US3508535A - Grate - Google Patents

Description

April 28, 1970 J, J, MAR-HN ET AL 3,508,535

@RATE 'Filed May 2 8, 1968 l |||I U5 .hh

United States Patent O 3,508,535 CRATE Johannes Josef Martin :and Walter Josef Martin, both of Leopoldstrasse 248, Munich 23, Germany Filed May 28, 1968, Ser. No. 732,700 Claims priority, application Germany, June 2, 1967, 1,551,872 Int. Cl. F23h 23/ 02 U.S. Cl. 126-163 6 Claims ABSTRACT OF THE DISCLOSURE A gate for supporting combustible materials in furnaces includes a plurality of grate bars each of which has a straight main bar portion formed with cooling channels for cooling uid, and protuberant portions projecting from the main bar portion. The protuberant portions are provided with internal compartments communicating with at least some of the cooling channels in the associated main bar portion so as to provide for cooling off the protuberant portions to protect the same against adverse effects of elevated temperatures.

BACKGROUND OF THE INVENTION The present invention relates to grates, and more specifically to grates of the type used in furnaces and similar installations.

The material-supporting grates in furnaces serve to hold theI material to be combusted in predetermined position. They generally consist of a plurality of grate bars and these latter are usually cooled by providing them with cooling channels through which cooling fluid is circulated. This is done to protect the grate bars as much as possible against the adverse influences of the elevated temperatures to which they are subjected during combustion of the combustible material. If this is not done, the life of these grate bars is significantly reduced.

Frequently, adjacent grate bars of grates of the type here in question are arranged to perform relative movements, for instance reciprocatory movements relative to one another, so as to stir the bed of combusting material and/ or break up this bed or individual components thereof, such as lumps of slag and the like. To make this stirring and breaking up more effective, the grate bars are usually provided with protuberant portions which project to one side of the respective grate bars, usually in opposite direction above the general plane of the grate. This is shown for example in German Patents 959,212 and 969,643.

The provision of these protuberant projections has been found highly advantageous because they not only serve to stir up the bed of combusting material, loosening the individual components of the bed and thus providing for increase circulation of necessary combustion air therethrough, but also because they serve to break up such individual components as lumps of slag, as pointed out above, and thus serve to accelerate combustion of the thereby obtained smaller pieces. However, in constructions of this type it has been found that the protuberant projections, which are not protected against the adverse influences of elevated temperatures as are the main portions of the respective grate bars, are destroyed much more quickly than the latter under the very intense heat developing in installations of the type here in question. This problem is aggravated by the fact that in many such installations a variety of combustible materials are to be burned, with different materials having different heating values. A particularly bothersome problem is the combusting of materials which have intermixed therewith various of the highly-combustible synthetic plastics be- 3,508,535 Patented Apr. 28, 197() cause this leads to locally very intense heating which has been found to be very damaging to the protuberant projections, particularly their upper edge portions. In conjunction with the fact that these protuberant projections are in any case subjected to rather high mechanical stresses this frequently results in a drastic reduction in the lifetime of the protuberant projections. In this context it is pointed out that it is an important feature for the protuberant projections to have relatively sharp edges which factor assists in the crushing of materials to smaller pieces, and these sharp edges are destroyed particularly under these circumstances just outlined. Added to this is the fact that significant local overheating in the protuberant projections may result in the development of internal stresses and the formation of cracks.

It is therefore a general object of the present invention to overcome these various disadvantages outlined above.

A more particular object of the invention is to provide an improved grate of the type under discussion which eliminates the above-mentioned disadvantages but it does so in a simple and inexpensive but yet highly advantageous manner.

A concomitant object of the invention is to provide a grate of the type in question which does not require the provision of additional cooling means for obtaining the purposes outlined above.

Yet a .further object of the invention is to provide such `a grate which may be utilized with equal advantage in many types of installations where materials are to be combusted, for example in various types of industrial furnaces including batch-type furnaces, continuous-type furnaces and others.

SUMMARY OF THE INVENTION In pursuance of the above-outlined objects, and others which will become apparent hereafter, one feature of my invention recites in providing a grate of the type here under discussion which comprises a plurality of grate bars serving a main bar portion formed with cooling channels for the passage of the cooling fluid therethrough, and protuberant portions projecting from the main bar portions. In accordance with the invention the protuberant portions are provided with respective internal compartments which communicate with at least some of the cooling channels of the associated main bar portion so as to provide access of the cooling fluid from such cooling channels to the internal compartments. By this means I obtain cooling of the protuberant portions and protect the latter against the adverse effects of elevated temperatures without necessitating the provision of additional cooling means and without significantly increasing the technological and economic expenditures required in constructing and maintaining grates of the type here under discussion.

