A flame burner for use in SOFC systems

Abstract

This invention relates to a flame burner for use in an SOFC system. It includes a first pipe and a second pipe, with the first pipe fitted over the upper opening of the second pipe. The first pipe contains a combustion chamber, and the second pipe contains a swirl plate connected to its upper opening. The swirl plate has an oxidizer hole communicating with the cathode exhaust gas of the combustion-supporting agent and a fuel hole communicating with the anode exhaust gas of the combustible material. The oxidizer hole and fuel hole are respectively connected to the combustion chamber. The oxidizer hole includes sidewall swirl holes and planar groove-shaped swirl holes, with opposite swirl directions. An ignition needle extending into the combustion chamber is provided on the swirl plate. This invention increases the residence time of fuel in the combustion chamber through the sidewall swirl holes and planar groove-shaped swirl holes, preventing direct contact between the high-temperature combustion zone and the combustion chamber wall. The sidewall swirl holes employ a large-angle inward swirl to avoid fuel dispersion, and the area distribution controls the equivalence ratio of the main combustion zone to approximately 1.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide combustion battery technology, specifically relating to a flame burner for use in SOFC systems. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are highly efficient power generation devices that directly convert the chemical energy of fuels (such as natural gas) into electrical energy through electrochemical reactions without a combustion process. Unlike solar and wind power generation, SOFC technology is not limited by seasons, climate, geographical location, or time intermittency; as long as fuels such as natural gas or biogas are supplied, SOFCs can generate electricity directly. Furthermore, compared to traditional power generation technologies, SOFC systems offer advantages such as a wide range of fuel sources, high power generation efficiency, virtually no NOx emissions during power generation, and easy CO2 capture.

[0003] Currently, SOFC systems require exhaust gas treatment devices to treat the anode exhaust gas. This enables energy recovery and prevents environmental pollution from the anode exhaust gas. Most systems currently use catalytic burners to treat the anode exhaust gas; however, catalytic combustion requires a certain activation temperature and necessitates operation in conjunction with an electric heater, increasing system complexity. Furthermore, catalytic burners have a short lifespan, typically requiring replacement every 2-3 years, and are costly. A very small number of systems use a combination of start-up and stabilizing burners, which also contributes to system and control complexity. Because the combustible composition, temperature, and flow rate of the anode and cathode exhaust gases vary greatly, and the burner requires very low pressure loss, designing a burner that can operate stably under all conditions from heating to full load presents a significant challenge. Moreover, under full load, the preheating temperatures of the anode and cathode exhaust gases are high. Ensuring that the localized high temperatures of combustion do not contact the metal wall within a compact burner design is another major technical challenge. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a flame burner for SOFC systems. By using sidewall swirl holes and planar groove-shaped swirl holes, the residence time of fuel in the combustion chamber is increased, which prevents the high-temperature combustion zone from directly contacting the combustion chamber wall. The sidewall swirl holes adopt a large-angle inward swirling method to avoid fuel dispersion. Through the distribution of area, the equivalence ratio of the main combustion zone is controlled as close to 1 as possible.

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

[0006] A flame burner for an SOFC system includes a first tube and a second tube. The first tube is fitted onto the upper opening of the second tube. A combustion chamber is provided inside the first tube. A swirl plate connected to the upper opening of the second tube is provided inside the second tube. The swirl plate has an oxidant hole communicating with the cathode exhaust gas of the combustion aid and a fuel hole communicating with the anode exhaust gas of the combustible material. The oxidant hole and the fuel hole are respectively connected to the combustion chamber. The oxidant hole includes a sidewall swirl hole and a planar groove swirl hole. The swirl directions of the sidewall swirl hole and the planar groove swirl hole are opposite. An ignition needle extending into the combustion chamber is provided on the swirl plate.

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

[0008] The upper surface of the swirl plate is provided with a swirl section, a combustion section, and a main combustion section. The swirl section, combustion section, and main combustion section are connected sequentially along the side wall of the combustion chamber towards the central axis in a Z-shaped structure. The swirl section is provided with a plurality of planar groove-shaped swirl holes arranged in a circumferential array. The combustion section is provided with a plurality of sidewall swirl holes arranged in a circumferential array. The main combustion section is provided with a plurality of fuel holes. The end of the ignition needle is located on the main combustion section. The diameter of the fuel holes is 1 to 3 mm, and the distance between a plurality of fuel holes is 1.5 to 2.5 times the diameter. The angle between the swirl section and the central axis is 70 to 85°, the angle between the combustion section and the central axis is 30 to 60°, and the area of ​​the sidewall swirl holes is 1 / 10 to 1 / 30 of the area of ​​the planar groove-shaped swirl holes.

