(19)
(11)EP 1 426 681 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
31.08.2005 Bulletin 2005/35

(21)Application number: 03253635.1

(22)Date of filing:  09.06.2003
(51)Int. Cl.7F23D 14/00, F23C 9/00

(54)

Compact low NOx gas burner apparatus and methods

Kompakte Gasbrennvorrichtung mit niedrigem NOx und Verfahren

Brûleur à gaz compact à faible production de NOx et méthodes


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR

(30)Priority: 06.12.2002 US 313065

(43)Date of publication of application:
09.06.2004 Bulletin 2004/24

(73)Proprietor: JOHN ZINK COMPANY,L.L.C.
Tulsa, OK 74116 (US)

(72)Inventors:
  • Chung, I-Ping
    Tulsa, Oklahoma 74133 (US)
  • Chambers, Jesse Steven
    Skiatook, Oklahoma 74070 (US)
  • Schnepper, Carol Ann
    Tulsa, Oklahoma 74105 (US)
  • Poe, Roger L.
    Beggs, Oklahoma 74421 (US)
  • Jayakaran, Jaiwant D.
    Tulsa, Oklahoma 74137 (US)
  • Waibel, Richard T.
    Broken Arrow, Oklahoma 74014 (US)
  • Claxton, Michael G.
    Tulsa, Oklahoma 74135 (US)
  • Zimola, Marianne
    Owasso, Oklahoma 74055 (US)
  • Foote, Darin Robert
    Tulsa, Oklahoma 74112 (US)

(74)Representative: Roberts, Mark Peter 
J.A. Kemp & Co., 14 South Square, Gray's Inn
London WC1R 5JJ
London WC1R 5JJ (GB)


(56)References cited: : 
US-A- 2 918 117
US-A- 5 542 840
US-B1- 6 394 792
US-A- 5 284 438
US-A- 6 007 325
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to gas burner apparatus and methods for burning fuel gas-air mixtures whereby flue gases having low NOx content are produced.

    [0002] Emission standards are continuously being imposed by governmental authorities which limit the quantities of gaseous pollutants such as oxides of nitrogen (NOx) which can be emitted into the atmosphere. Such standards have led to the development of various improved gas burner designs which lower the production of NOx and other polluting gases. For example, methods and apparatus have been developed wherein all of the air and some of the fuel is burned in a first zone and the remaining fuel is burned in a second zone. In this staged fuel approach, an excess of air in the first zone acts as a diluent which lowers the temperature of the burning gases and thereby reduces the formation of NOx. Other methods and apparatus have been developed wherein flue gases are combined with fuel gas and/or fuel gas-air mixtures to dilute the mixtures and lower their combustion temperatures and the formation of NOx.

    [0003] US 6,007,325 discloses a burner apparatus having a burner quarl comprising horizontally extending passages which extend from an exterior surface of the quarl completely through to the bore. A primary fuel tip is positioned inside each passage. Notches are provided in the upper, outer surface of the quarl. A secondary fuel tip is provided in each notch.

    [0004] While the above described prior art methods and burner apparatus for producing flue gases having low NOx content have achieved varying degrees of success, there still remains a need for improvement in gas burner apparatus and methods of burning fuel gas whereby simple economical burner apparatus is utilized and low NOx content flue gases are produced. Further, the burner apparatus utilized heretofore to carry out the above described methods have generally been large, produce flames of long length and have low turn down ratios.

    [0005] Thus, there are needs for improved burner apparatus and methods which produce low NOx content flue gases and the burner apparatus are compact, have short flame lengths and have high turn down ratios.

    [0006] By the present invention compact low NOx gas burner apparatus and methods are provided which meet the needs described above and overcome the deficiencies of the prior art. That is, the present invention provides improved gas burner apparatus and methods for discharging mixtures of fuel gas and air into furnace spaces wherein the mixtures are burned and flue gases having low NOx content are formed therefrom. In addition, the compact burner apparatus of this invention are smaller than most prior art burner apparatus, have high turn down ratios and produce short flame lengths.

    [0007] A compact gas burner apparatus of one embodiment is basically comprised of a housing having an open end attached to a furnace space and means for introducing a controlled flow rate of air into the housing attached thereto. A refractory burner tile is attached to the open end of the housing having an opening formed therein for allowing air to pass from the housing into the furnace space. The burner tile includes a wall surrounding the opening which extends into the furnace space and forms a mixing zone within and above the wall. The exterior sides of the wall are divided into sections by a plurality of radially positioned baffles attached thereto with alternate sections having the same or different heights and slanting towards the opening at the same or different angles. Some or all of the sections, preferably every other section, have passageways formed therein for conducting primary fuel gas from outside the sections to within the wall. A primary fuel gas nozzle connected to a source of fuel gas can optionally be positioned within the opening and wall of the burner tile for mixing additional primary fuel gas with the air flowing through the burner tile. One or more fuel gas nozzles, preferably one for each external slanted wall section, connected to a source of fuel gas and positioned outside the wall of the burner are provided for discharging secondary fuel gas adjacent to one or more of the sections. One or more of the fuel gas nozzles, preferably every other fuel gas nozzle, also discharge primary fuel gas and flue gases into and through the primary fuel gas passageways whereby the secondary fuel gas mixes with flue gases in the furnace space, the mixture of secondary fuel gas and flue gases mixes with unburned air, primary fuel gas and flue gases flowing through the opening and wall of the burner tile and the resultant mixture is burned in the furnace space in a folded flame pattern.

    [0008] By the improved methods of the present invention a mixture of fuel gas and air is discharged into a furnace space wherein the mixture is burned in a folded flame pattern and flue gases having low NOx content are formed therefrom. A method of one embodiment basically comprises the steps of discharging the air into a mixing zone within and adjacent to a wall which extends into the furnace space and has exterior sides divided into alternating sections by a plurality of radially positioned baffles attached thereto. The alternating sections have the same or different heights and slant towards the opening at the same or different angles. One or more of the sections, preferably every other section of the alternating sections, have passageways formed therein for conducting a primary fuel gas and flue gases mixture from outside the sections to within the wall. A primary portion of the fuel gas is discharged from locations outside the wall and adjacent to the one or more wall sections having passageways formed therein so that the primary portion of the fuel gas is mixed with flue gases in the furnace space and the resulting primary fuel gas-flue gases mixture formed flows into the mixing zone within the wall by way of the one or more passageways to form a primary fuel gas-flue gases-air mixture which flows into the furnace space. Simultaneously, a secondary portion of the fuel gas is discharged from one or more locations outside the wall and adjacent to one or more of the wall sections so that the secondary portion of fuel gas mixes with flue gases in the furnace space and the secondary fuel gas-flue gases mixture formed is discharged into the primary fuel gas-flue gases-air mixture in a plurality of separate streams which enter and mix with the primary fuel gas-flue gases-air mixture to form a highly mixed fuel gas-flue gases-air mixture which bums in a folded flame pattern.

    [0009] The scope of the invention is defined in the appended claims.

    [0010] The objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows when taken in conjunction with the accompanying drawings, in which:-

    FIGURE 1 is a perspective view of the burner tile of the present invention which includes a wall divided into sections by a plurality of radial baffles with alternate sections having different heights and slanting towards the opening at different angles.

