Fuel cell power generation system and its exhaust gas combustion device

Abstract

The present invention discloses an exhaust gas combustion device for a fuel cell power generation system. The exhaust gas combustion device (100) includes: a plurality of intake cylinders (1), each including an anode exhaust gas inlet end, an oxygen inlet end, and a flame combustion end; and a flue gas reflux housing (2), including a housing peripheral wall (201) and a flue gas reflux cavity (202) defined by the housing peripheral wall (201). In the manner of gentle combustion of oxygen and anode exhaust gas, a plurality of intake cylinders are provided on the peripheral wall of the oxygen reflux housing. Oxygen and anode exhaust gas swirl out from the intake cylinders and are mixed once to form a mixed gas. The combustion generates combustion flue gas, and the combustion flue gas flows back along the housing peripheral wall in the oxygen reflux housing to one side of other intake cylinders and is mixed with the mixed gas twice to form a gentle combustion gas. Gentle combustion can simplify the process, save energy and reduce emissions, achieve high conversion rate of exhaust gas, reduce pollutant emissions, and improve power generation efficiency and fuel utilization rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas power generation, and specifically, relates to a fuel cell power generation system and an exhaust gas combustion device thereof. Background Art

[0002] The SOFC fuel cell power generation system is an all-solid-state chemical power generation device that directly and efficiently converts the chemical energy stored in fuels and oxidants into electrical energy at medium and high temperatures in an environmentally friendly manner. It has the characteristics of high efficiency, no pollution, an all-solid-state structure, and wide adaptability to various fuel gases. In the SOFC fuel cell power generation system, after the anode gas reacts, anode exhaust gas with a high water content is formed. Since there is still a certain amount of unburned fuel in the anode exhaust gas, the anode exhaust gas needs to be treated by an exhaust gas burner.

[0003] The combustible concentration in the anode exhaust gas is too low and the water content is high, making it impossible to directly ignite the anode exhaust gas. The existing treatment of anode exhaust gas mainly adopts the methods of direct open-flame combustion or catalytic combustion. Specifically, in order to reduce the water content in the anode exhaust gas, it is first necessary to condense and dehydrate the anode exhaust gas. In this process, due to the introduction of the condensation process, the process complexity is increased, and the heat loss of the system during the condensation process is huge, reducing the thermal utilization rate.

[0004] In addition, in order to achieve the combustible conditions of the anode exhaust gas, it is often necessary to supplement a certain amount of combustible gas or combustion-supporting air. Supplementing combustible gas will inevitably reduce the overall fuel utilization rate of the fuel cell power generation system, while supplementing combustion-supporting air will introduce a large amount of impurity gas nitrogen, which not only increases the generation of acidic pollutants such as NO x etc., but also is not conducive to achieving efficient carbon dioxide enrichment. Summary of the Invention

[0005] Aiming at the above-mentioned defects or deficiencies of the prior art, the present invention provides a fuel cell power generation system and an exhaust gas combustion device thereof, which simplifies the process flow, realizes high conversion rate of exhaust gas with energy conservation and emission reduction, reduces pollutant emissions, and improves power generation efficiency and fuel utilization rate.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an exhaust gas combustion device for a fuel cell power generation system, the exhaust gas combustion device comprising:

[0007] A flue gas reflux housing, comprising a housing peripheral wall and a flue gas reflux chamber defined by the housing peripheral wall; and

[0008] A plurality of intake cylinders, each including an anode tail gas inlet end, an oxygen inlet end, and a flame combustion end, the flame combustion end being connected to the circumferential wall of the housing and communicating with the flue gas reflux chamber. The anode tail gas introduced through the anode tail gas inlet end and the oxygen entering through the oxygen inlet end swirl out from the flame combustion end to form a mixed gas, and the mixed gas burns in the flue gas reflux chamber to form combustion flue gas.

[0009] Wherein, the flame combustion end at least includes a first flame combustion end and a second flame combustion end adjacent to each other circumferentially. The combustion flue gas formed by the mixed gas on either side of the first flame combustion end and the second flame combustion end can flow back along the circumferential wall of the housing to the other side to achieve gentle combustion.

[0010] In some embodiments, the flue gas reflux housing is in a disc shape.

[0011] In some embodiments, the intake cylinders are arranged along the tangential direction of the circumferential wall of the flue gas reflux housing.

[0012] In some embodiments, the intake cylinder includes a swirl cylinder body and an internally nested anode tail gas inlet pipe. One end of the swirl cylinder body is the flame combustion end, and an oxygen inlet pipe is connected to the circumferential wall at the other end.

