Combustion device and method for treating tail gas of solid oxide fuel cell

Abstract

A combustion device and method for treating tail gas from a solid oxide fuel cell, the combustion device comprising: an inner chamber of a combustion chamber, serving as a chamber for the combustion of tail gas from a solid oxide fuel cell; an outer chamber of a combustion chamber, arranged at the periphery of the inner chamber of the combustion chamber, the outer chamber of the combustion chamber being provided with a fluid inlet channel, a fluid outlet channel and an outer chamber rib-shaped annular protrusion, wherein: the fluid inlet channel is used to introduce fluid into the outer chamber of the combustion chamber; the fluid outlet channel is used to outlet the fluid from the outer chamber of the combustion chamber; the outer chamber rib-shaped annular protrusion is staggeredly distributed on both side walls of the outer chamber of the combustion chamber. The present invention also provides a combustion method for treating tail gas from a solid oxide fuel cell. The present invention makes the temperature inside the burner stable and uniform, and the utilization efficiency of the waste heat after combustion is high.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis and combustion, and in particular to a combustion device and method for treating tail gas of a solid oxide fuel cell. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) is a power generation device that directly converts the chemical energy in the fuel into electrical energy under medium and high temperature conditions. It belongs to the third generation of fuel cells, along with Proton Exchange Membrane Fuel Cell (PEMFC). SOFC has high energy conversion efficiency, adopts an all-solid structure, has no leakage or corrosion problems, and has a simple structure and flexible installation. Compared with PEMFC, it has the advantages of being applicable to a wider variety of fuels and not using or using less precious metal catalysts. Therefore, the development prospects of SOFC are very broad. The improvement of SOFC is mainly reflected in the decrease of its operating temperature. The electrolyte conductivity used in the early SOFC was insufficient, and the operating temperature had to be maintained in the high temperature range of 800 to 1000°C. The range of material selection was small and the preparation was difficult. With the thin filmization of battery components and new high conductivity materials (such as doped CeO with fluorite structure), SOFC has a very broad development prospect. 2 ) has emerged, the operating temperature of SOFC can be reduced to the medium temperature zone of 400-750℃, which greatly improves the above problems. Although SOFC technology has made great progress in recent years, the exhaust gas discharged from the SOFC anode has always been a problem to be solved. The anode exhaust gas of SOFC usually contains incompletely converted gases such as methane, carbon monoxide and hydrogen. If it is discharged directly, when the ventilation conditions are poor, the above-mentioned combustible gases will explode after gathering to a certain concentration; in addition, direct discharge will also lead to problems such as fuel waste and heat loss. The SOFC system needs to go through different stages when supplying electricity, and the concentration of fuel in the exhaust gas will also change with the change of power generation, resulting in large fluctuations in the flame propagation speed. At the same time, due to the wide range of flame propagation speed and low fuel concentration, it is very easy to flash back or blow out during the combustion of the exhaust gas, which affects the stability and efficiency of the overall SOFC system. Therefore, the exhaust gas of the SOFC anode must be treated by a subsequent burner to meet the emission standards and recover the waste heat.

[0003] Nowadays, people pay more and more attention to the problem of SOFC tail gas treatment and waste heat recovery, and many scholars have done a lot of related research. At present, the tail gas treatment methods are divided into secondary recovery method, tail gas dilution method and catalytic combustion method.

[0004] However, there are still the following problems in SOFC tail gas combustion treatment:

[0005] (1) The main technical defect: the temperature inside the burner is unstable and unevenly distributed. Since the concentration of combustibles in the exhaust gas emitted by SOFC is greatly affected by the power generation, the burner is in a variable operating state for a long time, the internal temperature changes greatly, and the distribution uniformity is poor. However, most of the burners currently used for SOFC exhaust gas treatment are not equipped with a temperature control system, resulting in poor combustion conditions, extremely poor efficiency, and high nitrogen oxide emissions.

[0006] (2) Minor defect: poor waste heat recovery performance. The gas generated by the exhaust gas of SOFC after combustion in the burner is an important source of waste heat, but the existing technology lacks control over the temperature of this part of the gas, resulting in a large fluctuation range and inability to be effectively utilized, resulting in a large energy loss. Summary of the invention

[0007] In view of this, the main purpose of the present invention is to provide a combustion device and method for treating SOFC tail gas, in order to at least partially solve at least one of the above-mentioned technical problems.

