Burner and furnace-burner assembly

Abstract

A burner mountable to a furnace for combusting an air-fuel mixture and generating a flame in the furnace, the burner comprising a frame member provided with an elongated combustion head protruding from the frame member and adapted to the interior of the furnace, the combustion head comprising a larger diameter outer pipe for combusting the mixture of air and fuel, and a smaller diameter inner pipe for primary air and primary gas surrounded by the outer pipe. A space delimited by the outer wall of the outer pipe and a sleeve of the outer pipe of the inner pipe is configured as a discharge channel extending from the frame member to a distal end of the combustion head. A flow controller is provided in the flow space for the primary air and at the distal end of the combustion head, a plurality of nozzles is provided in the inner pipe of the inner pipe and at a distal end of the inner pipe in the flow direction of the primary gas. Also a furnace-burner assembly for generating a flame in a combustion chamber present in the interior of a furnace.

Description

Technical Field

[0001] The present invention relates to a burner that can be installed in a furnace for combustion of a premixed air-fuel mixture.

[0002] The present invention also relates to a furnace-burner assembly for burning a premixed air-fuel mixture. Background Technology

[0003] So-called premixed burners are used to burn premixed fuel and air mixtures. These burners are designed to achieve low NOx emission levels. In particular, premixed burners with long burners designed to achieve low NOx emissions (less than 9 ppm NOx in flue gas) without a significant oxygen excess are disclosed in the prior art, specifically in publication US-6,238,206. This previously known burner model is configured with a burner head that is associated with a frame and extends a considerable distance into the interior of the furnace; low NOx emissions require an oxygen excess of less than 12%, and particularly less than 6%. However, the biggest drawback of this burner is the consistently relatively high NOx emission levels, which, even when the burner is operating effectively—in other words, with a low oxygen excess—cannot fully meet, for example, the stringent emission standards of some U.S. states. The applicant's own U.S. application discloses such a burner capable of achieving low emissions; however, this burner is limited in its compatibility with commercially available furnaces. Summary of the Invention

[0004] The present invention aims to provide improvements to, or at least mitigate, the disadvantages present in, the aforementioned prior art. Therefore, a first objective of the present invention is to provide a high-efficiency burner that can be installed on a furnace and a furnace-burner assembly in which a premixed air-fuel mixture can be combusted by the burner under conditions of less than 3% and less than 7% oxygen excess, maintaining average NOx emissions in the flue gas below 15 ppm under conditions of less than 3% oxygen excess and below 5 ppm under conditions of less than 7% oxygen excess. A particular objective of the present invention is to achieve NOx levels below 2.5 ppm under conditions of less than 8% oxygen excess by means of flame stabilization and staged mixing ratios.

[0005] A second object of the present invention is to provide a burner that can be more easily installed into a commercially available furnace, and the furnace-burner assembly thereby obtained.

[0006] The above-mentioned objective is achieved by the burner according to the invention and the furnace-burner assembly according to the invention, the burner being able to be installed in the furnace for combustion of a premixed air-fuel mixture, and the furnace-burner assembly for combustion of the air-fuel mixture and generation of flame in a combustion chamber inside the furnace.

[0007] More specifically, the present invention relates to a burner according to the invention, which can be installed in a furnace for burning an air-fuel mixture and producing a flame in the furnace. The burner includes a frame member having an elongated burner head projecting from the frame member and adaptable to the interior of the furnace. Viewed from the frame member of the burner, the distal end of the burner head is adapted to produce both a main flame and a primary flame. The burner head includes a larger-diameter outer conduit for burning the air-fuel mixture and a smaller-diameter inner conduit surrounded by the outer conduit for primary air and primary gas. Therefore, the internal conduit of the burner head extends from the frame member of the burner to the distal end and includes an internal tube for primary gas and an external tube surrounding the internal tube, wherein a flow space for primary air is provided between the outer side of the sleeve of the internal tube and the inner side of the sleeve of the external tube, the external conduit of the burner head extends from the frame member of the burner to the distal end of the burner head, and may be provided with a supply of premixed air-fuel mixture from the frame member of the burner or from a portion of the burner head associated with the frame member and located upstream in the flow direction of the premixed air-fuel mixture in the combustion chamber, for generating the main flame (B).

[0008] The space between the outer wall of the outer pipe and the sleeve-like component of the outer pipe of the inner pipe is constructed as follows: an exhaust channel extending from the frame member to the distal end of the burner head, wherein the exhaust end of the exhaust channel is turned away from the longitudinal centerline of the burner head, such that the centerline of the exhaust end or its extension forms an inclined angle of incidence with the longitudinal centerline of the burner head, and the angle of incidence is 90 degrees to 140 degrees when the exhaust end of the exhaust channel is viewed from the direction of the burner frame member.

[0009] A flow controller is provided at the distal end of a flow space for primary air to guide the flow of primary air within the flow space, causing the primary air to flow from the flow guide toward the opening of the flow space near the sleeve-shaped part of the outer tube of the inner channel.

[0010] Multiple nozzles are provided in the inner tube of the inner channel and at the distal end of the inner tube along the flow direction of the primary gas, for guiding the primary gas upstream or downstream of the flow controller along the flow direction of the primary gas into the flow space.

