A high-temperature methanol reforming fuel cell system and operating process for achieving carbon circulation

Abstract

The present invention belongs to the field of fuel cell technology, and particularly relates to a high-temperature methanol reforming fuel cell system and operating process that achieves carbon circulation. The system includes a fuel cell stack, a methanol steam reforming hydrogen production reactor, a carbon dioxide hydrogenation methanol production reactor, and a water electrolysis module; hydrogen produced by the methanol steam reforming hydrogen production reactor enters the anode of the fuel cell stack through a pipeline, and the cathode of the fuel cell stack is fed by an air pump. Hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack to generate external power; liquid water recovered from the fuel cell stack tail gas is passed into the water electrolysis module to electrolyze water to produce hydrogen; carbon dioxide in the fuel cell stack tail gas and hydrogen produced by the water electrolysis module enter the carbon dioxide hydrogenation methanol production reactor through an air inlet pipeline to produce methanol. The present invention not only achieves carbon circulation in the high-temperature methanol fuel cell system and reduces carbon dioxide emissions, but also achieves the circulation of hydrogen and oxygen. Through the circulation of carbon, hydrogen, and oxygen, the energy utilization efficiency of the system is jointly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a high-temperature methanol reforming fuel cell system and an operating process for realizing carbon circulation. Background Art

[0002] A fuel cell is a device that converts chemical energy stored in compound fuels directly into electrical energy through chemical reactions. It has the advantages of high efficiency, long battery life, environmental friendliness, and low noise, and has a wide range of applications.

[0003] High-temperature methanol reforming fuel cells (HTMFCs) use methanol-water solution as fuel. A reformer converts the methanol-water solution into a mixture of H2 (hydrogen) and CO2 (carbon dioxide). The mixture then reacts in a high-temperature proton exchange membrane fuel cell stack to output electrical energy. The stack membrane electrodes utilize a high-temperature, phosphoric acid-doped polymer electrolyte membrane. The HTMFCs generally operate at temperatures between 150 and 180°C and have strong resistance to CO (carbon monoxide) poisoning. They have broad application prospects in automotive power, marine power, combined heat and power, and diesel engine replacement.

[0004] However, since the fuel cell system uses a mixture of H2 (hydrogen) and CO2 (carbon dioxide) produced by methanol steam reforming as the anode fuel of the fuel cell stack, the greenhouse gas CO2 (carbon dioxide) will continue to be emitted in the exhaust gas. Although the domestic process of using CO2 and H2 to produce methanol is relatively mature, it is difficult to capture CO2 from the atmosphere and a large amount of energy is consumed in the process. At the same time, in the current methanol reforming hydrogen fuel cell system, the reformer reaction absorbs heat and generally uses a part of the hydrogen-rich reformed gas after reforming to provide heat. This part of hydrogen only provides heat and does not serve as fuel for the fuel cell stack. The energy utilization efficiency of the system is generally between 40% and 50%, and there is still much room for improvement. Summary of the Invention

[0005] In response to the above problems, the present invention aims to provide a high-temperature methanol reforming fuel cell system and operating process that realizes carbon circulation, so as to solve the problem of low energy utilization efficiency of existing fuel cell systems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] On one hand, the present invention provides a high-temperature methanol reforming fuel cell system for realizing carbon cycle, comprising a fuel cell stack, a methanol steam reforming hydrogen production reactor, a carbon dioxide hydrogenation methanol production reactor and a water electrolysis module;

[0008] The hydrogen produced by the methanol steam reforming hydrogen production reactor enters the anode of the fuel cell stack through a pipeline. The cathode of the fuel cell stack is fed by an air pump. The hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack to generate external power.

[0009] The liquid water recovered from the cathode tail gas of the fuel cell stack is passed into the water electrolysis module to electrolyze water to produce hydrogen;

[0010] The carbon dioxide in the anode tail gas of the fuel cell stack and the hydrogen produced by the water electrolysis module enter the carbon dioxide hydrogenation to methanol reactor through the air inlet pipe to produce methanol.

