US3830481A

US3830481A - Refractory lining in a vertical shaft furnace

Info

Publication number: US3830481A
Application number: US00330340A
Authority: US
Inventors: E Dominguez; J Lynn; G Sundy
Original assignee: Bethlehem Steel Corp
Current assignee: Bethlehem Steel Corp
Priority date: 1973-02-07
Filing date: 1973-02-07
Publication date: 1974-08-20
Anticipated expiration: 1991-08-20

Abstract

A multipart refractory assembly comprising a left hand section comprised of two mated parts and a right hand section comprised of two mated parts, which sections when laid-up contiguously form a portion of the bustle of a vertical shaft furnace and an inlet passage extending from the bustle to the interior of the vertical shaft furnace. The left hand section is made of two refractory shapes which are placed one atop the other and are locked in place by tongue and groove means. The upper part has six faces. Five of the faces are plane surfaces. The bottom face is provided with a tongue in the rear portion thereof, a groove in the forward portion thereof and a curvilinear portion connecting the rear portion and the forward portion. The lower part also has six faces. Five of the faces are plane surfaces. The upper face is provided with a tongue in the forward portion thereof, a groove in the rear portion thereof and a curvilinear surface connecting the forward portion and rear portion. A side face of the lower part is provided with a groove extending from the curvilinear surface to the forward face thereof. When the bottom face of the upper part and the top face of the lower part are placed together the tongue and groove in the upper part mate with the groove and tongue in the lower part to lock the parts together. The curvilinear surfaces in the parts form a continuous surface which is generally elliptical in shape. The right hand section is a mirror image of the left hand section. When the left hand and right hand sections are laid-up contiguously, the generally semi-circular grooves in the side faces form a generally circular inlet passage extending from the generally elliptical surface of the forward face of the assembly. A generally elliptical opening or port is formed in the front face of the assembly. The upper parts of each section are identical. Therefore by mating two upper parts a section which does not contain an inlet passage or a port can be formed. Laying two sections of these parts contiguously forms a four-piece refractory assembly which does not have an inlet passage extending from the elliptical surface to a front face of the refractory assembly. The use of the two four-piece refractory assemblies described above in laying-up the refractory lining of a vertical shaft furnace makes it possible to assure uniform distribution of hot combustion gases into a pellet bed in the vertical shaft furnace to thereby distribute heat uniformly into the pellet bed.

Description

United States Patent [191 Dominguez et al.

[451 Aug. 20, 1974 1 1 REFRACTORY LINING IN A VERTICAL SHAFT FURNACE [75] Inventors: Ezekiel C. Dominguez, Bethlehem;

John D. Lynn, Center Valley; George J. Sundy, Bethlehem, all of Pa.

[73] Assignee: Bethlehem Steel Corporation,

Bethlehem, Pa.

22 Filed: Feb. 7, 1973 211 Appl. No.: 330,340

Primary Examiner-Gerald A. Dost Attorney, Agent, or Firm-Joseph J. OKeefe; Charles A. Wilkinson; John S. Simitz [57] ABSTRACT A multipart refractory assembly comprising a left hand section comprised of two mated parts and a right hand section comprised of two mated parts, which sections when laid-up contiguously form a portion of the bustle of a vertical shaft furnace and an inlet passage extending from the bustle to the interior of the vertical shaft furnace. The left hand section is made of two refractory shapes which are placed one atop the other and are locked in place by tongue and groove means. The upper part has six faces. Five of the faces are plane surfaces. The bottom face is provided with a tongue in the rear portion thereof, a groove in the forward portion thereof and a curvilinear portion connecting the rear portion and the forward portion. The lower part also has six faces. Five of the faces are plane surfaces. The upper face is provided with a tongue in the forward portion thereof, a groove in the rear portion thereof and a curvilinear surface connecting the forward portion and rear portion. A side face of the lower part is provided with a groove extending from the curvilinear surface to the forward face thereof. When the bottom face of the upper part and the top face of the lower part are placed together the tongue and groove in the upper part mate with the groove and tongue in the lower part to lock the parts together. The curvilinear surfaces in the parts form a continuous surface which is generally elliptical in shape.

The right hand section is a mirror image of the left hand section. When the left hand and right hand sections are laid-up contiguously, the generally semi-circular grooves in the side faces form a generally circular inlet passage extending from the generally elliptical surface of the forward face of the assembly. A generally elliptical opening or port is formed in the front face of the assembly.

