Document aBkpgzpp9mJ1z8aaNY1wzVL5y

Unit of Fig. 3 has a traveling grate Fig. 10, uses a worm. AU have positive loosely on shafts concentric to the j." coal and refuse are distributed over movable wedge blocks in the tip. A powered by motor, with variable-speed that movea forward alowly toward the uniform feed as their objective. main impeller shaft Blades are the grate by an overthrow rotor. A low-pressure fan supplies air for com transmission, and by hydraulic drives, front, or coal-feeding end, of the fur- Rotors. In mechanical spreader units, signed to give a hammer-mill effecC$d-' icries of stepped shoes set on a sharp bustion. Separate motors drive feed with a constant-speed variable-dis noce. It discharges ash continuously. coal feeds down from the hopper to breaking up any wet coal that teodi;^. slope, and moved by rocker action, screw, conveying-air fan and combus placement pump supplying fluid to' a Such deaigna prove well suited to large paddle or wheel-shaped distributing to lump, fn another design, the rotor feeds the coal. tion-air fan. Variable-speed transmis constant-stroke variable - speed hy installations, and have been applied to rotors. These move at high speed to is divided into sections, each hiring^"' Fnumoik Ipraoder. A different meth sion adjusts rate of fuel feed and an draulic motor. boilers with steaming capacities of throw the coal out into the furnace. four blades at o slight angle to od of spreader firing is shown in Fig. air-volume regulator maintains de The stoker of Fig. 2 has an inte 250,000 lb per hr. Some engineers be There are two methods in common use, shaft. Angles are such that one bladsjv' 8 and 10. These units employ a jet of sired air supply. grated hydraulic drive that serves all lieve much larger unita can be built. both of which claim advantages--over throws coal to the right, while the neit'*^ steam or air to project the coal into the Another PnevmetU. In the design of parts, and provides automatic fuel-air teol Feeders. Spreader stokeri can throw and underthrow. They are so throws to the left. This crlsscr*ini,v,v furnace. The unit of Fig. 8. which fea Fig. 10, feed screws spaced across the ratio control. A single pump, driven by handle a wide range of coal types, in named from the point on rotor travel feed is designed to give uniform futi.Vl tures a remotely located feeding mech width of the stoker move coal from the a constant-speed motor (or turbine) cluding lignite. Aa to aise, they do beat where Incoming coal meets blades. distribution. '^ir- anism and hopper, can readily be ar- hopper to the point of injection. An supplies oil to a hydraulic motor driv on cools under about 1V4 in., with pre Overthrew. Fig. 1-4, and 7, show Wor<ooiine is provided on msoy^*^ *nged to feed directly from a bln or agitator wheel in the hopper prevents ing the rotors, and hydraulic engines ferred aise of the order of 44x0-in.,nut various designs employing the over feeding ' and distributing eesemblk*-' ,,*+. J bunker. Coal in the hopper moves coal piling up on the screw. An air jet - actuating moving grate*, ash-discharge and alack. Coarse coat tends to wear throw principle. Rotors, spaced to give The detail of Fig. 8 shows one rTBOge>&: lowly down to a feed worm, which has set just below the end of the screw grates and feed rams. Fuel-air ratio the feeders and may form clinker. desired coverage, are usually designed ment, with a reservoir ct the top * siting section to break up lumps too catches up the coal os it falls and control acts on proportioning valves Cool is usually withdrawn from a so individual paddles or elements can tending across the unit and cooled sec-^>4 isige for transport by pneumatic spreads it over the grate. At the seme in the discharge from the pump, regu if hopper by a mechanical feeding device whose role is to insure an even, un interrupted supply to the distributing .be readily removed and replaced. Feed er assembly provides means to correct for change in coal alee to maintain tions in each end frame. In designs, the feeding machine end grate section covered by U worfc to- ucans. The worm carries the cool in a *s state to the transfer housing. Fig. Here a stream of oir from a high- time, this air jet provides an overfire air stream. Spreader Drive*. Many feeder mech lating Row to the various drives and relief to the oil tank. The spreader stoker has come into system. A variety of means is em desired distribution pattern. For exam gether with an Individually contnw*o.V\j f^ssure radial-vane fan picks it up anisms ore motor driven, with some wide use in recent years because it is ployed : a chain feeder does the Job in ple. the unit of Fig. 3 has a spill plate. air supply. The number of sections conveys It through a pipe to the form of variobie-speed transmission relatively simple, low in first cost, and - Fig. I; a set of feeder rams. Fig. 2; o When moved forward, it causes the pends on furnace width. burner noiste. Hot gat from the fur- to control rate of fuel feed. Usually insensitive to coal characteristics. With double-acting ratchet mechanism and rotor to throw more of the fuel toward An indication of the versatility n#*t may be used as the transporting e steam-turbine drive, and some proper controls and provisions for rotary feeder in Fig. 6; a hydraulic the rear of the furnace, and when the spreader method of firing * v , if so desired. times a hydraulic drive, can be ap-' holding cinder carryover to an accept reciprocating.drive working sectional moved backward does the opposite. seen in Fig. 7. Here firing of waste > The spreader nozzle is wedge shaped; plied. Dumping grates may be hand able level it gives highly satisfactory pushers in Fig. 4; a series of recipro Vmtofihraw, Fig. S shows an under is provided for by the addition - rnt and back distribution is regu- operated or powered by steam, air or service under a.wide variety of condi cating plates working off the main throw rotor, which consists of small hinged chute, down which the `tied by elevating or depressing 'the hydraulic cylinders. Moving grates tions. It has a reputation for quick iineshaft, Fig. S. Still another example, blades of special curvature, suspended flowa, under control of a gate. * n**le tip, and side distribution by used for continuous ash discharge ore response to load changes which Is, 100 (764) SOWER Daci^b*' 'own * December 1*48 (7*5) tOt