[0011] The methanol steam reforming hydrogen production reactor and the carbon dioxide hydrogenation methanol production reactor are coupled into an integrated structure, and a reactor bed electric heater is arranged between the methanol steam reforming hydrogen production reactor and the carbon dioxide hydrogenation methanol production reactor. During the startup phase of the system, the reactor bed electric heater provides a heat source for the methanol steam reforming hydrogen production reactor and the carbon dioxide hydrogenation methanol production reactor; during the stable operation phase of the system, the reactor bed electric heater is turned off, and the carbon dioxide hydrogenation methanol production reactor undergoes a methanol production reaction. The reaction is an exothermic reaction, which can provide a heat source for reforming hydrogen production, maintain the temperatures of the two beds, and reduce external heating power consumption.

[0012] A methanol steam reforming hydrogen production reactor inlet and a methanol steam reforming hydrogen production reactor outlet are respectively provided at both ends of the methanol steam reforming hydrogen production reactor. The methanol steam reforming hydrogen production reactor inlet is connected to a liquid pump and a methanol aqueous solution fuel tank through a pipeline, and the methanol steam reforming hydrogen production reactor outlet is connected to the anode of the fuel cell stack through a pipeline. A coupling heat exchanger is provided on the two pipelines connected to the methanol steam reforming hydrogen production reactor inlet and the methanol steam reforming hydrogen production reactor outlet.

[0013] The high-temperature methanol reforming fuel cell system that realizes carbon circulation also includes a heating circulation system; the heating circulation system includes a circulating oil pump, a circulating oil electric heater and a circulating oil radiator connected in sequence through a circulating oil pipeline, wherein the circulating oil pipeline passes through the coupling heat exchanger, and the two ends of the circulating oil pipeline are respectively connected to the two ends of the fuel cell stack.

[0014] The two ends of the carbon dioxide hydrogenation to methanol reactor are respectively provided with a carbon dioxide hydrogenation to methanol reactor inlet and a carbon dioxide hydrogenation to methanol reactor outlet, and the carbon dioxide hydrogenation to methanol reactor inlet is connected to the air inlet pipeline; the carbon dioxide hydrogenation to methanol reactor outlet is connected to the gas cooler and the methanol aqueous solution recovery tank in sequence through pipelines.

[0015] The water electrolysis module includes an electrolytic cell and a solar power generation panel connected to the electrolytic cell. The solar power generation panel converts solar energy into direct current electricity, and the generated direct current electricity is input into the electrolytic cell. The water recovered in the electrolytic cell is electrolyzed to generate an electrochemical reaction. The hydrogen generated at the cathode of the electrolytic cell is mixed with the anode tail gas of the stack and passed into a compressor for pressurization, and then passed into the carbon dioxide hydrogenation to methanol reactor.

[0016] The water electrolysis module can also be composed of an electrolytic cell and a wind turbine connected to the electrolytic cell. The wind turbine converts the wind energy of the cooling fans in the system and the external wind energy into DC electricity, and inputs the generated DC electricity into the electrolytic cell. The water recovered in the electrolytic cell is electrolyzed to produce an electrochemical reaction. The hydrogen generated by the cathode of the electrolytic cell is mixed with the anode tail gas of the stack and passed into the compressor for pressurization, and then passed into the carbon dioxide hydrogenation to methanol reactor.

[0017] The oxygen generated by the anode of the electrolytic cell is mixed with the cathode intake air of the stack and is used as the cathode oxidant of the stack again.

[0018] The cathode tail gas of the stack is connected to the stack cathode tail gas cooler, the gas-liquid separator and the water tank in sequence through a pipeline, and the water tank is connected to the water electrolysis module through a pipeline.

[0019] On the other hand, the present invention provides an operating process of the high-temperature methanol reforming fuel cell system that realizes carbon circulation as described above. By utilizing the tail gas of the system's stack to produce methanol, the methanol steam reforming hydrogen production reactor and the carbon dioxide hydrogenation methanol production reactor are thermally coupled to achieve the circulation of carbon and fuel and the efficient utilization of internal heat, thereby reducing the carbon emissions of the methanol fuel cell system; at the same time, the water electrolysis module is combined to electrolyze the water recovered from the system's stack tail gas to produce hydrogen, which is used as the raw material for carbon dioxide hydrogenation to produce methanol. The oxygen produced by water electrolysis is reused as the oxidant for the stack cathode. Through the circulation of carbon, hydrogen and oxygen, the energy utilization efficiency of the system is improved.

