Dual-fuel turbulent burner capable of realizing uniform air intake and stable combustion

Abstract

The utility model discloses a dual-fuel turbulent burner capable of realizing uniform air intake and stable combustion, which belongs to the technical field of fuel cells and comprises a shell, a first baffle is arranged at one end of the shell, a fuel pipe penetrates through the center of the first baffle, an air flow equalizer is arranged on the inner side of the first baffle, the inner ring diameter of the air flow equalizer is larger than that of the fuel pipe, and air flow equalizing holes are formed in the inner ring wall of the air flow equalizer; a tail gas pipe is sleeved in the fuel pipe and extends out of the fuel pipe; a premixing air pipe sleeves the fuel pipe, one end of the premixing air pipe is connected with the cooling cylinder, and the other end of the premixing air pipe keeps a set distance from the air flow equalizer; a second baffle is arranged at the end, away from the fuel pipe, of the cooling cylinder, and a smoke cooling circular seam is reserved between the second baffle and the cooling cylinder. Air can enter the air flow equalizer in the radial direction or the axial direction and then evenly flow into the combustor, part of the air enters the premixed air channel and is evenly mixed with fuel after being subjected to rotational flow to form premixed fuel, and part of the air enters the cooling channel to cool high-temperature flue gas.

Description

Technical Field

[0001] This utility model belongs to the field of fuel cell technology, specifically relating to a dual-fuel swirl burner that achieves uniform air intake and stable combustion. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] In a fuel cell system, the burner is responsible for supplying heat during system startup and treating the anode exhaust gas of the fuel cell stack during steady-state operation. Therefore, the burner needs to have the functions of starting fuel and treating the anode exhaust gas of the fuel cell stack.

[0004] Typically, fuel flows into the burner radially, while air enters the burner in an axial direction or is injected at an angle. Different air intake methods can lead to significant differences in the uniformity of fluid mixing and flow distribution, thus failing to guarantee the stability of the combustion zone.

[0005] Patent CN117267730A discloses an integrated coal gasification fuel cell power generation system and its exhaust gas pure oxygen burner. It adopts an air radial back deflection to axial flow and a dual swirl flow mode for exhaust gas and oxygen to enhance the mixing effect of exhaust gas and oxygen. A jacket is set outside the flame tube, and a coolant is introduced into the jacket to cool the flame tube.

[0006] In the above scheme, the air enters the burner radially and then deflects into an axial flow, so the air cannot enter the burner evenly; cooling the flame tube externally cannot achieve the effect of cooling the high-temperature flue gas inside. Utility Model Content

[0007] To address the aforementioned issues, this invention provides a dual-fuel swirl burner that achieves uniform air intake and stable combustion. Air can enter the air equalizer radially or axially and then flow uniformly into the burner. Part of the air enters the premixed air channel and mixes uniformly with the fuel after swirl to form premixed fuel. Part of the air enters the cooling channel and cools the high-temperature flue gas through the flue gas cooling ring, flue gas cooling holes, and flame cooling holes. The fuel and the fuel cell anode exhaust gas adopt a sandwich design. The fuel cell anode exhaust gas enters the cooling cylinder through axial and radial discharge holes, and the premixed fuel formed by the fuel and air also enters the cooling cylinder. The premixed fuel and the fuel cell anode exhaust gas share the combustion space, which can save space.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A dual-fuel swirl burner for achieving uniform air intake and stable combustion includes a cylindrical shell, a first baffle at one end of the shell, and a fuel pipe passing through the center of the first baffle; an annular air equalizer is provided inside the first baffle, the inner ring diameter of the air equalizer is larger than that of the fuel pipe, and air equalization holes are uniformly arranged on the inner ring wall of the air equalizer.

[0010] An exhaust pipe is installed inside the fuel pipe. Inside the outer shell, the exhaust pipe extends out of the fuel pipe. The end of the fuel pipe is sealed and welded to the exhaust pipe. A premixed air pipe is installed outside the fuel pipe. One end of the premixed air pipe is flush with the end of the fuel pipe and is fixedly connected to the cooling cylinder. The other end is kept at a set distance from the air equalizer. A second baffle is installed at the end of the cooling cylinder away from the fuel pipe. A flue gas cooling annular gap is left between the second baffle and the cooling cylinder.

[0011] Preferably, the end of the exhaust pipe extending out of the fuel pipe is a distribution section, which is located inside the cooling cylinder and has multiple axial discharge holes and radial discharge holes.

