US2507554A - Gas burner for coke ovens - Google Patents

Description

y 1950 J. VAN ACKEREN GAS BURNER FOR COKE OVENS 2 Sheets-She et l Filed Aug. 14, 1945 INVENTOR Josgpw vmv flcKgRE/V.

ATTORNEY May 16, 1950 J. VAN ACYKEREN GAS BURNER FOR com: OVENS 2 Sheets-Sheet 2 Filed 14, 1945 INVENTOR Jose PH vmv 14ers RE/V.

ATTORNEY Patented May 16, 1950 GAS BURNER FOR COKE OVENS Joseph van Ackeren, Aspinwall, Pa., assignor to Koppers Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application August 14, 1945, Serial No. 610,692

3 Claims. I

This invention relates to gas burners. More particularly the invention relates to gas burners which are mounted in the refractory structure of a coke oven battery to heat the coke ovens.

Two types of gas are commonly employed for heating coke ovens. One gas is a coke oven gas which has a heating value of 550 to 600 B. t. u.s per cubic foot, while the other gas is a blast furnace gas which has a heating value of '75 to 90 B. t. u.s per cubic foot. The coke oven gas will burn with a short, hot flame with preheated air while the blast furnace gas burns with a long comparatively low temperature flame.

It is customary to dilute coke oven gas with waste flue gas to provide a mixture having a heating value of from 250 to 300 B. t. u.s per cubic foot. This mixture will burn with a long comparatively high temperature flame, and provides an effective medium by which the oven can be uniformly heated throughout.

With a blast furnace gas having a heating value of-from 90 to 100 B. t. u.s per cubic foot an effective uniform heating of the oven may be carried out by preheating both the air and gas prior to combustion. Blast furnace gas having a heating value below 90 B. t. u.s per cubic foot is generally not satisfactory for heating coke ovens and therefore coke oven gas is generally mixed with the blast furnace gas to form a mixture for heating the coke ovens. Attempts have been made to mix coke oven gas directly with the blast furnace gas before sending the mixture through a regenerator to be preheated before combustion, but' such practice has not been found practicable because the coke gas is cracked in the regenerators and deposits carbon in the checker brick of the regenerator.- This carbon is burned on the reverse cycle of the regenerator and passes out to the waste gas flue. Thus the higher B. t. u. value of the coke oven gas is lost. It has been found satisfactory to mix coke oven gas with a blast furnace gas-air mixture at the mouth of the burner in the bottom of the combustion flues at the sides of the oven.

The mixing tube and burner nozzle for burning coke oven or rich gas passes through a heated wall adjacent a regenerator to conduct the gas to the combustion fiues. The mixing tube is maintained at such a high temperature that if straight coke oven gas is passed through the tube at a low Velocity the gas will crack and clog the tube with carbon. To overcome this cracking, waste flue gas is mixed with the rich gas to speed up the gas velocity and to provide a diluted mixture which will not crack.

- erwise the burner mixer will not properly function to proportion the rich gas with the waste gas.

The Venturi throat and mixtng tube of the gas burner are formed in refractory shapes, which make up the regenerator walls. The regenerator walls undergo a comparatively large expansion when the oven and regenerators are being heated from a cold condition to the operating temperature. The burner refractory shapes accordingly move with the expanding regenerator walls. It is important therefore that the construction and arrangement of the inspirating nozzle and Venturi throat of the burner shall maintain their fixed desired position with relation to one another regardless of the expansion and contraction of the refractory walls and the movement of refractory burner shapes along with the regenerator walls.

The primary object of the present invention is to provide an aspirating burner for coke ovens in which the measuring parts of the burner will be maintained in their proper relative position when the oven structure moves due to expansion and contraction under varying conditions of heat.

A further object of the invention is to provide an aspirating burner built into and forming parts of the oven structure that is subject to expansion and contraction by which the parts of the aspirating burner will maintain their same relative gas measuring position as the oven parts expand and contract.

With these and other objects in view the invention consists in the improved gas burner hereinafter described and particularly defined in the appended claims.

The various features of the invention are illustrated in the accompanying drawing in which:

Figure 1 is a vertical sectional view of a part of an underjet coke oven battery illustrating the mounting in the furnace structure of a gas burner embodying the preferred form of the invention;

Figure 2 is a vertical sectional view of the furnace and burners of Figure 1 taken at right angles to the section of Figure 1; and

Figure 3 is an enlarged detail view in vertical section showing the mounting of the burners for heating flues at the opposite sides of a coke oven.

