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US-12618556-B2 - Burner and boiler-burner assembly

US12618556B2US 12618556 B2US12618556 B2US 12618556B2US-12618556-B2

Abstract

A burner ( 1 ) installable to a furnace ( 9 ) for burning an air-fuel mixture and for generating a flame in the furnace ( 9 ), said burner ( 1 ) comprising a frame member ( 6 ) provided with an elongated combustion head ( 2 ) protruding from said frame member ( 6 ) and being adaptable inside the furnace ( 9 ), what in a view from the burner's ( 1 ) frame member ( 6 ) is a distal end ( 2 a ) of said combustion head ( 2 ) being adaptable to generate both a main flame (B) and a primary flame (E), said combustion head ( 2 ) comprising an outer, larger diameter channel ( 3 ) for a mixture ( 80 ) of combustion air and fuel, as well as a smaller diameter, inner channel ( 4 ), surrounded by said outer channel ( 3 ), for primary air ( 60 ) as well as for primary gas ( 70 ), whereby the inner channel ( 4 ) extends from the burner's frame member ( 6 ) to the distal end ( 2 a ) and comprises an inner tube ( 4, 41 ) for primary gas ( 70 ) and an outer tube ( 4; 42 ) surrounding said inner tube ( 4; 41 ), wherein a flow space ( 4; 43 ) for primary air ( 60 ) is provided between the outer side of the jacket ( 41 a ) of said inner tube and the inner side of the jacket of the outer tube, and which combustion head's ( 2 ) outer channel ( 3 ) extends from the burner's frame member ( 6 ) to the combustion head's distal end ( 2 a ) and can be provided with a supply of premixed air-fuel mixture ( 80 ) from the burner's frame member ( 6 ), or from that section of the combustion head ( 2 ) which is associated with the frame member and located, in the flowing direction of the premixed air-fuel mixture ( 80 ), upstream of a combustion chamber ( 90 ), for generating the main flame B). In said burner the space delimited by the outer wall ( 31 ) of the outer channel ( 3 ) and the jacket of the outer tube ( 42 ) of the inner channel ( 4 ) is constructed as a discharge channel ( 10 ) extending from the frame member ( 6 ) to the distal end ( 2 a ) of the combustion head ( 2 ), whereby the discharge end ( 10 a ) of said discharge channel is veered away from the longitudinal center line (P) of the combustion head ( 2 ) so that the center line ( 10 A) of said discharge end ( 10 a ), or an extension thereof, forms an inclined angle of incidence (t) with the combustion head's ( 2 ) longitudinal center line (P), said angle of incidence (t) being 90-140 degrees as said discharge end ( 10 a ) of the discharge channel ( 10 ) is viewed from the direction of the burner's ( 1 ) frame member ( 6 ), a flow controller ( 7 ) is provided in the flow space ( 4; 43 ) for primary air, at the distal end ( 2 a ) of the combustion head ( 2 ), for directing the flow of primary air ( 60 ) in the flow space ( 43 ) so that the primary air ( 60 ) flows from the flow controller ( 7 ) towards the mouth ( 43 a ) of the flow space ( 43 ), in the vicinity of the jacket ( 42 a ) of the outer tube ( 4; 42 ) of the inner channel ( 4 ), a plurality of nozzles ( 8 ) is provided in the inner tube ( 4; 41 ) of the inner channel ( 4 ), at the distal end ( 41 a ) of said inner tube ( 4 ) in the flowing direction of the primary gas ( 70 ), for directing the primary gas ( 70 ) into the flow space ( 4; 43 ), either upstream or downstream of the flow controller ( 7 ) in the flowing direction of the primary air ( 60 ).