[0012] Preferably, the plurality of axial discharge holes are disposed on the bottom surface of the end of the distribution section away from the fuel pipe, and are distributed in an array around the center of the bottom surface; the plurality of radial discharge holes are uniformly disposed in the circumferential direction of the distribution section.

[0013] Preferably, the first baffle has a through hole at its center, the diameter of which is the same as the diameter of the outer wall of the fuel pipe, and the fuel pipe is welded and fixed to the through hole at the center of the first baffle.

[0014] Preferably, the outer ring of the air equalizer is fixedly connected to the outer shell, the air equalizer is fixedly connected to the air intake pipe, and the air intake pipe is fixedly mounted on the outer shell.

[0015] Preferably, near the end where the premixed air pipe connects to the cooling cylinder, a plurality of swirl vanes are uniformly arranged between the premixed air pipe and the fuel pipe.

[0016] Preferably, the premixed air pipe has a premixed air channel inside, and a cooling air channel is formed between the outer wall of the premixed air pipe and the outer shell.

[0017] Preferably, inside the premixed air pipe, on the side of the swirl vane away from the cooling cylinder, a plurality of fuel holes are uniformly formed on the circumferential surface of the fuel pipe wall.

[0018] Preferably, the second baffle is welded and fixedly connected to the outer shell. The second baffle is a hollow ring with an inner ring diameter equal to the diameter of the cooling cylinder. An ignition channel is fixedly connected to the middle section of the cooling cylinder, and the ignition channel is fixedly installed on the outer shell.

[0019] Preferably, between the ignition channel and the second baffle, a plurality of flue gas cooling holes are uniformly arranged circumferentially on the wall of the cooling cylinder; a plurality of flame cooling holes are uniformly arranged circumferentially on the bottom surface of the end of the cooling cylinder connected to the premixed air pipe.

[0020] Compared with the prior art, the advantages and positive effects of this utility model are:

[0021] This invention utilizes an air equalizer to allow air to enter radially or axially and then flow evenly into the burner. A premixed air pipe is fitted over the fuel pipe; some air enters the premixed air channel within the premixed air pipe, while the rest flows to the cooling channel outside the cooling cylinder. The air in the cooling channel directly cools the high-temperature flue gas through the flue gas cooling annular seam, flue gas cooling holes, and flame cooling holes, preventing damage to the cooling cylinder. The flue gas cooling annular seam also releases localized stress caused by the expansion of the cooling cylinder due to high temperatures.

[0022] This invention features a tail gas pipe installed inside the fuel pipe, creating a sandwich design between the fuel and the fuel cell stack anode tail gas. The fuel cell stack anode tail gas enters the cooling cylinder through axial and radial discharge holes, while the fuel enters the premixed air pipe and mixes evenly with some air after swirling to form premixed fuel, which also enters the cooling cylinder. The premixed fuel and the fuel cell stack anode tail gas share the combustion space, saving space. Attached Figure Description

[0023] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0024] Figure 1 This is a cross-sectional view of the burner according to an embodiment of the present invention;

[0025] Figure 2 This is an embodiment of the present utility model. Figure 1 Right view with the flue gas cooling annular seam as the cross-section line;

[0026] In the picture:

[0027] 1. Outer shell; 11. First baffle; 12. Second baffle; 2. Exhaust pipe; 21. Distribution section; 211. Axial discharge port; 212. Radial discharge port; 3. Fuel pipe; 31. Fuel port; 4. Air equalizer; 41. Air intake pipe; 42. Air equalization port; 5. Premixed air pipe; 51. Swirl vane; 6. Cooling cylinder; 61. Flue gas cooling annular seam; 62. Ignition channel; 63. Flue gas cooling port; 64. Flame cooling port. Detailed Implementation

[0028] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] The present invention will now be described in detail with reference to the accompanying drawings. This embodiment discloses a dual-fuel swirl burner that achieves uniform air intake and stable combustion, such as... Figure 1 As shown, it includes a cylindrical outer shell 1, which is hollow inside. The two sides of the outer shell 1 are a fuel air inlet and a flue gas outlet, respectively. A first baffle 11 is provided at the fuel air inlet, and the first baffle 11 is tightly welded to the outer shell 1.

