Combustion chamber nozzle of fuel cell system, combustion chamber and flame tube air inlet method

Abstract

The invention relates to a combustion chamber nozzle of a fuel cell system, which comprises an inner cylinder and an outer cylinder, the outer cylinder is coaxially sleeved outside the inner cylinder, the outer diameter of the inner cylinder is smaller than the inner diameter of the outer cylinder, an annular space between the inner cylinder and the outer cylinder forms a rotational flow cathode tail gas inlet channel, a bluff body is coaxially arranged in the inner cylinder, the bluff body is cylindrical, and the outer diameter of the bluff body is smaller than the inner diameter of the outer cylinder. An end plate is arranged at the gas outlet end of the bluff body, through holes are densely distributed in the end plate, the outer diameter of the bluff body is smaller than the inner diameter of the inner cylinder, an annular space between the bluff body and the inner cylinder forms a rotational flow anode tail gas inlet channel, and a shaft hole of the bluff body forms a direct current anode tail gas inlet channel. The invention further relates to a combustion chamber adopting the combustion chamber nozzle and a flame tube air inlet method adopting the combustion chamber. The combustion mode that rotational flow diffusion is combined with bluff body flame stabilization is adopted, stable combustion of the combustion chamber under the conditions that gas composition changes are complex, residual gas coefficients are variable and the combustion heat value is extremely low is achieved, the stability of combustion flames is improved, and the outlet temperature of the combustion chamber is evenly distributed.

Description

Technical Field

[0001] The invention relates to a combustion chamber nozzle, a combustion chamber and a flame tube air intake method of a fuel cell system, and belongs to the technical field of solid oxide fuel cells. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) belongs to the third generation of fuel cells. It is an all-solid-state chemical power generation device that directly converts chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner at medium and high temperatures. It is one of the fuel cells with the highest theoretical energy density. SOFC has the advantages of wide fuel adaptability, high energy conversion efficiency, and near-zero pollution. Its electrical conversion efficiency can reach more than 65%. It has broad application prospects in civil fields such as large-scale centralized power supply, medium-sized power distribution, and small household cogeneration as a fixed power station, as well as as a mobile power source such as ship power source and transportation vehicle power source.

[0003] As the core component of the thermal balance of the SOFC system, the combustion chamber plays a role in heating up the entire system during the system startup phase, so that the stack meets the requirements of the power generation conditions. During the stable power generation phase of the system, the residual fuel in the tail gas of the stack is burned out to maintain the high-temperature operation of the system. The gas composition of the SOFC system varies during the heating phase, from the initial hydrocarbon gas fuel to the introduction of water vapor. As the reforming reaction proceeds, hydrogen and carbon monoxide appear in the fuel components, and carbon dioxide and water vapor also appear at the same time, and different heating stages have different residual gas coefficients; during the power generation operation phase of the system, since the gas composition entering the combustion chamber is the unreacted tail gas in the stack, the calorific value of the anode gas is very low, and the oxygen content in the cathode gas is also low. Therefore, how to achieve stable combustion in the combustion chamber under the conditions of complex gas composition changes, variable residual gas coefficients, and extremely low fuel calorific value is the main difficulty in the structural design of the SOFC combustion chamber. Since the calorific value of the fuel is extremely low under power generation conditions, and the flow of fuel and air under various conditions fluctuates, combustion stability has always been a difficult problem to solve. At present, the combustion organization mode used in SOFC system is mostly catalytic combustion or porous medium premixed combustion. Catalytic combustion requires expensive catalysts and has a limited service life. Porous medium premixed combustion currently has very poor impact and vibration resistance due to the poor toughness of porous medium materials, and its long service life is limited. In addition, excessive pressure loss will affect the overall working stability of the system. The combustion chamber used also has problems such as uneven outlet temperature distribution, easy backfire erosion of the nozzle, and excessively high flame tube temperature affecting the service life. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a combustion chamber nozzle, a combustion chamber and a flame tube air intake method for a fuel cell system, which adopts a combustion mode of swirl diffusion combined with blunt body flame stabilization to achieve stable combustion of the SOFC system under all working conditions.

[0005] The technical solution for achieving the above-mentioned purpose of the present invention is: a combustion chamber nozzle of a fuel cell system comprises an inner cylinder and an outer cylinder, the outer cylinder is coaxially sleeved outside the inner cylinder, the outer diameter of the inner cylinder is smaller than the inner diameter of the outer cylinder, the annular space between the inner cylinder and the outer cylinder constitutes a swirl cathode tail gas inlet channel, a blunt body is coaxially arranged in the inner cylinder, the blunt body is cylindrical, an end plate is arranged at its gas outlet end, the end plate is densely covered with through holes, the outer diameter of the blunt body is smaller than the inner diameter of the inner cylinder, the annular space between the blunt body and the inner cylinder constitutes a swirl anode tail gas inlet channel, and the axial hole of the blunt body constitutes a DC anode tail gas inlet channel.

[0006] Preferably, the through holes on the end plate are divided into multiple groups, each group has multiple through holes, and the multiple groups of through holes are evenly distributed on the end plate along different circumferences with the center of the end plate as the center.

[0007] Furthermore, in each group of through holes, the apertures of the through holes distributed along the circumference of the smallest radius are smaller than the apertures of the through holes distributed along the circumferences of other radii.

[0008] Preferably, the through holes on the end plate have a diameter of 0.5-3 mm and a number of 5-20 holes.

