Fast heating fuel cell system and control method

Abstract

The invention relates to a fast heating fuel cell system and a control method, in the fuel cell system, air is divided into three paths after being pressurized by a fan, one path of air enters a stack cathode after absorbing heat from a combustor through an air preheater, and the other path of air directly enters a stack for adjusting the inlet temperature of the stack cathode; the other path absorbs secondary waste heat of the anode tail gas through an air cooler, and enters a stack cathode after being secondarily preheated by an air preheater; the cathode tail gas is heated by a combustor, then subjected to primary heat release by an air preheater and subjected to secondary heat release by CPOx; fuel is fed into CPOx through a circulating pump to be mixed with gas from an air preheater for a catalytic oxidation reaction, and after the reaction, primary waste heat of anode tail gas is absorbed through an anode tail gas cooler, and then the fuel enters an electric pile fuel side; anode tail gas is divided into two paths after primary heat release through the anode tail gas cooler, one path enters the combustor to be heated, and the other path returns to the circulating pump after secondary heat release through the air cooler.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a fuel cell system and control method for rapid heating. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Medium- and high-temperature fuel cell systems require preheating of both air and fuel before feeding them into the stack. A conventional approach involves using a burner to generate heat, with air and fuel exchanging heat through separate air and fuel preheaters. Depending on whether the heat source for the fuel preheater originates from the air or fuel side, management systems are categorized into air-based thermal management systems and co-current thermal management systems. Co-current thermal management systems effectively avoid high-temperature cross-heat exchange within the fuel cell system, facilitating piping layout and improving system safety and reliability. However, they suffer from a slow initial heating rate. In traditional solutions, the air side can be rapidly heated via the burner, but the fuel side becomes a bottleneck due to its high thermal inertia (limited by the stack heating rate and air cooler). Fuel-side heating relies on stack temperature conduction, causing a lag in anode exhaust gas cooler heating, which restricts system startup speed, resulting in a slow heating rate. Summary of the Invention

[0004] To address the technical problems mentioned above, this invention provides a fuel cell system and control method for rapid heating. The CPOx (catalytic partial oxidation reformer) is placed in the flue gas, and the flue gas generated by the burner is used to preheat the CPOx to reduce start-up energy consumption. This allows the CPOx to directly heat the circulating fuel stream through an exothermic reaction, thereby increasing the heating rate of the anode tail gas cooler.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A first aspect of the present invention provides a rapidly heating fuel cell system, comprising a cathode and an anode, wherein the cathode is on the air side and the anode is on the fuel side. After being pressurized by a fan, the air is divided into three paths. One path absorbs heat from the burner through an air preheater before entering the cathode of the fuel cell stack. Another path enters the fuel cell stack directly to regulate the inlet temperature of the cathode. The third path absorbs secondary waste heat from the anode exhaust gas through an air cooler, is preheated a second time by the air preheater, and then enters the cathode of the fuel cell stack. The cathode exhaust gas is heated by the burner, then releases heat once through the air preheater, and then releases heat a second time through CPOx to provide the heat required for the CPOx reaction. Fuel is pumped into the fuel-side channel via a circulating pump and mixed with air remaining in the fuel side channel to undergo a catalytic oxidation reaction. The anode exhaust gas cooler absorbs the heat released by the CPOx through the circulating gas and then enters the fuel side of the fuel stack. The anode exhaust gas is divided into two paths after releasing heat once in the anode exhaust gas cooler. One path enters the burner to undergo a chemical reaction and heating, while the other path returns to the circulating pump after releasing heat a second time in the air cooler.

[0006] Furthermore, the air is pressurized by the fan and divided into three streams, each with its own flow rate controlled by a corresponding valve. Specifically: The amount of air entering the air preheater is adjusted by changing the opening of valve A, and the amount of air entering the fuel cell cathode is adjusted by changing the opening of valve B, thereby indirectly controlling the temperature at the inlet side of the fuel cell cathode. The amount of air entering the air cooler to absorb the secondary waste heat of the anode tail gas is adjusted by changing the opening degree of valve C.

[0007] Furthermore, after being heated by the burner, the cathode exhaust gas passes sequentially through the air preheater and CPOx. The air preheater releases the heat of the combustion exhaust gas into the air entering the fuel cell cathode, and the CPOx further releases the heat of the combustion exhaust gas into the fuel entering the fuel cell anode. The combustion exhaust gas, after secondary heat release, is then discharged to a designated area.

