US3212558A

US3212558A - Industrial burner

Info

Publication number: US3212558A
Application number: US405012A
Authority: US
Inventors: Williams John Roger
Original assignee: Selas Corp of America
Current assignee: Selas Corp of America
Priority date: 1964-10-09
Filing date: 1964-10-09
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19

Description

Oct. 19, 1965 J. R. wLLAMs INDUSTRIAL BURNER 2 Sheets-Sheet 1 Original Filed Aug. 14. 1961 INVENTOR.

JOHN ROGER WILLIAMS ATTORNEY.

1965 J. R. WlLLlAMS 3,2l2,558

INDUSTRIAL BURNER 2 Sheets-Sheet 2 Original Filed Aug. 14. 1961 INVENTR. JOHN ROGER wLLAMs /(as 4,44 %m ATTORNEY.

United States Patent O 3,212,558 INDUSTRIAL BURNER John Roger Williams, Ambler, Pa., assignor to Selas Corporation of America, Dresher, Pa., a corporation of Pennsylvania Continuation of abandoned application Ser. No. 131,379, Aug. 14, 1961. This application Oct. 9, 1964, Ser. No.

10 Claims. (Cl. 158-108) This is a continuation of application Serial No. 131,379, filed August 14,1961, now abandoned.

The present invention relates to burners and more particularly to burners for industrial purposes in which the burner is provided with recuperative means to preheat the air being supplied thereto.

Generally speaking, when recuperation is necessary, air supplied to a plurality of burners in an industrial furnace is preheated at a central point and piped individually to the burners. This requires a large amount of eX- pensive, high temperature piping between the recuperator and each burner.

It is an object of this invention to provide a high capacity industrial burner which has a recuperator built into it.

It is a further object of the nvention to provide a furnace burner in which hot products of combustion from the furnace are directly circulated to preheat the air for combustion as it is flowing through the burner to the furnace.

The burner is so designed that there is provided a large heat exchange surface in a relatively small area, and so that various of the parts can move relative to each other as required by differential thermal expnsion.

The various features of novelty which characterize my invention are pointed out with particularly in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is' a section through one form of the burner,

FIG. 2 is a view from the left of FIG. 1, and

FIG. 3 is a section through another form of the burner.

Referring to FIG. 1 there is shown at 1 a furnace wall in which the burner is inserted and of which the front of the burner forms a part. The portion of the burner in the furnace wall includes a refractory cup block 2 that has a cup-shaped depression 3 formed in the surface 2A thereof facing the furnace interior. surrounding this cup block to form the remainder of the burner block there is provided a ring comprised of a plurality of segments 4 that are cemented to the cup block and to each other. These segments are so formed that passages 5 extend through the block to the rear face thereof. It is noted that both the cup block and the segments 4 are provided with ridges 6 so that they will be held in axial alignment, and so that the entire burner block will be held accurately in position in the refractory of the furnace wall.

Extending rearwardly from the composite burner block through the remainder of the furnace wall there is a cylindrical refractory structure including two

cylinders

7 and 8. These cylinders are cemented together and are held in position by means of a metal casing 9 that is bolted to the furnace casing 11. Cylinder 7 is attached with a gas tight seal to the back of the burner block. Cylinder 8 is provided with an eXhaust opening 12 that connects with a stack 13. The back of cylinder 8 is closed by a refractory disc 14 that is cemented in place in the end 3,2l2,558 Patented Oct. 19, 1965 of the cylinder, but which is also held in position by means of a metal cover 15.

Cylinders

7 and 8 form a recuperator chamber 16 with the back surface 2B of block 2 and disc 14 .as the end walls thereof. In this chamber are located the gas and air supply pipes through which fuel and air are supplied to the burner block.

