US2146557A - Grate bar - Google Patents

Description

o, L. BARDESF ET AL 2,146,557

Feb. 7,' 1939.

GRATE BAR Filed April 27, 1936 OLNER L. BARDES in THOMAS F- FRASER.

Patented Feb. 7, 1939 GRATE BAR Oliver L. Bardes and Thomas F. Fraser, Cincinnati, Ohio, assignors to The E. H. Bardes Range'& Foundry Company, Cincinnati, Ohio,

a corporation ofOhio Application April 2'1, 1936, Serial No. 76,578

4 Claims.

This invention relates generally to the grate structures employed in furnaces equipped with automatic coal-feeding mechanism and provided with means for introducing air under pressure 5 into'the fuel-bed. It has particular reference to the grate bars which constitute that portion of the fuel-bed str ucture commonly known as the extension grates in multiple retort furnaces and which are usually disposed directly to the rear of the tuyres and retorts. 'It is in this portion of the fuel-bed that the complete burning of the coal is finally accomplished and the residuum subsequently dis pit. Therefore,

charged therefrom into the ashin order to consume every parcondition of the it is desirable to effect the maximum of activity fuel at this stage of combustion,

in this portion of the fuel-bed so as to accomplish the fullest measure of combustion. To this end, it is common practice to impart a reciprocatory up insofar as is movement to the extension grates so as to break possible the cohesion of the fuel particles and thus enable the air currents to more readily penetrate the mass of burning embers.

Inasmuch as the grate bars in this part of the fuel-bed are directly exposed to the intense heat of the incandescent fuel and consequently are subject to rapid depreciation, it is of the utmost importance that every precaution be taken and every provision be made in the design of such bars as to assure and facilitate cooling of the 'bars by the air currents and thus obtain the maximum of radiation of the heat so as to prolong the life of possible.

the bars to the greatest extent In view of these circumstances, one object of the present invention is to provide a grate bar for the extension grates which will effect a greater activity in the combustion of the fuel supported thereon. sible with bars prior practice.

Another object is to provide a grate bar for this purpose wh of radiation or the bar.

.Another object is to provide a grate bar of than has heretofore been posconstructed in accordance with ich will accomplish a maximum diffusion of the heat away from this character. which will withstand the intense heat and fluctuating temperature without undue distortion Another .objec t to provide for maintaining a substantial circulation of air between adjacent bars if and when any of the air passageways become temporarily choked at the outlet by ash or other matter.

Another object is to provide a grate bar of this character having a fuel-supporting surface which is arranged so as to facilitate the maintenance of a disintegrated condition of the fuel-bed.

These and other objects will be apparent from the following description and accompanying drawing, in which: 7

Fig. 1 is a side sectional elevation of the extension grate structure, taken substantially on a line II of Fig. 2.

Fig. 2 is an elevation of one of the group units of the extension grate as viewed from the psition 2-2, Fig. 1. v

Fig. 3 is a sectional view of several of the center grate bars as taken on a line 33, Fig. 1.

Fig. 4 is a sectional view of several of the center grate bars and one end bar as taken on a. line 44, Fig. 1.

Fig. 5 is a sectional view of the same bars as shown in Fig. 4 but taken on a' line 55, Fig. 1.

Fig. 6 is a side elevation of the end grate bar on a reduced scale.

Fig. 7 is a bottom view of the end grate bar shown in Fig. 6.

Inasmuch as the invention disclosed herein. pertains only to the grate bars of the extension grate structure, no illustration or description need. be given of the coal feeding mechanism or of the other elements of the furnace structure such as the retorts, tuyres, etc.

