Low-flow hydrogen burner suitable for solid oxide fuel cell

Abstract

The invention discloses a low-flow hydrogen burner suitable for a solid oxide fuel cell, which comprises a combustion chamber provided with a fan inlet, and the combustion chamber is positioned at the axis and is symmetrically distributed; a primary air pipe, a primary air annular channel, a hydrogen combustion pipe, an annular plate, a hydrogen pore plate, a secondary air annular channel, a secondary air inlet pipe, an air distribution outer annular channel, a round pipe and a blocking plate are arranged in the combustion chamber; the primary air annular channel, the secondary air annular channel and the air distribution outer annular channel are sequentially arranged outwards from the center of a shaft and are provided with a plurality of air nozzles, and combustion is achieved after primary air and secondary air are distributed. A plurality of hydrogen nozzles are formed in the hydrogen pore plate, and fuel is jetted to form jet flow; the nozzle is divided into an inner ring, a middle ring and an outer ring, the diameter of the middle ring is the largest, and the diameters of the inner ring and the outer ring are the same and minimum; air and low-flow hydrogen can be rapidly mixed, combustion is sufficient, and backfire can be effectively prevented. Meanwhile, through reasonable channel air volume distribution, the problem that the air excess coefficient is too large is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal energy engineering and relates to a burner, in particular to a low-flow hydrogen burner suitable for a solid oxide fuel cell. Background Art

[0002] Solid oxide fuel cell SOFC is the third generation fuel cell, with high efficiency, no pollution, low noise and other remarkable features, and has received widespread attention. Although SOFC has a wide range of fuel applicability, suitable for methane, methanol, pure hydrogen and other fuels, the use of carbon-containing fuels will inevitably generate carbon deposition on the electrodes, affecting the battery life. On the contrary, using hydrogen as fuel will not cause carbon deposition reaction in the high temperature operating environment of SOFC, which can greatly extend its service life.

[0003] The high-temperature operating environment of SOFC inevitably requires equipment to provide heat. When SOFC is started, the inlet gas is cold and needs to be heated to the set temperature; when SOFC is running stably, there is unconsumed fuel in the outlet gas, so adding a burner device at the back end of the SOFC system can not only use the exhaust gas at the burner outlet to continuously reheat the inlet gas when SOFC is started, but also make the system run efficiently under stable operating conditions, thereby improving system efficiency.

[0004] Since the operating temperature of SOFC is very high and the reaction is an exothermic process, a large excess air coefficient is required to control the temperature of the stack in order to ensure safe, stable and long-lasting operation. Currently, under stable operating conditions, the ratio of the maximum air flow to the hydrogen flow reaches 152 times, and the ratio of hydrogen to water vapor in the inlet fuel reaches 1:4, making it difficult to achieve long-term stable combustion of the burner. Summary of the invention

[0005] In order to solve the difficulties in applying the above-mentioned technology, the purpose of the present invention is to provide a low-flow hydrogen burner suitable for solid oxide fuel cells, so as to burn safely, stably and efficiently and provide high-temperature exhaust gas.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A low-flow hydrogen burner suitable for a solid oxide fuel cell comprises a combustion chamber equipped with a fan inlet 20, the combustion chamber is located at the axis and is symmetrically distributed; the combustion chamber is provided with a primary air duct 1, a primary air ring channel 2, a hydrogen combustion tube 3, a ring plate 4, a hydrogen hole plate 5, a secondary air ring channel 6, a secondary air inlet pipe 7, an air distribution outer ring channel 8, a circular tube 9 and a blocking plate 10; wherein the primary air ring channel 2, the ring plate 4, the secondary air ring channel 6 and the air distribution outer ring channel 8 are arranged outward in sequence from the axis center, and the circular tube 9 and the blocking plate 10 wrap the inside of the combustion chamber; the primary air duct 1 is connected to the primary air ring channel 2, the primary air ring channel 2 is connected to the secondary air ring channel 6 through the ring plate 4, the secondary air duct 7 is connected to the secondary air ring channel 6, and the air distribution outer ring channel 8 is connected to the circular tube 9, so as to realize the distribution of primary and secondary air and then combustion;

[0008] The hydrogen combustion tube 3 is connected to the mixed gas inlet tube 12, the hydrogen inlet tube 17, and the ring plate 4, and the end of the hydrogen combustion tube 3 along the hydrogen flow direction is connected to the hydrogen hole plate 5;

[0009] The circular tube 9 is also provided with a high-pressure ignition rod tube 18 connected to the secondary air duct 7. The high pressure generated by the high-pressure package strikes an arc through the inner wall of the secondary air duct 7 to generate electric sparks, igniting hydrogen to form a flame.