[0020] The advantages and beneficial effects of the present invention are as follows: the present invention provides a high-temperature methanol reforming fuel cell system and operating process for realizing carbon circulation, which recovers and reuses CO2 (carbon dioxide) and H2 (hydrogen) from the tail gas of the fuel cell stack in the system to produce methanol, combines the methanol reforming to produce hydrogen with its reverse reaction of carbon dioxide hydrogenation to produce methanol in the system, and combines the thermal coupling design within the system to realize the circulation of carbon and fuel and the efficient utilization of internal heat, thereby reducing the carbon emissions of the methanol fuel cell system; at the same time, combined with the water electrolysis function of the solar power generation module, the water recovered from the tail gas of the fuel cell stack in the system is electrolyzed to produce hydrogen, which is used as the raw material for carbon dioxide hydrogenation to produce methanol, and the oxygen produced by water electrolysis is reused as the oxidant for the cathode of the fuel cell stack. The above circulation of C (carbon dioxide), H (hydrogen), and O (oxygen) reduces the carbon emissions of the high-temperature methanol reforming fuel cell system while also improving the energy utilization efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a high-temperature methanol reforming fuel cell system for achieving carbon cycling in one embodiment of the present invention;

[0022] Figure 2 This is a schematic structural diagram of a methanol steam reforming hydrogen production reactor coupled with a carbon dioxide hydrogenation methanol production reactor according to the present invention;

[0023] Figure 3 This is a schematic structural diagram of a water electrolysis module utilizing solar power generation according to the present invention;

[0024] Figure 4 It is a structural schematic diagram of a high-temperature methanol reforming fuel cell system for realizing carbon circulation in another embodiment of the present invention.

[0025] In the figure: 1-fuel cell, 2-methanol steam reforming hydrogen production reactor, 3-carbon dioxide hydrogenation to methanol production reactor, 4-methanol aqueous solution fuel tank, 5-gas-liquid separator, 6-liquid pump, 7-gas pump, 8-circulating oil pump, 9-circulating oil electric heater, 10-coupling heat exchanger, 11-circulating oil radiator, 12-reactor bed electric heater, 13-water tank, 14-electrolyzer, 15-solar power generation panel, 16-compressor, 17-gas cooler, 18-methanol aqueous solution recovery tank, 19-fuel cell cathode tail gas cooler, 20-wind turbine, A-methanol steam reforming hydrogen production reactor inlet, B-methanol steam reforming hydrogen production reactor outlet, C-carbon dioxide hydrogenation to methanol reactor inlet, D-carbon dioxide hydrogenation to methanol reactor outlet, E-electrolyzer hydrogen side outlet, F-electrolyzer oxygen side outlet. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] See also Figures 1 to 3As shown, an embodiment of the present invention provides a high-temperature methanol reforming fuel cell system for realizing carbon cycle, comprising a fuel cell stack 1, a methanol steam reforming hydrogen production reactor 2, a carbon dioxide hydrogenation methanol production reactor 3 and a water electrolysis module; the methanol steam reforming hydrogen production reactor 2 produces hydrogen by methanol steam reforming, and the hydrogen prepared by the methanol steam reforming hydrogen production reactor 2 enters the anode of the fuel cell stack 1 through a pipeline, and the cathode of the fuel cell stack 1 is fed by an air pump 7, and hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack 1 to realize external power supply; liquid water recovered in the cathode tail gas of the fuel cell stack 1 is passed into the water electrolysis module to electrolyze water to produce hydrogen; the carbon dioxide in the anode tail gas of the fuel cell stack 1 and the hydrogen produced by the water electrolysis module enter the carbon dioxide hydrogenation methanol production reactor 3 through the air inlet pipeline, and the carbon dioxide hydrogenation methanol production reactor 3 produces methanol by carbon dioxide hydrogenation.

[0028] See also Figure 1 As shown, in the embodiment of the present invention, the cathode tail gas of the fuel cell stack 1 is connected to the fuel cell stack cathode tail gas cooler 19, the gas-liquid separator 5 and the water tank 13 in sequence through a pipeline, and the water tank 13 is connected to the water electrolysis module through a pipeline.