[0008] In order to achieve the above-mentioned purpose, as one aspect of the present invention, a combustion device for treating SOFC exhaust gas is provided, comprising: an inner cavity of a combustion chamber, serving as a chamber for combustion of SOFC exhaust gas; an outer cavity of a combustion chamber, arranged at the periphery of the inner cavity of the combustion chamber, the outer cavity of the combustion chamber is provided with a fluid inlet channel, a fluid outlet channel and an outer cavity fin-like annular protrusion, wherein: the fluid inlet channel is used to introduce fluid into the outer cavity of the combustion chamber; the fluid outlet channel is used to outlet the fluid from the outer cavity of the combustion chamber; the outer cavity fin-like annular protrusions are distributed on both side walls of the outer cavity of the combustion chamber at intervals.

[0009] As another aspect of the present invention, the present invention also provides a combustion method using the combustion device as described above, comprising: mixing external air and SOFC exhaust gas and passing them into the inner cavity of the combustion chamber for combustion; passing fluid into the outer cavity of the combustion chamber to control the combustion temperature of the inner cavity of the combustion chamber.

[0010] It can be seen from the above technical scheme that the combustion device and method for treating SOFC tail gas of the present invention have one or part of the following beneficial effects:

[0011] (1) The combustion device of the present invention has an innovative inner and outer cavity design and an outer cavity fin-type annular protrusion design. The outer cavity fin-type annular protrusion structure can efficiently dissipate the temperature of the inner cavity of the combustion chamber to the outer cavity of the combustion chamber; at the same time, fluids such as coolant flow out through the fluid inlet channel and flow out through the fluid outlet channel, circulate back and forth, and fully contact the outer cavity fin-type annular protrusion structure and the inner cavity of the combustion chamber, which can quickly guide away the temperature of the inner cavity of the combustion chamber, so that the temperature of the inner cavity of the combustion chamber is maintained at the optimal temperature of the catalytic combustion reaction; and because the fluid in the outer cavity of the combustion chamber fully wraps the inner cavity of the combustion chamber, the temperature of the inner cavity of the combustion chamber is kept uniform everywhere.

[0012] (2) When the combustion device of the present invention is used for combustion treatment of SOFC tail gas, the temperature inside the combustion device is stable and uniform, which can stabilize the combustion of tail gas and generate H 2 O and CO 2 etc. harmless gases, reducing NO X The production of. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 1 is a cross-sectional view of the structure of a burner and a schematic diagram of its operation process according to an embodiment of the present invention

[0014] Figure 2 AA is a cross-sectional schematic diagram of a burner vortex forming structure according to an embodiment of the present invention;

[0015] Figure 3A 1 is a schematic cross-sectional view of the burner fin-type annular protrusion structure BB according to an embodiment of the present invention;

[0016] Figure 3B 2 is a schematic cross-sectional view of a burner fin-type annular protrusion structure CC according to an embodiment of the present invention;

[0017] Figure 4 It is a schematic diagram of the burner working process of an embodiment of the present invention.

[0018] Description of reference numerals:

[0019] 1 Exhaust pipe

[0020] 2 Air ducts

[0021] 3 Vortex-formed air ducts

[0022] 4 Exhaust duct

[0023] 5 Fluid inlet channel

[0024] 6 Fluid outlet channel

[0025] 7 Ignition

[0026] 8 External cavity ribbed annular protrusion

[0027] 9 Combustion chamber

[0028] 10 Combustion chamber inner cavity

[0029] AA Cross section of a vortex forming structure

[0030] BB is a cross section of the rib-shaped annular protrusion on the outer wall of the combustion chamber.