The center of the cup block 2 is provided with an opening 17 that is concentric With the base of depression 3. A sleeve 18, which has an enlargement 19 on its rear end, is received in opening 17. Fastened to the rear end of the enlargement is a tube 21 that extends rearwardly through an opening in disc 14 and cover 15. The right end of this tube is sealed in gas tight fashion with respect to the cover by a seal ring 22 which will permit movement between the tube and the cover. A fuel and air distributo' tip in the form of element 23 is snugly received in the sleeve 18. This element is provided with a plurality of radially extending gas passages 24 that are at such an angle to the axis of the member that they Will discharge substantially parallel to the base of the depression 3. The exterior of element 23 is provided with a plurality of air passages 25 that are formed by helically extending ribs 26 projecting from the outer surface of element 23. Fuel gas is delivered to the passages 24 by means of a pipe 27, which pipe has a flange 28 extending radially from it for a purpose to be described. The right end of this pipe is threaded to a cap 29, which in turn is bolted to the cover 15. In this fashion the element 18 is positioned axially in opening 17. It is noted that a ring 31 is placed in the outer end of tube 21 to limit the movement of this tube with respect to pipe 27 and position sleeve 18 axially with respect to element 23.

Air is supplied to passages 25 by means of a helical tube 32 which surrounds the tube 21. This tube is made of a high temperature alloy, and has a relatively thin wall. The left end of tube 32 is fastened to the enlargement 19 so that the tube is in communication with the interior thereof. The outer or right end of tube 32 is indicated at 33 as extending into a cap 35 to which the air connection from a suitable source of supply can be made. A seal 34 is provided between end 33 and cap 35 so that the tube can move relative thereto. If it is desired, an insulating refractory sleeve 36 can be placed around tube 21 inside the helix of tube 32 to help, along with the space between pipe 27 and tube 21, to insulate pipe 27 from the heat. It is noted that the stack 13 is somewhat of the shape of a venturi, and is provided at or near its throat with the discharge nozzzle of a pipe 37 for air under pressure.

In the operation of the burner, gas and air in suitable proportion, as determined by an ordinary ratio controller, will be supplied respectively through pipe 27 and tube 32 to the

passages

24 and 25. The gas is discharged in a radial direction while the air issues -axially from the helical passages 25. Because of the action of centrifugal force on the air, it will move outwardly along the surface of cup 3 to mix with the gas flow along the surface, where they are ignited and burned. The base of the cup 3 is provided with a rdge 3B as best shown in the drawing, which creates enough turbulence in the flowing gas and air to produce a piloting action which will root the flames adjacent to the discharge ends of the gas and air ports. The burner will operate to heat the surface of the cup to incandescence and thereby direct radiant heat into the furnace. Heat is also produced by convection from the hot products of combustion.

In most furnaces there is some slight furnace pressure because of expansion of the gases of combustion. Such pres-sure will cause some of the hot products of combustion to flow backwardly through passages 5 into the chamber 16, to be discharged through opening 12. These hot products of combustion flowing through the chamber 16 hour with an air-gas ratio of 10 to 1.

will serve to heat tube 32 and thereby preheat the air. It is noted that the right ends of openngs 5 are oifset as shown at 38, so that direct radiation from the furnace will not impinge upon the front end of the enlargement 19 or upon the tube.

Means is provided to prevent products of combustion from short circuiting or flowing directly from cup 3 to openings 5 without circulating through the furnace chamber. It will be noted, particularly in FIG. 1, that those portions of the cup radially inwardly of openings 5 termnate in an axially extending portion 3A, while the remainder of the cup edge is a continuation of the cup surface as shown in the upper edge of the cup in FIG. 1. Thus the gases of combustion are discharged substantially axially past openings 5, while they move radially into the furnace at other points on the cup circumference. In this manner gases will be positively directed out into the heating chamber of the furnace prior to the time some of them are withdrawn for preheating purposes. This same arrangement can be used in the embodiment of FIG. 3, described below, if it is so desi red.