[0029] See also Figure 1 and Figure 2 As shown, in an embodiment of the present invention, the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3 are coupled into an integrated structure, and a reactor bed electric heater 12 is arranged between the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3. During the system startup phase, the reactor bed electric heater 12 provides a heat source for the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3. During the system stable operation phase, the reactor bed electric heater 12 is turned off, and the carbon dioxide hydrogenation methanol production reactor 3 undergoes a methanol production reaction. The reaction is an exothermic reaction, which can provide a heat source for reforming hydrogen production, maintain the temperature of the two beds, and reduce the power consumption of external heating. A methanol steam reforming hydrogen production reactor inlet A and a methanol steam reforming hydrogen production reactor outlet B are respectively provided at both ends of the methanol steam reforming hydrogen production reactor 2. The methanol steam reforming hydrogen production reactor inlet A is connected to the liquid pump 6 and the methanol aqueous solution fuel tank 4 through a pipeline; the methanol steam reforming hydrogen production reactor outlet B is connected to the anode of the fuel cell stack 1 through a pipeline, and a coupling heat exchanger 10 is provided on the two pipelines connecting the methanol steam reforming hydrogen production reactor inlet A and the methanol steam reforming hydrogen production reactor outlet B.

[0030] Furthermore, the present invention provides a high-temperature methanol reforming fuel cell system for realizing carbon circulation, which also includes a heating circulation system; the heating circulation system includes a circulating oil pump 8, a circulating oil electric heater 9 and a circulating oil radiator 11 connected in sequence through a circulating oil pipeline, wherein the circulating oil pipeline passes through a coupling heat exchanger 10, and the two ends of the circulating oil pipeline are respectively connected to the two ends of the fuel cell stack 1.

[0031] See also Figure 1 and Figure 2 As shown, in the embodiment of the present invention, a carbon dioxide hydrogenation to methanol reactor inlet C and a carbon dioxide hydrogenation to methanol reactor outlet D are respectively provided at both ends of the carbon dioxide hydrogenation to methanol reactor 3, and the carbon dioxide hydrogenation to methanol reactor inlet C is connected to the air inlet pipeline; the carbon dioxide hydrogenation to methanol reactor outlet D is connected to the gas cooler 17 and the methanol aqueous solution recovery tank 18 in sequence through pipelines.

[0032] See also Figure 3 As shown, in an embodiment of the present invention, the water electrolysis module includes an electrolytic cell 14 and a solar panel 15 connected to the electrolytic cell 14. The solar panel 15 converts solar energy into DC electricity, and the generated DC electricity is input into the electrolytic cell 14 to electrolyze the water recovered in the electrolytic cell 14 to generate an electrochemical reaction. The electrolytic cell 14 is provided with an electrolytic cell hydrogen side outlet E and an electrolytic cell oxygen side outlet F on both sides. The hydrogen generated by the cathode of the electrolytic cell 14 is discharged from the electrolytic cell hydrogen side outlet E, and is mixed with the anode tail gas of the stack 1 and passed into the compressor 16 for pressurization, and then passed into the carbon dioxide hydrogenation to methanol reactor 3. The oxygen generated by the anode of the electrolytic cell 14 is discharged through the electrolytic cell oxygen side outlet F, and is mixed with the cathode inlet gas of the stack 1 and is used as the cathode oxidant of the stack again.

[0033] See also Figure 4 As shown, in an embodiment of the present invention, the water electrolysis module may also be composed of an electrolytic cell 14 and a wind turbine 20 connected to the electrolytic cell 14. The wind turbine 20 converts the wind energy of the cooling fans in the circulating oil radiator 11, the gas cooler 17 and the stack cathode exhaust cooler in the system and the external wind energy into DC power, inputs the generated DC power into the electrolytic cell 14, and electrolyzes the recovered water in the electrolytic cell 14 to generate an electrochemical reaction.

[0034] An embodiment of the present invention provides a high-temperature methanol reforming fuel cell system for achieving carbon recycling, the operating principle of which is as follows:

[0035] During the startup phase of the fuel cell system, a lithium battery drives a heater to heat the fuel cell stack 1, the methanol steam reforming hydrogen production reactor 2, and the carbon dioxide hydrogenation methanol production reactor 3 to the operating temperature. The fuel methanol aqueous solution is then pumped into the coupled heat exchanger 10, evaporated using the heat of the circulating thermal oil, and then passed into the methanol steam reforming hydrogen production reactor 2, where a methanol reforming hydrogen production reaction occurs. The hydrogen-rich gas after the reaction is passed into the fuel cell stack anode, and the fuel cell stack cathode is fed using an air pump. Hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack to provide external power supply.