[0009] Furthermore, the second pipe fitting is also provided with a turbulence plate, which has an annular structure and is horizontally placed in the cathode exhaust gas buffer chamber. The turbulence plate is provided with turbulence holes. 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 from the second air inlet. The diameter of the proximal hole is smaller than the diameter of the distal hole.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The setting of sidewall swirl holes and planar groove swirl holes can increase the residence time of fuel in the combustion chamber, making the combustion more stable; (2) The sidewall swirl holes and planar groove swirl holes prevent the high-temperature area of ​​combustion from directly contacting the combustion chamber wall, making the material temperature of the combustion chamber wall lower, avoiding the selection of high-temperature materials, and reducing the manufacturing cost of the burner; (3) The sidewall swirl holes adopt a large-angle inward swirl method, which can avoid the dispersion of fuel and 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 planar 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 sidewall swirl holes, so that the equivalence ratio of the main combustion area is controlled as close to 1 as possible. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a bottom-view perspective view of the present invention;

[0013] Figure 2 This is a top-view explosion diagram of the present invention;

[0014] Figure 3 For the present invention Figure 2 A magnified view of part A;

[0015] Figure 4 This is a top view of the present invention;

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

[0017] Wherein: 1. First fitting; 11. Combustion chamber; 2. Second fitting; 21. Swirl plate; 211. Oxidizer hole; 2111. Side wall swirl hole; 2112. Planar groove-shaped swirl hole; 212. Fuel hole; 213. Ignition needle; 214. Swirl section; 215. Afterburning section; 216. Main combustion section; 22. Guide tube; 23. Lower cover plate; 231. First air inlet; 24. Buffer chamber; 241. Anode exhaust gas buffer chamber; 242. Cathode exhaust gas buffer chamber; 25. Second air inlet; 26. Turbulence plate; 261. Turbulence hole; 2611. Proximal hole; 2612. Distal hole. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] The specific embodiments of the present invention will now be described with reference to the accompanying drawings:

[0020] like Figure 1-5 As shown, a flame burner for an SOFC system includes a first tube 1 and a second tube 2. The first tube 1 is fitted onto the upper opening of the second tube 2. A combustion chamber 11 is provided inside the first tube 1. A swirl plate 21 connected to the upper opening of the second tube 2 is provided inside the second tube 2. The swirl plate 21 has an oxidant hole 211 communicating with the cathode exhaust gas of the combustion aid and a fuel hole 212 communicating with the anode exhaust gas of the combustible material. The oxidant hole 211 and the fuel hole 212 are respectively connected to the combustion chamber 11. The oxidant hole 211 includes a sidewall swirl hole 2111 and a planar groove swirl hole 2112. The swirl directions of the sidewall swirl hole 2111 and the planar groove swirl hole 2112 are opposite. An ignition needle 213 extending into the combustion chamber 11 is provided on the swirl plate 21.

[0021] The second pipe fitting 2 is also provided with a guide tube 22 and a lower cover plate 23. The lower cover plate 23 is connected to the lower opening of the second pipe fitting 2. The swirl plate 21, the lower cover plate 23 and the second pipe fitting 2 enclose a buffer chamber 24. The guide tube 22 is disposed in the buffer chamber 24 and is connected to the swirl plate 21 and the lower cover plate 23 respectively. 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. The lower cover plate 23 is provided with a first air inlet 231 that communicates with the anode tail gas of the combustible material. The second pipe fitting 2 is provided with a second air inlet 25 that communicates with the cathode tail gas buffer chamber 242. The second air inlet 25 communicates with the cathode tail gas of the combustion aid.