[0010] Preferably, the hydrogen orifice plate 5 is provided with a plurality of hydrogen nozzles, and the fuel is sprayed to form a jet; the nozzles are divided into three circles, namely the inner circle, the middle circle and the outer circle, with the largest aperture, and the inner circle and the outer circle having the same and smallest aperture; the large aperture of the middle circle allows more hydrogen to be ejected from the middle circle, fully mixed with the air, and produce a central flame; the small apertures of the inner and outer circles provide uniform airflow distribution, assist in providing peripheral flames, ensure the stability and uniformity of the entire flame, and achieve a better mixing effect of the overall combustion gas, more complete combustion, and reduce the risk of flashback. The large-aperture middle circle can produce a larger flame and provide the main heat source; while the small-aperture inner and outer circles can assist in distributing heat, ensuring a more uniform temperature distribution inside and outside the burner.

[0011] Preferably, the number and diameter of the hydrogen nozzles on the hydrogen orifice plate 5 are determined by a specific hydrogen flow rate.

[0012] Preferably, the fan inlet 20 is arranged at the inlet end of the combustion chamber, and the incoming air is blown into the primary air ring duct 2, the secondary air ring duct 6, and the air distribution outer ring duct 8 through the fan inlet 20, and the injection direction is axial.

[0013] Preferably, the primary air ring duct 2 is provided with a plurality of air nozzles, the secondary air ring duct 6 is provided with a plurality of air nozzles, and the air distribution outer ring duct 8 is provided with a plurality of air nozzles; wherein, the primary air ring duct 2 is located at the innermost side of the axis, mainly providing the required oxygen for initial combustion, the secondary air ring duct 6 is located at the middle side of the axis, mainly providing the additional oxygen required for complete combustion, and the air distribution outer ring duct 8 is located at the outer side of the axis, mainly used for cooling the outer tube wall of the combustion chamber; after the air volume is distributed through the outer ring duct and the middle ring duct, the air flow rate of the center layer is the smallest, which is the primary air; the air flow rate of the middle ring duct is slightly larger, which is the secondary air, which supplements the amount of oxygen in the combustion process, ensures the complete combustion of the fuel, and controls the flame shape and temperature distribution; the air volume of the outer ring duct is the largest, which is used for cooling the outer wall of the tube and preventing the burner material from overheating.

[0014] Preferably, the number and diameter of the openings of the air nozzles on the primary air duct 2, the secondary air duct 6 and the air distribution outer duct 8 are determined by the specific air distribution volume.

[0015] Preferably, the mixed gas inlet pipe 12 is connected to the SOFC stack anode tail gas, and the hydrogen inlet pipe 17 is connected to low-flow high-purity hydrogen, wherein the SOFC stack anode tail gas refers to a small flow of hydrogen mixed with water vapor, and the volume proportion of hydrogen in the hydrogen and water vapor mixture is less than 25%, and high-purity hydrogen refers to 99.99% purity or above.

[0016] Preferably, the fan inlet 20 is connected to the cathode tail gas outlet of the SOFC stack.

[0017] Preferably, a flame detection port 13 and a temperature detection port 14 are provided in the circular tube 9 .

[0018] Preferably, a flame observation port 19 is provided on the burner.

[0019] Compared with the prior art, the present invention can quickly mix air and hydrogen, make combustion complete, and effectively prevent the occurrence of flashback. At the same time, through reasonable channel air volume distribution, the problem of excessive air excess coefficient is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of the present invention.

[0021] Figure 2 It is a cross-sectional view of the present invention.

[0022] Figure 3 It is a schematic diagram of the main components of the combustion chamber of the present invention.

[0023] Figure 4 It is a schematic diagram of the hydrogen nozzle of the present invention.

[0024] In the figure: 1-primary air duct, 2-primary air ring channel, 3-hydrogen combustion tube, 4-ring plate, 5-hydrogen hole plate, 6-secondary air ring channel, 7-secondary air inlet pipe, 8-air distribution outer ring channel, 9-circular tube, 10-blocking plate, 11-expansion, 12-mixed gas inlet pipe, 13-flame detection port, 14-temperature detection port, 15-smoke connection port, 16-housing, 17-hydrogen inlet pipe, 18-high-pressure ignition rod tube, 19-flame observation port, 20-fan inlet DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0026] refer to Figure 2 and Figure 3 The inlet end of the combustion chamber is provided with a fan inlet 20, which should be connected to the cathode tail gas outlet of the SOFC stack when the SOFC system is actually running. The incoming air passes through the fan inlet 20 along the axial direction through each air distribution channel into the combustion chamber.

