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United States Patent m Hyde tni 4,201,543 [45] May 6,1980 [54] HOT BLAST STOVE BREAST WALL [75] Inventor: Jack Hyde, Pittsburgh, Pa. [73] Assignee: Koppers Company,Inc., Pittsburgh, Pa. [21] Appl. No.: 928,244 [22] Filed: Jul. 26, 1978 [51] Int. Cl.*................................................ C21B 9/00 [52] U.S. Q........................................ 432/217; 432/218 [58] Field of Search ............... 432/214, 216, 217, 218 [56] References Cited U.S. PATENT DOCUMENTS 3,488,041 1/1970 Powell et al............................. 432/217 3,806,313 4/1974 Van Laar et al........................ 432/217 Primary Examiner--John J. Camby Attorney, Agent, or Firm--R. Lawrence Sahr [57] ABSTRACT A breast wall construction of a blast furnace hot blast stove includes a free-moving vertical arch composed of reverse wedge interlocking refractory shapes which form a monolithic unit upon differential heat expansion of the breast wall when the blast stove is operating in the on-gas mode. 10 Claims, 5 Drawing Figures 39 15 U.s. Patent May 6, 1980 Sheet 1 of 3 4,201,543 FIG. 1 39 FIG. 2 FIG. 3 U.S. Patent May 6, 1980 Sheet 2 of 3 4,201,543 FIG. 4 57 U.S. Patent May 6, 1980 Sheet 3 of 3 FIG. 5 4,201,543 REFERENCE POINT1800 FROM COMBUSTION CHAMBER MIDPOINT 1 4,201,543 2 higher average temperature, i.e., less of an amount of HOT BLAST STOVE BREAST WALL cold blast being required in the mixture to produce a BACKGROUND OF THE INVENTION uniform temperature, then the more efficient can be the operation of the blast furnace to which the hotter blast 1. Field of the Invention 5 is being fed. The invention is related generally to blast furnace Practically, the increases in surface area within the equipment as utilized in the manufacture of steel and, checker chamber are limited by the requirement that more specifically, to the construction of side-combus the structural integrity of the checker brick must be tion hot blast stoves used to preheat the blast before maintained. It is a well-known axiom that the greater introduction of that blast into a blast furnace. 10 amount of surface area exposed in a checker brick, the 2. Background of the Prior Art thinner the wall sections of the checker must be. But The conventional construction and operation of side- this axiom must be limited in practice by the physical combustion hot blast stoves is aptly set forth in "The limitations applicable to the checkers. Checker brick Making, Shaping and Treating of Steel", 1971 edition, wall or section thickness cannot be reduced below cer published by U.S. Steel Corporation, at pages 439-441. 15 tain limitations because of the lateral crush forces that Included in this treatise are general diagrams of conven are imposed on the checker brick in operation in the tional hot blast stove design and construction. checker chamber. Thus, in known design techniques the The function of the breast wall in a hot blast stove is maximum heat transfer area available within a checker to separate and insulate the side-combustion chamber chamber of a particular size is limited by the lateral from the refractory checker chamber. The breast wall 20 stresses that will be imposed by the differential expan must be structurally sound to support the side-combus sion of the breast wall. tion chamber so as to maintain the refractory checkers Vertical arch forms for hot blast stove breast walls free of lateral stress. In addition, the breast wall is re have long ago been tried as such forms appeared to quired to be gas tight to prevent lateral leakage back provide a rather simplified structure which was rela and forth between the combustion chamber and the 25 tively less costly to construct and maintain as well as checker chamber. providing space economy. However, it was found that Older designs of checkers utilized rather rugged thick the conventional arch pattern, formed with regular sections for the checker cross section. This thick-sec key-shaped refractory brick, increased beyond tolerable tion type of design necessarily reduced the overall area of refractory available in the checker chamber for heat transfer. However, the thick sections were deemed 30 limits the lateral stress imposed onto the checker brick within the checker chamber. Rapid deterioration of the necessary to counteract the lateral forces directed on the checkers from the expansion of the breast wall when checker brick resulted with a commensurate reduction in the ability of the hot blast stove to preheat the blast. the hot blast stove was in the on-gas mode and combus Premature rebuilds of the hot blast stoves were required tion was taking place in the combustion chamber. The 35 which were costly. Thus, the use of breast walls formed combustion produces heat which causes the face of the by a conventional vertical arch was rapidly abandoned breast wall adjacent the combustion chamber to expand in favor of forms including a modified arch similar to at a rate greater than the expansion of the opposite wall those shown in the above reference to "The Making, and the adjoining checker chamber. This expansion Shaping and Treating of Steel". tends to produce a lateral crushing force on the checker 40 The main object of the present invention is to provide brick in the checker chamber. for the simplicity and economy of a vertical arch in hot A further