[0009] Preferably, a throttling orifice plate is provided on the air outlet side of the blunt body, the throttling orifice plate is parallel to the end plate, and a spacing is left between the two, the throttling orifice plate is densely covered with throttling holes, the throttling holes can be divided into multiple groups, each group of throttling holes has multiple numbers, and multiple groups of throttling holes are evenly distributed on the throttling orifice plate along different circles with the center of the throttling orifice plate as the center.

[0010] Preferably, the throttling holes on the throttling orifice plate and the through holes on the end plate are staggered and distributed in the axial direction.

[0011] Preferably, the diameter of the throttling holes is 0.5-2.5 mm, and the number of the throttling holes is 3-10.

[0012] Preferably, the bluff body comprises a first inner diameter gradually expanding section, an inner diameter constant diameter section and a second inner diameter gradually expanding section in sequence from the air inlet end to the air outlet end, and the outer wall of the first inner diameter gradually expanding section is streamlined with a (convex outward) arc transition.

[0013] Preferably, the inner cylinder includes a constant inner diameter section and a gradually expanding inner diameter section from the air inlet end to the air outlet end, the second gradually expanding inner diameter section of the blunt body is located in the gradually expanding inner diameter section of the inner cylinder, and the first gradually expanding inner diameter section of the blunt body and the constant inner diameter section are located in the constant inner diameter section of the inner cylinder.

[0014] Preferably, the outer cylinder comprises a constant inner diameter section and a gradually expanding inner diameter section from the air inlet end to the air outlet end, and the gradually expanding inner diameter section of the inner cylinder is located inside the gradually expanding inner diameter section of the outer cylinder.

[0015] Preferably, the second inner diameter gradually expanding section of the bluff body, the inner diameter gradually expanding section of the inner cylinder and the inner diameter gradually expanding section of the outer cylinder have the same or similar gradually expanding arcs or gradually expanding slopes.

[0016] Preferably, the air outlet ends of the bluff body, the inner cylinder and the outer cylinder are flush, and the air inlet end of the inner cylinder protrudes outward, that is, the length of the inner cylinder is longer than the length of the outer cylinder and the length of the bluff body.

[0017] Preferably, swirl components are provided in both the swirl cathode tail gas inlet passage and the swirl anode tail gas inlet passage.

[0018] Preferably, the swirl component is a swirl blade.

[0019] A combustion chamber of a fuel cell system comprises a combustion chamber casing and a flame tube, the flame tube being coaxially located in the combustion chamber casing, an anode tail gas inlet being provided on the side wall of the combustion chamber casing, a cathode tail gas inlet being provided on the head end wall or the side wall of the combustion chamber casing, end wall through holes being densely distributed on the head end wall of the flame tube, a plurality of side wall through holes being provided on the side wall of the flame tube, a gap being left between the head end wall of the flame tube and the head end wall of the combustion chamber casing, an anode tail gas collecting chamber being provided in the gap and being connected to the anode tail gas inlet (can be connected through a pipeline, which can be called an anode tail gas inlet pipe), a combustion chamber nozzle being provided between the anode tail gas collecting chamber and the flame tube, the combustion chamber nozzle adopts any one of the combustion chamber nozzles of the fuel cell system disclosed in the present invention, the swirl anode tail gas inlet channel and the DC anode tail gas inlet channel both connect the anode tail gas collecting chamber and the flame tube, and the swirl cathode tail gas inlet channel connects the internal space of the combustion chamber casing and the flame tube.

[0020] Preferably, the side wall through holes include flow guiding and mixing holes, cooling inclined holes and mixing straight holes. The number of the flow guiding and mixing holes is multiple and they are evenly distributed along the same circumference of the radial direction on the side wall of the flame tube. The flow guiding and mixing holes are provided with flow guiding flanges (or flow guiding bushings). The cooling inclined holes are inclined from the outside of the flame tube to the inside of the flame tube from the head end to the tail end, and the angle between the cooling inclined holes and the side wall surface of the flame tube is 25-40°. The cooling inclined holes are divided into several groups, and the number of cooling inclined holes in each group is multiple. Several groups of cooling inclined holes are arranged on the side wall of the flame tube along different circumferences of the radial direction. The spacing is uniformly distributed, the cooling inclined holes are distributed from the upstream to the downstream of the guide mixing hole (that is, from the flame tube head end side to the end direction side of the guide mixing hole), the number of the mixing straight holes is multiple, and they are uniformly distributed along the same radial circumference on the side wall of the flame tube, or the mixing straight holes are divided into several groups, each group of mixing straight holes has multiple numbers, and several groups of mixing straight holes are uniformly distributed along different radial circumferences on the side wall of the flame tube at equal spacing, and the mixing straight holes are located downstream of the cooling inclined hole (that is, located on the flame tube end direction side of the cooling inclined hole).

[0021] Preferably, the distance between the guide mixing hole and the head end wall of the flame tube is the same as the diameter of the flame tube.

[0022] Preferably, the diameter of the diversion and mixing holes is 10-25 mm, and the number of the diversion and mixing holes is 4-12.

[0023] Preferably, the radius of the guide flange is 3-10 mm.

[0024] Preferably, the diameter of the cooling inclined hole is 0.5-2 mm.

[0025] Preferably, adjacent groups of inclined cooling holes are staggered, the axial spacing between adjacent groups of inclined cooling holes is 5-25 mm, and the hole spacing between adjacent inclined cooling holes in each group of inclined cooling holes is 3-10 mm.

