US1764998A - Apparatus for feeding and metering pulverulent material - Google Patents

Description

June 17, 1930. E. e. BAILEY 1,764,998

I APPARATUS FOR FEEDING AND METERING PULVERULENT MATERIAL FiledApri} 24, 1924 2 SheetsShe.et l

June 17, 1930. B EY 1,764,998

APPARATUS FOR EEEDING AND METERING PULVERULEN'I MATERIAL Filed April 24, 1924 2 Sheets-Sheet 2 Patented June 17, 1930 UNITED STATES PATENT OFFICE ERVIN G. BAILEY, OF CLEVELAND HEIGHTS,

OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS,

T FULLER LEHIGH COMPANY, A CORPORATION OF DELAWARE I Application filed April 24-,

This invention relates to an apparatus for feeding pulverized material, especially adapted for feeding pulverized coal either directly to a furnace in which it is used for fuel, or to a producer by which it is contion for eflicient combustion.

In the use of pulverized coal as a fuel it has been found difficult to obtain uniformity of feed to the furnace, due in part to the condition of the material in the bin or receptacle from which it is taken, and in part to the mechanical nature of the devices employed for effecting the feed.

In accordance wlth the present invention the pulverized material coming from the bin. or receptacle is first acted upon by a preparing or conditioning appliance which mechanically breaks up any lumps or aggregation of particlespoming to it and introduces air in such a inanner that the particles remairrjseparatedand in fluify condition, the voids being filled with air, so that the material leaving this conditioning appliance and being delivered therefrom by gravitation accumulates inIa mass or column of substantially ,4 uniform density, with the solid particles 'li ghtly contacting With, and supported upon, one another, as distinguished from floating in suspension, but having the voids relatively large and freshly filled with air, so that the particles do not I adhere in groups or form lumps of a greater density than the desired or for the accumulated mass.

The material thus prepared or conditioned by being aerated and brought to the desired substantially uniform' density, is delivered by a feeding device, which may be, and as herein shown, also is, a measuring device, into a duct through which it is carried by a current of air to the desired final delivery point for the powdered material.

By reason of the aerated and uniform condition of the pulverized material coming to the feed wheel the individual particles are suspended and substantially uniformly disproper density 1924. Serial No. 708,821.

tributedin the air current, which should have sufficient velocity to prevent the settling of the particles in their passage through the duct to the point of final delivering. v

Fig. 1 is a general view in elevation of a complete apparatus for delivering pulveriz'ed coal with the particles suspended in the air current, said apparatus embodying the appliances for preparing and feeding the pulverized material forming the subject of this invention.

Fig. 2 is a vertical longitudinal section of the principal portion of the apparatus for preparing and feeding the pulverized material, and A Figs. 3, 4, 5 and 6, horizontal sectional views on lines X3, X4, X5, X-6, of Fig. 2, respectively.

-Referring to Fig. 1, the bin, or supply receptacle, in which the pulverized material to be delivered is contained, is shown at 2, being vertically over the preparing and feeding'appliances, shown collectively at 3 in said figure, by which the'pulverized material is fedinto the duct, or pipe, 4, leading to the gas producer, furnace,- or other desired delivery point, the current or blast of air by which the pulverized material is carried through the duct, 4, being supplied from the pipe or duct, 5, through which air is forced by a blower, 6, operated by a suitable motor, 7, there being, as shown in thisinstance, belts, 8-and 9, between the motor and blower, and between the motor and the preparing feeding appliances, by which these components of the'apparatus may be actuated at the proper speed according to the requirements at any time existing.

Referring now to Fig. 2, which shows the construction of the preparing and feeding mechanism located below the bin, 2,

and receiving the pulverized material therefrom by gravitation, said material passes down through the connecting passage, 20, into a chamber containing an agitator or distributor, 21, composed of blades or wings rotated in said chamber above the preparing mechanism, the active component of which upper edge,

is the rotating wheel, 30, by which the material coming from the bin is loosened, has any accumulations or lumps broken up, and is aerated so that when the particles have again settled into contact with one another the voids are large and freshly filled with air, and adjacent or contacting particles, are

not liable to adhere to one another to form lumps again.

