US2214404A - Furnace for solid fuels - Google Patents

Description

Sept. l0, 1940. E. J. B. cor-:NEN

y FURNACE FOR SOLID FUELS Filed Nov. 2, 1937 1a 461? 3259152a49 2024 gmmm/ Patented sept. 1o, 1940 ff' STATES FURNACE vFOR SOLID FUELS Edouard Jean Baptiste Coenen, Brussels,

. Belgium Appucation November 2, 1937, seriaiNo. 172,480

In Belgium November 5, 1936 '7 Claims.

The present invention relates to furnaces for solid fuels with forced draft wherein the fuel rests upon at least one inclined or slanting sup- V port, such as a slanting grate or dead-plate or sole, at the upper part of which an air inlet opening is provided. v Y

It has been found in practice that in such furnaces, after a rather short time of combush, tion, the intensity of ignition decreases matel0 rially. This 1s due, when the slanting support is a grate, to the fact that the clinkers `flowing upon it give rise to the formation of a cake which 'increases moreV and more in volume and chokes partly the air passages; consequently the air is allowed to pass only throughl a limited number of passageshaving a reduced section, and the formation of craters with blowpipe flames is observed in the mass of fuel.

The clinliers must then be removed in order to avoid a rapid lowering of the quantity of heat developed in the furnace.

Similarly, when the slanting fuel support consists of a dead-plate at the upper and lower ends of which an air inlet opening isI provided, the lower opening is also more or less rapidly obstructed and the conditions are similar to those existing in the above mentioned case of a grate.

YThe present invention has for its object to overcome these disadvantages in order to obtain a more uniform combustion and lengthen the period of timebetween two succeeding clinker removing operations.

To this end, the slanting fuel support of the furnace according to the inventionv is so arranged that the clinkers formed upon it are stopped before they reach the air inlet opening which is provided at the lower part of the slanting support.

According to a preferred embodiment of the invention, the abovesaid support is but slightly slanted and is cooled by means of water circulation.

When the slanting support consists of a deadplate at the upper and lower parts of which an air inlet is provided, said vair is conveniently delivered at the lower end of the dead-plate through a channel or duct provided in the latter.

According to another feature, the lower end of the slanting fuel support presents at a higher ro level than the lower air inlet opening a flange directed upwardly. In such case the inclination of the support may be more steep, without inconvenience.

Another feature of the furnace according to the invention is that when the upper air inlet kati 'is placed between a dead-plate and a fuel guiding member arranged above the dead-plate, the upper end ofl this latter is located further from the'center of the combustion chamber than the lower edgeof the guiding member so that the '"5' fuel is prevented fromA reaching this upper end.

v According to still another feature of the invention, a single poker is located at the level of the upper vair inlet, at a place corresponding sub- Y stantiallyto the top of the clinker cake. l

Finally, according to another feature of the invention, when the fuel is fed from a bunker connected to the topof the combustion room by 'at least one feeding channel, a cooling water pipe is located in said channel. '1"5 Other details and features of the invention will appear in the following description of th-e accompanying drawing showing, as an example, an embodiment of the furnace.

' Fig. 1 is a perspective view, some parts being 2o broken away, of a furnace according to the invention.

Figure 2 is a `partial vertical cross sectional view through the furnace parallel to its front walland illustrates the hollow for the water :25 circulation in the furnace.

In the drawing, l indicates a water circulation furnacecomprising two juxtaposed units la and Ib.l It is understood that any number of such units may be provided according to the amount f3() of heat required.

" Each of said units comprises two inclined supports assuming the form of but slightly slanting hollow dead-plates. Fuel is fed on these deadplates by distributing channels 3 from a fuel "35 bunker 4. Conveniently a guiding member 5 is provided above each of said dead-plates 2, to guide the fuel coming down through these channels 3.

Between each of these guiding members 5 and 4 the top of the respective dead-plate 2, a branch 24 of a bifurcated air conduit, 24, 2a is provided for the inlet of air under pressure. The latter is delivered for example by a blower (not shown), through pipes opening at 6 into air boxes 'l pro- 45 vided at either side of the combustion room of the furnace. Part o-f the air passes through the other branch 2a of said bifurcated conduits, which is formed in each of the dead-plates 2 and flows out of the same at their lower ends. How- 50 ever, as the thickness of the fuel bed is very great at this place, the air can only passl with difficulty and has therefore a tendency to pass nearly in the direction of arrow :r through the branch 24 only, i. e. where the fuel'bed is not very thick. 55`

After the combustion has lasted for some time clinkers are being formed in front of said passage tending to choke it more or less completely, while part of said clinkers flow downwards upon the dead-plate tending to obstruct as well the lower opening or branches 2a.. But as the hollow dead-plates have according to the invention only a slight slant and are cooled by water circulation, these clinkers are stopped before reaching said lower opening. Consequently when the air passage provided at the top of the dead-plates 2 is choked, the main part of the air under pressure entering at 6 passes through the branches 2a, becomes heated there and flows out at the lower end of the dead-plates 2. The combustion of the fuel will thus progress normally and the necessity of removing the clinker-cake formed upon each dead-plate will arise much later than in the known furnaces.