    FIGURE 2 is a side cross-sectional view of the burner apparatus of the present invention attached to a furnace wall including the burner tile of FIG. 1 with the view of the burner tile being taken along line 2-2 of FIG. 1.

    FIGURE 3 is a top view of the burner of FIG. 2 taken along line 3-3 of FIG. 2.

    FIGURE 4 is a side cross-sectional view of the burner tile taken along line 4-4 of FIG. 3.

    FIGURE 5 is a picture of the folded flame pattern produced by the burner apparatus and methods of this invention.



    [0011] Referring now to the drawings, a compact, low NOx, gas burner apparatus of the present invention is illustrated and generally designated by the numeral 10. As best shown in FIG. 2, the burner apparatus 10 is sealingly attached to the bottom wall 12 of a furnace space over an opening therein. While gas burner apparatus are commonly mounted vertically and fired upwardly as shown in FIG. 2, it is to be understood that the burner apparatus can also be mounted horizontally and fired horizontally or vertically and fired downwardly. The burner apparatus 10 is comprised of a housing 14 having an open end 16 and an open end 18. The housing 14 is attached to the furnace wall 12 by means of a flange 20 and a plurality of bolts 22 which extend through complimentary openings in the flange 20 and the wall 12. An air flow rate regulating register 24 is connected to the housing 14 at its open end 16 for regulating the flow rate of combustion air entering the housing 14. The furnace wall 12 includes an internal layer of insulating material 26 attached thereto, and the open end 18 of the housing 14 includes a burner tile 28 formed of flame and heat resistant refractory material attached thereto. As illustrated in FIG. 2, the interior surface of the insulating material 26 attached to the furnace wall 12 and the top of the base portion 30 of the burner tile 28 define a furnace space within which the fuel gas and air discharged by the burner apparatus 10 are burned. The burner tile 28 has a central opening 32 formed in the base portion 30 thereof through which air introduced into the housing 14 by way of the air register 24 is discharged. The burner tile 28 also includes a wall portion 34 which surrounds the opening 32 and extends into the furnace space. The burner tile 28 and the central opening 32 in the base portion 30 of the burner tile 28 as well as the housing 14 can take various shapes, e.g., circular, rectangular, square, triangular, polygonal or other shape. However, the burner apparatus 10 preferably includes a circular burner tile 28 having a circular opening 32 therein. The wall portion 34 is circular. Also, the housing 14 preferably includes a circular opening 18 therein and the housing is preferably cylindrical. However, the housing can also include a square opening 18 therein and can have square or rectangular sides 15. In a preferred embodiment as shown in FIG. 2, the opening 32 in the burner tile 28 is smaller than the interior sides 33 of the wall 34 thereof so that a ledge 35 is provided within the tile 28 which functions as a flame stabilizing surface.

    [0012] Referring now to FIG. 1, a perspective view of the burner tile 28 and the wall 34 thereof is shown. The interior sides of the wall 34 are vertical as best shown in FIG. 2. The exterior sides of the wall 34 are divided into a plurality of sections 36 and 38 by radially positioned baffles 40 with the alternate sections 36 and 38 having different heights and slanting towards the opening 32 at different angles as shown in the drawings.

    [0013] Referring now to FIG. 4, it can be seen that in a preferred embodiment the sections 36 have short heights and slant towards the opening 32 in the burner tile 34 at large angles as compared to the sections 38 which have taller heights and slant toward the opening 32 at smaller angles. As will now be understood and as shown in FIGS. 1-4, the sections 36 and 38 between the baffles 40 alternate around the wall 34. In the embodiment illustrated in the drawing, there are four of the sections 36 and four of the sections 38. Depending on the size of the burner, there can be more or less of the alternating sections with the totals being even numbers, e.g., 4, 6, 8, 10, etc.

    [0014] The alternating sections 36 have heights in the range of from about 0cm to about 41cm (about 0 inches to about 16 inches) and slant towards the opening 32 at an angle in the range of from about 0 degrees to about 90 degrees. The alternating sections 38 can have the same or different heights as the alternating sections 36 in the range of from about 5cm to about 41cm (about 2 inches to about 16 inches) and slant towards the opening 32 at the same or different angles in the range of from about 0 degrees to about 60 degrees. Preferably, the alternating sections 36 have heights in the range of from about 0cm to about 41cm (about 0 inches to about 16 inches) and slant in the range of from about 0 degrees to about 90 degrees and the alternating sections 38 have different heights in the range of from about 5cm to about 41cm (about 2 inches to about 16 inches) and slant differently in the range of from about 0 degrees to about 60 degrees. As shown best in FIGS. 2-4, the sections 36 each include a passageway 42 extending from the outside to the inside of the wall 34 through which fuel gas mixed with flue gases flow as will be described further hereinbelow.

    [0015] In a more preferred arrangement of the alternating sections 36 and 38, the first of the alternating sections have heights in the range of from about 5 inches to about 10 inches and slant towards the opening at an angle in the range of from about 10 degrees to about 30 degrees, and the second of the alternating sections have the same or different heights as the first of the alternating sections in the range of from about 6 inches to about 12 inches and slant towards the opening at the same or different angles in the range of from about 5 degrees to about 15 degrees.

    [0016] In a presently preferred arrangement, the first of the alternating sections have heights of about 7 inches and slant towards the opening at an angle of about 20 degrees, and the second of the alternating sections have heights of about 9 inches and slant towards the opening at an angle of about 10 degrees.

    [0017] As shown in FIGS. 2 and 3, a central primary fuel gas nozzle 44 can optionally be positioned within the opening 32 near the bottom of the burner tile 28. When used, the nozzle 44 is connected by a conduit 46 to a fuel gas manifold 48. The conduit 46 is connected to the manifold 48 by a union 50 and a conduit 52 connected to the manifold 48 is connected to a source of pressurized fuel gas. As shown in FIGS. 2 and 3, a venturi 37 can optionally be positioned around and above the nozzle 44 so that a fuel gas lean mixture of fuel gas and air is formed and combusted in and above the venturi 37. Also, the burner 14 can optionally include a plurality of nozzles 44 and venturis 37 in lieu of the single nozzle 44 and venturi 37.

    [0018] As best shown in FIGS. 2 and 3, positioned in spaced relationship on the surface 30 of the burner tile 28 adjacent to the bottoms of the sections 36 and 38 of the wall 34 are a plurality of secondary fuel gas discharge nozzles 54. The nozzles 54 are positioned adjacent the intersections of the sections 36 and 38 with the surface of the base portion 30 of the burner tile 28. The nozzles 54 are connected to fuel gas conduits 56 (FIG. 2) which are connected to the fuel gas manifold 48 by unions 58. The nozzles 54 positioned adjacent to the sections 38 include fuel gas discharge openings therein whereby secondary fuel gas is discharged in fan shapes substantially parallel and adjacent to the exterior surfaces of the sections 38. The nozzles 54 positioned adjacent to the sections 36 include fuel gas discharge openings therein whereby secondary fuel gas is discharged in fan shapes substantially parallel and adjacent to the exterior surfaces of the sections 36. As the secondary fuel gas discharged by the nozzles 54 flows over the surfaces of the sections 36 and 38, flue gases in the furnace space outside the burner tile 28 are mixed with the secondary fuel gas.