[0031] CC Cross section of the ribbed annular protrusion on the inner wall of the combustion chamber DETAILED DESCRIPTION

[0032] In the process of realizing the present invention, it is found that the combustion device can be designed with inner and outer cavities and annular protrusions to achieve the purpose of overall temperature control of the combustion device. The inner and outer cavity design divides the burner into two parts, the annular protrusion structure is evenly distributed in the outer cavity. The principle of fin heat dissipation is used. The annular protrusion structure is essentially a fin, which can efficiently guide the high temperature generated by the combustion of the inner cavity to the outer cavity and transfer it to the fluid (such as coolant) introduced into the outer cavity. Since the fin-type annular protrusion increases the contact area with the fluid, the fluid can better guide the heat transmitted from the inner cavity, and the temperature of the inner cavity can be maintained at a temperature that is most suitable for the catalytic reaction of exhaust gas combustion (making the catalyst work at the optimal temperature), thereby ensuring the uniformity of the temperature inside the burner and the stability of exhaust gas combustion. In addition, by controlling the flow rate and flow rate of the air in the vortex forming air channel, the special vortex forming structure formed by the vortex forming air duct can guide the incoming air to form a vortex at the top of the burner. The vortex can be more fully mixed with the exhaust gas and the temperature of the gas discharged from the burner can be adjusted. It can be used as a stable heat source to improve the working efficiency of SOFC.

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0034] According to an embodiment of the present invention, a combustion device for treating SOFC tail gas is provided, such as Figure 1 As shown, it includes: a combustion chamber cavity 10, which serves as a chamber for SOFC tail gas combustion; a combustion chamber outer cavity 9, which is arranged on the outer periphery of the combustion chamber inner cavity 10, and the combustion chamber outer cavity 9 is provided with a fluid inlet channel 5, a fluid outlet channel 6 and an outer cavity fin-type annular protrusion 8, wherein: the fluid inlet channel 5 is used to introduce fluid into the combustion chamber outer cavity 9; the fluid outlet channel 6 is used to outlet the fluid outside the combustion chamber outer cavity 9; the outer cavity fin-type annular protrusion 8 is distributed on the two side walls of the combustion chamber outer cavity 9 at intervals.

[0035] The inner and outer cavity design of the combustion device divides the combustion device into two parts, the annular protrusion structure is evenly distributed in the outer cavity of the combustion chamber, and uses the principle of fin heat dissipation. The annular protrusion structure is essentially a fin, which can efficiently conduct the high temperature generated by the inner cavity combustion to the outer cavity, and transfer it to the fluid (such as coolant) entering the outer cavity. Since the fin-type annular protrusion of the outer cavity increases the contact area with the fluid, the fluid can better conduct away the heat transferred from the inner cavity, and the temperature of the inner cavity can be maintained at the temperature most suitable for the exhaust gas combustion catalytic reaction (making the catalyst work at the optimal temperature), thereby ensuring the uniformity of the temperature inside the burner and the stability of the exhaust gas combustion.

[0036] According to an embodiment of the present invention, the combustion device further comprises a vortex-shaped air duct, such as Figure 2 As shown, it is located at the upper part of the combustion chamber inner cavity 10 and is tangent to the side wall of the combustion chamber inner cavity 10, and is used to introduce air to generate vortex. This special vortex forming structure formed by the vortex forming air duct and the combustion chamber inner cavity will guide the introduced air to form a vortex at the top of the burner, control the flow rate and flow rate of the air in the air channel, so that the vortex can be more fully mixed with the exhaust gas, neutralize the excessive temperature, and thereby adjust the temperature of the gas discharged from the burner, so that the gas discharged from the burner can be used as a stable heat source to improve the working efficiency of the SOFC.

[0037] According to an embodiment of the present invention, a flow valve is provided in the fluid introduction channel 5, and the flow valve is used to control the fluid flow in the fluid introduction channel 5, thereby maintaining the combustion chamber at different combustion temperatures.

[0038] According to an embodiment of the present invention, the combustion device further comprises a tail gas pipeline 1 for passing the SOFC tail gas into the bottom of the inner cavity of the combustion chamber.

[0039] According to an embodiment of the present invention, the combustion device further comprises an air duct 2 for passing air into the bottom of the combustion chamber inner cavity. More specifically, the air duct 2 is connected to the tail gas duct 1 for mixing the SOFC tail gas and air and passing them into the bottom of the combustion chamber inner cavity together.

