US1811657A - Furnace for burning pulverized fuel - Google Patents

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)une 23, 1931. w, R WOOD 1,811,657

FURNACE FOR BURNING PULVERIZED FUEL original Filed Jima 16, 1925 v.f/f Y INVENIOR fm 5 ATTORNEYS Patented `lune 23, 1931 UNiTED sTATEs PATENT OFFICE WILFRED R. WOOD, OF LONDON, ENGLAND, ASSIGNOR TO INTERNATIONAL COMBUS- TION ENGINEERING CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELA- WARE FURNACE FOR- .BURNING PULVERIZED' FUEL Application led Tune 16, 1925, Serial No. 37,428, and in Great Britain September 26, 1924. Renewed March 13, 1931.

This invention relates to impi'ovements in furnaces for burning finely divided fuel 1n suspension particularly as regards the manner of disposing of asli and refuse. .v

In the burning of pulverized fuel difficulties are encountered because of the ash and refuse becoming fused due to high temperatures, which results in slag formations of an objectional nature, not to be easily removed.

Spaced cooling tubes across the furnace below the zone of combustion have been provided heretofore for lowering the temperature of the ash particleswith theresults that the above dilliculties have been greatly obviated.

I aim to provide an limprovedarrangement of cooling means for overcoming slagging and fusing diiculties in a simple, inexpensive a'nd effective manner. p

More specifically stated, it is an object of this invention to provide the combustion chamber of the furnace with a hopper shaped bottom, having surfaces rovided' with tubes thru which a heat absor ing medium is circulated, whereby the temperature of the ash is lowered below fusion temperature.

How the foregoing, together with such other objects and advantages as may hereinafter appear, or are incident to my invention, are realized, is illustrated in preferred form iii the accompanying drawings, wherein Fig. 1 is a vertical longitudinal section thru a pulverized fuel burning furnace for carrying out my invention; and

Fig. 2 is a section taken on the line 2-2 of Fi l.

leferring now more particularly to Fig. l the combustion chamber is indicated by the reference letter A, the lower portion of any suitable type of boiler b the reference letter B, the burner or fuel elivery means at C, and the ash pit at the bottom of the combustion chamber at D.

In the present instance fuel and air are introducedv thru the burner or burners C in a downward direction, and take-s a U-bend in the zone of combustion a-nd passes out thru the outlet 5, under control of the draft. The hot gases and products of combustion in passing thru the outlet 5 generate steam in the boiler B, tubes of which extend across vthe outlet opening. Auxiliary damper controlled inlets 6 are provided at various points in the front wall of the furnace.

The bottom of the furnace or ash pit is of hopper shape, the inclination of the sides 7 and 8 thereof being greater than the angle of repose of the refuse or ash, so that such particles will gravitate tothe bottom of the pit as will hereinafter more fully appear.

The inner surfaces 9 and 10 of the ash pit D. and the lower portions of the front and rear upright walls are provided with cooling means extending thereover, such means fin this instance being shown as a plurality of closely spaced tubes 11 thru which cooling fluid, preferably water is caused to flow, such extend from the lower part of the ash hopper or pit D upwardly for soine distance adjacent the inside surfaces of the combustion 'chamber A, thus providing cooled wall surfaces as well as cooled ash pit surfaces, making it possible to decrease the size of the combustion chamber and/or the boiler proper, besides protecting the upright walls.

I have shown the tubes 11 provided with overlapping fins 18, (see Fig. 2), sov that a more or less continuous cooling surface is provided. It is to be understood, however, that this continuous surface may be formed in 'other ways, as for example, by providing grooved metallic blocks closely fitting the tubes llso as to conduct heat received by radiation to all parts of the tubes.

It will be seen from the foregoin that the ash and refuse which gravitate uring the burning of the fuel will lodge on the cooling surfaces and such surfaces being cool, particles will be cooled and take a granular-like form, with the result that, be-

cause of the angle of inclination, they will gravitate.