    [0019] The passageways 42 in the sections 36 are positioned adjacent to the nozzles 54 as illustrated best in FIG. 3. In addition to the fuel gas discharge openings for discharging secondary fuel gas parallel to the surfaces of the sections 36, the fuel gas nozzles 54 adjacent to the sections 36 and the passageways 42 formed therein include primary fuel gas discharge openings for discharging primary fuel gas into the interior of the opening 32 and the wall 34 of the burner tile 28. Because of the primary fuel gas jets flowing through the openings 42, furnace space flue gases outside of the burner tile 28 are drawn into and flow through the openings 42 with the primary fuel gas into the interior of the opening 32 and wall 34 of the burner tile 28.

    [0020] While the passageways 42 with primary fuel gas jets and flue gases flowing therethrough are preferably located in every other section as described above, it is to be understood that one or more passageways 42 with primary fuel gas jets and flue gases flowing therethrough can be utilized in the wall 34 of the burner tile 28.

    [0021] In addition to defining the sections 36 and 38, the baffles function to divide the secondary fuel gas and flue gases into a plurality of separate streams which enter and intimately mix with the primary fuel gas-flue gases-air mixtures discharged from within the wall 34 of the burner tile 28. The primary fuel gas-flue gases-air mixtures formed within the wall 34 are ignited while within the wall 34 and then flow out of the wall 34. The collisions of the secondary fuel gas-flue gases streams with the primary fuel gas-flue gases-air mixtures create a plurality of U-shaped or folded flames 60 as shown in FIG. 5. As is well known by those skilled in the art, one of the primary mechanisms that produce NOx in a combustion process is thermal NOx, i.e., the higher the flame temperature, the more NOx that is created. In the burner apparatus of this invention, the multiplicity of folded flames 60 shown in FIG. 5 allow the fuel gas to be rapidly mixed with flue gases prior to and during burning with air thereby reducing NOx. Also, the increased surface area of the folded and convoluted flames 60 causes flue gases to mix with the flames more effectively, and the breaks 62 in the flames that exist between the folds allow flue gases to further penetrate between the flames and mix therewith, all of which contribute to very low NOx production.

    [0022] In operation of the burner apparatus 10, fuel gas is introduced into the furnace space to which the burner 10 is attached and burned therein at a flow rate which results in the desired heat release. Air is also introduced into the burner housing 14 and a column of the air flows into the furnace space. The flow rate of air introduced into the furnace space is in the range of from about 0% to about 100% in excess of the flow rate of air required to form a stoichiometric mixture of air and fuel gas. Preferably, the flow rate of air is in excess of the stoichiometric flow rate of air by about 15%. Stated another way, the mixture of fuel gas and air discharged into the furnace space contains from about 0% to about 100% of excess air. As shown in FIG. 2, the column of air flows through the housing 14 and through the opening 32 in the burner tile 28 into the mixing zone formed within the interior and above the wall 34. While within the mixing zone, the air mixes with the primary fuel gas and flue gases discharged into the mixing zone by way of the passageways 42 and the fuel gas nozzles 54 positioned adjacent to the passageways 42 and optionally by way of the fuel gas nozzle 44. The resulting primary fuel gas-flue gases-air mixture containing a large excess of air is burned within and adjacent to the top of the burner tile 28 and the flue gases formed therefrom have very low NOx content due to the dilution of the fuel gas by the excess air and flue gases.

    [0023] The secondary fuel gas discharged in directions parallel to the surfaces of the sections 36 and 38 by the nozzles 54 are mixed with flue gases surrounding the burner tile 28. The resulting secondary fuel gas-flue gases mixtures are discharged into the primary fuel gas-air mixture flowing from the interior of the wall 34 in a plurality of separate streams which form a folded flame pattern and mix with the primary fuel gas-air mixture to form a highly mixed fuel gas-flue gases-air mixture. The fuel gas-flue gases-air mixture bums in a multiplicity of folded flames in the furnace space and produces flue gases of low NOx content due to the fuel gas being diluted by relatively cool excess air and flue gases.

    [0024] While the secondary fuel gas is preferably discharged by the nozzles 54 adjacent to the surfaces of all of the sections 36 and 38, it is to be understood that the secondary fuel gas can be discharged from one or more nozzles 54 adjacent to one or more of the sections 36 and 38.

    [0025] A method of this invention for discharging a mixture of fuel gas and air into a furnace space wherein the mixture is burned in a folded flame pattern and flue gases having low NOx content are formed therefrom is comprised of the steps of: (a) discharging the air into a mixing zone within and adjacent to a wall which extends into the furnace space and has exterior sides divided into alternating sections by a plurality of radially positioned baffles attached thereto, the alternating sections having the same or different heights and slanting towards the opening at the same or different angles and one or more of the alternating sections having a passageway formed therein for conducting a primary fuel gas and flue gases mixture from outside the section to within the wall; (b) discharging a primary portion of the fuel gas from locations outside the wall and adjacent to the one or more wall sections having passageways formed therein so that the primary portion of the fuel gas is mixed with flue gases in the furnace space and the resulting primary fuel gas-flue gases mixture formed flows into the mixing zone within the wall by way of said passageways to form a primary fuel gas-flue gases air mixture which flows into the furnace space; and (c) discharging a secondary portion of the fuel gas from one or more locations outside the wall and adjacent to one or more of the wall sections so that the secondary portion of fuel gas mixes with flue gases in the furnace space and the secondary fuel gas-flue gases mixture formed is discharged into the primary fuel gas-flue gases-air mixture in one or more separate streams formed by the radially positioned baffles which enter and mix with the primary fuel gas-flue gases-air mixture to form a highly mixed fuel gas-flue gases-air mixture which bums in the folded flame pattern.

    [0026] The above method can also include the optional step of introducing a portion of the primary fuel gas into the mixing zone within the wall of the burner tile whereby the primary fuel gas mixes with air therein.

    [0027] The fuel gas, flue gases and air discharged into the furnace space in accordance with step (b) can contain from about 0% to about 100% of excess air. The primary portion of fuel gas utilized in accordance with step (b) is in the range of from about 2% to about 40% by volume of the total fuel gas discharged into the furnace space and the secondary portion of fuel gas utilized in accordance with step (c) is in the range of from about 60% to about 98% by volume of the total fuel gas discharged into the furnace space.

    [0028] Another method of this invention for discharging a fuel gas and air mixture into a furnace space wherein the mixture is burned in a folded flame pattern and flue gases having low NOx content are formed therefrom is comprised of the following steps: (a) discharging a column of the air into the furnace space; (b) discharging a first portion of the fuel gas mixed with flue gases from the furnace space into the column of the air; and (c) discharging a second portion of the fuel gas mixed with flue gases from the furnace space into the column of air containing the first portion of the fuel gas mixed with flue gases in a plurality of separate streams from spaced locations around the column, the separate streams entering the column radially and burning therein along with the first portion of the fuel gas in separate folded flames surrounded by and mixed with flue gases and air.

    [0029] Yet another method of this invention for discharging a fuel gas and air mixture into a furnace space wherein the mixture is burned in a folded flame pattern and flue gases having low NOx content are formed therefrom is comprised of the following steps: (a) discharging said air into said furnace space; and (b) discharging said fuel gas mixed with flue gases from said furnace space into said air in two or more separate streams which enter the air and burn therein in one or more folded flames surrounded by and mixed with flue gases and air.

    [0030] In order to further illustrate the apparatus of this invention, its operation and the methods of the invention, the following examples are given.