[0030] The first baffle 11 has a through hole in its center for the exhaust pipe 2 and the fuel pipe 3 to pass through. Parts of the fuel pipe 3 and the exhaust pipe 2 are inside the outer casing 1, and the other parts are outside the outer casing 1. It should be noted that the diameter of the fuel pipe 3 is larger than the diameter of the exhaust pipe 2. Figure 1 As shown, fuel pipe 3 is sleeved on the outside of exhaust pipe 2; the center of the bottom surface of fuel pipe 3 and exhaust pipe 2 is the same point as the center of the first baffle 11, forming a sandwich structure between fuel pipe 3 and exhaust pipe 2. The outer wall of fuel pipe 3 is welded and fixed to the central through hole of the first baffle 11. It can be understood that the diameter of the central through hole of the first baffle 11 is equal to the diameter of the outer wall of fuel pipe.

[0031] like Figure 1 As shown, inside the outer casing 1, the length of the exhaust pipe 2 is greater than the length of the fuel pipe 3. The fuel pipe 3 is located at the end of the outer casing 1, sealed, and welded to the exhaust pipe 2. The end of the exhaust pipe 2 without the fuel pipe 3 is a distribution section 21. The distribution section 21 has two types of fuel cell stack anode exhaust gas discharge ports: an axial discharge port 211 and a radial discharge port 212, as shown... Figure 1 , Figure 2 As shown, multiple axial discharge holes 211 are arranged on the bottom surface of the distribution section 21 on the side away from the fuel pipe 3, and are distributed in an array around the center of the bottom surface; multiple radial discharge holes 212 are evenly arranged in the circumference of the distribution section 21. The anode exhaust gas of the fuel cell stack flows out from the axial discharge holes 211 and the radial discharge holes 212 of the distribution section 21.

[0032] like Figure 1 As shown, an air equalizer 4 is installed outside the fuel pipe 3, located at the fuel-air inlet. The air equalizer 4 has a ring-shaped structure, with the inner ring having a larger diameter than the fuel pipe 3, and the outer ring being fixedly connected to the outer casing 1. An air inlet pipe 41 is fixedly connected to the air equalizer 4, and the air inlet pipe 41 is fixedly mounted on the outer casing 1. Air equalization holes 42 are evenly distributed on the inner ring wall of the air equalizer 4. It can be understood that air enters the air equalizer 4 through the air inlet pipe 41, and then is evenly injected into the outer casing 1 through the air equalization holes 42, meaning the air enters the burner evenly from all directions.

[0033] like Figure 1As shown, a premixed air pipe 5 is sleeved around the fuel pipe 3. The premixed air pipe 5 has openings at both ends, and the end of the premixed air pipe 5 furthest from the first baffle 11 is fixedly connected to the cooling cylinder 6. It can be understood that a connection hole of the same diameter as the outer wall of the premixed air pipe 5 is provided on the bottom surface of the cooling cylinder 6 at the connection end with the premixed air pipe 5 for fixed connection. The fluid in the premixed air pipe 5 enters the interior of the cooling cylinder through the connection hole. Near the end where the premixed air pipe 5 connects to the cooling cylinder 6, multiple swirl vanes 51 are evenly arranged between the premixed air pipe 5 and the fuel pipe 3. The fluid in the premixed air pipe 5 intersects at the swirl vanes, and then, after being turbulently mixed by the swirl vanes, enters the cooling cylinder for combustion.

[0034] like Figure 1 As shown, the end of the fuel pipe 3 inside the outer casing 1 is flush with the end of the premixed air pipe 5. The other end of the premixed air pipe 5 is kept at a set distance from the air equalizer 4. This set distance is set according to the actual situation to ensure that the air discharged from the air equalizer 4 into the burner can enter the premixed air pipe 5 evenly. Figure 1 As shown, the premixed air pipe 5 forms a premixed air channel inside, and a cooling air channel is formed between the outer wall of the premixed air pipe 5 and the outer shell 1.

[0035] like Figure 1 As shown, inside the premixed air pipe 5, on the side of the swirl vane 51 away from the cooling cylinder 6, the fuel pipe 3 has multiple fuel holes 31 on its wall. The fuel holes 31 are evenly distributed around the circumference of the fuel pipe 3. Fuel flows into the premixed air pipe 5 through the fuel holes 31, then mixes with the air flowing from the air equalizer 4. The mixture intersects at the swirl vane, and after being turbulently mixed by the swirl vane, it forms a uniformly distributed premixed fuel, which then enters the cooling cylinder for combustion.