Referring to the drawing:the extension grate structure is shown as comprising a plurality of grate bars and a supporting framework for the group. As shown in Fig. 2,- each group of grate bars consists of center bars ill and end bars I I. Preferably all of the bars have substantially the same general profile in side elevation, each center bar comprising a horizontal portion Illa, a Vertical portion 10b and an intermediate inclined portion I00 and each end bar having similar portions Ha, lib and I I0 respectively, butin certain other respects, the end bars are preferably different from the center bars- However all center bars are alike and all end bars are alike. As shown in Figs. 1 to'5, the center bars Iii are solid, and, as shown in Figs. 4 to '7, the end bars I I are grooved on the bottom or forward side so that the cross-sectional form of the bar is like that of a channel.

As shown in Figs. 1 to 5, portion 10c of each center bar is provided with a plurality of horizontally disposed ribs or flanges E2 on side face 13 and a plurality of similar flanges M are provided on the opposite face lo, the said flanges on one side being disposed in horizontal planes which alternate with the flanges on the opposite side so that, in assembly, the flanges on adjacent sides of the bars will overlap alternately, as shown in Figs. 2, 3 and 5, thereby effecting air passageways between the adjacent bars and at the same time baffiing the transit of ash dust downward between the bars, as illustrated in Fig. 2. Preferably flanges l2 and Id extend from-the top or rear face N5 of portion illc of the bar to substantially near the bottom or forward face i1 thereof and faces I3 and i5 of portion lilo are preferably provided with grooves l8 and I9 re-' spectively on each side of each of said flanges, said grooves being spaced vertically and extending from a point near the face 16 to a point near the face H, said grooves having greater depth at one end than at the other as clearly shown in Fig 3, the arrangement being such that the portions of side faces l3 and .I'dbetween the grooves register in assembly with the respective flanges l2 and I l onadjacent bars. 7

Each of the flanges l2 and la is provided with a lateral passageway or notch !2a and Ma respectively, preferably located nearthe rear end of the flange, and the purpose of this notch will be hereinafter referred to.

The top or rear face 16 of portion lflc, which is a fuel-supporting surface, is arranged with a plurality of facets so as to provide in effect a series of steps 20 and the disposition of these steps is arranged relative to the flanges l2 and is so that the outlets of the air passageways formed between the overlapping flanges of ad jacent bars will have an advantageous cooperative relation with thefunctional effect of the said steps as hereinafter referred to.

The horizontal portion llla, of the center bars is provided with a horizontal flange 2% on one of the side faces and a flange 22 on the other side face, these flanges being disposed in different vertical planes so as to overlap one another in assembly as shown in Figs. 2 and 4. Preferably the flange 22 is flush with the upper face 23 of portion Illa and extends forward from the face IE to the forward end of said portion while flange 2! extends rearward from the said forward end to a point spaced forward of face l5.

The vertical portion lilb of the center bars is also provided on one of the side faces with a plurality of horizontally disposed ribs Or flanges 2 4 and a like number of similar flanges 25 on the other side face, these flanges being arranged in vertical series so that in assembly flanges 2A are in abutting relation with flanges 25 thus forming air passageways between adjacent bars as shown in Fig. 2.

In reference to end bars litthe top or rear face 26 of portion lie is arranged in a series of steps 21 similar to the face it of bar ID but the side faces 28 and 29 are preferably devoid of flanges throughout the extent of portions llb and lie, the former having merely a spacing abutment 30 on each side face, while portion Ha is provided with flanges 3| and 32 sirnilar to flanges 2i and 22 on bar l0. However, bar H is provided with a plurality of air passageways in the form of apertures 33 extending through the upper wallof the bar and these passageways are disposed relative to the steps'Zl so as to cooperate functionally therewith in a manner hereinafter referred to.

- the purpose.

The grate bars of each group are arranged so that they may be detachably mounted upon a supporting framework. This arrangement may be of any suitable character but we have herein shown a framework comprising side plates 34 and 35 rigidly secured one to the other by means of tie members to and 31 and each bar is provided with a hook portion 38 whereby the lower or rear end of the bar may effect engagement with tie member 36 which is suitably formed for Moreover each of the center bars ll) is shown as having a web portion 39 and a recess 40 on each side of said web and. tie member 31 is shown as formed with a series of prongs ll each of which is disposed between the webs 39 and within the recesses G8 on adjacent bars thereby defining the position of the upper end of each of said bars whereas end bars l I are each provided with a lug portion 52 which engages a recess 43 in each of the respective side plates 34 and 35 while the channel formation of the said end bars enables them to be nested upon or to straddle the side plate and thus the end bars are held in position both longitudinally and laterally.