    EXAMPLE 1



    [0031] A burner apparatus 10 designed for a heat release of 8,000,000 BTU per hour by burning natural gas having a caloric value of 913 BTU/SCF was fired into a furnace space. Pressurized fuel gas was supplied to the manifold 48 of the burner 10 at a pressure of about 33 psig and a flow rate of about 8765 SCF/hour. A 20% by volume portion of the fuel gas (1753 SCF/hour) was used as primary fuel gas and was discharged within the opening 32 and wall 34 of the burner tile 28 by the fuel gas discharge nozzle 44 and by the fuel gas discharge nozzles 54 positioned adjacent to the openings 42 in the wall 40 of the burner tile 28. The remaining portion of the fuel gas, i.e., the secondary portion (at a rate of 7012 SCF/hour) was discharged into the furnace space by the nozzles 54 in separate fuel gas streams mixed with flue gases.

    [0032] The rate of air introduced into the furnace space by way of the air register 24, the housing 14 and the burner tile 28 was at least 15% in excess of the stoichiometric air rate relative to the total fuel gas rate. The primary fuel gas-flue gases air mixture began to burn at the vicinity of the passages 42 and at the top of the burner tile wall 34. The fuel gas-flue gases mixtures discharged at different angles into the partially burning fuel gas-air-flue gases mixture at the top of the burner tile wall 34 intimately mixed with flue gases from the furnace space and remaining air therein and burned above the burner tile in a short flame having a folded flame pattern. Because of the dilution of the primary and secondary fuel gases with flue gases and excess air and the intimate mixing of the fuel gas-air-flue gases mixture, the burner had a high turn down ratio and produced very low NOx emissions. Finally, the burner apparatus 10 has compact dimensions (significantly smaller than other low NOx burners) and can be easily installed in existing furnaces.

    EXAMPLE 2



    [0033] In order to see the flame pattern produced by the burner apparatus 10 when operated as described in Example 1 above, a computer simulation program was utilized. The software used was obtained from Fluent Inc. of Lebanon, New Hampshire. The design of the burner was reconstructed in the simulation program in full three dimensional detail including all important features such as tile facets, fuel gas port drillings, flame holder tile ledge and complete air plenum configuration.

    [0034] A three dimensional model of the furnace in which the burner apparatus was tested was then prepared and the burner model was mounted in the furnace model exactly like the test burner and furnace utilized in Example 1 except that the air entered the housing from the side instead of the bottom. The flow spaces in the burner model were divided into small volumes using the finite volume method and boundary conditions were applied, e.g., fuel pressure, flow rates, etc. at the entrances of the burner model. The software then calculated and predicted the flow patterns as well as combustion reactions and the resulting flame pattern by iteratively calculating values for all the combustion and flow parameters in each of the small volumes.

    [0035] The calculations were repeated until the predicted error was reduced to a desired level and then the output (a table of values for each volume) was fed into a graphics software package that produced a profile of static temperatures at planes cut through the flame at elevations of interest. One such elevation is presented in FIG. 5.

    [0036] As shown in FIG. 5, the flame pattern includes eight folded flames 60 corresponding to the eight sections 36 and 38 of the burner tile having breaks 62 between the folds. The center flame 64 is produced by the burning of the fuel discharged from the fuel gas nozzle 44.

    [0037] As mentioned previously herein, the separate folded flames 60 allow the fuel gas to be rapidly mixed with flue gases prior to burning with air thereby reducing the flame temperature and production of NOx. Also, the increased surface of the folded flames 60 and the breaks 62 that exist between the folds allow flue gases to penetrate the flames and mix therewith to a greater degree than has heretofore been possible. Consequently, the NOx emissions content of the flue gases released to the atmosphere is very low.

    [0038] Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the scope of this invention as defined by the appended claims.


    Claims

    1. A compact gas burner apparatus (10) having a short flame length and a high turndown ratio for discharging, in use, a mixture of fuel gas and air into a furnace space wherein the mixture is burned and flue gases having low NOx content are formed therefrom comprising:

    a housing (14) having an open end (18) attachable to said furnace space;

    means (24) for introducing a controlled flow rate of said air into said housing attached thereto;

    a burner tile (28) attached to the open end (18) of said housing (14) having an opening (32) formed therein for allowing said air to flow therethrough and having a circular wall (34) surrounding said opening (32) which extends, in use, into said furnace space, the exterior sides of said wall (34) being divided into sections (36, 38) by a plurality of radially positioned baffles (40) attached thereto with alternate sections (36, 38) having different heights and slanting towards said opening (32) at different angles and one or more of the alternating sections (36) having a primary fuel gas passageway (42) formed therein for conducting primary fuel gas from outside said section (36) to within said wall (34); and

    a plurality of fuel gas nozzles (54) connected to a source of fuel gas and positioned outside said wall (34) of said burner tile (28) for discharging secondary fuel gas adjacent to said external slanted wall sections (36, 38) with one or more of said fuel gas nozzles (54) also, in use, discharging primary fuel gas mixed with flue gases into and through said primary fuel gas passageways (42) whereby, in use, said secondary fuel gas mixes with flue gases in said furnace space, the mixture of secondary fuel gas and flue gases mixes with unburned air, primary fuel gas and flue gases flowing through said opening (32) and wall (34) of said burner tile (28), and the resultant mixture is burned in said furnace space.


     
    2. The burner apparatus of claim 1 wherein a first (36) of said alternating wall sections has a short height and slants towards said opening (32) in said burner tile (28) at a large angle, the second (38) of said wall sections has the same or a taller height and slants towards said opening (32) at the same or a smaller angle and successive alternating sections (36, 38) have heights and angles which are the same as said first and second sections.
     
    3. The burner apparatus of claim 1 or 2, wherein said radially positioned baffles (40) attached to said burner tile (28) extend in directions parallel to the axis of said burner tile wall (34) whereby, in use, said secondary fuel gas and flue gases are divided into a plurality of separate streams which mix with said primary fuel gas and unburned air flowing through said opening (32) and wall (34) of said burner tile (28).
     
    4. The burner apparatus of claim 2, wherein said first (36) of said alternating sections have heights in the range of from about 0cm to about 41cm (about 0 inches to about 16 inches) and slant towards said opening (32) at an angle in the range of from about 0 degrees to about 90 degrees, and the second (38) of said alternating sections have the same or different heights as the first (36) of said alternating sections in the range of from about 5cm to about 41cm (about 2 inches to about 16 inches) and slant towards said opening (32) at the same or different angles in the range of from about 0 degrees to about 60 degrees.
     
    5. The burner apparatus of claim 2, wherein said first (36) of said alternating sections have heights in the range of from about 13cm to about 25cm (about 5 inches to about 10 inches) and slant towards said opening (32) at an angle in the range of from about 10 degrees to about 30 degrees, and the second (38) of said alternating sections have the same or different heights as the first (36) of said alternating sections in the range of from about 15cm to about 30cm (about 6 inches to about 12 inches) and slant towards said opening (32) at the same or different angles in the range of from about 5 degrees to about 15 degrees.
     
    6. The burner apparatus of claim 2, wherein said first (36) of said alternating sections have heights of about 18cm (about 7 inches) and slant towards said opening (32) at an angle of about 20 degrees, and the second (38) of said alternating sections have heights of about 23cm (about 9 inches) and slant towards said opening (32) at an angle of about 10 degrees.
     
