US3212478A - Brick-lined, water-cooled industrial furnace door - Google Patents

Description

BRICK-LINED, WATER-COOLED INDUSTRIAL FURNACE DOOR Filed April 9, 1962 2 Sheets-Sheet 2 0/71 l5 Q 57 542 I3 "ff" 1! 3% l5 21 I 5 14 I I g- '9 31+ 58 27 :2 INVENTOR.

OTTWIN LBRAUN. 25

ATTORNEYS.

United States Patent 3,212,478 BRICK-LINED, WATER-COOLED INDUSTRIAL FURNACE DOOR Ottwin L. Braun, Pittsburgh, Pa., assignor to Reliance Steel Products Company, McKeesport, Pa., a corporation of Pennsylvania Filed Apr. 9, 1962, Ser. No. 186,265 7 Claims. (Cl. 122-498) This invention relates to a brick-lined, water-cooled, industrial furnace door, and more particularly to a watercooled door having a refractory brick lining supported on the door by shelves secured to the door.

It is customary practice to utilize refractory-lined doors for open-hearth furnaces to prevent failure due to the intense heat to which such doors are exposed. In the past the doors of this type have either been lined with refractory brick, or with a refractory compound or ram. ming material bonded to the door by means of tie elements which are firmly connected to the door but which are embedded for the most part within the composition. Such doors are often water-cooled by forming the door with hollow sections adjacent the lining for transfer of the heat encountered by the lining to a liquid within the hollow door sections. An example of one such door is that disclosed in my copending application Serial No. 142,371, now Patent No. 3,156,218, filed October 2, 1961, and entitled Forced Circulation Water-Cooled Furnace Door.

A refractory door lining in general use in open-hearth furnace doors is composed of a ramming material with a chromite base having a melting point of about 3720 F. A door lining with a higher melting point is necessary, however, for doors on open-hearth furnaces which employ oxygen to augment the regular furnace fuel. A ramming material having a melting point in the order of 4950 F. would be desirable, but characteristics of such materials render them unsuitable for use under conditions experienced by doors of open-hearth furnaces wherein radical temperature changes and sustained high temperatures are encountered. Thus, one of the major problems encountered by those skilled in the art of furnace doors is that of providing door structures having linings which will resist flaking or disintegration due to the high temper-ature environment wherein these doors are employed, for if the lining is destroyed the metal of the door is exposed directly to the heat of the furnace and is also destroyed. Consequently, a door which can withstand high temperatures over a long period of time, that is, for repetitive furnace heats, is highly desirable; otherwise, thedoor must be removed frequently from the furnace for relining, an operation which normally requires a costly investment of time, material and labor.

The present invention provides a panel door for openhearth furnaces which has a lining of bricks of magnesite which are supported on a hollow section of the door by means of shelves. Upon exposure to elevated temperatures the shelf material and the magnesite brick, which are metal clad, fuse together at their heat-exposed surfaces and form a thin molten metallic surface. The magnesium core of the brick begins to flux under the intense heat and will bond to the molten metal. The fusion of the brick material to the metal retards further melting or distintegration of the lining the rate of transfer of heat from the door lining to the coolant circulated in the hollow panel of the door balances the rate of melting of the door lining material.

It is an object of the present invention to provide a new and improved water-cooled furnace panel door having a brick lining.

Another object is the provision of a water-cooled 3,212,478 Patented Oct. 19, 1965 ice furnace door with a lining constructed of brick courses which are layered on shelves removably positioned on the door such that lining changes can be made by simply removing the shelves from their assembly position on the door.

A further object is to provide a water-cooled furnace door having a lining of elements which fuse together under heat of a furnace to form a surface layer adjacent the combustion zone of the furnace which retards the thermal destruction of the refractory material of the mug;

One modification of the instant invention may include a door having brackets fastened to one door face, shelves with depending tabs fastened removably to the brackets, and brick layered in courses supportingly separated by the shelves, the brick and shelves being fused by the heat of the furnace to form a lining with a surface which retards thermal destruction of the lining refractory.

