US1746705A - Blast furnace - Google Patents

Description

Feb. l1, 1930. A H, KOPPERS 1,746,705

BLAST FURNACE Original Filed Sept. 29. 1922 Patented Feb. l1, 1930 HEINRICH KOPPERS, OF ESSEN, POSTFACH, GERMANY BLAST FURNACE Application led September 29, 1922, Serial No. 592,022. Renewed March l, 1927.

of the stack is chargeable to two mutually contributing factors, first, impact of incoming charges of ore, coke etc., against the wall and, second, weakening of that portion of the wall which receives the impact, by the wide fluctuations of temperature which occur in that region of the furnace. Thus, a range of temperatures running from 250o F. to 900 F. is not unusual in the upper lpart of the furnace and fluctuations of such magnitude, 0 occurring sometimes very suddenly, subject the material of the wallto severe strains which weaken its resistance to the impact of incoming charges. The best fire-brick or refractory lining thus far produced will crumble away, long before the remainder of the furnace has outlived its usefulness, owing to the breaking down of its cohesive strength under alternate expansion and contraction. It has been attempted to meet the difficulty by protecting the impact surface with Wearplates of steel or iron; but these also suffer deterioration, buckling and shifting until they become loosened and fall down into the charge. j

The primary object of my invention is to provide an improved construction for the top of a blast furnace in order to lengthen the term of its usefulness and reduce the eX- pense of repairs and replacements. A further object attained by my improved construction is the maintenance of a somewhat more uniform temperature within the upper part of the stack.

In carrying out my invention, I eliminate the customary brick lined wall at the top of the stack and substitute therefor a double walled steel cylinder or jacket in which a cooling medium, preferably water, is circulated. I am aware that it has been proposed heretofore to equip blast furnaces with water tural features of the water jackets for various purposes but so far as I know there has been suggested no successful solution of the problem herein dealt with. 1With the above mentioned objects in view, my invention resides in certain novel strucjacket and in the water circulating system.

In the accompanying drawings I have illustrated al constructional embodiment of my invention, Fig. 1 being a vertical central sectional view of a blast furnace equipped with my improvements, and Fig. 2 a partial view in elevation of the same on a larger scale.

As shown in the drawings, the hearth and bosli portions of the furnace, and part of the stack, are of usual construction, comprising a metallic shell 4 and a refractory lining 2, both apertured for insertion of twyers 6. Attlie top is the usual charging bell provided with valves 8 and l0. It is thought that further description of the parts thus far mentioned is 'unnecessary as my invention is not concerned with them and they may be of any approved construction.

The refractory lining 2 is not carried to the top of the stack but terminates below the level where it would be bombarded by incoming ore and coke; and below the region wherein the greatest fluctuations of temperature occur. These temperature fluctuations, ranging from 4250o F. or even lower, to 900 F. or above are caused, on the one hand, by an abnormal passage of hot gases through relatively pervious parts of the charge, and on the other hand, by incoming charges of cold ore, coke, etc. The region of greatest temperature fluctuations is in the neighborhood of the top of the charge, which does not remain at a constant level, but moves u -or down, a distance of several feet, as a resh charge is introduced or molten pig iron is drawn o, respectively. In my judgment, an interval of 12 to 14 feet between the upper rim of the refractory lining and the charging bell will be an ample allowance for variations in the height of the charge.

, Between the char 'ng bell and the top of shell 4 and lining 2 interpose my improved top section of stack comprising a double walled cylinder having an outer wall 12 and an inner wall 11, preferably of steel, and forming a water circulating annular chamber 14. The inner Wall 11, is preferably corrugated, as shown, to strengthen it against the bombardment of incoming ore, etc. y

In order to compensate for unequal vertical expansion of the inner and outer surfaces of lining 2, of the shell 4 relative to the lining, and of the inner and outer walls 11, 12, I provide a novel expansion joint comprising a flange 30, integral with or rigidly secured to the rim of shell 4, and a flange 31 similarly united to cylinder 12. As shown, flanges 30 and 31 are angularly disposed to one another, contacting at their outer edges and diverging inwardly to leave a space, which is filled With a compressible packing 32, of asbestos or the like. IVhen cold, the oint will be as shown; when the furnace is being operated, the inner surface of lining 2 and inner Wall 11 of the cylinder will expand more than shell 4 and wall 12, thus closing the gap between flanges 30 and 31.

Referring now to the water circulating system, this comprises a drum reservoir 2O and pipes 16 and 18, connecting the drum to the bottom and top respectively of the annular chamber 14. The reservoir 20 is provided with a water-supply pipe 22 having a valve 24; and a blow-ofi:l 26 of any suitable construction. Circulation of the water will be continuously effected by gravity, the hotter water rising in the chamber 14 and through the pipe 18, while the cooler water will descend through pipe 16. It is contemplated that the temperature of the water shall be maintained close to the boiling point. Any steam generated in chamber 14 will be partially condensed in drum 20, the excess passing out through blow-off 26. Sufficient water is admitted from time to time to supply the loss. By maintaining the water near the boiling temperature, in an arrangement such as described, a maximum cooling effect is obtained with a minimum consumption of water, and more important. the rapidity with which heat will be absorbed from the furnace is greatly enhanced. On the one hand, a sudden rise in temperature of the furnace wall will cause evolution of steam in the chamber 14 and the latent heat-of vaporization will be taken mainly from the furnace wall. On the otherl hand, chamber 14 being unobstructedv from top to bottom and annularly, the water can circulate rapidly and promptly reach the point of highest temperature in ample quantities. Any steam generated will rise freely to the top of chamber 14 and pass off through pipe 18 without trapping and carrying off a lar e quantity of water.

n addition to serving as a cooling device, my improved top section tends also to resist change of temperature downward, as when a fresh charge of cold ore and coke 1s 1ntro duced. When this occurs a transfer of heat will take place, from the hot Water in chamber 14 to the fresh charge. The amount of heat transferred will be drawn from all parts of' the water system and also from the interior of the furnace adjacent the lower part of tlh chamber 14, at which level the charge is I claim:

1. In a blast furnace having an inner lining of refractory material thereon, a top shaft section comprising a double-walled metallic cylinder in combination with means for supplying a cooling medium thereto and an expansion joint betweensaid top shaft section and the upper end of said lining of refractory material.

2. In a blast furnace having the lower portion of its wall formed of refractory material, a top shaft section forming the charging inlet to said furnace and contiguous to the chamber therein and comprising concentric metallic cylinders forming an annular water jacket unobstructed from top to bottom and annularly, in combination with means for maintaining water in said packet under pressure to raise its boiling point and means for effecting thermosyphonic circulation of hot Water between said means and said jacket.

3. In a blast furnace having the lower portion of its wall formed of refractory-material, a top shaft section forming the charging inlet to said furnace and contiguous to the chamber therein and comprising concentric metallic cylinders forming an annular chamber unobstructed from top to bottom and anularly, in combination with a reservoir disposed at an elevation above the annular chamber, independent connections from below the water level in said reservoir to the top and to the ybottom of said chamber, and a blow ofi for the notwithstanding the shocks and stresses to which it is subjected during charging operations, in combination with means for supplying a cooling medium to said chamber.

The foregoing specification signed at Cologne, Germany, this 10th day of August,

HEINRICH KOPPERS.

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