US3732070A

US3732070A - Burner

Info

Publication number: US3732070A
Application number: US00129868A
Authority: US
Inventors: J Vietorisz
Original assignee: Koppers Co Inc
Current assignee: Raymond Kaiser Engineers Inc
Priority date: 1971-03-31
Filing date: 1971-03-31
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08

Abstract

A burner used in conjunction with heat exchangers or furnaces has a chamber that is divided into a gas-mixing zone and a combustion zone, a means for axially introducing selected amounts of a relatively slow-flowing combustion supporting first gas into the mixing zone, a means for radially introducing selected amounts of a relatively rapid-flowing combustion supporting second gas as a plurality of gas streams into the gas mixing zone whereupon the first and second gases become intimately admixed, and a means in the combustion zone for igniting the admixed gases to generate hot exhaust gases for supplying heat to be stored in the heat exchanger or utilized otherwise.

Description

United States latent 1 vietorisz 1 May 8,1973

[ BURNER [75] Inventor: Joseph A. Vietorisz, Pittsburgh, Pa. [7 3] Assignee: Koppers Company, Inc., Pittsburgh,

[22] Filed: Mar. 31, 1971 [21] Appl. No.: 129,868

[52] U.S. Cl. ..263/19 R, 431/352 [51] Int. Cl ..F23l 9/00 [58] Field of Search ..263/19; 431/2, 4,

[56] References Cited UNITED STATES PATENTS 3,227,202 1/1966 Morgan ..239/431 X 3,574,508 4/1971 Rothhaar 3,244,220 4/1966 Kloecker ..431/5 X 3,597,141 8/1971 Fracke et al ..431/353 3,267,927 8/1966 Hirschberg ..239/431 X 5 gen Kinnisom ..431/2 Krapf ..263/19 Primary Examiner-Edward G. Favors Attorney-Fred C. Trenor, Oscar B. Brumback and Olin E. Williams A burner used in conjunction with heat exchangers or ABSTRACT furnaces has a chamber that is divided into a gas-mixing zone and a combustion zone, a means for axially introducing selected amounts of a relatively slow-flowing combustion supporting first gas into the mixing 17 Claims, 6 Drawing Figures a 4 /5 0 25 27 z: 3/ 2 5 l9 j 2/ Pmmmm 3,732,070

SHEET 2 BF 2 -J0.5E PH ,4. VIE Toe/5a I H15 AGE/LIT luveuroe.

FQED C REMbE H' I BURNER BACKGROUND OF THE INVENTION 1 Field of the Invention The invention relates to a heat exchanger for use in conjunction with a metallurgical furnace, and more particularly, to an improved gas burner disposed on the top of a blast furnace stove forbuming combustible gases to produce hot exhaust gases that heat the refractory bodies in the stove.

Heretofore, blast furnace stoves have been comprised of four major compartments; the first being a vertical heat-storing chamber (referred to as the checkerwork chamber) containing a checkerwork arrangement of heat-absorbing refractory bodies; the second being an adjacent vertical combustion chamber (referred to as the combustion chamber) in which fuel gas or the like is burned to generate hot gases for heating the refractory bodies in the checkerwork chamber; and the third being a dome-shaped chamber (referred to as the dome) at the top of both the checkerwork and combustion chambers, and the fourth being a plenum chamber below the checkerwork chamber in which the combustion products are collected or the cold blasts of air are distributed. A partition wall divides the combustion chamber from the checkerwork chamber.

In operation of the above-described blast furnace stove mixtures of fuel gas and air are admitted into, ignited and burned within the combustion chamber to generate hot, exhaust gases. The hot, exhaust gases, generated in the combustion chamber, flow upwardly through the combustion chamber, through the dome, and flow downwardly through the checkerwork chamber to heat the refractory bodies therein. After enough heat has been stored in the refractory bodies, the gas burning is stopped, and cold blasts of air, admitted at the bottom of the checkerwork chamber,

ascend upwardly through the checkerwork chamber,

and the air is gradually heated to a selected hot blast temperature; in newer furnaces the temperature is about 2000F. The heated air passes through the dome and descends downwardly through the combustion chamber to the hot blast main and thence to the blast furnace.

