Fuel cell hydrogen production system and working method

Abstract

The invention discloses a fuel cell hydrogen production system and a working method, solves the problem of long system starting time caused by the fact that purging gas is independently arranged in a hydrogen production system and then water vapor is used for direct preheating in the prior art, and has the beneficial effects of shortening the starting time and improving the starting safety. According to the specific scheme, the fuel cell hydrogen production system comprises an electrolytic cell, an air side inlet of the electrolytic cell is communicated with an air pipeline, an air side heater is arranged in the air pipeline, a water side inlet of the electrolytic cell is communicated with a water vapor pipeline, and a water side heat exchanger and a water side heater are arranged in the water vapor pipeline; a hydrogen outlet of the electrolytic cell is connected with a water side heat exchanger to exchange heat of generated hydrogen, the water vapor pipeline is provided with a first mixer, and the purging pipeline and the hydrogen pipeline communicate with the first mixer so that purging gas and hydrogen can be fed into a water side inlet of the electrolytic cell; and purging gas in the purging pipeline enters the water side inlet of the electrolytic cell through the water side heater for preheating.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell hydrogen production system and a working method. Background Art

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

[0003] A fuel cell is a device that converts the chemical energy in a fuel directly into electrical energy. It produces electricity and water as byproducts through an electrochemical reaction between a fuel (such as natural gas) and an oxidant (such as oxygen). Unlike traditional batteries, fuel cells continuously supply fuel and oxidant, thus generating electricity. They are highly efficient, clean, and widely applicable.

[0004] Hydrogen production in fuel cells is an endothermic reaction, requiring an internal heat supply to maintain high temperatures. Currently, electric heaters are commonly used. To improve the system's electrolysis efficiency, high-temperature water vapor can be directly introduced for hydrogen electrolysis. Limited by the characteristics of the fuel cell stack, a reducing atmosphere must be maintained on the cathode side of the electrolyzer to prevent oxidation during long-term operation. This requires mixing water vapor and hydrogen before the stack is introduced. During a cold start, air is present in the electrolyzer piping. To ensure system safety, the air in the system piping associated with the cathode electrolysis side must be blown away and replaced. This also prevents oxidation of the electrolysis-side electrodes at high temperatures.

[0005] The existing technology uses a single-chamber SOEC electrolytic stack, which only introduces water vapor into the electrolytic stack, completely eliminating the air supply system. During the startup process, deionized water is introduced to heat the electrolytic cell. When the set temperature is reached, the electrolytic cell draws current to start electrolysis. This has the following problems:

[0006] No purge pipeline is set up. No purge process is carried out before water vapor is introduced. Water vapor is directly introduced to heat up the electrolysis. The hydrogen generated by electrolysis may explode with the air retained in the pipeline. Some systems have purge gas introduced. The purge gas is set up in a separate pipeline, which makes the entire system setup complicated. In addition, the purge gas only plays the role of purging oxygen. After the purge gas is purged, the water side inlet of the electrolyzer is preheated, which results in a long preheating time and a long system startup time.

[0007] Directly using water vapor for preheating can easily produce liquid water, causing electrolytic cell degradation;

[0008] When the cathode side of the electrolytic cell is heated to a high temperature, only introducing water vapor to heat the system cannot maintain the reducing atmosphere inside the cathode, causing oxidation of the cathode material and resulting in degradation of the stack.

[0009] In some systems, air supply lines are installed, but the heat at the air-side outlet of the electrolyzer is not utilized;

[0010] Some systems cannot maintain a reducing atmosphere inside the cathode because the air is not purged, making it impossible to start the system safely and smoothly. Summary of the Invention

[0011] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a fuel cell hydrogen production system that can achieve safe and smooth system startup and ensure the safety of the system.

