US2418732A - Grate with water cooled bars - Google Patents

Description

April 8, 1947. E slNGY 2,418,732

GRATE WITH WATER CQQLED BARS Fi led May 19, 1945 5 Shets-Sheet 1 April 8, 1947. slNGY J 2,418,732

GRATE WITH WATER COOLED BARS Filed May 19, 1945 3 Sheets-Sheet 2 I'd- I, /7

l /c' l I K I April 8, 1947. E. SINGY GRATE WITH WATER COOLED BARS a SheetsSheet s Filed May 19, 1945 Patented Apr. 8, 1947 GBATE WITH WATER CQGLED BARS Ernest Singy, Geneva, Switzerland, assignor to Ygnis S. A acorporation of Switzerland Application May 19, 1945, Serial'NO. 594,665" In Switzerland May 31, 1944 10 Claims.

The furnaces of-high pressure steam boilers are generally equipped with horizontal grates supported at their lateral edges by the cylindrical wall of the furnace. These furnaces have never theless certain objections. As a matter of fact, with a horizontal grate, the fireman must continually distribute the fuel-by degrees as it is discharged-on the whole surface of the grate, in such a manner that the fuel layer has approximately the same thickness on the whole grate surface. Further, in order to remove the clinkers, the fireman must disturb the whole fire bed. These facts make the. maintenance of the fire difiioult and laborious.

The present invention has for its object a grate with water cooled bars, tending to eliminate the above described inconveninces, by the fact that the grate is made of a double row of steps consisting of superposed hollow bars, formed in the shape of a U, the two lateral branches of which have a, spread varying progressively from the top bar to the bottom bar and with a hollow element above said top bar, said hollow element closing the upper end of the internal space of the grate comprised between the branches of the bars, and by the fact that passages are provided for the air required for the combustion, said passages connecting the internal space of the grate with the external space, with .the result that the surface of a grate made up of said stepsis much larger than that embraced by the lower U shaped bar and which corresponds to the surface of anordinary horizontal gratefor the same furnace. v

The annexed drawings showschematically and by way of examples, two forms. of embodiment of the grate.

The Figures 1 to 4 show a first form of embdi ment of the grate placed in a horizontal high pressure steam boiler.

Fig, 1 isa view in profile of the grate, a portion of the wall of the boiler being removed.

Fig. 2 is a general View of the combustion chamber of a horizontal boiler equipped with the grate represented in Fig. 1.

Fig. 3' is a view taken from the front of the grate, the front wall of the boiler being removed.

Fig. 4 is a plan view of the top of the grate.

Fig. 5 is a front view of a second form of embodiment of the grate with portions shown in section.

Figs. Etc 8 show a third form of embodiment of the grate mounted in a fore furnace.

Fig. 6 is a View of thecross section of the fore furnace and of the. grate, made along theline VIVI of the Fig. '7.

Fig. 7 is a view of a partial cross section of the fore furnace made along the line VII-VII of the Fig. 6.

Fig. 8 is a view of the cross section of the fore furnacemade along the line VIII-VIII of the Fig. 7.

Figure 8a is a vertical cross sectional view similar to Figure 8 but illustrating a modified form of individual grate bars.

Similar reference characters designate corresponding parts throughout the several views.

In the form ofembodiment represented. in Figures 1 to l, the grate consists of hollow bars is, lb, '0, formed in the shape of a U. These bars are superposed one above the other and the spread between their lateral branches grows from the top bar to the bottom bar. Above the top bar, there is a hollow element 2. The dififerent bars as well as saidelement are connected to a system of water circulation by ducts 3 and i and by means of a hollow. wall 5 to which said bars and said element are fixed, and which terminates the grate at one end; The length of the lateral branches of the U shaped bars grows also from the top bar to the bottom bar so that the grate presents steps on the entire length of the bars.

Air passages 6' are provided between the bars and connect the internal space [2 of the grate, which is located between and below the lateral branches of the bars, to the external space.