Blast furnace operators have proved the theory that higher blast air temperature increases the production rate of a blast furnace. Accordingly, the temperatures in the blast furnace stoves have been increased; however, the above-described conventional blast furnace stove is not best suited to operate at prolonged temperatures in excess of 2000F. as several serious problems may occur. For example, the partition wall may become over-stressed by higher operating temperatures in excess of 2000F., and, consequently, cracks develop in the partition wall whereby cold blasts of air by-pass the heated refractory bodies in the checkerwork chamber. Also, the refractory bodies near the dome are heated to higher temperatures than the refractory bodies more remote from the dome. Consequently, the refractory bodies near the dome require a greater refractoriness than those refractory bodies remote from the dome. conventionally, the checkerbricks having a high alumina content are used in the top layers of the blast furnace stove; the percentage of alumina is higher for increased blast temperatures. The cost of using bricks having a very high percentage of alumina is prohibitive of their use. However, only bricks having the high percentage of alumina can raise the softening point of such bricks over and beyond the temperatures to which they are exposed when the stove is to provide hot blast line temperatures well in excess of 2000F. Recently, silica bricks have been experimentally used near the dome because of their higher refractoriness. The temperatures in such blast furnace stoves must be maintained during their full service life at temperatures above the temperature at which silica bricks undergo detrimental crystallographic changes in order to maintain the integrity of the silica bricks.

2. Description of the Prior Art Several solutions to the foregoing problems have been attempted. One solution has been to isolate both the combustion chamber from the checkerwork chamber in separate shells and to connect them together with a flue that has properly designed expansion joints. This solution has been too expensive because the exterior combustion chamber requires an additional long stack, lined with an insulating refractory for adequate insulation to minimize the heat losses, and because of the specially designed expansion joints that can adjust to the differences in the thermal expansion of the two connected chambers during the operation of the stove. Another solution has been to modify the combustion chamber and to provide merely a checkerwork chamber and to modify the dome at the top thereof by providing a burner around or above the dome in which fuel gas and air are burned to generate hot, exhaust gases for heating the refractory bodies in the checkerwork chamber, often called top firing".

Various burner arrangements have been proposed for the top firing of blast furnace stoves. For example, in U. S. Pat. No. 3,473,793, air and fuel gas are admixed in an annular chamber around the modified dome of the stove wherefrom the mixed gases move upwardly through a number of slits into the dome. The mixed gases are burned in the dome to produce hot, exhaust gases. The hot, exhaust gases then travel downwardly from the dome into the checkerwork chamber. The burning gases flow generally upwardly and the burnt gases flow generally downwardly. The counter flow of burning and burnt gases may result in unstable and incomplete combustion. In U. S. Pat. No. 3,380,723, air and fuel gas are admixed in a frustoconical chamber situated on top of the blast furnace stove. The air is introduced axially into the chamber and the fuel gas is introduced tangentially into the chamber through a single port whereby these gases are admixed and are burned in the chamber to produce hot, exhaust gases. The flame of the burning mixed gases undergo an indistinct, conical, swirling movement that will save the lining from scouring, however, the gases will tend to leave the center of the combustion chamber; consequently, the combustion of the mixed gases is nonuniform throughout the cross-section of the frusto-conical chamber. Ultimately, the refractory bodies in the checkerwork chamber may not be heated uniformly by the hot exhaust gases and the uniform and efficient heating of cold blasts of air may be decreased. In both patents the refractory linings of the burners do not merge smoothly with or share a common tangent with the refractory linings of the stove. Above the stove at the inner surface of the conical dome the flow of the burning and burnt gases will be particularly turbulent resulting in gas temperatures and pressures that are not well-balanced unless the included angle of the cone is quite small i.e., unless the cone is exceedingly long.

