US2418654A - Metallurgical apparatus - Google Patents

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April 8, 1947- H. E. McDONNELL 2,418,654

METALLURGICAL APPARATUS Filed Dec. 7, 1945 2 Sheets-Sheet 1 I l0 /8 /7 V Y FUR/ma:

3noentor H E: MC

, April 1947- H. E. MODONNELL ,418,654

IETALLURGICAL APPARATUS Filed Dec. 7, 1943 2 Sheets-Sheet 2 Snoentor H. E. McDOA/A/ELL (Itto g Patented Apr. 8, 1947 UNITED STATES- PATENT OFFICE IVIETALLURGICAL APPARATUS Harry E. McDonnell, Steubenv'ille, Ohio Application December '7, 1943, Serial No. 513,271 a (Cl. ace-19) Claims. 1

The present invention relates to the maintenance of uniform conditions in metallurgical furnaces. More specifically, the present invention relates to an improved apparatus for sup- The invention is especially suited to blast.

furnace operations although its application to other metallurgical furnaces will be obvious. In

blast furnace operation an oxygen-containing gas, at present air, is fed at'an elevated temperature to the base of thefurnace to effect combustion of the coke and reduction of the ore. The heated air is introduced adjacent the hearth of the furnace through a plurality of tuyeres symmetrically arranged around the circumference of the lower portion of the furnace. The heated air is supplied to the tuyres from a circular pipe in the form of a manifold, commonly called the'bustle pipe, which in turn receives the heated air at one point from a hot blast main. The air supplied is first compressed and then heated in one of a plurality of stoves. The stoves include a mass of refractory brickwork and operate on the regenerative system, the number of stoves being such that one is supplying heat to the blast while the others are being heated; When the compressed cold air is first admitted to one of the stoves to be heated, the temperature of the blast issuing from the stove is amaximum and as the stove cools off the temperature of the blast reaches a minimum at which time the cold air blast is directed to one of the other stoves. Again the hot blast issuing from this stove is at a maximum temperature and the cycle is repeated. In order to minimize fluctuations intemperature of the hot blast supplied to the furnace, provision is made to supply through aby-pass a portion of the compressed cold. air

. varying in amount so as to maintain the temperature of the hot blast upplied to the furnace at the desired operating temperature. For this purpose the compressed cold air is normally fed into the hot blast main at a point far removed from the furnace so that mixing of the heated air from the stoves with this cold air will be accomplished in some degree. Nevertheless, since space requirements dictate that the stoves must be arof air, the connections from the stoves to the hot blast main are so arranged that the heated air is introduced into the hot blast main at the 'sides thereof. Thus where the streams do not mix properly and the hot blast divides on entering the horizontally disposed bustle pipe, a temperature differential may occur between points on opposite sides of the bustle pipe. This introduces nonuniformity in conditions between tuyeres' adjacent these points. As is well known, any lack of uniformity of conditions inblast furnace operation deleteriously affects overall operation.

This objectionable feature has been recognizedand as a solution therefor, it has been proposed to mix the cold air with the heated air from a stove by introducing the cold air into the base of the combustion well of each stove while it is on blast. This accomplishes the desired mixing, but besides the increased expense required by the necessary conduit connections, the chilling effect, of the cold air introduced. into the combustion well of the stove has a destructive effect. on thebrickwork atthat point.

I have invented apparatus for accomplishing this purpose with a minimum expense and additional structure. The present invention utilizes the hot blast main between the furnace and the stove nearest the furnace as a mixing chamber and by creating turbulence at this point effectively mixes the hot and cold blasts to deliver a resultant stream of hot blast of uniform vention is the provision of an improved apparatus for mixing streams of heated oxygencontaining gas and cold oxygen-containing gas prior to introduction to a metallurgical furnace.

Referring to the drawings which disclose apparatus according to the present invention,

Figure 1 is a plan view, partially diagrammatic,

of a form of the a paratus with the furnace shownin section and parts broken away to illustrate the invention more clearly,

Figure 2 is a view in longitudinal section of part of a hot blast main showing an embodiment of the present invention,

Figure 3 is a view in cross section taken on line 3--3 of Figure 2,

Figure 4 is a view in longitudinal section of part of a hot blast main showing another embodiment of the present invention,

Figure 5 is a view in cross section taken on the line 5-5 of Figure 4,

Figure 6 is a view in longitudinal section of part of a hot blast main showing a further embodiment of the present invention,

Figure 7 is a view in cross section taken on the line l-I of Figure 6,

Figure 8 is a view in longitudinal section of a part of a hot blast main showing a still further embodiment of the present invention, and

Figure 9 is a view in cross section taken on the line 9-9 of Figure 8.

Referring to Figure 1, a furnace wall is indicated at ill, a section being taken through this wall above the tuyeres. A bustle pipe is indicated at H connected to the tuyeres (not shown) by pen stocks i2, I 3, l4 and 15. Additional pen stocks are shown for connection with the remaining tuyeres. This figure being in plan view, the

. hearth of the furnace shows at I6. Connected at one side of the bustle I l is a hot blast main H and connected to the hot blast main by conduit I8, which normally includes a hot blast valve (not shown), is a stove is of any desirable type.