[0036] Within the burner, air is divided into cooling air and premixed air. Cooling air flows into the cooling air passage, while premixed air flows into the premixed air passage. Understandably, the distribution ratio between the two is determined by the cross-sectional area ratio of the premixed air passage and the cooling air passage, as well as the pressure drop in subsequent passages. The amount of premixed air in the premixed fuel depends on the burner's load regulation ratio and the temperature range of the fuel cell anode exhaust gas. When the burner's load regulation ratio increases, the amount of premixed air decreases, and to shorten the flame, the corresponding swirl number increases; conversely, when the fuel cell anode exhaust gas temperature range increases, the amount of premixed air decreases, and to shorten the flame, the corresponding air swirl number increases.

[0037] The structural design of the swirl vane 51 is related to the swirl number S. The larger the swirl number, the stronger the swirl ability. Although swirl can enhance the mixing of the diffusion combustion process and strengthen the flame stability, when it exceeds a certain value A, the flame will be blown out due to the excessive excess air coefficient. When the swirl number is less than B, the swirl effect will be weakened.

[0038] In this embodiment, the design of the swirl vanes refers to the following formula: The inner and outer radii of the swirl vane are R and R1, respectively, and the tilt angle is α. The swirl number is generally taken to be between B and A, where B is usually 0.6 or greater than 0.6, and A is usually ≤6. It is optimized to A≤3, etc. The specific values ​​can be calculated through experiments and numerical simulations.

[0039] like Figure 1 As shown, the distribution section 21 is located inside the cooling cylinder 6. The anode exhaust gas of the fuel cell stack flows into the cooling cylinder 6 from the axial discharge port 211 and the radial discharge port 212 of the distribution section 21, and then mixes with the premixed fuel or air entering it, and burns near the end of the distribution section.

[0040] In this embodiment, the premixed fuel combustion zone overlaps with the fuel cell stack anode exhaust gas combustion zone, which can reduce the combustion space and achieve a smooth transition between the two fuels. At the end of the distribution section, the fuel cell stack anode exhaust gas is injected into the fuel cell stack anode exhaust gas combustion zone through two methods: radial jet and axial jet. The radial jet maintains the stability of the flame, while the axial jet mixes with the swirling air to enhance combustion and shorten the flame length.

[0041] A second baffle 12 is provided at the end of the cooling cylinder 6 away from the premixed air pipe 5, and the second baffle 12 is welded and fixed to the outer shell 1. The second baffle is a hollow annular shape, and its inner ring diameter is equal to the diameter of the cooling cylinder. It should be noted that the cooling cylinder 6 and the second baffle 12 are not connected, but a flue gas cooling annular gap 61 is left. The cooling air, blocked by the second baffle 12, passes through the flue gas cooling annular gap 61 to cool and lower the high-temperature flue gas that has just exited the cooling cylinder. During combustion, the cooling cylinder is prone to expansion due to high temperature, generating strong local stress, which may induce welding failure. In this embodiment, by setting the flue gas cooling annular gap, this stress can be released when the cooling cylinder expands under high temperature.

[0042] like Figure 1 As shown, an ignition channel 62 is fixedly connected to the middle section of the cooling cylinder 6. The ignition channel is fixedly installed on the outer shell, and the mixed fluid inside the cooling cylinder 6 is ignited through the ignition channel 62. Between the second baffle and the ignition channel, a plurality of flue gas cooling holes 63 are evenly arranged circumferentially on the cylinder wall of the cooling cylinder 6. On the bottom surface of the end of the cooling cylinder 6 connected to the premixed air pipe 5, a plurality of flame cooling holes 64 are evenly arranged circumferentially. The cooling air cools and lowers the temperature of the high-temperature flue gas inside the cooling cylinder through the flue gas cooling holes 63 and the flame cooling holes 64, avoiding the burning of the cooling cylinder by the high-temperature flue gas and extending the service life of the cooling cylinder.

[0043] It is understandable that multiple connecting rods can be welded to the side wall of the cooling cylinder 6 where it connects to the premixed air pipe 5, and the other end of the connecting rods can be welded and fixed to the outer shell 1, thereby enhancing the stability of the cooling cylinder 6.

[0044] Working principle:

[0045] During the system startup phase, premixed fuel combustion provides the heat required. As the system operates, the fuel is gradually switched to fuel stack anode exhaust gas.

[0046] During the start-up phase, air is blown into the air equalizer from the air connection pipe, enters the burner evenly, and then enters the cooling air passage and the premixed air passage respectively.

