US3440978A

US3440978A - Corrugated furnace seal

Info

Publication number: US3440978A
Application number: US634265A
Authority: US
Inventors: Byram Jamshed Magol
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1967-04-27
Filing date: 1967-04-27
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29

Description

April 29, 1969 B. J. MAGOL I 3,

CORRUGATED FURNACE SEAL Filed April 27. 1967 INVENTOR, BYRAM J. MAGOL Anon-mgr United States Patent US. Cl. 110-165 2 Claims ABSTRACT OF THE DISCLOSURE A sealing means for use in the opening between a furnace bottom and an ash hopper disposed beneath the furnace. The sealing means comprise explosively formed corrugated plates which are mounted on the furnace bottom and extend around the periphery of the ash hopper.

CROSS-REFERENCE TO RELATED APPLICATION The present application is a continuation in part of applicants copending application Ser. No. 447,709, filed on Apr. 13, 1965, for Corrugation Forming by Explosives, now US. Patent No. 3,372,565, which was granted on Mar. 12, 1968.

BACKGROUND OF THE INVENTION In large vapor generators it is necessary to provide a separate ash hopper which is located beneath the furnace bottom. The space between the furnace bottom and the ash hopper is generally sealed by means of substantially fiat plates which are mounted on the furnace bottom and extend around the periphery of the ash hopper. A water trough which usually extends around the ash hopper is provided for cooling and sealing purposes.

The use of conventional sealing plates in the space between the furnace and ash hopper has presented a problem in that extreme temperature changes occur over a relatively short period of time, resulting in damage to the sealing plates. A variety of reinforcement structures have been used with the sealing plates to prevent deterioration. These have proven to generally be inifective and difficult to fabricate. In accordance with the present invention, sealing means have been provided which comprise baflle plates integrally formed with a plurality of elongated grooves. In the past it has been difficult to manufacture baffle plates integrally formed with elongated grooves by means of conventional die methods of fabrication. The corrugated panels of the instant application can be fabricated in accordance with the method disclosed in applicants corresponding copending application referred to above, wherein shaped charges are supported against or closely adjacent to a panel which is to be formed. The major portions of the explosives are located along the lines of the contours which are to be produced, with the shape and size of the charges being dictated by the preselected shape of the contours. The charges are simultaneously detonated in a suitable medium to develop localized shock waves which are transmitted to adjacent areas on the panel. The latter is supported at points remote from the contour forming explosives such that the shock waves produce a rapid and localized substantially free-forming expansion of the panel in the adjacent area, thereby developing high strength corrugations. By virtue of the localization of the expansion, the overall dimensions of the panel are not changed. Thus, by employing this method of explosive formation, various shaped contoured panels with high strength corrugations can be conveniently and eco- 3,440,978 Patented Apr. 29, 1969 nomically manufactured for use as the sealing means between the furnace bottom and ash hopper.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a seal for use between a vertically disposed furnace bottom and ash hopper having a top opening which is spaced apart from the furnace bottom. Mounted on the furnace bottom are bafile plates which form a closure between the furnace bottom and the ash hopper. The baffie plates are integrally formed with a plurality of elongated corrugations which are substantially parallel to each other and the longitudinal axis of the furnace bottom, such that thermal expansion is absorbed by the corrugations.

BRIEF DESCRIPTION OF THE DRAWINGS The above brief description as well as further objects, features, and advantages of the present invention will be more fully appreciated by referring to the following detailed description of a presently preferred but none theless illustrative embodiment in accordance with the present invention, when taken in connection with the accompanying drawings wherein:

FIG. 1 is a diagramamtic sectional view of a furnace bottom and ash hopper between which the corrugated sealing means of the instant invention are employed;

FIG. 2 is a transverse sectional view of the sealing means taken along the lines 22 of FIG. 1 and looking in the direction of the arrows; and

FIG. 3 is an enlarged elevational view of a corrugated panel, shown removed from the furnace bottom.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, in accordance with the present invention there is provided corrugated bafile plates 10 shown supported on a furnace bottom 12. Directly beneath the furnace bottom 12 there is located an ash hopper 14. It should be understood that the furnace bottom 12 is part of a relatively large vapor generator which is not shown in the drawings for the sake of clarity. The furnace bottom 12 includes water filled tubes 16 which are fin welded together to form the furnace walls that define a combustion chamber 18. The lower portion of combustion chamber 18 is provided with a throat opening 20 for communicating with ash hopper 14.

The ash hopper 14 is formed with a relatively heavy concrete bottom wall 22, four upstanding side walls 24 and a top opening 26, which define a receptacle chamber 28 having a rectangular cross section. The ash hopper 14 is supported at ground level denoted by the letter G by means of four upright stanchions 30 mounted on the corners of bottom wall 22. A refractory material is generally sprayed on the exposed surfaces of receptacle chamber 28, and the side walls 24 are reinforced by means of outer plates 32, fabricated from steel sheets.

Included in ash hopper 14 is a trough 34 which extends around the periphery thereof. The trough 34 is formed with a bottom wall 36 and side wall 38 that define a continuous liquid circuit 40 along the upper portion of outer plates 32. The trough 34 is formed by joining together four bottom walls 36 and four side walls 38, and a continuous butt weld 42 is fabricated at the junction between bottom walls 36 and outer plates 32. The liquid circuit 40 is preferably supplied with water by means of a supply line 44, having a regulating valve 46, which is mounted in side wall 38 in flow communication between circuit 40 and a source of water not shown in the drawings. An overflow conduit 48 is formed in one of the side walls 24 and an overlying outer plate 32 for conveying overflowing water to receptacle chamber 28. Accordingly, water is continuously circulated through trough 34 for cooling baffle plates and forming a gas tight closure.