    7. The burner apparatus of any one of claims 2 to 6, wherein said passageways (42) are located in said slanted wall sections (36) which have short heights and slant towards said opening (32) in said burner tile (28) at large angles, said passageways (42) being positioned whereby primary fuel gas discharged from said fuel gas nozzles (54) mixes with flue gases and flows through said passageways (42) into the interior of said wall of said burner tile (28) wherein the mixture mixes with air.
     
    8. The burner apparatus of any one of the preceding claims, wherein said burner tile (28), said opening (32) therein and the interior of said wall (34) of said burner tile (28) are substantially circular.
     
    9. The burner apparatus of any one of the preceding claims, wherein said open end (18) of said housing (14) is circular and said housing (14) is cylindrical.
     
    10. The burner apparatus of any one of the preceding claims, further comprising at least one primary fuel gas nozzle (44) connected to a source of fuel gas positioned within said opening (32) and wall (34) of said burner tile (28) for mixing additional primary fuel gas with said air flowing through said burner tile (28) and discharging the mixture into said furnace space, in use.
     
    11. The burner apparatus of claim 11, further comprising a venturi (37) positioned around and above said additional primary fuel gas nozzle (44).
     
    12. The burner apparatus of any one of the preceding claims, further comprising a flame stabilizing surface within said opening (32) of said burner tile (28).
     
    13. The burner apparatus of claim 4, wherein, in use, said separate streams of secondary fuel gas and flue gases mixed with said unburned air and primary fuel gas are burned in said furnace space in a folded flame pattern which produces flue gases having low NOx content.
     
    14. A method of discharging a fuel gas and air mixture into a furnace space by way of an opening (32) therein, wherein said mixture is burned in a folded flame pattern and flue gases having low NOx content are formed therefrom comprising the steps of:

    (a) discharging a column of said air into said furnace space by way of a circular wall (34) which extends into said furnace space and has exterior sides divided into alternating sections (36, 38) having different heights and slanting towards said opening (32) at different angles, said wall having at least one opening (42) therein for conducting a first portion of said fuel gas mixed with flue gases from outside said wall (34) to within said wall (34);

    (b) discharging a first portion of said fuel gas mixed with flue gases from said furnace space into said column of said air; and

    (c) discharging a second portion of said fuel gas mixed with flue gases from said furnace space into said column of air containing said first portion of fuel gas mixed with flue gases in a plurality of separate streams from locations outside said wall and adjacent to said alternating sections, said separate streams entering said column radially and burning therein along with said first portion of said fuel gas in separate folded flames surrounded by and mixed with flue gases and air.


     
    15. The method of claim 14 wherein said separate streams of step (c) enter said column radially at an upward and inward angle.
     
    16. The method of claim 14 or 15, which optionally further comprises the step of discharging a part of said first portion of said fuel gas into said column of air prior to step (a).
     
    17. The method of claim 14, 15 or 16, wherein said mixture of fuel gas and air discharged into said furnace space contains from 0% to about 100% of excess air.
     
    18. The method of claim 14, 15, 16 or 17, wherein said first portion of said fuel gas is in the range of from about 2% to about 40% by volume of the total fuel gas discharged into said column of air.
     
    19. The method of claim any one of claims 14 to 18, wherein said second portion of said fuel gas is in the range of from about 60% to about 98% by volume of the total fuel gas discharged into said column of air and fuel gas.
     
    20. The method of any one of claims 14 to 19, wherein said circular wall (34) is formed of refractory material and is part of a refractory tile having said opening (32) within said wall.
     
    21. The method of any one of claims 14 to 19, wherein a first (36) of said alternating wall sections has a short height and slants towards said opening (32) at a small angle, the second (38) of said wall sections has a taller height and slants towards said opening (32) at a larger angle and successive alternating sections have heights and angles which are the same as said first and second sections.
     
    22. The method of any one of claims 14 to 21, wherein said alternating sections (36, 38) are separated by a plurality of radially positioned baffles (40) attached thereto.
     
    23. The method of claim 22, wherein said second portion of fuel gas mixed with flue gases from said furnace space is discharged from two or more locations outside said wall (34) and adjacent to two or more sections (36, 38) having different heights and slanting towards said opening (32) at different angles so that said second portion of fuel mixes with flue gases in said furnace space and the second fuel gas-flue gas mixture formed is discharged into said first fuel gas-flue gas mixture in two or more separate streams formed by said radially positioned baffles.
     


    Ansprüche

    1. Kompakte Gasbrennervorrichtung (10) mit einer kurzen Flammenlänge und einem großen Arbeitsbereich, um im Betrieb ein Gemisch aus Brenngas und Luft in einen Ofenraum abzugeben, wobei das Gemisch verbrannt wird und Abgase mit niedrigem NOx-Gehalt daraus gebildet werden, umfassend:

    ein Gehäuse (14) mit einem offenen Ende (18), das an dem Ofenraum anbringbar ist;

    ein Mittel (24) zum Einführen einer kontrollierten Luftströmungsrate in das daran angebrachte Gehäuse;

    eine an dem offenen Ende (18) des Gehäuses (14) angebrachte Brennerkachel (28) mit einer darin ausgebildeten Öffnung (32), um zu ermöglichen, dass die Luft hindurchströmt, und mit einer kreisförmigen, die Öffnung (32) umgebenden Wand (34), die sich im Betrieb in den Ofenraum hinein erstreckt, wobei die äußeren Seiten der Wand (34) durch eine Mehrzahl von radial angeordneten, daran angebrachten Prallblechen (40) in Abschnitte (36, 38) unterteilt sind, wobei sich abwechselnde Abschnitte (36, 38) eine unterschiedliche Höhe aufweisen und zur Öffnung (32) hin in unterschiedlichem Winkel geneigt sind und einer oder mehr der abwechselnden Abschnitte (36) einen darin ausgebildeten Primärbrenngas-Durchgang (42) aufweist, um Primärbrenngas von außerhalb des Abschnitts (36) in das Innere der Wand (34) zu leiten; und

    eine Mehrzahl von Brenngasdüsen (54), die mit einer Brenngasquelle verbunden sind und außerhalb der Wand (34) der Brennerkachel (28) zur Abgabe von Sekundärbrenngas benachbart den äußeren geneigten Wandabschnitten (36, 38) angeordnet sind, wobei eine oder mehrere der Brenngasdüsen (54) im Betrieb auch Primärbrenngas, das mit Abgasen gemischt ist, in und durch die Primärbrenngas-Durchgänge (42) abgibt, wodurch im Betrieb das Sekundärbrenngas sich mit Abgasen im Ofenraum mischt, das Gemisch aus Sekundärbrenngas und Abgasen sich mit der unverbrannten Luft, dem Primärbrenngas und Abgasen, die durch die Öffnung (32) und die Wand (34) der Brennerkachel (28) strömen, mischt und das sich ergebende Gemisch im Ofenraum verbrannt wird.


     
    2. Brennervorrichtung nach Anspruch 1, wobei ein erster (36) der abwechselnden Wandabschnitte eine niedrige Höhe hat und sich zur Öffnung (32) in der Brennerkachel (28) hin in einem großen Winkel neigt, wobei der zweite (38) der Wandabschnitte dieselbe oder eine größere Höhe hat und sich zur Öffnung (32) hin in demselben oder einem kleineren Winkel neigt, und aufeinander folgende abwechselnde Abschnitte (36, 38) Höhen und Winkel aufweisen, die gleich dem ersten und zweiten Abschnitt sind.
     