The upper parts of each section are identical. Therefore by mating two upper parts a section which does not contain an inlet passage or a port can be formed. Laying two sections of these parts contiguously forms a four-piece refractory assembly which does not have an inlet passage extending from the elliptical surface to a front face of the refractory assembly. The use of the two four-piece refractory assemblies described above in laying-up the refractory lining of a vertical shaft furnace makes it possible to assure uniform distribution of hot combustion gases into a pellet bed in the vertical shaft furnace to thereby distribute heat uniformly into the pellet bed.

10 Claims, 6 Drawing Figures I REFRACTORY LINING IN A VERTICAL SHAFT FURNACE BACKGROUND OF THE INVENTION This invention is directed to vertical shaft type furnaces lined with refractory shapes and more particularly to a refractory assembly formed by laying-up a plurality of refractory shapes contiguously to form a portion of the bustle and an inlet passage and an attendant port in the refractory lining in the upper stove of a vertical shaft furnace whereby hot combustion gases are introduced into the upper stove of the furnace.

Balled iron ores and/or concentrates are frequently heated in a vertical shaft furnace to elevatedtemperatures and are thereby heat hardened to form pellets which are suitable for charging into metallurgical furnaces, such as blast furnaces, electric furnaces and the like. The balled iron ores and/or concentrates are charged into the top section, called the upper stove, of the vertical shaft furnace. Hot combustion gases generated in external combustion chambers are introduced into the lower portion of the upper stove and pass upwardly through the balled iron ores and/or'concentrates to thereby heat the balls to a temperature sufficiently high to harden the balls and form pellets therefrom. The pellets move downwardly to a lower stove of the vertical shaft furnace where the pellets are partially cooled by atmospheric air passing upwardly through the vertical shaft furnace. The amount of air drawn into the lower stove and passing upwardly through the pellets is such that the air is heated to a temperature about equal to the temperature of the hot combustion gases. The partially cooled pellets pass out of the vertical shaft furnace to a separate cooler where additional atmospheric air is blown upwardly through the pellets, which are thereby cooled to a temperature sufficiently low to allow handling on belt conveyors. The heat absorbed by the cooling air is transferred through a heat exchanger to fresh atmospheric air which is preheated and fed into the external combustion chambers. Fuel oil or natural gas is burned in the external combustion chambers to generate the hot combustion gases which are introduced into the upper stove to harden the balled iron ores and/or concentrates. The hot combustion gases pass from the external combustion chambers through a refractory lined flue which connects the external combustion chambers to the vertical shaft furnace, to the bustle of the vertical shaft furnace. A series of spaced inlet passages and ports, which extend from the bustle to the lower portion of the upper stove of the vertical shaft furnace, are provided to introduce the hot combustion gases into the lower portion of the upper stove of the vertical shaft furnace. The hot combustion gases pass upwardly through the balled iron ores and/or concentrates to heat the balls to temperatures of 2,100 to 2,500 F. to harden the balls and form pellets.

The bustle of the vertical shaft furnace is formed in the refractory lining of the vertical shaft furnace and generally comprises a passage formed by the refractory shapes in the refractory lining. The inlet passages and attendant ports through which the hot combustion gases are introduced into the upper stove of the vertical shaft furnace are formed either in the refractory shapes used to lay-up the refractory lining or are formed by spaces left between the refractory shapes when layingup the refractory lining.

Unfortunately, the refractory lining is conventionally laid-up in the vertical shaft furnace in a manner such that the bustle is located outside or beyond the outer vertical refractory wall of the vertical shaft furnace. Consequently, when the refractory lining which forms the bustle is heated during furnace operation, the refractory lining expands upwardly creating a shear plane in line with the steel shell of the vertical shaft furnace. The refractory shapes which form the top of the bustle tend to crack at or near the center of the span because of the shear forces produced by the thermal expansion. The refractory shapes in the refractory lining above the bustle also tend to crack or separate from each other. These refractory shapes become loose and are tilted toward the interior of the vertical shaft furnace because of the pressure exerted upon the inside face of the tile by the heated combustion gases.

