US1729022A - Furnace for burning finely-divided fuel - Google Patents

Description

gm 24, .1929. w. R. wow 1,729,022

7 FURNACE FOR BURNING. FINELY DIVIDED FUEL Filed June l6,' 1925 3 Sheets-Sheet 1 Sept. 24, IQZQ.

\MR. wooD FURNACE FOR BURNING FINELY DIVIDED FUEL 3 Sheets-Sheet .2

Filed June 16, 1925 CH5 9 00C 05w 0 w I a W 4 Sept. 24, 1929. w. R. wooD 1,729,022

FURNACE FOR BURNING FINELY DIVIDED FUEL Filed June 16, 1925 5 Sheets-Sheet 3 Snow V601,

747% v8 WW0 Patented fiept. 24, 192% NiTEn STATES PATENT OFFICE WILFRED B. WOOD, OF LONDON, ENGLAND, ASSIGNOR TO INTERNATIONAL COM- BUSTION ENGINEERING CORPORATION, OF NEW YORK, N. Y., A. CORPORATION OF DELAWARE Application filed June 16,

This invention relates to furnaces and is particularly useful where the fuel 1S burned in a fine state of division, such as powdered -coal.

Its nature, objects and advantages will be best understood from the following brief statement of previous practice:

From the beginning the difiiculty encountered in the burning of pulverized fuel, particularly under boilers, has been the destruction of the brick work.

To overcome this difficulty fuel has been admitted in a downward direction to obtain a long flame, and air for combustion has been successfully supplied to the fuel so that a soft flame was secured not characterized by any localized regions of intense temperature. This involves extensive overhead suspended arch construction and also a somewhat expensive multi-ported vertical wall construction. To increase efficiency it has also been proposed to preheat the combustion air, which has been done by providing somewhat complicated and expensive hollow wall construction.

It has also been contemplated to locate within the combustion chamber, evaporating means, such as screens or walls composed of tubes. These tubes, among other things, serving to protect the walls.

In the foregoing practices, each installation was in effecta separate engineering undertaking, for which special designs were developed, it being practically impossible to standardize on any equipment with the possible exception of some minor items, such, for example, as burners and castings for air 'inlets and the like. Furthermore, in adapting any of these features to existing furnace constructions, an individual engineering problem was presented, the complications being met by special design.

It is one of the main objects of the invention to simplify construction whether in new installations or in the adaptation of existing installations; and to cheapen cost of new installations or the changing over of existing installations; and to secure a very wide range of standardization on essential features FURNACE FOR BURNING FINELY-DIVIDED FUEL 1925. Serial No. 37,424.

whereby much of the'engineering work is cut down.

Another object of the invention is to so burn the fuel that the foregoing may be put into effect.

How these, together with such other objects as may hereinafter appear, or are-inci-- dent to my invention, are realized, is illustrated in the accompanying drawings, wherein Fig. 1 is a vertical section thru the furnace and boiler embodying my invention,

Fig. 2 is a section taken on the line22 of Fig. 1,

Fig. 3 is a section taken on the line 3-3 of Fig. 2,

Fig. 4 is a section similar to Fig. 2, but illusrating a modification of my invention, an

v Fig. 5 is a fragmentary section illustrating another modification.

In practicing my invention, I first propose to burn the fuel with a short flame to which end I supply practically all of the air for combustion with the fuel, using for the purpose any suitable design of burner, of which there are a number in this art.

The short flame enables me to effect combustion in a small combustion chamber, hence in new installations,-the combustion chamber may be small, and the invention may be applied to existing installations such, for example, as stoker fired furnaces, because such furnaces are small.

If now I introduce the fuel in a downward direction in a portion of the combustion chamber and admit substantially all of the air for combustion with the fuel, the length of the flame, under maximum rating conditions,

can be readily determined and thus the height of the burners from the bottom of. the combustion chamber can be readily determined, which fixes the height of the combustion chamber. Assume, for example, an existing stoker fired installation which is to be converted into a pulverized fuel burning installation. It is usually necessary in such case to build a Dutch oven extension in front of the combustion chamber, for which purpose the front wall is removed. The height of this Dutch oven extension can be standardized be cause the maximum flame travel is known. Such a Dutch oven extension can be placed almost without exception on existing nstallations. Obviously it can be provided in a new installation. However, with the short length flame which results in this method of burning, that portion of the turnace wall adjacent to which the fuel is admitted, will be subject to rapid destruction. if new we provide evaporating means, such as tubes adjacent such portion of the Wall, we may protect the wall by the cooling action of the tubes. These tubes are of standardized length for the height of the Dutch oven is standardized.

The horizontal depth of the Dutch oven ex tension is also standardized for it is only necessary to removed the burners sutliciently tar from the furnace outlet to allow the fuel and flame stream to bend, somewhat after a U fashion, to the outlet.

Thus the horizontal depth to which the protecting tubes must be carried may also be standardized.