The cooling water is supplied by a pipe 8 connected with the interior of the hollow deadplates 2 by means of the conduits 9. The water owing out of the top of the dead-plates 2 enters the guiding members 5 and through conduits Il! reaches the hollow dome II of the combustion room of the furnace, an outlet pipe I2 being connected to said dome.

To this cooling of the dead-plates 2 by this water circulation is to be added the cooling effect of the air passing through branches 2a.

On the other hand, according to another em- -bodiment of the invention, in order to prevent the fuel from reaching the upper end of said branches 2a and from entering the same, said end is located further from the center of the combustion chamber than the lower edge of the guiding member 5 placed above the corresponding dead-plate.

Furthermore, to allow the removal of the clinkers, pokers I3 have been provided according to the invention, said pokers being located at the top of the dead-plates 2, at the places corresponding to the upper part of the clinker cake formed upon each dead-plate 2.

When these pokers, which are handled from the front of the furnace by means of a device forming no part of this invention, are advanced into the position shown in dotted lines, the whole clinker cake formed upon each dead-plate and which on account of the cooling water circulation does not adhere to the dead-plate is caused to rock about its lower edge, and its upper end is shoved out of the fuel bed. 'Ihis upper end becomes thus quite free and can be removed through a door (not shown) provided in the front wall of the furnace.

On the other hand, in order to prevent the fuel from distilling in the channels 3, a cooling water conduit Il) has been provided according to the invention through said channels 3. In the case of Fig. l, this conduit Ill is a part of the cooling water circulation.

In order to allow the control of the thickness of the fuel bed upon the dead-plates there has been provided furthermore at the upper of each of them a vertically sliding damper 22 adapted to be lifted and lowered from the front of the furnace, by means of a device which is no lpart of the invention.

As shown in the drawing, the furnace comprises at its lower part, above the ash pit I5, a grate I 5 supported by projections I'I provided upon the conduits 9.

In each half of the furnace an opening has been provided in one of the front or back walls,

at a level lower than that of the grate I 6', to allow the operation of the furnace by natural draft.

The openings have each a closing member so that they may be closed, for example when air under pressure is supplied to the furnace, that is, when the furnace operates under forced draft. Furthermore, in order that the combustion may be limited to one half of the furnace, that is to the dead-plate or dead-plates on one side of the furnace, the ash pit I5 is divided in two halves by a vertical partition 23 placed underneath the pipe 8 and dampers or other closing devices (not shown) are placed in both branches of the bifurcated pipe ending at the openings `6, Ii provided in the air boxes 'I, l. Closing one o-f these dampers is thus sufficient to prevent the air from entering the corresponding air box I and to let it enter only the other air box 'I.

This arrangement has the great advantage ofv allowing the use of only half of the heating power of the furnace, as for example at the beginning of the winter, in case the furnace is used for heating the water of a hot-water central heating plant.

Furthermore, openings I8 are provided in the walls I9 which separate the air boxes 'I from the ash pit I5.

Before the openings I8 of each of the walls I8 a hand damper 28 with openings 2I is provided. When these openings have been caused to register with the openings I8 or when the damper has been placed so that the openings 2I lie between the openings I8, the connection is correspondingly established or cut between the ash pit I5 and the respective air box l.

According to another feature of the invention, in order to stop the clinkers still more surely before they may reach the opening for the inlet of the air under pressure provided at the lower end of the inclined supports, dead-plates or grates, for the fuel, each of these latter is provided with an upwardly directed flange, such as I4, said flange being placed at a higher level than that of the opening at said lower end.

It is obvious that fuel supports provided with such a flange may have a greater inclination than in the figure, the clinkers being however positively stopped before they reach the lower air inlet opening.

It is to be understood that this invention is not exclusively limited to the embodiments shown and that many alterations may be made in the shape, the number, the arrangement and the constitution of the parts forming the invention without departing from the scope of the appended claims.