[0036] During the stable operation phase of the fuel cell system, the anode tail gas of the stack is passed into the compressor 16, pressurized to ~3 MPa, and then passed into the carbon dioxide hydrogenation to methanol reactor 3 to produce methanol. The reaction is exothermic and can provide a heat source for reforming hydrogen production, maintain the temperature of the two beds, and reduce external heating power consumption.

[0037] In the fuel cell system, the reaction gas discharged from the carbon dioxide hydrogenation to methanol reactor 3 can be cooled and subjected to vapor-liquid separation to obtain a methanol aqueous solution. After distillation, impurity removal, liquid replenishment and other treatments, the concentration of the methanol aqueous solution is adjusted to be consistent with the concentration of the imported fuel and reused as fuel, thereby realizing the carbon (carbon dioxide) cycle and reducing carbon dioxide emissions. At the same time, it realizes the hydrogen (hydrogen) cycle. Through the carbon and hydrogen cycles, the energy utilization efficiency of the system is improved.

[0038] The fuel cell system is equipped with a water electrolysis module. Liquid water recovered from the fuel cell stack cathode exhaust is passed into an electrolyzer 14. External solar power is used to electrolyze the water recovered in the electrolyzer 14. Hydrogen generated at the electrolyzer cathode mixes with the fuel cell stack anode exhaust, which is then passed through a compressor 16 into the carbon dioxide hydrogenation to methanol reactor 3 to produce methanol. This compensates for the hydrogen shortage associated with methanol production using only the fuel cell stack anode exhaust, converting the majority of the carbon dioxide back into methanol. In this fuel cell system, oxygen generated at the electrolyzer anode mixes with the fuel cell stack cathode intake air and serves as the stack cathode oxidant, enabling oxygen circulation and reducing the air pump flow rate, thereby reducing air pump power consumption.

[0039] Another embodiment of the present invention provides an operating process of a high-temperature methanol reforming fuel cell system that realizes carbon circulation as described above. By utilizing the exhaust gas of the fuel cell stack 1 in the system to produce methanol, the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3 are thermally coupled to achieve the circulation of carbon and fuel and the efficient utilization of internal heat, thereby reducing the carbon emissions of the methanol fuel cell system; at the same time, the water electrolysis module is combined to electrolyze the water recovered from the exhaust gas of the system fuel cell stack to produce hydrogen, which is used as the raw material for carbon dioxide hydrogenation to produce methanol. The oxygen produced by water electrolysis is reused as the oxidant for the cathode of the fuel cell stack 1. Through the circulation of carbon, hydrogen and oxygen, the energy utilization efficiency of the system is improved. Example

[0040] See also Figure 1 As shown, the present invention provides a high-temperature methanol reforming fuel cell system that realizes carbon circulation. During the startup phase, the lithium battery drives the circulating oil electric heater 9 to heat the circulating thermal oil of the fuel cell stack, thereby heating the fuel cell stack 1 to an operating temperature of 160°C. At the same time, the reactor bed electric heater 12 heats the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3 to their beds to 300°C. Figure 2As shown, the bed layers of the methanol steam reforming hydrogen production reactor 2 and the carbon dioxide hydrogenation methanol production reactor 3 are coupled and connected in an integrated manner, and heat can be transferred to each other. A reactor bed electric heater 12 is provided in the middle, which is mainly used for starting heating. After reaching the temperature condition, the 60vol% methanol aqueous solution in the methanol aqueous solution fuel tank 4 is pumped into the coupled heat exchanger 10 by the liquid pump 6. After being evaporated by the heat of the circulating heat transfer oil, it is passed from the methanol steam reforming hydrogen production reactor inlet A to the methanol steam reforming hydrogen production reactor 2, and a methanol reforming hydrogen production reaction occurs. As shown in formula (1), the reaction is an endothermic reaction. The hydrogen-rich gas (~65% hydrogen, ~21% carbon dioxide, ~13% water vapor, ~1% carbon monoxide, etc.) after the reaction is discharged from the methanol steam reforming hydrogen production reactor outlet B, cooled to ~160°C by the coupled heat exchanger 10, and then passed into the anode of the fuel cell stack 1. The cathode of the fuel cell stack 1 is fed by the gas pump 7. The hydrogen and oxygen undergo an electrochemical reaction (2) in the fuel cell stack 1, realizing external power supply.