A burner of the present type having a cup diameter of approximately 11 /2" can be supplied with 750 cubic feet of natural gas to produce about 750,000 B.t.u. per This mixture of gas and air will burn to produce hot products of combustion which are drawn back through opeings 5 at a temperature of about 3000 F. If approximately one third of the products of combustion are withdrawn through the space 16, they will heat the fixture 19 and tube 32 immediately adjacent to the exit :of openings 5 to a ternperature of about 1950 F., and will be discharged through opening 13 at approximately 1200 F. These hot products of combustion circulating around tube 32 will serve to preheat `the air in the tube to approximately 1000 F., thus utilizing a good deal of heat that would normally be lost through the exhaust products of combustion from the furnace, and thereby helping to increase the temperature produced by the burner. It is noted that the gas and air flowing through element 23 will have a cooling effect on it, so that this element will not have its temperature raised above about 1600 F., which is well within the working limits of a high temperature alloy.

The various elements of the fuel and air distrbuting system in chamber 16 will be heated varying amounts to cause a difierential expansion of these elements as a result of the temperature variations. Seal 22 permits tube 21 to eX-pand and contract without placing any strain upon the various joints, and seal 34 will permit helical tube 32 to expand and contract so that this tube will not be placed under any undue strain. The Construction of the burner will permit a .large pick up of heat to the incoming air that would otherwise be lost, and the construction is such that the various parts of the burner will not be subjected to undue strain as the burner is heated and cooled. Sleeve 36 protects somewhat the gas pipe 27 from the intense heat in space 16, and thereby helps to prevent cracking of the gas prior to the time it i-s discharged into the furnace. It is noted that flange 28, in effect, creates asmall chamber in the front portion of fixture 19, -so that the hot air will not flow back along the pipe through which the gas is being introduced to the burner.

The embodiment of the invention shown in FIG. 3 of the drawing is essentially the same as that prevously described, except for the manner in which the air flows through the coil in the recuperator chamber 16. In this case the air is brought first to the front of chamber 16 and moves backwardly through the preheating coil. Referring to the drawing it will be seen that there is provided a second sleeve 41 which is concentric with sleeve ,21, and extends throughout the length of chamber 16.

The front end of this sleeve is provided with a partition 42 to form an annular chamber 43. Air for combustion is brought in through cap 35 to a tube 44 which extends between this cap and chamber 43. A helical tube 45 extends between the chamber 43 and the rear end of sleeve 41 with which it is connected, so that air can flow from chamber 43 through the tube and into the space between

sleeves

21 and 41. From here the air travels forward through openings 46 in sleeve 21 to the distributing element 23. It will be noted that the rear end of sleeve 41 is received in a slidable seal 47, so that this sleeve can expand and contract with respect to the rest of the burner in the same manner that tube 44 can slide in seal 34 and tube 21 can slide in seal 22.

In the operation of this embodiment of the invention, the cool air is first brought to the front portion of space 16 where the exhaust gases are hottest. The air then flows rearwardly through coil 45 as it is being preheated, and then back to the passages 25 to be discharged in the burner. This arrangement of the parts means that the coldest air is in heat exchange relation with the hottest gases. Therefore, the metal parts will not be heated to the extent that they Were in the previous embodiment. Thus, for some applications, it will be possible to use a lower alloy steel than is required with the embodiment of FIG. 1. In either event, however, the air is raised to substantially the same temperature.