What I claim is:

1. A forced draft solid fuel furnace comprising a combustion chamber, a hollow support inclined at less than 30 to the horizontal through which a cooling uid passes and upon which the fuel is designed to rest in said chamber, a bifurcated air conduit having a rst branch opening in said chamber at the upper portion of said support and a second branch opening in said cham.- ber at the lower portion of said support, and an inclined guiding means in said chamber for the fuel, said guiding means being placed above the level where said rst branch opens in said charn-y ber in such manner that the lower edge of said guiding means extends nearer to the center of said chamber than the upper end of said support, whereby there is formed under said guiding means an accumulation pocket for the fluid clinkers formed at the level where said first branch opens in said chamber.

2. A forced draft solid fuel furnace comprising a combustion chamber, an inclined support upon which the burning fuel is designed to rest in said chamber, a bifurcated air conduit having a first branch opening in said chamber at the upper portion of said support land a second branch opening in said chamber at the lower portion of said support, a flange upon the lower end of said support directed upwardly and located at a level above the level where said second branch opens in said chamber, and inclined guiding means in said chamber for the fuel, said guiding means being placed above the level where said first branch opens in said chamber in such manner that the lower edge of said guiding means is nearer the center of said chamber than the upper end of said support so as to form under said guiding means an accumulation pocket for the fluid clinkers formed at the level where said first b-ranch opens in said chamber.

3. A forced draft solid fuel furnace comprising a combustion chamber, a hollow support inclined at less than 30 to the horizontal through which a cooling fiuid is designed to pass and upon which the burning fuel is designed to rest in said chamber, a bifurcated air conduit having a iirst branch opening in said chamber at the upper portion of said support and a second branch opening in said chamber at the lower portion of said support, said second branch being located in said support, and inclined guiding means in said vchamber for the fuel, said guiding means being placed above the level where said first branch opens in said chamber in such manner that the lower edge of said guiding means extends nearer the center of said chamber than the upper end of said support soas to form under said guiding means an accumulation pocket for the fluid clinkers formed at the level where said first branch opens in said chamber.

4. A forced draft solid fuel furnace comprising a combustion chamber, an inclined support in said chamber upon which the burning fuel is designed to rest, a bifurcated air conduit having a first branch opening in said chamber at the upper portion of said support and a second branch opening in said chamber at the lower portion of said support, said second branch being located .withinsaid support, a flange upon said support extending upwardly above the lower end of said support and located at a higher level than the level where said second branch opens in said chamber, and inclined guiding means in said chamber for the fuel, said guiding means being located above the level where said first branch opens in said chamber in such manner that the lower edge of said guiding means is closer to the center ofv said chamber than the upper end of said support, so as to form under said guiding means an accumulation pocket for the fluid vclinkers formed at the level where said first b-ranch opens in said chamber.

, 5. A forced draft solid fuel furnace comprising a combustion chamber, an inclined support in said chamber upon which burning fuel is designed to rest, a bifurcated air conduit having a first branch opening in said chamber at the upper portion of said support and a second branch opening in said chamber at the lower portion of said support, said second branch being connected substantially at right angles to said first branch, means for stopping the fluid clinkers, and an inclined guiding plate in said chamber for the fuel, said plate being located above the level where said first branch opens in said chamber in such manner that the lower edge of said guiding means is nearer the center of said chamber than the upper end of said support, so as to form under said plate an accumulation pocket for the fluid clinkers formed at the level where said first branch opens in said chamber.

6. A forced draft solid fuel furnace comprising a combustion chamber, an inclined support in said chamber upon which the burning fuel is designed to rest, a bifurcated air conduit having one branch opening in said chamber at the upper portion of said support and another branch opening at a lower level in said chamber, a single poker located adjacent the level where the first-mentioned branch opens in said chamber, said poker being of sufficient length so as to eX- tend sufciently far within said chamber so as to push back the top of the clinker formed across the fire bed, even thoughsaid bed has a maximum thickness.

7. A forced draft solid fuel furnace comprising a combustion chamber, an inclined support in said chamber upon which the burning fuel is designed to rest, a bifurcated air conduit having one branch opening in said chamber at the upper portion of said support and another branch opening at a lower level in said chamber, a single poker located adjacent the level where the first-mentioned branch opens in said chamber, said poker being adapted to be moved in such a direction relatively to said inclined support, that the force exerted in the direction of movement of said poker produces with relation to the lower edge of said support a rotation moment and the length of movement of said poker being such that said poker may push back the top of the clinker formed upon said support across the combustible layer even when said layer has its greatest thickness.

EDOUARD JEAN BABTISTE COENEN.

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