Methanol reforming fuel cell rapid cold start system and control method

Abstract

The invention is suitable for the technical field of fuel cells, and provides a methanol reforming fuel cell rapid cold start system and a control method, the system comprises: a methanol reforming hydrogen production reactor, the methanol reforming hydrogen production reactor comprises a combustion chamber, a reforming chamber and a heat exchanger, and the combustion chamber is provided with an electrical bar; the high-temperature proton exchange membrane fuel cell is connected with the methanol reforming hydrogen production reactor, and an electric heating sheet is arranged on the high-temperature proton exchange membrane fuel cell; the air pump is connected with the reforming chamber and is used for introducing air to promote the reduction-state catalyst in the reforming chamber to perform oxidation exothermic reaction; a methanol water storage tank; and the control module is used for regulating and controlling the quantity of fuel entering the methanol reforming hydrogen production reactor module, air entering the methanol reforming hydrogen production reactor module and the high-temperature proton exchange membrane fuel cell module and controlling the starting of the electric heating bar and the electric heating sheet. According to the invention, the starting time of the methanol reforming fuel cell system within hectowatt level can be shortened to be within 10min, so that the system can quickly enter a power generation state.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a fast cold start system and a control method for a methanol reforming fuel cell. Background Art

[0002] Carbon emissions from the widespread use of fossil fuels will lead to a series of environmental problems such as climate warming. Reducing anthropogenic carbon dioxide emissions has become an important environmental issue and a severe challenge in addressing climate warming. Hydrogen has gained increasing recognition as a potential solution to carbon emissions, and hydrogen fuel cell technology is also considered a promising clean and efficient energy technology. Methanol has great potential as a hydrogen carrier, and the combination of fuel cells and methanol reformers is increasingly favored by portable applications and new energy vehicles, because methanol can be easily converted into hydrogen at lower temperatures than many other hydrocarbon fuels. Methanol steam reforming (MSR) is the most mature and efficient method for producing hydrogen from methanol.

[0003] However, compared with pure hydrogen fuel cells, the longer cold start time of methanol reforming fuel cell systems is an urgent problem to be solved. The cold start time is the time it takes for the methanol reformer to heat up from ambient temperature to operating temperature. In general, low-temperature start methods usually include electric heating and indirect heating based on fuel catalytic combustion, but these methods have obvious defects in the compactness of the reactor and the increase in the capacity of the start-up battery. At present, the slow heating rate of the reforming reactor limits the start-up time of the 100-watt methanol reforming fuel cell system. According to the product parameters of methanol reforming fuel cells of different powers at home and abroad, the cold start time of the system is generally more than 15 minutes (advent CellPack StGen 5 start-up time 15~20 minutes; nanohydrogen 200W start-up time 15~18 minutes). Even through optimization measures such as adding electric heating and improving the reactor structure, the system start-up time still exceeds 10 minutes. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a methanol reforming fuel cell rapid cold start system, aiming to solve the problems raised in the above-mentioned background technology.

[0005] The embodiment of the present invention is implemented as follows: a methanol reforming fuel cell rapid cold start system, comprising:

[0006] A methanol reforming hydrogen production reactor, comprising a combustion chamber, a reforming chamber and a heat exchanger, for catalytic combustion, maintaining reaction temperature and reforming hydrogen production, wherein an electric heating rod is arranged on the combustion chamber;

[0007] A high-temperature proton exchange membrane fuel cell is connected to the methanol reforming hydrogen production reactor, the reformed gas is supplied to the high-temperature proton exchange membrane fuel cell to generate electricity, and the remaining reformed gas is supplied to the combustion chamber for combustion to maintain the reaction temperature. The high-temperature proton exchange membrane fuel cell is provided with an electric heater;

[0008] An air pump is connected to the reforming chamber and is used to introduce air to promote the oxidation exothermic reaction of the reduced catalyst in the reforming chamber;

[0009] Methanol water storage tanks for providing fuel;

[0010] The control module is used to regulate the amount of fuel entering the methanol reforming hydrogen production reactor module and the air entering the methanol reforming hydrogen production reactor module and the high-temperature proton exchange membrane fuel cell module, as well as to control the opening of the electric heating rod and the electric heating plate.

