US2072512A - Furnace grate - Google Patents

Description

A. G. WHELER FURNACE GRATE March 2, 1937.

Filed Nov. 29, 1935 M ATTORA 'Ex-5.

Patented Mar. 2, 1937 UTE T? ATENT OFFICE 2 Claims.

This invention relates to grates for furnaces and has for its object a grate bar, the body of which is provided with upper and lower rows or sets of transverse bars arranged in different hori- 5 Zontal planes with their ends located in different radii from the axis of the grate bar but with their ends substantially the same radial distance from the axis of the grate bar, so that when the grate bars of one set or pair of bars provided with the upper and lowers rows are rocked to shake the` fire to remove ashes, the ends of like sets of adjacent grate bars come together while the ends of the other set of cross bars separate, thus preventing the ashes and coals from running in a stream into the ash-pit, particularly when relatively ne coal, as buckwheat, rice, etc. coal is used, and further has for its object an adapter for applying to standard rocking grates, as triangular grate bars, a4 second set of cross bars arranged in the manner just set forth for the purpose of preventing running of the ashes and hot coals through the grate during the shaking of the fire.

In most instances, furnace grates are designed for use with coarse grades of coal, and accordingly, it is necessary to carry a thick layer of ashes on the grates when burning buckwheat coal with a blower. However, the grates have to be shaken to eliminate the ashes formed each day and it becomes quite a problem to shake out some of the ashes and not start what is known as a buckwheat run due to the fact that there is no support between the grate bars, when the grate bars are rocked. The grate bars have to be separated when they are in a level position so that they will not bind when they are rotated. Thus, a space occurs the full length of the grate varying from of an inch to even one inch in coarse grates. When burning fine coal, as buckwheat,

4o rice, etc., the grate bars do not properly coact and the hot coals frequently run through to the ashpit between the grate bars.

Again, grates are shaken in pairs, usually, when one pair is shaken, the other two remain level, but

the ash bed is disturbed and a large opening occurs at the junction of the rotating grate with the stationary grate, so that runs occur very easily.

Also, on account of the heavy ash bed necessary when burning fine coal, as buckwheat coal, on coarse grates, the eiiiciency of the draft or blower is cut down, as it is hard to maintain the correct amount of air due to the operators not knowing just how thick the ash bed is. If not enough air isv used, not enough heat is produced.

If too much air is used, gas is forced out through the feed door.

The general object of this invention is a grate construction and also an attachment of simple construction which can be quickly and conveniently attached and adjusted to the standard set of grates and which will permit the use of line coal. That is, the attachment, when applied to the standard grate, converts the grate for fine coal use with the same efficiency as was formerly obtained by using coarser grades of coal with the original grate. It closes up the space between the original grates because it is attached approximately on a line with the center of rotation of the grates. The attachment bars can actually touch each other, because as the grates are rotated, the attachment bars are retreating from the farthest point of rotation instead of advancing as do the teeth of the original grates. A very thorough sifting of the ash bed takes placeY when the grates are rotated back and forth, but since there are not attachment bars on the upper face of the grate, when two adjacent upper faces are turned towards each other, the full capacity of the original grate for dumping the lire is maintained. This is important as clinkers can be discharged easily but the instant the grates are brought back to the original level position, a perfect support for the fuel bed is again maintained. Thus runs are impossible, a thorough and quick cleaning of the fire is easily obtained, the re can be shaken till a red glow occurs in the ash-pit and therefore the operator knows exactly what the resistance of the fuel bed is so he can act and maintain his blower to work at full eiciency. As a matter of fact, so efficient are these attachment grate bars that many people can burn buckwheat coal without a blower, but where this is impossible, due to the draft conditions, the blower runs for very much shorter periods and a fewer number of times per day. Formation of clinkers is materially reduced as clinkers are formed dur ing a long continuous running of the blower. Eeveryone is familiar with the phenomenon of how easily heat is produced by a fresh re. By means of these attachment grate bars, the fire is thoroughly cleaned without waste and the eiiciency of a fresh fire is more nearly approached. Also, due to the combination of the radially extending projections on the original grate and the projections on the attachment bars, a considerable rocking of the grates back and forth is permitted without opening a large space between the grates. This allows the fine ashes to fall through but prohibits the coal from dropping. Also, in old grates, the gears become worn, so that the grates may not be level, when at rest, although the operator may think they are level, due to the position of the shaker handle. This out-of-level condition is the cause of many runs. With my attachment bars, the fuel bed is still supported under these conditions so no runs occur.

While my bars are detachably secured to the side of the original grate, it is not outside the nature of this invention to form or cast the attachment integral with the grate bar or to Weld these bars to the original grate, after they have been adjusted to the correct position. Some people prefer to have them welded and it has been my practice to do so on request.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawing in which like characters designate corresponding parts in all the views.

Figure 1 is a fragmentary plan view of the grate ring of the furnace showing two of the revolvable grate bars in operated position.

Figure 2 is an enlarged view taken on line 2 2, Figure 1, showing the normal position of the grate bars.

Figure 3 is a view similar to Figure 2 showing the position of two of the bars, which are coupled together, when rocked in a normal shaking" operation.

Figure 4 is a plan view of one of the adapter plates.

Figure 5 is a sectional view on line 5-5, Figure 4.

'I'he invention comprises, generally, a grate bar of the rocking type including a body movable about a lengthwise axis and having upper and lower sets of cross bars or cross bars arranged in different horizontal planes and with their ends located in different radii but substantially the same radial distance from the axis of the body. The projections of one set, that is, one set of cross bars, as the lower set, being spaced apart a less distance than the other set, and also partly obstructing or closing the interstices between the cross bars of the other set. Thus, each grate bar is provided with upper and lower rows of coarse and fine teeth or projections along the edges and coacting with the row of adjacent bars. Normally, the ends of like sets of adjacent bars stand close together and the ends of the other sets or rows of adjacent bars are separated. Hence, when oscillating the bars in reverse directions, like sets or rows of projections of adjacent bars open or separate or recede from each other while the other sets are closing toward each other. Hence, during shaking, a thin bottom layer only is cut 01T from the body of fuel in the fire pot and at no time is the fuel free to run through the grate during a gentle rocking of the grate bars.

