US2420373A - Hot-blast stove - Google Patents

Description

- Patented May 13, 1947 UNITED STATES PATENT V OFFICE HOT-BLAST s'rovn Carl G. Hogberg, Glenshaw, Pa., assignor to United States Steel Corporation of Delaware, a corporation of Delaware Application September 15, 1944, Serial No. 554,242

The present invention relates to improvements in hot blast stoves such as those used to preheat the combustion air supplied to a conventional form of blast furnace. I

A primary object of the invention is to provide a hot blast stove having. a combustion chamber and a checker chamber with an upright division wall between them including a stratum of heatinsulating material eflfective to retard the transfer of heat through the division wall so as to substantially equalize the temperature throughout the entire cross-sectional area. of the checker chamber at any desired horizontal'plane or. zone of the stove.

A further object of the invention is to provide such a division wall having incorporated therein a layer of material of lower heat conductivity than that of the remainder of the wall.

A more detailed object of the invention is. to provide a division'wall between the combustion chamber and the checker chamber of a hot blast stove with a heat-insulating material of graduated heat conductivity incorporated therein,

which is effective to variably retard the transfer of heat through the division wall at different elevations or zones, so as to substantially equalize the temperature in the checker chamber at such various zones of the stove.

For a more complete disclosure of the invention, reference should be made to the following detailed description, the accompanying drawings, and the appended claims.

In the drawings:

Figure 1 is a vertical longitudinal section through a hot blast stove embodying the invention.

5 Claims. ((1263-19) 2 supplied during the heating cycle. During such cycle the air and gas are intermingled and burned in the combustion chamber 20, and the Products of combustion flow through the numerous passageways formedby the checkerbrick flyth'us" giving up their heat thereto. The products of combustion then pass to a suitable stack (not shown) by way of an exhaust port 30. .When the stove is on blast, cold air enters through port 32,

passes upwardly through the multiplicity of flues' and 2, there is incorporated in the division wall an interior layer of material It characterized by a lower rate of heat conductivity than the portions lB and l8 of the wall. The portions l8 and 18 may be formed of the conventional type of refractory brick normally used in hot blast stove construction and the material forming the stratum IE will be of a character to retard the transfer of heat through the division wall for the express purpose of substantially equalizing Figure 2 is a horizontal section on line II--Il of Figure 1.

Figure 3 is a fragmentary detail of a portion of the division wall between the combustion and checker chambers of the stove, including a stratum of heat-insulating material of varying heat conductivity at different horizontal zones of the stove.

Referring in detail to the drawings, reference numeral l0 represents the outer annular refractory brick wall of the stove which is usually enclosed by a substantially cylindrical steel shell l2. At the top there is in substantially semispherical brick roof l4 covered by a dome-shaped the temperature in the checker chamber throughout substantially the entire cross-sectional area thereof at any desired horizontal zone or region of the stove. As illustrated in Figure 3, the thickness.

of the stratum of heat-insulating material It may vary at different elevations of the furnace, so as to provide a predetermined heat conductivity gradient. Instead of varying the thickness of the stratum I 8, it may be of uniform thickness throughout but of differing densities or compositions at different elevations to provide any desired gradient of heat conductivity. The thickness of the heat-insulating material may be gradually increased from bottom to' top, or vice versa, and may be entirely omitted at a predetermined point in the height of the wall, to suit the design or requirements of any given size of stove.

The herein claimed invention overcomes a troublesome problem which is inherent in hot blast stoves of conventional form. In such conventional stoves, during both the checker heating and air heating periods, the average temperature in the lower portion of the combustion chamber is considerably higher than the average temperature in the lower region of the checker chamber. This temperature differential may vary from approximately 600 F. to 1400" F.

during the air heating cycle, and from approximately 1500 F. to 2250 F. during the checker heating period. Due to the higher average temperature in the lower portion of the combustion chamber, during both the checker heating and air heating periods, the refractory checkerwork immediately adjacent to an uninsulated division wall will be higher in temperature than the checkerwork more remote from the division wall. This difference in temperature in prior'art construction is of sufllcient magnitude to induce a differential expansion and contraction of the checkerwork in a given horizontal plane of the checker chamber, with resultant damage or destruction of the checkerwork or supports therefor in the base of the stove. The claimed invention overcomes this shortcoming inherent in prior art constructions by substantially equalizing the temperature of the checkerwork throughout the cludlng an outer annular brick wall, an upright entire cross-sectional area at any given horizontal plane or region of the stove.

While I have illustrated the invention as embodied in a type of hot blast stove having a combustion chamber of approximately elliptical form, it will be understood that the invention is also applicable to hot blast stoves in which the combustion chamber is formed by an inner substantially circular wall either concentric to or tangent to the outer wall, it being obvious that the principles of the invention will apply by incorporating a body of heat-insulating material in any wall separating the combustion chamber from the checker chamber.

I claim:

1. A hot blast stove for heating blas: furnace combustion air, comprising an upright, substantially hollow structure having an upright division wall dividing the interior of the stove into a combustion chamber and a checker chamber, said division wall including outer strata of fire-brick separated by a dissimilar stratum of heat-insulatin material effective to retard the transfer of heat through said fire-brick strata.

2. A hot blast stove for heating blast furnace combustion air, comprising an upright, substantially hollow structure-having an upright division wall dividing the interior of the stove into a combustion chamber and a checker chamber, said division wall including outer strata of firebrick separated by dissimilar stratum of heatinsulating material of graduated heat conductivity effective to retard the transfer of heat through said fire-brick strata so as to substantially equalize the temperature throughout the entire area of the checker chamber at any desired horizontal zone thereof.

division wall, a body of checker brick between one face of said division wall and said annular wall, and a combustion chamber bounded by the other face of said division wall and said annular wall, said division wall consisting of two layers of conventional refractory brick spaced apart by a layer of material of lower heat conductivity than that of the refractory brick, the composite wall being effective to retard the transfer of heat therethrough so as to substantially equalize the temperature in the checker chamber at any desired horizontal zone thereof.

4. A hot blast stove for heating blast furnace combustion air, comprising a hollow structure having an outer annular brick wall, an upright division wall, a-body-of checker brick between one face of said division wall and said annular wall,

and a. combustion chamber bounded by the other face of said division wall and said annular wall, said division wall consisting of two layers of refractory brick spaced apart by an interior brick layer of material of lower heat conductivity than that of the brick layers, the composite division wall being eflective to retard the transfer of heat therethrough so as to substantially equalize the temperature in the checker chamber at any desired horizontal zone thereof.

5. A hot blast stove for heating blast furnace combustion air, comprising a substantially hollow structure including an outer annular brick wall, an upright division wall, a, body of checker brick between one face of said division wall and said annular wall, and a combustion chamber bounded by the other face of said division wall and said annular wall, said division wall consisting of two layers of refractory brick spaced apart by a layer of insulation of graduated heat conductivity to substantiall equalize the temperature in the checker chamber at various horizontal zones of the stove.

CARL G. HOGBERG.

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

UNITED STATES PATENTS Number Name Date 1,849,657 Boynton Mar. 15, 1932 2,049,815 McGee Aug. 4, 1936 2,257,453 Bowland Sept. 30, 1941

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