US1833677A - Furnace wall construction - Google Patents

Description

Nov. 24, 1931.

c. E. IHAWKE 1,833,677

FURNACE WALL CONSTRUCTION Original Filed'May 2, 1925 2 SheetsSheet 1 INVENTOR I 4; A; Zr/M 6W, WW

Nov. 24, 1931. c E. HAWKE FURNACE WALL CONSTRUCTION 1923 2 Sheets-Sheez iginal Filed May 2 INVENTOR Patented Nov. 24, I931 s'mrss T orator CLARENCE E. HAWKE, OF METUCHIEN, NEW JERSEY, ASSIGNOR TO THE CARBORUNDUM COMPANY, OF NIAGARA FALLS, NEW

YORK, .A,v CORPORATION OF PENNSYLVANIA FURNACE WALL CON STRUCTIGN Application filed May 2, 1923, Serial No. 636,146. Renewed October 24,1929.

This invention relates to furnace wall constructions, and is particularly adapted'to be used around the combustion chamber of a furnace. There is a growin tendency to work furnaces at extremely high rates of combustion. Under the increased temperatures resulting from such practice, the setting quickly burns out and when coal is used as a fuel, the fused ash reacts with the brickwork and destroys the setting in a very short time. This is especially true with low grade coal, and when such fuel is used it is impossible to maintain heavy furnace loads regularly because of the rapid deterioration of the brickwork.

I overcome this dilficulty by providing a furnace wall lining of refractory-material having relatively high heat conductivity and means for cooling the back of the material. The preferred material is silicon carbide. Silicon carbide not only is a very good heat resisting refractory, but has a relatively high heat conductivity, so that the heat is conducted away from the face of the material which is exposed to the flame, whereby such viding preheated air for combustion.

In the accompanying drawings, illustrating more or'less diagrammatically my invention as applied to a coal-fired furnace.

Figure 1 is a sectional elevation through a furnace taken on the line II}of Figure 2;

- Figure 2 is a sectional elevation through the furnace taken on the line Ill-11 of Figure 1 g Figure 3 is a section through another t pe of furnace, the air being supplied to the rnace above the grate, and i Figure 4 is a section of the furnace wall on the line lV-IV of Figure 3. 0

In the embodiment of my invention illuslow the grate 7 Plates 8 or brickwork of silicon carbide form the wall between the ducts 3 and the interior of the furnace, since this material is non-porous, very refractory, and possessed of a very high heat conductivity.

In Figures 3 and l, I have illustrated my apparatus as applied to another type of furnace wherein similar parts have been given the same reference character with the letter a suflixed. In this embodiment a conventional hopper type stoker is illustrated in chain lines and perforated blocks 9 are provided for introducing the air above the grate. The blocks 9 form a part of the combustion chamber walls and air is preferably supplied to them after it has passed through the air ducts 3a behind the refractory plates 8a. Air is supplied tothe ducts So from below the grate through an inlet 10 and its direction of travel is clearly indicated by arrows. Ijhave 8a above the perforated tuyere blocks 9 materially improves furnace conditions both from a standpoint of operating eificiency and long life.

It will be apparent that in both forms of the invention illustratedthe combustion found that the use of the refractory plates chamber has silicon carbide walls which not only extend within the zone of the fuel bed, but a substantial distance above such zone. As previously pointed out, when a poor grade of coal is used the fused ash reacts with the brick Work and destroys the setting in a very short time. This is particularly true in furnaces under boilers that are highly overrated, it having been found that the brick work above the fuel bed is destroyed prior to that portion in contact with the fuel bed. This results from the continual erosion of the side and bridge walls by the flow of deposited ash which literally runs down over these walls in a molten condition; By the present invention I have overcome this difficulty. The portion of the silicon carbide walls within the zone of the fuel bedis maintained at such a low temperature that clinkers will not adhere thereto, while the portion of the silicon carbide walls extending above the fuel bed is also cooled so that they are protected from the-destructive action of the fluid ash.

The invention has many advantages and 'is particularly valuable where furnaces are Worked under severe conditions, such as heavy rating or low grade fuel, as it maintains the furnace setting for a long period, with resulting economy in operation and freedom from care.

lVhile I have shown and described certainpreferred embodiments of-my inventionitwill. be understood that the invention is not limited to these precise embodiments, but that it may be otherwise embodied within the scope of the appended claims.

1. In a furnace, a. combustion chamber, said combustion chamber having side walls and a bridge wall provided with facings of silicon carbide, said silicon carbide facings having many times the thermal conductivity of fire-clay refractory material and extending within the zone of the fuel .bed and a substantial distance above said zone, and a duct back of said facings through which cooling air is circulated in contact with the rear Walls of the facings throughout the major portion of the area thereof, a portion of saidfacings above said zone being imperforate, and a portion thereof within's'aid zone being perforate, said duct delivering to said perforate portion whereby the cooling air which circulates through said duct is conducted to walls of the combustion chamber and of many times greater thermal conductivity than fireclay refractory material, said portions extending both within the zone of the fuel bed and a substantial distance above said zone,

and a duct back of said wall through which cooling air iscirculated in heat conducting relationship to the portions of highthermal conductivity for cooling said portions to preabove said zone, a. duct back of said wall through which cooling air 1s circulated in heat conducting relationship to the portions of'high thermal conductivity for cooling said portions to prevent the adherence of clinkcrs thereto, means for securing forced circu lation of air through the duct, and means for conducting the preheated air from said duct to the combustion chamber.

In testimony whereof I have hereunto set my hand.

OLA RENCE E. HAWKE.

the fuel bed through said perforate portion in a highly preheated condition.

2.,I'n a furnace, .a main wall structure, a combustion chamber defined thereby, said main wall structure having certain portions thereof formin the walls of the combustion chamber of non-metallic refractory material of many times greater thermal conductivitv than fire-clay refractorymaterial,

said portlons extending both within the zone of the fuel bed and a substantial distance above said zone, and a duct back of said portions of high thermal conductivity providing an elongated circulating path covering substantially the entire area of such portions above the zone of the fuel bed for cooling the slag in contact with the inner surfaces of said portions to thereby form a protective covering therefor, the portions above the zone of the fuel bed being imperforate.

3. In a furnace, a main wall structure, a combustion chamber defined thereby, said main wall structure having certain portions thereof of refractory material forming the

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