[0008] Furthermore, the fuel is stored in fuel tanks, and the fuel in the fuel tanks is fed into the burner and the circulation pump. The circulation pump generates the circulation power of the fuel, so that the fuel passes through the CPOx and the anode exhaust gas cooler in sequence before entering the anode of the fuel stack.

[0009] Furthermore, CPOx mixes fuel with burner exhaust gas that has been heated by an air preheater, and through catalytic oxidation, the fuel undergoes catalytic combustion under oxygen-rich conditions for rapid temperature rise during startup; under oxygen-deficient conditions, partial oxidation reforming is carried out to generate hydrogen-rich reformed gas for use in the power reactor, while maintaining heat release.

[0010] Furthermore, after the anode exhaust gas releases heat through the anode exhaust gas cooler, one path leads to the burner for heating, while the other path passes through the air cooler to transfer preheated heat to the air before returning to the circulation pump.

[0011] A second aspect of the present invention provides a control method for a rapidly heating fuel cell system, comprising the following steps: Upon startup, the burner ignites and heats up, and the circulation loops of the cathode and anode begin to heat up; During fuel purging and heating to the set temperature, fuel is gradually introduced within the lower explosive limit of the fuel. The fuel reacts with air in CPOx to form a mixture of nitrogen, carbon dioxide and water vapor, which further heats the fuel cell stack. During normal operation, once the operating temperature is reached, fuel is continuously supplied, and the oxygen-to-carbon ratio is maintained within the set range by adjusting the flow rate of the circulating pump.

[0012] Furthermore, the startup process involves: fuel being introduced into the burner for ignition and heating; the resulting high-temperature flue gas sequentially heats the air preheater and CPOx to raise the stack temperature; the fluids on the air and fuel sides of the stack exchange heat within the stack; and the preheated anode exhaust gas exchanges heat with the anode intake gas through the anode exhaust gas cooler, further raising the stack temperature.

[0013] Furthermore, fuel purging specifically involves introducing fuel in stages when the fuel stack reaches the set temperature, within the lower explosive limit of the fuel. The fuel and air undergo catalytic combustion and partial oxidation reforming reactions in CPOx, converting oxygen in the air into carbon dioxide and water vapor, thereby raising the temperature of the anode exhaust gas cooler.

[0014] Furthermore, normal operation specifically involves: after the fuel cell stack reaches its operating temperature, fuel is continuously supplied, and the flow rate of the circulating pump is adjusted according to the load current to maintain the oxygen-carbon ratio on the fuel side within a set range.

[0015] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects: 1. In traditional methods, while co-current thermal management simplifies piping layout and avoids cross-heat exchange, fuel-side heating relies on the fuel cell stack, resulting in slow start-up speed. This solution embeds the CPOx (catalytic partial oxidation reformer) into the fuel cycle loop, utilizing its exothermic reaction (catalytic combustion / partial oxidation) to directly heat the fuel stream, breaking the rate limitation of heat transfer from the fuel cell stack. Simultaneously, the CPOx is placed in the flue gas, using the combustor's flue gas as a heat source to preheat the catalyst, reducing start-up energy consumption.

[0016] 2. Traditional fuel purging methods pose safety hazards. Low-temperature purging causes fuel decomposition and carbon buildup, while high-temperature purging can easily lead to detonation when fuel mixes with air. This solution introduces fuel in stages. Under CPOx catalytic combustion mode, oxygen is gradually converted into an inert mixture of nitrogen, carbon dioxide, and water vapor before being introduced into the fuel, thus preventing detonation. During normal operation, CPOx functions primarily as a reformer (reforming the fuel), dynamically adjusting the oxygen-to-carbon ratio, and replenishing the anode side with oxygen ions through the fuel cell stack to prevent carbon buildup.

[0017] 3. Traditional methods require additional high-temperature heat exchangers or purge gases (such as N2 or steam), increasing costs and potential points of failure. This solution introduces CPOx to simultaneously perform exothermic, deoxygenation, and reforming functions, integrating multiple functions and eliminating the need for a separate purge system. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a schematic diagram of the structure of a fuel cell system provided in one or more embodiments of the present invention; Figure 2 This is a schematic diagram of the process of forming and calculating fuel input multiple times, provided by one or more embodiments of the present invention.