The hot combustion gases are fed under pressure into the furnace. Any cracks in the refractory lining allow leakage of the gases from the bustle into the interior of the vertical shaft furnace without passing through the spaced inlet passages and attendant ports, thereby upsetting the distribution of the hot' combustion gases passing through the inlet passages into the vertical shaft furnace and resulting in a non-uniform distribution of the hot combustion gases in the bed of balled iron ores and/or concentrates in the vertical furnace. As a consequence, non-uniform heating of the balled iron ores and/or concentrates occurs. Increasing the pressure of the hot combustion gases in the bustle in an attempt to correct the non-uniform heating problem actually aggravates the situation and causes further excessive gas leakage. The increased pressure of the hot combustion gases causes the loose and the cracked refractory shapes forming the bustle to tilt inwardly into the vertical shaft furnace. The tilt of the refractory shapes often becomes quite severe. Pellets also collect around the attendant ports of the inlet passages, resulting in the fusing of the pellets and clogging of the ports and inlet passages.

The vertical shaft furnace must frequently be taken out of production to repair the refractory lining. As a result, loss of production time is excessive. If the refractory lining is not repaired the back-pressure from the hot combustion gases needed for pelletizing the balled iron ores and/or concentrates causes the bustle area to be pushed out-of-alignment, further increasing the cracking problem. If the pressure of the incoming hot combustion gases is reduced to alleviate the cracking problem, non-uniform heating of the pellets also occurs, thereby causing variations in pellet quality and reduced production because of inefficient and ineffective heating of the balled iron ore and/or concentrates in the upper stove.

It is therefore an object of this invention to provide a bustle and attendant inlet passages and ports whereby problems related to thermic expansion are eliminated.

It is a further object of this invention to provide a refractory assembly comprising a portion of the bustle and attendant inlet passages and ports for a vertical shaft furnace which will allow the use of higher back pressures to introduce hot combustion gases required for pelletization into the shaft of the furnace.

It is another object of this invention to provide a refractory assembly comprising a portion of the bustle and attendant inlet passages and ports which will result SUMMARY OF THE INVENTION The improved construction of the refractory lining of I a vertical shaft furnace according to the present invention includes the use of a plurality of novel refractory assemblies in the bustle and inlet passage area of the refractory lining. The novel refractory assembly includes a plurality of refractory shapes which form a portion of the bustle and vertical wall in the upper stove of the shaft furnace. An inlet passage extending from the bustle to the interior of the vertical shaft furnace and culminating in a port is incorporated into the assembly. The inlet passage is inclined downwardly at an angle from the bustle to a plane parallel to the base of the assembly.

DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional end view of prior art bustle and attendant inlet passages and ports in a vertical shaft furnace.

FIG. 2 is a cross-sectional end view of the improved refractory lining of the invention in which a plurality of the refractory assemblies are incorporated in the refractory lining.

FIG. 3 is an isometric view of the refractory assembly of the invention.

FIG. 4 is an exploded isometric view of the preferred quadripartite refractory assembly of the invention.

FIG. 5 is an isometric view of a variation of the refractory assembly of the invention.

FIG. 6 is an exploded isometric view of one variation of the bustle and inlet passage refractory assembly of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the figures, FIG. 1 is a cross-sectional view of the end wall of a prior art vertical shaft pelletizing furnace including an upper stove and a lower stove, showing the conventional method of incorporating a bustle, attendant inlet passages and ports in the refractory lining at the bottom of the upper stove of the vertical shaft furnace. The vertical shaft pelletizing furnace, shown generally at 10, comprisesa steel shell 11 and a refractory liningv 12, comprising various refractory shapes laid-up inside the steel shell 11. The refractory shapes are usually made from alumina and aluminasilica raw materials. The refractory lining I2 is laid-up to form a generally rectangular space or opening 13, called a bustle, which extends around the four sides of the vertical shaft furnace. A refractory cover tile 19 forms the top of the bustle 13. A refractory port tile 14 forms the front wall 14a of the bustle 13. The back wall 14b and bottom 14c of the bustle 13 are formed by the refractory shapes laid-up to form the refractory lining 12 of the vertical shaft furnace 10. An inlet passage 15 is provided in the refractory port tile 14 to allow hot combustion gases, which are required to harden the balled iron ores and/or concentrates to thereby form pellets, to pass from the bustle 13 into the interior 16 of the vertical shaft furnace 10. The inlet passage 15 is directed substantially diagonally downwardly from the front wall 14a of the bustle 13 to the interior 16 of the vertical shaft furnace 10. The downwardly directed position of the opening 15a of the inlet passage 15 prevents ingress of the hot pellets into the inlet passage 15 and prevents clogging of the port 15a.