problem caused by the differential expan blast stove breast wall construction, while substantially sion of the breast wall develops from the fact that con eliminating the lateral crush stress on the checker brick ventional breast walls are constructed of individual in the checker chamber, when the hot blast stove is in refractory shapes or brick. When the differential expan 45 the on-gas mode, as caused by the differential expansion sion takes place, the joints between these brick open up of the breast wall. Another object of the invention is to producing passageway through which hot gases can substantially reduce gas passage from the combustion seep, thus derogating from the designed gas passage chamber through the breast wall into the checker cham upwards through the combustion chamber to the dome, ber when the hot blast stove is in the on-gas mode as then downward through the checker chamber. Such 50 well as the elimination of short circuiting of air flowing gas seepage provokes localized hot spots at random from the checker chamber to the combustion chamber points in the checker chamber adjacent the breast wall. during the on-blast mode. These hot spots create rapid deterioration of the checker brick at those points and also tend to produce BRIEF DESCRIPTION OF THE INVENTION uneven heating, thus unbalanced cooling stresses in the 55 In a side-combustion style hot blast stove, as is in checker brick when the hot blast stove is switched to conventional use in conjunction with blast furnace op the on-blast mode and the combustion heat is regener erations, the breast wall, which serves to separate the ated. In addition, highly localized overheating can side combustion chamber from the checker chamber or occur on the metallic support structures related to the regenerator, is constructed in the form of a vertical checker chamber resulting in distortion and/or failure 60 arch, generally equivalent in radius to the radius of the thereof. hot blast stove. The material used in the construction is The design of the checker chamber has progressed, in a refractory, equivalent in characteristics to that con recent years, in the direction of greater efficiency of ventionally utilized in breast wall construction. The heat transfer. Theoretically, it is well known that the vertical arch is composed of refractory shapes designed more surface area available to preheat the cold gas 65 to interlock on all four adjoining sides, preferably along being drawn through those checkers, the higher the the full length of each side, with adjacent similar refrac average heat of the hot blast output from the stove. If tory shapes. Each of the refractory shapes has a charac the hot blast from the stove can be maintained at a teristic reverse key form, that is, it includes tapered 4,201,543 34 vertical sides arranged such that the vertical sides tend refractory section 15b abut the side 25 of the breast wall to converge toward that face of the refractory shape 19 which is formed by the smaller radius of the breast which forms an arc segment of the larger radius arc of wall 19 at each of those ends 21, 23. The steel shell 13, the horizontal arch, and tend to diverge toward that on the other hand, extends past the end faces 27, 29 of face of the refractory shape which forms an arc segment 5 the breast wall 19. of the smaller radius arc of the horizontal arch. The The steel shell 13 is sealably separated from the end refractory shapes are laid up in conventional manner, faces 27, 29 by expansion joints 31, 33 which can be generally with tight mortar joints. Each of the courses formed of any suitable elevated temperature material of refractory shapes is arranged such that the separation which remains flexible, for example, asbestos millboard. between the individual shapes are staggered to be about 10 It will further be noted from referring to FIG. 1 that the midpoint of the refractory shapes of the adjacent the shell wall 15 extends from both ends 21, 23 of the courses below and above, respectively, as is common breast wall 19 and abuts the breast wall 19 on the side 35 practice in masonry construction. which is formed by the larger radius of the breast wall The breast wall adjoins the shell wall of the hot blast 19 adjacent the checker chamber, generally designated stove at the points of the intersections of the regular 15 by the numeral 37, a portion of which is illustrated in arcs of both the breast wall and the shell wall. There FIG. 1. may be an expansion joint interposed at both of the The checker chamber 37 is composed of checker points at which the breast wall intersects the arc of the brick 39, preferably of the type disclosed in U.S. Pat. shell such that the arc length of the breast wall can No. 3,488,041. Other types of checker brick may be increase and decrease without distorting the shell. The 20 used, the major criterion in selection being a maxim- adjunctures of the breast wall with the shell wall may be mumization of the surface area available for heat trans arranged such that the breast wall is prevented from fer. moving laterally, in a horizontal direction, in relation to The breast wall 19 is composed of refractory shapes, said shell wall. generally designated by the numeral 41. The refractory For a further understanding of the invention and 25 shapes 41 are laid up in a conventional manner, alternat features thereof, reference may be made to the follow ing the separations, or joints, of each course to fall about ing detailed description of the preferred embodiment of midpoint of the joints separating the refractory shape 41 that invention and the drawing figures which illustrate of the vertically next adjacent courses. Referring to that preferred embodiment, as well as the appended FIG. 1, the joints 43, shown in phantom outline, depict claims. 