    3. Brennervorrichtung nach Anspruch 1 oder 2, wobei die radial angeordneten Prallbleche (40), die an der Brennerkachel (28) angeordnet sind, sich in Richtungen erstrecken, die parallel zur Achse der Brennkachelwand (34) verlaufen, wodurch im Betrieb das Sekundärbrenngas und die Abgase in eine Mehrzahl von getrennten Strömen geteilt sind, die sich mit dem Primärbrenngas und unverbrannter Luft mischen, die durch die Öffnung (32) und die Wand (34) der Brennerkachel (28) strömt.
     
    4. Brennervorrichtung nach Anspruch 2, wobei die ersten (36) der abwechselnden Abschnitte eine Höhe im Bereich von etwa 0 cm bis etwa 41 cm (etwa 0 Zoll bis etwa 16 Zoll) haben und sich zur Öffnung (32) hin in einem Winkel im Bereich von etwa 0 Grad bis etwa 90 Grad neigen, und die zweite n (38) der abwechselnden Abschnitte dieselbe oder eine andere Höhe wie die ersten (36) der abwechselnden Abschnitte im Bereich von etwa 5 cm bis etwa 41 cm (etwa 2 Zoll bis etwa 16 Zoll) haben und sich zur Öffnung (32) hin in demselben oder einem anderen Winkel im Bereich von etwa 0 Grad bis etwa 60 Grad neigen.
     
    5. Brennervorrichtung nach Anspruch 2, wobei die ersten (36) der abwechselnden Abschnitte eine Höhe im Bereich von etwa 13 cm bis etwa 25 cm (etwa 5 Zoll bis etwa 10 Zoll) haben und sich zur Öffnung (32) hin in einem Winkel im Bereich von etwa 10 Grad bis etwa 30 Grad neigen und die zweiten (38) der abwechselnden Abschnitte dieselbe oder eine andere Höhe als die ersten (36) der abwechselnden Abschnitte im Bereich von etwa 15 cm bis etwa 30 cm (etwa 6 Zoll bis etwa 12 Zoll) haben und sich zur Öffnung (32) hin in demselben oder einem anderen Winkel im Bereich von etwa 5 Grad bis etwa 15 Grad neigen.
     
    6. Brennervorrichtung nach Anspruch 2, wobei die ersten (36) der abwechselnden Abschnitte eine Höhe von etwa 18 cm (etwa 7 Zoll) haben und sich zur Öffnung (32) hin in einem Winkel von etwa 20 Grad neigen und die zweiten (38) der abwechselnden Abschnitte eine Höhe von etwa 23 cm (etwa 9 Zoll) haben und sich zur Öffnung (32) hin in einem Winkel von etwa 10 Grad neigen.
     
    7. Brennervorrichtung nach einem der Ansprüche 2 bis 6, wobei die Durchgänge (42) in den geneigten Wandabschnitten (36) angeordnet sind, die niedrige Höhen haben und sich zur Öffnung (32) in der Brennerkachel (28) hin in einem großen Winkel neigen, wobei die Durchgänge (42) so angeordnet sind, dass Primärbrenngas, das aus den Brenngasdüsen (54) ausströmt, sich mit Abgasen mischt und durch die Durchgänge (42) in das Innere der Wand der Brennerkachel (28) strömt, wobei sich das Gemisch mit der Luft mischt.
     
    8. Brennervorrichtung nach einem der vorhergehenden Ansprüche, wobei die Brennerkachel (28), die darin befindliche Öffnung (32) und das Innere der Wand (34) der Brennerkachel (28) im Wesentlichen kreisförmig sind.
     
    9. Brennervorrichtung nach einem der vorhergehenden Ansprüche, wobei das offene Ende (18) des Gehäuses (14) kreisförmig ist und das Gehäuse (14) zylindrisch ist.
     
    10. Brennervorrichtung nach einem der vorhergehenden Ansprüche, weiter umfassend mindestens eine Primärbrenngasdüse (44), die mit einer Brenngasquelle verbunden ist und sich in der Öffnung (32) und der Wand (34) der Brennerkachel (28) befindet, zum Mischen von zusätzlichem Primärbrenngas mit der durch die Brennerkachel (28) strömenden Luft und zur Abgabe des Gemischs im Betrieb in den Ofenraum.
     
    11. Brennervorrichtung nach Anspruch 11, weiter umfassend eine Venturidüse (37), die um und über der zusätzlichen Primärbrenngasdüse (44) angeordnet ist.
     
    12. Brennervorrichtung nach einem der vorhergehenden Ansprüche, weiter umfassend eine Flammenstabilisierungsfläche in der Öffnung (32) der Brennerkachel (28).
     
    13. Brennervorrichtung nach Anspruch 4, wobei im Betrieb die getrennten Ströme an Sekundärbrenngas und Abgasen, gemischt mit der unverbrannten Luft und dem Primärbrenngas, in der Ofenöffnung in einem gefalteten Flammenmuster verbrannt werden, wodurch Abgase mit niedrigem NOx-Gehalt erzeugt werden.
     
    14. Verfahren zur Abgabe eines Gemischs aus Brenngas und Luft in einen Offenraum mittels einer darin befindlichen Öffnung (32), wobei das Gemisch in einem gefalteten Flammenmuster verbrannt wird und Abgase mit niedrigem NOx-Gehalt daraus gebildet werden, umfassend die Schritte:

    (a) Abgabe einer Luftsäule in den Ofenraum mittels einer kreisförmigen Wand (34), die sich in den Ofenraum erstreckt und Außenseiten aufweist, die in abwechselnde Abschnitte (36, 38) geteilt sind, welche unterschiedliche Höhen haben und sich zur Öffnung (32) hin in unterschiedlichem Winkel neigen , wobei die Wand mindestens eine Öffnung (42) zum Leiten einer ersten Menge an mit Abgasen gemischtem Brenngas von außerhalb der Wand (34) ins Innere der Wand (34) aufweist;

    (b) Abgabe einer ersten Menge an mit Abgasen aus dem Ofenraum gemischtem Brenngas in die Luftsäule; und

    (c) Abgabe einer zweiten Menge an mit Abgasen aus dem Ofenraum gemischtem Brenngas in die Luftsäule, enthaltend die erste Menge an mit Abgasen gemischtem Brenngas, in einer Mehrzahl von getrennten Strömen von Stellen außerhalb der Wand und benachbart den abwechselnden Abschnitten, wobei die getrennten Ströme radial in die Säule gelangen und darin zusammen mit der ersten Menge an Brenngas in getrennten, gefalteten Flammen, die von Abgasen und Luft umgeben und damit gemischt sind, verbrannt werden.


     
    15. Verfahren nach Anspruch 14, wobei die getrennten Ströme von Schritt (c) radial in die Säule in einem nach oben und nach innen gerichteten Winkel gelangen.
     
    16. Verfahren nach Anspruch 14 oder 15, das vor Schritt (a) weiter wahlweise den Schritt der Abgabe eines Teils der ersten Menge an Brenngas in die Luftsäule umfasst.
     
    17. Verfahren nach Anspruch 14, 15 oder 16, wobei das Gemisch aus Brenngas und Luft, das in den Ofenraum abgegeben wird, 0 % bis etwa 100 % Luftüberschuss enthält.
     