[0040] According to an embodiment of the present invention, the tail gas pipeline 1 and the air pipeline 2 are respectively provided with a flow valve and a check valve, the flow valve is used to control the flow rate and adjust it in real time so that the SOFC tail gas and air reach the optimal reaction ratio. The check valve is used to prevent flashback.

[0041] According to an embodiment of the present invention, the combustion device further comprises an igniter 7, which is located in the combustion chamber inner cavity 10 and is used to ignite the SOFC tail gas.

[0042] According to an embodiment of the present invention, a first temperature sensor is attached to the inner wall of the inner cavity of the combustion chamber, and the first temperature sensor is used to monitor the reaction temperature of the inner cavity of the combustion chamber. The flow rate of the external cavity fluid is timely adjusted through feedback from the first temperature sensor, thereby controlling the inner cavity temperature.

[0043] According to an embodiment of the present invention, a catalyst coating is attached to the inner wall of the inner cavity of the combustion chamber, so that the SOFC tail gas is fully in contact with the catalyst, thereby improving the combustion efficiency.

[0044] According to an embodiment of the present invention, the catalyst coating comprises Al 2 O 3 、CeO 2 、ZrO 2 ,La 2 O 3 、 SrO、TiO 2 and at least one of a platinum group metal.

[0045] According to an embodiment of the present invention, the fluid includes fluid air, water or coolant. The fluid can be selected according to the required cooling effect. For example, when excessive cooling is not required, a gas such as air with a small specific heat capacity can be selected, while when rapid cooling is required in a short time, a liquid such as water or coolant with a large specific heat capacity can be selected.

[0046] According to the embodiment of the present invention, the outer cavity rib-type annular protrusions 8 are evenly distributed on the inner and outer side walls of the outer cavity at intervals and staggered along the axial direction of the outer cavity.

[0047] According to an embodiment of the present invention, the cross section of the combustion chamber cavity 10 is circular, and the cross section of the combustion chamber outer cavity 9 is annular.

[0048] According to an embodiment of the present invention, the combustion device also includes a fan and a flow valve, which are located in the vortex-forming air duct 3. The flow rate and flow of the air vortex are controlled by the fan power and the opening and closing of the flow valve, thereby controlling the temperature of the mixed combustion gas.

[0049] According to an embodiment of the present invention, the combustion device also includes an exhaust pipe 4, which is located at the upper part of the inner cavity 10 of the combustion chamber and is connected to the SOFC shell, and is used to wrap the gas discharged from the exhaust pipe 4 to contact the SOFC shell, so as to uniformly insulate the battery, provide a stable heat source for the operation of the battery, and realize efficient utilization of the waste heat after the SOFC exhaust gas is burned.

[0050] According to an embodiment of the present invention, the combustion device also includes a second temperature sensor located in the exhaust duct, which is used to monitor the gas temperature in the exhaust duct. The air flow in the vortex-forming air duct is timely adjusted through feedback from the second temperature sensor, thereby controlling the temperature of the exhaust gas.

[0051] According to an embodiment of the present invention, a combustion method using the combustion device as described above is also provided, comprising: mixing external air and SOFC exhaust gas and passing them into the inner cavity 10 of the combustion chamber for combustion; passing fluid into the outer cavity 9 of the combustion chamber to control the combustion temperature of the inner cavity 10 of the combustion chamber.

[0052] According to an embodiment of the present invention, the combustion method further comprises: passing air into the upper part of the combustion chamber inner cavity 10 through the vortex forming air duct 3 to form a vortex, and mixing the air with the combustion gas of the SOFC to control the temperature of the combustion gas.

[0053] According to an embodiment of the present invention, the combustion method further comprises: after the combustion gas is discharged through the exhaust pipe 4, it is fully wrapped and contacted with the SOFC shell to provide a heat source for the SOFC.

[0054] The following specific embodiments are listed to illustrate the technical solution of the present invention in detail. It should be noted that the following specific embodiments are only used for illustration and are not used to limit the present invention.

[0055] Example

[0056] (I) Combustion device structure for treating SOFC tail gas of the present invention

[0057] The combustion device of this embodiment is composed of an air inlet and outlet system, a catalytic combustion system, and a temperature control system.

