US2992678A - Burner apparatus and controls therefor - Google Patents

Description

July 18, 1961 w. H. DA1LEY,JR 2,992,673

BURNER APPARATUS AND CONTROLS THEREFOR Filed Nov. 19, 1951 2 Sheets-Sheet 1 July 18, 1961 w. H. BAILEY, JR

BURNER APPARATUS AND CONTROLS TRRRRFOR Filed Nov. 19l 1951 2 Sheets-Sheet 2 ,o 1LT-R- INVENTOR la/J Dai/ey J5.

United States Patent G 2,992,678 BURNER APPARATUS AN D CONTROLS I THEREFOR William H. Dailey, Jr., near Toledo, Ohio, assgnor, by mesne assignments, to Midland-Ross Corporation, Cleveland, Ohio, a corporation of Ohio Filed Nov. 19, 1951, Ser. No. 257,019 Claims. (Cl. 158-119) This invention relates to burner apparatus and controls for burning fuel gas in furnaces such as soaking pit furnaces, and is designed to provide a burner which is adaptable to relative expansion of steel and refractory portions of the furnace without affecting the efciency thereof and which is much simplified yet most serviceable in its intended operation.

It is the object of this invention to provide a simple and economical burner and proportioning apparatus for supplying combustible gases to the burner port of a furnace.

An advantage of the invention is the provision of air flow uniformly distributed across the burner port section and which is virtually unaffected by the approach conditions of the component combustible gases. This advantage is attained by the particular arrangement of the co-operating components of the apparatus as shown in the drawings and described in the specification. Such feature is most desirable yet most diicult to attain in furnaces employing jet pumps as means for distributing the combustion air.

For a consideration of what I believe to be novel and my invention, attention is directed to ths specification and the drawing and concluding claims thereof.

In the drawing:

FIG. 1 is a diagrammatic representation of soaking pit furnace apparatus to which the invention is applied.

FIG. 2 is a sectional view of the burner generally illustrated in FIG. l.

FIG. 3 is a sectional view of the burner of FIG. 2 taken on line 3-3 thereof.

FIG. 4 is a sectional View of the burner of FIG. 2 taken on staggered line 4--4 thereof.

FIG. 5 is a sectional View of a gas metering device used with the burner of FIG. 2.

FIG. 6 is a sectional view of the device of FIG. 5 taken on line 6 6 thereof.

FIG. 7 is a sectional View of a detail of the burner of FIG. 2.

FIG. 8 is a schematic control diagram showing functional relationships of elements for burner controls.

FIG. 9 is a schematic diagram of the working apparatus diagrammatically shown in FIG. 8.

The soaking pit comprises a combined combustion and heating chamber 10 which is normally closed by a removable cover 11, the chamber being of a size to contain a plurality of steel ingots 12 indicated in outline by discontinuous lines. Heating ame enters the chamber 10 from a firing or burner port 13 whose inlet is coincident with the outlet of a burner 14 to which fuel is delivered by a supply pipe 15 having a control valve 16 and to which air for combustion is delivered by a duct 17 having a control valve 18'. Flue gas is vented from the chamber 1i? through an exhaust port 19. The heating unit thus far described is a single soaking pit furnace, or hole, and is customarily one of several units in a battery having a common llue gas exhaust manifold 21 and a common burner air distributing manifold 22.

The rate of fuel supply to the furnace chamber 10 will ordinarily be determined by means responsive to temperature by a radiation device as is well known, hence `not illustrated herein, said means being adapted to adjust `the ,fuel control valve 16 to maintain the desired furnace Patented July 18, '1961i ICC temperature. A predetermined ratio of fuel to air will ordinarily be delivered to the burner 14 by adjusting the air valve 18 by ratio control means 23 which is responsive to adjustment of the fuel ow to the burner. While the apparatus herein disclosed adjusts fuel flow responsive to chamber temperature and adjusts air How to maintain a fuel to air ratio, the apparatus is equally applicable to control of air responsive to temperature in the chamber 10 and corresponding adjustment of fuel iiow to maintain the desired fuel to air ratio.

Air may be delivered to the air manifold 22 by any conventional means, and may be preheated by a recuperator as herein shown. Air is drawn into a recuperator 24 through entry port 25 and is heated in the recuperator before passing into the plenum chamber 26 of a jet pump 27 from which it is inspirated by a jet of air from a compressor 30, pipe 31 and jet nozzle 32 and delivered by manifold 22 and pipe 17 to the burner 14.

