US2428874A

US2428874A - Reciprocating bar grate

Info

Publication number: US2428874A
Authority: US
Publication date: 1947-10-14
Anticipated expiration: 1964-10-14

Description

2 Sheets-Sheet 1v Oct. 14, 1947. 1 F. GQUGH` RECIPROCATING BAR GRATE Filed June 25, 1945 Oct. 14,1947. LEGOUGH 2,428,874

RECIPROCATING BAR GRATE Filed June 25, 1945 2 Shvees-SheecI 2 i VII i f Patented Oct. '14, 1947 UNITED STATES PATENT OFFICE REoiPnocATiNo BAR GRATE Leslie F. Gough, Toronto, ontariaoanaaaf applicati@ June. 2.5, isfiafseriainn.' 601,403

2 Claims. (Cl. l10n-38)r My invention relates to improvements in grates of combustion chambers for industrial heating plants .andthe like, and particularly concerns an underfeed combustion chamber in which coal is upwardly delivered to the grate or grates by a stoker unit. f

In mechanically red furnaces of the prior art structures the distribution of the fuel over the entire grate area and lthe movement of the burned-out refuse onto the side dumping `grates is mainly dependent upon agitation of alternate grate bars of a row.v Such a construction, although suitable forpburning bituminous coal, is not adapted for effectively burning anthracite coal.

` Hence it is the object of the present invention to provide a grate structure of this character which will effectively burn anthracite screenings as well as different grades of bituminous coal, and one which is not only efficient and reliable in operation but is also simple in construction and inexpensive to manufacture.

The invention comprehends the novel construction and arrangement of the grate bars and the mechanical means by which the grate bars are operated to maintain a level and porous fuel bed and to rassure of gradual movement of the burning fuel toward the dumping grates.

Having recounted the primary objects ofthe invention,.subsidiary objects and advantages will appear as the inven-tion is set out in detail in the ensuing specification withreference to the accompanying drawings in which a selected embodiment of the apparatus is shown by way of illustration but not of limitation.

In the drawings,

Fig. 1 is a fractional plan view of a combustion chamber of a furnace showing the improved grate construction.

Fig. 2 is a sectional elevation thereof.

Fig. 3 is a cross section on line 3-3 oi Fig. 2.

Fig. 4 is a view looking at the front of the furnace and showing the drive mechanism Vfor the grate bars;

Fig. 5 is a detail of a drive sprocket depicting a device thereon by which the movement of the grate bars can be shortened and lengthened.

Fig. 6 is a front edge view of a grate bar.

Fig. 7. is an enlarged sectional view of a roller and groove forming a bearing for a gratel bar.

The drawing is illustrative of a furnace provided with a side retort, i. e., a retort disposed at a side wall of the combustion chamber. It will be understood however that the invention is also susceptible of use with a centre retort.

The retort, denoted atl 8, may be oi an ordinary construction, and as customary extends from the front wall 9 ofthe combustion chamber l0 to the rear wall thereof (not shown) and is disposed at a side wall, denoted at H, the other side wal-1 being indicated at I2. The retort is, ofcourse, apart of the regular Stoker unit and is equipped withY reciprocal rams, as at I3, for the feeding of coal upwardly onto the grate. The trough of the stoker through which the coal is delivered tothe retort is shown at i4 in Fig. 1.

In carrying outthe invention there is provided a seri-es4 of grate bars extending forwardly from a side of the retort 8 to the usual dumping grates l5. Said grate barsydenoted'at I6; are arranged in overlapping manner and the front ends of' each set or row restupon the rear ends ofy an: adjacent set or row. Thus there is provided a grate surface of' asteppedfo-rmation formed by the several rows'ror courses of' bars. The complemental bars of each row orV course are placed in side-by-side relation to extend between the-front and rear walls of the combustion chamber and each set runs parallel-ly to the retort. y

The grate surface Vslopes at a general gradual declivity toward the wall l2 remote of the retort andthe'grate bars of the uppermost set have their rear ends seated vupon the adjoining side wall of the retort 8. The rear ends of the other sets of bars and also the front ends of the foremost Vset of bars are 'preferably sustained by means of anti-friction bearings.y Each of these loearingscomprisesa'roller l1 loosely mounted in a groove I8y of a vfshaped cross section provided in a beam i9 extending' between the front and rear walls of the combustion chamber. The roller extends the full length of a set of bars and upwardly projects from said groove so as to have Iseating contact Awi-ththe bottom faces of the bars.

rihe bearings support the bars for reciprocal movement as will later be explained.

The grate bars are of identical construction and eachis a hollow casting having a at'b'ottom wall 20 and a top wall 2l which slopes upwardly from -the front edge 22 toward the rear wall 23 and terminates in a short flat section 23 which forms a bearing area for the front end of the grate bar that'rests. thereupon. The sloping section of the top wall;v is supplied, with longitudinally extending ribs 24 suitably spaced for guiding the4 fuel forwardly. The ribs are preferably of a V-shape in cross section and perforated as at 25 to provide air passage to assure of an adequate distribution of air throughout the bed of coal. Said front edge 22 is also preferably provided with air ports as at 26 and these are shown as square holes. Induction ports may be suitably provided in the bar for introducing air therein from the ordinary forced draft so that it will flow out of the

openings

25 and 26. Any desirable ramication of induction ports may be provided such as those indicated at 21 in the rear wall 23.