[0026] Preferably, the mixing straight holes may be 1-4 groups, the number of mixing straight holes in each group is 6-18, and the hole diameter is 6-20 mm.

[0027] Preferably, a splash plate with a circular outer edge is coaxially provided on the head end wall side of the flame tube, the diameter of the splash plate is smaller than the inner diameter of the head of the flame tube, and a distance is left between the splash plate and the head end wall of the flame tube, forming an air inlet channel of the flame tube head for cathode tail gas, and a nozzle insertion seat is provided on the splash plate, and the outlet end of the combustion chamber nozzle is inserted into the nozzle insertion seat and sealed.

[0028] Preferably, the splash plate and the head end wall of the flame tube are an integral structure, connected by a bracket or a suitable supporting structure, the nozzle insert seat adopts a floating ring structure, and the sealing method between the air outlet end of the combustion chamber nozzle and the splash plate and the head end wall of the flame tube is a floating ring seal.

[0029] Preferably, the end wall through holes are divided into several groups, each group of end wall through holes has several numbers, and the several groups of end wall through holes are evenly distributed on the head end wall of the flame tube along different circumferences with the center of the head end wall as the center.

[0030] Furthermore, adjacent groups of end wall through holes are staggered in radial direction.

[0031] Preferably, in each group of end wall through holes, the distribution density of the end wall through holes distributed along the circumference of the smallest radius is smaller than the distribution density of the end wall through holes distributed along the circumference of other radii.

[0032] Preferably, the diameter of the end wall through holes is 1-3 mm, and the hole spacing between adjacent end wall through holes in each group of end wall through holes is 3-8 mm.

[0033] Preferably, the combustion chamber casing and the flame tube are both straight cylindrical, and the end of the flame tube is axially slidingly matched with the end of the combustion chamber casing. An inwardly extending annular flange can be provided at the air outlet end of the combustion chamber casing, and the end of the flame tube and the annular flange are axially slidingly connected by a sliding fit structure (such as a groove rail structure), and the head end of the flame tube is suspended on the inner wall of the combustion chamber casing.

[0034] Preferably, the igniter (usually an ignition rod) of the combustion chamber extends horizontally into the flame tube from the outer side of the head end of the combustion chamber casing, and the head end wall of the combustion chamber casing, the side walls of the anode tail gas collecting chamber or the anode tail gas inlet pipe, the head end wall of the flame tube and the splash plate are all provided with igniter holes for the igniter to pass through, and a horizontal igniter sleeve is provided in the anode tail gas collecting chamber or the anode tail gas inlet pipe to form an igniter channel, and the two ends of the igniter sleeve are respectively sealed and connected to the igniter holes on the side walls of the anode tail gas collecting chamber or the anode tail gas inlet pipe.

[0035] In the flame tube air intake method of a fuel cell system of a combustion chamber of any fuel cell system disclosed in the present invention, the anode tail gas of the fuel cell stack enters the flame tube in the following anode tail gas intake manner: (1) The swirl flow anode tail gas enters the flame tube from the swirl flow anode tail gas inlet passage; (2) entering the flame tube from the axial hole of the blunt body; The cathode tail gas of the fuel cell stack enters the flame tube in the following cathode tail gas intake method: (1) entering the flame tube from the side wall through holes distributed on the side wall of the flame tube; (2) entering the flame tube from the end wall through holes distributed on the end wall of the head of the flame tube; (3) the swirl cathode tail gas enters the flame tube in a swirl manner from the swirl cathode tail gas inlet passage; The cathode exhaust gas entering the flame tube in a swirl manner wraps the anode exhaust gas entering the flame tube in a swirl manner and entering the flame tube from the axial hole of the blunt body in an intake direction.

[0036] The anode exhaust swirl from the outlet end of the swirl anode exhaust inlet channel and the anode exhaust from the outlet end of the blunt body drive the cathode exhaust from the outlet end of the swirl cathode exhaust inlet channel to form an outer swirl by relying on negative pressure and suction, and gradually mix and burn during the axial flow.

[0037] The cathode exhaust gas that enters the flame tube using the cathode exhaust gas intake method (2) enters the rear side of the splash plate in the flame tube through the intake channel at the flame tube head to participate in combustion.

[0038] Preferably, the amount of anode exhaust gas entering the flame tube using the anode exhaust gas intake method (1) is 80-95% of the total amount of anode exhaust gas intake, the amount of anode exhaust gas entering the flame tube using the anode exhaust gas intake method (2) is 5-20% of the total amount of anode exhaust gas intake, the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (1) is 65-92% of the total amount of cathode exhaust gas intake, the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (2) is 3-15% of the total amount of cathode exhaust gas intake, and the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (3) is 5-20% of the total amount of cathode exhaust gas intake.

[0039] Furthermore, in the cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (1), the amount of cathode exhaust gas entering the flame tube from the guide mixing hole is 10-35% of the total cathode exhaust gas intake, the amount of cathode exhaust gas entering the flame tube from the mixing straight hole is 15-50% of the total cathode exhaust gas intake; the amount of cathode exhaust gas entering the flame tube from the cooling inclined hole is 5-30% of the total cathode exhaust gas intake.