A complete understanding of the invention may be had from the following detailed description of a specific embodiment thereof when read in conjunction with the appended drawings, wherein:

FIG. 1 is a front elevational view of the door;

FIG. 2 is a sectional plan view taken along the line HII of FIG. 1;

FIG. 3 is a vertical sectional view taken along the line III-11l of FIG. 1, which is the axis of symmetry of the door;

FIG. 4 is a rear view of the door;

FIG. 5 is a fragmentary enlarged view of the attachment between the door shelves and the door back plate; and

FIG. 6 is an isometric view of a brick for use in making the door.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1, which illustrates a preferred embodiment, a furnace door 11 generally rectangular in shape with a planar front plate 12 which, when the door is installed on a furnace, lies opposite the side of the door exposed directly to the furnace heat.

As customary in the art of open-hearth furnace doors, door lining inspection openings 13 and a furnace inspection port 14 are provided through the front plate 12 of the door 11, and, as best illustrated in FIG. 3, sealed to the lining inspection openings 14 are open-ended sleeves 15 which extend thnough aligned similar openings 16 in a planar back plate 17 spaced laterally from the front plate 12 so as to provide an interstice or hollow portion 18 between the plates. The open-ended sleeves 15 terminate at the rear surface of the back plate 17. On the other hand, the furnace inspection port 14 is lined with a pipe 19 which extends across the interstice 18 and through an aperture 21 in the back plate 17 which is coaxial with the port 14 through the front plate 12. As best shown in FIG. 3, the pipe 19 terminates at the rear surface of the back plate 17.

A flange 22 of U-shaped cross-section, FIG. 3, extends across the door bottom and is of a heavier gauge steel than the steel of the remaining door structure to better withstand wear as the door bottom is repeatedly lowered in forceful contact with a door threshold of the furnace, not shown. The door back plate 17 has its periphery 23 turned toward the rear and is inclined toward the door center. Across the door bottom the flange 22 is fixedly sealed, as by welding, to the terminal portion 24 of the back plate periphery 23 in a manner such that the hollow portion 18 between the door plates 12 and 17 is contiguous with a hollow section 25 existing between the flange 22 and the periphery 23 of the back plate 17. The side marginal portions 26 and the top marginal portion 27 of the door 11 are designed with a continuous channel 28 formed by turning of the side and top edge portions 29 of the back plate 17 outwardly from the door center. The front plate 12 has a r'earwardly directed flange 31 which is suitably sealed to the outwardly turned side and top edge portions 29 to complete the design of the channel 28. The channel 28 is in open communication with the hollow section 25 across the door bottom and with the hollow portion 18 between the spaced planar plates 12 and 17.

By fashioning the door structure in the manner described, the door is properly constructed as a hollow panel door. Within the hollow portion thereof a coolant, such as water, may be circulated to transfer heat from the door to avoid its mechanical and chemical destruction by intense heat. For this purpose a liquid for circulation may be force-fed through an inlet pipe 32 which passes through the top marginal portion 27 of the door through top edge portion 31 of the front plate 12 and depends in the channel 28 of the side marginal portion 26 to a point above the bottom hollow section 25. On the opposite side marginal portion 26 from the inlet pipe 32 is an outlet fitting 33 which extends only through the top edge portion 29 into communication with the hollow channel 28 as depicted in FIG. 2. Plugged washout openings 34 are provided through the side portions 26 of the door 12 and open into the bottom hollow section 25. By connecting a supply of water or other coolant liquid under pressure to the inlet pipe 32, the hollow portion 18, bottom hollow section 25, and top and side continuous channel 28 are flooded, and the fluid is circulated to the outlet fitting 33 under pressure of the force-fed coolant. Accordingly, the back plate 17, which is adjacent the heat of the furnace when the door is in use, transfers heat from a lining tothe coolant for removal through the outlet fitting 33, and the door lining is consequently cooled. The door is lowered and raised into position over the charge opening of the open-hearth furnace, for example, by suitable linkage means or cables connected to upstanding apertured lugs 35 and by a handle or eye member 36 fastener to the top of the door 12.

