US2082280A - Tuyere - Google Patents

Description

a. FOX irr AL June 1, 1937.

TUYERE Filed May 1, 1955' INVENTORS I GORDON FUX. I BY WEN/ZEICE.

- A ORNEY. I

Patented June 1, 1937 UNITED STATES PATENT QFFICE TUYERE Application May 1, 1935, Serial No. 19,138

11 Claims.

The present invention relates to improvements in tuyres,

More particularly the present'invention relates to tuyres such as are used in blast furnaces, which tuyres conduct into a furnace hot air at a high temperature, which may range from 1000 to 1600 degrees F. Such a tuyere is subjected to radiation from the furnace at a temperature of approximately 3000 degrees F. It has been proposed to provide the nose of a tuyere with a refractory substance, this refractory substance being disposed circumferentially of the tuyre and being retained between inner and outer retaining walls at the nose of the tuyere. These walls become very hot in service, for the reason that there is no water cooling immediately adjacent to these walls and they conduct the heat back to the water cooling chamber only with a considerable temperature gradient. A certain amount of melting and withering away of these walls probably occurs at their extremities, the tuyere gradually becoming foreshortened. This foreshortening has two bad effects: first, that the protecting portion of the nose is gradually lost, and, second, that the dimensions of the tuyere change and the blast distribution in the furnace is afiected.

The refractory protection for the nose as heretofore used attains a very high temperature,

probably exceeding 2000 degrees F. in certain portions thereof. Because the refractory reaches so high a temperature, it can be rather easily melted and washed out, and furthermore it can be readily attacked chemically by the slag, inasmuch as chemical reaction is more virulent at high temperatures.

An 'object of the present invention is to provide a tuyere having refractory protective means in the nose region thereof which tuyere will minimize absorption of heat from the furnace by the tuyere.

As a corollary to the object immediately above recited, it is a further object to provide a tuyere presenting as much refractory surface as possible in the nose region of the tuyere, for one or both of two purposes: (1) to protect the copper of the tuyere against contact with molten metal within the furnace, and (2) to shade the copper of the tuyere against radiant heat from the furnace. I

A further object is to subdivide the refractory protecting material and to support it at frequent intervals with copper retaining walls which act both as supports and as cooling members.

A further object is to locate the refractory protecting material in such manner that in case of hot metal contact, said but metal contacts the copper ribs only on their narrow edges.

A further object is to locate the refractory protecting material in such manner that in case of hot metal contact, said hot metal is subdivided into thin divisions which can be more readily combated.

A further object is to protect the portions of the tuyere subjected to the greatest punishment. As corollaries to the objects immediately above recited, a further object is to provide a tuyere having protective refractory material so disposed as to reduce the absorption of heat by the tuyere through radiation from the furnace,

andto provide a tuyere having protective refractory material so disposed that said refractory material is prevented from attaining excessive temperatures by providing heat passages of metal for carrying heat units from said refractory material to the water-cooled portions of the tuyere.

A further object is to provide a tuyre having a nose which will absorb a minimum of heat from a furnace, this result being accomplished due to the low emissivity of the surface of the tuyere presented to the heat within the furnace.

A further object is to combine a heavy nose wall with means for minimizing the temperature of the metal in that nose wall.

Further objects will appear as the description proceeds.

Referring to the drawing Figure 1 is an elevational view, partly in section, illustrating one embodiment of the present invention;

Figure 2 is a sectional view taken along the planes indicated by the arrows 2-2 of Figure 1;

Figure 3 is a fragmentary sectional view illustrating a modification of the structure shown in Figure 1; and

Figure 4 is a fragmentary end view of the structure shown in Figure 3.