I have here shown my invention as embodied in the conventional type of furnace grate, which includes a grate ring I mounted in the fire pot, and sets of grate bars 2, 3, rotatably mounted in the grate ring, there being usually two grate bars in each set, each being rotatable about an axis reversely relative to the other, one of the grate bars having an end 4 of its axle shaped to receive a crank or shaker. The grate bars are connected together so that they rotate in reverse directions b y suitable gearing 5.

In the ordinary furnaces, there are usually two sets of grate bars 2, 3, operable or shakeable, one grate bar of each set being formed to receive the shaker or crank. Each grate bar comprises a suitable body here shown as in the form of a shaft, and cross bars 6 extending transversely of the shaft and spaced apart for permitting air circulation, and also sifting of ashes into the ashpit and the passage of ashes into the ash-pit when the grate bars are oscillated or rocked. Each grate bar also includes a second set or row of transverse bars 'I arranged in a different horizontal plane or in a different radius from the shaft than the upper cross bars 6 but with the ends Ia of the bars 'I located substantially the same distance from the axis of the shaft or body of the grate bar, as the ends of the cross bars 6.

In the illustrated embodiment of my invention, the cross bars 'I are provided with a base strip 8 secured to the end portions of the cross bars 6 and underlying the same, and the base strip 8 is formed with openings 9 of less width than the interstices between the cross bars 6. The cross bars I are also spaced apart a less distance than the cross bars 6. The cross bars 'I are, in the illustrated embodiment of my invention, shown as applied to a standard triangular grate, and the base strip 8 with the cross bars is an adapter for providing a standard grate with additional rows of cross bars located relatively to the regular cross bars 6, as hereinbefore described. The adapter or base strip may be applied and secured to the grate bar by welding or by mechanically fastening the same to the cross bars 6.

As here shown, the base strip 8 is secured to the end portions of the cross bars 6 by means of clamping members extending through some of the slots or perforations therein between the bars 5 and through a spanning member or washer I0, these fastening members being bolts I I. As the cross bars taper toward their ends, any clamping force would cause them to move oi the ends of the cross bars 6 and hence additional fastening members are provided for holding them from such movement.

I2 designates the additional fastening members which are here shown as bolts having their headed ends formed hook-shaped at I3, the bolts extending through slots in the base strip 8 and transversely between the transverse bars fia to the opposite side thereof where they are secured by means of a nut I4 threading against a washer I5 spanning the space between two adjacent bars 6a.

In applying the adapter to a standard triangular grate bar, the adapters are preferably applied only to the opposite ends of the transverse bars 6 instead of to the ends of all three transverse bars 6, Ba, and in shaking the grate, the grate bars are rocked only through a small angle, say of not greater than and are initially rocked from starting or normal position to cause the rows of two adjacent bars 'I to move away from each other and the ends of the rows 6 to move toward each other, as seen in Figures 2 and 3. To dump the re, the grate may be rocked through a greater angle.

In operation, the set of grate bars normally stand, as shown in Figure 2, in which the ends of the cross bars 'I of two adjacent grates confront each other, and thus prevent fine coal from running or sifting down through the grate bars. Also, the base strip 8 owing to the restricted opening 9 prevents such sifting or running. When it is desired to shake ashes from the fire, the grate bars are oscillated into the position shown in Figure 3 back to the position shown in Figure 2 over a period of time sucient to remove excess ashes or until a faint glow appears in the ash-pit. Thus, when the grate bars are rocked into the position shown in Figure 3, the ends of the transverse bars 6 are close together and prevent running of the hot coals into the ash-pit. Hence, at any time during the ordinary shaking of the grate is there any large passage through which the coals can run.

By my invention, a grate is provided for ne coal, as buckwheat and rice coal, through which it is impossible for the coal to run, and further, by my invention, an ordinary grate intended for coarse coal may be readily adapted for ne coal, as buckwheat or rice coal.

1. In a grate bar of the rocking type including a body movable about a lengthwise axis and having cross bars spaced apart, the combination of a strip secured to the end portions of the cross bars and extending lengthwise of the body, the strip being formed with cross bars arranged in a different radius from the former cross bars and the ends of which are substantially the same radial distance from the axis of the body as the ends of the former cross bars, the strip being formed with perforations therethrough registering with and of less width than the interstices between the former cross bars and the cross bars of the strip being spaced apart a less distance than the former cross bars.

2. In a grate construction, a. grate bar comprising a body mounted to oscillate about a horizontal axis, and transverse cross bars spaced apart and having their ends located on opposite sides of the body normally in substantially the same plane and above the axis of the body, the ends of the cross bars forming upper rows of grate teeth opposed to the corresponding rows of the adjacent grate bars, the body also having a second row of teeth located below each of the first rows and spaced apart a less distance than the transverse bars of the rst row, the lower rows of teeth being normally arranged in substantially the horizontal plane of the axis of the grate bar and located to be normally spaced apart a less distance from the ends of the corresponding lower row of teeth of the adjacent grate bars when the grate bars are in normal position, when the upper rows of teeth of each grate bar are spaced apart from the corresponding teeth of the adjacent grate bars, the grate bars being movable about their axes to separate the lower rows of teeth of adjacent grate bars and bring together the ends of the upper rows of teeth of the adjacent grate bars.

ARTHUR GORDON WHELER.

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