[0022] The upper surface of the swirl plate 21 is provided with a swirl section 214, a secondary combustion section 215, and a main combustion section 216. The swirl section 214, secondary combustion section 215, and main combustion section 216 are sequentially connected along the inner sidewall of the combustion chamber 11 towards 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 arranged in a circumferential array. The secondary combustion section 215 is provided with a plurality of sidewall swirl holes 2111 arranged in a circumferential array. The main combustion section 216 is provided with... A plurality of fuel holes 212 are provided, and the end of the ignition needle 213 is disposed on the main combustion section 216; the diameter of the fuel holes 212 is 1 to 3 mm, and the distance between the plurality of fuel holes 212 is 1.5 to 2.5 times the diameter; the swirl section 214 has an angle of 70 to 85° with the central axis, the afterburning section 215 has an angle of 30 to 60° with the central axis, and the area of ​​the sidewall swirl hole 2111 is 1 / 10 to 1 / 30 of the area of ​​the planar groove swirl hole 2112.

[0023] Furthermore, the second pipe fitting 2 is also provided with a turbulence plate 26, which has an annular structure and is horizontally placed in the cathode exhaust gas 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 from the second air inlet 25. The diameter of the proximal hole 2611 is smaller than the diameter of the distal hole 2612.

[0024] Description of the working principle of this invention:

[0025] The flame burner in the SOFC system with this structure has a buffer chamber 24 enclosed by the swirl plate 21, the lower cover plate 23, and the second pipe 2. The buffer chamber 24 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 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 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 diameter of the proximal hole 2611 is smaller than that 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 when entering the oxidant hole 211 is more stable.

[0026] The optimal combustion effect is achieved when the fuel orifice 212 has a diameter of 2mm and the distance between the fuel orifices 212 is twice the orifice diameter, i.e., 4mm. If the fuel orifice 212 diameter is too small, the fuel outlet velocity will be too high, resulting in excessive burner pressure loss and a risk of blockage. Therefore, a fuel orifice diameter of 1mm is the lower limit for achieving the desired effect. If the central orifice diameter is too large, fuel diffusion will be slow, leading to incomplete combustion and higher CO emissions. Therefore, a fuel orifice diameter of 3mm is the upper limit for achieving the desired effect. Regarding the spacing between the orifices, a large spacing makes ignition difficult, potentially causing some orifices to fail to burn properly. Therefore, a spacing within 2.5 times the orifice diameter is required for normal combustion. If the orifice spacing is too small, the fuel will be too concentrated, making complete combustion difficult. Therefore, a spacing of more than 1.5 times the orifice diameter is required to achieve essentially complete combustion.

[0027] For the several planar slotted swirl holes 2112 distributed in a circular array on the swirl section 214, the optimal angle between the swirl section 214 and the central axis is 75°. If the angle is too large, the residence time of the cathode exhaust gas of the planar slotted swirl holes 2112 in the burner will increase, and it will not be able to effectively reduce the temperature of the wall surface. Therefore, the angle should not exceed 85°. If the angle is too small, the intensity of flue gas swirl will decrease, and it will not be able to achieve a good combustion and swirl effect. Therefore, the angle should not be lower than 70°.

[0028] The sidewall swirl holes 2111 arranged in a circular array on the afterburning section 215 are most effective when the angle between the afterburning section 215 and the central axis is 45°. If the angle is too small, below 30°, an effective vortex cannot be formed, resulting in a reduced combustion mixing effect and possible incomplete combustion. If the angle is too large, above 60°, a counter-current airflow will be formed, which will increase the flow resistance of the burner and lead to an increase in the pressure loss of the burner.

[0029] The combustion effect is optimal when the area of ​​the sidewall swirl holes 2111 is 1 / 20 of the area of ​​the planar groove-type oxidant holes 211. If this parameter is larger than 1 / 10, the burner wall temperature will be too high, which will lead to a sharp reduction in the burner's lifespan under long-term operation. If this parameter is lower than 1 / 30, the primary air of the burner will be too low, the main combustion zone cannot be effectively formed, and the combustion efficiency will be reduced.