[0040] The beneficial effects of the present invention are: (1) The present invention adopts a combustion method of swirl diffusion combined with blunt body flame stabilization. After the igniter works, a diffusion combustion flame is formed in which a swirl cathode tail gas wraps a swirl anode tail gas downstream of the combustion chamber nozzle in the flame tube. Most of the anode tail gas enters the flame tube in a swirl manner, and a small part of the anode tail gas enters the flame tube in a direct current manner, so that a flame recirculation zone can be formed downstream of the blunt body under different airflow conditions. Under the combined effect of the recirculation zone formed by the swirl and the recirculation zone formed by the direct current, the stable combustion is ensured under various conditions. Under the starting condition, a weak airflow forms a vortex structure at the edge of the blunt body to stabilize the flame. Under these conditions, a large amount of anode tail gas forms a strong reflux zone downstream of the blunt body through swirl to stabilize the flame. Combined with the design that cathode tail gas enters the flame tube in multiple ways, stable combustion is achieved in the combustion chamber under the conditions of complex gas composition changes, variable residual gas coefficients, and extremely low combustion calorific value, thereby improving the stability of the combustion flame and solving the problems of unstable combustion and uneven outlet temperature distribution caused by fuel characteristics (complex composition changes, wide residual gas coefficient changes, extremely low calorific value, etc.) in the combustion chamber of the solid oxide fuel cell system. Stable combustion of ultra-low calorific value fuel with a calorific value of 1150kJ / kg can be achieved, and the outlet temperature distribution of the combustion chamber is uniform. (2) The gas outlet end of the bluff body adopts a double-layer impact divergent hole structure design, which can effectively avoid flame backflow ablation of the combustion chamber nozzle; (3) The cathode exhaust gas of the present invention enters the flame tube from the through hole of the end wall of the flame tube, impacts the splash plate after entering the flame tube, and enters the rear side of the splash plate in the flame tube from the flame tube head air inlet passage formed between the splash plate and the head end wall of the flame tube, which can form air film cooling, divergent cooling or composite cooling for the head end wall of the flame tube and the splash plate, thereby playing a cooling and thermal protection role for the head end wall of the flame tube and the splash plate, thereby extending the service life of the flame tube; (4) The combustion chamber of the present invention has the advantages of compact structure, low cost, stable combustion of ultra-low calorific value fuel, low pollution emission, uniform outlet temperature distribution and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic cross-sectional structural diagram of an embodiment of the combustion chamber nozzle of the present invention; Figure 2 is a schematic cross-sectional structural diagram of an embodiment of the combustion chamber of the present invention; Figure 3 is a schematic cross-sectional structural diagram of an embodiment of the flame tube of the present invention; Figure 4 It is a structural schematic diagram of an implementation mode of the head end wall of the flame tube of the present invention. DETAILED DESCRIPTION

[0042] See also Figure 1 The present invention discloses a combustion chamber nozzle (or swirler) 1 of a fuel cell system (solid oxide fuel cell SOFC system), comprising an inner cylinder 2 and an outer cylinder 3, wherein the outer cylinder is coaxially sleeved outside the inner cylinder, and the two can be fixedly connected by a bracket or other suitable supporting structure, the outer diameter of the inner cylinder is smaller than the inner diameter of the outer cylinder, and the annular space between the inner cylinder and the outer cylinder constitutes a swirling cathode tail gas inlet channel 4 for swirling cathode tail gas, a blunt body 5 is coaxially arranged in the inner cylinder, the blunt body is cylindrical, and an end plate 6 is arranged at its gas outlet end, and through holes are densely distributed on the end plate, the outer diameter of the blunt body is smaller than the inner diameter of the inner cylinder, the annular space between the blunt body and the inner cylinder constitutes a swirling anode tail gas inlet channel 7 for swirling anode tail gas, and the axial hole of the blunt body (or the hollow space in the blunt body) constitutes a DC anode tail gas inlet channel 8 for conveying anode tail gas. The swirl components 9 are both provided in the swirl cathode tail gas inlet channel and the swirl anode tail gas inlet channel, so as to generate swirl in the gas passing through the corresponding inlet channels.

[0043] The through holes on the end plate are preferably divided into multiple groups, each group has multiple through holes, and the multiple groups of through holes are evenly distributed on the end plate along different circumferences with the center of the end plate as the center. The apertures of the through holes distributed along the circumference with the smallest radius in each group of through holes are preferably smaller than the apertures of the through holes distributed along the circumferences with other radii. The apertures of the through holes on the end plate are preferably 0.5-3 mm, and the number is preferably 5-20.

[0044] A throttling orifice plate 10 is preferably provided on the air outlet side of the blunt body, wherein the throttling orifice plate is parallel to the end plate with a spacing therebetween, and the throttling orifice plate is densely covered with throttling holes, which can be divided into multiple groups, each group of throttling holes having multiple numbers, and multiple groups of throttling holes are evenly distributed on the throttling orifice plate along different circles with the center of the throttling orifice plate as the center.

[0045] The throttle holes on the throttle orifice plate are preferably arranged in an axially staggered distribution with the through holes on the end plate. The aperture of the throttle holes is preferably 0.5-2.5 mm, and the number is preferably 3-10. The throttle orifice plate is mainly used to control the gas volume distribution ratio of the anode tail gas passing through the axial hole of the blunt body and the cyclonic anode tail gas inlet channel.

[0046] The throttling holes on the throttling orifice plate and the through holes on the end plate together constitute an outlet passage at the outlet end of the blunt body. The throttling holes on the throttling orifice plate serve as impact holes, and the through holes on the end plate serve as divergent holes. With such an arrangement, a small portion of anode exhaust gas will be discharged through the outlet passage at the outlet end of the blunt body, so that the flame reflux will not directly impact the outlet end of the blunt body, which can effectively prevent backfire from ablating the nozzle.