From said preparing appliances, the detailed construction of which will be hereinafter described, the material descends by.

gravity into an intermediate settling chamber or receiver, 40, containing a rotating agitator and distributor, 41, similar in character to that in the upper chamber, and from this lower or accumulating chamber the material is delivered at the desired rate by the feeding device proper, shown as a wheel or rotating-component, 50, which, as shown in this instance, also serves in connection with tation over a second baffle plate, 62, the,

lower edge of which extends into-the airduct between the supply portion, 5, and delivery portion, 4, (see Fig. 1) so as to form a nozzle at 63, where the increased velocity of theair current thoroughly distributes 'the particles throughout the current flowing through the delivery tube, 4, in which they remain in suspension during the assage to the gas producer, furnace,-or' nal' delivery point at which 'the mixture of air and pulverized fuel is converted or consumed.

The lower bafiie plate, 62, is fixed-at its 64, and has sufiicient flexibility to admit of adjustment by an a justing bolt or link, 65, connected with its lower end and provided with external head, 66, for adjustment, to vary the area of the nozzle at 63, as may be found necessary or desirable.

Referring now to the construction of the preparing or preliminary conditioning device, or separating and aerating appliance,

best shown in Figs. 3 and 4, and in the upper portion of Fig. 2, the active component of said aeratlng appilance, as before stated, in this instance is a wheel, 30, having around its periphery fingers or teeth, 31, thus forming spaces or vpockets around the periphery between the teeth the two plates -or portions of pockets,

chamber above, so that the pulverized material would fall by gravity which, so far as the wheel itself is concerned, would be open at top and bottom, but closed or completed on three sides by the sides of the teeth and portion of the wheel periphery between them, and on the fourth side by. the wall of the chamber in which the wheel rotates, or a band or annulus which lines the wall at this point.

Cooperating with said rotating component, 30, are two plates, '32 and 33, one above and the other "(5 below the said wheel, and

each madein the form of an annulus having a flange, 34, lying just within the ma1 outer wall of the apparatus,

meeting and just surrounding the outer ends of the pocket forming teeth, 31, of the wheel.

Each plate extends inwardly from the periphery of the wheel a distance about equal to the length of the pocket forming teeth, the upper plate a little greater distance and the lower plate a little less, as clearly appears in Fig. 2, and each plate has recesses or apertures size to, or somewhat larger than the pockets between the teeth of the wheel, so that if the wheel were standing still in the proper position the upper plate would cover certain pockets or portions of pockets in the wheel and leave the intermediate pockets, uncovered or open to the supply into the uncovered pockets but would remain supported by the upper plate in the space between said uncovered pockets.

The lower plate is of similar construction but the open spaces in the lower plate lie beneath the non-recessed portion of the upper plate, so that with the wheelst anding, as above assumed, the lower plate would cover the bottoms of the pockets, or portions of pockets, left uncovered by the upper plate and thus receive and support the material permitted to fall through the upper plate into the pocket or space in the wheel. 7

When the wheel is rotating the teeth or pockets travel between the upper and lower plates and the pocket which is closed at the top by the a space or a recess in the lower plate, so that the material contained in said pocket can fall into the space or receiving chamber below, said'pocket at this time being covered by the upper plate so that no material enters it where thus discharging into the chamber below.

The feeding or forwarding action of the material from the chamber above to the chamber below the wheel will be readily understood, the pockets of the wheel receiving the material from above as they pass under the spaces or remsses in the upper plate, and discharging into the receiving about equal in' the flanges of upper plate is then passing over gravity.

chamber, 40, below as they pass over the spaces or recesses in the lower plate, and it will be recognized that the movement of the teeth of the wheel past the edges of the recesses in the plates will have a mechanical tendency to break up any lumps or aggregations of particles formed b the adherence together of the particles of material.

