US2641369A - Crossfeed mechanism - Google Patents

Description

June 9, 1953 P. A. MULCEY ETAL CROSSFEED MECHANISM Filed March 2, 1951 2 Sheets-Sheet 1 P. A- MULCEY ET AL CROSSFEED MECHANISM June 9, 1953 Filed March 2, 1951 2 Sheets-She et 2 Patented June 9, 1953 UNITED STATES PATENT oselcs Paul A. Mulcey, Dallas, J ames w. Eckerd,.Shavertown, and Edward 1. Small, :SJcrantIomLPa assignors hraci e E ui me t- Cor oratio ":JJW 1?'R z -P a er ie .p .l awa Appeasemen enr tatin 3 Claims. c1i 214-721) The present invention relates'generally t the feeding o'f 'granula'r solid material or sludge for now over a surface, and more particularly'to the feeding of coal by a 'crossfeed Stoker.

ln' cr'ossfeed mechanisms fordelivering material to *a horizontally dis'posed surface I the problem, heretofore,-ha5 been to so deliver the material that it will flow uniformly and of even depth across such surface. Thi's problem has been particularly troublesome where coal iis stoker-fe'd'to a retort having arectangu'lar grate, because a non-uniform or uneven fire'b'ed results in spot combustiondue to the induced draft breaking throughthin areas of the bed. Thus, in some areas complete combustion mayILtake place while in others there is incompletechmbustion and a severe 105s in efficient ioperation.

One of the objects-of the present invention is to provide an emcient crossfeed mechanism for feeding granular solid material .to a surface.

Another object of the inventionis rtoiprovide a crossfeed mechanism for delivering material at auniform rate to a surface. 4

Another object of the invention is to provide a crossfeed mechanism for deliveringmaterial evenly over a surface.

Another object of the invention is .to.-;provide a coal-distributing mechanism-for a .icrossfeed stoker wherein the coalleavesthe'mechanism at a uniform rate and of even Idepthasidelivered to a rectangular grate.

Another object of the inventioniis toi'iprovide a coal-feeding and distributing v.mechanism wherein a novelv assemblyfof .concentr'icscrew flights operates upon :ooalfto causeit. .to flow over a grate at a co'ntrolledrate.

Another object, of the. invention isto provide a coal-feeding and distributing mechanism wherein a novellasseinbly of concentric screw flights, having a corrirnontdrivingmeans, operi ates to feed coal lengthwise of autube, a,,p0rtion of the coal-feedingjin. one direction, another portion feeding in the opposite: direction, and all the coal flowing away from..the;axis,of the coal to dischargeupon a grate at an even rate of advance.

ther objects will appear hereinafter.

In the accompanyingdrawings, Fig. l represents a plan in part section of a coal-feeding mechanismembodying one form. of the present invention, shown "in a'ssoiation with a' crossfeed grate of acoal-burning retqrtgFig. 2 represents a section on line 22 of Fig. 1; Fig 3 represents a side elevation partly broken away of the coal-feeder and distributing tubeg figi 4 represents a section on lined-4 of l-iig. 3'; Fig. 5 represents an end elevation of" the feeder 'and distributingtubej Fig. 6 represents aside-"elevati-on' of I the combined -picli- 'up screw"and excess return screw; Fig? '7- represents a 'side' ele- .12 vation of the auxiliary feeder screw with an'excess re'turn screw" and attached dis'tributing paddles; .i 4

Referring to the drawings, one form of .th present invention is' shownas operating in conjunction 'withfa' stoker-fired retort Ii) having a rectangular grate l l disposed over a wind box l2 supplied'w'ith a'ir' through a duct 53 from a fan'blower (not shown) 'Ihe retort and the use of coal is only by way "of illustration, as the feeding mechanism of the invention includes a wide range of granular solid material or sludge, which can be delivered toany surface over which auniform "distributionfof material isdes'ired.

Inthe, present -instance the' feeding mechanism .of the invention comprises a tube I l mounted atthe receiving end'of the grate H and having a side outlet 15 extending lengthwise of the tube l l'to discharge into a conduit It as alat'eral continuation'of the outlet-J5. Thenfloor i? of theconduit 15 preferably lies substantially in the plane of .the grate H. obviously the'outlet 15 can be mounted to discharge directly upon'a surface, but'ithe present length showing of the conduit I6 is to provide a lateral space'foriit to pass underthe water leg of a boiler.

ATh'e tube l 4 is-closed at oneiend by a removable plateulil' mounting'an axially alined bearinglfl, and opens'at-the opposite end-through an ape'rtured plate/2| for. cor'rimunication'with a coal supply 'fpipeim! which leads to a source ofcoal. Thefeed forthe'coalfrom this sourc'athrough the piped 2,is by means of a pick-up screw comprising left hand flights'i23 woundspirally about and attached to a-driven' shaft 24 which, continues axially? through the tube. l4, whereits endprojects-through the bearing 2t to mount adriven sprocket'zli. It should be noted, however', .thatitheflights .23 terminate adjacent the inlet to' the. tube M 'or preferably just within such inlet in order that'the feed can be transferred to an auxiliary. feeder screw of larger'diameter left hand flights l26"a1so wound about the shaft'2 l butinter'rially radially spaced from the shaft 24 tov provide an annular clearance for a purpose to 'be presently. described. 'Attention is dire'ctedto the factthati the end flight r21 of this auxiliary screw adjacent the closed end of the tube I4 is a right hand convolution which acts to. initially start a reverse or return feed of 'e'xcess coalthrough thelaforesaid annular clearance This prevents packing and improper pil- Ting upbf co'alatthe closed end of the tubeM. In order to bring about an even or uniform distribution ,ofpthe .coal through. the (outlet; l5, ahthird feed screw, is, {provided having right hand. lj eh s dwoundi q an a ta h to h shaft ,24, to,;;pass,. alongithe, annular clearance formedt eeflie g fi d ye t e flights 28, are so; dimensioned,-,that. rt o eiwiihin on or more of the flights 26 provide contact points for spot welding whereby rotary motion of the shaft 24 is transmitted to the left hand feeder screw formed by the flights 26. Thus, rotation of the shaft 24 drives the flights 23 and 25 in the direction to feed coal into and along the tube 14 and the single flight 2'! and the flights- 28 causes a feed in the opposite direction. From the foregoing it will be seen that the tube It houses a pair of concentric screw flights having opposite directions of pitch, the inner flight being wound on the drive shaft and secured thereto, while the outer flight is secured to the inner flight. Furthermore, the invention is not to be limited to the specific right and left hand arrangement of the flights, because such depend upon the direction of turning of the shaft 24. The present showing is the preferred construction in accordance with-the direction of rotation of the shaft 24 as indicated by the arrow.