[0011] In the furnace-burner assembly of the present invention for burning an air-fuel mixture and generating a flame in a combustion chamber inside the furnace,

[0012] The burner, as previously defined and connected to the furnace, is such that: a second portion of an elongated burner head protruding from the frame member is provided inside the combustion chamber of the furnace, and a first portion of the burner head is located outside the furnace or connected to the furnace structure. A main flame is generated by guiding a premixed air-fuel mixture into an exhaust channel, the fuel-air mixture being discharged into the furnace from the outlet of the exhaust channel at an angle of 90 to 140 degrees when viewed from the centerline of the outlet at one end of the burner frame on one side.

[0013] The main flame (B) can be generated in the following ways:

[0014] By guiding the premixed air-fuel mixture into the exhaust channel, the fuel-air mixture is discharged into the combustion chamber from the outlet of the exhaust end of the exhaust channel. The centerline of the exhaust end forms an inclined angle of incidence with the longitudinal centerline of the burner head and the longitudinal centerline of the exhaust channel. When the exhaust end of the exhaust channel is viewed from the direction of the burner frame members, the angle of incidence is approximately 90 degrees to 140 degrees.

[0015] Primary Flame (E) can be generated in the following ways:

[0016] The primary air supply is provided to the flow space from the burner frame members, or from the portion of the burner head associated with the frame members and located upstream of the combustion chamber in the primary air flow direction, to deliver the flow of primary air to a flow controller adapted to direct the flow of primary air toward the opening of the flow space in the same direction as the main flame.

[0017] The supply of primary gas from the burner frame members or from the combustion chamber upstream of the combustion head in the primary air flow direction is provided to the internal tube of the internal pipe, wherein a nozzle among a plurality of nozzles located near the free end of the internal tube is adapted to guide the primary gas from the exhaust channel space of the combustion head.

[0018] This invention is based on a burner head consisting of two nested pipes. A premixed air-gas mixture passes through the outer pipe, i.e., the exhaust channel, thereby discharging the premixed air-gas mixture from the exhaust end of the exhaust channel into the combustion chamber. When viewed from the centerline of the burner head, the exhaust end of the exhaust channel narrows and turns. The cross-sectional area of ​​the exhaust channel gradually decreases in the direction of air-gas mixture propagation as it travels toward the opening at the exhaust end, which is located at the opening of the burner head.

[0019] The cross-section of the exhaust channel continuously decreases, reaching a minimum at the inlet. This allows the premixed air-gas mixture (the main flow) to continuously accelerate within the exhaust channel. Consequently, the main flow reaches its maximum velocity at the inlet.

[0020] Primary air and primary gas flow within the internal duct. The primary air is directed towards the burner head orifice via a flow controller, such as a blade, in the same direction as the main flame. The flow controller guides the primary air flow from the flow controller towards the orifice located near the sleeve of the outer tube of the internal duct within the flow space. In this way, the path of the primary air flowing from the flow controller towards the orifice of the flow space can be guided away from the centerline of the burner head, following the curvature of the inner wall of the exhaust passage.

[0021] The primary gas travels within its own tube in the internal pipe and is directed to the opening of the burner head through the nozzle.

[0022] In the burner, the intensity of the flame and the amount of air are precisely regulated, significantly impacting the main flame. This excellent adjustability makes the burner more compatible with a wider range of applications and combustion chambers than ever before. In particular, it is more compatible with water-tube boilers and other specialized applications.

[0023] Thanks to more reliable regulation, the new burner maintains an emission limit of 5 ppm and acceptable stability in a wider variety of combustion chambers than before. Furthermore, thanks to further optimization of flame stability and staged mixing ratios, this new concept achieves NOx levels of less than 2.5 ppm and oxygen excess of less than 8% (see also Table 1). The innovative burner head design minimizes the risk of backfire typical of premixed burners, thus improving safety and ease of use. Attached Figure Description

[0024] The invention and its benefits will now be described in more detail with reference to the accompanying drawings.

[0025] Figure 1 A cross-sectional view shows the frame components of a burner embodiment and the associated burner head.

[0026] Figure 2A An embodiment of a flow controller located at the burner head of a burner according to the invention is shown in an oblique front view.

[0027] Figure 2B Another embodiment of the flow controller located at the burner head of the burner according to the invention is also shown in a tilted front view.

[0028] Figure 2C Another embodiment of the flow controller located at the burner head of the burner according to the invention is shown in an oblique front view. Detailed Implementation

[0029] The following is a brief review of some aspects of the burner and furnace burner assembly of the present invention, which are in... Figure 1 , Figure 2A , Figure 2B and Figure 2C The Chinese text provides a detailed explanation.

[0030] Figure 1 The burner 1 is shown in longitudinal cross-section, with its burner head 2 extending into the furnace 9. The burner head 2 is typically cylindrical and has an annular cross-sectional profile. Figure 1 It also shows how flames A, B, C, D, and E are generated in the combustion furnace assembly by burning an air-fuel mixture 80 (generating the main flame B) directed to the orifice 23 of the burner head or burning primary air 60 or primary gas 70 (generating the primary flame E), with flames A, B, C, D, and E forming inside the furnace. Figure 1 Arrows indicate the direction of travel of the air-fuel mixture 80, primary air 60, and primary gas 70 in the combustion head 2.