Inventors

  • Joonas KATTELUS
  • Lassi Karvonen

Assignees

  • OILON TECHNOLOGY OY

Dates

Publication Date
20260505
Application Date
20230412

Claims (20)

  1. 1 . A burner ( 1 ) installable to a furnace ( 9 ) for burning an air-fuel mixture and for generating a flame in the furnace ( 9 ), said burner ( 1 ) comprising a frame member ( 6 ) provided with an elongated combustion head ( 2 ) protruding from said frame member ( 6 ) and being adaptable inside the furnace ( 9 ), a distal end ( 2 a ) of said combustion head ( 2 ), relative to the frame member being adaptable to generate both a main flame (B) and a primary flame (E), said combustion head ( 2 ) comprising an outer, larger diameter channel ( 4 ), surrounded by said outer channel ( 3 ), for a mixture ( 80 ) of combustion air and fuel, as well as a smaller diameter, inner channel ( 4 ), surrounded by said outer channel ( 3 ), for primary air ( 60 ) as well as for primary gas ( 70 ), whereby the inner channel ( 4 ) extends from the burner's frame member ( 6 ) to the distal end ( 2 a ) and comprises an inner tube ( 4 , 41 ) for primary gas ( 70 ) and an outer tube ( 4 ; 42 ) surrounding said inner tube ( 4 ; 41 ); wherein a flow space ( 4 ; 43 ) for primary air ( 60 ) is provided between the outer side of the jacket ( 41 a ) of said inner tube and the inner side of the jacket of the outer tube, and which combustion head's ( 3 ) outer channel ( 3 ) extends from the burner's frame member ( 6 ) to the combustion head's distal end ( 2 a ) and can be provided with a supply of premixed air-fuel mixture ( 80 ) from the burner's frame member ( 6 ), or from that section of the combustion head ( 2 ) which is associated with the frame member and located, in the flowing direction of the premixed air-fuel mixture ( 80 ), upstream of a combustion chamber ( 90 ), for generating the main flame (B), characterized in that the space delimited by an outer wall ( 31 ) of the outer channel ( 3 ) and the jacket of the outer tube ( 42 ) of the inner channel ( 4 ) is constructed as a discharge channel ( 10 ) extending from the frame member ( 6 ) to the distal end ( 2 a ) of the combustion head ( 2 ), whereby the discharge end ( 10 a ) of said discharge channel is veered away from the longitudinal center line (P) of the combustion head ( 2 ) so that the center line ( 10 A) of said discharge end ( 10 a ), or an extension thereof, forms an inclined angle of incidence (t) with the combustion head's ( 2 ) longitudinal center line (P), said angle of incidence (t) being 90-140 degrees as said discharge end ( 10 a ) of the discharge channel ( 10 ) is viewed from the direction of the burner's ( 1 ) frame member ( 6 ), a flow controller ( 7 ) is provided in the flow space ( 4 ; 43 ) for primary air, at the distal end ( 2 a ) of the combustion head ( 2 ), for directing the flow of primary air ( 60 ) in the flow space ( 43 ) so that the primary air ( 60 ) flows from the flow controller ( 7 ) towards a mouth ( 43 a ) of the flow space ( 43 ), in the vicinity of a jacket ( 42 a ) of the outer tube ( 4 ; 42 ) of the inner channel ( 4 ), a plurality of nozzles ( 8 ) are provided in the inner tube ( 4 ; 41 ) of the inner channel ( 4 ), at the distal end ( 41 a ) of said inner tube ( 4 ) in the flowing direction of the primary gas ( 70 ), for directing the primary gas ( 70 ) into the flow space ( 4 ; 43 ), either upstream or downstream of the flow controller ( 7 ) in the flowing direction of the primary air ( 60 ).
  2. 2 . A burner ( 2 ) according to claim 1 , characterized in that the outer wall ( 31 ) of the outer channel ( 3 ), which is simultaneously the outer wall ( 10 d ) of the discharge channel ( 10 ), veers outward from the longitudinal center line (P) of the combustion head ( 3 ) at the discharge end ( 10 a ), when said outer wall ( 10 d ) of the discharge channel ( 10 ) is seen from the direction of the frame member ( 6 ) of the burner.
  3. 3 . A burner ( 2 ) according to claim 1 , characterized in that an inner wall ( 10 c ) of the discharge channel ( 10 ), which is simultaneously the jacket of the outer tube ( 42 ) of the inner channel ( 4 ), veers outward from the longitudinal center line (P) of the combustion head ( 2 ) at the discharge end ( 10 a ), when said inner wall of the discharge channel ( 10 ), or jacket of the outer tube ( 42 a ), is seen from the direction of the frame member ( 6 ) of the burner.