A straight line projection (dotted line) of the steel shell 11 of the vertical shaft furnace 10 from the upper portion 17 thereof to the lower portion 18 thereof, passes along the front wall of the bustle 13. When the refractory shapes which form the refractory lining 12 in the lower portion 18 of the vertical shaft furnace l0 become heated by hot combustion gases they expand upwardly causing a shear plane to form along the straight line projection of the steel shell 11. The shear stresses created in the refractory lining cause the refractory cover tile 19 to crack at the point of maximum stress which is at or near the center of the refractory cover tile 19. The refractory cover tile 19 also supports a portion of the refractory lining in the upper stove of the vertical shaft furnace. When the refractory cover tile 19 cracks, the support is weakened thereby allowing the refractory shapes which form the refractory lining to shift. The refractory shapes can crack or can part along the line 19a19b. The cracked portion of the refractory lining has a tendency to move toward the interior 16 of the vertical shaft furnace 10. The portion 19c of the refractory lining 12 is literally pushed into the vertical shaft furnace 10 by the pressure of the hot combustion gases in the bustle. The back-pressure of the hot combustion gases in the bustle decreases because of leakage through the cracks l9a-19b in the refractory lining 12, resulting in nonuniform distribution of the hot combustion gases into the bed of balled iron ore and/or concentrates in the vertical shaft furnace 10. The overall uniform quality of the pellets formed under such conditions is poor. Increasing the back pressure of the hot combustion gases in the bustle 13 of the vertical shaft furnace 10 results in tilting the cracked portion 190 of the refractory lining l2 farther into the interior 16 of the vertical shaft furnace 10 and does not improve the non-uniform flow of the hot combustion gases into the pellet bed. Hence, improvement in the uniform quality of the pellets is not achieved even at a considerable increase in fuel consumption.

Theimproved construction of the bustle and inlet passage and attendant port in the refractory lining of a vertical shaft furnace in accordance with the present invention is shown in FIG. 2. To properly compare the improved construction of the invention with prior art construction, identical numbers as used in FIG. I to identify the parts of the vertical shaft furnace will also be used to identify corresponding or identical parts in FIG. 2.

The refractory lining l2 laid-up against the steel shell 11 of the vertical shaft furnace 10 includes a refractory assembly 14 of mated refractory shapes 14d and Me which are laid-up contiguously in the refractory lining 12. The assembly 14 forms a portion of the generally elliptical bustle 13 and includes a generally cylindrical inlet passage 15. Note that the inlet passage 15 extends generally vertically downwardly from the bustle 13 toward the base of the refractory assembly as it extends toward the interior 16 of the vertical shaft furnace 10. The generally elliptical port a of the inlet passage 15 is in line with the inside surface 12a of the refractory lining 12, unlike the port 15a of the inlet passage 15 in the prior art construction. It has been found that the pellets in the pellet bed do not collect nor intrude into the inlet passage 15 through the port 15a of the improved construction of the invention to thereby block the port 15a whereas the prior art construction was susceptible to blockage of the port 15a because of pellet buildup along the inclined portion 12b of the surface 12a of the refractory lining 12. With the new construction of the bustle and inlet passage assembly 14, no cantilever loading is included in the refractory lining 12. In the improved construction, a shear plane is deliberately built into the refractory lining to relieve the shear stresses caused by the thermal expansion of the refractory shapes. The thermal expansion of the refractory shapes which form the refractory lining is distributed more evenly and transmitted more evenly through the bustle and inlet passage assembly, thereby eliminating the problem of cracking and separation of refractory shapes which form the refractory lining above the bustle and inlet passage area of the refractory lining as in the prior art. Although we have shown a row of the refractory assemblies 14 extending across one end wall of the vertical shaft furnace, several of the refractory assemblies can be made in a manner to exclude the inlet passage 15 and port 15a. While we have used the refractory assemblies only in the long walls of the vertical shaft furnace, the refractory assemblies can be used in both the end walls and the long walls of the vertical shaft furnace to provide equal distribution of hot combustion gases within the upper stove of the vertical shaft furnace. The row of refractory assemblies can contain one or any number of inlet passages 15 and ports 15a which are desired or required to produce uniform heating of the balled iron ores and/or concentrates to produce a uniform quality of pellets.

The preferred embodiment of the refractory bustle and inlet passage assembly of the invention is a quadripartite assembly as shown in isometric view, FIG. 3, and exploded isometric view, FIG. 4.

