US1959117A - Grate construction - Google Patents

Description

May 15, 1934. J. 5. THOMPSON 1,959,117

GRATE CONSTRUCTION Filed Feb. 25, 1930 3 Sheets-Sheet l INVE R wmwiw ATTORNEY5 y 1934- J. 5. THOMPSON 1,959,117

GRATE CONSTRUCTION Filed Feb 25, 1930 5 Sheets-Sheet 2 INVEN R ATTORNEY y 15, 1934- J. s. THOMPSON GRATE' CONSTRUCTION Filed Feb. 25, 1930 a Sheets-Sheet 5 50w M Z1044;

I JFJ/ ISLVE ATTORNEYi' Patented May 15, 1934 UNITE STATES PATNT tie GRATE CONSTRUCTION of Maine Application February 25, 1930, Serial No. 431,282

5 Claims.

This invention relates to grate constructions of the type used in locomotives, marine boiler furnaces and the like. More specifically, the invention is concerned with a grate made up of bars and a supporting frame, this grate affording better and more efficient combustion of fuel by reason of the better distribution of air to the fuel bed obtained by novel features of the construction. The advantages of the new grate are not limited to any specific use but will be described in connection with the application of the new grate to a locomotive, merely for purposes of illustration.

With the increasingly heavy demands that have been made by railroads in the last few years on motive power, locomotives have increased in size and many additional appliances, such as feed water heaters, superheaters, etc. have been added. The efliciency of the boiler has been improved by this additional equipment, but the fundamental problem of burning the fuel has not received a proportionate amount of attention. As a consequence, while the utilization and conservation of the heat units generated by combustion have been placed on a more efficient basis, no improvements of considerable importance in the mechanism for burning the fuel have been developed.

The grates now used in locomotives are not sub stantially different from those which were in use many years ago, although minor changes have been made in the shape and form of the grate bars, the shaker mechanism, etc. In these grates, the usual construction includes a pair of side frames one on each side of the fire box secured against the side sheets and acentral frame extending along the median line of the fire box. The grate bars are provided with trunnions which are received in a pair of sockets, one in a side frame and one in the center frame, and the bars are thus arranged in two groups, all the bars in a group being connected to a common shaker rod so that they can be shaken in unison. Sometimes, and particularly in large locomotives, there are two center frames placed on opposite sides of the axis of the fire box, and the grate bars are then arranged in three groups.

The frame members are usually single castings of cast-iron and as they extend from end to end of the fire box, they are large and heavy. Ordinarily each frame member has a central web and top and bottom flanges of substantial width. The top of each frame member lies in contact with the fuel bed and forms part of the fuelsupporting surface of the grate. Since the frame top is solid, fuel that lies upon it cannot receive the amount of air necessaryfor good combustion and the tops of the several parts of the frame constitute dead surface on which the fuel burns sluggishly, with loss of fuel, formation of clinkers and the other ill effectswhich result from that type of combustion. The conditions in those parts of the fuel bed supported on the frame are frequently such as to be readily noticeable to the eye, since while the fuel may burn elsewhere with the emission of an intense glow, there are likely to be dull-colored bands lengthwise of the bed which indicate improper combustion in those parts of the fuel directly over the frame members.

That this condition is of serious consequence will be apparent from a consideration of the amount of grate area that is dead in a fire box of standard size. In what is known as alOO foot fire box, the dimensions are 12 long by 8 wide and a standard grate frame in such a box includes a pair of side members 3 wide at the top, and a pair of center members 4" wide at the top, a total frame width of 14" extending the length of the grate. The frame thus represents an area of approximately 15square feet which is dead area, or about 15% of the total area of the grate carries fuel which is not undergoing proper combustion because of insufficient air supply. The efficiency of the grate is thus reduced to an important extent due to the presence of the frame members, but while grates have continually been made in increasing sizes in the last few years, no successful attempts have been made, so far as I am aware, to correct the conditions above pointed out.

In order to overcome the above difiiculties which are inherent in grate constructions now in common use, I have devised a grate made up of a frame and grate bars in which practically all of the fuel, supported either on the bars or on the frame, receives a full supply of, air required for combustion and the air is distributed in such a Way that the fuel is burned completely and under most efiicient conditions. The airsupply is restricted in amount so that there is no substantial excess beyond that actually 3 needed but the air is distributed widely and to substantially all parts of the fuel, the dead space on the grate being reduced practically to the minimum necessary for proper support.