[0013] In some embodiments, the flame combustion end is provided with a swirl nozzle for swirling the flow of oxygen and the anode tail gas. The swirl nozzle includes:

[0014] An oxygen swirl nozzle, in a disc shape and including a central hole and a plurality of oxygen holes. The plurality of oxygen holes are arranged radially outside the central hole and are sequentially spaced apart circumferentially; and

[0015] An anode tail gas swirl nozzle, installed in the central hole and including a plurality of anode tail gas holes, the plurality of anode tail gas holes being sequentially spaced apart circumferentially.

[0016] In some embodiments, the oxygen inlet pipe is connected to a pure oxygen supply pipe or an oxygen generator.

[0017] In some embodiments, the tail gas combustion device further includes a combustion flue gas exhaust pipe for discharging the combustion flue gas. The combustion flue gas exhaust pipe is connected to the top wall of the housing of the flue gas reflux housing and communicates with the flue gas reflux chamber.

[0018] In addition, a fuel cell power generation system is also provided. The fuel cell power generation system includes a heat preservation box, and a power generation module for gas power generation and the above-mentioned tail gas combustion device are installed in the heat preservation box.

[0019] In some embodiments, the fuel cell power generation system includes an anode heat exchanger installed in the heat preservation box for heat exchange of anode gas, and an anode gas distribution pipeline connected among the power generation module, the tail gas combustion device, and the anode heat exchanger. The anode gas distribution pipeline includes:

[0020] An anode inlet gas pipeline, which extends from the gas heat exchange outlet end of the anode heat exchanger and extends into the gas inlet end of the power generation module;

[0021] An anode tail gas exhaust pipe, which extends from the anode tail gas outlet end of the power generation module and is connected to the anode tail gas inlet pipe of the tail gas combustion device;

[0022] A flue gas heat exchange inlet pipe, which extends from the flue gas exhaust pipe of the tail gas combustion device and extends into the tail gas heat exchange inlet end of the anode heat exchanger; and

[0023] A flue gas treatment pipe, which extends from the tail gas heat exchange outlet end of the anode heat exchanger.

[0024] In some embodiments, the fuel cell power generation system further includes a cathode heat exchanger for heat exchange between cathode air and cathode tail gas, and a cathode gas distribution pipeline connected between the power generation module and the cathode heat exchanger. Both the cathode heat exchanger and the cathode gas distribution pipeline are built in the heat preservation box.

[0025] In some embodiments, the cathode heat exchanger, the power generation module, the tail gas combustion device, and the anode heat exchanger are arranged in sequence from top to bottom along the height direction of the heat preservation box.

[0026] In some embodiments, both the anode heat exchanger and the cathode heat exchanger are plate-fin heat exchangers.

[0027] In the fuel cell power generation system and its tail gas combustion device of the present invention, a gentle combustion method of pure oxygen and anode tail gas is adopted. A plurality of air inlet cylinders are arranged on the peripheral wall of the oxygen return housing. The pure oxygen and the anode tail gas flow out in a swirling manner from the air inlet cylinders and are mixed once to form a mixed gas. The mixed gas burns to generate combustion flue gas. The combustion flue gas flows back along the peripheral wall of the housing in the oxygen return housing to the side of other air inlet cylinders and is mixed with the mixed gas again to form a gentle combustion gas. The tail gas combustion device of the fuel cell power generation system simplifies the process flow, realizes energy conservation and emission reduction, achieves high conversion rate of tail gas, reduces pollutant emissions, and improves power generation efficiency and fuel utilization rate.

[0028] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0030] Figure 1 is a working schematic diagram of a fuel cell power generation system according to a specific embodiment of the present invention;

[0031] Figure 2 is a three-dimensional view of an exhaust gas combustion device of a fuel cell power generation system according to a specific embodiment of the present invention;

[0032] Figure 3 and Figure 4 are both Figure 2 structural schematic diagrams from different perspectives, specifically showing the air inlet cylinder, the flue gas reflux housing, and the combustion flue gas exhaust pipe;

[0033] Figure 5 is Figure 2 an internal structural schematic diagram from different perspectives, specifically showing the air inlet cylinder, the flue gas reflux housing, and the swirl nozzle;

[0034] Figure 6 is Figure 5 a partial structural schematic diagram from different perspectives of , specifically showing the swirl cylinder body, the swirl nozzle, the oxygen holes, and the anode exhaust gas holes; and

[0035] Figure 7 is a module schematic diagram of a fuel cell power generation system according to a specific embodiment of the present invention.