Turning now to FIG. 3, the quadripartite refractory assembly 14 is made of two pairs of mated refractory shapes comprising a left hand section formed by mated upper part 21 and lower part 22 and a'right hand section 23 formed by mated upper part 24 and lower part 25. The left hand section 20 and right hand section 23 are laid-up contiguously in the refractory lining and are opposite hands, or mirror-images, of each other. A generally oval or elliptical opening 13a, which forms a portion of the bustle 13, is formed when the

parts

21, 22, 24 and 25 are assembled as shown. A generally cylindrical inlet passage 15 is formed by the

lower parts

22 and 25 in the manner shown. The inlet passage 15 extends generally diagonally outwardly and downwardly from the bustle 13 to a generally elliptical port 15a, which is the external opening of the inlet passage 15. The

parts

21, 22, 24 and 25 are held in place by

tongues

26 and 27 which fit into grooves 28 and 29 respectively as shown in FIG. 3. The assembly 14 in FIG. 3 is shown with the parts in spaced relationship to each other for clarity only. In actual use the upper and lower parts are mated to form the left hand section and the right hand section which in turn are laid-up contiguously or butted together to form the refractory assembly 14.

Turning now to the exploded isometric view, FIG. 4, the left hand section 20, comprising upper part 21 and lower part 22, and the right hand section 23, comprising upper part 24 and lower part 25, are opposite hand of each other, therefore only the left hand section 20 will be described. It will be noted that

upper parts

21 and 24 are identical and can be substituted for each other in forming the refractory assembly. All the refractory shapes in the refractory assembly 14 have six faces. Five of the faces are plane surfaces while the sixth face comprises two plane surfaces and a curvilinear surface. The left hand section 20 comprises two mated parts, an upper part 21 and a lower part 22. The upper part 21 is generally a parallelepiped and has generally rectangular parallel front and rear faces 37 and 38 respectively and generally rectangular

parallel sides

39 and 40. (Rear face 38 and side are not shown.) The bottom face 31 comprises a flat generally rectangular front portion 32, a flat generally rectangular rear portion 33 in spaced relationship to the forward portion 32 and a curvilinear portion 34, which is one-half of a generally elliptical surface, extending from the rear edge 35 of the forward portion 32 to the forward edge 36 of the rear portion 33. The forward portion 32 of the bottom face 31 is provided with a generally semicircular groove 29 extending from the side 39 to the side 40 and parallel to the face 37. While we have shown the groove 29 as being semi-circular, the groove 29 can be other shapes, for example, rectangular, triangular, or curvilinear and can be placed anywhere between the face 37 and rear edge 35 on the forward portion 32 but it is preferred to make the groove semicircular and to position the groove 29 midway between the face 37 and the rear edge 35 of the forward portion 32. The rear portion 33 of the bottom face 31 is provided with a semi-circular tongue 26 extending from the side 39 to the side 40. The tongue 26 is parallel to the face 38 and the front edge 36 of the rear portion 33. The tongue 26 can also be other shapes, for example, rectangular, triangular, or curvilinear and can be formed anywhere between the forward edge 36 and face 38 on the rear portion 33, but it is preferred to make the tongue semicircular in shape and to place the tongue 26 about midway between the face 38 and the front edge 36 of the rear portion 33.

The lower. part 22 is generally a parallelepiped and has generally rectangular parallel end faces which can be designated as front and rear faces 51 and 51a respectively and generally rectangular parallel side faces 49 and 50 (rear face 51a and side face 50 are not shown), and a flat generally rectangular bottom face 42 parallel to a top face 43. The top face 43 has a flat generally rectangular forward portion 44, a flat generally rectangular rear portion 45 in spaced relationship with the forward portion 44 and a curvilinear portion 46 which is generally elliptical in shape, extending from the rear edge 47 of the forward portion 44 to the forward edge 48 of the rear portion 45. The forward portion 44 of the top face 43 is provided with tongue 27 having the same shape as the groove 29 in the upper part 21 and is positioned on the forward portion 44 so as to mate with the groove 29 on the forward portion 32 of the upper part 21 when the upper part 21 and lower part 22 are fitted together. The rear portion 45 is provided with a groove 28. The groove 28 has the same shape as the tongue 26 and is positioned on the rear portion 45 so that it will mate with the tongue 26 when the upper part 21 and the lower part 22 are joined together as shown. We have shown the groove 29 formed in the forward portion 32 and the tongue 26 formed in the rear portion 33 of the bottom face 31 of the upper part 21 but the groove 29 and the tongue 26 can be interchanged, that is, the groove 29 can be incorporated in the rear portion 33 and the tongue 26 can be incorporated in the forward portion 32. Of course, if the position of the groove 29 and the tongue 26 re reversed as suggested above, then the positions of tongue 27 and groove 28 in the forward portion 44 and rear portion 45 respectively in the top face 43 of the lower part 22 are so reversed so that when the bottom face 31 of the upper part 21 and the top face 43 of the lower part 22 are laid-up contiguously, the groove 29 and the tongue 26 will mate as will the groove 28 and the tongue 27 to thereby interlock the upper part 21 and the lower part 22. Of course, this reversal of groove and tongue can also be applied to the upper part 24 and lower part 25 of the right hand section 23. It can, therefore, be seen that the positions of the tongues and grooves are immaterial so long as they have the same geometric configuration and cooperate to form a tongue and groove interlocking arrangement.