As a means to further promote even distribution throughout the length of the tube It, a, plurality of vanes or paddles 30 are attached to the screw flights 26 so as to be contained within the outer diameter of such flights 26. As shown, each vane straddles the space between, a pair of the flights 26 and is preferably, but, not necessarily, of arcuate configuration with its convex face disposed in the direction oftravel of the flights 25. In the preferred form these vanes 30 are in alined relation parallel to the axis of the flights 26, but this is only by way of illustration, since the object is. to pick-up coal between each pair, of flights and deliver it effectively to the outlet 15 as a delivery supplementing the flow from the flights. The invention is not to be limited, however, to the number of such vanes, as it has been found that using a single vane in a particular place has given satisfactory results.

In the operation of the crossfeedmechanism, the coal or other granular solid material is delivered to the open end of the tube it by any suitable feed device, which, in this instance, is the pick-up screw in the pipe 22, where it is picked up by the flights 26 having the dual function of feeding the coal lengthwise of the tube I4 while advancing also laterally to discharge through the outlet side of outlet I5 onto the grate H, or in this instance, into the conduit l6 leading to the grate. As the tube M 'fllls with coal, the excess reaches the closed end of the tube I4, where the flight 27 reverses the coal flow and directs it into the path of the return feed flights 28, which convey this excess lengthwise within the flights 26 where it mingles withthe incoming coal and leaves as a combined flow through the outlet [5. The relative proportioning of the feeding, return flights, and vanes is a precision one, whereby an even, uniform layer of coal emerges from the side of the tube l4 and is caused to travel at a controlled rate onto and across the grate of a coalburning retort.

It will now be apparent that a complete unitary crossfeed mechanism for granular solid fuel has been devised wherein all parts of one moving unit are rigidly secured together and so function as to produce a result not heretofore attainable by a crossfeed mechanism. This result gives the following advantages: the rate of conveying is readily controlled; the pattern distribution can be controlled by design; a minimum amount of degradation is produced; the mechanism operates quietly; it can convey and distribute a varying range of material sizes, forms, and composition; it distributes material without size classification or segregation; power requirements are low; the construction is simple; requires no auxiliary mechanism for satisfactory operation; and is adaptable to variations in longitudinal dimension without disturbing distribution patterns.

Having thus described our claim: 1

1. A crossfeed mechanism for delivering material to an adjacent horizontally disposed rectangular grate, comprising a tube having a lengthwise disposed side outlet extending throughout substantially the length of said tube, and an inlet for material at one end, said outlet adapted to lead to said grate throughout substantially one side thereof, a shaft rotatably mountedin said tube parallel to said outlet, and two concentrically mounted feed screws operated by said shaft, said screws being parallel to said outlet and coextensive with respect thereto, one of said screws feeding a material delivered to said inlet in one direction lengthwise to discharge laterally through said outlet, and the other of said feed screws feeding excess material in the opposite direction to discharge laterally through said outlet, and one of said screws carrying a row of vanes in registering relation to said outlet to eject material to said outlet.

2. A crossfeed mechanism for delivering material to an adjacent horizontally disposed rectangular grate, comprising a closed end tube having an inlet at the opposite end and an outlet lengthwise of one side parallel to the axis of said tube, adapted to lead to said grate throughout substantially one side of said grate, a shaft rotatably mounted lengthwise within said tube, a screw having left hand flights coextensive with said outlet for feeding material away from said inlet and across said outlet and at least one right hand flight for returning material towards said inlet, a second screw having right hand flights coextensive with said outlet for returning material towards said inlet and across said outlet, said two screws being mounted on said shaft in overlapping relation, a plurality of radially disposed material-propelling vanes carried by one of said screws, said vanes being coextensive with said outlet, and means for transmitting rotary motion of said shaft to both screws, whereby said screws coact to deliver material to said outlet.

3. A crossfeed mechanism in accordance with claim 2 wherein the propelling vanes are mounted respectively between pairs of flights of one of said screws and laterally alined with said outlet.

invention, we

PAUL A. MULCEY..

JAMES W. ECKERD.

EDWARD I. SMALL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,525,506 Lauterbur Feb. 10, 1925 2,142,701 Skelly Jan. 3, 1939 2,208,757 Fitch July 23, 1940 2,255,481 Crowley Sept. 9, 1941 2,332,688 Baily Oct. 26, 1943 2,390,680 Ausherman i Dec. 11, 19 15

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