[0012] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0013] A fuel cell hydrogen production system includes an electrolyzer, wherein the air side inlet of the electrolyzer is connected to an air pipeline, an air side heater is provided in the air pipeline, the water side inlet of the electrolyzer is connected to a water vapor pipeline, a water side heat exchanger and a water side heater are provided in the water vapor pipeline, the hydrogen outlet of the electrolyzer is connected to the water side heat exchanger to exchange heat with the generated hydrogen, a first mixer is provided in the water vapor pipeline, a purge pipeline and a hydrogen pipeline are respectively connected to the first mixer so that the purge gas and hydrogen can be respectively fed into the water side inlet of the electrolyzer, and the purge gas in the purge pipeline passes through the water side heater and enters the water side inlet of the electrolyzer for preheating.

[0014] As described above, in a fuel cell hydrogen production system, the air pipeline includes an air supply mechanism, an air side heat exchanger and the air side heater connected in sequence, the air side heater is connected to the air side inlet of the electrolyzer, and the air side outlet of the electrolyzer is connected to the air side heat exchanger to preheat the cold air.

[0015] In the fuel cell hydrogen production system as described above, temperature sensors are respectively provided at each inlet and each outlet of the electrolyzer, and the temperature sensors are connected to the control center. The controller adjusts the power of the air side heater and the water side heater according to the temperature information fed back by each temperature sensor.

[0016] A fuel cell hydrogen production system as described above, wherein the air pipeline is provided with a first valve and a first flowmeter, the steam pipeline is provided with a second valve and a second flowmeter, the purge pipeline is provided with a third valve and a third flowmeter, and the hydrogen pipeline is provided with a fourth valve and a fourth flowmeter;

[0017] The first flow meter, the first valve, the second valve, the second flow meter, the third valve, the third flow meter, the fourth valve and the fourth flow meter are respectively connected to the control center.

[0018] In the fuel cell hydrogen production system as described above, the air pipeline also includes a second mixer, which is arranged between the water side heater and the electrolyzer. The hydrogen outlet of the electrolyzer is connected to the condenser after passing through the water side heat exchanger, and the condenser is connected to the gas-liquid separator.

[0019] In the fuel cell hydrogen production system as described above, the gas-liquid separator is connected to the hydrogen storage tank, the hydrogen storage tank is connected to the hydrogen pipeline, and the hydrogen storage tank is connected to the second mixer via a circulation pump.

[0020] In a second aspect, the present invention further provides a method for operating a fuel cell hydrogen production system, comprising the following contents:

[0021] The control center opens the air pipeline, and the cold air enters the air side heater to heat the cold air. The heated air enters the air side inlet of the electrolytic cell until the actual temperature of the air side inlet of the electrolytic cell reaches the required value of the air side inlet temperature of the electrolytic cell;

[0022] When the actual temperature of the air side outlet of the electrolytic cell reaches the actual temperature of the air side inlet of the electrolytic cell, the control center opens the purge pipeline, and the purge gas enters the water side heater for heating and then enters the water side inlet of the electrolytic cell to preheat the water side inlet of the electrolytic cell;

[0023] The control center opens the steam pipeline, and steam enters the water side inlet of the electrolyzer. The nitrogen flow rate is gradually reduced until it reaches 0, and the steam purge process is started;

[0024] When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the set value, the control center opens the hydrogen pipeline and introduces hydrogen to the water side inlet of the electrolyzer through the hydrogen pipeline to maintain a reducing atmosphere at the water side inlet of the electrolyzer;

[0025] When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the electrolysis temperature, the control center controls the electrolyzer to start working and continues to introduce hydrogen into the water side inlet of the electrolyzer.

[0026] According to the working method of a fuel cell hydrogen production system as described above, the control center sets the required value of the air side inlet temperature of the electrolyzer, the temperature sensor at the air side inlet of the electrolyzer obtains the actual temperature of the air side inlet of the electrolyzer and sends it to the controller, and the controller adjusts the power of the air side heater until the actual temperature of the air side inlet of the electrolyzer reaches the required value of the air side inlet temperature of the electrolyzer.