One of the parallel sides 49 is provided with a grooved passage 52 which is shown as generally semicylindrical in shape. The grooved passage 52 extends from the upper part of the curvilinear portion 46 diagonally downwardly to one of the end faces 51 which can be designated as the front face of the lower part 22 and forms a generally semi-elliptical opening a in the front face 51.. When the left hand section and the right hand section 23 are laid-up contiguously or butted together, a generally cylindrical passage 15 is formed by the grooved passage 52 extending from the bustle 13 to the front face 51. The passage 15 is formed so that if either an extension 54a of the axis of the passage 15 or a diagonal line 54 is drawn parallel to the side of passage 15 it will pass through a plane 42a which is an extension of the bottom surface 42 making an angle 4) therewith. The angle (i) should not be more than 89 and not less than 46. It is preferred that the angle 100 be not more than 89 and not less than about 80. The groove 52 can be of any curvilinear surface such as oval, elliptical and-the like or can be square or rectangular and the like. Of course, the port 15a will change in shape consistent with the shape of groove 52.

While the quadripartite bustle and inlet passage refractory assembly has been shown and described, it must be understood that variations of construction can be used, as shown in FIG. 6. Note that in FIG. 6 the inlet passage 15 extends downwardly to the bottom 42 of the side 49. A venturi 53 is shown in the passage 52 to minimize the pressure drop of the hot combustion gases passing through passage 52 into the vertical shaft furnace. The inlet passage 52 can be made without the inclusion of the venturi 53. It does not matter which refractory assembly is used as long as the angle 4) is not more than 89 and not less than 46 and the inlet passage 15 is continuous from the bustle 13 to the front face of the refractory assembly.

While we have shown the integral bustle and inlet passage assembly of the invention as a four piece assembly, it will be understood that the refractory assembly could be made in one piece, two pieces or three pieces; for example, the

top pieces

39 and 24 can be made as one refractory shape, or the bottom pieces 49 and can be made as one piece, thereby resulting in three piece assemblies. If the

top pieces

39 and 24 are made as one refractory shape and the

bottom pieces

49 and 25 are made as one refractory shape, or if the left hand section 20 is made as one refractory shape and the right hand section 23 is made as one refractory shape, then two piece assemblies will result. Of course, the entire assembly could be made in one piece. However, weight, ease of handling in shipping and installation, ease of manufacture, thermal expansion problems and economic considerations will dictate which variations should be used. We prefer either of the quadripartite assemblies shown in FIGS. 3, 4 and 5.

In constructing the upper portion of the refractory lining in the vertical shaft furnace which contains the bustle and inlet passages, it must be recognized that the inlet passages are spaced equidistant apart along the long walls and end walls of the vertical shaft furnace to insure a uniform distribution of hot combustion gases into the pellet bed.

Since the upper left hand section 21 and upper right hand section 24 are identical, the bustle 13 per se can be formed merely by fitting together four parts similar to either part 21 or part 24. Thus, when it is desired to form an assembly 14 without an inlet passage 15, the lower left hand section 22 and lower right hand section 25 are not used. Instead, either

parts

21 or 24 are substituted for the

parts

22 and 25.