A plurality of additional stoves are connected in like manner to hot blast main l1. At a point on hot blast main l1 beyond the farthest stove there is a connection to a by-pass conduit from the. cold blast main. Since this latter structure is conventional, it has not been shown. Between.

the connection of stove is and hot blast main I! there is a restriction in the hot blast main indicated at 20. The purpose of restriction 20 is to change the pressure and velocity of the air at this point and thereby achieve mixing of the streams of air in the hot blast main, theselating brick 22 in the usual manner has the lining built up to one form of configuration suitable for achieving my purpose. The brickwork is shaped to give projections 23 and 24 spaced from one another along the length of the main to form a throat having its long axis at an angleto that of the hot blast main. These projections each cover half of the interior of the pipe as best seen in Figure 3 and merge with the brickwork by sloping portions 25, 26, 21 and 28. Due to the high velocity of the air through the hot blast main the merging surfaces are necessary to reduce as far as possible erosion of the brick lining. Pro-'- embodiment of restriction 20 is shown. In this modification the brickwork 22 of the hot blast main is shaped to form a helical rib 32 which merges into the internal wall of the hot blast main by means of surfaces 33 and 34. The helical rib 32 merges at its ends into the surface of the internal wall of the hot blast main by tapered sections as indicated at 35 in Figure 7. This embodiment of, the invention operates on the stream of air passing through the hot blast main to impart thereto a rotational movement. Depending upon the velocity of the stream, the peripheral portion thereof will be given a higher degree of rotational movement than the central portion, the relative rotation acting to mix the hot and cold streams forming the components. The modification shown in Figures 8 and 9 discloses a different apparatus for accomplishing the same'purpose as that in Figures 6 and 7. Here a conduit 36 from a stove supplies hot gas to the hot blast main indicated at 31 man arrangement similar to that shown in Figure 1. In this case however, conduit 36 has oil-center connection with the hot blast main 3'! so that the hot stream from the stove enters the cold stream from the by-pass conduit in such a manner that rotation of the resultant stream takes place. This rotation as in the caseof the embodiment shown in Figures 6 and 7 acts to mix the component streams of hot and cold air.

In Figure 2 to 9 inclusive the internal walls of the conduits are shown in elevation, the lines appearing on these surfaces roughly indicating courses of brickwork to give these showings a three dimensional appearance.

In an installation of the invention in a blast furnace with an arrangement similar to that in Figure 1 and using arestriction like that shown in Figures 4 and 5, highly satisfactory results were achieved. In this installation the velocity of the air in the hot blast main varied from about jections 23 and 24 act on the streams of air flowing through the hot blast main to throw the streams together and thus achieve a mixing action.

Referring to-Figure 4, a further modification of the restriction 20 is shown. In this embodiment brickwork 22 is shaped to form a Venturi throat 2-9 merging into the walls of the hot blast main by means of truncated cone surfaces 30, 3|

following the conventional Venturi tube construction. In the case of this embodiment, a mixing of the streams of air in the hot blast main is achieved by means. of the well-known characteristics of the Venturi tube.

Referring to Figures 6 and 7, a still further 90 feet per second to 150 feet per second, depending upon the temperature and volume of the blast. The temperature of the hot blast issuing from the stove was around 1800 F. while the temperature of the cold blast being introduced into the hot blast main from the by-pass conduit was about '200" F. The quantity of cold blast was controlled to give an average temperature around 1200 F. at the bustle pipe, although for operating reasons the temperature at this point is varied from about 900 F. to about 1200 F. The temperature differential at the tuyeres corresponding to pen stocks i3 and I5 shown in Figure -l ranged from 15 to 20 F. with'a maximum of 50 F. when a large amount of cold blast and the stove nearest the furnace were being-used. In a similar installation not utilizing the present invention, the temperature differential at these points'varied from 50 to 150 F. with a maximum around 200 F. where a large amount of cold blast and the stove nearest the furnace werebeing used.

Since emcient. and economical operation of a 'blast furnace calls for 'uniform conditions of the furnace and by producing a difference in the sensible temperature of the air at these points.

By means of a simple modification of existing structure or the incorporation of the simplified structure disclosed herein in a new installation.

an improved structure is achieved with a minimum of expense and no new maintenance problems.

I claim:

1. In a blast furnace having a plurality of tuyeres, a horizontally disposed bustle pipe connected therewith, a stove for supplying a stream of hot gas, and a source for supplying a stream of cold gas, the combination comprising a hot blast main adjacent the stove, connected at one end with the bustle pipe and connected at a point removed therefrom with the source of, cold gas, a stove connection on the side of the hot blast main at a point between the cold gas connection and the bustle pipe connection, a conduit between the stove and the stove connection on the hot blast main for conducting the stream of hot gas from the stove into the hotblast main, internal wall surfaces of refractory material in the hot blast main and the conduit. and a restriction formed by said surfaces in the hot blast main between the bustle pipe connection and the stove connection for mixing the streams of hot and cold gas in the hot blast main.

2. The combination claimed in claim 1, characterized by the fact that the restriction includes a projection of said surfaces into the hot blast main so as to oppose the flow of a substantial portion of the stream of gas therein to change the direction of said portion with respect to the remainder of the stream of gas therein.

3. The combination claimed in claim 1, characterized by the fact that the restriction is in the form of a throat, the axis of which is at an angle to the axis of the hot blast main.

4. The combination claimed in claim 1, characterized by the fact that the restriction is in the form of a Venturi throat.

5. The combination claimed in claim 1, characterized by the fact that the restriction is in the form of a helical rib.

HARRY E. McDONNELL.

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

UNITED STATES PATENTS

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