[0011] Preferably, the system further comprises:

[0012] Pump 1, connected between the methanol water storage tank and the combustion chamber, for delivering fuel to the combustion chamber;

[0013] Pump 2, connected between the methanol water storage tank and the reforming chamber, for delivering fuel to the reforming chamber;

[0014] Fan 1, connected to the combustion chamber;

[0015] The second fan is connected to the high temperature proton exchange membrane fuel cell.

[0016] Preferably, the system further comprises a monitoring module connected to the control module, wherein the monitoring module is used to monitor the temperatures of the combustion chamber, the reforming chamber and the high-temperature proton exchange membrane fuel cell and transmit the information to the control module.

[0017] Another object of the embodiment of the present invention is to provide a control method for a methanol reforming fuel cell rapid cold start system, comprising the following steps:

[0018] Acquire the reforming chamber temperature T2 and the high-temperature proton exchange membrane fuel cell temperature T3, and enter the fast start mode;

[0019] Air is introduced into the reforming chamber, and the reduced catalyst undergoes an exothermic oxidation reaction, which promotes T2 to rise to ≥Tset1. The high-temperature proton exchange membrane fuel cell starts electric heating, and T3 rises to ≥Tset2.

[0020] Air and methanol water are introduced into the reforming chamber, and an exothermic reaction of methanol catalytic reduction occurs, and the temperature T2 is raised to a temperature ≥ the target reaction temperature Tset3 for methanol reforming hydrogen production;

[0021] The reformed gas is purged, T2 is heated to ≥Tset4, T3 is heated to ≥Tset5, the power generation stage is carried out, and the startup process is completed.

[0022] Preferably, the Tset2 is 120°C and the Tset5 is 150°C.

[0023] A methanol reforming fuel cell rapid cold start system provided in an embodiment of the present invention optimizes the methanol reforming fuel cell system in the prior art, and realizes the heating of the reactor and the fuel cell stack by setting an electric heating structure. The rapid cold start of the system is realized by combining the characteristics of the methanol reforming hydrogen production reduction catalyst with the chemical chain combustion reaction (Cu+0.5O2→CuO and CH3OH+CuO→3Cu+H2O+CO), and the start-up time of a methanol reforming fuel cell system within a hundred watts can be shortened to within 10 minutes, so that the system can quickly enter the power generation state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A block diagram of a methanol reforming fuel cell rapid cold start system provided by an embodiment of the present invention;

[0025] Figure 2 A flow chart of a control method for a methanol reforming fuel cell rapid cold start system provided by an embodiment of the present invention;

[0026] Figure 3 A specific flow chart of a control method for a methanol reforming fuel cell rapid cold start system provided by an embodiment of the present invention;

[0027] Figure 4 A graph showing the temperature rise curve of the electric heating of the fuel cell stack of a 125W methanol reforming fuel cell system provided in an embodiment of the present invention;

[0028] Figure 5 A rapid temperature rise curve diagram of the reforming chamber of a 125W methanol reforming fuel cell system provided in an embodiment of the present invention;

[0029] Figure 6 This is a temperature rise curve diagram of a 125W methanol reforming fuel cell system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0032] like Figure 1 As shown, a block diagram of a methanol reforming fuel cell rapid cold start system provided by an embodiment of the present invention includes:

[0033] A methanol reforming hydrogen production reactor, comprising a combustion chamber, a reforming chamber and a heat exchanger, for catalytic combustion, maintaining reaction temperature and reforming hydrogen production, wherein an electric heating rod is arranged on the combustion chamber;

[0034] A high-temperature proton exchange membrane fuel cell is connected to the methanol reforming hydrogen production reactor, the reformed gas is supplied to the high-temperature proton exchange membrane fuel cell to generate electricity, and the remaining reformed gas is supplied to the combustion chamber for combustion to maintain the reaction temperature. The high-temperature proton exchange membrane fuel cell is provided with an electric heater;

[0035] An air pump is connected to the reforming chamber and is used to introduce air to promote the oxidation exothermic reaction of the reduced catalyst in the reforming chamber;

[0036] Methanol water storage tanks for providing fuel;

[0037] A control module, used to regulate the amount of fuel entering the methanol reforming hydrogen production reactor module and the air entering the methanol reforming hydrogen production reactor module and the high-temperature proton exchange membrane fuel cell module, and to control the opening of the electric heating rod and the electric heating plate;

[0038] Specifically, the system further includes:

[0039] Pump 1, connected between the methanol water storage tank and the combustion chamber, for delivering fuel to the combustion chamber;

[0040] Pump 2, connected between the methanol water storage tank and the reforming chamber, for delivering fuel to the reforming chamber;

[0041] Fan 1, connected to the combustion chamber;

[0042] Fan 2, connected to the high temperature proton exchange membrane fuel cell;

[0043] The monitoring module is connected to the control module and is used to monitor the temperatures of the combustion chamber, the reforming chamber and the high-temperature proton exchange membrane fuel cell and transmit the information to the control module.