  4. 4 . A burner according to claim 1 , characterized in that a mouth ( 23 ) of the combustion head ( 2 ) comprises a mouth ( 10 a ) of the discharge channel ( 10 ) and the mouth ( 43 a ) of the flow space ( 43 ).
  5. 5 . A burner ( 2 ) according to claim 1 , characterized in that the flow controller ( 7 ) comprises a plurality of vanes ( 7 1 , 7 2 , 7 3 . . . 7 n ), whose surface area and orientation, relative to the flow of primary air ( 60 ) passing through between the same, have been adapted to be such that the flow of primary air ( 60 ) is directed, downstream said vanes, towards a mouth of the flow space ( 43 ), discharging into the combustion chamber ( 90 ) co-directionally with the main flame (B).
  6. 6 . A burner according to claim 1 , characterized in that the flow controller ( 7 ) is made up of a circular shaped disc encircling the inner tube ( 4 ; 41 ), the plane of said disc being transversely directed with respect to a lengthwise direction of the inner tube ( 4 ; 41 ).
  7. 7 . A burner ( 1 ) according to claim 5 or 6 , characterized in that the flow controller ( 7 ) comprises a disc or vanes ( 7 1 , 7 2 , 7 3 . . . 7 n ), which is/are mounted to encircle the inner tube ( 41 ) of the inner channel ( 4 ) at an equal distance from a free end ( 41 A) of the inner tube, said disc or said vanes ( 7 1 , 7 2 , 7 3 . . . 7 n ) being at least partially transversely directed with respect to the flowing direction of the primary air ( 60 ).
  8. 8 . A burner ( 1 ) according to claim 7 , characterized in that the vanes ( 7 1 , 7 2 , 7 3 . . . 7 n ) of the plurality of vanes are at an angle of 20-90 degrees relative to the flowing direction of primary air ( 60 ).
  9. 9 . A burner ( 1 ) according to claim 1 , characterized in that the flow space ( 4 ; 43 ) enlarges in the direction of the mouth ( 43 a ) of the flow space ( 43 ), which mouth ( 43 a ) is encircled by the inner walls of the discharge channel ( 10 ) at the discharge end ( 10 a ).
  10. 10 . A burner ( 1 ) according to claim 1 , characterized in that the plurality of nozzles ( 8 ) in the proximity of a free end of the inner tube ( 4 ), are adapted to direct the primary gas ( 70 ) from the inner tube ( 4 ; 41 ) into the flow space ( 43 ) or to the mouth ( 43 a ) f the flow space ( 43 ) in the flowing direction of primary air ( 60 ) upstream or downstream of the flow controller ( 7 ) located at a free end ( 2 a ) of the combustion head of the flow space ( 43 ).
  11. 11 . A burner ( 1 ) according to claim 1 , characterized in that the discharge channel ( 10 ) is adapted to become narrower and to veer away, as viewed from a center line (P) of the combustion head, when proceeding in the traveling direction of the premixed air-gas mixture ( 80 ) towards a mouth of the discharge channel's ( 10 ) discharge end ( 10 a ).
  12. 12 . A burner according to claim 11 characterized in that the cross-sectional area of the discharge end ( 10 a ) of the discharge channel ( 10 ) diminishes in the traveling direction of the premixed air-gas mixture ( 80 ) when proceeding towards the mouth of the discharge end ( 10 a ) which remains outside the inner wall ( 10 c ) of the discharge channel ( 10 ).
  13. 13 . A burner ( 1 ) according to claim 11 , characterized in that the external wall ( 10 d ) of discharge end ( 10 a ) of the discharge channel ( 10 ) is located on such a circular arc which has a radius R, and the inner wall of the discharge end ( 10 a ) of the discharge channel ( 10 ) is located on such a circular arc which has a radius R 1 , whereby the centers of the radii R and R 1 are located outside the combustion head ( 2 ).
  14. 14 . A burner ( 1 ) according to claim 11 , characterized in that the discharge channel's ( 10 ) external wall ( 31 ) and the discharge channel's ( 10 ) internal wall ( 42 a ) are curving outward as viewed from the combustion head's center line (P) with a radii of curvature (R) and (R 1 ) being equal or unequal.