In addition to, and more important than, the mechanical effect of the teeth and plates in breakingup or reducing the lumps, is the separating and aerating effect which will now be described.

As the apparatus is all tightly closed except where open to the air atthe top, and delivers into air at approximately atmospheric pressure where the air current takes it, the pulverized material when falling from a pocket into the space or receiving chamber below will displace air which will enter the pocket substantially to the extent that said pocket is emptied of the aerated or loosely piled pulverized material falling from it, andsuch air coming up into the pocket from below must be displaced by the pulverized material entering from above. The wheel carries the air around with it, and the air thus encounters somewhat forcibly the powdered material coming down from above, with the result that the air is blown into the said entering material with more or less eddying or churning effect and thoroughly loosens and separates the particles, so that. they remain in suspension in the pocket or settle into the pocket in a light aerated condition, with each particle practically separated from all its neighbors by the air, thus assuring the maximum of air filled voids between theoparticles when settled and resting asa column or pile under the action of This aerating action gives the material delivered from it a light, flufi'y character, as

contrasted with the more dense and lumpy condition of the material compacted by gravity in the bin from which it is taken, and I have consequently called the active cpmponent a flufi'er wheel and the upper and lower plates which cooperate therewith to effect the aeration and produce the flufi'y condition, the upper and lower flufi'er plates.

The light, fluffy aerated material settlesinto the receiving chamber, 40, below the flufi'er wheel and is delivered therefrom by the discharge wheel, or feed wheel proper,

50, which is similar in construction to the" fiufi'er wheel. Said discharge wheel, 50, has peripheral teeth, 52, the spaces between which form pockets similar to those in the fiuffer wheel. All but a relatively small part of said pockets remain uncovered oropen to the space above, so that they rapidly fill with the material delivered into the intermediate chamber from the fluifer wheel,

the filling of the pockets being facilitated by the action of the agitator, 41 (see Fig. 4).

The pocketed periphery of said discharge wheel lies directly above a horizontal partition, 53, forming substantially the bottom of the portion of the apparatus containing the fiufling and feeding appliances thus far described, and said horizontal bottom portion is provided with a port or opening, 51, (see Fig. 6 and dotted lines Fig. 5), over the delivery passage, 60, through which the material falls by gravitation from the pockets into said delivery passage as the pockets successively pass over said port, 51, in the rotation of the wheel.

Said port, 51, is made of somewhat irregular shape, as shown in Fig. 6, being narrow and located towards the outer periphery of the wheel at the point where the pockets first come over the port in the rotation of the wheel and gradually widening to the full width of the pockets, with the result that the contents of the pocket are gradually and uniformly discharged into the outlet passage, 60, instead of being dumped in a mass as the pocket passes over the port.

An apron or closure, 54, is provided lying over the portion of the periphery of the feed wheel which is above the discharge port, 51, said apron thus closing the pockets at the top and supporting the material above them at the point where they are passing the discharge port, 51, and delivering'the material from the pockets therethrough. Said apron contributes to the uniform filling and packing of the material in the pockets as they enter beneath the apron before coming into communication with the discharge port, 51. Said apron is of suffithereto a worm wheel, 71, meshing with and adapted to be actuated by a worm, 72, driven by the shaft, 73, (see Fig. 1) at the desired speed, which may be varied automatically by any suitable regulating mechanism, or otherwise, according to the requirements, or rate of delivery of the pulverized material desired. I

Said worm gear and worm wheel are enclosed in a tight casing having a removable cover, 74, and" may run in a bath of oil contained in the lower part of the said casing,

.cover plates are provided,

which also serves to lubricate the bearing, 75, for the lower portion'of the-shaft, 70.