In this manner the protuberant projections are subjected to effective direct cooling so that the material of which they consist is subjected to internal cooling, resulting in an increase of its ability to withstand mechanical stresses and in a consequent increase of its lifetime.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammatic side-elevational fragmentary view of two grate bars embodying the invention;

FIG. 2 is a section, on an enlarged scale, taken on the line II-II of FIG. 1; and

FIG. 3 is a vertical fragmentary section through a grate bar incorporating a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, and firstly FIGS. l and 2 thereof, it will be seen that in FIG. 1 we have illustrated the end portions of two grate bars 1 of the type here under discussion. It will be appreciated that such grate bars are elongated, that is in FIG. 1 in the direction towards the left-hand side of the drawing, and that each grate comprises a plurality these grate bars which in the embodiment of FIG. 1 are arranged in two superimposed layers, each of which is diagrammatically represented by the respectively lower and the respectively upper grate bar 1 in FIG. 1. This, however, is of no direct importance for the present invention except that it should be remembered that in an embodiment of this type the grate bars of the upper and lower layers may be arranged reciprocally with reference to one another.

In the embodiment of FIGS. 1 and 2 the grate bars each comprise a main bar portion 1 and protuberant portions 2. Although only one of these portions 2 is shown in FIG. 1 for each of the grate bars it will be understood that there may be two associated with each grate bar, namely one located at each opposite end of the grate bar, or that there may be more than two. In the illustrated embodiment the protuberant portions 2 are located in the region of the illustrated ends of the grate bars, rearwardly of the respective end faces 5.

lFIG. 2, which is a section taken on the line II-II of FIG. 1 but on an enlarged scale, shows that the grate bars are provided with a plurality of cooling channels 3 extending in longitudinal direction. These cooling channels 3 in the illustrated embodiment are bounded by the respective outermost wall portions 1a of the grate bar, and the space between the wall portions 1a is further subdivided by wall portions 1b so as to provide a plurality of the longitudinally extending cooling channels 3. It will be notified that these extend from what in the drawing will be seen to be the lower surface of each grate bar in the direction towards the upper surface, from which the protuberant portions 2 extend, but that they terminate short of this upper surface. This is clearly shown in FIG. 2. While in FIGS. 1 and 2 the cooling channels 3 are seen to be open at the lower surface of the grate bars, it will be appreciated that they may also be closed by a suitable closure means, such as an elongated strip or plateshaped member which is illustrated in FIG. 3 and which will be further discussed in the discussion of the embodiment illustrated in that figure.

In accordance with the present invention the protuberant projections 2, of which only one is visible in FIG. 2, are provided with internal compartments 4 which are illustrated in broken lines in FIG. 2 and which communicate with respective ones of the elongated cooling channels 3. Thus, cooling fiuid which circulates through the cooling channels 3 will also enter into these internal compartments 4 and will thereby cool the protuberant projections 2 with the highly advantageous results outlined above.

It is of Course possible to have all of the cooling channels 3 communicate with the one or several internal compartments in each of the respective protuberant projections 2. In the illustrated embodiment, however, only some of the cooling channels 3 are in such communication. The others, in FIG. 2 the respectively laterally outermost ones, are not so in communication. However, in the region of the grate bar beneath the respective protuberant projection 2 the cooling channels which are not in communication with the internal compartment or compartments in the protuberant projections 2, extend at least closer to the upper surface of the grate bars 1. This is indicated in broken lines in FIG. 2 where it will be seen that in the region below the protuberant projections 2 the laterally outermost ones of the cooling channels 3 are upwardly extended so as to provide hollow upper extensions 3a. The reason for showing these extensions 3a in dash lines in FIG. 2 will be appreciated when the section line II--II in FIG. 1 is considered.

In view of these extensions 3a heat exchange is also improved in the region of the laterally outermost cooling channels 3. Evidently, the extensions 3a could be eliminated and replaced with internal compartments 4 if desired.