Referring first to the construction illustrated in Figures 1 and 2, a water-cooled tuyere is illustrated having the rear wall Hi, the inner side wall H, the outer side wall l2 and the. nose wall I3. Said walls provide an annular chamber for the reception of circulating cooling medium such as water, which chamber is indicated by the numeral H. The numerals [5-15 indicate openings in the rear wall It), one of which openings may be a water inlet and the other of which openings may be a water outlet. A partition wall l6 separates one of the openings l from the other of said openings 5 and extends from the rear wall It to the nose wall It, whereby cooling water is caused to pass in a. series path from inlet to outlet. In order to perform its cooling functions efficiently, the circulating water should travel at high velocity, particularly through the nose portion of the tuyere. Any preferred means for accomplishing this purpose may be utilized. It is at present preferred to utilize the construction illustrated and described in the-patent to Fox to a plane normal to said axis. The bottoms of 26 said recesses "-41 are preferably located in the surface of a frustum of a cone coaxially disposed relative to the tuyere. The recesses ll-ll are filled. with refractory material, indicated by the numeral It. The material of the refrac- -30 tory It may be chosen as desired. Many materials suitable for the purpose are available on the market, such for example as carbon, silicon carbide, carborundum, orgraphite. Other materials suitable for the p rp e are fire clay, 8 bauxite, magnesite, chromite. and blast furnace slag. A number of materials which may be chosen are recited in the United States patent to Beaten No. 1,517,185. The refractory material may be preformed, if. desired, and cast 40 within the ribs. Ila-"a when the tuyere is cast, or the refractory may be packed in like sand and hardened after the tuyere has been cast. The large area of contact between the refractory and the ribs Ila-Ila is sufficient 4.5 under normal conditions to hold the refractory in place. To provide this large area of contact, the recesses II-l I are narrow relative to their depth, whereby the sections of refractory material in said recesses are presented edge on 50 to the exterior of the tuyere, thereby minimizing any tendency of such sections of refractory material to become loose and come out. It is perfectly feasible to supplement the effect of this area by roughening the sides of the ribs Ilm-l'la by means of a chisel or the like. As will be pointed out hereinafter, the material of the refractory It should preferably be so chosen that its emissivity is low. It is possible and practicable to select a refractory having a low value of emissivity, an example of such material being alumina.

In the construction illustrated in Figures 1 and 2, the recesses IT-II do not intersect the throat of the tuyre. According to this construction the segments of refractory material It do not contact with the throat.

According to the'construction illustrated in Figure 4, however, the recesses l! are so disposed that the bottoms thereof intersect the throat 7 Not only is the face of the nose protected, but

of the tuyere, whereby a portion of said throat the side of the tuyre at the nose region is also protected.

The refractory segments lt-IB are closely interspersed with copper retaining walls which restrict the temperature attained by the refractory segments and thus prevent or minimize deterioration or loss of said refractory segments.

The radial copper retaining walls between the refractory segments are exposed to radiation on their edges only, whereby to restrict the temperature attained by said retaining walls. The construction illustrated and described has the inherent advantage that it presents much more refractory surface in the nose region than has been possible in constructions heretofore known, and theexposure of vulnerable copper is correspondingly reduced. It is unavoidable that in the case of attack by hot metal there is a tendency for the radial copper segmental walls between the refractory segements lt-lt to be melted away. However, said refractory segments remain and divide up the molten iron attacking the nose portion of the tuyere into extended finlike portions entering the crevices between said refractory segments. Such relatively thin streams of molten iron are more easily cooled by the substantial mass of relatively cool copper behind the refractory segments and ahead of the water chamber II. It is quite probable, further, that after some of the radial copper segments between the refractory segments l8 have been melted away by attack of molten iron, the spaces left between the refractory segments will flll up either with iron or with slag.

While the inner side wall or the throat of the embodiment of'the present invention illustrated in Figure 1 is fully exposed to radiation and to absorption of heat from the blast, this portion of the tuyere presents an ample copper section to enable the heat thus absorbed to pass to the water chamber I 4 without a steep temperature gradient.

The absorption of heat by the nose of the tuyere is decreased because of the large amount of refractory in this region. The copper located behind the refractory is shielded by said refractory. This copper in normal operation is cooler than it would be if the entire nosewere of metal. The fact that this mass of copper has a very low normal temperature causes this cop ,per to have greater transient ability to absorb heat in case of hot metal attack.

Moreover, the total absorption of heat by a tuyere embodying the present invention is relatively low because of the relatively large amount of refractory shading.