The present invention relates to an improved burner design that provides more stable combustion and wellequalized temperatures and pressures in the burner. The burner of the present invention is made from refractory bodies and, hence, water-cooling the various members of the burner is unnecessary. An intimate mixture of the air and fuel gas is achieved in mybumer and the distances the flame travels are greatly reduced whereby a more uniform burning of the mixed gases occurs. Smooth expansion and flow of burnt gases are secured by using specially shaped combustion zone contours. The introduction of all the combustion supporting gases is symmetrical about the central axis of the burner; consequently, localized hot spots in the dome are eliminated.

SUMMARY OF THE INVENTION In accordance with the invention a burner for use with heat exchangers or furnaces comprises a burner chamber that, when disposed at the top of the stove, is symmetrically arranged about the central vertical axis of the stove, a first conduit communicating with the top of the burner chamber for carrying a combustion-supporting first gas and for axially introducing the first gas at relatively low velocities into the burner chamber, a header surrounding a portion of the burner chamber for receiving a combustion-supporting second gas, a second conduit communicating with the header for carrying the second gases and for introducing the second gases into the header, a burner ring between the burner chamber and the header having a plurality of generally radially extending conduits through the ring for radially introducing a plurality of streams of the second gas at relatively high velocities into the burner chamber, whereby the first and second gases become intimately admixed in the burner chamber, means in the burner chamber for igniting the first and second gases whereby the admixed gases are burned to produce hot, exhaust gases for heating the refractory checkers in the blast furnace stove.

GENERAL DESCRIPTION OF THE DRAWINGS In the drawings: FIG. 1 is a vertical sectional view of the dome portion of a blast furnace stove illustrating an embodiment of the burner of the invention;

FIG. 2 is a top view ofa segment of the burner ring of FIG. 1;

FIG. 3 is a cross-sectional view of the burner ring segment of FIG. 2 taken at line III-III;

FIG. 4 is a top isolated view of the burner ring of FIG. 1;

FIG. 5 is a top isolated view of another embodiment of the burner ring of FIG. 4; and

FIG. 6 is an isometric view of a segment of the burner ring of FIG. 1.

DETAILED DESCRIPTION In FIG. 1 the top portion of a blast furnace stove 11 includes a checkerwork chamber 13, a dome 15 at the top of the chamber 13 and an embodiment of the improved burner 17 in accordance with the invention.

Chamber 13 has a metal shell 19 that has an internal refractory and insulating lining 21 and chamber 13 contains a quantity of conventional heat-absorbing refractory bodies or bricks 23, referred to as checkerwork". The refractory bodies 23 are capable of being heated and of storing heat and, therefore, of imparting such stored heat to a blast of cold air which is introduced into the blast furnace stove in a conventional manner.

The dome 15, at the top of chamber 13, has a metal shell 25 and an internal refractory and insulating lining 27 that defines a chamber 28. Dome 15 preferably has hemispherical shape or configuration. The dome 15 is supported by brackets 31 that are fixed to shell 19 so that the dome is independent of the radial thermal movements of shell 19. As shown in FIG. 1 the refractory lining 27 of dome 15 is laterally adjacent to and overlaps refractory lining 21 of chamber 13. This arrangement is desirable since it permits a free axial thermal movement of the refractory bricks 23 and refractory lining 21 up into dome 15, without exerting thermal forces on the domes refractory lining 27.

A conventional nozzle 29 having a metal shell 35 and an internal refractory and insulating lining 37 extends from a side of the dome 15, as shown in FIG. 1. This nozzle 29 conveys the hot blast of air, heated in chamber 13, through conventional valve 39 and conduit 41 to a conventional hot blast main (not shown).

In accordance with the invention, burner 17, as illustrated in FIG. 1, is situated on top of dome 15 and has a metal shell 43 and an internal refractory and insulating lining 45 that defines a chamber 47 for mixing and burning air and fuel gas. Chamber 47 is divided into an upper gas-mixing zone A inwhich the combustible gases are intimately admixed, and a lower combustion zone B in which the mixed gases are burned. The burner includes a first aperture 49 at its top for axially receiving combustion supporting first gas (preferably an enriched premixture of fuel gas and air) into chamber 47, a second aperture 51 at its side for radially receiving a combustion supporting second gas (preferably air), an annular channel or header 53 communicating with the second aperture 51, and, a burner ring 55 communicating with the annular channel 53 and the gas-mixing zone A of chamber 47.