[0020] In the diagram: 1. Burner, 2. Fuel stack, 3. Air preheater, 4. Anode exhaust gas cooler, 5. CPOx, 6. Air cooler, 7. Circulating pump, 8. Fuel tank, 9. Fan, 10. Valve A, 11. Valve B, 12. Valve C. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the scope of exemplary embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] As described in the background section, the initial heating rate of a medium- and high-temperature fuel cell system under co-current thermal management mode is slow. In traditional solutions, the air side can be heated quickly through the burner, but the fuel side becomes a bottleneck due to its large thermal inertia (limited by the stack heating rate and air cooler). Furthermore, the heating of the fuel side depends on the stack temperature conduction, which leads to a lag in the heating of the anode exhaust gas cooler and restricts the system start-up speed.

[0025] The key factor limiting the system's heating rate lies in the heating rate of the gas-side anode exhaust gas cooler, while the air-side air preheater can rapidly heat the system via the burner. The highest temperature point on the fuel side is at the fuel cell stack, and the stack's heating rate limits the anode exhaust gas cooler's heating rate. The fuel-side hot components have no additional heat source besides the fuel cell stack. Furthermore, the air cooler at the circulating pump inlet effectively prevents overheating at the pump inlet, which also limits the anode exhaust gas cooler's heating rate. Therefore, supplementing the heat supply between the circulating pump outlet and the anode exhaust gas cooler can effectively improve the anode exhaust gas cooler's heating rate.

[0026] The commonly used approach is to add a heat exchanger between the circulating pump and the anode exhaust gas cooler. The heat source for the heat exchanger is the flue gas that exchanges heat with the air preheater, and the architecture is an air thermal management scheme. Although this approach can effectively increase the heating rate during startup and increase the inlet temperature of the fuel side of the stack in steady state, adding a heat exchanger will significantly increase the system cost and there is a certain safety risk due to the high-temperature cross-heat exchange between the flue gas and the fuel.

[0027] Therefore, the following embodiments provide a fuel cell system and control method for rapid heating. The CPOx (partial oxidation reformer) is placed in the flue gas, and the flue gas preheats the CPOx to its operating temperature. This allows the purged fuel to consume the heat generated by the air on the fuel side within the CPOx, thereby increasing the heating rate of the anode tail gas preheater. Although the CPOx is located in the flue gas, resulting in cross-heat exchange between the fuel and air, the CPOx has low heat recovery requirements. It only utilizes the flue gas to start the reaction and recover a small amount of heat. Therefore, the CPOx can be installed within a seamless steel pipe using a cordierite support or a metal support with catalytic effects, resulting in relatively low cost and no leakage risk.

[0028] CPOx is a catalytic partial oxidation reformer that uses precious metals such as platinum and palladium as catalyst carriers. When the air-fuel ratio is in an oxygen-rich state, a catalytic combustion reaction (exothermic reaction) occurs. When the air-fuel ratio is in an oxygen-deficient state, a partial oxidation reforming reaction (exothermic reaction) occurs. When only fuel remains in the pipeline (oxygen-free environment), it only serves as a fuel delivery pipeline and no catalytic reaction occurs. Therefore, there is no problem of a large heat surplus on the gas side.

[0029] Furthermore, during low-temperature purging, fuel may decompose and deposit carbon, while during high-temperature purging, the mixture of fuel and air is prone to deflagration. It is necessary to avoid carbon deposit problems caused by an imbalance in the oxygen-carbon ratio on the fuel side (especially during the start-up phase). CPOx autocatalytic combustion and partial oxidation reforming can purge the gas-side pipeline, reducing the risk of deflagration when fuel comes into contact with air under high-temperature conditions.

[0030] Example 1: A rapidly heating fuel cell system includes a cathode and an anode, with the cathode on the air side and the anode on the fuel side. After being pressurized by a fan, the air is divided into three paths. One path absorbs heat from the burner through an air preheater before entering the cathode of the fuel cell stack. Another path enters the fuel cell stack directly to regulate the inlet temperature of the cathode. The third path absorbs secondary waste heat from the anode exhaust gas through an air cooler, is preheated a second time by the air preheater, and then enters the cathode of the fuel cell stack. The cathode exhaust gas is heated by the burner, then releases heat once through the air preheater, and then releases heat a second time through CPOx to provide the heat required for the CPOx reaction. Fuel is pumped into the fuel-side channel via a circulating pump and mixed with air remaining in the fuel side channel to undergo a catalytic oxidation reaction. The anode exhaust gas cooler absorbs the heat released by the CPOx through the circulating gas and then enters the fuel side of the fuel stack. The anode exhaust gas is divided into two paths after releasing heat once in the anode exhaust gas cooler. One path enters the burner to undergo a chemical reaction and heating, while the other path returns to the circulating pump after releasing heat a second time in the air cooler.