Flue gases from the chamber 10 pass through the exhaust port 19 to the exhaust manifold 21, through the recuperator 24 wherein some of its heat is transferred to the air drawn therethrough, and thence through exhaust duct 34 to an ejector 35 where a jet of air 4from the compressor 30, pipe 36 and a nozzle 37 inspirates exhaust flue gases from the duct 34 and delivers them through a venturi stack 38 of the ejector 35.

The burner port is formed in a cast ceramic burner block 41 which is supported on the furnace lining 42 and upon relative expansion of the lining with the steel furnace binding 4t), which may be as much as four inches from cold to operating temperature, the furnace lining and the burner block move as a unit with respect to the binding. A flanged frame 43 supports the burner block and moves therewith and is retained next adjacent the burner and the steel binding, or shell, 40 of the furnace by a retainer track or guide 44 welded thereto. An annular refractory ring 45 is retained in the pit binding between the burner block 41 and the burner 14, the ring being thicker at the top than at the bottom to allow the burner 14 to be inclined from the horizontal. An extended sleeve portion 46 of the furnace binding 40 encloses the rings 45 and terminates in a ange 47 to which the burner 14 -is secured. As the refractory ylining 42 of the furnace expands with relation to the steel binding 40 thereof, the ring 45 and the burner 14 remain secured to the steel while the burner block moves with the refractory, the flange frame 43 of the burner block being retained next adjacent the steel binding by the track 44 wherein it moves. The lower portion of the burner block is stepped so that the brick of the furnace lining therebelow cannot shift to open a path below the monolithic burner block through which the heat of the chamber 10 may see the steel binding, and by radiation over-heat it. A diiiculty inherent in prior designs in that after periods of use passages would open between the burner block and the furnace lining, or between the block `or lining and the furnace binding or burner, thus allowing combustion of gases therebetween which shortly burned out the metal binding or burner wall, has of course been overcome by this design in that the burner block is adapted to move with the furnace lining, yet the guide or track 44 coacts with the flange 47 of the burner block 41 to seal off passage of combustion gases next adjacent the metal wall of the burner and furnace, through which passage gases would ordinarily be induced to flow by flow of gases through the burner port, or tunnel.

The burner 14 comprises a steel box 50 forming a plenum chamber for receiving air from the pipe 17, the box being refractory lined, and a venturi tube 51 is supported with its inlet in the said plenum chamber and its outlet coincident with the core of the annular ring 45. A cluster of gas delivery pipes 52, four being shown, extend from the burner port 13 through the venturi tube 51 and through the air plenum chamber to a gas chamber formed by a gas receiving box 53. A sight tube 54 in the box 53 extends through the box and is aligned with the core of the pipes 52 in such a manner that access is had to the pressure of the air plenum chamber in the burner 14, and sight is had through the tube 54 and the core of the cluster of gas pipes, through the center of spacers 55. The tube 54 is also in a convenient location for an oil tube if it is desired to burn oil in the burner as during periods when gas is unavailable. It would, of course, be unnecessary to remove the gas tubes 52 to burn oil in this burner.

The burner 14 is adapted to receive fuel gas through a side inlet S6 to the gas receiving box 53. Fuel is delivered thereto by a fuel supply pipe '15 which includes a fuel metering device 57. This device is made of a shell 58 which is easily fabricated by welding of conventional pipe shapes such as a pipe T, reducers and the like. A shaft 60 extends through the shell and is supported at the gas outlet end by a web 61 and at the other end of the shaft by a flange 62 and packing gland 63. A tapered sleeve 64 on the shaft 60 coacts with the shell 58 to form therebetween an annular venturi gas passage having a vena contracta between the tapered sleeve and a straight pipe portion of the shell. Thus by axial displacement of -the shaft 60 the area of the annular vena contracta may be adjusted as desired to compensate for preheat temperature of combustion air, character of the fuel gas, and the like. An indicator disc 65 secured to the shaft may be used with a suitably inscribed scale 66 secured to the shell 58 to indicate relative adjustment of the sleeve 64 and the shell 58.

- For purposes of control of the ratio of flows of fuel and air through the burner, a single diaphragm control device 70 is utilized, being responsive to air flow through a pressure tap 71 at the throat of the venturi tube 51, through pipe 7l2 and to flow of gas through a pressure tap 73 at the throat, or vena contracta, of the fuel metering device 57 through pipe 74. The device 23 is a pneumatic servo-mechanism operated by high pressure air supplied thereto through pipe 75, responsive to the air and fuel pressure impulses through pipes 72 and 74, and adapted to move air valve 18 through suitable mechanical linkage elements generally indicated at 76.