Burner chamber 47 may have any cross-sectional configuration that increases downwardly in the direction of gas flow as shown in FIG. 1; however, the internal surface of the refractory lining 45 of burner 17 has generally a curved contour 64 that merges smoothly with the refractory lining 27 of dome 15 so that the refractory linings 45 and 47 share a common tangent whereby a smooth flow of gases from the burner to the dome is achieved.

The curved contoured downwardly increasing crosssectional configuration of chamber 47 is an advantageous feature of the invention. As the gases are burned therein the volume of the gaseous products of combustion increase and the downwardly increasing cross-sectional configuration of the chamber allows ex- The annular channel 53 receives the second combustible supporting gas and uniformly distributes it around the burner ring 55.

The burner ring 55 is composed of a refractory material and, as illustrated in FIGS. 1 and 2, includes a plurality of conduits or ports 57 that extend entirely through the ring, and that communicate with the gasmixing zone A of burner chamber 47. The conduits 57 are superimposed one above the other in a vertical direction, being parallel to each other as illustrated in FIG. 1. If desired, however, the conduits 57 need not be arranged in a parallel fashion in the vertical direction. Conduits in two elevations are shown in FIG. 1; however, more conduits in more than two elevations ma be used as desired.

In FIG. 3 the conduits 57 are downwardly inclined at an angle (a) in respect of line dd drawn perpendicularly to the vertical central axis CC of chamber 47. This angle may vary, and the conduits 57 may be inclined either upwardly or downwardly at angles from 0 to 45 with respect to line d-d. The angle (a) is selected to suit the fuel characteristics and heating requirements of the burner.

The conduits 57 in the drawings are radially arranged with respect to the burner ring 55 and to each other so that the centerlines of the conduits converge at a common axis 0 in FIG. 2 and that is the centerline of the burner in FIG. 4 so that the gases issuing from each conduit travel the same distance to reach the common axis. When all the centerlines of each conduit are so arranged, the velocity of the gas streams issuing from the respective conduits 57 will be the same at the common axis because all of the gas streams travel the same distance to reach the axis. Equal gas velocities at the common axis is a desirable feature of the invention as it encourages a more uniform combustion of the mixed gases in chamber 47. If desired, however, the conduits may be eccentrically arranged with respect to the burner ring and to each other so that the centerlines of each conduit are tangent to a circle of eccentricity, and again, the gases issuing from each conduit travel the same distance to the circle of eccentricity.

The burner ring 55, as shown in FIG. 3, has a top surface 59, a bottom surface 61, an inside surface 63 and an outside surface 65. The top and

bottom surfaces

59 and 61 are planar and, as shown herein, are parallel to each other so that the burner ring may easily be installed into the cutaway section 54 of the burner 17. The inside surface 63 as shown in FIG. 3, is a frustoconical surface and the elements of this surface are also coextensive with the elements of the internal surface of the refractory lining 45, thereby providing a smooth, unbroken flow of gases through the burner 17 as shown in FIG. 1. The inside surface 63 diverges with respect to the central axis CC so that the cross-section of the burner ring 55 increases downwardly in the direction of gas flow for the purposes previously described. The burner ring 55 is so constructed that it may be independently removed and installed in the burner 17. For this purpose, a manhole 67 is provided in the side of burner 17 so that the burner ring 55 is accessible from the outside of the blast furnace dome 15, as shown in FIG. 1. More than one such manhole may be provided if desired.

The burner ring 55, illustrated in FIGS. 4 and 5, is made of four segments (69, 71, 73 and 75) and each segment as shown comprises a quarter section of the ring 55. The ring 55, however, may be comprised of other than four sections, if desired, and may have other configurations such as an oblong or an oval shape or the like. In FIG. 4 the ring segments 69-75 are all equidistant from the central axis (C-C) of the chamber 47 so that the inside surface 63 of each ring segment is equidistant from the central axis (CC) of the burner 17. In this position the conduits are radially arranged so that their centerlines converge at the central axis of the chamber 47.