The arrangement is particularly useful where vertical firing is employed because this form of tiring has a tendency to throw down refuse particles. In addition the cooling surfaces, because they are subject to radiant heat, evaporate such large quantities of Water as to make it possible to materially cut down the size of the boiler proper, and to greatly increase the capacity of an vexisting boiler if added thereto. The arrangement is also one which reduces the amount of dead space required in the combustion chamber as the flames may be brought further down than heretofore possible. This means that a. smaller combustion chamber can be utilized, or stated in another way, that more fuel can be burned in a combustion chamber of given size.

The opening 2O at the bottom of the ash it D may be of such dimension as to allow tree passage of the particles of ash and small clinlrer. Any suitable form of discharge openingsat the lowest part of the incline, however, may be provided.

I have shown a trough Q1 of necessary eX- tent below the opening 2O preferably containing water for receiving the refuse from whence it may be removed in any suitable manner, such trough also serving to prevent passage of air in through the opening Q0.

In some instances, it may be desirable to to have the tubes ll constitute superheater tubes, or part superheater tubes and part water circulation tubes connected into the boiler circulation. lVhen superheater tubes are used, such tubes are connected to the steam space of the boiler.

lei-tain of the advantages herein pointed out are effectively realized by virtue of the fact that very rapid circulation is obtained thru the cooling tubes.

I claim:

l. In a furnace for burning finely divided fuel in suspension. a boiler, a combustion chamber having substantially upright walls and a sloping bottom portion therebelow, a plurality of closely spaced tubes lining the sloping bottom portion and extending up wi hin the combustion chamber adjacent an upright Wall thereof, each of the said tubes lying in a substantially upright plane and having within the furnace and bottom thereof fin members at opposite sides, the fins on one tube beine' in substantial juxtaposition to the fins on adjacent tubes to form a continuous metallic surface, the said tubes being bent at their upper ends to extend outthrough a wall of the combust-ion chamber, and means connecting said tubes into the circulation of the boiler.

2. In a furnace for burning finely divided fuel in suspension, a boiler, a combustion I chamber having substantially upright walls and a sloping bottom portion therebelow, a plurality of closely spaced exposed tubes lining the sloping bottom portion and extending up Within the combustion chamber adja cent an upright `wall thereof, each of the said tubes lying in a substantially upright plane and having lin members at the opposite sides thereof, the tins on one tube overlapping the fins of the adjacent tubes, the upper ends of said tubes extending through a wall of the combustion chamber, and means connecting the said tubes into the circulation of the boiler.

3. In a. furnace for burning finely divided fuel in suspension, a boiler, a combustion chamber having upright Walls and a sloping bottom for discharge of refuse, a plurality of closely spaced exposed tubes lining the bottom and disposed at an angle greater than the angle of repose of refuse particles and exposed water-tube-wall portions lining at least a substantial part of upright walls adjacent the bottom of the chamber and connected for circulation whereby heat is absorbed in substantial quantities above the said bottom.

4. In a furnace for burning finely divided fuel .in suspension, a boiler, a combustion chamber having upright Walls and a sloping bottom for discharge of refuse, a plurality of closely spaced exposed tubes lining the bottom and disposed at an angle greater than the angle of repose of refuse particles and exposed water-tube-wall portions lining at least a substantial part of upri ht walls adjacent the bottom of the cham er and connected for circulation whereby heat is absorbed in substantial quantities above the said bottom, the said tubes and the water tube wall portions being in series connection.

5. In a nurnace for burning finely divided fuel in suspension, a boiler, a combustion chamber having upright walls and a hopper shaped bottom having a centrally disposed discharge: orifice, two sets of closely spaced exposed tubes lining the sloping sides of the bottoml and disposed at angles greater than the angle of repose of the refuse particles, and two exposed water tube-wall portions dining two opposite upright wall portions adjacent the bottom of the chamber and connected in series with said tubes, the tubes and the water tube wall portions being connected into the circulation of the. boiler.

In testimony lwhereof, I have hereunto signed my name.

lV. R. IVOGD.

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