sections 9. The wall comprises upper and lower bar sections 202, 199 and intermediate sections 201 supported by lugs upon projections on vertical partitions 247, 248 constituting air passages. The walls of the bars are provided with internal ribs and also external ribs on their outer vertical sides forming passages through which air is directed upwardly into the ashes for the purpose of consuming residue fuel. As shown in Fig. 17, certain of the partition walls are curved for the purpose of distributing the air entering through the passage 138 uniformly over the ashpit wall surface. A guard-plate 324 which is interlocked with a supporting plate 323 is arranged above the ashpit wall and by its removal any of the wall sections of the ashpit may be readily removed or renewed. Gates 288 are provided at the lower portion of the conduits within the ashpit wall to allow for the removal of ash which may enter the conduits.