In the new grate, the bars have. openings therethrough for supplying air to the fuel bed and in addition the frame members are likewise provided with air passages so that fuel carried thereby receives air quite as effectively as if the fuel were supported on a bar. As a result, in the new grate there are no bands of sluggishly burning fuel such as occur on the ordinary grate, and there is no dead area in the fuelsupporting surface.

As another feature of my invention, I form the fuel-supporting surfaces of the frame mem bers upon replaceable elements which correspond quite closely in construction to certain parts of the grate bars. These replaceable elements are formed with a multiplicity of small fuel-supporting surfaces and are so constructed as to provide passages for the upward flow of air from the ash pan to all sides of the fuel which lies in contact with these small areas. By employing replaceable elements for the purpose, the weight of the main part of the frame is substantially reduced and the frame members may,

therefore, be installed in the fire box with much greater convenience and with much less labor than is now possible. After the members are placed in position, the fuel-supporting elements are mounted thereon and as these elements are the only parts of the frame which come in contact with the fuel bed and are subject to injury in use, their small size and replaceability makes maintenance of the grate a simple matter and if one element should become burned out, it is not necessary to scrap the entire frame.

For a better understanding of this invention, reference may be had to the accompanying drawings, in which Fig. 1 is a view in side elevation of a center frame member with a single fuel-supporting element in place;

Fig. 2 is a fragmentary plan view of a portion of a grate constructed in accordance with this invention;

Fig. 3 is a view in side elevation on an enlarged scale showing a frame member with a fuel-supporting element, in place;

Figure 3A is a view in side elevation similar to Fig. 3 but showing a modified construction.

Figs. 4, 5, and 6 are sectional views on the lines 44, 5--5, and 6-6 respectively of Fig. 3;

Fig. '7 is a plan view of a centre frame member illustrating grate bars mounted therein in section;

Fig. 8 is a view similar to Fig. 3 showing a modified form of the construction;

Fig. 9 is a sectional view on the line 9-9 of Fig. 8;

Figure 9A is a view similar to Figure 9 but showing a modification.

Fig. 10 is a plan view of the construction shown in Fig. 8;

Fig. 11 is a view in side elevation of a-modified form of the frame;

Fig. 12 is a sectional view on the line 12-12 of Fig. 11; and

Fig. 13.is a plan view of a side frame member similar to the centre frame member shown in Fig. 11.

Referring now to the drawings, the grate is illustrated in Fig. 2 as consisting of a plurality of bars mounted in two groups between a center frame member 21 and side frame members 22, only one of these side frame members being shown. The grate bars may be of standard construction'but I prefer to employ grate bars of the type shown in the co-pending application of Buckley, Serial No. 338,352,'filed February 8, 1929. The Buckley bar consists of a supporting member and a plurality of cross-bars mounted thereon, the supportingbar having trunnions at its ends which are received in sockets in the frame members so that the bars may be rocked in the ordinary manner. Grates of the Buckley type are illustrated in the drawings (Fig. 4), the carrier member 23 being shown as supporting a pair of cross-bars 24, the carrier member having trunnions 25 at its ends which are received in sockets 26 in the frame member. Each cross-bar is provided with a plurality of spaced lugs 27 on its opposite faces and at its upper end terminates in a plurality of small projections 28, the tops of which constitute the fuel-supporting surface. The projections are spaced apart to provide passages for the upward flow of air to the fuel supported on the tops of the projections. While grate bars of other constructions may be em- ,ployed in the new grate, I prefer the Buckley type by reason of the more efficient combustion which it affords.

The center frame member 29 in which the bars are mounted is supported at its ends only, the supports 30 being disposed at the ends of the fire box. The frame consists of a Web 31 with a bottom flange 32. Ordinarily a frame member of this type has a top flange similar to flange 32 and since the frame is a single casting extending from end to end of the fire box, it is usually made very heavy and the flanges may have a width of as much as 4". The top flange lies between the ends of the grate bars of the two groups and constitutes fuel-supporting surface. Since the flange is solid and no air can pass through it, the flange top is dead surface and fuel supported thereon burns sluggishly and is incompletely consumed.