[0058] (1) The inlet and outlet gas system includes an exhaust gas pipeline 1, an air pipeline 2, and an exhaust gas pipeline 4. Its functions are to introduce SOFC exhaust gas and discharge high-temperature gas after combustion.

[0059] (2) The catalytic combustion system includes an igniter 7 and a combustion chamber inner cavity 10. A catalyst coating is attached to the inner cavity wall of the combustion chamber 10. Its function is to ignite the SOFC tail gas and catalytically assist combustion.

[0060] (3) The temperature control system includes a vortex-shaped air duct 3, an outer cavity fin-shaped annular protrusion 8, an outer combustion chamber 9, a fluid inlet channel 5 and a fluid outlet channel 6. Its function is to control the temperature of the high-temperature gas after combustion and the entire inner cavity.

[0061] (II) Combustion method process for treating SOFC tail gas in this embodiment

[0062] Preliminary preparation stage:

[0063] The fan sucks in external air, which flows into the turbine-shaped air duct 3, forms a vortex, and prepares for temperature control;

[0064] A fluid (such as coolant, etc.) is introduced into the fluid inlet channel 5 in advance, and the fluid flows out from the fluid outlet channel 6 to prepare for temperature control;

[0065] Catalytic combustion stage:

[0066] The tail gas generated by the SOFC anode is introduced into the tail gas pipeline 1, and the external air is introduced into the air channel 2, and then mixed and enters the combustion chamber 10;

[0067] The igniter 7 ignites the exhaust gas; a catalyst coating is attached to the inner wall of the inner cavity of the combustion chamber, so that the reaction gas and the catalyst are fully in contact, thereby improving the combustion efficiency;

[0068] The air volume is controlled by the flow valve so that the ratio of exhaust gas to air reaches the optimal reaction ratio and is adjusted in real time;

[0069] Waste heat recovery stage:

[0070] The gas after combustion rises due to convection and is discharged from the exhaust pipe 4. The exhaust pipe can be connected to the SOFC shell to allow the gas to fully wrap and contact the battery shell, uniformly insulate the battery, and provide a stable heat source for the battery operation;

[0071] The air channel 3 is a pair of pipes that are tangent to the cylindrical wall of the inner cavity of the combustion chamber and are relatively staggered, so that the incoming air will enter the inner cavity of the combustion chamber and form a vortex. When the gas generated by the combustion of the exhaust gas rises to the top of the inner cavity 10 of the combustion chamber, it encounters the air vortex generated by the vortex forming structure. The air vortex can be more fully mixed with the gas generated after combustion to neutralize the excessively high gas temperature, thereby effectively controlling the temperature. The second temperature sensor in the exhaust pipe 4 will monitor the exhaust gas temperature at any time and provide temperature feedback. The flow rate and flow of the air vortex are controlled by the opening and closing of the fan power and the flow valve, thereby controlling the temperature of the mixed combustion gas;

[0072] Internal temperature control (throughout the whole process):

[0073] There are circles of staggered outer cavity rib-type annular protrusions 8 in the outer cavity 9 of the combustion chamber, which act as ribs and can efficiently dissipate the heat of the inner cavity to the outer cavity; at the same time, when the fluid is introduced through the fluid introduction channel 5, the annular protrusion increases the contact surface area with the fluid, so that the high temperature of the combustion chamber inner cavity is better transferred to the fluid in the inner cavity through the rib-type annular protrusion structure, and the fluid flows out from the fluid outlet channel 6, circulates back and forth, and conducts away the heat of the combustion chamber inner cavity 10. At the same time, the heat transfer rate is adjusted by controlling the fluid flow rate and flow rate, so as to maintain the temperature of the combustion chamber inner cavity 10 at the optimal temperature for the catalytic reaction (the working temperature with the best catalyst activity); the entire burner is cylindrical, and the fluid in the outer cavity 9 of the combustion chamber can well wrap the combustion chamber inner cavity 10, so as to ensure the uniform temperature of the combustion chamber inner cavity 10; the flow rate of the fluid introduction channel 5 is controlled by the flow valve, so as to maintain the combustion chamber at different temperatures; the fluid in the outer cavity 9 of the combustion chamber keeps flowing at a uniform speed and contacts with the entire combustion chamber inner cavity 10, so as to ensure the uniform distribution of the combustion chamber temperature. The first temperature sensor on the inner wall of the combustion chamber 10 will monitor the reaction temperature of the combustion chamber at any time and provide temperature feedback.