[0030] Taking a 10kW SOFC system as an example, during the start-up phase, the fuel flow rate is 3-5 SLM, the air flow rate is 800 SLM, and 10% of the cathode exhaust gas enters the combustion chamber 11 through the sidewall swirl orifice 2111. During start-up, since most of the fuel is natural gas, the 80 SLM of air participates in combustion as primary air in the main combustion zone, resulting in an equivalence ratio of approximately 1. If all 800 SLM of air were to participate in combustion or undergo fully premixed combustion, stable ignition might not be possible at such a low fuel flow rate. Therefore, the area distribution of the sidewall swirl orifice 2111 and the planar groove-shaped swirl orifice 2112 is crucial for successful burner ignition. As ignition completes, the system temperature gradually increases, with the burner outlet temperature gradually increasing from 100℃. When the water supply conditions are met, steam is introduced. The introduction of steam reduces the calorific value of the fuel. Since the anode exhaust gas flows out from the fuel orifice 212, the swirl holes 2111 on the side wall have a heat-insulating effect during combustion, allowing the flame to swirl stably in the center, and combustion can continue to be maintained stably. At this time, the outlet temperature of the burner is about 400℃. Then, the fuel in the burner is gradually increased to continue to heat the system. Finally, the fuel stack reaches the rated fuel utilization rate. At this time, most of the anode exhaust gas is H2O and CO2, and the concentration of combustibles H2 and CO is reduced to about 10%. The calorific value of the anode exhaust gas is reduced to 1500kJ / kg, which is far lower than that of conventional fuels with low calorific value such as coalbed methane and syngas. By employing sidewall swirl holes 2111 and planar groove-shaped swirl holes 2112, the residence time of H2 and CO in the combustion chamber 11 is greatly enhanced, reaching more than 20ms. Due to the very high preheating temperature of the anode and cathode exhaust gases, and the further heat preservation effect of the swirl, the burner can still burn stably under rated operating conditions. The emissions of CO and H2 in the combustion exhaust gas can be reduced to the ppm level, the maximum wall temperature of the combustion chamber is below 900℃, and the flue gas temperature is maintained at around 850℃.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame burner for use in an SOFC system, characterized in that: The system includes a first pipe fitting and a second pipe fitting. The first pipe fitting is fitted onto the upper opening of the second pipe fitting. The first pipe fitting contains a combustion chamber. The second pipe fitting contains a swirl plate connected to the upper opening of the second pipe fitting. The swirl plate has an oxidizer hole communicating with the cathode exhaust gas of the combustion-supporting agent and a fuel hole communicating with the anode exhaust gas of the combustible material. The oxidizer hole and fuel hole are respectively connected to the combustion chamber. The oxidizer hole includes sidewall swirl holes and planar groove-shaped swirl holes, with opposite swirl directions. The swirl plate has an ignition needle extending into the combustion chamber. The second pipe fitting also contains a guide tube and a lower cover plate. The lower cover plate is connected to the lower opening of the second pipe fitting. The swirl plate, lower cover plate, and second pipe fitting together form a buffer chamber. The guide tube is disposed within the buffer chamber and connected to both the swirl plate and the lower cover plate. The guide tube divides the buffer chamber into an anode exhaust gas buffer chamber and a cathode exhaust gas buffer chamber. The lower cover plate has a connection to the anode exhaust gas buffer chamber. The first air inlet is connected to the anode exhaust gas of the combustible material. The second pipe has a second air inlet connected to the cathode exhaust gas buffer chamber, which is also connected to the cathode exhaust gas of the combustion aid. The upper surface of the swirl plate has a swirl section, a secondary combustion section, and a main combustion section, which are sequentially connected along the side wall of the combustion chamber towards the central axis in a Z-shaped structure. The swirl section has several planar groove-shaped swirl holes arranged in a circular array. The secondary combustion section... The upper part is provided with a number of sidewall swirl holes arranged in a circumferential array, and the main combustion section is provided with a number of fuel holes. The end of the ignition needle is set on the main combustion section. The second pipe is also provided with a turbulence plate, which has a ring structure and is horizontally placed in the cathode exhaust gas buffer chamber. The turbulence plate is provided with turbulence holes. The turbulence holes include proximal holes and distal holes. The proximal holes are close to the second air inlet, and the distal holes are far from the second air inlet. The diameter of the proximal holes is smaller than that of the distal holes.

2. The flame burner for an SOFC system according to claim 1, characterized in that: The diameter of the fuel orifice is 1 to 3 mm, and the distance between several fuel orifices is 1.5 to 2.5 times the orifice diameter.

3. The flame burner for an SOFC system according to claim 2, characterized in that: The angle between the swirl section and the central axis is 70-85°, the angle between the combustion section and the central axis is 30-60°, and the area of ​​the sidewall swirl hole is 1 / 10 to 1 / 30 of the area of ​​the planar groove-type swirl hole.

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