In the new frame, the web 31 continues to the top and in a center frame member there are supporting lugs 33 at opposite sides of the web arranged in pairs midway between adjacent trunnion sockets. These supporting lugs carry removable fuel-supporting units 34 and each unit is preferably closely similar in construction to a cross-bar of the Buckley grate bar. Each supporting unit consists of a plate portion 35 on opposite faces of which are lugs 36 arranged spaced apart in a row. These lugs extend downwardly from the top of the plate and they define passages 3'7 between them for the upward flow of air. Each lug terminates at its upper end in a projection 39, the top of which is sub-divided by channels 40 to provide four small fuel-supporting surfaces 41. One such fuel-supporting element is mounted on each lug 33 so that between each pair of trunnion sockets there is a pair of elements, one on each side of the web of the frame. These elements are so formed that they project toward each other and lie over the top of the web 31 as shown more clearly in Figs. 5 and 6, certain lugs on each element being provided with spacing portions 42 and these portions on the two elements lying in contact and holding the elements properly spaced at the top. The frame member is provided with a strengthening rib 43 outlining each trunnion socket 26 and in order to hold the fuel-supporting units in position on the trunnion sockets.

In assembling the parts to produce the complete grate, the side and center frame members are installed in the ordinary manner. Thereafter the fuel-supporting units 34 are mounted on the lugs 33 on these members. Each unit is held against lateral displacement by the projections 44 on the ribs around the trunnion sockets, and the units of a pair on opposite sides of the center frame member are kept spaced at the top the proper distance by the spacing lugs 42. The grate bars are next placed in position in the frame in the ordinary manner and the end crossbars 24 of each grate bar lie spaced from the fuel-supporting units on the frame a sufficient distance so that shaking of the bars is not interfered with.

It will be apparent from a consideration of Fig. 4 that the top of each frame member is no longer made up of a flat solid piece of metal, such as the usual top flange. On the contrary the frame is provided with a fuel-supporting surface made up of a plurality of separate units which are readily replaceable. Each unit supports fuel on a multiplicity of small projections 28 and air for the combustion of the fuel may flow up through the passages 37 and be distributed through the lateral channels 40 so as to reach the fuel on all sides of each projection 28. As a consequence, the fuel supported on the frame members receives quite as much air as the fuel supported on the grate bars. Accordingly, the tops of the frame members no longer represent dead area and thus the effective area of the grate is increased by the total area of the tops of the frame members. As pointed out above, in a 100 ft. fire box, approximately only of the grate surface is live area in a grate of standard construction, while in the new grate substantially the entire surface is live and the efficiency of the grate is thus increased by 15%. At the same time, the life of the frame members is substantially increased and maintenance charges are lowered, since those parts of the frame which come in contact with the burning fuel are of small size and readily replaceable. Should the top flange of a grate frame member of ordinary construction become burned out, the entire frame member may have to be scrapped but in the present construction the top of the frame member lies at a substantial distance below the fuel bed and is protected by the fuel-supporting units. Should any one of these units become injured, it can be quickly replaced and only a small amount of metal has to be discarded.

In the construction shown in Fig. 3, the fuelsupporting element is shown at the left as terminating at one side of the trunnion socket, but if desired, the unit may have an extending portion 45 which projects out over the topof the trunnion socket (as shown in Figure 3A), these extensions on two adjacent units practically covering the socket so that the trunnion and socket are protected from the hot fuel.

In the construction shown in Fig. 8, the frame member is lightened between the trunnion sockets by being cut away as indicated at 46 and 47. There is thus a depression in the top of the frame member between adjacent trunnion sockets and projecting upwardly at the bottom of the depression is a lug 48 from which the lug 33 for the fuel-supporting unit projects. The construction shown in Fig. 8 is somewhat less costly to make than that shown in Fig. 3 by reason of the less amount of metal required for the frame member. Also, in the construction shown in Fig. 8, the fuel-supporting unit 34 is held in place by side lugs 49 formed on the end of the supporting lug 33.