Referring further to the subject matter of the last two paragraphs, it will be apparent that the present invention provides a tuyere which has very much more refractory surface exposed to the heat of the furnace than has been the case with tuyeres as heretofore known and used. This is of value not alone in protecting the tuyere from hot metal attack, but can be made a valuable attribute in reducing the heat absorption of the tuyere in normal operation.

Most of the heat received by the nose face and outer wall surface in normal operation is due to radiation. One factor in the radiant heat absorption by a surface is the emissivity of the surface. A black body (the emissivity of which may be represented by the numeral 1.0) absorbs all of the heat radiated to it. The

emissivity of an oxidized copper surface is about 0.3 to 0.7, depending upon and varying with its a refractory having a value of emissivity of a magnitude of as low as 0.1, or possibly less.

Such refractory will absorb only about of the heat radiated upon it. In other words, it will absorb about $4; to as much heat as an equivalent area of oxidized copper surface.

Thus, by exposing a relatively large area of refractory surface in the nose region and by using a refractory having low emissivity, it is possible to greatly reduce the normal heat absorption of thenose region of the tuyre. The reduced heat absorption results in cooler copper and cooler refractory in normal operation. Thus the refractory is made to serve a double purpose, first, as a protection against hot metal attack, and, second, as a means to minimize heat absorption by the tuyere.

As indicated above, a preferred form of refractory having low emissivity is Y alumina. Other examples of refractory which may be chosen are magnesia, silica, or zirconia.

The present invention has decided advantages also in those cases where the operator may prefer to omit the refractory segments l8i8, relying upon the action of the furnace in depositing material borne during the furnace operation in the spaces between the ribs Ila-Ha.

Though certain embodiments of the present invention have been described in detail, many modifications will occur to those skilled in the art. It is intended to cover all such modifications that fall within the scope of the appended claims.

What is claimed is 1. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with radial ribs extending at least approximately thereacross and providing between them radial recesses, said recesses being narrow relative to their depth and being filled with refractory material, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

2. In a. tuyre, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs extending at least approximately thereacross and providing between them recesses, said recesses communicating with the front face and the outer surface of said tuyere, said recesses being narrow relative to their depth.

3. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs extending at least approximately thereacross and providing between them recesses, said recesses communicating with the front face and the outer surface of said tuyre, the bottoms of said recesses being outwardly and rearwardly inclined, said recesses being narrow relative to their depth.

4. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the

thereacross and providing between them radial recesses, said recesses being filled with refractory material, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

5. ma tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyre throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs providing between them recesses, said recesses communicating with the front face and the outer surface of said nose wall, said recesses being filled with refractory material, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

6. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs extending at least approximately thereacross and providing between them recesses, said recesses being filled with refractory material of the nature of alumina, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

'7. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyre being provided with ribs providing between them recesses, said recesses being narrow relative to their depth, said recesses communicating with the front face and the outer surface of said nose wall, said recesses being filled with. refractory material of the nature of alumina, the outer surfaces of said ribs and the corresponding surfaces of said refractory ma-- terial between said ribs being the outermost surfaces of said nose wall at the corresponding region of saidnose Wall.

8. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with radial ribs extending at least approximately thereacross and providing between them radial recesses, said recesses being filled with refractory material of low emissivity, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

9. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs providing between them recesses being narrow relative to their depth and said recesses communicating with the front face and the outer surface of said nose wall, said recesses being filled with refractory material of low emissivity, the outer surfaces of said ribs and the corresponding surfaces of said refractory material between said ribs being the outermost surfaces of said nose wall at the corresponding region of said nose wall.

10. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose wall of said tuyere being provided with ribs providing between them recesses, said recesses communicating with the front face and the outer surface of said nose wall, said recesses being filled with refractory material of low emissivity, said recesses being narrow relative to their depth whereby the refractory material in said recesses is presented edge on exteriorly of said tuyere.

11. In a tuyere, in combination, a nose wall, side walls and a rear wall forming a tuyere throat and an annular cooling chamber, the nose

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