30 the arrangement of the refractory shapes 41 in the BRIEF DESCRIPTION OF THE DRAWINGS course immediately beneath the course shown in solid lines. Thejoints 45 of the course of refractory shapes 41, FIG. 1 is a schematic plan view of a section of a hot as shown by solid lines in FIG. 1, fall about midpoint blast stove illustrating a side combustion chamber, a between the joints 43. The refractory shapes 41 are laid breast wall and a portion of the shell wall intersecting 35 up using conventional tight mortar joints to separate the breast wall at two points, all in accordance with the each refractory shape 41 from the next horizontally present invention. adjacent refractory shape 41, as well as to separate each FIG. 2 is a plan view of a typical refractory shape in course of refractory shapes 41 from the next vertically accordance with the invention. adjacent course of refractory shapes 41. FIG. 3 is a side view of the refractory shape of FIG. 40 In the breast wall 19 a typical refractory shape is 2 as viewed from III--III. designated by the numeral 41a and is shown enlarged in FIG. 4 is an orthographic projection of the refractory FIGS. 2, 3 and 4. The general design of all the refrac shape of FIG. 2, enlarged in proportion thereto. tory shapes 41 follows the pattern of shape 41a and is FIG. 5 is a schematic plan view of a hot blast stove complementary thereto- in a manner which will be illustrating the design of the refractory shapes of the 45 readily comprehended by one skilled in the art. breast wall in accordance with the present invention. As is suggested in FIG. 1, the steel shell 13 is continu DETAILED DESCRIPTION ous, surrounding the hot blast- stove in the form of a vertical cylinder. The shell wall 15 extending from the Referring to FIG. 1, there is illustrated a section of a side 35 of the breast wall 19, from end 21 to end 23 of hot blast stove, generally designated by the numeral 11. 50 the breast wall 19, is also continuous and forms the The hot blast stove section 11 includes a portion of the checker chamber 37. steel shell 13, which surrounds the hot blast stove, and In designing the refractory shapes 41 for the first a shell wall consisting of a refractory section 156 and an course, and each alternate course therefrom, for the insulation section 15a. breast wall 19, a reference point is first located on the Also included in the hot blast stove section 11 are a 55 steel shell 13. Referring to FIG. 5, the reference point is side combustion chamber 17 and a breast wall, generally 180, or one half of the circumference of the steel shell designated by the numeral 19. The combustion chamber 13, away from a point on the steel shell 13 adjacent to 17 is constructed of a refractory material of sufficient the midpoint of the combustion chamber 17. From that character to withstand the elevated temperatures of reference point, a first joint line is located which falls on combustion developed in the operation thereof in the 60 a reference line which may be drawn from the reference on-gas mode. point to the point on the steel shell 13 adjacent to the As shown in FIG. 1, the breast wall 19 forms a verti midpoint of the combustion chamber 17, through the cal arch, that is, the projection of the arc of the arch center of the hot blast stove. In FIG. 1 that first joint extends vertically. It will be noted from referring to line is equivalent to the joint 45 which forms the right FIG. 1 that the portion of the shell wall 15 that is adja 65 edge of refractory shape 41a. From the reference line, cent to the combustion chamber 17 extends to intersect upon which falls the first joint line, additional joint lines the arc of the breast wall 19 at ends 21, 23 of the breast are established, the extension of each passing through wall 19 such that both the insulation section 15a and the the reference point and each having an angle separating 64,201,543 5 it from the next adjacent joint line, or lines, which are a fillet, tapering adjacent adjoining surfaces to abut. The generally equal to the angle separating each of the other face surfaces of the midportion 53 are parallel to the joint lines for the next adjacent joint line or lines. Each corresponding side surfaces of the combustion portion of the thus established joint lines is extended to pass 51 and checker portion 55. through the breast wall 19. Each of the joints 45 falls on 5 The offset to the left of the midportion 51 results in a a joint line. The angle which separates succeeding joint left side projection 61 and a right side recess 63 of the lines is set to conform to convenient sizes for manufac typical refractory shape 41a, as illustrated in FIG. 2. As turing the refractory shapes 41, such sizes which are. illustrated in FIG. 3, the midportion 53 is also offset well known to those skilled in the art. Because all of the downward, or to the right, in that side or elevation view joint lines converge and pass through a