US2538944A

US2538944A - Mechanical stoker

Info

Publication number: US2538944A
Application number: US620243A
Authority: US
Inventors: Earle C Miller
Original assignee: Riley Power Inc
Current assignee: Riley Power Inc
Priority date: 1945-10-04
Filing date: 1945-10-04
Publication date: 1951-01-23
Anticipated expiration: 1968-01-23

Description

Jan. 23 1951 E. c. MILLER 2,538,944

MECHANICAL STOKER Filed Oct. 4, 1945 2 Sheets-Sheet l J 233 191 E. c. MILLER 205389944 MECHANICAL STOKER Filed Oct. 4, 1945 2 Sheets-Sheet 2 Patented Jan. 23, 1951 UNITED? STATES PATENT OFFICE MECHANICAL STOKER Earle? C; Miller. Worcester 'Mass, assighor to Riley Stoker Gdrporationg. Worcester, Mass:,-. a corporation .of Massachusetts Application October-4, 1945, Serial No; 620.243

7. Claims;- (Cl. 1598 128) This invention relates to' mechanical stoliers. and more particularly to stokers ofthesc -called" spreader type having" revolving blades to throw fuel particles into a furnace for combustiontherein.

Spreader stokers usually comprise a horizontal rotor mounted in front of an opening in a furriace wall and carrying a series of blades'to which the fuel is supplied by a' suitable feedingmechanism. The furnace is provided with a grate which supports a bed of burning fuel, and the blades throw fue1 through the wall opening so that the very fineparticles may burn in suspension while the coarser particles are deposited on the fuel bed. Since the' widthof the grate usually considerably exceed the length of the rotor", the rotor must spread the fuel laterall'yin order to" obtain uniform fuel distribution over the grate. This problem is complicated by the fact that grates of many different widths are encountered in various installations; Priorstoke'rshave been lacking in the ability to'spread the fuel in a uniform manner; and'particularly lackingin adapta bility' for use with varying grate widths; The

rotors are necessarilyexposed toconsiderable heat radiating outwardly through the" wall" opening;

and this has? caused warpingof shafts and other It is accordingly one object of the invention to provide an improved construction for therotoif of a spreader. stoker whereby a moreuniform dis-- tribution of thefuel may be obtained.

It is a further objectofthe invention to provide a spreader stoker rotor having simple and de pendable means whereby the distribution of the. fuel may be altered to adapt the stoker to grates of varying'widths.

It is a further object of the invention to provide a spreader stoker inwhich the rotoris more 2 Fig. 2 is" a sectiontaken on theline 2- 2 or:

1 Fig. 3'- is a view similar to Fig. 2, but'showihgi therotor turned 90-degrees ina forward dirc-.

tibn';

Fig. 4" is an enlarged section taken on the 4' !of Fig. 2';

Fig. 5 is a detail view of ahub' member; Fig. 6" is a perspective view of" a hub member:- I and Fig; "7 is' a perspective View of a fuel impeller 01' paddle.

The embodiment illustrated comprises an" up= right furnace wall Hi having a laterally elong'a 'd' rectangular opening H therein; This open rig flares both vertically and horizontallytoward the rear or furnaceside of the wall. The usualmetal front plate 1'2" is provided on the" front or outer side of'the-wall', this plate having an opening M which registers with the wall opening II. The furnace will be provided with asuitable grate (hot shown) below the opening ll, and inac cordance with the customary practice this-grate will be appreciably widerthan the opening. in thecase of wide furnaces, a plurality of wanopenings 'will be provided;

Referringgnow to-Figs. I and 2;. it willbe seen that a semi cylindric'al" trough or'rotor casing" f6 is" mounted on the front plate t2 immediately below the opening W, this'troughbeirig clbsedat its ends by upright Walls ll. Withinthetrough' there is provided" a rotorcomprising, a horizontal shaft I8" which" extends along" the axis of" the trough andparallelwith the front plate 2, this line 35; shaft being rotatably' supported in bearings?!) of any suitable type carried" by the end walls f1 of the trough. The shaft I3" is rotated by any suitable means in an over rurining direction such that its upper" surface travels toward the 7 furnace, and on this shaft there are mounted. impellers or paddles 2! arranged" to throw" fuel rearwardly through the wall opening H. The front wallof the trough it extends upwardly'ahd isprovided at its upper edge with a forwardly pl'ate- 24; This plate-extends rearwardly'over' the trough; there'ar' edge"- or the plate beihg located above the rotor; A ram' 25'" is slidably supported on the plate 2 and arranged to be" reciprocated 50? forwardly and'rearwardly bysuitable rockerarms 2 -3-1 fuel hopper- '28 isinriounted' above therani- 253 Thishopper sup f-uel tathe rain; and the latter pushesfuel at a clesi red rate rearward-1y over the; plate 2 the fuel moppingfro-mthe 65? rear edge of-thisplat'e into'the path of the irh pellers 2|. The trough I6 is preferably constructed with a removable section 39 in its lower front portion to permit ready access to the rotor.