[0047] The bluff body preferably includes a first inner diameter gradually expanding section, a constant inner diameter section, and a second inner diameter gradually expanding section in sequence from the air inlet end to the air outlet end, and the outer wall of the first inner diameter gradually expanding section is streamlined with a (convex) arc transition. The inner cylinder preferably includes a constant inner diameter section and a gradually expanding inner diameter section in sequence from the air inlet end to the air outlet end, and the second inner diameter gradually expanding section of the bluff body is located in the inner diameter gradually expanding section of the inner cylinder, and the first inner diameter gradually expanding section and the constant inner diameter section of the bluff body are located in the inner diameter gradually expanding section of the inner cylinder. The outer cylinder preferably includes a constant inner diameter section and a gradually expanding inner diameter section in sequence from the air inlet end to the air outlet end, and the inner diameter gradually expanding section of the inner cylinder is located in the inner diameter gradually expanding section of the outer cylinder. The gradually expanding arc or gradually expanding slope of the second inner diameter gradually expanding section of the bluff body, the inner diameter gradually expanding section of the inner cylinder, and the inner diameter gradually expanding section of the outer cylinder are preferably the same or close. Such arrangement enables the gas entering the flame tube through the combustion chamber nozzle to diffuse outward from the center, thereby facilitating diffusion combustion.

[0048] The outlet ends of the bluff body, the inner cylinder and the outer cylinder are preferably flush for easy installation. The inlet end of the inner cylinder extends outward, that is, the length of the inner cylinder is longer than the length of the outer cylinder and the length of the bluff body, which is convenient for connection with the anode tail gas delivery pipeline or gas collection device, and does not affect the cathode tail gas entering the cyclonic cathode tail gas inlet channel.

[0049] The swirl components in the swirl anode tail gas inlet channel are preferably straight blades or guide blades, the blades are fixedly connected to the outer wall of the blunt body and / or the inner wall of the inner cylinder, the inclination angle of the blades is preferably 25-60°, the number is preferably 6-18, and they are evenly distributed along the same circumference.

[0050] The swirl components in the swirl cathode tail gas inlet channel are preferably axial direct current blades, axial guide blades, radial direct current blades, radial guide blades or radial slot channels, etc. When the swirl components are blades, the blades are fixedly connected to the outer wall of the inner cylinder and / or the inner wall of the outer cylinder, and the inclination angle of the blades or slot channels is preferably 25-60°, and the number is preferably 6-20, which are evenly distributed along the same circumference.

[0051] See also Figure 2-Figure 4The present invention also discloses a combustion chamber of a fuel cell system, comprising a combustion chamber casing 11 and a flame tube 12, both of which are straight-cylindrical in shape. The flame tube is coaxially located in the combustion chamber casing. The flame tube can adopt a single-tube thin-wall structure with a wall thickness of 2-5 mm. An anode tail gas inlet is provided on the side wall of the combustion chamber casing. A cathode tail gas inlet is provided on the head end wall or side wall of the combustion chamber casing, for the anode tail gas and cathode tail gas of the fuel cell stack to enter the combustion chamber. The head end wall 13 of the flame tube is densely covered with end wall through holes 14, for part of the cathode tail gas to enter the flame tube from the head end wall of the flame tube. A plurality of side wall through holes are provided on the side wall of the flame tube, for part of the cathode tail gas to enter the flame tube from the side wall of the flame tube. The head end wall of the flame tube is connected to the combustion chamber casing. A spacing is left between the head end walls, and an anode tail gas collecting chamber 16 connected to the anode tail gas inlet (can be connected through a pipeline, the pipeline can be called an anode tail gas inlet pipe 15) is provided in the spacing, and a combustion chamber nozzle is provided between the anode tail gas collecting chamber and the flame tube for spraying anode tail gas and cathode tail gas into the flame tube, and the combustion chamber nozzle adopts any one of the combustion chamber nozzles of the fuel cell system disclosed in the present invention, the swirl anode tail gas inlet channel and the DC anode tail gas inlet channel are both connected to the anode tail gas collecting chamber and the flame tube, and are used for the anode tail gas intake of the flame tube, and the swirl cathode tail gas inlet channel connects the internal space of the combustion chamber casing with the flame tube, and is used for part of the cathode tail gas to enter the flame tube through the swirl cathode tail gas inlet channel.

[0052] The side wall through holes preferably include guide and mixing holes 17, cooling inclined holes 18 and mixing straight holes 19. The number of the guide and mixing holes is multiple and they are evenly distributed along the same radial circumference on the side wall of the flame tube. The guide and mixing holes are provided with guide flanges (or guide bushings), which are beneficial to the cathode exhaust gas entering the flame tube through the guide and mixing holes to penetrate deeper and mix with the high-temperature combustion zone at the head of the flame tube to form a uniform temperature field. The inclined cooling holes are inclined from the outside of the flame tube to the inside of the tube from the head end to the tail end, and the angle between the inclined cooling holes and the side wall surface of the flame tube is 25-40°. The inclined cooling holes are divided into several groups, and each group of inclined cooling holes has multiple numbers. Several groups of inclined cooling holes are evenly distributed at equal intervals along different radial circles on the side wall of the flame tube. The inclined cooling holes are distributed from the upstream to the downstream of the guide and mixing holes (that is, from the flame tube head end side to the tail end side of the guide and mixing holes). The inclined cooling holes are mainly used for wall cooling and thermal protection of the flame tube to ensure that the wall material is not ablated by high-temperature heat sources. The number of the mixing straight holes is multiple and they are evenly distributed along the same radial circle on the side wall of the flame tube, or the mixing straight holes are divided into several groups, each group of mixing straight holes has multiple mixing straight holes, and several groups of mixing straight holes are evenly distributed at equal intervals along different radial circles on the side wall of the flame tube. The mixing straight holes are located downstream of the cooling inclined holes (i.e., located on the flame tube end direction side of the cooling inclined holes), and are mainly used to further mix the temperature in the flame tube evenly.