Coming, finally, to the embodiment shown in FIG. 3 it will be seen that it is illustrated herein a vertical longitudinal section through an end portion of a grate bar of the type shown in FIG. l. The main bar portion is identified with this embodiment with reference numeral 1', the protuberant projection with reference numeral 2 and its end face with reference numeral 5. The partition walls 1a and 1b respectively correspond to those identified with reference numerals 1a and 1b in FIG. 2. Reference numeral 3 in FIG. 3 identies one of the cooling channels 3. Unlike the embodiment in FIG. 2, the embodiment illustrated in FIG. 3 does not have downwardly open cooling channels 3. Rather, an elongated closure means in form of a strip, plate or similar element, is identified with reference numeral 6 and closes the downwardly open cooling channels 3 in the manner illustrated in FIG. 3. The internal compartment or compartments in the protuberant projection 2 are identified with reference numeral 4 in FIG. 3. In accordance with the embodiment herein illustrated, the compartment 4' is elongated in longitudinal direction of the protuberant projection 2 so as to comprise a portion 4 extending towards but short of the face 5 of the grate bar. This serves to provide still more intensive cooling, particularly also in the region of the face 5', and thus protects the grate bars still better.

A further difference of the embodiment in FIG. 3 over that shown in FIGS. 1 and 2 is the fact that the cover or closure means 6 is provided Iwith guide or deliecting means which serves to'guide or deflect the stream of coolant fluid into the compartment 4', 4". In the illustrated embodiment this means is an upwardly projecting section 7 of the cover means 6 which projects upwardly into the compartment 4', 4" and thus serves to deflect the stream of coolant uid, whose path is shown in dashed line and identified with reference designation y, upwardly into the compartment 4', 4 in the manner shown in FIG. 3. By resort to this measure, we obtain a further improvement in the intensity of cooling of the protuberant projection 2', particularly in the region of the upper end of the projection 2'.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a grate which is particularly suitable for use in furnaces and similar installations, it is not intended to be limited to the details shown, since various modification and structural changes may be made without departing in any way from the spirit of the present inventlon.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a grate of the type used in furnaces and similar installations for supporting materials to be combusted, a plurality of elongated grate bars having a main bar portion formed with a plurality of longitudinally extending transversely spaced cooling channels for passage of a cooling fluid therethrough, and protuberant portions projecting from said main bar portions; and internal compartments provided in the respective protuberant portions and communicating with at least some of said cooling channels of the associated main bar portions for enabling access of the cooling fluid from said plurality of cooling channels to said internal compartments to thereby effect intensive cooling of said protuberant portions and protection of the latter against adverse effects of elevated temperatures.

2. In a grate as defined in claim 1 wherein said grate bars have respective opposite ends each having an end face, said protuberant portions being provided in the region of said ends inwardly of the respective end faces, and wherein said internal compartments extend in said protuberant portions in longitudinal direction of said grate bars and towards the respectively associated end face.

3. In a grate as defined in claim 1, each of said grate bars having a first surface from which the respective protuberant portions project and an opposite second surface, and each of said grate bars being provided with said plurality of said cooling channels extending inwardly from said opposite second surface to within a predetermined distance of said first surface beneath the respective protuberant portions; and wherein some of said cooling channels communicate with said internal compartments and the remaining ones of said cooling channels compose sections extending to within a smaller distance of said first surface than said predetermined distance in the region beneath the respective protuberant portions.

4. In a grate as defined in claim 1, said grate bars each having a first surface from 'which said protuberant projections extend and an opposite second surface, said cooling channels being provided in said second surface and extending longitudinally of the respective grate bar as well as inwardly of said second surface toward said first surface, and wherein said cooling channels are open at said second surface.

5. In a grate as defined in claim 1, said grate bars each having a first surface from which said protuberant projections extend and an opposite second surface, said cooling channels being provided in said second surface and extending longitudinally of the respective grate bar as well as inwardly of said second surface toward said first surface, said cooling channels being open at said second surface; and further comprising cover means clos ing said cooling channels at said second surface.

6. In a grate as defined in claim 3, said cooling channels being open at said opposite second surface; and further comprising cover means closing said cooling chan nels at said second surface and including guide portions operative for defiecting cooling fiuid into said internal compartments from the respective cooling channels communicating with the same.

References Cited UNITED STATES PATENTS 1,646,700 10/ 1927 Mellor 126-163 1,664,903 4/ 1928 Skelly 110-74 X 2,197,428 4/ 1940 Erb 1l0-74 X 2,745,364 5/ 1956 Martin 110-74 CHARLES I. MYHRE, Primary Examiner U.S. Cl. X.R. -74

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