[0036] Explanation of reference numerals:

[0037] 100 Exhaust gas combustion device 200 Heat preservation box

[0038] 300 Power generation module 400 Anode heat exchanger

[0039] 500 Anode gas distribution pipeline 600 Cathode heat exchanger

[0040] 700 Cathode gas distribution pipeline

[0041] 1 Air inlet cylinder

[0042] 101 Swirl cylinder body 102 Anode exhaust gas inlet pipe

[0043] 2 Flue gas reflux housing

[0044] 201 Housing peripheral wall 202 Flue gas reflux chamber

[0045] 3 Swirl nozzle

[0046] 301 Oxygen swirl nozzle 302 Anode tail gas swirl nozzle

[0047] 4 Oxygen inlet pipe 5 Oxygen holes

[0048] 6 Anode tail gas holes 7 Combustion flue gas exhaust pipe

[0049] 510 Anode inlet pipeline 520 Anode tail gas exhaust pipe

[0050] 530 Flue gas heat exchange inlet pipe 540 Flue gas treatment pipe

[0051] A Anode fuel gas B Oxygen

[0052] C Cathode air Detailed implementation manners

[0053] The following will describe in detail the detailed implementation manners of the present invention with reference to the accompanying drawings. It should be understood that the detailed implementation manners described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0054] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0055] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are usually in the direction shown in the accompanying drawings or in terms of the vertical, perpendicular or gravitational direction for describing the relative positional relationship of each component.

[0056] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0057] The present invention first discloses a fuel cell power generation system and its tail gas combustion device. The power generation system includes anode gas and cathode gas. Among them, the anode gas is fuel gas, which can be syngas or natural gas, and is not specifically limited herein. The cathode gas is air. The following will elaborate on the tail gas combustion device and other functional parts of the fuel cell power generation system in detail.

[0058] The present invention aims to solve the problems of cumbersome anode tail gas treatment process, low fuel utilization rate and high pollutants in the fuel cell power generation system. In the existing fuel cell power generation system, the combustible concentration of the anode tail gas is too low and the water content is high, making the anode tail gas unable to be directly ignited. It is necessary to perform process treatments such as dehydration on the anode tail gas and increase the content of fuel gas or combustion-supporting gas to reach the tail gas combustion conditions, which violates the concept of environmentally friendly processes and at the same time restricts the fuel utilization rate of the fuel cell power generation system. Therefore, how to solve the treatment problem of the anode tail gas is a problem worthy of attention, to simplify the process flow, save energy and reduce emissions, and improve the fuel utilization rate as much as possible on the basis of environmentally friendly processes.

[0059] To this end, the present invention provides an exhaust gas combustion device for a fuel cell power generation system. As Figures 2 to 6 shown, the exhaust gas combustion device 100 includes: a plurality of intake cylinders 1 and a flue gas reflux housing 2;

[0060] The flue gas reflux housing 2 includes a housing peripheral wall 201 and a flue gas reflux chamber 202 defined by the surrounding of the housing peripheral wall 201; and

[0061] The plurality of intake cylinders 1 each include an anode exhaust gas inlet end, an oxygen inlet end, and a flame combustion end. The flame combustion end is connected to the housing peripheral wall 201 and communicates with the flue gas reflux chamber 202. The anode exhaust gas introduced through the anode exhaust gas inlet end and the oxygen entering through the oxygen inlet end swirl out from the flame combustion end to form a mixed gas, and the mixed gas burns in the flue gas reflux chamber 202 to form combustion flue gas;

[0062] Wherein, the flame combustion end at least includes a circumferentially adjacent first flame combustion end and second flame combustion end. The combustion flue gas formed by the mixed gas on either side of the first flame combustion end and the second flame combustion end can flow back along the housing peripheral wall 201 to the other side to achieve gentle combustion.

[0063] First of all, it should be noted that in the exhaust gas combustion device 100, a highly efficient and clean combustion method that can self-ignite without ignition is formed, that is, gentle combustion. Gentle combustion can occur under conditions of extremely low calorific value, ultra-high excess air, and rich in a large amount of water vapor. Its reaction conditions are: T in >T si >ΔT, that is, the temperature of the combustible in the gentle combustion gas > the self-ignition temperature of the combustible in the gentle combustion gas > the temperature rise of the combustion reaction.