[0027] In the working method of the fuel cell hydrogen production system as described above, the purge pipeline is opened before the air pipeline is opened, so that the purge gas enters the water side inlet of the electrolyzer through the first mixer to ensure safety during startup.

[0028] In a third aspect, the present invention further provides a method for operating a fuel cell hydrogen production system, comprising the following contents:

[0029] The control center opens the air pipeline, and the cold air enters the air side heater to heat the cold air. The heated air enters the air side inlet of the electrolytic cell until the actual temperature of the air side inlet of the electrolytic cell reaches the required value of the air side inlet temperature of the electrolytic cell;

[0030] When the actual temperature of the air side outlet of the electrolytic cell reaches the actual temperature of the air side inlet of the electrolytic cell, the control center opens the purge pipeline, and the purge gas enters the water side heater for heating and then enters the water side inlet of the electrolytic cell to preheat the water side inlet of the electrolytic cell;

[0031] The control center opens the steam pipeline, and steam enters the water side inlet of the electrolyzer. The nitrogen flow rate is gradually reduced until it reaches 0, and the steam purge process is started;

[0032] When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the set value, the control center opens the hydrogen pipeline and introduces hydrogen to the water side inlet of the electrolyzer through the hydrogen pipeline to maintain a reducing atmosphere at the water side inlet of the electrolyzer;

[0033] When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the electrolysis temperature, the control center controls the electrolyzer to start working and continues to introduce hydrogen into the water side inlet of the electrolyzer;

[0034] The generated hydrogen enters the hydrogen storage tank. After the set time, the control center cuts off the hydrogen pipeline, starts the circulation pump, and sends the generated hydrogen into the electrolyzer through the second mixer.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1) The hydrogen production system provided by the present invention is provided with a purge pipeline. Before the system is started, the purge pipeline can purge the air in the water vapor pipeline to avoid explosion between the hydrogen generated by electrolysis and the air in the pipeline. The purge pipeline structure is reasonably arranged, and part of the water vapor pipeline is utilized to reduce the complexity of the overall system pipeline as much as possible. The temperature of the purge gas can be increased when passing through the water side heater, and the water side inlet of the electrolyzer is preheated, so that the water side inlet of the electrolyzer can be preheated during the early purge process. If preheating is not performed during the purge process, the water vapor preheating time is required. Therefore, the present application is conducive to shortening the startup time of the system.

[0037] 2) The present invention is provided with a hydrogen pipeline, the structure of the hydrogen pipeline is reasonably arranged, the hydrogen pipeline is connected to the first mixer, and passes through the water side heater, which is conducive to heating the hydrogen. The hydrogen is sent to the water side inlet of the electrolytic cell to prevent the electrolytic cell from being oxidized at high temperature, thereby affecting the performance.

[0038] 3) In the present invention, an air pipeline is provided at the anode of the electrolytic cell, and a water vapor pipeline is provided at the cathode. An air-side heat exchanger is provided in the air pipeline to exchange heat with the incoming cold air, thereby improving energy utilization. Simultaneous heat exchange is performed on both sides of the air pipeline and the water vapor pipeline, respectively, to avoid safety issues caused by cross heat exchange.

[0039] 4) A second mixer is provided in the water vapor pipeline of the present invention. The hydrogen generated at the hydrogen outlet of the electrolyzer can be fed into a hydrogen storage tank or fed into the second mixer through a circulation pump. The generated hydrogen is then fed into the water side inlet of the electrolyzer to maintain a reducing atmosphere at the cathode of the electrolyzer.