[0031] Figure 1 The burner 1 is installed in the furnace 9 such that the opening 23 of the burner head 2 is open into the interior 90 of the furnace 9, and the frame member 6 of the burner is attached to the furnace 9 by a flange 91.

[0032] The elongated burner head 2 of burner 1 protrudes from the frame member 6 and has generated a main flame B and a primary flame E inside the furnace 9 at a depth of 90. The main flame B and the primary flame E are located downstream of the opening 23, which, when viewed from the frame member 6, is the distal end 2a of the burner head 2. The accumulation of other flame regions (A, C, D) will be described later.

[0033] The burner head 2 includes a larger diameter outer pipe 3 and a smaller diameter inner pipe 4 surrounded by the outer pipe 3. The outer pipe 3 is used for burning a mixture of air and fuel 80, and the inner pipe 4 is used for primary air 60 and primary gas 70.

[0034] The internal conduit 4 of the burner head 2, which is surrounded by the external conduit 3 of the burner head 2, is supplied with primary gas 70 and primary air 60. The internal conduit 4 of the burner head extends from the frame member 6 of the burner to the opening 23 of the distal end 2a of the burner head 2.

[0035] The internal conduit 4 of the burner head 2 includes an inner tube 4;41 and an outer tube 4;42. The inner tube 4;41 is used for gaseous fuel (primary gas) 70. The outer tube 4;42 surrounds the inner tube 4;41. A flow space 4;43 for primary air 60 is provided between the outer surface 41a of the sleeve 40 of the inner tube 41 (i.e., the side of the sleeve 41 of the inner tube 41 facing the outer tube 4;42) and the inner surface 42a of the sleeve 42 of the outer tube 4;42 (i.e., the side of the sleeve 40 of the outer tube facing the inner tube). The flow space 4;43 is therefore restricted in the direction of the outer conduit 3 by the sleeve of the outer tube 4;42 of the inner tube 4, so that the sleeve of the outer tube 4;42 of the inner tube 4 becomes the inner wall of the outer conduit 3.

[0036] The opening 23 of the burner head 2 is divided into the discharge end 10a of the discharge channel 10 and the combined opening 43a for the flow space 43, wherein the primary gas 70 flows through the internal tube 41 and the primary air 60 flows through the flow space 43.

[0037] The free end of the outlet 23 of the exhaust passage 10 facing the burner head 2 includes an exhaust end 10a, the outlet of which opens into the outlet 23 of the distal end 2a of the burner head 2. The exhaust passage 10 will be described in more detail below.

[0038] Viewed from the centerline of the burner head, i.e. in the radial direction of the burner head 2, the opening 43a of the flow space 43 of the internal channel 4 is restricted by the discharge end 10a of the discharge channel 10, and in particular by the distal end of the sleeve 42a of the external pipe 42.

[0039] The flow controller 7 is installed at the opening 43a of the flow space 43 of the internal pipe 4. Viewed from the frame member 6 of the burner 1, the flow controller 7 is located at the free end of the flow space, and the flow controller 7 forms part of the opening 23 of the distal end 2a of the burner head. Therefore, viewed from the frame member 6 of the burner, the flow controller 7 is located at the distal end 2a of the burner head 2, close to the opening 23 of the burner head.

[0040] The flow space 4;43 for primary air 60 extends from the frame member 6 of the burner 1 to the inlet 23, which is the distal end 2a of the burner head 2 (viewed from the frame member 6). The sleeve 42a of the outer tube 4;42 simultaneously forms the boundary surface between the inner tube 4 and the outer tube 3.

[0041] As described above, the sleeve 42a of the outer pipe 4;42 of the inner pipe 4 further separates the discharge end 10a of the discharge channel 10 and the opening 43a of the flow space 43 from each other at the opening 23 of the combustion head 2.

[0042] Viewed from the frame member 6 of the burner 1, the outer end 42A of the outer pipe 42 of the inner pipe 4, i.e., the free end 42A, is configured to turn outward, that is, from the longitudinal centerline of the burner head 2, it turns outward in the direction of the free end 31A of the outer wall 31 of the outer pipe 3. The center of the radius of curvature is located outside the burner head 2.

[0043] like Figure 1 As seen, the sleeve 42 of the outer tube 42 of the inner duct 4, which restricts the flow space 43, extends substantially parallel to the centerline P of the burner head 2, extending to the flow controller 7 located in the flow space 43 of the inner duct. The distal end 42A, i.e., the free end 42A, of the sleeve 42a of the outer tube 42 of the inner duct 4, extending downstream of the flow controller 7 in the flow direction of the primary air 60, turns away from the centerline P of the burner head 2 toward the outer wall 31 of the outer duct 3. In this way, the distal end 42A of the outer tube 42 of the inner duct 4 is guided away from the centerline P of the burner head 2 in the radial direction.

[0044] More precisely, the free end 42A of the outer wall of the sleeve 42a of the outer tube 42 of the internal pipe is located on a circular arc with a radius of R1, the center of which is located outside the burner head 2.

[0045] In this case, the distal end 42A or free end 42A of the outer pipe 42 of the inner pipe 4 refers to the portion of the outer pipe 42 located at the outer end 2a of the burner head 2 when viewed from the frame member 6 of the burner, which is approximately downstream of the flow controller 7.