[0064] Based on the reaction conditions of mild combustion, the structure of the tail gas combustion device 100 is designed. Specifically, the intake cylinder 1 can be connected to the flue gas reflux housing 2 so that the flame combustion end communicates with the flue gas reflux chamber 202. There are at least two intake cylinders 1 in the tail gas combustion device 100. Taking two intake cylinders 1 as an example. In the tail gas combustion device 100, the fuel gas is the directly discharged anode tail gas, that is, it has not undergone dehydration treatment, which simplifies the process and reduces heat loss. The combustion-supporting gas is pure oxygen, which avoids introducing a large amount of nitrogen and reduces the generation of combustion pollutants. At the same time, it is convenient for efficient carbon dioxide enrichment. In the tail gas combustion device 100, the anode tail gas and oxygen swirl out from the flame combustion end and form a mixed gas. This mixed gas can burn in the flue gas reflux chamber 202 and near the flame combustion end to form initial combustion flue gas, and the combustion flue gas flows back along the housing wall 201 of the flue gas reflux housing 2. At this time, in the flue gas reflux chamber 202, the combustion flue gas on one side of the first flame combustion end can flow back along the housing wall 201 to the side of the second flame combustion end, and the combustion flue gas on one side of the second flame combustion end can flow back along the housing wall 201 to the side of the first flame combustion end. The high-temperature combustion flue gas can mix with the mixed gas near the flame combustion end in the flue gas reflux chamber 202 to form high-temperature mild combustion gas. It should be noted that to ensure that the anode tail gas and oxygen can burn and form initial combustion flue gas, the initial fuel utilization rate of the anode fuel gas and the flow rate of oxygen can be controlled to ensure the combustion conditions, and then the working condition of the fuel cell power generation system can be further adjusted after mild combustion is formed.

[0065] Since most of the energy of the anode gas has been consumed after the electrochemical reaction, the content of combustibles in the anode tail gas is low, that is, the temperature rise of the combustion reaction is very low. At the same time, since the high-temperature combustion flue gas contains a large amount of discrete free radicals such as H, OH or CH, the activation energy of the combustion reaction can be greatly reduced, thereby reducing the ignition point temperature, getting rid of the limitations of low calorific value and high water content on stable combustion. Therefore, the mild combustion gas can meet the conditions that the temperature of the combustibles in the mild combustion gas > the spontaneous ignition temperature of the combustibles in the mild combustion gas > the temperature rise condition of the combustion reaction, and realize the mild combustion of the anode tail gas.

[0066] Comparatively, most of the tail gas combustion devices of existing power generation systems adopt open-flame direct combustion or catalytic combustion. For example, in US Patent No. US 009190673B2, open-flame direct combustion is disclosed. After the anode tail gas with high water content is condensed and dehydrated and reaches the flammable condition, normal-temperature air is used as the combustion-supporting agent for open-flame combustion. US20090208784A1 discloses catalytic combustion. In this patent, the unheated cathode outlet air is used as the combustion-supporting agent. The anode tail gas with high moisture and low calorific value is first dehydrated, and then a certain amount of pure natural gas is supplemented to reach the flammable condition. Under the condition that the reaction temperature is sufficient, catalyst is used for non-ignition catalytic combustion. Among them, the condensation dehydration process not only increases the complexity of the process, but also causes a large amount of heat loss in the system, reducing the thermal utilization rate. At the same time, supplementing gas causes waste of energy, reduces the thermal utilization rate of raw materials, and supplementing air introduces a large amount of impurity gas nitrogen, which is not conducive to the further enrichment of carbon dioxide. For open-flame direct combustion, ignition is required during startup, which will bring dynamic impacts such as deflagration and instantaneous pressure increase, and there are certain safety hazards, and local high temperature brings NO x and other acidic pollutant emissions. For catalytic combustion, it is overly dependent on the efficiency and performance of the catalyst, and it is difficult to guarantee the service life of the catalyst under high temperature conditions.