[0053] The distance between the diversion mixing hole and the head end wall of the flame tube is preferably the same as the diameter of the flame tube. The diameter of the diversion mixing hole is preferably 10-25 mm, and the number is preferably 4-12. The radius of the diversion flange is preferably 3-10 mm.

[0054] The diameter of the cooling inclined holes is preferably 0.5-2 mm. Adjacent groups of cooling inclined holes are preferably staggered to improve the cooling and thermal protection effect of the wall surface. The axial spacing between adjacent groups of cooling inclined holes is preferably 5-25 mm, and the hole spacing between adjacent cooling inclined holes in each group of cooling inclined holes is preferably 3-10 mm.

[0055] The mixing straight holes can be 1-4 groups, the number of mixing straight holes in each group is preferably 6-18, and the hole diameter is preferably 6-20 mm. When the mixing straight holes are in several groups, the mixing straight holes in adjacent groups can be staggered to ensure uniform air intake.

[0056] A splash plate 20 with a circular outer edge is coaxially provided on the head end wall side of the flame tube. The diameter of the splash plate is smaller than the inner diameter of the head of the flame tube, and a distance is left between the head end wall of the flame tube to form an air inlet passage for the flame tube head of the cathode exhaust gas. The cathode exhaust gas enters the flame tube from the end wall through hole on the head end wall of the flame tube, enters the rear side of the splash plate in the flame tube through the flame tube head air inlet passage to participate in combustion, and a nozzle insertion seat 21 is provided on the splash plate and the head end wall of the flame tube, and the gas outlet end of the combustion chamber nozzle is inserted into the nozzle insertion seat and sealed.

[0057] The splash plate and the head end wall of the flame tube can be an integral structure, connected by a bracket or a suitable supporting structure. The nozzle insert seat adopts a floating ring structure for easy installation. The sealing method between the air outlet end of the combustion chamber nozzle and the splash plate and the head end wall of the flame tube is a floating ring seal.

[0058] The cathode exhaust gas enters the flame tube from the through hole of the end wall of the flame tube, impacts the splash plate after entering the flame tube, and enters the rear side of the splash plate in the flame tube from the flame tube head air inlet channel formed between the splash plate and the head end wall of the flame tube, which can form air film cooling, divergent cooling or compound cooling for the head end wall of the flame tube and the splash plate, thereby cooling and thermally protecting the head end wall of the flame tube and the splash plate, thereby extending the service life of the flame tube.

[0059] The end wall through holes are preferably divided into several groups, each group of end wall through holes has several numbers, and the end wall through holes of several groups are evenly distributed along different circumferences with the center of the end wall of the head as the center. The end wall through holes of adjacent groups are preferably staggered in the radial direction to make the air intake uniform. The distribution density of the end wall through holes distributed along the circumference with the smallest radius in each group of end wall through holes is preferably less than the distribution density of the end wall through holes distributed along the circumferences with other radii. The hole diameter of the end wall through holes is preferably 1-3 mm, and the hole spacing between adjacent end wall through holes in each group of end wall through holes is preferably 3-8 mm.

[0060] The end of the flame tube is preferably axially slidably matched with the end of the combustion chamber casing. An annular flange extending inwardly may be provided at the gas outlet end of the combustion chamber casing. The end of the flame tube and the annular flange are axially slidably connected by a sliding matching structure (e.g., a groove rail structure). The head end of the flame tube is hung on the inner wall of the combustion chamber casing. For example, a hanging ear is fixedly provided on the inner wall of the combustion chamber casing. The head end of the flame tube is hung on the hanging ear. The number of the hanging ears may be multiple, and they are appropriately arranged on the inner wall of the combustion chamber casing according to the installation position of the flame tube in the combustion chamber casing. With such an arrangement, the flame tube can move freely downstream after expanding due to the heat of combustion.

[0061] The anode tail gas inlet pipe can extend outward from the combustion chamber casing to facilitate connection with other equipment or devices.

[0062] In practical applications, the anode tail gas collecting chamber may not be provided in the combustion chamber casing. When the anode tail gas collecting chamber is not provided, the anode tail gas inlet pipe is bent and directly connected to the swirl anode tail gas inlet channel and the DC anode tail gas inlet channel.

[0063] The igniter of the combustion chamber (usually an ignition rod, not shown in the figure) extends horizontally from the outside of the head end of the combustion chamber casing into the flame tube, and the head end wall of the combustion chamber casing, the side walls of the anode tail gas collecting chamber or the anode tail gas inlet pipe, the head end wall of the flame tube and the splash plate are all provided with igniter holes for the igniter to pass through, and the anode tail gas collecting chamber or the anode tail gas inlet pipe is provided with a horizontal igniter sleeve to form an igniter channel, and the two ends of the igniter sleeve are respectively sealed and connected to the igniter holes on the side walls of the anode tail gas collecting chamber or the anode tail gas inlet pipe.