The bars of each set or row may be recessed as at 28 to form an intertting connection with an adjacent bar, and in order that the component bars of each set or row may be connected as a unit for reciprocal movement there is provided a rod 29 of a length to extend thereacross. The rod is seated in open-end slots formed by the elements 30 on the bottom Wall 20.

A rock shaft 3| is used to reciprocate each set or row of the grate bars, and to this end it is arranged below the same and journalled in the front and rear walls of the combustion chamber. On the rock shaft there is a longitudinal series of rigid lingers 32 which are individually engaged in slots formed by lugs 33 on the bottom walls 20 of the bars. It will be obvious that by this construction the bars are moved to and fro by scillatory actuation of the rock shaft. The rock shafts of the several sets of grate bars project forwardly of the front wall 9 and are provided with aligned sprockets 34, and in association with said sprocket there is provided a drive sprocket 35 therefor.

Said drive sprocket is oscillated by a fluid cylinder 36 or other motivating agent. Said cylinder is of the double-acting type in which the ports are controlled by a valve 31 actuated by a lever 38. The piston-rod 39 has a crosshead 40 connected to a pitman 4I which in turn is connected to said drive sprocket which is provided with a device for operating the valve-lever 38. Said device comprises a slide rod 42 having spaced arms 43 disposed in the arc of movement of a pin 44 on said drive sprocket. When the drive sprocket is turned in one direction the said pin contacts an arm of the slide rod 42 and shifts it fo-r reversal of the piston and the other arm is similarly actuated to reverse the piston at the other end of its stroke. A chain 45 connects the drive sprocket 35 to the sprockets 34 and has one run or reach alternately trained over and under the sprockets 34 between its ends so that adjacent rock shafts will be reversely oscillated.

It will be manifest by this arrangement that alternate rows or sets of grate bars are caused to be moved reversely to the others in each stroke of their reciprocation. Consequently as one set of grate bars moves forwardly to advance burning fuel onto an adjacent set the adjacent set moves backwardiy which produces an effective feeding action which tends to spread the fuel uniformly as the adjacent sets of bars move away from each other in a reversal of their movements. By this action the fuel is caused to be gradually fed over the sloping grate surface from the retort to the dumping grates. Y

Mechanism is provided to adjust the reciprocal movement of the grate bars. Such means comprises devices by which the sprockets 34 are connected to the respective rock shafts. The sprockets are loosely mounted on the rock shafts and provided with radial screws 46 each having an inner head 41 adapted t0 be moved to and away from a side of a fixed block 48. The blocks are pinned on the shafts and it will be understood that when the screws are tightened to firmly engage their heads therewith the rock shafts turn as one with their sprockets. However, by slackening off the screw so that their heads are spaced from the blocks but disposed within the orbit described by the corners thereof the sprockets are adapted to turn with an amount of lost motion with respect to the rock shafts according to the spacing of the heads from the adjoining sides of respective blocks. This construction is a simple mode of varying the amount of movement imparted to the grate bars by the gearing.

The invention provides an improved grate structure which is particularly adapted for industrial installation and is susceptible of such changes and modication as come within the scope of the subjoined claims.

What I claim is:

1. In a furnace having means for feeding solid fuel upwardly, a grate extending forwardly from a side of said means comprising a plurality of bars arranged in sets or courses parallel to one another, the bars of each set being disposed alongside each other and the front ends of bars of one set overlying the rear ends of bars of an adjacent set, means for sustaining said sets of bars, a rock shaft mounted below each set of bars, means by which oscillatory movement of the rock shafts reciprocates the set of bars, and means for connecting the rock shafts to a motivating agent. the means for connecting the rock shafts to a motivating agent consisting of a sprocket and chain drive including a drive sprocket and characterized in that a run or stretch of the chain is trained over one sprocket and under another in a manner to oscillate alternate rock shafts re- Versely to the others.

2. In a furnace of the kind described provided with rock shafts and a grate having overlapping bars movably supported for reciprocation by oscillatory movement of said rock shafts; the improvement comprising means for connecting the rock shafts to a motivating agent, said means consisting of a sprocket and chain drive including a drive sprocket and characterized in that a run or stretch of the chain is trained over one sprocketY and under another in a manner to oscillate alternate rock shafts reversely to the others.

LESLIE F'. GOUGH.

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

UNITED STATES PATENTS Number Name Date 689,827 McClave Dec. 24, 1901 859,413 Small July 9, 1907 1,048,356 Seaton Dec. 24, 1912 1 522,917 Skelly Jan. 13, 1925 1,564,813 Babendreier Dec. 8, 1925 1,644,953 Seyboth Oct. 11, 1927 1,913,396 Kay June 13, 1933 FOREIGN PATENTS Number Country Date.

309,459 Great Britain July 2, 1928 377,224 Germany July 7, 1928