[0067] Therefore, in the present invention, the above-mentioned mild combustion is adopted. The temperature of the mild combustion gas is higher than the auto-ignition temperature. Therefore, the mild combustion gas can achieve auto-ignition without the ignition process, simplifying the process flow; the oxygen content can be about one-seventh of the anode tail gas, and the equivalence ratio is relatively large, with almost no excess oxygen. Due to being diluted by the combustion flue gas, the oxygen content in the mild combustion gas is extremely low, reducing the pollutant generation rate. At the same time, the combustion flame has a discrete and uniform temperature or even no open flame, and there is no local high temperature point, protecting the equipment from the influence of local high temperature. At the same time, since the value of NO X rises exponentially with the increase of temperature, therefore, controlling the overall and local temperatures and avoiding the occurrence of high temperature points can greatly reduce the NO X emissions and effectively control the NO x acidic pollutant emissions; in addition, the anode tail gas and oxygen are fully mixed through the air inlet cylinder 1, and the combustion flue gas and the mixed gas are fully mixed through the flue gas reflux housing 2. The reactants are evenly mixed, and the reaction efficiency of the mild combustion is extremely high, realizing the efficient conversion of CO, facilitating the further enrichment of carbon dioxide, and reducing pollutant emissions.

[0068] In order to form a reflux of the combustion flue gas in the flue gas reflux housing 2, it is necessary for the circumferential wall 201 of the housing to guide the combustion flue gas. Therefore, the flue gas reflux housing 2 can be a disk-like structure. In one embodiment, such as Figure 2 and Figure 4As shown, the flue gas reflux housing 2 is in a disc shape. The arc-shaped housing peripheral wall 201 can well guide the combustion flue gas, ensuring the gentle combustion of the anode tail gas.

[0069] To form the guiding effect of the combustion flue gas treatment housing peripheral wall 201 for the reflux, it is also necessary to control the angular direction of the combustion flue gas entering the flue gas reflux housing 2. In one embodiment, as Figure 4 and Figure 5 shown, the intake cylinder 1 is arranged along the tangential direction of the peripheral wall of the flue gas reflux housing 2, so that the mixed gas can enter the flue gas reflux cavity 202 along the tangential direction of the housing peripheral wall 201, further enabling the combustion flue gas generated on one side of the near first flame combustion end and the second flame combustion end to flow back to the other side along the housing peripheral wall 201, ensuring the gentle combustion of the anode tail gas.

[0070] The temperature of the anode tail gas is about 700 - 800 °C, the flow rate of the anode tail gas is about 10 times that of oxygen, and the equivalence ratio is close to 1. Therefore, it is difficult to mix the two. To improve the mixing effect of the two, the intake cylinder 1 is optimized. In one embodiment, as Figure 5 shown, the intake cylinder 1 may include a swirl cylinder body 101 and an internally nested anode tail gas inlet pipe 102. One end of the swirl cylinder body 101 is the flame combustion end, and an oxygen inlet pipe 4 is connected to the peripheral wall at the other end. Among them, the anode tail gas inlet pipe 102 is used to introduce the anode tail gas, and the oxygen inlet pipe 4 is used to introduce oxygen. The two flow out swirlingly from the flame combustion end and converge to form a mixed gas, and the mixed gas flows and burns along the gas flow direction to form combustion flue gas.

[0071] Furthermore, in one embodiment, as Figure 6 shown, a swirl nozzle 3 for swirling the oxygen and the anode tail gas is provided at the flame combustion end. The swirl nozzle 3 includes: an oxygen swirl nozzle 301, which is in a disc shape and includes a central hole and a plurality of oxygen holes 5. The plurality of oxygen holes 5 are arranged radially outside the central hole and are sequentially spaced along the circumferential direction; and, an anode tail gas swirl nozzle 302, which is installed in the central hole and includes a plurality of anode tail gas holes 6. The plurality of anode tail gas holes 6 are sequentially spaced along the circumferential direction. It can be understood that the oxygen and the anode tail gas rely on the oxygen holes 5 and the anode tail gas holes 6 of the swirl nozzle 3 for direction adjustment. Among them, the holes of the oxygen holes 5 are oxygen swirl holes with the hole axes inclined towards the same circumferential direction, and the holes of the anode tail gas holes 6 are anode tail gas swirl holes with the hole axes inclined towards the same circumferential direction, so that the oxygen and the anode tail gas flow and mix along the radial swirl direction of the swirl nozzle 3, realizing the rapid mixing of the oxygen and the anode tail gas and ensuring the uniform mixing of the two.

[0072] For the source of the combustion-supporting gas pure oxygen, in one embodiment, the oxygen inlet pipe 4 can be connected to a pure oxygen supply pipe or to an oxygen generator. It can be understood that as long as pure oxygen can be introduced into the oxygen inlet pipe 4, specific limitations are not made here.