    18. Verfahren nach Anspruch 14, 15, 16 oder 17, wobei die erste Menge an Brenngas im Bereich von etwa 2 Vol.-% bis etwa 40 Vol.-% des gesamten Brenngases, das in die Luftsäule abgegeben wird, liegt.
     
    19. Verfahren nach einem der Ansprüche 14 bis 18, wobei die zweite Menge an Brenngas im Bereich von etwa 60 Vol.-% bis etwa 98 Vol.-% des gesamten Brenngases, das in die Säule aus Luft und Brenngas abgegeben wird, liegt.
     
    20. Verfahren nach einem der Ansprüche 14 bis 19, wobei die kreisförmige Wand (34) aus feuerfestem Material gebildet wird und Teil einer feuerfesten Kachel ist, deren Öffnung (32) sich in der Wand befindet.
     
    21. Verfahren nach einem der Ansprüche 14 bis 19, wobei ein erster (36) der abwechselnden Wandabschnitte eine niedrige Höhe hat und sich zur Öffnung (32) hin in einem kleinen Winkel neigt, wobei der zweite (38) der Wandabschnitte eine größere Höhe hat und sich zur Öffnung (32) hin in einem größeren Winkel neigt, und aufeinander folgende abwechselnde Abschnitte Höhen und Winkel aufweisen, die gleich dem ersten und zweiten Abschnitt sind.
     
    22. Verfahren nach einem der Ansprüche 14 bis 21, wobei die abwechselnden Abschnitte (36, 38) durch eine Mehrzahl von radial angeordneten, daran angebrachten Prallblechen (40) getrennt ist.
     
    23. Verfahren nach Anspruch 22, wobei die zweite Menge an Brenngas, das mit Abgasen aus dem Ofenraum gemischt ist, von zwei oder mehr Stellen außerhalb der Wand (34) und benachbart zu zwei oder mehr Abschnitten (36, 38) abgegeben wird, die unterschiedliche Höhen aufweisen und sich zur Öffnung (32) hin in unterschiedlichen Winkeln neigen, so dass die zweite Menge an Brennstoff sich mit Abgasen im Ofenraum mischt und das zweite gebildete Brenngas-Abgas-Gemisch in das erste Brenngas-Abgas-Gemisch in zwei oder mehr getrennten Strömen, die durch die radial angeordneten Prallbleche gebildet werden, abgegeben wird.
     


    Revendications

    1. Brûleur à gaz compact (10) ayant une courte longueur de flamme et un rapport de transformation élevé pour évacuer, en utilisation, un mélange de gaz combustible et d'air dans un espace de four dans lequel le mélange est brûlé et des gaz de combustion ayant une faible teneur en NOx sont formés à partir de celui-ci, comportant :

    un carter (14) ayant une extrémité ouverte (18) pouvant être relié audit espace de four,

    des moyens (24) pour introduire un débit commandé dudit air dans ledit carter relié à ceux-ci,

    un carneau de brûleur (28) relié à l'extrémité ouverte (18) dudit carter (14), ayant une ouverture (32) formée dans celui-ci pour permettre audit air de s'écouler à travers celui-ci et ayant une paroi circulaire (34) entourant ladite ouverture (32) qui s'étend, en utilisation, dans ledit espace de four, les côtés extérieurs de ladite paroi (34) étant séparés en tronçons (36, 38) par une pluralité de déflecteurs positionnés radialement (40) reliés à ceux-ci, les tronçons alternés (36, 38) ayant des hauteurs différentes et s'inclinant vers ladite ouverture (32) selon des angles différents et un ou plusieurs des tronçons alternés (36) ayant un passage de gaz combustible principal (42) formé dans ceux-ci pour conduire du gaz combustible principal depuis l'extérieur audit tronçon (36) vers l'intérieur de ladite paroi (34), et

    une pluralité de buses de gaz combustible (54) reliées à une source de gaz combustible et positionnées à l'extérieur de ladite paroi (34) dudit carneau de brûleur (28) pour évacuer du gaz combustible secondaire, adjacentes auxdits tronçons de paroi inclinés extérieurs (36, 38), une ou plusieurs desdits buses de gaz combustible (54) évacuant également, en utilisation, du gaz combustible principal mélangé avec les gaz de combustion dans et à travers lesdits passages de gaz combustible principal (42) de sorte que, en utilisation, ledit gaz combustible secondaire se mélange avec les gaz de combustion dans ledit espace de four, le mélange de gaz combustible secondaire et de gaz de combustion se mélange avec de l'air non brûlé, du gaz combustible principal et des gaz de combustion s'écoulant à travers ladite ouverture (32) et la paroi (34) dudit carneau de brûleur (28), et le mélange résultant est brûlé dans ledit espace de four.


     
    2. Brûleur selon la revendication 1, dans lequel un premier (36) desdits tronçons de paroi alternés a une courte hauteur et s'incline en direction de ladite ouverture (32) dudit carneau de brûleur (28) selon un angle important, le deuxième (38) desdits tronçons de paroi a la même hauteur ou une hauteur plus grande et s'incline en direction de ladite ouverture (32) selon le même angle ou un angle plus petit et les tronçons alternés successifs (36, 38) ont des hauteurs et des angles qui sont les mêmes que lesdits premier et second tronçons.
     
    3. Brûleur selon la revendication 1 ou 2, dans lequel lesdits déflecteurs positionnés radialement (40) fixés sur ledit carneau de brûleur (28) s'étendent dans des directions parallèles à l'axe de ladite paroi de carneau de brûleur (34) de sorte que, en utilisation, ledit gaz combustible secondaire et les gaz de combustion sont divisés en une pluralité de flux séparés qui se mélangent avec ledit gaz combustible principal et l'air non brûlé s'écoulant à travers ladite ouverture (32) et la paroi (34) dudit carneau de brûleur (28).
     
    4. Brûleur selon la revendication 2, dans lequel lesdits premiers (36) desdits tronçons alternés ont des hauteurs dans la plage d'environ 0 cm à environ 41 cm (environ 0 pouce à environ 16 pouces) et s'inclinent en direction de ladite ouverture (32) selon un angle dans la plage d'environ 0 degré à environ 90 degrés, et les seconds (38) desdits tronçons alternés ont les mêmes hauteurs, ou des hauteurs différentes, que les premiers (36) desdits tronçons alternés, dans la plage d'environ 5 cm à environ 41 cm (environ 2 pouces à environ 16 pouces) et s'inclinent en direction de ladite ouverture (32) selon le même angle ou des angles différents dans la plage d'environ 0 degré à environ 60 degrés.
     
    5. Brûleur selon la revendication 2, dans lequel lesdits premiers (36) desdits tronçons alternés ont des hauteurs dans la plage d'environ 13 cm à environ 25 cm (environ 5 pouces à environ 10 pouces) et s'inclinent en direction de ladite ouverture (32) selon un angle dans la plage d'environ 10 degrés à environ 30 degrés, et les seconds (38) desdits tronçons alternés ont la même hauteur, ou des hauteurs différentes, que les premiers (36) desdits tronçons alternés, dans la plage d'environ 15 cm à environ 30 cm (environ 6 pouces à environ 12 pouces) et s'inclinent en direction de ladite ouverture (32) selon le même angle ou des angles différents dans la plage d'environ 5 degrés à environ 15 degrés.
     