[0047] Fuel is introduced into fuel pipe 3 and enters the premixed air passage through fuel hole 31 to premix with air. After being turbulent by swirl vanes, it is mixed and then enters the cooling cylinder, where it is ignited at the end of the distribution section.

[0048] As the fuel is gradually switched to fuel cell anode exhaust gas, the fuel cell anode exhaust gas enters the cooling cylinder through the axial and radial exhaust holes at the end of the distribution section to participate in combustion; the radial jet can maintain the stability of the flame, and the axial jet, after mixing with the swirling air, enhances combustion and shortens the flame length;

[0049] During combustion, the cooling air in the cooling air channel cools the high-temperature flue gas from the combustion of the cooling cylinder by passing through the flue gas cooling ring gap, flue gas cooling hole, and flame cooling hole.

[0050] The burner in this embodiment is designed with a structure that evenly distributes air and fuel, which reduces the impact of the air and fuel intake scheme on the layout design and makes the layout design of the fuel cell system more convenient. This utility model takes into account the temperature difference between the high-temperature flame and the cooling air, which can cause local stress inside the cooling cylinder. Therefore, an air ring gap is left between the cooling cylinder and the second baffle to fully release the stress.

[0051] In this embodiment, the premixed fuel and the fuel cell anode exhaust gas share the combustion space, which saves space; the swirling premixed fuel combustion and the swirling diffusion combustion of the fuel cell anode exhaust gas effectively shorten the combustion flame and facilitate the burner layout design.

[0052] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A dual-fuel swirl burner that achieves uniform air intake and stable combustion, characterized in that, It includes a cylindrical outer shell, a first baffle is provided at one end of the outer shell, and a fuel pipe passes through the center of the first baffle; an annular air equalizer is provided inside the first baffle, the inner ring diameter of the air equalizer is larger than that of the fuel pipe, and air equalization holes are evenly provided on the inner ring wall of the air equalizer. An exhaust pipe is installed inside the fuel pipe. Inside the outer shell, the exhaust pipe extends out of the fuel pipe. The end of the fuel pipe is sealed and welded to the exhaust pipe. A premixed air pipe is installed outside the fuel pipe. One end of the premixed air pipe is flush with the end of the fuel pipe and is fixedly connected to the cooling cylinder. The other end is kept at a set distance from the air equalizer. A second baffle is installed at the end of the cooling cylinder away from the fuel pipe. A flue gas cooling annular gap is left between the second baffle and the cooling cylinder.

2. The dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, The end of the exhaust pipe that extends out of the fuel pipe is a distribution section, which is located inside the cooling cylinder. The distribution section is provided with multiple axial discharge holes and radial discharge holes.

3. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 2, characterized in that, The plurality of axial discharge holes are disposed on the bottom surface of the end of the distribution section away from the fuel pipe, and are distributed in an array around the center of the bottom surface; the plurality of radial discharge holes are uniformly disposed in the circumferential direction of the distribution section.

4. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, The first baffle has a through hole at its center, the diameter of which is the same as the diameter of the outer wall of the fuel pipe. The fuel pipe is welded and fixed to the through hole at the center of the first baffle.

5. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, The outer ring of the air equalizer is fixedly connected to the outer shell, and the air equalizer is fixedly connected to the air intake pipe, which is fixedly mounted on the outer shell.

6. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, Near the end where the premixed air pipe connects to the cooling cylinder, multiple swirl vanes are evenly arranged between the premixed air pipe and the fuel pipe.

7. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, The premixed air pipe has a premixed air channel inside, and a cooling air channel is formed between the outer wall of the premixed air pipe and the outer shell.

8. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, Inside the premixed air pipe, on the side of the swirl vane away from the cooling cylinder, multiple fuel holes are uniformly opened circumferentially on the wall of the fuel pipe.

9. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 1, characterized in that, The second baffle is welded and fixedly connected to the outer shell. The second baffle is a hollow ring with an inner ring diameter equal to the diameter of the cooling cylinder. An ignition channel is fixedly connected to the middle section of the cooling cylinder, and the ignition channel is fixedly installed on the outer shell.

10. A dual-fuel swirl burner for achieving uniform air intake and stable combustion as described in claim 9, characterized in that, Between the ignition channel and the second baffle, a plurality of flue gas cooling holes are uniformly arranged in the circumferential direction on the wall of the cooling cylinder; a plurality of flame cooling holes are uniformly arranged in the circumferential direction on the bottom surface of the end of the cooling cylinder connected to the premixed air pipe.

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