single point, the 10 of the typical refractory shape 41a. This downward reference point, and all of the joints 45 between the offset results in a bottom side projection 65 and a top refractory shapes 41 fall on the joint lines, the side edges side recess 67. of each refractory shape 41 are tapered, tending to As shown in FIGS. 2 and 4, face 49 has a concave converge toward the checker chamber and beyond it to curve which corresponds in arc characteristics to the intersect the reference point on the steel shell 13 oppo 15 side 25 of the breast wall 19. Similarly, face 47 has a site the breast; wall 19, developing the characteristic convex curve which corresponds in arc characteristics reverse key form. Thus, the face 47 which forms part of to the side 35 of the breast wall 19. Both faces 47 and 49 side 35 of the breast wall 19 spans a shorter distance, form a section of walls 35 and 25, respectively, when from edge to edge of a refractory shape 41, than does the typical refractory shape 41a is positioned in place in the face 49 which forms part of side 25 of the breast wall 20 the breast wall 19, as shown in FIG. 1. Alternately, the 19 as measured on lines approaching the perpendicular faces 47 and 49 could be straight, forming straight sur from edge to edge (these lines can never be perpendicu face segments which, taken together, form an arc. lar to both edges, as those edges are not parallel). For The peripheral left side projection 61, bottom side the course of refractory shapes 41 vertically next adja projection 65, right side recess 63 and top side recess 67, cent to the first course, and for each alternate course of 25 tracing the side periphery of the typical refractory refractory shapes therefrom, instead of the first joint shape 41a, as viewed in FIG. 4, form a tongue-and- line falling on the reference line, two first joint lines are groove type interlock means operable with the next established, utilizing the same angle that is used to sepa adjacent refractory shapes 41, both horizontally and rate joint lines in the first course of refractory shapes 41. vertically. Horizontally, in any given course of refrac These two first joint lines are positioned so that the 30 tory shapes 41, the left side projection 61 of a typical reference line bisects the angle therebetween. From refractory shape 41a fits into the right side recess 63 of these first two joint lines, the other joint lines are estab the next adjacent refractory shape 41 to the left; like lished in the. same manner as described for the first wise, the right side recess 63 of that typical refractory course of refractory shapes 41. Likewise, the same com shape 41a receives the left side projection 61 of the next mentary concerning the taper of the refractory shapes 35 adjacent refractory shape 41 to the right. The projec 41 applies equally to all courses of refractory shapes 41. tions and recesses are complementary; however, as The next step in designing the refractory shapes 41 of mentioned before, a tight mortar joint is used therebe the breast wall 19 is to establish a first and second arc tween such that the projections and recesses do not line, tracking the arc of the breast wall 19 and dividing actually touch each other. This tight mortar joint en the thickness of the breast wall 19 into three parts of 40 sures that the breast wall 19 will be gas-tight in opera approximately equal thickness. The first part, adjacent tion. to the combustion chamber, will be referred to as the Vertically, between courses of refractory shapes 41, combustion portion 51. The second part, adjacent to the the bottom side projection 65 of a typical refractory combustion portion 51, will be referred to as the mid shape 41a fits into the top side recesses 67 of the next portion 53. The third part, adjacent to the checker 45 adjacent refractory shapes 41 below; likewise, the top chamber and the midportion 53, will be referred to as side recess 63 of that typical refractory shape 41a re the checker portion 55. Those sections of the first and ceives the bottom side projections 65 of the next adja second arc lines which are applicable to typical refrac cent refractory shapes 41 above. Here, again, the actual tory shape 41a are approximated in FIGS. 2, 3 and 4 as joints are tight mortar joints to prevent gas leakage. the dividing lines between the combustion portion 51, 50 Referring to FIG. 1, it will be noted that the ends 21, the midportion 53, and the checker portion 55. The 23 of the breast wall 19 are composed of end refractory extension of those first and second arc line sections are shapes 69, 71. These end refractory shapes 69, 71 differ readily visualized on FIG. 1 by visually following the from the refractory shapes 41 that are used to compose arrangement of alternating joints 45, 53 from end 21 to the breast wall 19 in only one significant way, that is, in end 23 of the breast wall 19. 