As an example of our invention, the hustle and inlet passage refractory assembly as shown in FIG. 5 was installed as part of the refractory lining in the end wall of a vertical shaft furnace. The total aggregate port area, that is, the area through which hot combustion gases are introduced around the vertical shaft furnace, was reduced from 234 square inches-using the prior art method of forming a bustle and inlet passage arrangement in FIG. 1, to l4l square inches using the bustle and inlet passage refractory assembly of the invention as shown in FIG. 5. After a period of five months operation there was no deterioration or movement of the refractory lining surrounding the bustle and inlet passage refractory assembly. Scale build-up on the vertical shaft furnace wall was minimal. Pellet bed temperature was maintained uniform between 2,300 F. and 2,400 F. The pellet quality was as good as, if not better than, pellet quality obtained when using standard bustle and inlet passage construction. Temperature tests wherein nichrome wire test brackets containing a temperature indicator and travelling thermocouples were passed downwardly through the pellet bed showed that no cold spots occurred in the pellet bed and temperature remained constant with a range of about'2,300 F. to 2,400 F.

We claim:

1. A bustle and inlet passage refractory assembly comprising a left hand section and a right hand section, each of said sections being divided into two mating parts, an upper part and a lower part, the upper part of each section having substantially parallel top and bottom faces, parallel front and rear end faces and parallel side faces, the bottom face comprising a forward portion and a rear portion in parallel spaced relationship, said forward portion and said rear portion being joined by a first curvilinear section generally elliptical in shape, said forward portion and rear portion being provided with interlocking and mating means; the lower part of each section having generally parallel top and bottom faces, generally parallel front and rear end faces and parallel side faces, said top face comprising a second forward portion and a second rear portion in parallel spaced relationship, said second forward portion and said second rear portion being joined by a second curvilinear section generally elliptical in. shape, said second forward portion and second rear portion being provided with interlocking and mating means, whereby said top face of said lower part and said bottom face of said upper part are interlocked and mated to form one-half of said refractory assembly, said first curvilinear surface and said second curvilinear surface forming a generally elliptical passage, a grooved passage formed in one of said parallel side faces of said lower part extending substantially diagonally downwardly from the upper part of the second curvilinear section to the front face of the lower part and terminating in an opening in said front face, said opening being in spaced relationship with said bottom face of said lower part, said grooved passage being at an angle of not more than 89 and not less than 46 with said bottom face of said lower part.

2. The bustle and inlet passage refractory assembly of claim 1 wherein the interlocking and mating means comprise a first tongue formed on said forward portion of the upper part extending from one parallel side face to the other parallel side face and being generally parallel to the end faces, a first groove formed on said rear portion of the upper part extending from one parallel side face to the other parallel side face and being generally parallel to the end faces, a second groove formed on said forward portion of the lower part having essentially the same geometric configuration of the tongue formed in the forward portion of the upper part and extending from one parallel side face to the other parallel side face and being generally parallel to the end faces, and a second tongue formed on said rear portion of said lower part having essentially the same geometric configuration of the groove formed in the rear portion of said upper part and extending from one parallel side face to the other parallel side face and being generally parallel to the end faces.

3. The refractory assembly of claim 2 wherein said first and second tongues and said first and second grooves are semi-cylindrical in configuration.

4. The assembly according to claim 1 additionally comprising a constriction in said grooved passage.

5. An improved refractory lining in a vertical shaft furnace having an upper stove and a lower stove, a steel shell and a refractory lining laid-up inside the steel shell and wherein said refractory lining includes a bustle and inlet passage section whereby hot combustion gases are introduced into the interior of the upper stove of the vertical shaft furnace, said bustle and inlet passage section comprising a plurality of quadripartite refractory assemblies comprised of mated contiguous refractory shapes defining between them portions of the bustle and a plurality of inlet passages in the refractory lining.

6. A multipartite refractory assembly for a vertical shaft furnace comprising preformed mating refractory parts which form sections which when laid-up contiguously define a bustle pipe having gas passages extending diagonally downwardly from the bustle pipe to a port in a substantially vertical internal wall of said furnace and intersecting a substantially horizontal plane at an angle of from 46 to 89.

7. The assembly of claim 6 wherein the angle of intersection is from to 89.

8. An improved refractory lining in a vertical shaft pelletizing furnace having an upper stove and a lower stove, a steel shell and a refractory lining laid up inside the steel shell and including a bustle and inlet passage area whereby hot combustion gases are introduced into the interior of the upper stove of the vertical shaft pelletizing furnace comprising:

a. a series of refractory shapes laid-up contiguously one upon another to form a refractory lining having a predetermined thickness and a substantially even cylindrical inside surface in said vertical shaft pelletizing furnace,