The air pressure of pipe 72 loads one side of a diaphragm 78 in the control device 23, and lthe gas pressure pipe 74 loads the other side of the diaphragm, an adjustable cantilever spring 77 being used to bias the diaphragm to balance at the desired difference of pressures of air and fuel. The diaphragm 78 is mechanically connected to the piston 80 of an air control valve 81 to which high pressure air is supplied through pipe 75, and the piston is adapted to control flow of high pressure air to a pneumatic cylinder 85 through pipes 82 and 83 to the respective sides of the piston 86 thereof, whereby to control turning of a shaft 84 which, in turn, through linkage mechanism 76 moves the air valve `18 as desired to control flow of air to the burner. With valve 87 opened, the piston 86 will be free to move, and the air valve 18 may be manually adjusted.

The use of a single pressure impulse in the air and gas metering systems stems from the peculiar design of burner herein utilized. It is remembered that measurement of gas flow through an orifice or a venturi is made possible by pressure relationships known to exist therein. For example, in a venturi there is an initial pressure drop upon entering the venturi, with a minimum pressure at the throat, a vena contracta, and a subsequent recovery of pressure from the throat to the end of the diffuser section of the venturi resulting in an overall loss of pressure in the gas passing through the venturi. While it is customary to measure the initial pressure drop because it is the greatest, the recovery is also proportioned to flow,

and is used here as a measure of flow. This gives the added advantage in this case of utilizing the pressure in the combustion chamber 10 as a common pressure in both the air and the gas streams; since these pressures may be considered equal, the vena contracta pressures can be used for measure of comparative flows of air and gas.

The burner and controls therefor are well adapted for use on furnaces wherein the heating chamber is also the combustion chamber, the pressure of which is a common downstream pressure in the metering devices, hence allowing use of a single diaphragm ratio control. The burner 14 is inclined at an angle 49 to allow the burner block to be suiliciently below the cover to make a stable cover support structure, yet avoid impingment upon the work by the burner llames. The burner and burner block structure is well adapted for use in lfurnaces where the lining thereof moves, due to expansion, with respect to the metal lining thereof.

l claim:

l. Combustion apparatus for a soaking pit furnace comprising: a burner port adapted to be located in a Wall of the furnace; a first venturi tube adapted to be in substantially axial alignment with said burner port and having its discharge end substantially coincident with the entrance of said por-t; a cluster of tubes extending through the vena contracta of said venturi tube and having their discharge ends substantially coincident with the discharge end of said venturi tube; pipe means for suppyling combustible fuel to said tubes; duct means for supplying combustion air to said venturi tube; a second venturi tube in said pipe means through which combustible fuel passes before entering said tubes; a valve located in one of said pipe means and duct means for controlling flow therein; a housing containing a exible diaphragm; means for connecting the vena contracta of said first venturi tube to said housing on one side of said diaphragm and the vena contracta of said second venturi tube to said housing on the other side of said diaphragm whereby the pressures of said vena contractae are transmitted to opposite sides of said diaphragm, said means comprising a single pressure tap for each of said rst and second venturi tubes; and means operatively connecting said diaphragm to said valve to open and close said valve in response to movement of said diaphragm in a manner tending to maintain the ratio of the pressures at the vena contractae constant.

2. Combustion apparatus for` a soaking pit furnace comprising: a burner port adapted to be located in a wall of the furnace; a first venturi tube adapted to be aligned with said burner port and having its discharge end substantially coincident with the entrance of said port; a cluster of tubes extending into said venturi tube and having their discharge ends substantially coincident with the discharge end of said venturi tube; pipe means for supplying combustible fuel to said tubes; duct means for supplying combustion air to said venturi tube; a second venturi tube in said pipe means through which combustible fuel passes before entering said tubes; a valve located in one of said pipe means and duct means for controlling flow therein; a housing containing a flexible diaphragm; means for connecting the vena contracta of said first venturi tube to said housing on one side of said diaphragm and the vena contracta of said second venturi tube to said housing on the other side of said diaphragm whereby the pressures at said vena contractae are transmitted to opposite sides of said diaphragm; a source of high pressure air; a cylinder containing a piston operatively connected to said valve for opening and closing the same; means for directing air from said source to either end of said cylinder; and mechanical connecting means connecting said diaphragm to the directing means to direct air to one end of said cylinder when the pressure is greater on one side of said diaphragm and to direct air to the other end of said 'cylinder when the pressure is greater on the other side of said diaphragm, whereby said valve will be opened and closed by said piston in a manner tending to maintain the ratio of the combustion air and fuel constant.