[0064] The present invention also discloses a flame tube air intake method of a fuel cell system using a combustion chamber of any fuel cell system disclosed in the present invention, wherein the anode tail gas of the fuel cell stack enters the flame tube using the following anode tail gas intake method: (1) The swirl flow anode tail gas enters the flame tube from the swirl flow anode tail gas inlet passage; (2) entering the flame tube from the axial hole of the blunt body; The cathode tail gas of the fuel cell stack enters the flame tube in the following cathode tail gas intake method: (1) entering the flame tube from the side wall through holes distributed on the side wall of the flame tube; (2) entering the flame tube from the end wall through holes distributed on the end wall of the head of the flame tube; (3) the swirl cathode tail gas enters the flame tube in a swirl manner from the swirl cathode tail gas inlet passage; The cathode exhaust gas entering the flame tube in a swirl manner wraps the anode exhaust gas entering the flame tube in a swirl manner and entering the flame tube from the axial hole of the blunt body in an intake direction, thereby playing a role in flame stabilization.

[0065] The anode exhaust swirl from the outlet end of the swirl anode exhaust inlet channel and the anode exhaust from the outlet end of the blunt body drive the cathode exhaust from the outlet end of the swirl cathode exhaust inlet channel to form an outer swirl by relying on negative pressure and suction, and gradually mix and burn during the axial flow.

[0066] The cathode exhaust gas that enters the flame tube using the cathode exhaust gas intake method (2) enters the rear side of the splash plate in the flame tube through the intake channel at the flame tube head to participate in combustion.

[0067] The amount of anode tail gas entering the flame tube using the anode tail gas intake method (1) is preferably 80-95% of the total amount of anode tail gas intake, and the amount of anode tail gas entering the flame tube using the anode tail gas intake method (2) is preferably 5-20% of the total amount of anode tail gas intake. The amount of cathode tail gas entering the flame tube using the cathode tail gas intake method (1) is preferably 65-92% of the total amount of cathode tail gas intake, and the amount of cathode tail gas entering the flame tube using the cathode tail gas intake method (2) is preferably 3-15% of the total amount of cathode tail gas intake, and the amount of cathode tail gas entering the flame tube using the cathode tail gas intake method (3) is preferably 5-20% of the total amount of cathode tail gas intake.

[0068] The cathode exhaust gas that enters the flame tube using the cathode exhaust gas intake method (1) is preferably 10-35% of the total cathode exhaust gas intake amount that enters the flame tube from the guide mixing hole, and preferably 15-50% of the total cathode exhaust gas intake amount that enters the flame tube from the mixing straight hole; and the cathode exhaust gas that enters the flame tube from the cooling inclined hole is preferably 5-30% of the total cathode exhaust gas intake amount.

[0069] The anode exhaust gas and cathode exhaust gas entering the flame tube adopt a combustion method of swirl diffusion combined with blunt body flame stabilization. After the igniter works, a diffusion combustion flame is formed in which a swirl cathode exhaust gas wraps around a swirl anode exhaust gas downstream of the combustion chamber nozzle in the flame tube. Most of the anode exhaust gas enters the flame tube in a swirl manner, and a small part of the anode exhaust gas enters the flame tube in a direct current manner, so that a flame recirculation zone can be formed downstream of the blunt body under different airflow conditions. Under the joint action of the recirculation zone formed by the swirl and the recirculation zone formed by the direct current, the stable combustion is guaranteed under various conditions. Under the starting condition, a weak airflow forms a vortex structure at the edge of the blunt body to stabilize the flame. Flame, under power generation conditions, a large flow of anode exhaust gas forms a strong recirculation zone downstream of the blunt body to stabilize the flame through swirl, combined with the design that the cathode exhaust gas enters the flame tube in multiple ways, realizes stable combustion in the combustion chamber under the conditions of complex gas composition changes, variable residual gas coefficients, and extremely low combustion calorific value, improves the stability of the combustion flame, and solves the problems of unstable combustion and uneven outlet temperature distribution caused by fuel characteristics (complex composition changes, wide residual gas coefficient changes, extremely low calorific value, etc.) in the combustion chamber of the solid oxide fuel cell system, and can achieve stable combustion of ultra-low calorific value fuels with a calorific value of 1150kJ / kg, and the outlet temperature distribution of the combustion chamber is uniform.

[0070] Unless otherwise specified or one preferred or optional technical means is a further limitation of another technical means, all preferred and optional technical means disclosed in the present invention can be arbitrarily combined to form several different technical solutions.

Claims

1. A combustion chamber nozzle of a fuel cell system, comprising an inner cylinder and an outer cylinder, wherein the outer cylinder is coaxially sleeved outside the inner cylinder, the outer diameter of the inner cylinder is smaller than the inner diameter of the outer cylinder, and the annular space between the inner cylinder and the outer cylinder constitutes a swirl cathode tail gas inlet channel, characterized in that A blunt body is coaxially arranged in the inner cylinder. The blunt body is cylindrical and has an end plate at its outlet end. The end plate is densely covered with through holes. The outer diameter of the blunt body is smaller than the inner diameter of the inner cylinder. The annular space between the blunt body and the inner cylinder constitutes a swirl anode tail gas inlet channel. The axial hole of the blunt body constitutes a DC anode tail gas inlet channel.