As best shown in FIG. 1, the battle plates 10 are generally configured in accordance with the interior and exterior boundaries of top opening 26. Thus, baffle plates 10 comprise an inner radiation seal 50 and an outer seal 52. For the purpose of mounting radiation seal 50 and outer seal 52 to furnace bottom 12, inner stub plates 54 and outer stub plates 56 are mounted around the periphery of top opening 26. The

stub plates

54 and 56 are spaced apart in confronting relationship and are fixed to furnace bottom 14 by fillet welds '58 and 59, respectively. It is preferable to fabricate scalloped edges on stub plates 56 in accordance with the finned walls of combustion chamber 18, such that fillet welds 59 form a gas tight closure Seal. Whereas in the case of stub plates 54, straight edges "are provided which are mounted on tubes 16 by means of the fillet Weld 58. By progressively inspecting FIGS. 1 and 2, it can be seen that radiation seal 50 and outer seal 52 include individual corrugated panels 60. The panels 60 are formed with a series of contours or corrugations 64 having a sinusoidal configuration Wtih a relatively fiat top edge border 66, two side edge borders 68 and a remaining bottom edge border 70 through which the corrugations 64 run.

The corrugations 64 are fabricated by explosive forming, which includes positioning shaped exposive charges in accordance with the preselected desired shape of corrugations 64. The charges are simultaneously detonated in a suitable medium to develop localized shock waves which are transmitted to the area on panels 60 which are adja cent to the charges. A more detailed description of the explosive forming method of fabrication is given in applicants copending application Ser. No. 447,709, filed on Apr. 13, 1965.

It is preferable to join the panels 60 into the generally rectangular configuration of outer seal 52 by welding together four of the panels 60 along the side edge borders 68. After this rectangular configuration is obtained, it is then possible to mount outer seal 52 onto the furnace bottom 12 by means of fillet welds 72 which are located at the junction between top edge border 66 and stub plates 56. The radiation seal 50, which must sustain temperatures in the neighborhood of 1800 F., is formed by mounting individual panels 60 on stub plates 54 by means of a nut and bolt assembly 74. It should be noted that the side edges 68 of radiation seal 50 need not be welded together as is the case of outer seal 52, since a gas tight closure is not required for radiation seal 50. In this manner, the radiation seal 50 is positioned within the receptacle chamber 28, spaced apart from the inner portion of side walls 24, and outer seal 52 is positioned outside of receptacle chamber 28, spaced apart from the outer portion of side Walls 24 with the outer seal 52 extending into cooling circuit 40 to form a gas tight seal.

The corrugated panel 60 shown in FIG. 3 must be capable of high temperature service, sudden temperature changes, and resisting corrosive conditions. It is preferable to first fabricate the corrugated panels 60 with the corrugations 64 by using the method of explosive forming, and panels 60 should then subsequently be oven tempered to reinstate corrosion resisting properties. By fabricating the bafile plates 60 in this manner, a solution is provided to the problem of panel cracking and distortion due to large temperature differentials between fixed edge 66 and free edge 70.

The following table is illustrative of bafile plates 60 fabricated by explosive forming:

Inner radiation seal 50 Type of material #304 stainless steel Thickness of plate (.120 inch) ga-uge 11 Depth of corrugations inches %1 Spacing of corrugations (center to center) do 4 Type of material Corten steel Thickness of plate (.120 inch) gauge 11 Depth of corrugations inches /a% Spacing of corrugations (center to center) do 4 From the foregoing, it can be appreciated that in accordance with the present invention the inner seal 50 forms a closure against radiation emanating from ash hopper 14 and outer seal 52 forms a gas tight closure between furnace bottom 12 and ash hopper 14. By fabrieating inner seal 50 and outer seal 52 from corrugated panels 60, it is possible to operate at relatively high temperatures and at a gradient of varying temperature increments along the length of side edge borders 68. Thus, the battle plates 10 can sustain massive heat transfer without material failure, since thermal expansion is absorbed by the corrugations 64.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. A seal in combination with a vertically disposed furnace bottom having a discharge opening and an ash hopper having a top opening spaced apart from said discharge opening, said ash hopper including a trough extending around the outer periphery of said hopper, relatively thick inner bafile plates positioned along the inner periphery of said discharge opening such that a closure is formed against radiation from said ash hopper, relatively thick outer bafile plates positioned along the outer periphery of said top opening and extending into said trough such that a gas tight closure is formed between said furnace bottom and ash hopper, said inner bafile plates and outer bafi'le plates being explosively formed with a plurality of elongated corrugations which are vertically disposed and substantially parallel to each other, the vertical axis of said discharge opening and the vertical axis of said ash hopper, whereby thermal expansion is absorbed by said corrugations.

2. A seal in combination with a vertically disposed furnace bottom having a discharge opening and an ash hopper having a top opening spaced apart from said discharge opening, said ash hopper including a trough extending around the outer periphery of said ash hopper, relatively thick baifie plates positioned along the outer periphery of said top opening and extending into said trough such that a gas tight closure is formed between said furnace bottom and ash hopper, said baffie plates being explosively formed with a plurality of elongated corrugations which are vertically disposed and substantially parallel to each other, the vertical axis of said furnace bottom and the vertical axis of said ash hopper, whereby thermal expansion is absorbed by said corrugations.

References Cited UNITED STATES PATENTS 801,148 10/1905 Leffer -166 1,991,704 2/1935 Schellhammer et a1. 126116 2,337,634 12/1943 Berry 110-465 3,228,362 1/1966 Jarvis 110-165 JAMES W. WESTI-LAVER, Primary Examiner.