  15. 15 . A burner ( 1 ) according to claim 14 , characterized in that the internal wall ( 42 ) of the discharge end ( 10 a ) of the discharge channel ( 10 ), which has the radius of curvature (R 1 ), curves more vigorously outward, seen from the center line (P) of the combustion head, than the external wall ( 31 ) of the discharge end ( 10 a ) of the discharge channel ( 10 ), which has the radius of curvature R, whereby R 1 >R.
  16. 16 . A furnace-burner assembly for burning the air-fuel mixture ( 80 ) and for generating the flame (B, E) in a combustion chamber ( 90 ) present inside the furnace, said burner ( 1 ) having been defined in claim 1 and connected to a furnace ( 9 ) in such a way that a first section of the elongated combustion head ( 2 ) is located outside the furnace ( 9 ) or connectable to structures of the furnace ( 9 ) and a second section of the elongated combustion head ( 2 ) is located inside the furnace ( 9 ), which protrudes from a frame member ( 6 ) and which combustion head ( 2 ) has its first section left outside the furnace ( 9 ) or connected to structures of the furnace ( 9 ), characterized in that the main flame (B) is generable by conducting some premixed air-fuel mixture ( 80 ) into the discharge channel ( 10 ), from the mouth of discharge channel's discharge end ( 10 a ) said fuel-air mixture ( 80 ) discharges into the combustion chamber ( 90 ), whereby the center line ( 10 A), or its extension, of said discharge end ( 10 a ) forms an inclined angle of incidence (t), which angle (t) is about 90-140 degrees, with the longitudinal center line (P) of the combustion head ( 2 ), as well as also with the longitudinal center line ( 10 L) of the discharge channel ( 10 ), as said discharge end ( 10 a ) for the discharge channel ( 10 ) is viewed with the direction of the burner's 1 frame member 6 , and the primary flame (E) is generable by providing the flow space ( 4 ; 43 ) with the supply of primary air ( 60 ) from the burner's ( 1 ) frame member ( 6 ) or from that section of the combustion head ( 2 ) which is associated with the frame member and located, in the flowing direction of primary air ( 60 ), upstream of the combustion chamber ( 90 ), for conveying the flow of primary air ( 60 ) to the flow controller ( 7 ) which is adapted to direct the flow of primary air ( 60 ) to pass towards a mouth of the flow space ( 43 ) co-directionally with the main flame (B), and by providing an inner channel's ( 4 ) inner tube ( 4 ; 41 ) with the supply of primary gas ( 70 ) from the burner's ( 1 ) frame member ( 6 ) or from the section of the combustion head ( 2 ) which is located, in the flowing direction of primary air ( 60 ), upstream of the combustion chamber ( 90 ), whereby the nozzles of a plurality of nozzles ( 8 ) in the proximity of a free end ( 4 a ) of the inner tube ( 4 ; 41 ) are adapted to direct the primary gas ( 70 ) to discharge from the combustion head's mouth ( 2 a ) into the flow space ( 4 ; 43 ).
  17. 17 . A furnace-burner assembly according to claim 16 , characterized in that the primary gas ( 70 ) is delivered from the inner tube ( 4 ; 41 ) by means of the nozzles ( 8 ) into the flow space ( 4 ; 43 ) in the flowing direction of the primary air ( 60 ) upstream or downstream of the flow controller ( 7 ) located at a free end ( 43 a ) of the flow space ( 4 ; 43 ).
  18. 18 . A furnace-burner assembly according to claim 16 , characterized in that the discharge channel ( 10 ) becomes narrower and veers outward, as viewed from the center line (P) of the combustion head ( 2 ), when proceeding, in the traveling direction of the premixed air-gas mixture ( 80 ), towards the discharge channel's ( 10 ) discharge end ( 10 a ), whereby speed of said air-gas mixture ( 80 ) increases as it flows towards a mouth of the discharge channel's ( 10 ) discharge end ( 10 a ).
  19. 19 . A furnace-burner assembly according to claim 16 , characterized in that the flame's backflow, jointly with the flow controller ( 7 ), is adapted to direct the flow of primary air ( 60 ), proceeding by way of the flow controller ( 7 ), towards a mouth of the flow space ( 43 ) in the proximity of the outer tube's internal surface.
  20. 20 . A furnace-burner assembly according to claim 16 , characterized in that the intensity and stability of the primary flame (E) are controllable by adjusting the amount and speed of primary air ( 60 ) and primary gas ( 70 ).