The supporting framework carrying a group of grate bars may be arranged so as to be reciprocated bodily in any suitable manner but we have herein shown fixed guideways 44 and 45 in which the side plates 34 and 35 of the framework are slidably mounted and motion may be imparted to the framework by operatively connecting it with the coal feeding mechanism of the stoker (not shown) in any well known manner as by push-pull rods ie which may be attached to any part of the framework such as brackets 31 secured to the side plates.

In operation, draft air is supplied to the space below and forward of the grate bars and, as shown by the arrows in Fig. 1, the air flows in a generally rearward and upward direction passing through the air passageways between the grate bars and through the apertures 33 in the end bars and thus the burning fuel carried by the extension grates is supplied with a multiplicity of air currents disposed in a substantially uniform manner throughout the extent of the grate area.

It will be observed that the formation of the grate bars issuch as to enhance the effectiveness of the. air currents in carrying the heat away from the bars thus avoiding excessively destructive temperature and thereby preserving the service life of the grate bar to the greatest extent. However, should the air outlet to any of the air passageways between the bars become temporarily clogged, as by ash or otherwise, circulation of air throughout a substantial portion of the closed passageway may still be maintained by means of the notch l2a or I la in the flanges l2 and I4 and this feature has been found to be of distinct advantage in avoiding destructive hot-spots arising from closed air outlets.

The molten-like condition of the burning fuel carried by the extension grates often acts to give the effect of blanketing or choking the air currents emerging from the passageways through and between the bars and this retards the rate of combustion-that is, reduces the activity of the fire. To alleviate this condition, it has been common practice to give the extension grates a horizontal reciprocatory movement, the idea being to thus cause disintegration of the coherent mass of fuel and thus release the air currents but this method has been only partially successful in accomplishing a suflicient degree of has cent bars; each o :sai wfl n es being provid activity; mainly because the fuelasupporting surgface of the-extension grate bars has heretofore been disposed in a single angular plane and further because most of 1 the commonly used grades of coal fuse so completely during the later stages of combustion that a, smooth fuelsupporting surface is ineffectual to. disrupt the mass; In order tojeffectan improvement in this condition, ,we have provided the extension grate bars with an irregular or offset fuel-supporting surface in the form of a series of steps and it is this feature which assures that the fused layer of coal will be broken up when the extension grates are moved back and forth. The result thus obtained represents not only a substantial increase in the efficiency of combustion due to the greater activity of the fire but it is an important factor in prolonging the life of the grate bars because of the greater rapidity with which the heat is carried away from the bars by the freer flow of air.

Particular attention is also directed to the advantageous results obtained by arranging the air passageways so as to have a. definite cooperative relationship with the offsets or steps 20 and 21 in the fuel-supporting surface of the bars. As shown in Fig. 2, it will be noted that, in the assembly of the center bars, there are threeair passageways associated with each step; one directly in horizontal alignment with the vertical face of the step; another just above the step, and the other just below the step. In substantially like manner, the air passageways 33 in the end bars H are disposed one above and one below each of the steps 21. This particular arrangement causes the air currents to be discharged into the fuel directly at those points where they willbe most effective, that is, where the fused layer of embers has been fractured by the offsets in the fuel-supporting surface. In this way the final stage of combustion is accomplished in a more highly efficient and thorough manner than has been possible heretofore.

It is thus apparent that we have provided a grate bar which accomplishes the objectives set forth herein and one which represents a substantial improvement over bars constructed in accordance with prior practice.

