US2619344A - Stock-feeding hopper for blast furnaces - Google Patents

Description

Nov., 25, 1952 w. H. MuRscH 2,619,344

STOCK-FEEDING HOPPER FOR BLAST-FURNACES Filed July l2, 1949 2 Sl'lEETS--SI-IEET 1 Nov. 25, E952 w. H. MURscl-l sfrocx-FBEDING HOPPER FOR BLAsT-FuRNAcEs 2 SHEETS-SHEET 2 Filed July l2 1949 F IE.. 4f.

Patented Nov. Z5, 1952 UNITED STATES PATENT OFFICE STOCK-FEEDING HOPPER FOR BLAST FURNACES William H. Mursch, Pittsburgh, Pa., assignor to United States Steel Company, a corporation of New Jersey 4 Claims.

This invention relates to an improved apparatus for feeding stock into a blast-furnace and, more particularly, to a novel hopper adapted to be mounted on the furnace top for maintaining a column of the stock being charged from a skiphoist, conveyor or like charging means, so that it feeds itself into the stack as the stock line falls.

The double-bell-and-hopper mechanism which has been installed in the tops of blast-furnaces in recent years is complicated, expensive and difficult to maintain, to say nothing of numerous other disadvantages. It is accordingly the object of my invention to provide a simple stock-feeding apparatus without moving parts which is relatively cheap to construct and requires little or no maintenance, as well as a method for maintaining a column of stock for more or less continuous flow into the furnace stack. Other objects and advantages of the invention will become4 apparent from the following detailed description or will be specifically pointed out hereinafter.

I maintain a column of stock in the top of the stack, extending thereabove and resting on the furnace burden, of sufficient height to prevent the escape of a substantial quantity of furnace gases. As stock descends from the feeding column into the stack by gravity, I replenish the column from the top. I also maintain a suction around the girth of the column about midway of its height to carry away any small amount of air and furnace gases which may seep through the stock in the column. I distribute the stock flowing from the hopper into the furnace around the circumference thereof and provide passages for the escape of gases from the space below the column to the usual gas uptakes.

In a preferred embodiment, my improved stock-feeding hopper comprises a stationary tubular body having a closed top provided with' charging ports. These ports are fitted with removable covers or doors. The hopper is open at the bottom and is so mounted on the furnace stack that its lower end depends thereinto. A spreader cone is fixed in the bottom of the hopper so as to leave an open space between it and the hopper entirely around the circumference of the latter. An annular exhaust chamber surrounds the hopper about midway of its height. A suction ring communicating therewith is connected to an exhaust fan for taking away air and furnace gases seeping through the stock in the hopper under normal operating conditions.

A complete understanding of the invention may be obtained from the 'following detailed descrip.

tion and explanation which refer to the accompanying drawings illustrating apparatus for carrying out the present preferred practice. In the drawings,

Figure 1 is a diagrammatic elevation of the top of a blast-furnace having my improved hopper incorporated therein;

Figure 2 is a partial vertical section through the axis of the furnace in a, plane parallel to that on which Figure l is projected;

Figure 3 is a partial elevation of the top of the hopper such as would be seen by viewing Figure 2 from the left;

Figure 4 is a partial section similar to Figure 2 showing a modified charging port; and

Figure 5 is a further partial section similar to Figure 2 showing a modified form of spreader cone.

Referring now in detail to the drawings and, for the present, particularly to Figure 1, the upper portion of the stack of a blast-furnace, indicated at I0, is surmounted by my improved stockfeeding means or hopper II Uptakes I2 extending upwardly from the furnace top are connected by a junction pipe I3 from which a downcomer I4 leads to a dust-catcher I5.

The hopper II is shown in detail in Figures 2 and 3. It comprises coaxial tubular upper and lower portions I6 and Il, each of which is substantially a right-circular cylinder. The upper -cylinder IB is positioned above the top of the furnace while the lower cylinder I1 depends thereinto. The hopper and associated parts about to be described are conveniently fabricated from steel plate. The upper` cylinder I6 has a frusto-conical skirt I8 adjacent the lower end thereof adapted to rest on and be secured to the top of the shell I9 of the furnace. The lower cylinder Il' is spaced from the upper cylinder, being suspended on a frusto-conical wall 20 extending inwardly and downwardly from the skirt I8.

The upper cylinder I6 of the hopper has a top wall 2l provided with charging ports 22 each adapted to receive stock from a charging skip 23. Covers 24 for the ports 22 are mounted on pivoted levers 25 to which operating cables 26 are attached. The covers are normally held in open position so that the hopper is open to the atmosphere through the ports 22. Stock elevated from storage bins by the skips 23 is charged into the ports 22 alternately until a column of stock insides of the upper portion of the hopper prevent segregation of the material charged. A stockline recorder 30 rests on the top of the column 21 in the hopper.

As the burden 28 descends in the normal operation of the furnace, stock flows from the hopper into the furnace proper. A spreader cone 3l is spaced below the bottom of the lower cylinder I1 with its vertex extending upwardly thereinto.

Vent connections 32 extending from the interior.

of the cone through the wall ofthe lower portion of the hopper suspend the former on the latter and also permit the escape of any gases a-ccumulating below the cone through the .uptakes I 2. As will be evident from Figure 2, the downward flow of stock from the hopper through the space ybetween the lower edge of portion I1 thereof` and the cone 3| tends to form a void 33 below the latter as a result of the angle of repose of .the material composing the charge.