Referring to the drawings, in Figure 1, are illustrated coke ovens 18 on opposite sides of which are mounted heating flues l2 and I4. The heating flues and coke ovens are separated by refractory walls and below the coke ovens and flues are regenerators i6, i8, 28 and 22. The regenerators are fllled with checker brick and the walls of the regenerators are of refractory materials, preferably a high temperature silica refractory.

The heating of the coke ovens is a continuous process which is carried out in two parts. In the flrst half of the heating cycle air and fuel gas are introduced into the bottom of a heating flue, for example. l2. The products of combustion then pass up through the flue 12, then through a cross-over flue 24 and down through a flue [4 across the opposite wall of oven l8. During this half of the heating cycle the flue I2 is termed the "on flue, and the flue I4 is termed the off flue. During the second half of the heating cycle gas in introduced into the bottom of the former off flue H. The products of combustion pass upwardly through the flue l4 then through the cross-over flue 24 and down through the former on flue l2. In the second half of the cycle the flue [4 becomes the on flue and the flue l2 the off flue. Therefore the on flue is that flue in which the gas is being burned and the off flue is the flue through which products of combustion from an on flue are passedfor heating an oven wall. The products of combustion or waste gases, pass from the bottom of the off flues through the corresponding regenerator to heat the regenerator so that air which is introduced for burning the gas may be preheated by passing through the regenerator. The regenerators therefore may be oil. and on in the cycle depending on whether they are being heated by exhaust waste gases or whether they are used in preheating air for combustion.

The gas burners for heating the flues are mounted in the refractory setting below the coke oven flues as illustrated in Figures 1 and 2. The gas burners are made up of mixing tubes 26 which extend from the bottom of the flues down to the bottom of the regenerators. At the bottom of the mixing tube is a Venturi throat 28 which forms part of an aspirating mixer. Immediately below the Venturi throat 28 is an inspirating nozzle 30 which is arranged to direct gas supplied by a supply pipe 32 directly into the central portion of the Venturi throat 28. At the side of the Venturi throat is a waste gas inlet tube 34 by which waste gases are drawn into'the mixing tube 28, by the action of the inspirating nozzle in the Venturi throat. The area beneath the Venturi throat 28 and surrounding the nozzle 30 is in effect an inlet chamber to which the inlet passage 34 connects. The parts 26, 28, 30 and 34 constitute the gas burner and mixer apparatus.

When a flue is operating in oil condition, waste gases pass from the bottom of the flue, for example, flue [4 down through a mixing tube 26 through a waste gas tube 34, then to a connecting tube 38 to the waste gas tube 34 of a gas burner supplying gas to the flue l2. The off and on burners are arranged in pairs along the longitudinal axis of an oven as shown in Figures 1 and 2. One burner operates as an on burner while the other burner is an off burner, the products of combustion passing into and through the corresponding on and off flue. The burners supply rich gas to the heating flues and it is customary to mix waste gas with the rich gas in the mixer tubes 26 to adjust B. t. u. value of the gas to produce a long flame combustion in the flues for effectively heating the flues. The rich gas ordinarily has a heating value of 550 to 600 B. t. u.s per cubic foot and sufllcient waste gas is mixed with the rich gas to produce a mixture of about 250 to 300 B. t. u.s per cubic foot. Such a. mixture will not crack in the heated mixing tube 26 that is a part of the heated refractory wall of the regenerator.

When coke oven or rich gas is used solely for heating the flues l2 or H, preheated air is introduced into the bottom of the heating flue adjacent the top of the mixing tube 26. If flue I2 is the on flue, then air for combustion passes up through the regenerators l6 and IE to preheat the air. If I 4 is the on flue, then preheated air will pass upwardly through the regenerator 28 and the left half of the regenerator 22 to introduce the gas-waste gas mixture at the top of the mixer tube 26.