The rotor is constructed in a novel manner to provide great practical advantages. Thus the rotor shaft I8 is formed with a plain cylindrical outer surface, this shape being the simplest and least expensive to manufacture and the least likely to be distorted by heat. Along the shaft there are mounted a series of hubs each of which comprises a pair of oppositely disposed hub members 32. Each of these members 32 has a flat or plane outer surface 33 and an inner surface formed with a semi-cylindrical groove 34 for engagement with the shaft, the surface 33 being parallel with the groove axis. At one side of this groove there is provided a plain hole 36, and at the other side there is provided a threaded hole 31. An additional threaded hole 38 is provided through the fiat surface 33 and intersecting the groove 34, this hole being offset laterally from the axis of the groove in a direction toward the plain hole 36. The two members 32 of each hub are clamped against the shaft LG by means of two screws 48 which extend through the plain holes 36 and into the threaded holes 37, the arrangement being such that when a member 32 is on the top of the shaft the corresponding plain hole 36 will be in front of the shaft. As shown in Figs. 2 and 3, the hubs are spaced rather closely together along the shaft, and adjacent hubs are turned 90 degrees with respect to one another. In the embodiment illustrated nine hubs are provided, but this number ma be varied depending upon the width of the wall opening I I.

These hubs support pairs of opposed impellers 2|. As best shown in Figs. 4 and '7, each impeller comprises a fiat blade 32 and a base 43 integral with the blade, these portions being at approximately right angles to provide a structure L- shaped in cross section. The base is provided with a plain hole 45 for the reception of a single screw 46 which extends into the threaded hole 38 and thus fastens the base against the flat surface 33 of the hub member 32, the blade 42 being in advance of the base 43 in the direction of rotation. The width of the blades 12, measured parallel with the axis of rotation, considerably exceeds the width of the hubs 32, so that the blades on adjacent hubs may overlap appreciably.

It will now be apparent that the impellers 2| can be pivotally adjusted about the screws 46 to vary the angular positions of the blades 42 relative to the axis of rotation. This has very great practical advantages, as it makes it possible to adapt the stoker to furnaces of various dimensions and obtain proper distribution of the fuel. By increasing the angularity of a blade with respect to the axis, the blade can be made to throw the fuel more to one side, and the lateral spread of the fuel can be controlled in a desired manner. In general I have discovered that th blades at the right hand side of the rotor center should be set to deflect fuel to the right, and the blades at the left hand side of the rotor center should be adjusted to deflect fuel to the left. Furthermore, the blades near the center of the rotor should have the greatest angle, the angularity of succesive blades preferably decreasing gradually toward the ends, the end blades having little or no angularity. Thus, with nine pairs of blades as shown in Figs. 2 and 3, the pair at the center may be set at say 30 degrees, with one turned to the right and the other to the left. The blades next adjacent may be set at say 20 degrees, the next adjacent blades at say 10 degrees, and the remaining blades (two pairs at each end of the rotor) at zero degrees, i. e. parallel with the axis of rotation. These angles may be increased if the furnace is wide enough to require a greater lateral spread of the fuel. The construction makes it possible to obtain a very uniform fuel distribution while avoiding appreciable impact of fuel particles against the sides of the wall opening H.

Rierring now particularly to Figs. 1 and 4, it will be noted that the fuel-engaging faces of the impeller blades 42 are not radial but are offset in the direction of rotation. Thus when a blade is in its uppermost or fuel-striking position, its advancing face will be located somewhat rearwardly of the shaft axis. By reason of this construction the rotor shaft can be mounted somewhat farther from the furnace, where it will be better protected from the heat, while the impeller blades nevertheless distribute the fuel particles in a desire-:1 manner. Since the hub members 32 cover nearly the entire outer surface of the rotor shaft within the casing 16, they are of considerable value in shielding the shaft from the furnace heat.

In the operation of the invention, the reciprocating ram 25 will push fuel from the hopper 23 rearwardly over the plate 24. The fuel will fall from the rear edge of this plate into the path of the revolving blades 52, which will throw the fuel particles rearwardly through the opening H into the furnace. The fine particles will burn in suspension, while the coarse particles will fall upon the furnace grate to form a bed of burning fuel. Because of the novel angular positioning of the blades, varying from a maximum angularity at the center of the rotor to zero angularity at the ends of the rotor, the fuel will be distributed with great uniformity throughout the furnace. The same rotor can be used wi h furnaces of different widths by varying the adjustment of the blades. The blades can be adjusted without disturbing the rotor shaft and in fact while the furnace is still in operation, since the removal of the trough section will permit ready access to the rotor. To adjust each blade the operator needs to loosen only a single screw as, and a very few minutes will be sufficient, with only a brief interruption in the fuel feed. The blades are mounted in diametrically opposed pairs, with adjacent pairs displaced degrees about the rotor axis and overlapping in the axial direction. Thus there are four rows of blades, with the blades in adjacent rows staggered. This construction provides for dynamic balance, it avoids any gaps along the rotor, and it pirinits angular adjustment of each blade independently of adjacent blades, all in a simple, rugged and inexpensive structure.