[0073] After the generated combustion flue gas is refluxed and gently combusted with the anode tail gas and oxygen, as the amount of the combustion flue gas gradually increases, the excessive combustion flue gas needs to be discharged from the flue gas reflux housing 2. Therefore, in one embodiment, as Figure 3 and Figure 4 shown, the tail gas combustion device 100 may further include a combustion flue gas exhaust pipe 7 for discharging the combustion flue gas. The combustion flue gas exhaust pipe 7 is connected to the top wall of the housing of the flue gas reflux housing 2 and communicates with the flue gas reflux chamber 202. The excessive combustion flue gas can be discharged along the flue gas exhaust pipe 7 at the top. Among them, the combustion flue gas exhaust pipe 7 may be located at the radial center of the top wall of the housing and be at the same distance from each intake cylinder 1 to ensure the stable reflux of the combustion flue gas in the oxygen reflux housing 2 and stable gentle combustion.

[0074] In addition, in the existing open-flame combustion, the burner is placed outside the hot box, and the heat generated by the combustion is not fully utilized by the system module. Therefore, the present invention further provides a fuel cell power generation system, which includes a heat preservation box 200. Inside the heat preservation box 200, a power generation module 300 for gas power generation and the above-mentioned tail gas combustion device 100 are installed. Among them, the tail gas combustion device 100 is placed inside the heat preservation box 200, so that the heat generated by the tail gas combustion can be utilized by other heat elements in the heat preservation box 200, further improving the utilization rate of the fuel.

[0075] Furthermore, for the fuel cell power generation system, the tail gas combustion device 100 uses the directly discharged anode tail gas, as Figure 1 and Figure 7As shown, in one embodiment, the fuel cell power generation system includes an anode heat exchanger 400 installed in the heat preservation box 200 for heat exchange of anode gas, and an anode gas distribution pipeline 500 connected between the power generation module 300, the tail gas combustion device 100 and the anode heat exchanger 400. The anode gas distribution pipeline 500 includes: an anode inlet gas pipeline 510, which extends from the gas heat exchange outlet end of the anode heat exchanger 400 and extends into the gas inlet end of the power generation module 300; an anode tail gas exhaust pipe 520, which extends from the anode tail gas outlet end of the power generation module 300 and is connected to the anode tail gas inlet pipe 102 of the tail gas combustion device 100; a flue gas heat exchange inlet pipe 530, which extends from the flue gas exhaust pipe 7 of the tail gas combustion device 100 and extends into the tail gas heat exchange inlet end of the anode heat exchanger 400; and a flue gas treatment pipe 540, which extends from the tail gas heat exchange outlet end of the anode heat exchanger 400. Among them, after the tail gas combustion device 100 burns the anode tail gas, the combustion flue gas exchanges heat with the anode inlet gas. It can be understood that the heat generated by the power generation module 300 and the tail gas combustion device 100 acts together on the anode inlet gas, achieving the maximum utilization of heat.

[0076] In some embodiments, the fuel cell power generation system further includes a cathode heat exchanger 600 for heat exchange between cathode air and cathode tail gas, and a cathode gas distribution pipeline 700 connected between the power generation module 300 and the cathode heat exchanger 600. Both the cathode heat exchanger 600 and the cathode gas distribution pipeline 700 are built in the heat preservation box 200.

[0077] In addition, the working principle of this fuel cell power generation system is as Figure 1 shown. Specifically, the anode gas A as the anode gas passes through the anode heat exchanger 400 and then enters the power generation module 300 along the anode inlet gas pipeline 510, and the cathode air C as the cathode gas enters the power generation module 300 after passing through the cathode heat exchanger 600. Inside the power generation module, the anode gas A and the cathode air C undergo an electrochemical reaction. After the reaction, anode tail gas is generated at the anode and cathode tail gas is generated at the cathode. Among them, the anode tail gas is discharged along the anode tail gas exhaust pipe 520 and enters the anode tail gas inlet pipe 102 of the tail gas combustion device 100, where it swirls and flows out, mixes with the oxygen B entering along the anode inlet pipe 4, and forms a gentle combustion. The high-temperature combustion flue gas after combustion is discharged along the flue gas heat exchange inlet pipe 530 and enters the anode heat exchanger 400 to exchange heat with the anode gas A, and then is discharged along the flue gas treatment pipe 540 for subsequent carbon dioxide enrichment. The cathode tail gas flows along the cathode gas distribution pipeline 700 and enters the cathode heat exchanger 600 to exchange heat with the cathode air C, and then is discharged along the cathode gas distribution pipeline 700.