The Spread between the lateral branches of thelower'bar lo is chosen such that the outer edges of-its branches come in contact with the lateral walls? of the chamber of combustion assumed to 35..be of circular cross section at the highth of supfurnace so that the lower bar rests on the lateral walls of the combustion chamber, it is but necessary to close the passages remaining free between the-end walliand the lateral walls of the cylindricai chamber-by means of'a Wall 9,- this operation resulting in the formation of a space Ill constituting the fire box and a space H constituting the gas combustion chamber in which the combustion of the gases escaping from the fuel can take place. The hollow wall t is supported by-a dam- 24 separating the internal space It of the grate from the gas combustion chamber H. A filling l3 shuts the gap between the front end of the lower bar and the front wall of the boiler so as to complete the separation of the fire box it] from the space 12. It may be seen easily that the latter space 12 is entirely separated from the gas combustion chamber II and that itmay be used for the feeding and pre-heatingof the air necessary for the combustion. To this effect, a duct (4 connects said space [2 to a source of compressed air not represented. As shown in the drawing (Fig. 3), the air passages 6 consist of slots left between the bars, the cross section of said bars having the general shape of a half circular crescent, with the exception of the bottom bar which forms simultaneously the base of the fire box, the outer lateral edges of said bottom bar being shaped so as to rest on the lateral walls of the boiler. The top element has a crescent shaped cross section. The hollow wall 5 is topped by a hollow wall [-5 acting as a bailie for the combustible gases; the said hollow wall 15 extending from the wall 5 to the duct 3. In certain cases, the wall l5 may consist of a solid cast iron wall or be made up of fire resisting material.

From Figs. 1 to 4 it may be deduced that, owing to the double series of steps afforded by the U- shaped bars of the new grate, the upkeep of the fire bed is greatly facilitated as compared with that of a fire bed on a horizontal grate of the regular type. Indeed, the new grate has a cross section in the general shape of a triangle with horizontal base and its top located in the vertical median plane of the boiler, that is lined up with the fire door H. The fuel thrown in the fire box by the fireman distributes itself so to speak automatically on both sides of the grate, running down the steps. When the fire box is completely loaded, the fuel forms two piles I 8 the outer surfaces of which run down from the point above the top bar of the grate towards the lateral walls of the cylindrical space. The fuel layer is therefore thinner at the level of the upper steps of the grate than at the level of the lower steps. Furthermore, the air passages 6 are inclined in such a way as to force the air to penetrate downwards in the interior of the mass of the fuel I8 with the result that the new grate allows a good gasification and a complete combustion of the gases produced, this being due to the fact that the air introduced through the upper air passages must traverse but a thin layer of fuel. On the contrary, in the lower portion of the fuel pile l3, where the layer of fuel is much thicker, the temperature can reach values sufiicient to cause the gasification of the fuel.

Further, the ignited gases escaping from the piles 18 run along the lateral walls of the fire box instead of remaining in the central portion of the furnace as is the case in the boilers equipped with a horizontal grate of the usual type. This is due to the fact that the air necessary for the combustion introduced into the pile I8 is directed toward the lateral walls of the fire box and to the fact that the wall l5 makes it impossible for the gases to travel directly from the fire box lihto the gas combustion chamber I I. Said wall 15 forces the gases to follow the lateral walls of the fire box and of the gas combustion chamber. It follows that the emciency of a boiler equipped with a grate such as the one described above is higher than that of a boiler equipped with an ordinary horizontal grate.

Lastly, the quantity of fuel accumulated in the fire box being larger, and the air necessary for the combustion being pro-heated in the space l2 and in the air passages 6, the combustion takes place in a more uniform manner.

The upkeep of the fire bed is also facilitated, because the distribution of the fuel takes place almost automatically and because on the other hand, the clinkers cannot adhere to the grate which is water cooled, with the result that the clinkers can be removed from one or the other half (right hand or left hand side of the fire box) without disturbing the other half.

It is evident that the above described grate may be made to suit the various types of high pressure steam boilers of horizontal design such as the single or double boiler type, or the tubular, semi-tubular or multi-tubular type or those of vertical design with single boiler or of the tubular, or Field type.

In the case of vertical boilers, the U-shaped grate bars are fastened and connected directly to that part of the boiler wall facing the fire door, and the wall 15, being of no use here, is suppressed.

The grate bars may also have a cross section of a shape different from that represented by the Fig. 4, the desirable shape being partly determined by the conditions of functioning of the boiler which is to be equipped on one hand, and on the other hand by the requirements imposed as regards to the upkeep of the grate bars.

For instance, tubular grate bars of circular cross section may be adopted (Fig. 5), joined together on their entire length by means of intermediate strips 8 acting as bafiles and forcing the air through the air passages 6 traversing the bars from one side to the other, although in this form of embodiment, the scraping and cleaning of such bars is not so easy. On the other hand, it becomes possible to arrange the air passages 6' in a more judicious manner than in the first form of embodiment described.

The grate, object of the present invention, may also be adapted to provide a so-called "fore furnace, that is a, fire box which would extend, partly or entirely, out of the general outline of the boiler B and in front of same (Figs. 6 to 8). In this latter form of embodiment, the grate bars are fixed and connected directly to the wall W of the fore furnace, opposite to the fire door H, said wall being topped by the flue 22.