From the above description it will be seen that I have provided a burner which includes as an integral part thereof provisions for preheating the air prior to the time it is combined with the gas and ignited. The arrangement is such that a relatively large area is provided for contact between the hot gases of combustion and the cold combustion air, thus making it possible to obtain a high degree of preheat in a relatively small space. In addition, the parts are so constructed and arranged that those elements of the burner which are subjected to temperature dilferentials, and which are heated and cooled most during the operation of the burner, can move relative to each other as these temperature changes take place. Thus the various parts are not subjected to severe strains which Would tend to cause them to separate from each other. The burner is simple in Construction and is compact. After the burner block has been placed in the furnace wall, the other parts can be moved as a unit into position, so that when casing 9 is bolted to the furnace casing 11, the burner is completely assembled and ready for operation. This Construction permits the preheat obtained from each burner to be varied independently by varying the aspirating air introduced into stack 13 through pipe 37 so that the proper amount of preheat can be obtained. The arrangement, also does away with a central recuperator and the complicated piping that is necessary to bring preheated air to a plurality of burners located at various points in a furnace.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit and scope of the invention set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. An industrial burner comprising a refractory part having a face forming an exposed portion of a furnace wall, 'said face having a cup-shaped depression therein and a central opening at the base of said depression, an element received in said opening having a first set of passages through which fuel is discharged across the surface of said depression, and a second set of passages through which combustion air is discharged across the surface of said depression, a pipe connected to said first set of passages extending rearwardly from :said element through which fuel is supplied thereto, a tube through which air is supplied adjacent to said pipe, means surrounding said pipe adjacent to said element forming a connection between said second set of passages and one end of said tube, means forming a chamber surrounding said tube, said face being provided with a plurality of openings around said central opening beyond the edge of said depression and extending from the exposed portion of the furnace wall to said chamber, and means to cause furnace gases to pass through said plurality of openings into said chamber and thereby preheat the air passing through said tube.

2. The combination of claim 1 including means to insulate said pipe from said chamber.

3. An industrial burner comprising a burner block adapted to be placed in a furnace wall and having a face with a cup-shaped depression therein forming an exposed portion of the wall, structure forming a chamber back of and attached to said block, said block being provided with an axial opening in said face at the base of said depression one end of which terminates in said chamber, an element having a plurality of gas passages and a plurality of air passages received in said opening, said passages being directed to discharge gas and air respectively across the surface of said depression, a pipe communicating with said gas passages, said pipe extending through said chamber, a tube located in said chamber and adjacent to said pipe, one end of said tube extending beyond said chamber adjacent to said pipe, means connecting the other end of said tube to the air passages in said element, said burner block face being provided with a plurality of openings surrounding said first mentioned opening beyond the edge of said depression and extending into said chamber adjacent to said other end of said tube, and means to draw furnace gases through said last mentioned openings and chamber, said gases circulating around said tube.

4. An industrial burner comprising a burner block having a face adapted to form part of a furnace wall, said face having a central opening extending therethrough and a plurality of openings around said central opening, means attached to said block forming a recuperator chamber having a back wall away from the face of said block, each of said openings extending into said chamber, an element received in said central opening having fuel passages and air passages directed to discharge beyond the face of said block, a fuel supply pipe in said chamber with one end communicating with said fuel passages and the other end extending through said wall, a helical tube surrounding said pipe, means eXtending through said wall connected to supply combustion air to said tube, means connecting the other end of said tube to said air passages, and means to draw furnace gases through said plurality of openings into and through said chamber, said extending means being connected to the end of said tube adjacent to said wall and said means connecting the other end of 'said tube including an annular chamber surrounding said pipe and inside the helx of said tube.

5. The combination of claim 4 including a slidable seal between said extending means and said wall.

6. An industrial burner comprising ceramic structure in the form of a burner block having one surface adapted to form a portion of a furnace wall and an opposite surface, said ceramic structure also forming a chamber with said opposite surface as one wall thereof and an opposite wall, said block being provided with a central opening and a plurality of openings surrounding said central opening, said openings extending between said surfaces and terminating in said chamber, an element received in said central opening provided with fuel passages and air passages with said passages directed toward said one surface and discharging through the furnace wall, a fuel pipe extending through said opposite wall into said chamber to a position adjacent to said element, means connecting said pipe with said fuel passages, a sleeve surrounding and spaced from said pipe from said opposite wall to a position adjacent to said opposite surface of said block to protect said pipe, a hollow part surrounding said pipe and connecting the interior of said sleeve with said air passages, a coiled tube in said chamber surrounding and spaced from said sleeve, a member through which combustion air is supplied extending through said opposite wall and being connected to one end of said tube, the other end of said tube terminating in said hollow part and communicating with the interior of said sleeve, and means to apply a reduced pressure to said chamber adjacent to said back wall whereby furnace gases will be drawn through said plurality of openings from in front of said surface, around the tube in said chamber and be exhausted therefrom.