[0046] When the primary air 60 leaves the flow space 43, the flow controller 7 guides the flow of the primary air 60 in the flow space 43 to pass in the same direction as the main flame B. The structure and function of the flow controller 7 are described in more detail below. Figures 2A to 2C As shown in the image.

[0047] The external conduit 3 of the burner head extends from the frame member of the burner 1 to the opening 23 of the distal end 2a of the burner head 2. The outer wall 31 of the external conduit 3 also constitutes the outer wall of the burner head 2. When viewed from the centerline 10L of the exhaust channel 10, the free end 3A of the external conduit 3—that is, the free end 31A of the outer wall of the external conduit—turns outward with a radius of curvature R, i.e., from the centerline P of the burner head (see...). Figure 1 During observation, the free end 3A of the external pipe 3 is turned away from the ground with a radius of curvature R. The center of the radius of curvature R is also preferably located outside the combustion head 2.

[0048] The space between the inner side 30 of the outer wall 31 of the outer pipe 3 and the outer side of the sleeve 42 of the inner pipe 42 forms an exhaust channel 10 in which a premixed air-fuel mixture 80 for generating the main flame B travels. The sleeve 42A of the outer pipe defines the inner pipe 4, thus simultaneously serving as the outer wall of the inner pipe 4. The exhaust channel 10 has a free end closer to the opening 23 of the burner head 2, which includes an exhaust end 10a, the opening of which is part of the opening 23 of the distal end 2a of the burner head 2.

[0049] Therefore, when the burner head is viewed from the direction of the frame member 6, the distal end 42A of the sleeve-shaped member 42a of the outer pipe 42 of the inner pipe 4, which is the inner surface of the discharge end 10a of the discharge channel 10, and the outer wall 31 of the outer pipe 3, which is the outer surface of the discharge end 10a of the discharge channel 10, turn toward each other and move away from the centerline P of the burner head. Therefore, the combustion end 10a has a trumpet-shaped appearance at the opening 23 of the burner head 2, and the cross-section of the discharge end 10a of the discharge channel 10 continuously decreases, reaching its minimum at the opening of the discharge channel 10.

[0050] This provides the following benefit: the premixed air-gas mixture (mainstream) is continuously accelerated at the discharge end 10a of the discharge channel. Therefore, the maximum flow rate of the mainstream is achieved at the opening of the discharge end 10a.

[0051] As described above, the free ends 31A and 42A of the outer wall 31 and inner wall of the exhaust channel 10—that is, the free ends of the sleeve-like member 42a of the outer tube 42—both have a "trumpet-shaped" overall appearance at the distal end 2a of the burner head 2. Therefore, the corresponding free ends 31A and 42A of the outer wall 31 and inner wall 42a of the exhaust channel 10 bend outward from the centerline 10L of the exhaust channel and the centerline P of the burner head, respectively, with radii of curvature R and R1, where R and R1 may be equal or unequal. The centers of these radii R and R1 are located outside the burner head.

[0052] In a preferred embodiment of the invention, when viewed from the frame member 6 of the burner, the centers of the radii of curvature R and R1 are located on one side of the cross-sectional plane of the centerline P of the burner head and face the opening 23 of the burner head 2, which extends approximately via the flow controller 7 located at the distal end of the burner head 2.

[0053] Since the free ends 31A of the outer wall 31 of the exhaust channel 10 and the free ends 42A of the inner wall 42a of the exhaust channel 10 are bent outward when viewed from the centerline 10L of the exhaust channel 10a and from the centerline P of the burner head 2, the entire exhaust end 10a is directed away when viewed from the centerline P of the burner head.

[0054] Since the emission channel 10a itself is annular, the centerline 10L of the emission channel here refers to the annular centerline 10L of the annular emission channel 10a as viewed in the longitudinal section of the emission channel (refer to...). Figure 1 Therefore, the angle of attack between the centerline 10L of the exhaust end 10a of the exhaust channel 10 (in the longitudinal section of the exhaust end) and the longitudinal centerline P of the burner head 2 is an angle of attack t. The same angle of attack 5 is also formed between the centerline 10A of the exhaust end 10a and the centerline 10L of the exhaust channel 10 (its longitudinal section). When the angle of attack 5 between the centerline 10A of the exhaust end and the longitudinal centerline P of the burner head, and the exhaust end 10a of the exhaust channel 10, is viewed from the direction of the frame member 6 of the burner 1, the angle of attack t is approximately 90-140 degrees.

[0055] Generally, the free end 42a of the inner wall 42 of the exhaust passage 10 with a radius of curvature R1 (the free end 42a of the outer pipe 42) arches more forcefully than the free end 31a of the outer wall 31 of the exhaust passage 10 with a radius of curvature R, where R > R1. Therefore, as the premixed air-gas mixture 80 travels towards the opening of the exhaust end 10a of the exhaust passage 10, the entire exhaust end 10a of the exhaust passage 10 becomes narrower and turns outward, and this opening is part of the opening 23 of the burner head (see reference). Figure 1 Therefore, as it moves toward the outlet end 10a located at the outlet 23 of the combustion head 2, the cross-sectional area of ​​the outlet end 10a of the discharge channel 10 decreases in the direction of travel of the premixed air-gas mixture 80.