3. Combustion apparatus for a soaking pit furnace comprising: a burner port adapted to be located in a wall of the furnace; a first restrictive passage adapted to be aligned with said burner port and having its discharge end substantially coincident with the entrance of said port; a cluster of tubes extending through the throat of said passage and having their discharge ends substantially coincident with the discharge end of said passage; pipe means for supplying combustible fuel to said tubes; duct means for supplying combustion air to said restrictive passage; a second restrictive passage in said pipe means through which combustible fuel passes before entering said tubes; a valve located in one of said pipe means and duct means for controlling ow therein; a housing containing a flexible diaphragm; means for connecting the throat of said first passage to said housing on one side of said diaphragm and the throat of said second passage to said housing on the other side of said diaphragm whereby the pressures at said throats are transmitted to opposite sides of said diaphragm; a source of high pressure air; a cylinder containing a piston operatively connected to said valve for opening and closing the same; and means operatively connected to said diaphragm for directing high pressure air from said source to either end of said cylinder to actuate said piston and open and close said valve in a manner tending to maintain a constant ratio of the combustion air and fuel.

4. `Combustion apparatus for a soaking pit furnace comprising: a burner port adapted to be located in a Wall of the furnace; a first venturi tube adapted to be aligned with said burneiport and having its discharge end substantially coincident with the entrance of said port; a cluster of tubes extending into said venturi tube and having their discharge ends substantially coincident with the discharge end of said venturi tube; pipe means for supplying combustible fuel to said tubes; duct means for supplying combustion air to said venturi tube; a second venturi tube in said pipe means through which combustible fuel passes before entering said tube; a valve located in one of said pipe means and duct means for controlling ilow therein; a housing containing a flexible diaphragm; means for connecting the vena contracta of said first venturi tube to said housing on one side of said diaphragm and the vena contracta of said second venturi tube to said housing on the other side of said diaphragm whereby the pressures at said vena contractae are transmitted to opposite sides of said diaphragm; a source of high pressure air; and means responsive to said diaphragm and co-acting with said source of air for opening and closing said valve to maintain a constant ratio of the combustible air and gas.

5. In combination with a furnace having at least one burner port located in one of its walls, apparatus for supplying fuel and air to said burner port which comprises: means forming a flue gas passage for venting ue gas from said furnace, a recuperator disposed in the ue gas passage and having an air heating duct therethrough; air supply pipes for supplying air to each of the burner ports; an air manifold for supplying air to the air supply pipes; an air conduit for conducting air from the air heating duct of the recuperator to the manifold; a jet pump in the air conduit for drawing air from the recuperator air heating duct and delivering it to the manifold; a nozzle forming part of the jet pump :for discharging motive fluid into the air conduit; means for supplying motive fluid to the nozzle; burner means for each of said ports having a rst venturi passage through which the combustion air passes before discharging into said port; a second venturi passage through which the fuel gas passes before discharging into said port,` said iirst and second venturi passages having their discharge ends substantially coincident with the entrance of said burner port; a first pressure tap for obtaining a pressure impulse at the vena-contracta of said first venturi passage, a second pressure tap for obtaining a pressure impulse at the vena-contracta of said second venturi passage, rst valve means adapted to control flow to one of said venturi passages; second valve means adapted to control ilow to the other of said venturi passages, and single diaphragm means responsive to said pressure impulses on opposite sides of the diaphragm of said means for adjusting said second valve means to vary the flow through said other venturi passage to maintain a desired ratio of ows through said venturi passages.

References Cited in the tile of this patent UNITED STATES PATENTS 1,264,961 Moyer May 7, 1918 1,522,907 Price Jan. 13, 1925 1,558,529 Wunsch Oct. 27, 1925 1,573,079 McKee Feb. 16, 1926 1,721,381 Ellis July 16, 1929 1,785,583 Hawke Dec. 16, 1930 1,953,590 Cone Apr. 3, 1934 2,003,226 Weller May 28, 1935 2,0251696 Brancke Dec. 24, 1935 2,147,568 Barber Feb. 14, 1939 2,193,240 Schmidt Mar. 12, 1940 2,222,822 Nordensson Nov. 26, 1940 2,262,609 Keller Nov. l1, 1941 2,353,865 Armstrong July 18, 1944 2,365,945 Ferguson Dec. 26, 1944 2,571,336 Buckholdt Oct. 16, 1951 2,675,820 Harrison Apr. 20, 1954 FOREIGN PATENTS 982,338 France Ian. 24, 1951

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