It is obvious that the novel features disclosed may be variously modified as to form and as to application in grate bars of similar character in general and it is to be'understood that the invention is limited not by the particular form of con struction shown herein but only by the scope of the following claims.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. Grate bars adapted for horizontal reciprocation in assembly with like bars arranged side by side, said bars,-in operative position, comprising a solid inclined portion having a relatively narrow and imperforate rear face exposed to the fire and relatively wide side faces, said rear face being composed of longitudinally alternating vertical and slopingfacets which extend fully fro-m one side face to the other, and each of said side faces arranged with a plurality of substantially horizontal flanges extending from said rear face to a point near the opposite face of said inclined portion, the flanges on one of said side faces being disposed in horizontal planes alternating with those on the other side face so as to provide in assembly substantial air passageways formed by the overlapping flanges between adja- With a crosswise passageway which effectscommunicationbetween the air passageways on opposite sides of said flanges.

2. Grate-bars adapted for horizontal reciprocation in assembly with like bars arranged side by side, said bars, in operative position, compris ing a solidinclined portion having a relatively narrow and imperforate rear face exposed to the fire and relatively wide side faces, said rear face being composed of longitudinally alternating vertical and sloping facets which extend fully from one side face .to the other, and each of said side faces arranged with a plurality of substantially horizontal flanges extending from said rear face to a point near the opposite face of said inclined portion, the flanges on one of said side faces being disposed in horizontal planes alternating with those on the other side face so as to provide in assembly substantial air passageways formed by the overlapping flanges between adjacent bars, said flanges being further disposed so as to provide a passageway in direct horizontal alignment with each of said vertical facets, another passageway above and still another passageway below each of said vertical facets, each of said flanges being provided with a crosswise passageway which effects communication between the air passageways on opposite sides of said flanges.

3. In an extension grate structure in combi- I nation with a supporting framework adapted to be reciprocated horizontally, a group of grate bars attached to said framework and disposed in side-to-side relation, said group comprising end bars grooved longitudinally on the underside to receive the side members of said framework and a plurality of other bars positioned intermediate said end bars, each of said bars, in operative position, comprising an inclined portion having a relatively narrow rear face exposed to the fire and relatively wide side faces, said rear face being composed of longitudinally alternating vertical and sloping facets which extend fully from one side face to the other, a plurality of substantially horizontal flanges arranged on each of the side faces of said intermediate bars and extending from said rear face to a point near the opposite face of said inclined portion, the flanges on one of said side faces being disposed in horizontal planes alternating with those on the other side face so as to provide air passageways formed by the overlapping flanges between adjacent bars, and a longitudinally disposed series of apertures extending through the inclined portion of said end bars from said sloping facets to the groove on the underside thereof.

4. In an extension grate structure in combination with a supporting framework adapted to be reciprocated horizontally, a group of grate bars attached to said framework and disposed in sideto-side relation, said group comprising end bars grooved longitudinally on the underside to receive the side members of said framework and a plurality of other bars positioned intermediate said end bars, each of said bars, in operative position, comprising an inclined portion having a relatively narrow rear face exposed to the fire and relatively wide side faces, said rear face being composed of longitudinally alternating vertical and sloping facets which extend fully from one side face to the other, a plurality of substantially horizontal flanges arranged on each of the side faces of said intermediate bars'and extending from said rear face to a point near the opposite face of said inclined portion, the flanges on, one of said side faces being disposed in horizontal planes alternating with those on the other side face so as to provide air passageways formed by the overlapping flanges between adjacent bars, said flanges being further disposed so as to provide a passageway indirect horizontal alignment with each of said vertical facets, another passageway above and still another passageway below each of said vertical facets, and a longitudinally disposed series of apertures extending through the inclined portion of said end bars from said sloping facets to the groove on the underside thereof, the said apertures being positioned one above and one below each of said vertical facets.

OLIVER L. BARDES.

THOMAS F. FRASER.

Images