In FIG. 5 the embodiment of the burner ring is shown where each segment (69-75) is eccentrically arranged with respect to the central axis (CC) of the chamber 47 and the inside surfaces 63 of the adjacent ring segments are not equidistant from the central axis (CC In this position the centerlines of each conduit 57 of each segment converge at a common axes (a, b, c, d) but each common axis is equally eccentric to the central axis (CC) of the chamber 47. The gas streams issuing from the conduits 57 into chamber 47 converge at a location eccentric to the central axis of the chamber and thereby they effect a swirling action of the gases, as shown in FIG. 5.

FIG. 1 shows a conventional pilot burner 77 that is directed toward the combustion zone B of the chamber 47 for igniting the gases which have been admixed in the gas-mixing zone A. An ignition port 79 is provided in the side of the burner 17 for lighting the pilot burner 77.

The combustion supporting first gas is conveyed through a conventional feed conduit 95, through a conventional stop valve 97 and through a conventional flow regulating device 99 into an increaser 101. Increaser 101 has a metal shell 103 and an internal refractory lining 105. The increaser 101 is generally frustoconical with the smaller end connected to the flow regulating device 99 and with the larger diameter connected to a mixer conduit 89, described hereinafter. The increaser 101 prevents any backfiring from occurring within the flow regulating device 99. Consequently, the flow regulator 99 and the stop valve 97 need not be water cooled as the combustion of the first gas can not occur in the increaser 101 nor are they exposed to intense heat radiation. The increaser may have a nozzle 113 in its side, if desired, for the admission of an enriching gas having a higher heating value than the first gas. Such enriching gases may include coke oven gas, natural gas, and the like. The enriching gas boosts the flame temperature of the burning mixture of gases occurring in the burner 17 and increases the heat input into the checkerwork chamber.

Increaser 101 engages the mixer conduit 89, as shown in FIG. 1, which is an optional feature of the invention. The mixer conduit has a metal shell 91 and an internal refractory lining 93 that has the same inner diameter as the adjacent refractory lining 105 of the increaser. Thus, there is a smooth flow of the first gases from the increaser through the mixer conduit. Companion flanges 107 and 109 of the increaser and mixer conduit engage each other and are secured together with fasteners (not shown) such as bolts. The mixer conduit 89 axially receives the first gases from the increaser 101 and tangentially receives a portion of the second gases (preferably air called primary air) from conduit 1 1 1, as shown in FIG. 1. The first gases and the portion of the second gases are intimately premixed in the mixer conduit 89 to provide a gas premixture since the portion of second gases enter the mixer tangentially to effect a swirling movement of the gases. This premixing is a desirable feature of the invention in that it effectively speeds up the combustion that subsequently occurs in burner 17.

An elbow 80 is situated on top of burner 17, engaging mixer conduit 89 and communicating with the first aperture 49 of the burner 17 as shown in FIG. 1. The elbow 80 having a metal shell 81 and an internal refractory lining 83 has a flange 85 at one end that engages flange 62 of burner 17. The elbow 80 also has a flange 82 at its other end that engages flange 108 of the mixer conduit 89 so that elbow 80 is removable from the burner whereupon workman may enter the burner for repairwork and the like. Fasteners (not shown) such as bolts are used to secure the elbow to the burner and the mixer conduit.

During the operation of the burner 17 the refractory lining 83 will absorb some radiated heat from the combustion of the mixed gases and, consequently, the heat in the refractory lining 83 will tend to preheat the premixed gases flowing through the elbow which will desirably result in slightly higher flame temperatures in the burner when the final mixture of gases is burned. A desirable feature of the elbow 80 is that its refractory lining 83 merges smoothly with refractory lining 93 of the mixer conduit 89 at one end and with refractory lining 45 of burner 17 at the other end so the gases pass therethrough smoothly.