[0041] The chemical reaction equation for the above methanol steam reforming hydrogen production method is as follows:

[0042] CH3OH+H2O→CO2+3H2 ∆H 298 = 49.5 kJ·mol - 1 (1)

[0043] The chemical reaction equation in the above stack is as follows:

[0044] 2H2 + O2 → 2H2O (2)

[0045] See also Figure 1 As shown, during the stable operation phase of the system, since hydrogen-rich gas instead of pure hydrogen is introduced into the anode of the stack 1, in order to ensure the power generation performance of the stack 1, hydrogen-rich gas with a stoichiometric ratio of 1.15 to 1.4 times that of hydrogen is usually used at the anode. For example, after hydrogen-rich gas with a stoichiometric ratio of 1.3 times that of hydrogen is introduced into the stack 1, the anode tail gas of the stack 1 is composed of ~30% hydrogen, ~42% carbon dioxide, ~26% water vapor, and ~2% carbon monoxide. The anode tail gas of the stack 1 is introduced into the compressor 16, pressurized to 3 MPa, and then introduced into the carbon dioxide hydrogenation to methanol reactor 3 from the inlet C of the carbon dioxide hydrogenation to methanol reactor, where a methanol production reaction occurs, as shown in formula (3). The carbon dioxide hydrogenation to methanol reaction is an exothermic reaction, which can provide a heat source for reforming hydrogen production and maintain the reaction temperature of the two beds at the same time, see Figure 2As shown. During stable operation, external bed heating can be stopped or intermittently started, significantly reducing the heating power consumption of the external reactor bed electric heater 12. The reaction gas is discharged from outlet D of the carbon dioxide hydrogenation to methanol reactor, cooled by a gas cooler 17, and separated by a gas-liquid separator before entering a methanol-water recovery tank 18 to obtain a methanol-water solution. After distillation, impurity removal, and rehydration, the concentration is adjusted to a 60% methanol-water solution, consistent with the concentration of the imported fuel, and reused as fuel. This realizes the carbon (carbon dioxide) cycle, reduces carbon dioxide emissions, and simultaneously realizes the hydrogen (hydrogen) cycle. Through the carbon and hydrogen cycles, the energy utilization efficiency of the system is improved.

[0046] CO2+3H2→CH3OH+H2O ∆H 298 = -49.5 kJ·mol - 1 (3)

[0047] See also Figure 1 As shown, since the stack 1 consumes most of the hydrogen and generates water, the hydrogen in the anode tail gas of the stack 1 used as hydrogen to produce methanol by hydrogenation of carbon dioxide is insufficient to recover most of the carbon dioxide and convert it into methanol. Therefore, the system of the present invention recovers water from the cathode tail gas of the stack 1 and is equipped with an electrolytic cell 14 for electrolyzing water to produce hydrogen. The recovered liquid water is introduced into the electrolytic cell 14. The solar energy is converted into DC power by the photovoltaic effect using a solar panel 15 externally, or the wind energy of each cooling fan in the system and the external wind energy are converted into DC power by a wind turbine 20. The generated DC power is input into the electrolytic cell 14, and the water recovered in the electrolytic cell 14 is electrolyzed to generate an electrochemical reaction. Formula (4) is used. Figure 3 and Figure 4 As shown, hydrogen generated at the cathode of electrolyzer 14 is discharged from the hydrogen outlet E of the electrolyzer, mixed with the anode tail gas of fuel cell stack 1, and passed into compressor 16. After being pressurized to ~3 MPa, it is passed into carbon dioxide hydrogenation to methanol reactor 3, where a methanol production reaction occurs. This compensates for the lack of hydrogen when using only the anode tail gas of stack 1 to produce methanol, converting most of the carbon dioxide back into methanol. If external conditions allow, the addition of a small amount of water can convert all of the carbon dioxide into methanol, achieving zero carbon dioxide emissions. Simultaneously, oxygen generated at the anode of electrolyzer 14 is discharged from the oxygen outlet F of the electrolyzer, mixed with the cathode inlet gas of fuel cell stack 1, and re-used as the cathode oxidant of stack 1, achieving oxygen circulation and reducing the cathode air supply flow rate, thereby reducing the power consumption of air pump 7. The above system and operating process not only realizes the carbon (carbon dioxide) circulation in the high-temperature methanol fuel cell system, reducing carbon dioxide emissions, but also realizes the circulation of hydrogen (hydrogen) and oxygen (oxygen). Through the circulation of carbon, hydrogen, and oxygen, the energy utilization efficiency of the system is improved.