[0044] In one embodiment of the present invention, the methanol reforming fuel cell rapid cold start system is mainly composed of main modules such as a methanol reforming hydrogen production reactor, a high-temperature proton exchange membrane fuel cell (i.e., a fuel cell stack), and a control module, wherein the methanol reforming hydrogen production reactor is an integral reactor composed of a combustion chamber, a reforming chamber, a heat exchanger, etc. The methanol reforming hydrogen production reactor and the fuel cell stack are connected to form a whole through a heat exchanger. The reformed gas generated by fuel reforming is directly supplied to the fuel cell stack for power generation, and the remaining reformed gas is circulated to the combustion chamber, and combustion releases heat (2H2+O2→2H2O ΔH= -485.5kJ / mol (393K)) to maintain the temperature of the methanol reforming hydrogen production reaction. The control module realizes the coupling of the methanol reforming hydrogen production reaction and the fuel cell power generation;

[0045] When the system starts at normal speed, pump 1 is started to transport fuel methanol water to the combustion chamber, causing a catalytic combustion reaction (CH3OH+1.5O2→CO2+H2O ΔH= -674.7kJ / mol (393K)), raising the temperature of the reforming chamber to meet the reforming reaction conditions. After the stack generates electricity, pump 1 stops working; fan 1 provides the air required for the catalytic combustion reaction; pump 2 transports fuel to the reforming chamber to produce hydrogen, and the generated hydrogen is supplied to the stack for power generation. The excess coefficient of hydrogen is generally 1.15~1.8, and the remaining hydrogen is circulated to the combustion chamber for combustion to maintain the temperature of the reforming hydrogen production reaction. Fan 2 provides the air required for the stack to generate electricity and dissipate heat;

[0046] In addition, the system arranges electric heating rods and electric heating sheets on the combustion chamber and the stack, respectively, which can achieve the temperature increase of the reactor and the stack;

[0047] The reforming chamber uses a reduced catalyst, specifically a copper-based methanol reforming catalyst, which needs to be activated before use. Generally, a 5% H2 / N2 mixed gas is used at 250°C, GHSV=300~500h -1 The copper-based catalyst is activated for 12 to 20 hours under the conditions. After activation, the copper-based catalyst exists in the state of single copper Cu (reduced copper Cu). The system is equipped with an air pump to pass air into the reforming chamber. The reforming chamber is heated from the ambient temperature to the ignition temperature of methanol catalytic combustion by utilizing the exothermic oxidation reaction of reduced copper Cu (Cu+0.5O2→CuO ΔH= -155.8kJ / mol (298K)).

[0048] Rapid cold start can be achieved by using electric heating structure and air pump.

[0049] like Figure 2 FIG. 1 is a flow chart of a control method for a methanol reforming fuel cell rapid cold start system provided by an embodiment of the present invention, comprising the following steps:

[0050] Acquire the reforming chamber temperature T2 and the high-temperature proton exchange membrane fuel cell temperature T3, and enter the fast start mode;

[0051] Air is introduced into the reforming chamber, and the reduced catalyst undergoes an exothermic oxidation reaction, which promotes T2 to rise to ≥Tset1. The high-temperature proton exchange membrane fuel cell starts electric heating, and T3 rises to ≥Tset2.