    6. Brûleur selon la revendication 2, dans lequel lesdits premiers (36) desdits tronçons alternés ont des hauteurs d'environ 18 cm (environ 7 pouces) et s'inclinent en direction de ladite ouverture (32) selon un angle d'environ 20 degrés, et les seconds (38) desdits tronçons alternés ont des hauteurs d'environ 23 cm (environ 9 pouces) et s'inclinent en direction de ladite ouverture (32) selon un angle d'environ 10 degrés.
     
    7. Brûleur selon l'une quelconque des revendications 2 à 6, dans lequel lesdits passages (42) sont situés dans lesdits tronçons de paroi inclinée (36) qui ont de courtes hauteurs et s'inclinent en direction de ladite ouverture (32) dudit carneau de brûleur (28) selon de grands angles, lesdits passages (42) étant positionnés de sorte que du gaz combustible principal évacué à partir desdits buses de gaz combustible (54) se mélange avec les gaz de combustion et s'écoule à travers lesdits passages (42) jusqu'à l'intérieur de ladite paroi dudit carneau de brûleur (28) dans lequel le mélange se mélange avec de l'air.
     
    8. Brûleur selon l'une quelconque des revendications précédentes, dans lequel ledit carneau de brûleur (28), ladite ouverture (32) située dans celui-ci et l'intérieur de ladite paroi (34) dudit carneau de brûleur (28) sont sensiblement circulaires.
     
    9. Brûleur selon l'une quelconque des revendications précédentes, dans lequel ladite extrémité ouverte (18) dudit carter (14) est circulaire et ledit carter (14) est cylindrique.
     
    10. Brûleur selon l'une quelconque des revendications précédentes, comportant de plus au moins une buse de gaz combustible principal (44) reliée à une source de gaz combustible positionnée dans ladite ouverture (32) et la paroi (34) dudit carneau de brûleur (28) pour mélanger du gaz combustible principal supplémentaire avec ledit air s'écoulant à travers ledit carneau de brûleur (28) et évacuer le mélange à l'intérieur dudit espace de four, en utilisation.
     
    11. Brûleur selon la revendication 10, comportant de plus un venturi (37) positionné autour et au-dessus de ladite buse de gaz combustible principal supplémentaire (44).
     
    12. Brûleur selon l'une quelconque des revendications précédentes, comportant de plus une surface de stabilisation de flamme dans ladite ouverture (32) dudit carneau de brûleur (28).
     
    13. Brûleur selon la revendication 4, dans lequel, en utilisation, lesdits flux séparés de gaz combusible secondaire et de gaz de combustion mélangés avec ledit air non brûlé et du gaz combustible principal sont brûlés dans ledit espace de four selon un motif de flamme plissée qui produit des gaz de production ayant une faible teneur en NOx.
     
    14. Procédé pour évacuer un mélange de gaz combustible et d'air dans un espace de four au moyen d'une ouverture (32) existant dans celui-ci, dans lequel ledit mélange est brûlé selon un motif de flamme plissée et des gaz de combustion ayant une faible teneur en NOx sont formés à partir de celui-ci, comportant les étapes suivantes :

    (a) évacuer une colonne dudit air à l'intérieur dudit espace de four au moyen d'une paroi circulaire (34) qui s'étend dans ledit espace de four et a des côtés extérieurs divisés en tronçons alternés (36, 38) ayant des hauteurs différentes et s'inclinant en direction de ladite ouverture (32) selon des angles différents, ladite paroi ayant au moins une ouverture (42) dans celle-ci pour conduire une première partie dudit gaz combustible mélangé avec des gaz de combustion depuis l'extérieur de ladite paroi (34) vers l'intérieur de ladite paroi (34),

    (b) évacuer une première partie dudit gaz combustible mélangé avec des gaz de combustion provenant dudit espace de four dans ladite colonne dudit air, et

    (c) évacuer une seconde partie dudit gaz combustible mélangé avec des gaz de combustion depuis ledit espace de four à l'intérieur de ladite colonne d'air contenant ladite première partie de gaz combustible mélangé avec des gaz de combustion selon une pluralité de flux séparés provenant d'emplacements à l'extérieur de ladite paroi et adjacents auxdits tronçons alternés, lesdits flux séparés eritrant radialement dans ladite colonne et brûlant dans celle-ci en même temps que ladite première partie dudit gaz combustible dans des flammes plissées séparées entourées par des gaz de combustion et de l'air et mélangées avec ceux-ci.


     
    15. Procédé selon la revendication 14, dans lequel lesdits flux séparés de l'étape (c) pénètrent radialement dans ladite colonne selon un angle dirigé vers le haut et vers l'intérieur.
     
    16. Procédé selon la revendication 14 ou 15, qui comporte de plus facultativement l'étape consistant à évacuer une partie de ladite première partie dudit gaz combustible dans ladite colonne d'air avant l'étape (a).
     
    17. Procédé selon la revendication 14, 15 ou 16, dans lequel ledit mélange de gaz combustible et d'air évacué dans ledit espace de four contient de 0 % à environ 100 % d'air en excès.
     
    18. Procédé selon la revendication 14, 15, 16 ou 17, dans lequel ladite première partie dudit gaz combustible est dans la plage d'environ 2 % à environ 40 % en volume du gaz combustible total évacué dans ladite colonne d'air.
     
    19. Procédé selon l'une quelconque des revendications 14 à 18, dans lequel ladite seconde partie dudit gaz combustible est dans la plage allant d'environ 60 % à environ 98 % en volume du gaz combustible total évacué dans ladite colonne d'air et de gaz combustible.
     
    20. Procédé selon l'une quelconque des revendications 14 à 19, dans lequel ladite paroi circulaire (34) est formée d'un matériau réfractaire et est une partie d'un carneau réfractaire ayant ladite ouverture (32) dans ladite paroi.
     
    21. Procédé selon l'une quelconque des revendications 14 à 19, dans lequel un premier (36) desdits tronçons de paroi alternés a une courte hauteur et s'incline en direction de ladite ouverture (32) selon un petit angle, le second (38) desdits tronçons de paroi a une hauteur plus grande et s'incline vers ladite ouverture (32) selon un angle plus grand et des tronçons alternés successifs ont des hauteurs et des angles qui sont les mêmes que lesdits premier et second tronçons.
     
    22. Procédé selon l'une quelconque des revendications 14 à 21, dans lequel lesdits tronçons alternés (36, 38) sont séparés par une pluralité de déflecteurs positionnés radialement (40) reliés à ceux-ci.
     
    23. Procédé selon la revendication 22, dans lequel ladite seconde partie de gaz combustible mélangé avec des gaz de combustion provenant dudit espace de four est évacuée à partir de deux ou plus de deux emplacements à l'extérieur de ladite paroi (34) et adjacents à deux ou plus de deux tronçons (36, 38) ayant des hauteurs différentes et s'inclinant en direction de ladite ouverture (32) selon des angles différents de sorte que ladite seconde partie de combustible se mélange avec des gaz de combustion dans ledit espace de four et le second mélange de gaz combustible et de gaz de combustion formé est évacué dans ledit premier mélange de gaz combustible et de gaz de combustion en deux ou plus de deux flux séparés formés par lesdits déflecteurs positionnés radialement.
     




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