Having thus described my invention, what I claim as new and desire to secure by Letters Patcnt is:

1. A fuel distributing rotor for a mechanical stoker comprising a supporting structure rotatable about a horizontal axis and having outwardly facing .ne surfaces parallel with axis, a series of fuel-tlnowing impellers carried by said structure and each including a base and a blade joined at approximately right angles to provide a device L-shaped in cross-section with the blade in advai e of the in the direction of rotation, and means fastening the bases of the impellers to the said plane surfaces for pivotal adjustment about axes extending perpendicular to the said surfaces.

2. A fuel distributing rotor for a mechanical stoker comprising a supporting structure rotatable about a horizontal 'axis and having outwardly facing plane surfaces parallel with the axis, a series of fuel-throwing impellers carried by said structure and each including a base and a blade joined at approximately right angles to provide a device L-shaped in cross-section with the blade in advance of the base in the direction of rotation, and a single screw fastening the base of each impeller to the corresponding plane surface for pivotal adjustment about the axis of the screw.

3. A fuel distributing rotor for a mechanical stoker comprising a horizontal rotatable shaft, a series of hubs on the shaft and each shaped to provide two diametrically opposite outwardly facing plane surfaces parallel with the axis of the shaft, a pair of diametrically opposed fuelthrowing impellers carried by each hub, each impeller including a base and a blade joined at approximately right angles to provide a structure L-shaped in cross-section with the blade in advance of the base in the direction of rotation, and means fastening the bases of the impellers to the said plane surfaces for pivotal adjustment about axes extending perpendicular to the said surfaces.

4. A fuel distributing rotor for a mechanical stoker comprising a horizontal rotatable shaft, a series of hubs on the shaft and each shaped to provide two diametrically opposite outwardly facing plane surfaces parallel with the axis of the shaft, a pair of diametrically opposed fuelthrowing impellers carried by each hub, each impeller including a base and a blade joined at approximately right angles to provide a structure L-shaped in cross-section with the blade in advance of the base in the direction of rotation, adjacent hubs being turned 90 degrees with respect to one another so that the blades are arranged in four rows with the blades in adjacent rows staggered, the blades in each row being of sufficient width to overlap the blades in the adjacent rows, and means fastening the bases of the impellers to the said plane surfaces for pivotal adjustment about axes extending perpendicular to the said surfaces.

5. A fuel distributing rotor for a mechanical stoker comprising a horizontal rotatable shaft having a cylindrical outer surface, a series of hubs on the shaft and each including a pair of oppositely disposed members clamped against the shaft by fastening means and providing two diametrically opposite outwardly facing plane surfaces parallel with the axis of the shaft, a pair of diametrically opposed fuel-throwing impellers carried by each hub, each impeller including a base and a blade joined at approximately right angles to provide a structure L- shaped in cross-section with the blade in adranged in four rows with the blades in adjacent rows staggered, the blades in each row being of sufiicient width to overlap the blades in the adjacent rows, and means fastening the bases of the impellers to the said plane surfaces for pivotal adjustment about axes extending perpendicular to the said surfaces.

6. A fuel distributing rotor for a mechanical stoker comprising a supporting structure rotatable about a horizontal axis, and a longitudinal row of fuel-throwing impellers projecting from the supporting structure and providing fuel-striking surfaces positioned at varying angles with respect to the axis, the impellers at the right side of the rotor center being set to deflect fuel toward the right, and the impellers at the left side of the rotor center being set to deflect fuel toward the left, the angularity of the impellersdecreasing progressively from a maximum adjacent the center of the rotor to a minimum adjacent the ends of the rotor.

'7. A fuel distributing rotor for a mechanical stoker comprising a supporting structure rotatable about a horizontal axis, and longitudinal rows of fuel-throwing impellers projecting from the supporting structure and providing fuel- :triking surfaces positioned at varying angles with respect to the axis, the impellers bein arranged in pairs of diametrically opposed impellers with laterally adjacent pairs turned degrees with respect to one another to form four rows of impellers with the impellers in adjacent rows staggered, the impellers at the right side of the rotor center being set to deflect fuel toward the right, and the impellers at the left side of the rotor center being set to deflect fuel toward the left, the angularity of the impellers decreasing progressively from a maximum adjacent the center of the rotor to a minimum adjacent the ends of the rotor.

EARLE C. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS