Flame burner used in solid oxide fuel cell (SOFC) system

Abstract

The invention relates to a flame burner used in a solid oxide fuel cell (SOFC) system. Comprising a first pipe fitting and a second pipe fitting, the first pipe fitting is arranged at an opening in the upper end of the second pipe fitting in a sleeving mode, a combustion chamber is arranged in the first pipe fitting, a rotational flow plate connected to the opening in the upper end of the second pipe fitting is arranged in the second pipe fitting, and an oxidizing agent hole communicated with cathode tail gas of a combustion improver and a fuel hole communicated with anode tail gas of a combustible are formed in the rotational flow plate. The oxidant hole and the fuel hole are respectively communicated with the combustion chamber, the oxidant hole comprises a side wall rotational flow hole and a plane groove type rotational flow hole, the rotational flow directions of the side wall rotational flow hole and the plane groove type rotational flow hole are opposite, and an ignition needle extending into the combustion chamber is arranged on the rotational flow plate. Through the side wall rotational flow holes and the plane groove type rotational flow holes, the retention time of fuel in the combustion chamber is prolonged, direct contact between a high-temperature area for combustion and the wall face of the combustion chamber is hindered, the side wall rotational flow holes adopt a large-angle internal rotation mode to avoid fuel dispersion, and the equivalence ratio of a main combustion area is controlled to be about 1 as much as possible through area distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of solid oxide combustion cells, and in particular relates to a flame burner used in a SOFC system. Background Art

[0002] Solid oxide fuel cell (SOFC) is a highly efficient power generation device that converts the chemical energy of fuel (such as natural gas) directly into electrical energy through electrochemical reactions without going through the combustion process. Unlike solar power generation and wind power generation, SOFC power generation technology is not restricted by seasons, climate, geographical location, time intermittency, etc. As long as natural gas, biogas and other fuels are introduced, SOFC can directly generate electricity. On the other hand, compared with traditional power generation technology, SOFC power generation system has the advantages of wide fuel sources, high power generation efficiency, almost no NOX emissions during the power generation process, and easy CO2 capture.

[0003] At present, SOFC systems need to use tail gas treatment devices to treat anode tail gas, which can achieve energy recovery on the one hand and avoid anode tail gas polluting the environment on the other hand. At present, most systems use catalytic burners to treat anode tail gas, but catalytic combustion requires a certain activation temperature and needs to be operated in conjunction with electric heaters, which increases the complexity of the system. In addition, the life of catalytic burners is short, usually needing to be replaced every 2-3 years, and the cost is high. Or a very small number of systems use a start-up burner and a stabilization burner in combination, which also causes system complexity and control complexity. Since the combustible components, temperature, and flow of the anode and cathode tail gas vary greatly, and the pressure loss of the burner is required to be very low, it is extremely challenging to design a burner that can operate stably under all conditions from heating to full load operation. In addition, under full load conditions, the preheating temperature of the anode tail gas and the cathode tail gas is relatively high. Under the premise of compact burners, how to ensure that the local high temperature of combustion does not contact the metal wall is also a major technical problem. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a flame burner for use in a SOFC system. The side wall swirl holes and the plane groove swirl holes are used to increase the residence time of the fuel in the combustion chamber, thereby preventing the high-temperature combustion area from directly contacting the combustion chamber wall. The side wall swirl holes adopt a large-angle inward rotation method to avoid fuel dispersion. Through the distribution of area, the equivalence ratio of the main combustion area is controlled to be around 1 as much as possible.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A flame burner for an SOFC system comprises a first pipe fitting and a second pipe fitting, wherein the first pipe fitting is sleeved on the upper end opening of the second pipe fitting, a combustion chamber is arranged in the first pipe fitting, and a swirl plate connected to the upper end opening of the second pipe fitting is arranged in the second pipe fitting, the swirl plate is provided with an oxidant hole connected to the cathode tail gas of an oxidation-supporting agent and a fuel hole connected to the anode tail gas of a combustible material, the oxidant hole and the fuel hole are connected to the combustion chamber respectively, the oxidant hole comprises a side wall swirl hole and a plane groove type swirl hole, the swirl directions of the side wall swirl hole and the plane groove type swirl hole are opposite, and the swirl plate is provided with an ignition needle extending into the combustion chamber.

[0007] A guide tube and a lower cover plate are also provided in the second pipe fitting, and the lower cover plate is connected to the lower end opening of the second pipe fitting. The swirl plate, the lower cover plate and the second pipe fitting are combined to form a buffer chamber. The guide tube is arranged in the buffer chamber and is respectively connected to the swirl plate and the lower cover plate. The guide tube divides the buffer chamber into an anode tail gas buffer chamber and a cathode tail gas buffer chamber. A first air inlet connected to the anode tail gas buffer chamber is provided on the lower cover plate, and the first air inlet is connected to the anode tail gas of the combustible material. A second air inlet connected to the cathode tail gas buffer chamber is provided on the second pipe fitting, and the second air inlet is connected to the cathode tail gas of the combustion aid.

[0008] A swirl section, a supplementary combustion section and a main combustion section are provided on the upper end surface of the swirl plate, and the swirl section, the supplementary combustion section and the main combustion section are connected in sequence along the inner wall of the combustion chamber toward the central axis and form a Z-shaped structure; the swirl section is provided with a plurality of plane groove-type swirl holes distributed in a circular array, the supplementary combustion section is provided with a plurality of side wall swirl holes distributed in a circular array, the main combustion section is provided with a plurality of fuel holes, and the end of the ignition needle is arranged on the main combustion section; the aperture diameter of the fuel hole is 1 to 3 mm, and the distance between the plurality of fuel holes is 1.5 to 2.5 times of the aperture diameter; the angle between the swirl section and the central axis is 70 to 85°, the angle between the supplementary combustion section and the central axis is 30 to 60°, and the area of ​​the side wall swirl hole is 1 / 10 to 1 / 30 of the area of ​​the plane groove-type swirl hole.

[0009] Furthermore, a turbulence plate is provided in the second pipe fitting, and the turbulence plate is in an annular structure. The turbulence plate is horizontally placed in the cathode tail gas buffer chamber, and turbulence holes are provided on the turbulence plate; the turbulence holes include a proximal hole and a distal hole, the proximal hole is close to the second air inlet, and the distal hole is far away from the second air inlet, and the aperture of the proximal hole is smaller than the aperture of the distal hole.

[0010] Compared with the prior art, the beneficial effects of the present invention are: (1) the setting of the side wall swirl holes and the plane groove swirl holes can increase the residence time of the fuel in the combustion chamber, making the combustion more stable; (2) the side wall swirl holes and the plane groove swirl holes prevent the high temperature area of ​​the combustion from directly contacting the combustion chamber wall, so that the material temperature of the combustion chamber wall is lower, avoiding the selection of high temperature materials, and reducing the manufacturing cost of the burner; (3) the side wall swirl holes adopt a large-angle inward rotation method to avoid the dispersion of the fuel, which has a very good effect on the stable combustion of low calorific value fuels; (4) through the distribution of area, 90% to 97% of the cathode exhaust gas flows out through the plane groove swirl holes, mainly as secondary air for supplementary combustion and reducing the combustion temperature, and the remaining cathode exhaust gas flows out through the side wall swirl holes, so that the equivalence ratio of the main combustion area is controlled to about 1 as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 A bottom-up stereogram of the present invention;

[0013] Figure 2 It is a top exploded schematic diagram of the present invention;

[0014] Figure 3 For the present invention Figure 2 A local enlarged view of point A;

[0015] Figure 4 A top view of the present invention;

[0016] Figure 5 For the present invention Figure 4 BB cross-sectional view.

[0017] Among them: 1. first pipe fitting; 11. combustion chamber; 2. second pipe fitting; 21. swirl plate; 211. oxidant hole; 2111. side wall swirl hole; 2112. plane groove swirl hole; 212. fuel hole; 213. ignition needle; 214. swirl section; 215. supplementary combustion section; 216. main combustion section; 22. guide tube; 23. lower cover plate; 231. first air inlet; 24. buffer chamber; 241. anode tail gas buffer cavity; 242. cathode tail gas buffer cavity; 25. second air inlet; 26. turbulence plate; 261. turbulence hole; 2611. proximal hole; 2612. distal hole. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0019] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings:

[0020] like Figure 1-5 As shown, a flame burner for a SOFC system comprises a first pipe fitting 1 and a second pipe fitting 2, wherein the first pipe fitting 1 is sleeved on the upper end opening of the second pipe fitting 2, a combustion chamber 11 is arranged in the first pipe fitting 1, and a swirl plate 21 connected to the upper end opening of the second pipe fitting 2 is arranged in the second pipe fitting 2, the swirl plate 21 is provided with an oxidant hole 211 connected to the cathode tail gas of the combustion aid and a fuel hole 212 connected to the anode tail gas of the combustible, the oxidant hole 211 and the fuel hole 212 are respectively connected to the combustion chamber 11, the oxidant hole 211 comprises a side wall swirl hole 2111 and a plane groove type swirl hole 2112, the swirl directions of the side wall swirl hole 2111 and the plane groove type swirl hole 2112 are opposite, and the swirl plate 21 is provided with an ignition needle 213 extending into the combustion chamber 11.

[0021] A guide tube 22 and a lower cover plate 23 are also provided in the second pipe fitting 2. The lower cover plate 23 is connected to the lower end opening of the second pipe fitting 2. The swirl plate 21, the lower cover plate 23 and the second pipe fitting 2 are combined to form a buffer chamber 24. The guide tube 22 is arranged in the buffer chamber 24 and is respectively connected to the swirl plate 21 and the lower cover plate 23. The guide tube 22 divides the buffer chamber 24 into an anode tail gas buffer chamber 241 and a cathode tail gas buffer chamber 242. A first air inlet 231 connected to the anode tail gas buffer chamber 241 is provided on the lower cover plate 23. The first air inlet 231 is connected to the anode tail gas of the combustible material. A second air inlet 25 connected to the cathode tail gas buffer chamber 242 is provided on the second pipe fitting 2. The second air inlet 25 is connected to the cathode tail gas of the combustion aid.

[0022] The upper end surface of the swirl plate 21 is provided with a swirl section 214, a supplementary combustion section 215 and a main combustion section 216, and the swirl section 214, the supplementary combustion section 215 and the main combustion section 216 are sequentially connected along the inner wall of the combustion chamber 11 toward the central axis and form a Z-shaped structure; the swirl section 214 is provided with a plurality of planar groove-shaped swirl holes 2112 distributed in a circumferential array, the supplementary combustion section 215 is provided with a plurality of side wall swirl holes 2111 distributed in a circumferential array, and the main combustion section 216 is provided with a plurality of planar groove-shaped swirl holes 2112 distributed in a circumferential array. There are a plurality of fuel holes 212, and the end of the ignition needle 213 is arranged on the main combustion section 216; the aperture of the fuel hole 212 is 1 to 3 mm, and the distance between the plurality of fuel holes 212 is 1.5 to 2.5 times of the aperture; the angle between the swirl section 214 and the central axis is 70 to 85°, the angle between the supplementary combustion section 215 and the central axis is 30 to 60°, and the area of ​​the side wall swirl hole 2111 is 1 / 10 to 1 / 30 of the area of ​​the plane groove type swirl hole 2112.

[0023] Furthermore, a turbulence plate 26 is also provided in the second pipe 2. The turbulence plate 26 is annular in structure. The turbulence plate 26 is horizontally placed in the cathode exhaust buffer chamber 242. The turbulence plate 26 is provided with turbulence holes 261; the turbulence holes 261 include a proximal hole 2611 and a distal hole 2612. The proximal hole 2611 is close to the second air inlet 25, and the distal hole 2612 is far away from the second air inlet 25. The aperture of the proximal hole 2611 is smaller than the aperture of the distal hole 2612.

[0024] Description of the working method of the present invention:

[0025] The flame burner used in the SOFC system adopts this structure, and the buffer chamber 24 enclosed by the swirl plate 21, the lower cover plate 23 and the second pipe 2 is divided into an anode tail gas buffer chamber 241 and a cathode tail gas buffer chamber 242 by the arrangement of the guide tube 22. The anode tail gas and the cathode tail gas are introduced through the connection of the first air inlet 231 and the second air inlet 25 respectively. The turbulence plate 26 arranged in the cathode tail gas buffer chamber 242 has a proximal hole 2611 close to the second air inlet 25, and a distal hole 2612 far away from the second air inlet 25. The aperture of the proximal hole 2611 is smaller than the aperture of the distal hole 2612. Therefore, when the cathode tail gas is introduced, the gas balance in the cathode tail gas buffer chamber 242 can be effectively balanced, so that the flow rate of the cathode tail gas is more stable when entering the oxidant hole 211.

[0026] The diameter of the fuel hole 212 is 2mm, and the distance between the fuel holes 212 is twice the diameter, that is, when it is 4mm, the combustion effect is the best. For the fuel hole 212, if the diameter of the fuel hole 212 is too small, the fuel outlet flow rate will be large, resulting in excessive pressure loss of the burner, and there will be a risk of clogging. Therefore, the diameter of the fuel hole 212 is 1mm, which is the lower limit of the effect it can achieve; if the central aperture is too large, it will cause the fuel to diffuse slowly, resulting in incomplete combustion and high CO emissions. Therefore, when the diameter of the fuel hole 212 is 3mm, it is the upper limit of the effect it can achieve; for the spacing between holes, if the spacing is large, it is more difficult to transfer fire, which may cause some holes to fail to burn normally. Therefore, normal combustion can only be achieved within 2.5 times the aperture; if the hole spacing is small, the fuel will be more concentrated and more difficult to burn completely. Therefore, the effect of complete combustion can be basically achieved when it is more than 1.5 times the aperture.

[0027] For the several planar slot-shaped swirl holes 2112 distributed in a circular array on the swirl section 214, the best angle is 75° between the swirl section 214 and the central axis. If the angle is too large, the residence time of the cathode exhaust gas from the planar slot-shaped swirl holes 2112 in the burner increases, and the wall temperature cannot be effectively reduced. Therefore, the angle cannot exceed 85°; if the angle is too small, the smoke swirl intensity is reduced, and a good supplementary combustion and swirl effect cannot be achieved. Therefore, the angle cannot be lower than 70°.

[0028] The side wall swirl holes 2111 distributed in a circular array on the supplementary combustion section 215 work best when the angle between the supplementary combustion section 215 and the central axis is 45°. If the angle is too small, less than 30°, an effective vortex cannot be formed, resulting in a reduced combustion mixing effect and possible incomplete combustion. If the angle is too large, more than 60°, counter-wind will be formed, which will increase the flow resistance of the burner and increase the pressure loss of the burner.

[0029] The best combustion effect is achieved when the area of ​​the side wall swirl hole 2111 is 1 / 20 of the area of ​​the plane groove type oxidant hole 211. If this parameter is larger and exceeds 1 / 10, the burner wall temperature will be too high, and the life of the burner will be drastically shortened under long-term operation; if this parameter is lower and lower than 1 / 30, the primary air of the burner will be lower, the main combustion zone cannot be effectively formed, and the combustion efficiency will be reduced.

[0030] Take a 10kW SOFC system as an example. During the startup phase, the fuel flow rate is 3-5SLM, the air flow rate is 800SLM, and 10% of the cathode tail gas enters the combustion chamber 11 through the side wall swirl hole 2111. During startup, since most of the fuel is natural gas, 80SLM of air is used as primary air to participate in the combustion in the main combustion zone. At this time, the equivalence ratio is about 1. If all 800SLM of air participate in the combustion or perform full premixed combustion, stable ignition may not be achieved at such a low fuel flow rate. Therefore, the area distribution of the side wall swirl hole 2111 and the plane groove swirl hole 2112 is the key to the successful ignition of the burner. As the ignition is completed, the system temperature slowly rises, and the burner outlet temperature gradually increases from 100°C. When the water flow condition is reached, water vapor is introduced. The introduction of water vapor reduces the calorific value of the fuel. Since the anode tail gas flows out from the fuel hole 212, the side wall swirl hole 2111 has a heat preservation effect during the combustion process, so that the flame can stably swirl in the center, and the combustion can continue to be stably maintained. At this time, the outlet temperature of the burner is about 400°C. Then the fuel of the burner is gradually increased to continue to heat up the system. Finally, the stack reaches the rated fuel utilization rate. At this time, most of the anode tail gas is H2O and CO2, and the concentration of combustible H2 and CO is reduced to about 10%. The calorific value of the anode tail gas is reduced to 1500kJ / kg, which is much lower than low calorific value conventional fuels such as coalbed methane and synthesis gas. By adopting the side wall swirl holes 2111 and the plane groove swirl holes 2112, the residence time of H2 and CO in the combustion chamber 11 is greatly enhanced, and the residence time can reach more than 20ms. Since the anode exhaust gas and the cathode exhaust gas have very high preheating temperatures, and the swirl can further play a role in heat preservation, the burner can still burn stably under rated conditions, and the emissions of combustion exhaust CO and H2 can be reduced to ppm level. The maximum temperature of the combustion wall is lower than 900°C, and the flue gas temperature is maintained at around 850°C.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame burner for use in a SOFC system, characterized in that: It includes a first pipe fitting and a second pipe fitting, the first pipe fitting is sleeved on the upper end opening of the second pipe fitting, a combustion chamber is arranged in the first pipe fitting, a swirl plate connected to the upper end opening of the second pipe fitting is arranged in the second pipe fitting, the swirl plate is provided with an oxidant hole connected to the cathode tail gas of the combustion aid and a fuel hole connected to the anode tail gas of the combustible material, the oxidant hole and the fuel hole are connected to the combustion chamber respectively, the oxidant hole includes a side wall swirl hole and a plane groove type swirl hole, the swirl directions of the side wall swirl hole and the plane groove type swirl hole are opposite, and the swirl plate is provided with an ignition needle extending into the combustion chamber.

2. The flame burner for use in a SOFC system according to claim 1, characterized in that: A guide tube and a lower cover plate are also provided in the second pipe fitting, and the lower cover plate is connected to the lower end opening of the second pipe fitting. The swirl plate, the lower cover plate and the second pipe fitting are combined to form a buffer chamber. The guide tube is arranged in the buffer chamber and is respectively connected to the swirl plate and the lower cover plate. The guide tube divides the buffer chamber into an anode tail gas buffer chamber and a cathode tail gas buffer chamber. A first air inlet connected to the anode tail gas buffer chamber is provided on the lower cover plate, and the first air inlet is connected to the anode tail gas of the combustible material. A second air inlet connected to the cathode tail gas buffer chamber is provided on the second pipe fitting, and the second air inlet is connected to the cathode tail gas of the combustion aid.

3. The flame burner for use in a SOFC system according to claim 2, characterized in that: The upper surface of the swirl plate is provided with a swirl section, a supplementary combustion section and a main combustion section, and the swirl section, the supplementary combustion section and the main combustion section are connected in sequence along the inner wall of the combustion chamber toward the central axis and form a Z-shaped structure.

4. The flame burner for use in a SOFC system according to claim 3, characterized in that: The swirl section is provided with a plurality of planar groove-shaped swirl holes distributed in a circumferential array, the supplementary combustion section is provided with a plurality of side wall swirl holes distributed in a circumferential array, the main combustion section is provided with a plurality of fuel holes, and the end of the ignition needle is arranged on the main combustion section.

5. The flame burner for use in a SOFC system according to claim 4, characterized in that: The diameter of the fuel hole is 1 to 3 mm, and the distance between the plurality of fuel holes is 1.5 to 2.5 times of the diameter.

6. The flame burner for use in a SOFC system according to claim 5, characterized in that: The angle between the swirl section and the central axis is 70-85°, the angle between the supplementary combustion section and the central axis is 30-60°, and the area of ​​the side wall swirl hole is 1 / 10-1 / 30 of the area of ​​the plane groove type swirl hole.

7. The flame burner for use in a SOFC system according to claim 2, characterized in that: The second pipe is further provided with a turbulence plate, which is an annular structure and is horizontally placed in the cathode tail gas buffer chamber. The turbulence plate is provided with turbulence holes.

8. The flame burner for use in a SOFC system according to claim 7, characterized in that: The turbulence hole comprises a proximal hole and a distal hole, the proximal hole is close to the second air inlet, the distal hole is far away from the second air inlet, and the aperture of the proximal hole is smaller than the aperture of the distal hole.

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