[0078] Among them, in one embodiment, the cathode heat exchanger 600, the power generation module 300, the tail gas combustion device 100, and the anode heat exchanger 400 are arranged in sequence from top to bottom along the height direction of the heat preservation box 200. Among them, the structure of the tail gas combustion device 100 is simple, and it is disk-shaped with a small volume, which is easy to integrate. Each high-temperature component is concentrated in the heat preservation box 200, and a one-word arrangement from top to bottom can be adopted, making the structure more compact and improving the overall integration degree of the power generation system. A nearly thermally isolated system is formed to avoid heat dissipation to the external environment and improve the thermal utilization rate.

[0079] In some embodiments, both the anode heat exchanger 400 and the cathode heat exchanger 600 are plate-fin heat exchangers. The anode heat exchanger 400 and the cathode heat exchanger 600 can adopt plate-fin heat exchangers with a high degree of process maturity, a more compact structure, and a higher heat transfer efficiency. This heat exchanger is of a square structure, with a relatively small volume and a small specific surface area. Under the premise of controlling costs and ensuring stable operation, it has less heat loss and high thermal efficiency. In addition, during the electrochemical reaction process, the cathode gas flow rate is much larger than the anode gas flow rate. Therefore, the number of cathode heat exchangers 600 can be more than the number of anode heat exchangers 400 to achieve efficient heat transfer, and no specific limitation is made here.

[0080] It should be particularly noted that the other components and functions of the fuel cell power generation system according to the embodiments of the present invention are known to those of ordinary skill in the art. To reduce redundancy, no further description is given here.

[0081] The present invention conducts a detection test under the conditions of a typical 20KW-class IGFC fuel cell power generation system, and the specific working condition parameters are as follows:

[0082]

[0083] Among them, the anode tail gas flow rate is 0.566 kmol / h, and the temperature is 800 °C; the oxygen flow rate is 0.0284 kmol / h, and the temperature is 25 °C. The flow rates differ by nearly 20 times. Under the conditions of high water content and low content of combustible components in the anode tail gas, the two are swirled and mixed in the intake cylinder 1 and gently combusted.

[0084] According to the above working conditions, a fuel cell power generation system with gentle combustion is compared with a fuel cell power generation system with conventional diffusion combustion (the tail gas is cooled and dehydrated conventionally), and the CFD calculation results are shown in the following table:

[0085]

[0086] The results show that the fuel cell power generation system of the present invention can form stable gentle combustion without dehydration and significantly reduce CO and NO xEmissions. In a fuel cell power generation system using conventional diffusion combustion, diffusion open-flame combustion cannot burn stably without dehydration, and the pollutant emissions after cooling are significantly higher than those of gentle combustion.

[0087] In summary, the tail gas combustion device of the fuel cell power generation system of the present invention adopts the method of gentle combustion of pure oxygen and anode tail gas. A plurality of air inlet cylinders are arranged on the peripheral wall of the oxygen return housing. The pure oxygen and the anode tail gas swirl out from the air inlet cylinders and are mixed once to form a mixed gas. The mixed gas burns to generate combustion flue gas. The combustion flue gas flows back along the peripheral wall of the oxygen return housing to the side of other air inlet cylinders and is mixed with the mixed gas again to form a gentle combustion gas. The gentle combustion gas can achieve self-ignition without an ignition process, simplifying the process flow; the oxygen flow rate is low, making the oxygen content in the gentle combustion gas extremely low, the reaction is relatively slow, the flame dispersion temperature is uniform or even there is no open flame, there is no local high temperature point, protecting the equipment from the influence of local high temperature, and greatly reducing the NO X emissions; in addition, the anode tail gas and oxygen swirl out and are fully mixed through the air inlet cylinder 1, and the combustion flue gas and the mixed gas are fully mixed through the flue gas return housing 2. The reactants are evenly mixed, and the reaction efficiency of gentle combustion is extremely high, realizing the efficient conversion of CO, facilitating the further enrichment of carbon dioxide, and reducing pollutant emissions.

[0088] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, such as simple changes to the number, diameter of the air inlet cylinders, and the shape of the flue gas return housing. These simple modifications all fall within the protection scope of the present invention.