[0056] This causes the flow velocity of the premixed air-gas mixture 80 flowing in the exhaust channel to be continuously accelerated as it passes through the opening toward the exhaust end 10a. The magnitude of the flow velocity and its acceleration will depend on the inclination angle 5 between the centerline 10A of the exhaust channel and the longitudinal centerline P of the burner head, as well as the relationship between the radii of curvature R and R1.

[0057] The novel design of the exhaust end 10a of the exhaust channel 10 minimizes the risk of typical premixed burner backfire, thereby improving safety and convenience of use.

[0058] The exhaust channel 10 of the external duct 3 is supplied with a premixed air-fuel mixture 80 for use in generating fuel. Figure 1 The main flame B is visible in the middle. The premixed air-fuel mixture 80 reaches the exhaust passage 10 of the external duct 3 from the frame member 6 or from the portion 2b of the burner head 2 that is associated with the frame member and is located upstream of the combustion chamber 90 in the flow direction of the premixed air-fuel mixture.

[0059] The distal end 41a of the internal conduit 4;41 is located in the flow direction of the primary gas 70, and this distal end is provided with a plurality of nozzles 8 for introducing the primary gas 70 into the flow space 4;43. ​​The primary gas is delivered into the flow space 43 upstream or downstream of the flow deflector 7 located at the free end 43 of the flow space 43, along the flow direction of the primary air 60. The internal pipe 4;41 of the internal conduit 4 provides the primary gas 70 from the frame member 6 of the burner 1 or from the portion 2b of the burner head 2 associated with the frame member and located upstream of the combustion chamber 90 in the flow direction of the primary gas 70.

[0060] When the flows of primary air 60 and primary gas 70 introduced into the flow space 43 merge with each other after the opening at the flow end of the flow space 43, a primary flame E is generated. The opening of the flow space is part of the opening 23 of the burner head 2.

[0061] Figure 2A , Figure 2B and Figure 2C The view, taken from a frontal oblique angle, shows the structure and functional selection of the flow controller 7 installed in the flow space 43 of the internal tube of the burner of the present invention. The flow of primary air 60 to the flow controller 8 and the flow of primary gas 70; 701 from the internal tubes 4; 41 to the same flow space 43 are further depicted in each figure.

[0062] like Figure 1 As shown, the flow of primary air 60 is adapted to flow from the burner frame member 6 into the flow space 43 and further through the flow controller 7.

[0063] The flow controller 7 used to guide the primary air 60 can have different designs and shapes; however, the most important aspect is that the flow of primary air 6 from the flow space 43 to the flow controller 7 is directed to the main flame B by the flow controller 7. The main flame is generated by the air-fuel mixture 80 flowing in the exhaust channel 10.

[0064] For example, Figure 2A As shown, the flow controller 7;7a may include multiple leaf-shaped sections 7 1 7 2 7 3 …7 n The leaf-shaped portion 7 of the flow controller 7;7a 1 7 2 7 3 …7 n It is mounted around the inner tube 41 at equal distances from the free end 41A of the inner tube 41. This is relative to the passage through two adjacent leaf-shaped portions (e.g., 7...). 1 and 7 2 Or 7 2 and 7 3 The primary airflow between 60 and 7 lobes, each lobed section 1 7 2 7 3 …7 n The surface area and orientation are adapted such that, downstream of the leaf-shaped portion 7, the flow of the primary air 60 is guided toward the opening 23 of the flow space 43 and simultaneously directed toward the opening of the burner head 2 in the same direction as the main flame B. Preferably, the flow of the primary air 60 is guided to the vicinity of the inner surface of the outer tubes 4, 42 by the action of the flow controller 7.

[0065] 7 foliate parts 1 7 2 7 3 …7 n The flow direction 60 relative to the primary air 60 in the flow space 43 is at least partially cross-oriented. Preferably, the leaf-shaped portion 7 1 7 2 7 3 …7 n It is positioned at an angle of 20 to 90 degrees relative to the flow direction of the primary air at 60 degrees.

[0066] exist Figure 2B In the flow controller 7;7b, a single circular disk surrounds the inner tube 41, and the plane of the disk is in the transverse direction relative to the longitudinal direction of the inner tube 41. The disk includes slots spaced apart from each other in the radial direction of the disk, thereby guiding the volume of primary air 60 flowing to the bottom surface of the disk from the slots to the opening 23 of the flow space 43 in the same direction as the main flame B.

[0067] Figure 2CAnother embodiment of the flow controller 7c is shown. The flow controller 7c includes a single circular disk surrounding an inner tube 41, and the plane of the disk is transverse relative to the longitudinal direction of the inner tube 41. The flow of primary air 60 reaching the bottom surface of the disk bypasses the disk and is guided toward the opening 23 of the flow space 43 in the same direction as the main flame B.

[0068] Next, referring to the previous... Figure 1 , Figure 2A , Figure 2B , Figure 2C The description further reviews some important details of the invention.

[0069] The flow space 4;43 increases as it travels toward the opening 23 of the burner head 2 because, when viewed from the centerline P of the burner head 2, the free end 42A of the sleeve 42 of the outer tube bends away.

[0070] It is thanks to reliable main flame B regulation that the burner can achieve emission limits of 5 ppm in multiple combustion chambers that were previously difficult to control, with acceptable stability. In addition, with further optimized flame stability and phase fixation of the air-fuel mixture, the new design enables NOx levels in the combustion chamber to reach <2.5 ppm (O2 reference value 3%).