Above the driving gearing'and oil reser voir the shaft extends-through a bushing or bearing-,7 6, provided with suitable packing, 77 ,at its upper end above the bottom, 53, of the chamber, 40, and below the feedvwheel, 50, which discharges the material from said chamber, the driving mechanism and bearings being thus protected from entrance of the powdered material. I i

The feed wheel, 50, is loosely fitted upon the shaft 70, above the said packing, 77, and the lower distributor, 41, has a long sleeve-like hub also loosely fitted on the shaft and resting upon the hub. of the feed" wheel, 50. v

The flufi'er wheel 31, also has its hub loose upon the shaft, and the upper distributor, 21, has a sleeve-like hub also loose upon the shaft and resting upon the hub of the flufler wheel.

The several hubs of the feed wheel, fluifer Wheel, and distributors are interlocked for rotary movement by tongues or clutch teeth from the end of one hub entering recesses in the end of the adjacent hub, as shown in dotted line in Fig. 2, so that all of these components necessarily rotate in unison, and the power is transmitted from the shaft, 70, to them by a comparatively weak key or shear pin, 78, (see Figs. 2 and '3) which'connects the shaft, 70, with the sleeve-like hub of the upper distributor, 21, and affords an adequately strong connection for driving all of the parts under normah conditions, :but would be sheared off and releasethe driving shaft without breaking any of the parts, in case a solid piece were caught between the flufier wheel and plates or between the feed wheel and adjacent parts, or in case there should be any other accidental, obstruction at any point to the movement of the moving parts.

Suitable hand openings and removable as shown, where required, to aifordaccess to the internal components to the apparatus.

The lower end of the feed wheel shaft, 70, is shown as connected at 80, with a flexible shaft, 81, leading to a counting mechap nism, 82, of any suitable or usual constructi0n,'so that the apparatus whileserving to feed the material in proper condition to be thoroughly and uniformly distributed in the air current by which it is conveyed to the final delivery point, also serves as a meter for keeping account of the amount of material delivered.

The mechanical operatlon is" apparent,

from the foregoing description of the con-j struction. I

Power being applied to the blower, 6, the

current of air is forced through the pipes,.

; 5, 4, issuingas a flat jet from the nozzle, 63,

countering and entraining t is a substantially "secutively one at a time,

,tion of the aeratin of flufling appliance,

With a relatively high velocity and there ene particles of pulverized material falling .from thepreparing and feeding mechanism through the discharge passage, 60, and carrying the said particles suspended in a current of air through the portion of the duct beyond the nozzle and thence through the delivery pipe, 4, without swirling, and with uniform velocity, sufficient to prevent any settling of the particles to the bottom of the tube.

Power applied to the shaft, 73, causes the vertical shaft, 7 0, to rotate at a desired speed and rotates the several rotating elements supported on that shaft which act upon the material as it descends through or past them as has been described.

The relative arrangement of the flufi'er plates and fluffer wheel cause the do wnward movement of material to be intermittentat this point, although taken as a whole there constant downward movement of material above and below the wheel, and it will be recognized that substantially the entire contents of the wheel pockets will be, or may be, discharged in a rotary movement about equal to the space occupied by one recess and one intervening portion of the cover plate, so that in the proportion shown in Fig. 3 the entire contents of the wheel pockets will be discharged practicall twice at each rotation'of the wheel. r

In the case of the feed wheel, 50, however,

inasmuch as the pockets are emptied conthe entire contents of the pockets will be emptied only once for each rotation of the wheel.

Thus with the pocket capacity of the wheels about equal, as shown, the upper wheel will be capable of discharging a larger lower, and consequently quantity than the if the apparatus started from a stationary condition and was empty below the fluffer wheel and plates, the intermediate receiving chamber, 40, between the wheels 30, 50, would quickly fill to the top.

After said chamber is thus filled, obviously the upper wheel cannot, discharge more rapidly than the lower wheel takes away the material, and the result will be that the ockets in the upper wheel will not completely fill and empty as they pass the spaces in the flutter plates, and the air displaced by the portion of material which falls from the pocket will only partially fill the pocket.

The fiufiing effect described in connection with the descrput the material will fall through the upper flufier plate into the pocket as will serve to replace what has been discharged from it, and in so doing it will displace the air, which will have the desired churning and looseningefiect upon the material entering from above, and the only so much 0 will be such as has been buckets pass out from beneath the apron,"

54, a similar loosening and aerating eflect on the material entering the buckets, which must displace the air in them, so that the entering material and that somewhat above it will be more or less agitated, loosened, and lightened by action of the air at this point.