The hopper [9, containing the provision of fuel, is then located just above the fire box and is provided with a channel 20 leading just above the grate and on the axis thereof.

The top element 2 may have for its cross section, either the general cross sectional shape of a triangle (see Fig. 8), or the cross sectional shape of a crescent as per 22. in Fig. 8a. The definite shape of said element is chosen in such a manner as to separate in two approximately equal parts the fuel arriving through the channel 20. A wall 2| forming a baffle for the ignited gases is provided in order to compel said gases to run along the walls of the fore furnace which are hollow and connected to a water circulating system.

From the above, it may be seen that the described grate, object of the present invention, is especially adaptable for equipping combustion chambers or furnaces of cylindrical form, that its use permits a substantial economy of fuel and results in asimple and easy upkeep of the furnace.

I claim:

1. A furnace grate with water cooled bars, said grate having a double row of steps formed by the hollow bars superposed one above the other, said bars being curved in the shape of a U, the lateral branches of said U having a spread growing progressively from the upper bar, said upper bar being topped by a, hollow element shutting off in the upward direction the internal space of the grate which is located below and between the branches of said bars, passages being provided for the air required for the combustion, said passages connecting said internal space of said grate to the space external thereto, with the result that the surface presented by said steps is much greater than that embraced by the U of the lower bar and which would correspond to the surface of an ordinary horizontal grate for the same furnace.

2. A grate as claimed in claim 1 in which each bar as well as said hollow element is fixed to and connected to a hollow wall limiting said grate at one of its ends.

3. A grate as claimed in claim 1 in which each bar as well as said hollow element is fixed to and connected to a, hollow wall limiting said grate at one of its ends, said grate presenting for the general shape of its cross section a triangle, the apex of said triangle being located in the vertical median plane passing through the fire door of a cylindrical furnace. I

4. A furnace grate with water cooled bars, said grate having a double row of steps formed of hollow bars superposed one above the other, said bars being curved in the shape of a U, the lateral branches of said U having a spread growing progressively from the upper bar, said upper bar being topped by a hollow element which closes the space between the branches of said upper bar, and passages for air between said superposed bars, said passages connecting said space internal to said grate to the space external thereto, with the result that the surface presented by said steps is much greater than that embraced by the U of the lower bar and which would correspond to the surface of an ordinary horizontal grate for the same furnace, each bar as well as said hollow element being fixed to and connected to a hollow wall limiting said grate at one of its ends, said grate being of triangular cross section, the apex of said triangle being located in the vertical median plane passing through the fire door of a cylindrical furnace, the spread of the lateral branches of said lower bar being such that the lateral outer edges of said branches rest on the cylindrical wall of said furnace at the level which would be taken by an ordinary horizontal grate.

5. A furnace grate with water cooled bars, said grate having a double row of steps formed by hollow bars superposed one above the other, said bars being curved in the shape of a U, the lateral branches of said U having a spread growing progressively from the upper bar, said upper bar being topped by a hollow element which closes the space between the branches of the said upper bar, and passages for air between said superposed bars, said passages connecting said space internal to said grate to the space external thereto, with the result that the surface presented by said steps is much greater than that embraced by the U of the lower bar and which would correspond to the surface of an ordinary horizontal grate for the same furnace, each bar as well as said hollow element being fixed to and connected to a hollow wall limiting said grate at one of its ends, said grate being of triangular cross section,

. the apex of said triangle being located in the vertical median plane passing through the fire door of a cylindrical furnace, the spread of the lateral branches of said lower bar being such that the lateral outer edge of said branches rests on the cylindrical wall of said furnace at the level which would be taken by an ordinary horizontal grate, said bars being of half crescent cross section, the superposed bars being spaced apart to form air passages.

6. A grate as claimed in claim 5, in which said hollow element is made of a tube having for the general shape of its cross section a crescent.

7. A grate as claimed in claim 4, in which said hollow wall is extended in an upward direction by a hollow wall inclined toward the front of the grate.

8. A grate as claimed in claim 4, in which said bars are made of tubes with circular cross section, said tubes being traversed crosswise by passages meant for the air required for the combustion, said superposed tubes being joined together on their entire length.

9. A grate as claimed in claim 4, in which said hollow Wall is opposite to the fire door.

10. A grate as claimed in claim 4, in which the space internal to said grate forms a pre-heating chamber for the air required for the combustion,

said internal space being closed in all directions ERNEST SIN GY.

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

UNITED STATES PATENTS Name Date Tait Nov. 11, 1913 Number

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