[0071] To generate the primary flame E, the amount of primary air 60 supplied is 5% to 30% of the total air supplied to the burner head 2. Adjusting the relative amount and flow rate of the primary air 60 and primary gas 70 allows for precise control of the intensity of the primary flame E. This makes a major contribution to the intensity and stability of the main flame B. Preferably, the amount of primary air 60 supplied for generating the primary flame E is approximately 20% of the total amount of air used to generate the main flame B via the premixed air-fuel mixture 80 and used to generate the primary flame E via the primary air 60.

[0072] All premixed air and fuel are delivered to the location of the main flame B or to... Figure 1 Zone B of the main flame is where most of the combustion occurs. A primary flame E is generated at the inlet 23 of the burner head. The intensity and air volume of the primary flame E can be adjusted to create different temperatures for the flue gas flowing into Zone B of the main flame. This allows the burner's stability and emissions to be optimized for various applications and combustion chambers. With its excellent adjustability, this burner is more compatible with a wider range of applications and combustion chambers than before. In particular, it is more compatible than ever before with water-tube boilers and other specialized applications.

[0073] like Figure 1As observed, some combustion also occurs in flame zone A, with fuel and air ultimately entering flame zone A from zone B of the main flame. The flue gas circulates and cools within zone A. The cooled flue gas in zone A eventually returns to zone B, simultaneously lowering the main flame temperature and reducing NOx emissions from the burner. Some partially cooled flue gas also flows from zone C of flame C into zone B of the main flame, both diluting and cooling zone B, thus cooling the flame temperature distribution and further reducing NOx emissions from the burner.

[0074] A strong backflow exists in front of the inlet 23 of the burner head 2. Flue gas exits from zone B of the main flame along the wall of furnace 9, cooling simultaneously. A portion of the flue gas returns via a backflow DC through the middle section of combustion chamber 9. The backflow DC both cools and dilutes zone B established by the main flame. In zone D of the flame, at the end of combustion chamber 90, there is no significant backflow, but some complete combustion of carbon monoxide still occurs.

[0075] In the burner-furnace assembly according to the invention, the flame is significantly different from competing technologies due to the radial direction of the fluid. The flame becomes compact (wide and short), yet its volume remains remarkably large. Increasing the flame diameter has a greater impact on the flame volume than increasing its length. (Cylindrical volume = PI * (D / 2)^2).

[0076] Due to the shape of the flame, recirculation (A and D) is more effective at diluting and cooling the flame than competing technologies. These differences provide the advantage that the flame is cooled, resulting in lower NOx emissions.

[0077] If the burner is used with a high excess air, a smaller excess air volume is sufficient to meet the required NOx emissions. If the burner is used in conjunction with external flue gas recirculation (FGR), a smaller amount of recirculated flue gas is sufficient. Furthermore, a shorter flame is advantageous in many applications because a shorter furnace is often sufficient.

[0078] Using the exemplary burner-furnace combination according to the present invention, low NOx values ​​are achieved due to the design of the burner head and the shape of the resulting flame. Table 1 shows the NOx emissions [dry, mol-%] generated from the flue gas from the furnace based on excess oxygen.

[0079] Table 1:

[0080] excess oxygen

[0081]

[0082] Reference numerals for main components

[0083] Burner 1

[0084] Burner Head 2

[0085] distal end 2a

[0086] The portion 2b of the burner head located upstream of the combustion chamber

[0087] Mouth 23

[0088] External pipe 3

[0089] Free end 3A

[0090] outer wall 31

[0091] Internal 30

[0092] Free end 31A

[0093] Internal pipe 4

[0094] Internal tube 41

[0095] Sleeve 41a

[0096] Outer wall 40

[0097] External tube 42

[0098] Free end 42A

[0099] Sleeve 42a

[0100] Flow space 43

[0101] Free end 43a

[0102] Burner frame components 6

[0103] Flow controller 7

[0104] 7 foliate parts 1 , 7 2 , 7 3 ..7 n

[0105] Nozzle 8

[0106] Furnace 9

[0107] Internal combustion chamber 90

[0108] Flange 91 for the joint between the furnace and the burner

[0109] Emission channel 10

[0110] Discharge end 10a

[0111] Primary air 60

[0112] Primary air 602 emitted from the mouth

[0113] Primary gas 70

[0114] Primary gas 701 emitted into the flow space

[0115] Premixed air-fuel mixture 80

[0116] Reverse Flame A

[0117] Main Flame B

[0118] Side flame C immediately behind the primary flame

[0119] The side flames D further away behind the primary flame

[0120] Primary Flame E

[0121] longitudinal centerline P of the burner head

[0122] Radius of curvature R for the free end of the external pipe

[0123] Radius of curvature R1 for the free end of the outer tube

[0124] 10L centerline of the exhaust channel

[0125] Centerline 10A at the exhaust end.