While it is diflicult to state just exactly what takes place in the aerating mechanism,

it is probable that the pockets of the fluifer.

wheel do not alternately completely fill and empty, but'remain more or less filled with eddying air, with the particles suspended in the air and continually settling therefrom onto the accumulated material below and entering from the more compact material above.

The having to a limited extent the loosening, or aerating action of the fiufi'er wheel and plates, travel a suflicient time incommunication with the spacev above, while closed below, to become filled with the material at v the density which it has when settling fliom ured with a considerable a condition of suspension in the air. The flufi'er wheel devices, serve to prepare the material, or bring the more or less compact and lumpy powdered material. to the condition in which its particles are separated and individually suspended in the air, and, so far as their condition is concerned, suitable to be carried by an air current to the point of consumption.

With such preliminary treatment alone it would be diflicult, or practically im ossible, to regulate closely the rate of eed, and consequently the prepa'red material is accumulated, or permitted to settle (except for the action of the distributor in the receiving chamber) and thus acquires a mass of uniform density capable of, being measdegree of accuracy and delivered at any desired rate within wide limits by a corresponding regulation of the speed of movement of the discharge wheel, without'loss of the quality required for suspension. in and uniform distribution throughout the conveying air current.

In the case of the preparing. and feeding appliances it is obviously immaterial,

pockets in the discharge wheel, while and plates, or aerating" except as a matter of mechanical convenience, which is the stationary and which the movable one of the relatively movable components. a

The method of treating the material involved in the operations hereinbefore described is particularly intended and peculiarly adapted for. the feeding of pulverized coal to furnaces employing such a fuel.

or best results such pulverized coal should be fed uniformly at any desired quantity rate, with the particles, which are minute, separated from one another so that when picked up and mixed with the air blast the result is in the nature of a cloud of fuel, with each coal particle individually suspended in and entirely surrounded by air for its combustion.

To accomplish thisresult in the operation hereinbefore described, the pulverized material, specificially coal, is advanced in mass by gravity to the apparatus, in which small portions of the coal are separated from the mass by permitting them to drop into the air trapped spaces or pocket chambers of the fiuffer wheel, in which dropping they displace some of the air, and the displaced air is forced up through the separated portions entering the pockets so as to disintegrate such portions and separate the particles of pulverized fuel and bring them individually into suspension in the air, from which they are permitted to settle.

Fuel in this condition is suitable for delivery to the furnace or to the air blast by which it is conveyed to the furnace and for this purpose the lower feed wheel, above described, feeds consecutively small separated'portions of the prepared and settled fuel to a point where they fall into'and are picked up by the air blast and form therewith the desired uniform cloud-like mixture of air and minute particles of pulverized coal, each such separated portion being at the lower end of saidchamber and a clos-- ure for the lower ends of the pockets, "except at one portion of their movement, said closure havinga discharge port longer than the peripheral length of one of the pockets 1 and narrower than the radial width of said pockets near one end and increasing to a ing width substantially equal to the radial width of the pockets at the other end, and I a closure above said wheel for the upper ends of said pockets while passing over said discharge port.

2. An apparatus for ing pulverized fuel, comprising a supply receptacle for said fuel and a passage leading down therefrom; preparin means for loosening the said material an placing its particles in suspension in the air; a receivpreparing appliance settle and accumulate at substantially uniform density; agitating devices in the supply space above, and the receiving chamber below the preparing means; feeding or discharging means for delivering said material from the said receiving chamber; a duct through which the powdered material falls; and an air duct with means for maintaining the flow of air therethrough' substantially in proportion to the amount of powdered material delivered for receiving the material thus delivered and conveying it in suspension to the point of consumption.

ERVIN G. BAILEY.

ISO

preparing and feedchamber in which the particles from the i

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