With the rigid frame of the structural panel door design having been treated, the lining 37 of the door will now be explained with attention directed particularly to FIGS. 3, 4 and 5. As shown best in FIG. 3, a recess 38 is formed which is bounded by the re-entrant and rearwardly directed periphery 23 of the back plate 17. Into this recess courses of brick 39 are placed to compose the lining 37. The brick 39 preferably are the so-called metalcase type, that is, the brick 39 are wrapped by a band of steel about the flat surfaces of the brick exclusive of the brick ends. The bricks are composed of the mineral magnesite, which is magnesium carbonate, MgCO as found in nature. Such a brick is shown in FIG. 6 wherein the brick 39 has a metal wrapping 3911 about the long faces. of the refractory body 3%, the ends being uncovered. The particular brick here shown is notched at 39a to clear a shelf bracket as hereinafter described, but this notch is required only in some of the bricks.

superposed on each single course of the magnesite brick 39 is a shelf 41 which is either tack welded to the back plate 17, or fastened removably to the back plate by spaced brackets 42 which are fixed to the back plate, FIG. 5. The brackets have a downwardly tapered opening 43 into which correspondingly tapered tabs 44 fit frictionally. The tabs 44 are in turn fixed, as by welding, to the lower surface of the shelf 41 at spaced intervals matching the spacing between brackets 42 fixed in-line to the plate 17. The inner edge of each shelf snugly contacts the planar surface of the back plate 17 to which they are fastened by either of the two mentioned techniques. The width of each shelf 41 is the same as the width of the metal-clad brick 39 such that the rear face of the lining, which is that surface to be directly exposed to the furnace heat, is substantially uniform. The rear plate periphery 23 ex tends slightly beyond the exposed surface of the lining to better key the assembled lining in position on the door. The bricks 39 are suitably notched to clear the brackets, bringing the face of each brick in contact with the surface of the back plate 17 of the door.

In the assembly of the lining 37 within the recess 38 the first course of metal-clad brick is laid adjacent the bottom of the recess, and a shelf may be tack welded to the plate 17 above the first course. Prefenably, however, the shelves are fastened to the back plate 17 into place above the first course by means of the tabs and brackets as above described. The courses of bricks and shelves are alternated until the laying of the brick courses is completed to consume the volume of the recess. Next, the exposed rear surfaces of the metal casing of the brick are tack welded to the steel plate shelves 41, fixing the lining 37 as a Whole into position in the recess 38 for handling of the door prior to and during installation of the furnace.

When the assembled door with lining 37 is aligned on the furnace, the intense heat of the furnace radiating on the rear face of the lining 37 melts the exposed shelf edges and the exposed metal casing surface of the brick, giving rise to a thin molten mass of the merged metals. The high temperature begins to cause the magnesium of the magnesite brick to fuse and to merge with the molten metals. The cooling of the lining prevents further melting of the lining materials by the forced circulation system provided in the panel of the door; however, an equilibrium is established between the rate of melting of the lining material and the rate of cooling of the lining. Thus, by the incorporation of the magnesite brick which has a high melting point in a furnace door lining the useful life of the door is prolonged over that of the conventional bricklined furnace doors.

It is manifest that the above-described embodiment of the invention is merely illustrative, and that numerous modifications may be made within the spirit and scope of the invention.

I claim:

1. A furnace door comprising a rigid hollow frame with a planar rear surface having a recess, the frame being of a size and configuration to span an access opening of a furnace in communication with the heating zone of the furnace, the recess being of a depth equal to a dimension of a clad refractory brick, metal shelves attached to the rear surface of the frame and within the recess at vertically-spaced intervals with the shelf outer edges being in a common plane which includes one wall of a brick placed thereon, the shelves being of lengths to span the recess and of widths substantially equal to the depth of the recess, and refractory magnesite bricks with metal casings positioned in courses on the vertically-spaced shelves, the magnesium of the magnesite brick, the metal of the exposed walls of the brick casings, and the shelf edges being fused by direct exposure to the furnace heat to form a thin molten surface layer across the recess whereby stability of the magnesite brick is maintained and the brick is preserved against heat destruction.

2. A furnace door as in claim 1 wherein the shelves are attached removably to the rear surface of the frame by tabs depending at intervals along the shelf inner edges and received within spaced brackets fixed to the rear surface of the frame within the recess, and the bricks are notched to fit snugly against the surface with the brackets within the notches.