[0052] Air and methanol water are introduced into the reforming chamber, and an exothermic reaction of methanol catalytic reduction occurs, and the temperature T2 is raised to a temperature ≥ the target reaction temperature Tset3 for methanol reforming hydrogen production;

[0053] Reforming gas purge, T2 temperature rises to ≥Tset4, T3 temperature rises to ≥Tset5, power generation phase begins, and the startup process ends;

[0054] The specific control flow chart is as follows Figure 3 As shown, the quick start mode starts, the electric heating of the battery stack is turned on (the electric heater is started), and the temperature of the battery stack is raised to T3 (the battery stack generates electricity, and after reaching the target temperature, the electric heating is stopped, and the temperature of the battery stack is controlled by adjusting the PID of the second fan);

[0055] Start the air pump to pass air into the reforming chamber. Use the exothermic oxidation reaction of reduced copper Cu (Cu+0.5O2→CuO ΔH= -155.8kJ / mol (298K)) to heat the reforming chamber from ambient temperature to the ignition temperature Tset1 of methanol catalytic combustion, referring to the reformer temperature T2. In this process, the reduced catalyst is converted into a partially oxidized catalyst. In particular, adjust the air pump to control the air velocity to 4000~4500h -1 (Space velocity = air intake volume (mL / h) / reforming catalyst volume (mL));

[0056] When the reforming chamber temperature T2 reaches the methanol catalytic combustion ignition temperature Tset1, and the stack temperature T3 reaches the set value Tset2, the air pump and pump 2 are turned on to introduce air and methanol water fuel into the reforming chamber, and further methanol and the oxidized catalyst undergo methanol catalytic reduction exothermic reaction (CH3OH+CuO→3Cu+H2O+CO2 ΔH= -208.8kJ / mol (393K)), and the reforming chamber temperature T2 is heated to the target reaction temperature Tset3 for methanol reforming hydrogen production; in this process, methanol water undergoes methanol steam reforming hydrogen production reaction (CH3OH+H2O→CO2+3H2) under the action of the catalyst, and the methanol conversion rate is about 10%~20%; in particular, CH3OH:air=0.5~0.6, and the CH3OH gas space velocity (GHSV) is 2000~2700h -1 ;

[0057] Specifically, the second pump can be turned on only when the stack temperature T3 ≥ Tset2. Tset2 is 120°C. The purpose is to ensure that the stack is in a high temperature state to prevent "flooding" and cause the stack performance to decay.

[0058] Specifically, the reformer temperature T2 is increased faster by utilizing the exothermic oxidation reaction of the reducing copper Cu, so the interval between step 1 and step 2 is determined according to the temperature rise of the fuel cell stack, and the time when T2 reaches Tset1 and T3 reaches Tset2 is ensured to be close to each other, thereby shortening the startup time of the system;

[0059] Specifically, step 3 also turns on fan 1, which, on the one hand, realizes the exhaust gas purge (gaseous water, CO2, etc.) during the startup process, and on the other hand, the H2 in the exhaust gas undergoes a catalytic combustion reaction (2H2+O2→2H2O ΔH= -485.5kJ / mol (393K)), which promotes the temperature rise rate of the reforming chamber;

[0060] When the reforming chamber temperature T2 reaches the target reaction temperature Tset3 for hydrogen production from methanol reforming, the air pump is turned off and the system enters the reforming gas purge stack state. At this time, according to the size and change of the combustion chamber temperature T1 and the reforming chamber T2, the pump 2 automatically adjusts the liquid inlet volume to achieve the purpose of purging the stack with hydrogen-rich reforming gas. The purge time is set to ≥1min. T2 is heated to Tset4 (Tset4>Tset3), and T3 is heated to Tset5, and the power generation stage is entered;

[0061] Specifically, Tset5 is generally 150°C, which can reduce the damage of impurity atmosphere to the performance of the battery stack;

[0062] Specifically, the specific method for temperature control of the power generation process in step 5 can refer to a methanol reforming fuel cell system and a reactor temperature control method in the prior art, and the specific content will not be repeated here.

[0063] Taking a methanol reforming fuel cell system with a rated power of 125W as an example, the rapid cold start process of the system is described:

[0064] The reforming chamber is filled with about 162g of copper-based methanol reforming catalyst (volume about 120mL), and after activation at 250°C using a 5% H2 / N2 mixed gas, a methanol reforming fuel cell system is formed;

[0065] Two 85W heating plates are installed on the upper and lower sides of the high-temperature proton exchange membrane fuel cell stack;

[0066] By testing the heating effect of the stack and the reforming chamber respectively, the results are as follows Figure 4 As shown, the stack T3 can be raised from room temperature to Tset5 above 150℃ in 10min; using the fast start mode, such as Figure 5 As shown, the reforming chamber temperature T2 can be raised from room temperature to Tset3 250°C in 4min;

[0067] The air pump used in the system requires an air supply pressure greater than 1 bar and a rated air volume of no less than 20L / min; the accuracy of the first and second liquid inlet pumps is no more than ±3%;

[0068] First, turn on the electric heating of the fuel cell stack. When the fuel cell stack temperature T3 is ≥90°C (about 4.5 minutes), turn on the air pump and adjust the air intake volume to 8L / min. The reforming chamber temperature T2 rises from room temperature to 120°C (Tset1) in about 2 minutes.