[0031] This scheme utilizes the dual-mode exothermic reaction of CPOx (catalytic partial oxidation reformer) to accelerate temperature rise. In catalytic combustion mode (oxygen-rich conditions), oxygen is rapidly consumed and heat is released, increasing the fuel-side temperature. In partial oxidation reforming mode (oxygen-deficient conditions), further heat is released and hydrogen-containing reformed gas is generated, maintaining thermal equilibrium. By placing CPOx in the flue gas and using the burner exhaust gas to preheat the CPOx support (low-cost cordierite / metal support), the reaction is rapidly triggered without the need for complex heat exchange structures.

[0032] CPOx is an abbreviation for Catalytic Partial Oxidation Reformer, which converts fuel (such as methane, methanol, etc.) with limited oxygen (oxygen-deficient conditions) into hydrogen-rich reformed gas through a catalytic reaction. In this scheme, CPOx undergoes catalytic combustion under oxygen-rich conditions (excess air), rapidly consuming oxygen and releasing heat for rapid temperature rise during the start-up phase. Under oxygen-deficient conditions (excess fuel), partial oxidation reforming is performed to generate hydrogen-rich reformed gas for use in the fuel cell, while maintaining heat release.

[0033] Traditional solutions rely on the slow heat transfer from the fuel cell stack, while CPOx directly heats the circulating fuel stream through an exothermic reaction, significantly increasing the heating rate of the anode exhaust gas cooler. By arranging CPOx in the flue gas and using the burner exhaust gas to preheat the CPOx carrier (such as cordierite or a metal carrier), start-up energy consumption is reduced.

[0034] Meanwhile, this design employs a purging strategy for the gradual consumption of oxygen on the fuel side. By introducing fuel in stages, multiple fuel injections are performed within the fuel's lower explosive limit. Through the catalytic combustion of CPOx, oxygen is gradually converted into CO2 and H2O, preventing deflagration. By forming an inert mixture, the recirculation path is eventually filled with N2, CO2, and H2O. At this point, fuel is introduced without the risk of deflagration, and the replenishment of oxygen ions after stack loading prevents carbon buildup.

[0035] Optimizations were made to the co-current thermal management, with CPOx exothermic effects directly applied to the fuel side (between the circulating pump outlet and the anode exhaust gas cooler), breaking the stack temperature rise rate limitation. Furthermore, external purge gas was eliminated, relying on the CPOx reaction for self-oxygenation, thus removing the need for a steam / inert gas supply system.

[0036] CPOx directly heats the fuel-side fluid exothermically, avoiding the delay issues of traditional cross-heating and increasing the heating rate. The catalytic reaction gently consumes oxygen, preventing high-temperature deflagration; oxygen ion regulation after stack operation prevents carbon buildup, ensuring system safety and reliability. Compared to traditional solutions, it eliminates the need for expensive high-temperature heat exchangers; CPOx uses a low-cost carrier; and the purging subsystem is eliminated, simplifying the system and saving costs. It also adapts to co-current heat management system layouts, avoiding the piping design challenges caused by high-temperature cross-heating.

[0037] like Figure 1 As shown, the fuel cell stack 2 is divided into an anode side and a cathode side. It is assumed that the fuel cell stack 2 uses an oxygen ion conductor, with the anode side being the fuel side and the cathode side being the air side.

[0038] The air circuit is as follows: After being pressurized by fan 9, the air is divided into three air branches corresponding to valves A10, B11, and C12, where: The air flowing through valve A10 is heated by air preheater 3 before entering fuel cell stack 2; Air flows through valve B11 and is fed between air preheater 3 and the fuel cell stack air side inlet to regulate the fuel cell stack inlet temperature; The air flowing through valve C12 is cooled by air cooler 6 to adjust the temperature of the circulating anode tail gas, and then enters the cold side inlet of air preheater 3. It is mixed with the air from valve A10 and then sent to air preheater 3 for preheating. The preheated air is mixed with the air from valve B11 and the temperature is adjusted before entering the cathode of the fuel cell stack.