If blast furnace gas is being used for heating the flues the blast furnace gas is preheated by passing through a regenerator. As illustrated in Figure 1, blast furnace gas will pass up through the regenerator 22 to be preheated and will flow therefrom through the left hand passage at the top of the regenerator to the flue I4 where the blast furnace gas will meet with rich gas which is introduced into the bottom of the flue I 4 through a burner tube 26. The air for burning the blast furnace gas is introduced through the regenerator 20. During this part of the cycle the regenerator l6 and regenerator l8 are heated by gases passingdownwardly through the flue I2. On the otherhalf of the cycle blast furnace gas is preheated in regenerator l6, burned in flue l2, then passes across and down through flue I4 and out through regenerators 20 and 22. At the same time a rich gas-waste gas mixture passes up through the burner tube 26 to assist in burning the blast furnace gas.

The construction and arrangement of the burners in the oven structure constitutes an important feature of the present invention. The burner parts, such as the mixer tube 28, the Venturi throat 28, the inlet chamber beneath the Venturi throat, and the gas inlet passage 34 are formed in and constitute parts of refractory shapes that are used in building up the regenerator walls of the furnace structure. These refractory shapes which make up the burner parts arev held together with a cement which will cause all of the burner parts to move as a unit under the expansion and contraction movement of the regenerator wall structure. The refractory structure is mounted upon a fixed concrete mat 38. The regenerator walls and burner shapes are movably mounted on the mat 38 to permit movement of the shapes under various conditions of expansion and contraction. As shown in Figure 3, the refractory shapes surrounding the connecting tube 36 are provided with expansion joints 40 to permit expansion of the shapes longitudinally of the tubes 36 or transversely of the coke oven. Other expansion joints are provided to permit movement of the burner shapes and regenerator walls longitudinally of the coke oven. By having the burner parts formed as part of the refractory shapes the expansion and contraction of the shapes will not deform the burner parts 26, 28 or 34. To cause the inspirating nozzle 30 to direct gas into the central portion of the Venturi throat 28 the nozzle is rigidly secured to a metal block or anchor member 42 which is mounted with cement 43 in the refractory shape 44 that forms the base of the aspirating mixer. Therefore when the shape 44 moves transversely or longitudinally of the oven the nozzle 30 will move with the shape and maintain its accurately centered position below the Venturi throat. The metal block 42 is not attached to the upper surface of the mat 38 but may move along the surface of the mat under expansion and contraction of the refractory material surrounding and enclosing the block. The nozzle 30 is secured to the metal block 42 by screw-threads and may be inserted and removed through the supply pipe 32. By this means different sizes of nozzles may be inserted into the burner to obtain any desired supply of gas to the burner. It will be understood that the nozzle used for supplying rich gas when the ovens are being heated with oven gas will be larger and of a different type than the nozzle which is used when the burners are supplying a small amount of gas for enriching blast furnace gas. Supply pipe 32 will move with the metal block or anchor member 42 under expansion and contraction of the refractory shape 44 and therefore an enlarged opening 46 is provided in the mat 38 to permit the pipe to move with the metal block 42. The lower end of the supply pipe 32 is connected by means of a flexible tubing 48 with a gas supply main 50, this flexible tubing permitting the movement of the pipe 32 under expansion and contraction of the refractory burner parts.

The principal expansion of the oven structure and walls takes place when the oven is heated from a cold condition to a hot operating condition. Some expansion or contraction also takes place when the operating temperature is materially changed for coking different types of coal. The main expansion and contraction of the refractory structure takes place longitudinally of the coke oven from the center outwardly to both ends of the oven. There is also expansion and contraction movement of the oven structure transversely of the coke oven, this expansion being from the center of an oven battery in opposite directions to both ends of the battery.

The connecting tube 36 for conducting the waste gases that are recirculated through the burners is loosely mounted in the refractory shapes to provide for the expansion and contraction of the furnace structure. The tube 36 is made up of a metallic tubular outer shell 52 with a refractory lining 54, the refractory preferably being a clay refractory. The refractory shapes which surround the tube 36 makes a close, but

sliding, lit with the tube, whereby the refractory shapes may move independently of the tube and thus permit the tube to expand and contract independently of the expansion and contraction of the shapes surrounding it. Asbestos gaskets 56 at each end of the tube 36 are used for packing in the expansion joints to close the gap between the outside of the tube and the circular opening in the shapes so that the waste gases will be caused to flow to the center through the opening in the tube.

As illustrated in Figure 2 the gas burners are formed in pairs at opposite sides of an oven. The waste gas tubes 34 of each pair of burners are connected together and one cross connecting tube 36 is arranged between the burners to supply waste gases simultaneously to each of the pair of burners.