The second combustion supporting gas, usually air, is conveyed through a feed conduit 115 toward burner 17, as shown in FIG. 1. At a tee-section 117 in the feed conduit 1 15, the air may be split into primary air and secondary air in the preferred embodiment of the invention by channelling the primary air into conduit Ill and the secondary air into a conduit 119. The primary air" in the conduit lll passes through stop valve 121 and a regulating device 123, and the secondary air" passes through stop valve 125 and a regulating device 127, as shown in FIG. 1. The regulating device 123 keeps the flow of "primary air through conduit 111 at a level such that the premixture of primary air and fuel gas in mixer conduit 89 is below the flammable range. Stop valve 121 can shut off the supply of primary air" altogether if desired.

The secondary air passes through conduit 1 19, increaser 129, nozzle 131 and thence in to annular channel 53, as shown in FIG. 1 whereupon the secondary air is uniformly distributed around burner ring 55 as previously described. The increaser 129 has an increasing diameter in the direction of gas flow so as to prevent backfiring of gases in the burner 17 from occurring in flow regulating device 127. Both the increaser 129 and the nozzle 131 have a metal shell 133 and an internal refractory lining 135.

In the operation of the preferred embodiment of the burner of the invention, blast furnace gas is admitted into conduit by valve 97, natural gas is admitted through nozzle 113 into increaser 101 and air is admitted into conduit whereupon a portion of the air (primary air) passes through conduit 11] into mixer conduit 89. The primary air tangentially enters mixer conduit 89 and becomes admixed with the blast furnace gas and the natural gas and causes the premixed gas to undergo a swirling direction in FIG. 1 in a clockwise direction as viewed from the increaser 101 to the burner 17. The other portion of the air (secondary air) passes through increaser 129, nozzle 131 into header 53 and eventually into the gas-mixing zone (A) of the burner as a plurality of streams at relatively high velocities. In one embodiment of the invention the streams of secondary air enter the gas-mixing zone radially; in another embodiment the streams enter the gas-mixing zone eccentrically of its central axis CC so that the gases will whirl about the axis as shown in FIG. 5 in a counter-clockwise direction. By disposing the conduits or segments in the opposite direction, a clockwise whirling action of the gases may be achieved. Very intimate admixing will be obtained in any case by shearing and entrainment of the radially flowing secondary air at high velocities in the premixed gases which flow swirling downwardly at relative low axial velocities. The premixed gases entering the chamber axially may swirl in an opposite direction of the secondary air radially entering the chamber so that a good homogeneous admixture of the gases is achieved in the gas-mixing zone.

The novel mixing action above described results in a short flame length in the burner, and in the rapid combustion of the mixed gases so that no flame propagates into the top bricks in the checkerwork chamber. Advantageously, complete combustion occurs in a relatively short time in the gas burning chamber even when non-enriched blast furnace gas is being used (which is known to have a low rate of flame propagation). Of course, the respective flow rates of the blast furnace gas and of the secondary air into the gas mixing zone A of chamber 47 may be regulated to provide the desired heat release. It is postulated that the axial flow velocity of blast furnace gas be less than the radial, or near radial flow velocity of secondary air into the gas mixing zone of chamber 47 as this provides the thorough admixing and short flame lengths and permits sufficient time for complete combustion entirely within the burner and the dome.

A substantial part of the heat generated by the combustion of the mixed gases is absorbed by the refractory bodies in the checkerwork chamber 13 and the burner is operated until the refractory bodies have absorbed enough heat to preheat a cold blast of air to the required temperature for a preset period of time for use in the blast furnace.

After the refractory bodies in the checkerwork chamber 13 have been sufficiently heated, valves 97,

121 and 125 are closed to terminate the burning of gases in the burner. Subsequently, cold blasts of air are admitted into the bottom of the checkerwork chamber 13 (not shown) which pass upwardly through the checkerwork chamber gradually being heated to the required temperatures, then, exit the checkerwork chamber through nozzle 29, valve 39 and conduit 41 to enter blast furnace via the hot blast main (not shown).