[0039] The exhaust gas generated by the cathode of the fuel cell stack enters the burner 1 to assist combustion and maintain the system's heat balance. The combustion exhaust gas returns to the air preheater 3 as a heat source to raise the temperature of the cold air. After releasing heat, the exhaust gas participates in a small amount of heat exchange through CPOx5 and provides reaction temperature for the reaction before being discharged to the designated area.

[0040] The fuel circuit is as follows: fuel flows out of fuel tank 8, mixes slightly with the circulating fluid before entering circulation pump 7 to achieve uniform mixing. The mixed fuel absorbs residual heat from the cathode exhaust gas through CPOx5 and then enters anode exhaust gas cooler 4 to continue absorbing residual heat from the anode exhaust gas, before entering the fuel side inlet of fuel cell stack 2. The high-temperature anode exhaust gas from the fuel side outlet of fuel cell stack 2 is self-cooled by anode exhaust gas cooler 4 and then split. Part of it enters burner 1 to maintain system heat balance, and the other part enters air cooler 6 to regulate temperature before participating in circulation.

[0041] Startup process: The burner can be ignited and heated via direct-flow fuel (not shown in the diagram). The heat generated sequentially heats the air preheater and CPOx, thereby increasing the stack temperature and enabling heat exchange between the air and fuel sides within the stack. The preheated anode exhaust gas exchanges heat with the anode intake gas through the anode exhaust gas cooler. During startup, the fluid circulating on the fuel side of the system is air.

[0042] Fuel purging process: At low temperatures, fuel purging the air in the fuel path poses no risk of explosion. However, during the fuel stack heating process (between 200°C and 500°C), there is a risk of fuel decomposition and carbon buildup. If fuel purging the air in the fuel path at high temperatures, there is a risk of deflagration when the fuel and air mix and come into contact with high-temperature components.

[0043] The catalysts for partial oxidation reforming of CPOx are essentially similar to those for catalytic combustion, with the air-to-fuel ratio being the determining factor for the CPOx reaction. Therefore, within the lower explosive limit of the fuel, fuel is introduced into the recirculation circuit in multiple streams. Through catalytic combustion and partial oxidation reforming reactions between the fuel and air, oxygen in the air is gradually consumed in the CPOx, resulting in fuel-side purging and simultaneously accelerating the heating of the anode exhaust gas cooler.

[0044] At this point, the fluid in the circulation path is a mixture of nitrogen, carbon dioxide, and water vapor. This fluid continues to increase the temperature on the gas combustion side, preventing carbon buildup on the fuel side of the fuel stack.

[0045] Once the fuel cell stack reaches its operating temperature, fuel is introduced, the load current is applied, and the flow rate of the circulating pump is adjusted to bring the oxygen-carbon ratio on the fuel side to the operating boundary of the battery.

[0046] If only fuel is supplied without applying current, the fuel will replace the nitrogen, carbon dioxide and water vapor in the circulation circuit and produce carbon deposits. During the application of current, oxygen ions will gradually replenish the anode side from the cathode through CPOx, thereby maintaining the oxygen-carbon ratio and preventing the generation of carbon deposits on the fuel side.

[0047] The catalyst used in CPOx enables catalytic combustion or partial reforming reactions between air and fuel in different proportions. Both reactions are exothermic, effectively addressing the slow heating rate of the anode exhaust gas cooler. During the reaction, the oxygen content on the fuel side is gradually consumed, achieving the conversion of oxygen into carbon dioxide and water. This prevents deflagration when fuel is introduced at high temperatures and maintains the oxygen-to-carbon ratio to prevent carbon buildup. It also effectively increases the heating rate of the co-current heat exchange system at a relatively low cost.

[0048] The system can purge the fuel side without water vapor or inert gas, simplifying the complexity of the fuel cell system, effectively improving system reliability and reducing cost and complexity.

[0049] In traditional methods, while co-current thermal management simplifies piping layout and avoids cross-heat exchange, fuel-side heating relies on the fuel cell stack, resulting in slow start-up speeds. This solution embeds the CPOx (Catalytic Partial Oxidation Reformer) into the fuel cycle loop, utilizing its exothermic reaction (catalytic combustion / partial oxidation) to directly heat the fuel stream, overcoming the stack's heat transfer rate limitations. Simultaneously, the CPOx is placed in the flue gas, using the combustor's flue gas as a heat source to preheat the catalyst, reducing start-up energy consumption.