3. A furnace door as in claim 1 wherein the shelves are fixed by Welding to the rear surface of the frame.

4. A furnace door comprising a hollow frame with a central recess, shelves attached to the door within the recess and having outer edges in a common plane, and metal clad magnesite brick fastened to the shelves Within the recess and terminating in the common plane forming a lining of molten metals of the shelf edges, the metal of the metal clad brick which is exposed, and the magnesium of the brick across the heat exposed surface of the door.

5. A furnace door comprising a hollow panel, means for circulating a coolant through the panel, a lining of metal-clad magnesite brick layed in courses across the face of the panel for exposure to furnace heat, and shelves positioned between the brick courses and fastened to the metal of the metal-clad brick and to the face of the panel fastening the lining in place on the door panel, the shelf edges and the metal clad brick sides directly exposed to heat of the furnace being in a common plane and fused together with magnesium of the brick to form a lining surfaoe of molten metals.

6. A furnace door comprising a hollow vertical panel with a continuous rearwardly-directed hollow marginal portion opening into the hollow vertical panel, the door having a re-entrant portion bounded by the continuous rearWardly-directed hollow marginal portion and the rear face of the panel, an inlet pipe fixed to the door hollow marginal portion and extending from without the door into the hollow portion and terminating above the bottom of the door, an outlet conduit opening into the hollow marginal portion opposite the inlet pipe, refractory magnesite brick layed in courses within the re-entrant portion, and metal shelves fastened to the rear face of the panel and positioned between courses of the brick and fixed to the brick by fusion of the magnesium of the brick to the shelves at their outer edges, the shelf outer edges lying in a plane which includes the exposed sides of the brick and fused therewith to form a molten lining surface with melted magnesium of the brick.

7. A furnace door comprising a front plate, a rear plate spaced from the front plate, the marginal portions of the plates being rearwardly turned and joined to form a hollow peripheral door portion opening into the space between the front and rear plates, an inlet pipe connected to the door and extending Within the peripheral door portion, an outlet conduit connected to the door in communication with the hollow peripheral door portion, the rear plate and its marginal portion forming a re-entrant portion in the rear face of the door, refractory metal-clad magnesite brick layed in courses within the re-entrant portion nesite brick layed in courses within the rte-entrant portion, metal shelves fastened to the rear face of the door within the recess and positioned between the layers of brick and extending to a plane including the exposed face of the metal of the clad brick, the magne-site of the brick, the exposed metal of the metal of the brick, and the exposed edges of the shelves being melted to form a surface layer across the recess with the rate of melting of the materials being regulated by the amount of cooling effected by passing a coolant through the inlet pipe and hollow portion to the outlet pipe.

References Cited by the Examiner UNITED STATES PATENTS 2,325,945 8/43 Fuchs 122-498 2,426,568 8/47 Sontz 1l0l73 2,475,102 7/49 Longacre ll0-173 2,512,439 6/50 Richards -180 2,673,534 3/54 Robinson 110173 2,764,887 10/56 DAmbly 1101 2,781,006 2/57 Heller 1l0-1 FREDERICK L. MATTESON, JR., Primary Examiner.

PERCY L. PATRICK, ROBERT A. OLEARY,

Examiners.

Claims (1)

1. A FURNACE DOOR COMPRISING A RIGID HOLLOW FRAME WITH A PLANAR REAR SURFACE HAVING A RECESS, THE FRAME BEING OF A SIZE AND CONFIGURATION TO SPAN AN ACCESS OPENING JOF A FURNACE IN COMMUNICATION WITH THE HEATING ZONE OF THE FURNACE, THE RECESS BEING OF A DEPTH EQUAL TO A DIMENSION OF A CLAD REFRACTORY BRICK, METAL SHELVES ATTACHED TO THE REAR SURFACE OF THE FRAME AND WITHIN THE RECESS AT VERTICALLY-SPACED INTERVALS WITH THE SHELF OUTER EDGES BEING IN A COMMON PLANE WHICH INCLUDES ONE WALL OF A BRICK PLACED THEREON, THE SHELVES BEING OF LENGTHS TO SPAN THE RECESS AND OF WIDTHS SUBSTANTIALLY EQUAL TO THE DEPTH OF

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