[0069] When the stack temperature T3 reaches 120℃ (Tset2), pump 2 starts to feed methanol water at a rate of about 6.95mL / min. The reforming chamber temperature T2 rises to 250℃ (Tset3) in about 2min. At this time, the stack temperature T3 has not yet reached the power generation condition. During this process, the fan is turned on to blow the exhaust gas out of the system.

[0070] Next, the air pump stops, and the second pump uses PID to adjust the liquid inlet according to the size and change of the combustion chamber temperature T1 and the reforming chamber T2. The control range is (0~2.5mL / min). After about 2 minutes of adjustment, the stack temperature T3 reaches 150℃ (Tset5), and the system enters the power generation process. The temperature rise curve of the whole process is shown in the figure. Figure 6 As shown, it can be seen that the 125W methanol reforming fuel cell system can be started in 10 minutes.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A methanol reforming fuel cell rapid cold start system, characterized in that: include: A methanol reforming hydrogen production reactor, comprising a combustion chamber, a reforming chamber and a heat exchanger, for catalytic combustion, maintaining reaction temperature and reforming hydrogen production, wherein an electric heating rod is arranged on the combustion chamber; A high-temperature proton exchange membrane fuel cell is connected to the methanol reforming hydrogen production reactor, the reformed gas is supplied to the high-temperature proton exchange membrane fuel cell to generate electricity, and the remaining reformed gas is supplied to the combustion chamber for combustion to maintain the reaction temperature. The high-temperature proton exchange membrane fuel cell is provided with an electric heater; An air pump is connected to the reforming chamber and is used to introduce air to promote the oxidation exothermic reaction of the reduced catalyst in the reforming chamber; Methanol water storage tanks for providing fuel; The control module is used to regulate the amount of fuel entering the methanol reforming hydrogen production reactor module and the air entering the methanol reforming hydrogen production reactor module and the high-temperature proton exchange membrane fuel cell module, as well as to control the opening of the electric heating rod and the electric heating plate.

2. The methanol reforming fuel cell rapid cold start system according to claim 1, characterized in that: The system further comprises: Pump 1, connected between the methanol water storage tank and the combustion chamber, for delivering fuel to the combustion chamber; Pump 2, connected between the methanol water storage tank and the reforming chamber, for delivering fuel to the reforming chamber; Fan 1, connected to the combustion chamber; The second fan is connected to the high temperature proton exchange membrane fuel cell.

3. The methanol reforming fuel cell rapid cold start system according to claim 1, characterized in that: The system also includes a monitoring module connected to the control module, and the monitoring module is used to monitor the temperature of the combustion chamber, the reforming chamber and the high-temperature proton exchange membrane fuel cell, and transmit the information to the control module.

4. A control method for a methanol reforming fuel cell rapid cold start system as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: Acquire the reforming chamber temperature T2 and the high-temperature proton exchange membrane fuel cell temperature T3, and enter the fast start mode; Air is introduced into the reforming chamber, and the reduced catalyst undergoes an exothermic oxidation reaction, which promotes T2 to rise to ≥Tset1. The high-temperature proton exchange membrane fuel cell starts electric heating, and T3 rises to ≥Tset2. Air and methanol water are introduced into the reforming chamber, and an exothermic reaction of methanol catalytic reduction occurs, and the temperature T2 is raised to a temperature ≥ the target reaction temperature Tset3 for methanol reforming hydrogen production; The reformed gas is purged, T2 is heated to ≥Tset4, T3 is heated to ≥Tset5, the power generation stage is carried out, and the startup process is completed.

5. The control method according to claim 4, characterized in that: The Tset2 is 120°C, and the Tset5 is 150°C.

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