[0050] Traditional fuel purging methods pose safety hazards. Low-temperature purging leads to fuel decomposition and carbon buildup, while high-temperature purging can easily cause detonation when fuel mixes with air. This solution introduces fuel in stages, gradually converting oxygen into an inert mixture of nitrogen, carbon dioxide, and water vapor under CPOx catalytic combustion mode before introducing the fuel, thus preventing detonation. During normal operation, cathode oxygen ions are replenished to the anode side via CPOx, dynamically adjusting the oxygen-carbon ratio to prevent carbon buildup.

[0051] Traditional methods require additional high-temperature heat exchangers or purge gases (such as N2 or steam), increasing costs and potential points of failure. This solution introduces CPOx to simultaneously perform reforming, exothermic, and oxygen removal functions, integrating multiple functions and eliminating the need for a separate purge system.

[0052] Example 2: A control method for a rapidly heating fuel cell system includes the following steps: Upon startup, the burner ignites and heats up, and the circulation loops of the cathode and anode begin to heat up; During fuel purging and heating to the set temperature, fuel is gradually introduced within the lower explosive limit of the fuel. The fuel reacts with air in CPOx to form a mixture of nitrogen, carbon dioxide and water vapor, which further heats the fuel cell stack. During normal operation, once the operating temperature is reached, fuel is continuously supplied, and the oxygen-to-carbon ratio is maintained within the set range by adjusting the flow rate of the circulating pump.

[0053] Startup process: The burner can be ignited and heated by direct-flow fuel (not shown in the diagram). The heat generated sequentially heats the air preheater and CPOx, thereby increasing the stack temperature and enabling heat exchange between the air and fuel sides within the stack. The anode exhaust gas generated by the stack exchanges heat with the anode intake gas through the anode exhaust gas cooler, thus providing anode intake gas for the fuel. During startup, the fluid circulating on the fuel side of the system is air.

[0054] Fuel purging process: At low temperatures, fuel purging the air in the fuel path poses no risk of explosion. However, during the fuel stack heating process (between 200°C and 500°C), there is a risk of fuel decomposition and carbon buildup. If fuel purging the air in the fuel path at high temperatures, there is a risk of deflagration when the fuel and air mix and come into contact with high-temperature components.

[0055] The catalysts for partial oxidation reforming of CPOx are essentially similar to those for catalytic combustion, with the air-to-fuel ratio being the determining factor for the CPOx reaction. Therefore, within the lower explosive limit of the fuel, fuel is introduced into the recirculation circuit in multiple streams. Through catalytic combustion and partial oxidation reforming reactions between the fuel and air, oxygen in the air is gradually consumed in the CPOx, resulting in fuel-side purging and simultaneously accelerating the heating of the anode exhaust gas cooler.

[0056] At this point, the fluid in the circulation path is a mixture of nitrogen, carbon dioxide, and water vapor. This fluid continues to increase the temperature on the gas combustion side, preventing carbon buildup on the fuel side of the fuel stack.

[0057] Once the fuel cell stack reaches its operating temperature, fuel is introduced, the load current is applied, and the flow rate of the circulating pump is adjusted to bring the oxygen-carbon ratio on the fuel side to the operating boundary of the battery.

[0058] If only fuel is supplied without applying current, the fuel will replace the nitrogen, carbon dioxide and water vapor in the circulation circuit and produce carbon deposits. During the application of current, oxygen ions will gradually replenish the anode side from the cathode through CPOx, thereby maintaining the oxygen-carbon ratio and preventing the generation of carbon deposits on the fuel side.

[0059] During fuel purging, fuel is introduced into the circulation path in multiple streams. The calculation process is as follows: Figure 2 As shown, it includes the following steps; Calculate the total fuel-side volume Q (assuming the fuel is gas combustion) based on the total volume of the fuel circulation pipeline (including the stack, CPOx, anode exhaust gas cooler, etc.) in the fuel system. Assuming the initial gas supply is air (containing 21% oxygen), calculate the required fuel amount a (in terms of methane) based on a complete combustion reaction. Calculate the minimum injection rate c and injection time t based on the minimum methane concentration b%. Specifically, since the lower explosive limit (LEL) of methane in air is 5%, the methane concentration injected each time must be ≤ b% (e.g., b = 3%, leaving a margin). Calculate the minimum cumulative injection time d based on a / (c×t).