The preferred form of the invention having been thus described, what is claimed as new is:

1. In a structure of the class described, in combination, a supporting mat, refractory shapes mounted on and supported by said mat to form a plurality of regenerators with parallel dividing walls and above which are located coking chambers which are parallel with the regenerator division walls, each of said coking chambers being intermediate a pair of vertically flued heating walls with the flues in said walls communicably interconnected at their upper parts into a first and a second set for operation in alternation, said refractory shapes having inlet chambers formed therein above said supporting mat, each of said inlet chambers being connected to the lower part of a vertical flue by a burner tube formed in said refractory shapes and having a Venturi throat adjacent its lower end, each inlet chamber being connected through a connecting conduit formed in said refractory shapes with the inlet chamber associated with a flue in a different set, each of said inlet chambers having located thereunder a metal plate supported on said supporting mat and incorporated in said refractor shapes so as to be movable therewith, each of said plates having a fuel gas supply pipe secured thereto and extending downwardly through an opening in said supporting mat, each of the openings in said supporting mat being substantially larger in size than the associated supply pipe to thereby permit unrestrained move ment of said pipe relative to said mat, and a nozzle associated with each inlet chamber and disposed to direct fuel gas supplied through the associated supply pipe directly into the central part of the Venturi throat of the associated burner tube, each of said nozzles being supported from and movable with the metal plate located beneath the associated inlet chamber, whereby on expansion and movement of said refractory shapes each of said nozzles is maintained in substantially the correct relationship to the Venturi throat of the associated burner tube.

2. In a structure of the class described, in combination, a supporting mat, refractoryv shapes mounted on and supported by said mat to form a plurality of regenerators with parallel dividing walls and above which are located coking chambers which are parallel with the regenerator division walls, each of said coking chambers being intermediate a pair of vertically flued heating walls with the flues in said walls communicably interconnected at their upper parts into -a first and a second set for operation in alternation, said refractory shapes having inlet chambers formed therein above said supporting mat, each of said inlet chambers being connected to the lower part of a vertical flue by a burner tube formed in said refractory shapes and having a Venturi throat adjacent its lower end, each inlet chamber being connectedthrough a. connecting conduit formed in said refractory shapes with the inlet chamber associated with a flue in a different set, a metallic anchor member located beneath each of said inlet chambers, each of said anchor members having a fuel gas supply pipe secured thereto and extending downwardly through an opening in said supporting mat of substantially larger size than said pipe, each of said anchor members having rigidly and detachably secured thereto an upwardly extending gas nozzle disposed substantially co-axially of the Venturi throat of the associated burner tube and adapted to direct into the central part of said Venturi throat fuel gas supplied through the associated supply pipe,each of said anchor members being rigidly incorporated in said refractory shapes so as to be movable with said refractory shapes on expansion thereof, whereby on expansion and movement of said refractory shapes each of said nozzles is maintained in substantially the correct relationship to the Venturi throat of the associated burner tube.

3. In a horizontal coke oven of the underjet t pe, in combination, a supporting mat, refractory shapes mounted on and supported by said mat to form a first and a second substantially vertical wall which are spaced apart a short distance, said refractory shapes having formed therein a first inlet chamber beneath said first wall and a second inlet chamber beneath said second wall, each of said walls having a burner tube formed therein and leading upwardly from the associated inlet chamber, each of said burner tubes having a Venturi throat adjacent its lower end, said refractory shapes having a passage formed therein and connecting said first and second inlet chambers, a metal tube of somewhat smaller diameter than said passage loosely mounted in said passage, a yieldable packing element adjacent each end of said tube and positioned between said tube and said passageway to permit movement of the tube in said passageway, a fuel gas supply pipe chamber and disposed substantially co-axially of the Venturi throat of the associated burner tube to direct fuel gas supplied through the associated supply pipe directly into the central part of the Venturi throat of the associated burner tube, each of said nozzles and the associated supply pipe being rigidly mounted with respect to said refractory shapes and being movable with respect to said supporting mat, whereby on expansion and movement of said refractory shapes each of said nozzles is maintained substantially co-axially of the Venturi throat of the associated burner tube.

JOSEPH vm ACKEREN.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Great Britain Oct. 29, 1937

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