[0074] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A combustion device for treating tail gas of a solid oxide fuel cell, comprising: The inner cavity of the combustion chamber serves as a chamber for combustion of exhaust gas from the solid oxide fuel cell; The outer chamber of the combustion chamber is arranged at the outer periphery of the inner chamber of the combustion chamber, and the outer chamber of the combustion chamber is provided with a fluid inlet channel, a fluid outlet channel and an outer chamber fin-type annular protrusion, wherein: A fluid introduction channel, used for introducing fluid into the outer chamber of the combustion chamber; A fluid outlet passage, used for outlet the fluid outside the combustion chamber; The outer cavity rib-shaped annular protrusions are distributed at intervals and staggered on the two side walls of the outer cavity of the combustion chamber; The vortex-forming air duct is located at the upper part of the combustion chamber cavity and is tangent to the side wall of the combustion chamber cavity, and is used to introduce air to generate a vortex; An exhaust pipe is located at the upper part of the inner cavity of the combustion chamber and is connected to the shell of the solid oxide fuel cell, and is used to wrap the gas discharged from the exhaust pipe to contact the shell of the solid oxide fuel cell; Among them, by controlling the flow rate and flow rate of air in the vortex-forming air channel and utilizing the special vortex-forming structure formed by the vortex-forming air duct, the incoming air will be guided to form a vortex at the top of the burner. The vortex can be more fully mixed with the exhaust gas and thereby adjust the temperature of the gas discharged from the burner.

2. The combustion device according to claim 1, wherein: A flow valve is arranged in the fluid introduction channel.

3. The combustion device according to claim 1, wherein: The combustion device also includes an exhaust gas pipeline for passing the exhaust gas of the solid oxide fuel cell into the bottom of the inner cavity of the combustion chamber; The combustion device also includes an air duct for passing air into the bottom of the combustion chamber; The tail gas pipeline and the air pipeline are respectively provided with a flow valve and a check valve.

4. The combustion device according to claim 1, wherein: The combustion device also includes an igniter, which is located in the inner cavity of the combustion chamber; A first temperature sensor is attached to the inner wall of the inner cavity of the combustion chamber, for monitoring the reaction temperature of the inner cavity of the combustion chamber; The inner wall of the inner cavity of the combustion chamber is provided with a catalyst coating; The catalyst coating includes at least one of Al2O3, CeO2, ZrO2, La2O3, SrO, TiO2 and platinum group metals.

5. The combustion device according to claim 1, wherein: The fluid includes fluid air, water or coolant; The outer cavity rib-shaped annular protrusions are staggered and evenly distributed along the axial direction of the outer cavity on the inner and outer side walls of the outer cavity; The cross section of the inner cavity of the combustion chamber is circular, and the cross section of the outer cavity of the combustion chamber is annular.

6. The combustion device according to claim 1, wherein: The combustion device further comprises a fan and a flow valve, which are located in the vortex-forming air duct.

7. The combustion device according to claim 1, wherein: The combustion device further comprises a second temperature sensor located in the exhaust pipe and used for monitoring the gas temperature in the exhaust pipe.

8. A combustion method using the combustion device according to any one of claims 1 to 7, comprising: Mixing external air and exhaust gas from the solid oxide fuel cell into the combustion chamber for combustion; A fluid is introduced into the outer chamber of the combustion chamber to control the combustion temperature of the inner chamber of the combustion chamber.

9. The combustion method according to claim 8, wherein: The combustion method further comprises: Passing air into the upper part of the inner cavity of the combustion chamber through a vortex-forming air duct to form a vortex, and mixing it with the combustion gas of the solid oxide fuel cell tail gas to control the temperature of the combustion gas; and / or After the combustion gas is discharged through the exhaust pipe, it fully wraps and contacts the shell of the solid oxide fuel cell, providing a heat source for the solid oxide fuel cell.

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