b. a multipartite preformed bustle and inlet passage refractory assembly having substantially the same predetermined width as the refractory lining of subparagraph (a) in the refractory lining of said vertical shaft pelletizing furnace and positioned intermediate an upper portion and a lower portion of the refractory lining with the interior face of the said refractory assembly substantially in-line with said upper and lower portions of the refractory lining,

c. said multipartite preformed bustle and inlet passage refractory assembly comprising a series of contiguously laid interengaging substantially L- shaped oppositely disposed refractory shapes defining in the angles of the Us portions of a bustle passage extending around said vertical shaft pelletizing furnace and wherein the bottom and top of the assembly is composed of legs of the oppositely disposed L-shaped refractory shapes, and

d. a downwardly inclined inlet passage passing from the bustle passage to the interior furnace face of said refractory assembly and defined by coacting grooves in side faces of the arms of a plurality of the said L-shaped refractory shapes of said refractory bustle assembly.

9. The improved refractory lining of claim 8 wherein the angle of the downwardly inclined inlet passage intersects a substantially horizontal plane at an angle of from 46 to 89.

10. The improved refractory lining of claim 9 wherein the angle ofintersection is 80 to 89.

Claims

1. A bustle and inlet passage refractory assembly comprising a left hand section and a right hand section, each of said sections being divided into two mating parts, an upper part and a lower part, the upper part of each section having substantially parallel top and bottom faces, parallel front and rear end faces and parallel side faces, the bottom face comprising a forward portion and a rear portion in parallel spaced relationship, said forward portion and said rear portion being joined by a first curvilinear section generally elliptical in shape, said forward portion and rear portion being provided with interlocking and mating means; the lower part of each section having generally parallel top and bottom faces, generally parallel front and rear end faces and parallel side faces, said top face comprising a second forward portion and a second rear portion in parallel spaced relationship, said second forward portion and said second rear portion being joined by a second curvilinear section generally elliptical in shape, said second forward portion and second rear portion being provided with interlocking and mating means, whereby said top face of said lower part and said bottom face of said upper part are interlocked and mated to form onehalf of said refractoRy assembly, said first curvilinear surface and said second curvilinear surface forming a generally elliptical passage, a grooved passage formed in one of said parallel side faces of said lower part extending substantially diagonally downwardly from the upper part of the second curvilinear section to the front face of the lower part and terminating in an opening in said front face, said opening being in spaced relationship with said bottom face of said lower part, said grooved passage being at an angle of not more than 89* and not less than 46* with said bottom face of said lower part.

6. A multipartite refractory assembly for a vertical shaft furnace comprising preformed mating refractory parts which form sections which when laid-up contiguously define a bustle pipe having gas passages extending diagonally downwardly from the bustle pipe to a port in a substantially vertical internal wall of said furnace and intersecting a substantially horizontal plane at an angle of from 46* to 89*.

7. The assembly of claim 6 wherein the angle of intersection is from 80* to 89*.

8. An improved refractory lining in a vertical shaft pelletizing furnace having an upper stove and a lower stove, a steel shell and a refractory lining laid up inside the steel shell and including a bustle and inlet passage area whereby hot combustion gases are introduced into the interior of the upper stove of the vertical shaft pelletizing furnace comprising: a. a series of refractory shapes laid-up contiguously one upon another to form a refractory lining having a predetermined thickness and a substantially even cylindrical inside surface in said vertical shaft pelletizing furnace, b. a multipartite preformed bustle and inlet passage refractory assembly having substantially the same predetermined width as the refractory lining of subparagraph (a) in the refractory lining of said vertical shaft pelletizing furnace and positioned intermediate an upper portion and a lower portion of the refractory lining with the interior face of the said refractory assembly substantially in-line with said upper and lower portions of the refractory lining, c. said multipartite preformed bustle and inlet passage refractory assembly comprising a series of contiguously laid interengaging substantially L-shaped oppositely disposed refractory shapes defining in the angles of the L''s portions of a bustle passage extending around said vertical shaft pelletizing furnace and wherein the bottom and top of the assembly is composed of legs of the oppositely disposed L-shaped refractory shapes, and d. a downwardly inclined inlet passage passing from the bustle passage to the interior furnace face of said refractory assembly and defined by coacting grooves in side faces of the arms of a plurality of the said L-shaped refractory shapes of said refractory bustle assembly.

9. The improved refractory lining of claim 8 wherein the angle of the downwardly inclined inlet passage intersects a substantially horizontal plane at an angle of from 46* to 89*.

10. The improved refractory lining of claim 9 wherein the angle of intersection is 80* to 89*.