[0027] The primary air duct 1 is connected to the primary air ring channel 2, which is provided with an air nozzle. The primary air ring channel 2 is connected to the secondary air ring channel 6 through the ring plate 4, which is provided with an air nozzle. The secondary air ring channel 6 is connected to the outer ring channel 8, which is provided with an air nozzle. The circular tube 9 and the blocking plate 10 wrap the interior of the above-mentioned combustion chamber, and a thermocouple and a flame detector are arranged in the circular tube 9. And because the air volume distribution of the outer ring channel 8 is the largest, which is not much different from the actual air volume introduced by the external fan, the error of the thermocouple measuring the air temperature is smaller. The circular tube 9 is also provided with a high-pressure ignition rod tube 18 connected to the secondary air duct 7. The high pressure generated by the high-pressure package is arced through the inner wall of the secondary air duct 7 to generate an electric spark, igniting the hydrogen to form a flame. The combustion exhaust gas is discharged in the direction of the flame and enters the next level of equipment through the flue gas connection port 15.

[0028] The air distribution channel is divided into three layers: outer ring channel, middle ring channel and center, and its inner diameter decreases successively. Among them, the primary air ring channel 2 is located at the innermost side of the axis, mainly providing the required oxygen for initial combustion, the secondary air ring channel 6 is located in the middle side of the axis, mainly providing the additional oxygen required for complete combustion, and the air distribution outer ring channel 8 is located outside the axis, mainly used to cool the outer tube wall of the combustion chamber. The number of openings of the air nozzle of the air distribution outer ring channel 8 is 166, the number of openings of the air nozzle of the secondary air ring channel 6 is 60, and the number of openings of the air nozzle of the primary air ring channel 2 is 29. After the air volume distribution of the outer ring channel and the middle ring channel, the air flow rate of the center layer is the smallest, and the wind speed reaches 3.5m / s, which is the primary air; the air flow rate of the middle ring channel is slightly larger, and the wind speed reaches 3.6m / s, which is the secondary air, which supplements the amount of oxygen in the combustion process, ensures the complete combustion of the fuel, and controls the flame shape and temperature distribution; the air volume of the outer ring channel is the largest, and the wind speed reaches 20-25m / s, which is used to cool the outer wall of the tube and prevent the burner material from overheating.

[0029] The fuel enters the hydrogen combustion tube 3 through the hydrogen inlet pipe 17 during the startup condition and through the mixed gas inlet 12 during the stable operation condition, and enters the hydrogen orifice plate 5 axially and is ejected from the nozzle. The hydrogen outlet velocity is 10m / s. The hydrogen orifice plate 5 has several nozzles, which are divided into three circles: the inner circle, the middle circle, and the outer circle. The middle circle has the largest aperture, and the inner and outer circles have the same and smallest apertures. The inner circle has 32 holes, the middle circle has 16 holes, and the outer circle has 48 holes. The large aperture of the middle circle allows more hydrogen to be ejected from the middle circle, fully mixed with the air, and produce a central flame. The small apertures of the inner and outer circles provide uniform airflow distribution, assist in providing peripheral flames, ensure the stability and uniformity of the entire flame, and achieve better mixing of the overall combustion gas, more complete combustion, and reduce the risk of flashback. The large-aperture middle circle can produce a larger flame and provide the main heat source; while the small-aperture inner and outer circles can assist in distributing heat to ensure a more uniform temperature distribution inside and outside the burner.

[0030] The tail end of the burner of the present invention is a smoke connection outlet for providing high-temperature combustion smoke.

[0031] Therefore, the burner of the present invention adopts a multi-channel and multi-nozzle design, and solves the problem of excessive air excess coefficient through the design of the air distribution channel. The flame stable combustion under the conditions of low flow hydrogen and mixed water vapor is achieved through the design of the nozzle. When applied to the solid oxide fuel cell system, stable and safe combustion can be achieved under the continuous variable operating conditions of different fuel flow rates under the startup condition, so as to achieve the purpose of controlling the outlet flue gas temperature. It has been experimentally verified that when the air flow rate is 66m 3 / h, hydrogen flow rate is 0.5-3m 3 / h, and the inlet temperature is stable combustion under room temperature conditions. It has been experimentally verified that the air flow rate is 66m 3 / h, hydrogen flow rate is 0.7m 3 / h, water vapor flow rate is 1-2.5m 3 / h under the condition of stable combustion of the burner.

[0032] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and invention concept of the present invention within the scope disclosed by the present invention, which are within the protection scope of the present invention.