[0048] The chemical reaction equation in the above electrolytic cell is as follows:

[0049] 2H2O→2H2+O2 (4)

[0050] The fuel cell system of the present invention carries 100L of methanol aqueous solution (60% volume concentration), maintains the bed temperature of the methanol steam reforming hydrogen production reactor at 220-300°C, the bed temperature of the carbon dioxide hydrogenation methanol production reactor at 270-350°C, the stack temperature at 160-165°C, the circulating oil temperature at 150-155°C, and the fuel flow rate of 170mL / min methanol aqueous solution and 400mA / cm 2 The rated output power at the working point is 11kW, the stable working time is ~10h, and the CO2 (carbon dioxide) emission is ~34.6m 3 , the system energy utilization efficiency can reach ~40%; when the system does not open the water recovery, electrolyzer and other modules, the CO2 recovery capacity is 5~7m 3 The CO2 recovery rate is 15~20%, and 15~20L of methanol aqueous solution (60% volume concentration) can be recycled and prepared. The stable working time is extended to 11.5~12h, and the system energy utilization efficiency can reach 47~50%; when the system starts water recovery, electrolyzer and other modules, the CO2 recovery volume is 19~30m 3 The CO2 recovery rate is 55~90%, and 55~90L of methanol aqueous solution (60% volume concentration) can be recycled and prepared. The stable working time is extended to 15.5~19h, and the system energy utilization efficiency can reach more than 90%.

[0051] The present invention provides a high-temperature methanol reforming fuel cell system and operating process for achieving carbon circulation, including a high-temperature proton exchange membrane fuel cell (HT-PEMFC) system that uses hydrogen-rich gas produced by methanol steam reforming as fuel cell stack fuel. The system recovers and reuses CO2 (carbon dioxide) and H2 (hydrogen) from the system's stack tail gas to produce methanol, combining methanol reforming to produce hydrogen and its reverse reaction, carbon dioxide hydrogenation to produce methanol, in the system. Combined with the system's internal thermal coupling design, this achieves carbon and fuel circulation and efficient utilization of internal heat, thereby reducing carbon emissions from the methanol fuel cell system. Simultaneously, combined with the water electrolysis function of a solar power generation module, water recovered from the system's stack tail gas is electrolyzed to produce hydrogen, which serves as a raw material for carbon dioxide hydrogenation to produce methanol. The oxygen produced by water electrolysis is reused as an oxidant for the stack cathode. The above C (carbon dioxide), H (hydrogen), and O (oxygen) circulation reduces carbon emissions from the high-temperature methanol reforming fuel cell system while also improving the system's energy utilization efficiency.

[0052] The above description is only an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the scope of protection of the present invention.

Claims

1. A high-temperature methanol reforming fuel cell system for achieving carbon circulation, characterized in that: It includes a fuel cell (1), a methanol steam reforming hydrogen production reactor (2), a carbon dioxide hydrogenation methanol production reactor (3) and a water electrolysis module; The hydrogen produced by the methanol steam reforming hydrogen production reactor (2) enters the anode of the fuel cell stack (1) through a pipeline, and the cathode of the fuel cell stack (1) is fed by an air pump (7). The hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack (1) to generate external power supply. The liquid water recovered from the cathode tail gas of the fuel cell (1) is passed into the water electrolysis module to electrolyze the water to produce hydrogen; The carbon dioxide in the anode tail gas of the fuel cell (1) and the hydrogen produced by the water electrolysis module enter the carbon dioxide hydrogenation to methanol reactor (3) through the air inlet pipe to produce methanol; The methanol steam reforming hydrogen production reactor (2) and the carbon dioxide hydrogenation methanol production reactor (3) are coupled into an integrated structure, and a reactor bed electric heater (12) is provided between the methanol steam reforming hydrogen production reactor (2) and the carbon dioxide hydrogenation methanol production reactor (3); the carbon dioxide hydrogenation methanol production reactor (3) produces a methanol production reaction, which is an exothermic reaction and provides a heat source for reforming hydrogen production, thereby maintaining the temperature of the two beds and reducing external heating power consumption.

2. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: During the system startup phase, the reactor bed electric heater (12) provides a heat source for the methanol steam reforming hydrogen production reactor (2) and the carbon dioxide hydrogenation methanol production reactor (3); during the system stable operation phase, the reactor bed electric heater (12) is turned off.

3. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: A methanol steam reforming hydrogen production reactor inlet (A) and a methanol steam reforming hydrogen production reactor outlet (B) are respectively provided at both ends of the methanol steam reforming hydrogen production reactor (2); the methanol steam reforming hydrogen production reactor inlet (A) is connected to a liquid pump (6) and a methanol aqueous solution fuel tank (4) through a pipeline; the methanol steam reforming hydrogen production reactor outlet (B) is connected to the anode of the fuel cell stack (1) through a pipeline; and a coupling heat exchanger (10) is provided on the two pipelines connected to the methanol steam reforming hydrogen production reactor inlet (A) and the methanol steam reforming hydrogen production reactor outlet (B).

4. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 3, characterized in that: It also includes a heating circulation system; the heating circulation system includes a circulating oil pump (8), a circulating oil electric heater (9), and a circulating oil radiator (11) connected in sequence through a circulating oil pipeline, wherein the circulating oil pipeline passes through the coupling heat exchanger (10), and the two ends of the circulating oil pipeline are respectively connected to the two ends of the fuel cell stack (1).

5. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: The two ends of the carbon dioxide hydrogenation to methanol reactor (3) are respectively provided with a carbon dioxide hydrogenation to methanol reactor inlet (C) and a carbon dioxide hydrogenation to methanol reactor outlet (D), and the carbon dioxide hydrogenation to methanol reactor inlet (C) is connected to the air inlet pipeline; the carbon dioxide hydrogenation to methanol reactor outlet (D) is connected to the gas cooler (17) and the methanol aqueous solution recovery tank (18) in sequence through pipelines.

6. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: The water electrolysis module comprises an electrolytic cell (14) and a solar panel (15) connected to the electrolytic cell (14). The solar panel (15) converts solar energy into direct current electricity, and the generated direct current electricity is input into the electrolytic cell (14). The water recovered in the electrolytic cell (14) is electrolyzed to generate an electrochemical reaction. The hydrogen generated at the cathode of the electrolytic cell (14) is mixed with the anode tail gas of the stack (1) and passed into the compressor (16) for pressurization, and then passed into the carbon dioxide hydrogenation to methanol reactor (3).

7. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: The water electrolysis module includes an electrolytic cell (14) and a wind turbine (20) connected to the electrolytic cell (14). The wind turbine (20) converts wind energy from the cooling fans in the system and external wind energy into direct current electricity, inputs the generated direct current electricity into the electrolytic cell (14), electrolyzes the water recovered in the electrolytic cell (14), and generates an electrochemical reaction. The hydrogen generated at the cathode of the electrolytic cell (14) is mixed with the anode tail gas of the stack (1) and passed into the compressor (16) for pressurization, and then passed into the carbon dioxide hydrogenation to methanol reactor (3).

8. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 6 or 7, characterized in that: The oxygen generated at the anode of the electrolytic cell (14) is mixed with the cathode air intake of the stack (1) and is used as the cathode oxidant of the stack again.

9. The high-temperature methanol reforming fuel cell system for realizing carbon cycle according to claim 1, characterized in that: The cathode tail gas of the stack (1) is connected to the stack cathode tail gas cooler (19), the gas-liquid separator (5) and the water tank (13) in sequence through pipelines, and the water tank (13) is connected to the water electrolysis module through pipelines.

10. An operating process of a high-temperature methanol reforming fuel cell system for realizing carbon cycle according to any one of claims 1 to 9, characterized in that: By utilizing the tail gas of the fuel cell stack (1) in the system to produce methanol, the methanol steam reforming hydrogen production reactor (2) and the carbon dioxide hydrogenation methanol production reactor (3) are thermally coupled to achieve the circulation of carbon and fuel and the efficient utilization of internal heat, thereby reducing the carbon emissions of the methanol fuel cell system; at the same time, the water recovered from the tail gas of the fuel cell stack in the system is electrolyzed to produce hydrogen, which is used as the raw material for carbon dioxide hydrogenation to produce methanol. The oxygen produced by water electrolysis is reused as the oxidant for the cathode of the fuel cell stack (1). Through the circulation of carbon, hydrogen and oxygen, the energy utilization efficiency of the system is improved.

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