55 that the end refractory shapes 69, 71 have cropped ends The typical refractory shape 41a, illustrated in FIGS. which are squared off to meet the expansion joints 31, 2, 3 and 4, is susceptible to the approximate general 33, forming the end faces 27, 29 of the breast wall 19. description of a rectangular box with an offset center In operation in the hot blast stove on-combustion section, tapered sides and curved ends. FIG. 2 is a plan mode, combustion occurs vertically up through the view, or a view from directly above, looking down 60 combustion chamber 17, concentrating heat on that thereon, of the typical refractory shape 41a. As seen in portion of the side 25 of the breast wall 19 which is FIG. 2, the midportion 53 is offset to the left from the adjacent to the combustion chamber 17. The side 25, combustion 51 and the checker portion 55. The midpor being differentially hotter in this location than the bal tion 53 is also depressed below the top surface plane 57 ance of the breast wall, tends to expand the refractory of the combustion portion 51 and the checker portion 65 shapes, both in a direction along the arc of the breast 55. The midportion 53 is surface connected to the com wall 19 as well as toward the checker chamber 37. This bustion portion 51 and the checker portion on all side expansion tends to force the whole breast wall 19 to surfaces by a draft transition 59 which is in the form of bulge toward the checker chamber 37. However, the 4,201,543 87 interlock means, as previously described, prevents any a characteristic reverse key form, said refractory shapes single refractory shape 41 from moving out of position being arranged in said breast wall, said reverse key form in respect to all adjacent refractory shapes 41, both tending to converge toward that side of the said breast horizontal and vertical. Therefore, all of the refractory wall which forms the larger arc radius of said horizontal shapes 41 of the breast wall 19 must move with each 5 arch, said breast wall adjoining the shell wall of said hot other. The bulge effect on the breast wall 19 is such that blast stove at the points of intersection of the arc of said it tends to increase the radius of the arc of the breast shell wall with the arc of said vertical arch. wall 19. This tendency to increase radius produces pres 2. The invention described in claim 1 wherein said sure on the joints 43, 45 due to their tapered design, points of intersection of the said arc of said shell wall forcing the refractory shapes 41 to take on monolithic 10 with the said arc of said vertical arch are formed of structure characteristics such that the breast wall 19 can elevated temperature service expansion joints, the arc only move as a single unit. Since the breast wall 19 is length of said arc of said horizontal arch tending to wedged between the sections 15a and 15b of the shell increase and decrease with temperature changes with wall 15, about the ends 21, 23 of the breast wall 19, the out distorting said shell wall. breast wall 19 is prevented from moving as a unit. In 15 3. The invention described in claim 1 wherein said creased combustion heat, producing increased differen adjunctures of said breast wall with said shell wall are tial temperatures and increased expansion of side 25, arranged to prevent said breast wall from moving later merely serves to increase the compressive force on ally, in a horizontal direction, in relation to said shell joints 43, 45. wall. The end result of the present invention is to produce 20 4. The invention described in claim 1 wherein said a checker chamber 37 substantially free of lateral crush masonry refractory construction includes tight mortar ing forces, thus allowing the design of checker brick 39 joints between each of said refractory shapes. with significantly greater area for heat transfer and 5. The invention described in claim 1 wherein said thinner refractory cross sections. means for interlocking is located along the full length of According to the provisions of the patent statutes, the 25 each adjoining side of said refractory shapes. principle of the present invention has been explained 6. The invention described in claim 1 wherein said and the preferred construction and mode of operation interlock means is of the tongue-and-groove type. have been illustrated and described in what is now con 7. The invention described in claim 6 wherein said sidered to represent its best embodiment. However, it is interlock means is of the tongue-and-groove type. to be understood that, within the scope of the appended 30 8. The invention described in claim 6 wherein said claims, the invention may be practiced otherwise than is tongue-and-groove type interlock means includes draft specifically illustrated and described. transitions in all adjoining side surfaces of said interlock What is claimed is: means which abut between said refractory shapes. 1. In a side combustion chamber hot blast stove, used 9. The invention described in claim 1 wherein said in conjunction with a blast furnace in steel manufactur 35 reverse key shape forms as arranged in said breast wall ing operation, a breast wall comprising a masonary all tend to converge on a single point, located adjacent refractory construction of multiple vertical courses of said skin wall, at the opposite side of said hot blast stove refractory shapes arranged in a vertical arch, said re from the location of said side combustion chamber. fractory shapes having means for interlocking and being 10. The invention described in claim 1 wherein said interlocked, along adjoining sides, in a complementary 40 arc of said horizontal arch is about equal in radius to the manner such as to prevent individual movement in rela tion to each other, each of said refractory shapes having radius of said arc of*sai*d s*he*ll w*all. 45 50 55 60 65