Therefore, there remains to be determined the matter of the horizontal width of the combustion chamber and this is a variable. Hence the only items as to which there may be variation are the headers into which the tubes are connected, and even these may be carried in several sizes, various combinations of which will suffice to meet the range of variation in furnace width.

From the foregoing it will be seen that. given certain limited information, a standard set of prints'may be supplied with standard apparatus. from which the installation can readily be made.

Referring now to the drawings, it will be seen that I have illustrated, by way of ex ample, a horizontal boiler 7, below which is the combustion chamber 8, having its outlet 9 in the upper part thereof. The reference character A denotes the extension. This extension has its wall protected by a box-like arrangement of tubing B comprising a front water wall of tubes 10 and two side water walls of tubes 11 and i2, the side tubes being connected respectively into upper and lower headers 13 and 14 and the front wall tubes being connected into upper and lower headers 15 and 16. At the top of this box I preferably supply another set of inclined tubes t7, the lower ends of which are connected into the header or headers 15 and the upper ends of which are connected into the header or headers 18. By referring to Fig. 3. it will be seen that I have made the box of two units having an appropriate number of headers. The headers 16 at their outer ends have fittings 1.). by virtue of which suitable down-' headers 13 to the headers 18. Thus, all of the tubes of the box constitute upcomers.

The tubes being and the front wall of the furnace protect such walls and the fuel is admitted in a down ward direction into the upper part of the llutch oven extension thru the burners 23, the tubes 17 being arranged in spaced groups as shown in Fig. 1 to permit of such introduction of the fuel.

No complicated arch is required as the top of the box may be closed by a suitable sheathing 2-1 carried on the tubes 17. The front wall and the side walls and the rear wall may be made of simple brick construction, that portion surrounding the cage or box of tubing being comparatively thin.

By this arrangement it is possible to dispense with any protection of the bridge wall and portions of the side walls to the rear of the box, for the reason that the fuel is burned with a short flame, the hottest portion of which is in the region of the extension. The extension is protected by the tubing and this tubing by virtue of the fact that it is subjected to radiant heat and because there is a very rapid circulation therethru has a tendency to reduce the temperature of the flame by an absorption of heat therefrom to a point where such portions of the flame as carried over into the unprotected regions have a temperature not excessively detrimental to the brick work.

The box of tubing constitutes a very efiective evaporating medium in consequence of which, in new installations, the size of boiler 7 may be cut down.

The box, all the tubes of which would be of standard length, is made up to the required width and shipped and installed as a unit, the downcomer and upcomer connections be ing made at the installation.

lVhcrc ditiiculties are encountered with slagg'ing of the refuse because of the fusing temperature of the ash, a water screen C may also be provided as part of the unit. This water screen consists of tubes spaced far enough apart to permit the gravitating particles to freely pass to the hopper 26, such refuse particles in passing from the screen being cooled below the point at which the deposit thereof will run or coalesce into a mass of slag. These tubes '25 are oi standard length for a given type of boiler and they are connected into the header or headers 16 at their lower ends. and to the header or headers 27 at the upper end. which headers in turn are connected by an upcomer or upcomers 28 to the boiler. The number of these tubes may vary in accordance with the width of the furnace as will the length of the header or headers 27.

From the foregoing it will be seen that it is possible to obtain a degree of standardization heretofore impossible and that standard tjacent to the side walls araaeee engineering design and units may be supplied to various types of boilers-without restoring to individual engineering for each installation. The furnace will be more eco-= nomical both as to first cost and the matter of repairs. The cost of construction of the protecting elements will be reduced in proportion to the capacity for standardization.

In Fig. 4 I have shown my invention as applied to a boiler somewhat after the Stirling type, the arrangement being substantially as described, the type of connections varying simply to meet the differences in the general arrangement of the parts of the boiler.

If desired the vertical tubes of the box may be provided with longitudinally extending fins which cooperate with the tubes to forma wall. With this arrangement the number of tubes is cut down and it is possible to obtain effective connection of the tubes into' ing provided with longitudinal fins 29 for this purpose.

Hastening of the combustion may be furthered, if desired, by other arra'n ements of the burners or any method of com ustion directed toward that end. By way of illustration as to the size of the combustion chamber and of the box of tubing, I would direct attention to the fact that in many modern installations employing vertical firing of the pulverized coal an overall flame length from 40 to or feet is approved whereas, by my invention I can accomplish the same results with the flame length much smaller, say, for example, from 10 or 15 to 20 or 25 feet.

7 Other advantages of my invention will occur to those familiar with the art.

I claim: In a combustion chamber for burning finely divided fuel, means for introducing the fuel and the air for combustion into the combushaving an open side enabling the boxes to be so associated as to form a single combustion chamber, said refractory box having an outlet opening at the upper art thereof through which the products 0 combustion pass, a boiler arranged across said outlet, and an ash pit for the combustion chamber.

In testimony whereof, I have hereunto signed my name.

WILFR'ED R. WOOD.

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