The fuel-supporting units 34 illustrated in Figs. 3 and 8 are provided with fiat tops sub-divided by air channels into a multiplicity of small fuel-supporting surfaces. Since these fuel-supporting elements are stationary and do not move when the grate bars are rocked, it may be desirable to provide some means for causing ashes to slide off the tops of the fuel-supporting units toward the grate bars. For this purpose, a unit such as that designated 50 in Fig. 9A may-be provided. In this unit, the projections 39 at the top of the unit are of graduated height, those nearest the web 31 being of greatest height, so that the fuel-supporting surfaces at the top of the unit lie in a plane inclined downwardly and away from the central plane of the frame member. Ashes from fuel consumed on the unit have a tendency to fall into the channels 40 which define the fuel-supporting surfaces and to slide toward the grate bar lying adjacent the unit. When this grate bar is rocked, ashes pass to the pan in the usual way.

A somewhat heavier and more rugged construction is illustrated in Fig. 11. In this form, the web 31 has a flat top with the trunnion sockets 26 at the proper intervals. These sockets are outlined by supporting ribs 51, each rib having a downward extension 52 which terminates a substantial distance from the top of the flange. Between the trunnion sockets are the usual supporting lugs 33 and these lugs may be provided with lugs 49 to hold the fuel-supporting units in place, or similar lugs may be formed on the rib 52, if desired.

making the units in a form such that they can I be mounted on lugs similar in cross-section to the carrier members of the grate bars, it is possible to use the supporting units interchangeably with the cross-bars of the grate bars. This simplifies the manufacture and makes it necesa sary for the user to keep a stock of only a single kind of parts on hand. Of course, the fuel-supporting units of the type shown in Fig. 8 are not interchangeable with cross-bars by reason of having the end extensions.

It will be seen that in the new grate, practically all cross-sectional area of the fire box is useful combustion surface. Not only is air supplied to fuel carried on the grate bars, but there is a fuel supply to those parts of the grate where fuel is carried on members of the grate frame. There is an air supply, therefore, to those parts of the fuel bed which lie beyond the ends of the grate bars along sides of the fire box, and also down the middle of the fire box. Consequently, the entire fuel bed burns with a supply of air which insures that the fuel will be consumed to a fine ash and without formation of clinkers.

By lightening the web of the main casting of the frame members, there is less likelihood of 1- damage to these members both during shipment and installation and the installation is less laborious and can be performed much more rapidly ffo its

i 'io than is possible with the present form of frames.

After the main castings of the frame are in position, the fuel-supporting elements may be mounted thereon rapidly and with no difficulty and thereafter the grate bars may be placed in position in the ordinary way.

I claim:

1. In a grate, a grate frame having spaced trunnion sockets along its top, lugs on at least one face of the frame, said lugs lying only in the spaces between the sockets and below the level of the sockets, and a fuel supporting unit mounted to straddle each lug, each unit having fuel supporting surfaces lying above the top of said frame.

2. In a grate, a grate frame having spaced trunnion sockets along its top, supporting means on at least one lateral face of the frame, said means lying only in the spaces between the sockets and below the top of the frame, a removable unit mounted on each supporting means and providing fuel-supporting surfaces lying above the level of the top of the frame, and means for maintaining said units against accidental displacement.

3. In a grate, a frame comprising a web having trunnion sockets therein in a row along its top, a row of lugs projecting laterally from one face of the web, said lugs lying only in the spaces between said sockets and below the top of said web, and a fuel-supporting unit on each lug, each unit extending from substantially one edge of one socket to the adjacent edge of the next socket.

4. A grate comprising a frame member including a web having trunnion sockets therein and a plurality of lugs, each lug lying between a pair of sockets and projecting outwardly from one lateral face of the web below the top thereof, grate bars each having a pair of trunnions, one of which is received in one of said sockets, said grate bars including fuel-supporting bars lying parallel to the plane of the frame and between the trunnions of said grate bar, the end fuelsupporting bar on each grate bar lying spaced from the frame, and a fuel-supporting unit on each lug and lying in the space between said end fuel-supporting bar and said web.

5. A grate construction comprising a frame having spaced trunnion sockets, lugs extending from the sides of the frame below the top thereof between the trunnion sockets, fuel-supporting units each including a plurality of small upwardly extending fuel-supporting projections separated by air channels and having a cut-out por tion of a contour similar to the lugs on the frame but slightly larger than said lugs and surrounding the lugs to support the unit thereon but to allow it to move to a limited extend relative thereto.

JAMES S. THOMPSON.

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