[0060] As a further implementation, the total fuel-side volume Q is calculated as shown in the following formula: Q=V 管路 +V电堆阳极 +V CPOx +V 换热器 ; Among them, V 管路 V 电堆阳极 V CPOx V 换热器 These are the fuel-side volumes for the piping, fuel cell stack, CPOx, and heat exchanger (referring to the anode exhaust gas cooler), respectively.

[0061] As a further implementation method, complete combustion reaction (taking methane as an example): CH4+2O2→CO2+2H2OCH4+2O2→CO2+2H2O.

[0062] As a further implementation method, the total oxygen amount is calculated. n O2 As shown in the following formula: n O2 =0.21× ; in, For an ideal gas law, P For pressure, T For temperature, R is the gas constant.

[0063] As a further implementation method, the required fuel quantity 'a' is calculated as shown in the following formula: a=n O2 × ×10 6 ; in, This represents the molar mass of methane.

[0064] As a further implementation method, the minimum injection rate c = gas-side flow rate × b% × ρ CH4 ; The gas flow rate is determined by the circulating pump. ρ CH4 The density is that of methane.

[0065] As a further implementation method, the time t for each introduction should ensure that methane reacts fully in CPOx to avoid excessively high local concentrations. The time t should be selected based on empirical values ​​(e.g., t = 1~5 s).

[0066] As a further implementation method, the single injection volume = c × t.

[0067] As a further implementation method, the cumulative number of passes = a / (c×t), which is rounded up to obtain A.

[0068] As a further implementation, the total purging time is the minimum cumulative injection time, and the minimum cumulative injection time d = A × t.

[0069] In actual operation, adjustments are made at any time based on the oxygen concentration and CPOx temperature in the air. For example, the flow is stopped when the oxygen concentration is less than the set value, and the flow time is extended when the temperature is too low.

[0070] In traditional methods, while co-current thermal management simplifies piping layout and avoids cross-heat exchange, fuel-side heating relies on the fuel cell stack, resulting in slow start-up speeds. This solution embeds the CPOx (Catalytic Partial Oxidation Reformer) into the fuel cycle loop, utilizing its exothermic reaction (catalytic combustion / partial oxidation) to directly heat the fuel stream, overcoming the stack's heat transfer rate limitations. Simultaneously, the CPOx is placed in the flue gas, using the combustor's flue gas as a heat source to preheat the catalyst, reducing start-up energy consumption.

[0071] Traditional fuel purging methods pose safety hazards. Low-temperature purging leads to fuel decomposition and carbon buildup, while high-temperature purging can easily cause detonation when fuel mixes with air. This solution introduces fuel in stages, gradually converting oxygen into an inert mixture of nitrogen, carbon dioxide, and water vapor under CPOx catalytic combustion mode before introducing the fuel, thus preventing detonation. During normal operation, cathode oxygen ions are replenished to the anode side via CPOx, dynamically adjusting the oxygen-carbon ratio to prevent carbon buildup.

[0072] Traditional methods require additional high-temperature heat exchangers or purge gases (such as N2 or steam), increasing costs and potential points of failure. This solution introduces CPOx to simultaneously perform reforming, exothermic, and oxygen removal functions, integrating multiple functions and eliminating the need for a separate purge system.

[0073] CPOx exhibits high reaction flexibility, enabling catalytic combustion (rapid heating + oxygen removal) in oxygen-rich environments and partial oxidation reforming (hydrogen production + heat preservation) in oxygen-deficient environments. Furthermore, its carrier is cordierite / metal carrier + precious metal coating, resulting in low cost, high temperature resistance, and no risk of leakage.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fuel cell system with rapid heating, characterized in that, Includes a cathode and an anode, with the cathode on the air side and the anode on the fuel side: After being pressurized by a fan, the air is divided into three paths. One path absorbs heat from the burner through an air preheater before entering the cathode of the fuel cell stack. Another path enters the fuel cell stack directly to regulate the inlet temperature of the cathode. The third path absorbs secondary waste heat from the anode exhaust gas through an air cooler, is preheated a second time by the air preheater, and then enters the cathode of the fuel cell stack. The cathode exhaust gas is heated by the burner, then releases heat once through the air preheater, and then releases heat a second time through CPOx, providing the heat required for the reaction of CPOx. Fuel is pumped into the CPOx via a circulating pump and mixes with the air remaining in the fuel-side channel to undergo a catalytic oxidation reaction. The anode exhaust gas cooler absorbs the heat released by the CPOx through the circulating gas and then enters the fuel side of the fuel stack. The anode exhaust gas is divided into two paths after releasing heat once through the anode exhaust gas cooler. One path enters the burner to undergo a chemical reaction and heating, while the other path returns to the circulating pump after releasing heat a second time through the air cooler.