A feature of the invention is that fuel gas and air may be used interchangeably. As contemplated in the drawings fuel gas is axially introduced and air is radially introduced into the burner, however, the burner of the invention is so constructed that air may be axially introduced and fuel gas radially introduced into the burner,

An optional feature of the invention is illustrated in FIGS. 3 and 6. An embodiment of a control device or shutter 137 is shown for closing or shutting off or opening some of the conduits 57 to adjust the flow velocities of the secondary air through the conduits 57 into the gas-mixing zone A of burner chamber 47. to accommodate widely varying burning rates. The shutter 137 in its embodiment described herein comprises a frustoconical plate 139 that extends around burner ring 55 as shown in FIG. 6. The plate 139 fits in a cutaway section 149 of the outside surface 65 of the burner ring 55 and is movable along the circumference thereof. The plate 139 has a plurality of apertures 143 that have an inverted -L shape as shown in FIG. 6. The plate 139 is to be moved manually; however, it could be moved automatically, if desired. The plate. 139 in FIG. 6 is in a position in which all of the conduits 57 are open. By moving plate 139 to the right a specified distance all of the upper conduits will be closed while the lower conduits will remain open. A desirable feature of the shutter 137 is that the shutter is situated on the outside surface 65 of the burner ring where it is not exposed to direct thermal radiation but is protected by the refractory ring 55 and is accessible for adjustment from manholes 67.

It will be recognized that the shutter 137 may be greatly modified to provide different arrangements for shutting off the conduits 57. For example, apertures other than L-shaped apertures, may be used, or the shutter may be moved axially rather than circumferentially to shut off or to open the conduits. The important feature of any modified embodiment of shutter 137 is that a number of conduits, preferably symmetrically located, may be rendered inactive for reduced secondary air supply to obtain desired flow velocities of secondary air into the gas-mixing zone A of burner chamber 47 and that the shutter 137 is protected from thermal radiation. Strategically located observation ports and thermo wells may be provided for effective control (not shown).

Although the present invention has been illustrated with a single embodiment, it will be understood that it is illustrative of the invention and by no means restrictive thereof. Those skilled in the art will readily recognize that the invention can be applied not only on the top of a heat exchanger but in any position in conjunction with any furnace. Therefore, numerous modifications can be made within the scope of the invention without deviating from the spirit of the following claims or without sacrificing their advantages.

What is claimed is:

1. A burner for a top-fired blast fumace stove that has a checker chamber and a dome at the top thereof comprising:

a. a burner chamber that is disposed at the top of said dome and that is symmetrically arranged about the central vertical axis of said dome;

a first conduit communicating with the top of said burner chamber for carrying a combustion-supporting first gas and for axially introducing said first gas at relatively low flow velocities into said burner chamber;

c. a header completely surrounding a portion of said burner chamber for receiving a combustion-supporting second gas;

a burner ring between said burner chamber and said header having a plurality of generally radially extending conduits through said ring for radially introducing at relatively high flow velocities a plurality of streams of said second gas inwardly into said burner chamber;

e. a second conduit communicating with said header for carrying said second gases and for introducing said second gases into said header;

f. means in said burner chamber for igniting the first and second gases whereby the first and second gases become intimately admixed in said burner chamber and said admixed gases are burned to produce hot, exhaust gases.

2. The burner of claim 1 including an increaser in operative association with said first conduit for preventing the backfiring of any gases into said first conduit; said increaser having an increasing size in the direction of gas flow therethrough.

3. The burner of claim 1 wherein said first gas is a fuel gas and said second gas is air.

4. The burner of claim 3 including a nozzle in said increaser for introducing an enriching gas into said increaser for admixture with said fuel gas passing therethrough; said enriching gas having a heating value greater than said fuel gas.

5. The burner of claim 1 including a mixer conduit in operative association with said first conduit; said mixer conduit having a means for tangentially receiving a portion of said second gases whereby said first gases passing axially through said mixer conduit are intimately admixed with said second gases tangentially entering said mixer conduit.

6. The burner of claim 1 including an increaser in operative association with said second conduit for preventing the backfiring of any gases into said second conduit; said increaser having an increasing size in the direction of gas flow therethrough.

7. The burner of claim 5 including a means in operative association with said second conduit for diverting a portion of said second gases to said mixer conduit and for diverting the other portion of said second gases to said header.