7. The combination of claim 6 in which the end of said tube communicating with said sleeve 'is adjacent to said opposite surface, and means surrounding said pipe inside said sleeve between the location where said sleeve and tube are in communication and said opposite wall to retard the flow of air into said sleeve.

8. The combination of claim 7 including insulating material surrounding said sleeve and within and spaced from said tube.

9. The combination of claim 6 in which said member through which combustion air fiows is connected to the end of said tube adjacent to said opposite surface, means connecting the end of said tube adjacent to said opposite wall with structure forming an annular passage surrounding said sleeve, and means connecting said annular passage with the interior of said sleeve.

-10. An industrial burner comprising a ceramic structure in a furnace wall and having a face forming an exposed portion of said wall, said face being provided with a cup-shaped depression, means forming a chamber back of and connected to said structure, said structure being provided with an opening extending therethrough from the base of said depression to said chamber, an element having a plurality of gas passages and a plurality of air passages received in said opening, said passages being directed to discharge gas and air, respectively, across the surface of said depression, a pipe communicating with said gas passages, said pipe extending through said chamber, means in said chamber and adjacent to said pipe forming an el-ongtated path for combustion air, a part through which combustion air is supplied to one end of said means, means connecting the other end of said means in said chamber to the air passages -in said element, said structure also being provided with a plurality of openings spaced from said first mentioned opening and beyond the edge of said depression extending from the face of said furnace wall into said chamber adjacent to said other end of said means in said chamber, and means to draw furnace gases through said last mentioned openings into and through said chamber.

No references cited.

JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L.' MATTESON, JR., Examner.

Claims

1. AN INDUSTRIAL BURNER COMPRISING A REFRACTORY PART HHAVING A FACE FORMING AN EXPOSED PORTION OF A FURNACE WALL, SAID FACE HAVING A CUP-SHAPED DEPRESSION THEREIN AND A CENTRAL OPENING AT THE BASE OF SAID DEPRESSION, AN ELEMENT RECEIVED IN SAID OPENING HAVING A FIRST SET OF PASSAGES THROUGH WHICH FUEL IS DISCHARGED ACROSS THE SURFACE OF SAID DEPRESSION, AND A SECOND SET OF PASSAGES THROUGH WHICH COMBUSTION AIR IS DISCHARGED ACROSS THE SURFACE OF SAID DEPRESSION, A PIPE CONNECTED TO SAID FIRST SET OF PASSAGES EXTENDING REARWARDLY FROM SAID ELEMENT THROUGH WHICH FUEL IS SUPPLIED THERETO, A TUBE THROUGH WHICH AIR IS SUPPLIED ADJACENT TO SAID PIPE, MEANS SURROUNDING SAID PIPE ADJACENT TO SAID ELEMENT FORMING A CONNECTION BETWEEN SAID SECOND SET OF PASSAGES AND ONE END OF SAID TUBE, MEANS FORMING A CHAMBER SURROUNDING SAID TUBE, SAID FACE BEING PROVIDED WITH A PLURALITY OF OPENINGS AROUND SAID CENTRAL OPENING BEYOND THE EDGE OF SAID DEPRESSION AND EXTENDING FROM THE EXPOSED PORTION OF THE FURNACE WALL TO SAID CHAMBER, AND MEANS TO CAUSE FURNACE WALL TO SAID CHAMBER, AND MEANS TO OPENINGS INTO SAID CHAMBER AND THEREBY PREHEAT THE AIR PASSING THROUGH THE TUBE.