2. The fuel cell system with rapid heating as described in claim 1, characterized in that, After being pressurized by a fan, the air is divided into three streams, each with its own flow rate controlled by a corresponding valve: The amount of air entering the air preheater is adjusted by changing the opening degree of valve A, and the amount of air entering the fuel cell cathode is adjusted by changing the opening degree of valve B, thereby indirectly controlling the temperature at the inlet side of the fuel cell cathode. The amount of air entering the air cooler to absorb the secondary waste heat of the anode tail gas is adjusted by changing the opening degree of valve C.

3. The fuel cell system with rapid heating as described in claim 1, characterized in that, The cathode exhaust gas is heated by the burner and then passes through the air preheater and CPOx in sequence. The air preheater releases the heat of the combustion exhaust gas into the air entering the cathode of the fuel cell stack, and the CPOx further releases the heat of the combustion exhaust gas into the fuel entering the anode of the fuel cell stack. The combustion exhaust gas after secondary heat release is discharged to a designated area.

4. The rapid heating fuel cell system as described in claim 1, characterized in that, The fuel is stored in a fuel tank, and the fuel in the fuel tank is fed into the burner and the circulation pump respectively. The circulation pump generates the circulation power of the fuel, so that the fuel passes through the CPOx and the anode exhaust gas cooler in sequence before entering the anode of the fuel cell stack.

5. The fuel cell system with rapid heating as described in claim 1, characterized in that, The CPOx mixes fuel with burner exhaust gas that has been heated by an air preheater, and through a catalytic oxidation reaction, the fuel undergoes catalytic combustion under oxygen-rich conditions for rapid temperature rise during the start-up phase; under oxygen-deficient conditions, it undergoes partial oxidation reforming to generate hydrogen-rich reformed gas for use in the power stack, while maintaining heat release.

6. The fuel cell system with rapid heating as described in claim 1, characterized in that, After the anode exhaust gas releases heat through the anode exhaust gas cooler, one path leads to the burner for heating, while the other path passes through the air cooler to transfer preheated heat to the air before returning to the circulation pump.

7. A control method for a fuel cell system according to any one of claims 1-6, characterized in that, Includes the following steps: Upon startup, the burner ignites and heats up, and the circulation loops of the cathode and anode begin to heat up; During fuel purging and heating to the set temperature, fuel is gradually introduced within the lower explosive limit of the fuel. The fuel reacts with air in CPOx to form a mixture of nitrogen, carbon dioxide and water vapor, which further heats the fuel cell stack. During normal operation, once the operating temperature is reached, fuel is continuously supplied, and the oxygen-to-carbon ratio is maintained within the set range by adjusting the flow rate of the circulating pump.

8. The control method for a rapidly heating fuel cell system as described in claim 7, characterized in that, Start-up is specifically as follows: fuel is introduced into the burner for ignition and heating. The resulting high-temperature flue gas sequentially heats the air preheater and CPOx to raise the stack temperature. The fluids on the air side and fuel side of the stack exchange heat within the stack. The preheated anode exhaust gas exchanges heat with the anode intake gas through the anode exhaust gas cooler, further heating the stack.

9. The control method for a rapidly heating fuel cell system as described in claim 7, characterized in that, Fuel purging specifically involves introducing fuel in stages when the fuel stack reaches the set temperature, within the lower explosive limit of the fuel. The fuel and air undergo catalytic combustion and partial oxidation reforming reactions in CPOx, converting oxygen in the air into carbon dioxide and water vapor, thereby raising the temperature of the anode exhaust gas cooler.

10. The control method for a rapidly heating fuel cell system as described in claim 7, characterized in that, Normal operation is as follows: after the fuel cell stack reaches the operating temperature, fuel is continuously supplied, and the flow rate of the circulation pump is adjusted according to the load current to maintain the oxygen-carbon ratio on the fuel side within the set range.

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