8. The burner of claim 1 including manholes in said burner chamber for exterior access to said burner ring.

9. A burner for use in conjunction with high temperature heat exchangers or furnaces comprising:

a. a chamber having i. a gas-mixing zone, and ii. a combustion zone;

b. means for introducing a combustion supporting first gas generally axially of said chamber into said mixing zone at relatively low flow velocities;

c. said gas mixing zone including i. a burner ring that is comprised of a plurality of refractory segments; said ring segments having a plurality of generally radially arranged conduits that are inclined at an angle with respect to the central axis of said chamber for introducing a combustion-supporting second gas generally radially of said chamber into said mixing zone at relative high flow velocities whereupon said first and second gases become intimately admixed in said gas mixing zone; and

. a header surrounding said ring for receiving and distributing said second gases into said conduits; and

d. means in said combustion zone for igniting said admixed gases.

10. The burner of claim 9 wherein said angle is from 045 upwards or downwards from the plane perpendicular to said axis.

1 l. The burner of claim 9 wherein each conduit is eccentrically arranged with respect of the central axis of said chamber so that said second gas passing through said conduits enter said mixing zone at a location eccentric to said axis to effect a swirling action of the first and second gases in said mixing zone.

12. The burner of claim 9 including means for regulating the flow velocities of said second gases into said mixing zone.

13. The burner of claim 9 wherein said first gas is a fuel gas and said second gas is air.

14. The burner of claim 13 including means for enriching said fuel gas with an enriching gas having a higher heating value than said fuel gas prior to its entry into said gas-mixing zone.

15. The burner of claim 9 wherein said first gas is air and said second gas is a fuel gas.

16. The burner of claim 9 wherein said chamber has a diameter that increases in the direction of gas flow therethrough so that as said admixed gases are ignited and burned their expansion may be accomodated effectively within said chamber whereby the combustion will be smoothly completed before the gases enter into said heat exchanger or furnace.

17. The burner of claim 9 including means for premixing said first gases with a portion of said second gases before said first gas enters said gas-mixing zone.

Claims

1. A burner for a top-fired blast furnace stove that has a checker chamber and a dome at the top thereof comprising: a. a burner chamber that is disposed at the top of said dome and that is symmetrically arranged about the central vertical axis of said dome; b. a first conduit communicating with the top of said burner chamber for carrying a combustion-supporting first gas and for axially introducing said first gas at relatively low flow velocities into said burner chamber; c. a header completely surrounding a portion of said burner chamber for receiving a combustion-supporting second gas; d. a burner ring between said burner chamber and said header having a plurality of generalLy radially extending conduits through said ring for radially introducing at relatively high flow velocities a plurality of streams of said second gas inwardly into said burner chamber; e. a second conduit communicating with said header for carrying said second gases and for introducing said second gases into said header; f. means in said burner chamber for igniting the first and second gases whereby the first and second gases become intimately admixed in said burner chamber and said admixed gases are burned to produce hot, exhaust gases.

9. A burner for use in conjunction with high temperature heat exchangers or furnaces comprising: a. a chamber having i. a gas-mixing zone, and ii. a combustion zone; b. means for introducing a combustion supporting first gas generally axially of said chamber into said mixing zone at relatively low flow velocities; c. said gas mixing zone including i. a burner ring that is comprised of a plurality of refractory segments; said ring segments having a plurality of generally radially arranged conduits that are inclined at an angle with respect to the central axis of said chamber for introducing a combustion-supporting second gas generally radially of said chamber into said mixing zone at relative high flow velocities whereupon said first and second gases become intimately admixed in said gas mixing zone; and ii. a header surrounding said ring for receiving and distributing said second gases into said conduits; and d. means in said combustion zone for igniting said admixed gases.

10. The burner of claim 9 wherein said angle is from 0-45* upwards or downwards from the plane perpendicular to said axis.

11. The burner of claim 9 wherein each conduit is eccentrically arranged with respect of the central axis of said chamber so that said second gas passing through said conduits enter said mixing zone at a location eccentric to said axis to effect a swirling action of the first and second gases in said mixing zone.