The hopper I I is of sufficient height so that the column- 21 prevents the escape of substantial quantities of furnace gases under the slight positive pressure in the top of the furnace. This pressure amounts to only a few feet of water and, despite the granular character of .the stock, a column thereof capable of preventing objectionable loss of gas may be maintained within a hopper having a reasonable over-all height, say ten Because of the granular character of the feet. stock, there will inevitably be a small amount of gas seepage upwardly through the column confined in the hopper. I accordingly utilize the circumferential duct 34 defined by the upper portionof the frusto-conical skirt I8, the lower end Y of the wall of the upper cylinder I6 and the frusto-conica-l wall 20 at the upper end of lower cylinder I1 as an exhaust manifold. A suction ring 35 extending around the hopper at about the level of the ymanifold is connected thereto by circumferentially spaced outlet ports 36. As shown .in Figure l, the ring 35 is connected by pipe-36a .to asuction fan 31. Ableeder pipe38, the lower end of which communicates with the downcomer I4, theupperend being The fandischarg-es into a open to the atmosphere. 4Valves 39 in `the pipe 38-on opposite sides of the intersection of the fan-discharge pipe, permit gases withdrawn from `the hopper to bedischarge-d into the atmosphere .or into the downcomer at will. The suction maintained by the fan inthe exhaustv manifold togetherl with atmospheric pressure on top'of the column in the hopper will cause a certain amount of air tobe drawn through the stock in the upper 4cylinder I6 of the hopper, along with the furnace gases which seep upwardly through the stock in vthe lower. cylinder I1.

. entlyv from the lever 25, as shown, in order to facilitate holding the cover in .the illustrated position.

Figure 5 illustrates a modified form of spreader cone. lower frusto-conical portion 43, an upper conical portion 44 and a cylindrical intermediate portion ,Y 45.- Radial vent connections 46 .extend horizontally from theocylindrical portion 45 through A vthe wall of the lowerportion, I 1 of the hopper.

This cone, designated 42, includes a` It will be evident from the foregoing that the hopper of my invention has numerous advantages over the conventional double-bell-and-hopper which have been installed in the tops of blast furnaces heretofore. In the first place, the apparatus involves no moving parts but the coveroperating levers. These are actuated only when the furnace is banked or after a serious slip but the ports normally remain open. The cost of my improved hopper is much less than that of -conventional equipment. Little or no maintenance y is required. In addition, the operation of the furnace is improved, fewer slips and smaller pressurefiuctuations are experienced because of the relatively continuous flow of material from the hopper'into the furnace. The improved hopper,

, furthermore, is well-adapted to conveyor charging.

,My invention has the advantage that there is n-o leakage of furnace gases as is experienced with'the double-bell-and-hopper when the bells .become warped. vFlue dust is minimized because there is no sudden descent'of material, as when dthelarge bell of the conventional structure is lowered, but only a slow substantially continul ous downward flow thereof. This also reduces wear. on `the lining of the furnace adjacent the thereof presents no serious problem.

The absence of gas-sealing surfaces eliminates The usual revolving distributor is maintaining the gas-sealing surfaces thereof. The entire apparatus takes up, no more space than the conventional. furnace top including the vtwo bells an-d the usual revolving distributor.

I claim: l. In ablast-furnace, a stack, a hopper on the top of the stack adapted to. hold a column of stock,.said 'hopper comprising coaxial upper and lower tubular portions spaced apart vertically with a circumferential .clear spacel between the bottom of the upper lportion and the top of the lower portion, the lower. portion depending into .'.thestack and the upper portion extending upwardlyabove. the stack, saidfstack` having a gas l. offtake-adjacent the topat a level intermediate the ends ofthe lower portion, a spreader cone spaced belowthe lower end of the lower portion andlfixedly vmounted thereon, pipe connections extending from the cone lto the wall of the lower portion, effective to vent to `said offtake any gases collecting under said cone,` means defining an outlet passage circumferentiallyof said tubular portions vand communicating with the clear ing a suction pipe ring around one of the tubular portions, and said passage having ports comvmunicating with said ring.

l 3, In a blast-furnace, a stack, a hopper on the top of the stack, said hopper comprising a lower tubular portion, extending downwardly into the stack and an upper tubular portion upstanding p above the top of the stack, said stack having a gas offtake adjacent the top at a level intermediate the endsof the lower portions, saidl portions being Adisposed coaxially in vertically spacedrefor disposal of any gases seeping through said 1o Number column, and a frusto-conical skirt extending downwardly from the upper portion and bearing on top of the stack, said exhaust ports extending through said skirt.

4. A blast-furnace as dened by claim 3 char- 15 acterized by an inverted frusto-conical wall extending downwardly and inwardly from said skirt and suspending the lower portion, said wall and skirt forming an annular chamber surrounding the hopper yadjacent said space.

WILLIAM H. MURSCH.

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

UNITED STATES PATENTS Name Date 1,743,394 Rhoades Jan. 14, 1930 2,083,711 Huyck 'June 15, 1937 2,490,828 Newton Dec. 3, 1949 FOREIGN PATENTS Number Country Date 109,264 Great Britain Feb. 21, 1918 377,896 Germany June 29, 1926 433,657 France Nov. 3, 1911

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