Claims

1. A low flow hydrogen burner suitable for a solid oxide fuel cell, characterized in that: The invention comprises a combustion chamber equipped with a fan inlet (20), wherein the combustion chamber is located at the axis center and is symmetrically distributed; the combustion chamber is provided with a primary air duct (1), a primary air ring channel (2), a hydrogen combustion tube (3), a ring plate (4), a hydrogen hole plate (5), a secondary air ring channel (6), a secondary air inlet pipe (7), an air distribution outer ring channel (8), a circular tube (9) and a blocking plate (10); wherein the primary air ring channel (2), the ring plate (4), the secondary air ring channel (6) and the air distribution outer ring channel (8) are arranged outward in sequence from the axis center, and the circular tube (9) and the blocking plate (10) wrap the interior of the combustion chamber; the primary air duct (1) is connected to the primary air ring channel (2), the primary air ring channel (2) is connected to the secondary air ring channel (6) through the ring plate (4), the secondary air duct (7) is connected to the secondary air ring channel (6), and the air distribution outer ring channel (8) is connected to the circular tube (9), so as to realize the distribution of primary air and secondary air and then combustion; The hydrogen combustion tube (3) is connected to the mixed gas inlet tube (12), the hydrogen inlet tube (17), and the ring plate (4); the end of the hydrogen combustion tube (3) along the hydrogen flow direction is connected to the hydrogen hole plate (5); A high-voltage ignition rod tube (18) connected to the secondary air duct (7) is also provided in the circular tube (9). The high voltage generated by the high-voltage package is passed through the inner wall of the secondary air duct (7) to generate an electric spark, thereby igniting hydrogen to form a flame.

2. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The primary air ring channel (2) is provided with a plurality of air nozzles, the secondary air ring channel (6) is provided with a plurality of air nozzles, and the air distribution outer ring channel (8) is provided with a plurality of air nozzles; wherein, the primary air ring channel (2) is located at the innermost side of the axis, and mainly provides the oxygen required for initial combustion; the secondary air ring channel (6) is located at the middle side of the axis, and mainly provides the additional oxygen required for complete combustion; the air distribution outer ring channel (8) is located at the outer side of the axis, and mainly used for cooling the outer tube wall of the combustion chamber; after the air volume is distributed through the outer ring channel and the middle ring channel, the air flow rate of the center layer is the smallest, which is the primary air; the air flow rate of the middle ring channel is slightly larger, which is the secondary air, and is used to supplement the oxygen volume during the combustion process, ensure the complete combustion of the fuel, and control the flame shape and temperature distribution; the air volume of the outer ring channel is the largest, and is used for cooling the outer wall of the tube to prevent the burner material from overheating.

3. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The hydrogen orifice plate (5) is provided with a plurality of hydrogen nozzles, and fuel is sprayed to form a jet; the nozzles are divided into three circles, namely, an inner circle, a middle circle, and an outer circle, wherein the middle circle has the largest aperture, and the inner circle and the outer circle have the same and smallest aperture; the large aperture of the middle circle enables more hydrogen to be sprayed out from the middle circle and fully mixed with air to generate a central flame; the small apertures of the inner circle and the outer circle provide uniform airflow distribution, assist in providing a peripheral flame, ensure the stability and uniformity of the entire flame, achieve a better mixing effect of the overall combustion gas, and achieve more complete combustion, thereby reducing the risk of flashback; the large aperture of the middle circle can generate a larger flame and provide a major heat source; and the small apertures of the inner circle and the outer circle can assist in heat distribution, ensuring a more uniform temperature distribution inside and outside the burner.

4. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The number and diameter of the hydrogen nozzles on the hydrogen orifice plate (5) are determined by the specific hydrogen flow rate.

5. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The fan inlet (20) is arranged at the inlet end of the combustion chamber, and the incoming air is blown into the primary air ring channel (2), the secondary air ring channel (6), and the air distribution outer ring channel (8) through the fan inlet (20), and the injection direction is axial.

6. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The number and diameter of the openings of the air nozzles on the primary air duct (2), the secondary air duct (6), and the air distribution outer duct (8) are determined by the specific air distribution volume.

7. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The mixed gas inlet pipe (12) is connected to the SOFC stack anode tail gas, and the hydrogen inlet pipe (17) is connected to low-flow high-purity hydrogen, wherein the SOFC stack anode tail gas refers to a small-flow hydrogen mixed with water vapor, and the volume proportion of hydrogen in the hydrogen and water vapor mixed gas is less than 25%, and the high-purity hydrogen refers to a purity of 99.99% or above.

8. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The fan inlet (20) is connected to the cathode tail gas outlet of the SOFC stack.

9. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The circular tube (9) is provided with a flame detection port (13) and a temperature detection port (14).

10. A low flow hydrogen burner suitable for a solid oxide fuel cell according to claim 1, characterized in that: The burner is provided with a flame observation port (19).

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