Claims

1. A burner (1) capable of being mounted to a furnace (9) for burning a premixed air-fuel mixture and for generating a flame in the furnace (9), the burner (1) comprising a frame member (6) having an elongated burner head (2) protruding from the frame member (6) and adaptable to the interior of the furnace (9), wherein, as viewed from the frame member (6) of the burner (1), a distal end (2a) of the burner head (2) is adapted to generate both a main flame (B) and a primary flame (E), the burner head (2) comprising: A larger diameter outer pipe (3) for premixed air-fuel mixture (80), and a smaller diameter inner pipe (4) surrounded by said outer pipe (3) for primary air (60) and primary gas (70), thereby, The internal conduit (4) extends from the frame member (6) of the burner to the distal end (2a), and the internal conduit (4) includes an inner tube for primary gas (70) and an outer tube surrounding the inner tube, wherein a flow space for primary air (60) is provided between the outer side of the sleeve (41a) of the inner tube and the inner side of the sleeve of the outer tube, and the external conduit (3) of the burner head (2) extends from the frame member (6) of the burner to the distal end (2a) of the burner head, and the external conduit (3) of the burner head (2) is capable of being supplied with a premixed air-fuel mixture (80) from either the frame member (6) of the burner or from a portion of the burner head (2) associated with the frame member and located upstream of the combustion chamber (90) along the flow direction of the premixed air-fuel mixture (80) for generating the main flame (B). Its features are, The space defined by the outer wall (31) of the outer pipe (3) and the sleeve of the outer pipe (42) of the inner pipe (4) is constructed as follows: an exhaust channel (10) extending from the frame member (6) to the distal end (2a) of the burner head (2), wherein the exhaust end (10a) of the exhaust channel turns away from the longitudinal centerline (P) of the burner head (2), such that the centerline (10A) of the exhaust end (10a) or the extension of the exhaust end (10a) forms an inclined angle of incidence (t) with the longitudinal centerline (P) of the burner head (2), wherein the angle of incidence (t) is 90 degrees to 140 degrees when the exhaust end (10a) of the exhaust channel (10) is viewed from the direction of the frame member (6) of the burner (1). A flow controller (7) is provided in the flow space (43) for primary air and at the distal end of the burner head (2) to guide the flow of primary air (60) in the flow space (43) such that the primary air (60) flows from the flow controller (7) toward the opening (43a) of the flow space (43) near the sleeve (42a) of the outer pipe (42) of the inner pipe (4). A plurality of nozzles (8) are provided in the inner tube (41) of the inner pipe (4) and at the distal end of the inner tube (41) along the flow direction of the primary gas (70) for guiding the primary gas (70) upstream or downstream of the flow controller (7) along the flow direction of the primary air (60) into the flow space (43).

2. The burner (1) according to claim 1, characterized in that, When the outer wall (10d) of the exhaust channel (10) is viewed from the direction of the frame member (6) of the burner, the outer wall (31) of the outer pipe (3) which is the outer wall (10d) of the exhaust channel (10) turns outward from the longitudinal centerline (P) of the burner head (2) at the exhaust end (10a).

3. The burner (1) according to claim 1, characterized in that, When the inner wall (10c) of the exhaust channel (10) or the sleeve of the outer pipe (42) is viewed from the direction of the frame member (6) of the burner, the inner wall (10c) of the exhaust channel (10), which is the outer pipe of the inner pipe (4), turns outward from the longitudinal centerline (P) of the burner head (2) at the exhaust end (10a).

4. The burner (1) according to claim 1, characterized in that, The opening (23) of the burner head (2) includes the discharge end (10a) of the discharge channel (10) and the opening (43a) of the flow space (43).

5. The burner (1) according to claim 1, characterized in that, The flow controller (7) includes multiple leaf-shaped sections (7 1 7 2 7 3 …7 n The surface area and orientation of the flow of the primary air (60) through the blades relative to the primary air (60) are adapted such that the flow of the primary air (60) is directed downstream of the blades toward the opening of the flow space (43) and discharged into the combustion chamber (90) in the same direction as the main flame (B).

6. The burner (1) according to claim 1, characterized in that, The flow controller (7) is composed of a circular disk surrounding the inner tube (41), the plane of which is oriented laterally relative to the longitudinal direction of the inner tube (41).

7. The burner (1) according to any one of claims 1 to 6, characterized in that, The flow controller (7) includes a disk or blade (7 1 7 2 7 3 …7 n The disc or leaf-shaped portion is mounted such that: the inner tube (41) surrounds the inner pipe (4) at a distance equal to the free end (41A) of the inner tube (41), the disc or the leaf-shaped portion (7) 1 7 2 7 3 …7 n It is oriented at least partially relative to the flow direction of the primary air (60).

8. The burner (1) according to claim 7, characterized in that, The foliation of the plurality of said foliations (7) 1 7 2 7 3 …7 n The angle between 20 and 90 degrees is relative to the flow direction of the primary air (60).

9. The burner (1) according to any one of claims 1 to 6, characterized in that, The flow space (43) increases in the direction of the opening (43a) of the flow space (43), and the opening (43a) of the flow space (43) is surrounded by the inner wall of the discharge channel (10) at the discharge end (10a).

10. The burner (1) according to any one of claims 1 to 6, characterized in that, The nozzles included in the plurality of nozzles (8) near the free end of the inner tube (41) are adapted to guide the primary gas (70) from the inner tube (41) along the flow direction of the primary air and upstream or downstream of the flow controller (7) located at the distal end (2a) of the burner head in the flow space (43) into the flow space (43) or to the inlet (43a) of the flow space (43).