2. The combustion chamber nozzle of the fuel cell system according to claim 1, characterized in that The bluff body includes a first inner diameter gradually expanding section, an inner diameter constant diameter section and a second inner diameter gradually expanding section in sequence from the air inlet end to the air outlet end. The outer wall of the first inner diameter gradually expanding section is streamlined with an arc transition.

3. The combustion chamber nozzle of the fuel cell system according to claim 2, characterized in that The inner cylinder includes a constant inner diameter section and an inner diameter gradually expanding section from the air inlet end to the air outlet end, and the second inner diameter gradually expanding section of the bluff body is located in the inner diameter gradually expanding section of the inner cylinder.

4. The combustion chamber nozzle of the fuel cell system according to claim 3, characterized in that The outer cylinder includes a constant inner diameter section and a gradually expanding inner diameter section from the air inlet end to the air outlet end, and the gradually expanding inner diameter section of the inner cylinder is located inside the gradually expanding inner diameter section of the outer cylinder.

5. The combustion chamber nozzle of the fuel cell system according to claim 1, characterized in that The swirl cathode tail gas inlet passage and the swirl anode tail gas inlet passage are both provided with swirl components.

6. A combustion chamber of a fuel cell system, comprising a combustion chamber casing and a flame tube, wherein the flame tube is coaxially located in the combustion chamber casing, an anode tail gas inlet is provided on the side wall of the combustion chamber casing, a cathode tail gas inlet is provided on the head end wall or side wall of the combustion chamber casing, the head end wall of the flame tube is densely covered with end wall through holes, a plurality of side wall through holes are provided on the side wall of the flame tube, a gap is left between the head end wall of the flame tube and the head end wall of the combustion chamber casing, an anode tail gas collecting chamber connected to the anode tail gas inlet is provided in the gap, a combustion chamber nozzle is provided between the anode tail gas collecting chamber and the flame tube, characterized in that The combustion chamber nozzle adopts the combustion chamber nozzle of the fuel cell system described in any one of claims 1-5, the swirl anode exhaust gas inlet channel and the direct current anode exhaust gas inlet channel both connect the anode exhaust gas collecting chamber with the flame tube, and the swirl cathode exhaust gas inlet channel connects the internal space of the combustion chamber casing with the flame tube.

7. The combustion chamber of the fuel cell system according to claim 6, characterized in that The side wall through holes include guide and mixing holes, cooling inclined holes and mixing straight holes. The number of the guide and mixing holes is multiple and they are evenly distributed along the same radial circumference on the side wall of the flame tube. The guide and mixing holes are provided with guide flanges. The cooling inclined holes are inclined from the outside of the flame tube to the inside of the flame tube from the head end to the tail end, and the angle between them and the side wall surface of the flame tube is 25-40°. The cooling inclined holes are divided into several groups, and the number of each group of cooling inclined holes is multiple. Several groups of cooling inclined holes are evenly distributed along different radial circumferences on the side wall of the flame tube at equal intervals. The cooling inclined holes are distributed from the upstream to the downstream of the guide and mixing holes. The number of the mixing straight holes is multiple and they are evenly distributed along the same radial circumference on the side wall of the flame tube, or the mixing straight holes are divided into several groups, and the number of each group of mixing straight holes is multiple. Several groups of mixing straight holes are evenly distributed along different radial circumferences on the side wall of the flame tube at equal intervals, and the mixing straight holes are located downstream of the cooling inclined holes.

8. The combustion chamber of the fuel cell system according to claim 6, characterized in that A splash plate with a circular outer edge is coaxially provided on the head end wall side of the flame tube. The diameter of the splash plate is smaller than the inner diameter of the head of the flame tube, and a distance is left between the splash plate and the head end wall of the flame tube to form an air inlet channel for the flame tube head of the cathode tail gas. A nozzle insertion seat is provided on the splash plate, and the outlet end of the combustion chamber nozzle is inserted into the nozzle insertion seat and sealed.

9. A flame tube air intake method for a fuel cell system using a combustion chamber of a fuel cell system according to any one of claims 6 to 8, characterized in that The anode tail gas of the fuel cell stack enters the flame tube in the following anode tail gas intake method: (1) The swirl flow anode tail gas enters the flame tube from the swirl flow anode tail gas inlet passage; (2) entering the flame tube from the axial hole of the blunt body; The cathode tail gas of the fuel cell stack enters the flame tube in the following cathode tail gas intake method: (1) entering the flame tube from the side wall through holes distributed on the side wall of the flame tube; (2) entering the flame tube from the end wall through holes distributed on the end wall of the head of the flame tube; (3) the swirl cathode tail gas enters the flame tube in a swirl manner from the swirl cathode tail gas inlet passage; The cathode exhaust gas entering the flame tube in a swirl manner wraps the anode exhaust gas entering the flame tube in a swirl manner and entering the flame tube from the axial hole of the blunt body in an intake direction.

10. The flame tube air intake method of the fuel cell system according to claim 9, characterized in that The amount of anode exhaust gas entering the flame tube using the anode exhaust gas intake method (1) is 80-95% of the total amount of anode exhaust gas intake; the amount of anode exhaust gas entering the flame tube using the anode exhaust gas intake method (2) is 5-20% of the total amount of anode exhaust gas intake; the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (1) is 65-92% of the total amount of cathode exhaust gas intake; the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (2) is 3-15% of the total amount of cathode exhaust gas intake; and the amount of cathode exhaust gas entering the flame tube using the cathode exhaust gas intake method (3) is 5-20% of the total amount of cathode exhaust gas intake.

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