[0089] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any suitable way without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0090] In addition, any combination can be made between different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. An exhaust gas combustion device for a fuel cell power generation system, characterized in that, The tail gas combustion device (100) includes: A flue gas reflux housing (2), including a housing peripheral wall (201) and a flue gas reflux chamber (202) defined by the surrounding of the housing peripheral wall (201), and the flue gas reflux housing (2) is in a disc shape; and A plurality of intake cylinders (1), each including an anode tail gas inlet end, an oxygen inlet end, and a flame combustion end. The flame combustion end is connected to the housing peripheral wall (201) and communicates with the flue gas reflux chamber (202). The anode tail gas introduced from the anode tail gas inlet end and the oxygen entering from the oxygen inlet end swirl out from the flame combustion end to form a mixed gas. The mixed gas burns in the flue gas reflux chamber (202) to form combustion flue gas, and the intake cylinders (1) are arranged along the tangential direction of the peripheral wall of the flue gas reflux housing (2); Wherein, the flame combustion end at least includes a circumferentially adjacent first flame combustion end and second flame combustion end. The combustion flue gas formed by the mixed gas on any side of the first flame combustion end and the second flame combustion end can flow back along the housing peripheral wall (201) to the other side to achieve gentle combustion. The tail gas combustion device (100) further includes a combustion flue gas exhaust pipe (7) for discharging the combustion flue gas. The combustion flue gas exhaust pipe (7) is connected to the top wall of the housing of the flue gas reflux housing (2) and communicates with the flue gas reflux chamber (202).

2. The exhaust gas combustion device of the fuel cell power generation system according to claim 1, wherein The intake cylinder (1) includes a swirl cylinder body (101) and an internally nested anode tail gas inlet pipe (102). One end of the swirl cylinder body (101) is the flame combustion end, and an oxygen inlet pipe (4) is connected to the peripheral wall at the other end.

3. The tail gas combustion device of the fuel cell power generation system according to claim 2, characterized in that, The flame combustion end is provided with a swirl nozzle (3) for swirling the flow of the oxygen and the anode tail gas. The swirl nozzle (3) includes: An oxygen swirl nozzle (301), in a disc shape and including a central hole and a plurality of oxygen holes (5). The plurality of oxygen holes (5) are arranged on the radial outside of the central hole and are sequentially spaced apart in the circumferential direction; and An anode tail gas swirl nozzle (302), embedded in the central hole and including a plurality of anode tail gas holes (6). The plurality of anode tail gas holes (6) are sequentially spaced apart in the circumferential direction.

4. The exhaust gas combustion device of the fuel cell power generation system according to claim 2, characterized in that, The oxygen inlet pipe (4) is connected to a pure oxygen supply pipe or an oxygen generator.

5. A fuel cell power generation system, characterized in that, The fuel cell power generation system includes a heat preservation box (200). A power generation module (300) for gas power generation and the tail gas combustion device (100) according to any one of claims 1 to 4 are installed in the heat preservation box (200).

6. The fuel cell power generation system according to claim 5, characterized in that, The fuel cell power generation system includes an anode heat exchanger (400) installed in the heat preservation box (200) for heat exchange of anode gas, and an anode gas distribution pipeline (500) connected between the power generation module (300), the tail gas combustion device (100), and the anode heat exchanger (400). The anode gas distribution pipeline (500) includes: An anode inlet gas pipeline (510), extending out from the gas heat exchange outlet end of the anode heat exchanger (400) and extending into the gas inlet end of the power generation module (300); An anode exhaust gas pipe (520) extends from the anode exhaust gas outlet end of the power generation module (300) and is connected to the anode exhaust gas inlet pipe (102) of the exhaust gas combustion device (100); A flue gas heat exchange inlet pipe (530) extends from the flue gas exhaust pipe (7) of the exhaust gas combustion device (100) and extends into the exhaust gas heat exchange inlet end of the anode heat exchanger (400); and A flue gas treatment pipe (540) extends from the exhaust gas heat exchange outlet end of the anode heat exchanger (400).

7. The fuel cell power generation system according to claim 6, wherein The fuel cell power generation system further includes a cathode heat exchanger (600) for heat exchange between cathode air and cathode exhaust gas and a cathode gas distribution pipe (700) connected between the power generation module (300) and the cathode heat exchanger (600), and both the cathode heat exchanger (600) and the cathode gas distribution pipe (700) are built in the heat preservation box (200).

8. The fuel cell power generation system according to claim 7, characterized in that, The cathode heat exchanger (600), the power generation module (300), the exhaust gas combustion device (100) and the anode heat exchanger (400) are arranged in sequence from top to bottom along the height direction of the heat preservation box (200).

9. The fuel cell power generation system according to claim 7, characterized in that, Both the anode heat exchanger (400) and the cathode heat exchanger (600) are plate fin heat exchangers.

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