Description

The invention relates to a burner according to the preamble of claim 1 capable of being installed in a furnace for burning a premixed air-fuel mixture. The invention relates also to a furnace-burner assembly according to claim 16 for burning a premixed air-fuel mixture. So-called premix burners are used for burning a mixture of premixed fuel and air. These burners are intended to attain low NOx emission levels. Particularly premix burners with a long combustion head, intended to attain low NOx emissions (less than 9 ppm NOx emissions in flue gases) without substantial oxygen excesses, are disclosed in the prior art, i.a. in the publication U.S. Pat. No. 6,238,206. This prior known burner model is provided with a combustion head associated with the frame and extending a long way into the interior of a furnace and the low NOx emissions require oxygen excesses of less than 12% or especially less than 6%. The biggest downside of this burner has nevertheless been found to be a continuously relatively high NOx emission level, not completely fulfilling the stringent emission standards of e.g. certain states in the United States provided that the burner is to be operated efficiently, in other words, with low oxygen excesses. The Applicant's own US application discloses this type of burner capable of reaching low emissions but being limited in its compatibility with commercially available furnaces. The invention is intended to provide an improvement regarding the foregoing prior art or at least to alleviate the drawbacks existing in the above-described prior art. Therefore, a first objective of the invention is to provide a high-efficiency burner installable to a furnace, as well as a furnace-burner assembly in which a premixed air-fuel mixture can be combusted by the burner with oxygen excesses of less than 3% in such a way that the average NOx emissions in flue gases remain below 15 ppm, and with oxygen excesses of less than 7% in such a way that the average NOx emissions in flue gases remain below 5 ppm. It was a particular objective of the invention to attain a NOx level of less than 2.5 ppm with oxygen excesses of less than 8% by means of flame stabilization and phasing of mixture ratios. A second objective of the invention was to provide a burner more readily installable to commercially available furnaces, as well as a furnace-burner assembly obtainable thereby. The above objectives are attained with a burner of claim 1 capable of being installed to a furnace for burning a premixed air-fuel mixture, as well as with a furnace-burner assembly of claim 16 for burning an air-fuel mixture and for generating a flame in a combustion chamber inside the furnace. More specifically, the invention relates to a burner of claim 1 installable to a furnace for burning an air-fuel mixture and for generating a flame in the furnace. The burner comprises a frame member provided with an elongated combustion head protruding from said frame member and being adaptable inside the furnace, what in a view from the burner's frame member is a distal end of said combustion head being adapted to generate both a main flame and a primary flame, said combustion head comprising an outer, larger diameter channel for a mixture of combustion air and fuel, as well as a smaller diameter, inner channel, surrounded by the outer channel, for primary air as well as for primary gas. Hence, the combustion head's inner channel extends from the burner's frame member to the distal end and comprises an inner tube for primary gas and an outer tube surrounding said inner tube, wherein a flow space for primary air is provided between the outer side of the jacket of said inner tube and the inner side of the jacket of the outer tube, andthe combustion head's outer channel extends from the burner's frame member to the combustion head's distal end and can be provided with a supply of premixed air-fuel mixture from the burner's frame member, or from that section of the combustion head which is associated with the frame member and located, in the flowing direction of the premixed air-fuel mixture, upstream of a combustion chamber, for generating a main flame (B). The space between the outer wall of the outer channel and the jacket of the outer tube of the inner channel is constructed as a discharge channel extending from the frame member to the distal end of the combustion head, whereby the discharge end of said discharge channel is turned away from the longitudinal center line of the discharge end so that the center line of said discharge end, or an extension thereof, forms an inclined angle of incidence with the combustion head's longitudinal center line, said angle of incidence being 90-140 degrees as said discharge end of the discharge channel is viewed from the direction of the burner's frame member. A flow controller is provided in the flow space for primary air, at the distal end, for directing the flow of primary air in the flow space so that the primary air f