11. The burner (1) according to claim 1, characterized in that, The exhaust passage (10) is adapted to narrow as it travels along the direction of travel of the premixed air-fuel mixture (80) toward the opening of the exhaust end (10a) of the exhaust passage (10), and to turn away as observed from the longitudinal centerline (P) of the burner head.

12. The burner (1) according to claim 11, characterized in that, As the opening, which is located outside the inner wall (10c) of the discharge channel (10), travels toward the discharge end (10a), the cross-sectional area of ​​the discharge end (10a) of the discharge channel (10) decreases along the direction of travel of the premixed air-fuel mixture (80).

13. The burner (1) according to claim 11, characterized in that, The outer wall (10d) of the exhaust channel (10) at the exhaust end (10a) is located on an arc having a first radius of curvature (R), and the inner wall of the exhaust channel (10) at the exhaust end (10a) is located on an arc having a second radius of curvature (R1), wherein the center of the first radius of curvature (R) and the center of the second radius of curvature (R1) are located outside the burner head (2).

14. The burner (1) according to claim 13, characterized in that, As observed from the longitudinal centerline (P) of the burner head, the outer wall (10d) and the inner wall (10c) of the exhaust channel (10) are curved outward, wherein the first radius of curvature (R) and the second radius of curvature (R1) are equal or unequal.

15. The burner (1) according to claim 14, characterized in that, Observed from the longitudinal centerline (P) of the burner head, the inner wall (10c) of the exhaust channel (10) having the second radius of curvature (R1) at the exhaust end (10a) is more outwardly curved than the outer wall (10d) of the exhaust channel (10) having the first radius of curvature (R) at the exhaust end (10a), thereby the second radius of curvature (R1) is greater than the first radius of curvature (R).

16. A furnace-burner assembly for combusting a premixed air-fuel mixture (80) and for generating flames (B, E) in a combustion chamber (90) located inside the furnace of the furnace of the furnace-burner assembly. The burner (1) of the furnace-burner assembly is defined in claim 1, and the burner (1) is connected to the furnace (9) such that: inside the combustion chamber (90) of the furnace, a second portion of an elongated burner head (2) protruding from the frame member (6) is retained, the first portion of the burner head (2) being retained outside the furnace (9) or structurally connected to the furnace (9), characterized in that, Some main flames (B) can be generated by guiding a premixed air-fuel mixture (80) to the exhaust channel (10), discharging the premixed air-fuel mixture (80) from the outlet end (10a) of the exhaust channel into the combustion chamber (90), such that, when viewed from the direction of the frame member (6) of the burner (1), the centerline (10A) of the exhaust end (10a) or the extension of the exhaust end (10a) forms an inclined angle of incidence (t) with the longitudinal centerline (P) of the burner head (2), the angle of incidence (t) being approximately 90 to 140 degrees, and the centerline (10A) of the exhaust end (10a) or the extension of the exhaust end (10a) also forms an inclined angle of incidence (t) with the longitudinal centerline (10L) of the exhaust channel (10), and The primary flame (E) is generated by providing a supply of primary air (60) to the flow space (43), the supply originating from the frame member (6) of the burner (1) or from a portion of the burner head (2) associated with the frame member and located upstream of the combustion chamber (90) in the flow direction of the primary air (60), for conveying the flow of the primary air (60) to a flow controller (7), the flow controller being adapted to guide the flow of the primary air (60) through the opening of the flow space (43) in the same direction as the main flame (B), and The internal pipe (41) of the internal pipe (4) is provided with a supply of primary gas (70) which comes from the frame member (6) of the burner (1) or from the portion of the burner head (2) located upstream of the combustion chamber (90) in the flow direction of the primary air (60). Thus, the nozzle of the plurality of nozzles (8) near the free end (41A) of the internal pipe (41) is adapted to guide the primary gas (70) to be discharged from the mouth (2a) of the burner head into the flow space (43).

17. The furnace-burner assembly according to claim 16, characterized in that, The primary gas (70) is delivered from the inner tube (41) through the nozzle (8) and upstream or downstream of the flow controller (7) located at the free end of the flow space (43) in the flow direction of the primary air (60).

18. The furnace-burner assembly according to claim 16, characterized in that, When viewed from the longitudinal centerline (P) of the burner head (2), as the premixed air-fuel mixture (80) travels toward the discharge end (10a) of the discharge channel (10), the discharge channel (10) becomes narrower and deflects outward, thereby increasing the velocity of the premixed air-fuel mixture (80) as it flows toward the opening of the discharge end (10a) of the discharge channel (10).

19. The furnace-burner assembly according to claim 16, characterized in that, The backflow of the flame, together with the flow controller (7), is adapted to guide the flow of the primary air (60) traveling by means of the flow controller (7) toward the opening of the flow space (43) near the inner surface of the outer tube.

20. The furnace-burner assembly according to claim 16, characterized in that, The intensity and stability of the primary flame (E) can be controlled by adjusting the amount and speed of the primary air (60) and primary gas (70).

21. The furnace-burner assembly according to claim 16, characterized in that, The amount of primary air (60) supplied to generate the primary flame (E) is 5%-30% of the total air volume, which is used to generate the main flame (B) through the premixed air-fuel mixture (80) and to create the primary flame (E) by means of the primary air.

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