[0040] 5) The working method of the hydrogen production system in the present invention includes opening the air pipeline to increase the temperature at the air side inlet of the electrolyzer, introducing a purge gas to preheat the water side inlet of the electrolyzer to prevent water vapor from condensing into liquid water after entering, opening the water vapor pipeline to purge water vapor to further increase the temperature of the water side inlet of the electrolyzer, and then introducing hydrogen through the hydrogen pipeline to prevent the electrolyzer from oxidizing at high temperature and thus affecting performance, thereby gradually achieving safe startup of the hydrogen production system without causing fuel cell stack degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0042] Figure 1 This is a structural diagram of a fuel cell hydrogen production system in Example 1 of the present invention.

[0043] Figure 2 This is a structural diagram of a fuel cell hydrogen production system in Example 2 of the present invention. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0045] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly indicated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprising" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations;

[0046] As introduced in the background technology, in the prior art, a purge gas is separately provided in the hydrogen production system, and the purge gas is directly preheated with water vapor after purging, which results in a long preheating time and a long startup time for the entire system. In order to solve the above technical problems, the present invention proposes a fuel cell hydrogen production system.

[0047] Explanation of terms:

[0048] An MFC (Mass Flow Controller) is a device used to precisely control the flow of gases or liquids. It is widely used in industrial and scientific research fields requiring high-precision flow control. A sensor measures the mass flow rate of the fluid, and a controller adjusts an actuator (such as a valve) to achieve precise flow control. Its operating principle is based on a thermal flow sensor, which measures flow by detecting changes in gas temperature, thereby controlling valve opening.

[0049] Circulation pump: A device used to drive a fluid (such as liquid or gas) to circulate in a closed system. Its main function is to provide power to circulate the fluid in the system continuously to achieve purposes such as heat exchange, pressure maintenance or material transportation.

[0050] Electrolyzer: An electrolyzer is a device used to break down chemical compounds into their basic components through electrolysis. It primarily consists of a container, two electrodes (anode and cathode), and an electrolyte. When an electric current passes through the electrolyte, redox reactions occur on the anode and cathode surfaces, breaking down the chemical compounds.

[0051] Example 1

[0052] In a typical embodiment of the present invention, referring to Figure 1 As shown, a fuel cell hydrogen production system includes an electrolyzer, the air side inlet of the electrolyzer is connected to an air pipeline, an air side heater is provided in the air pipeline, the water side inlet of the electrolyzer is connected to a water vapor pipeline, a water side heat exchanger and a water side heater are provided in the water vapor pipeline, the hydrogen outlet of the electrolyzer is connected to the water side heat exchanger to exchange heat with the generated hydrogen, a first mixer is provided in the water vapor pipeline, a purge pipeline and a hydrogen pipeline are respectively connected to the first mixer so that the purge gas and hydrogen can be respectively fed into the water side inlet of the electrolyzer, and the purge gas in the purge pipeline passes through the water side heater and enters the water side inlet of the electrolyzer for preheating.

[0053] Among them, the air pipeline includes an air supply mechanism, an air-side heat exchanger and an air-side heater connected in sequence. The air supply mechanism is a fan. The air-side heater is connected to the air-side inlet of the electrolytic cell. The air-side outlet of the electrolytic cell is connected to the air-side heat exchanger to preheat the cold air. When the air-side heater in the air pipeline is turned on, the gas at the air-side inlet of the electrolytic cell can be heated, so that the temperature at the air-side inlet of the electrolytic cell reaches the set requirement, and there will be no cross-heat exchange with the pipeline on the cathode side of the electrolytic cell, so that the two sides of the electrolytic cell can exchange heat together, thereby improving safety.

[0054] Specifically, a first valve and a first flowmeter are set in the air pipeline, a second valve and a second flowmeter are set in the water vapor pipeline, a third valve and a third flowmeter are set in the purge pipeline, and a fourth valve and a fourth flowmeter are set in the hydrogen pipeline. The first flowmeter is the air MFC, the second flowmeter is the water vapor MFC, the third flowmeter is the nitrogen MFC, and the fourth flowmeter is the hydrogen MFC.

[0055] In this embodiment, a first one-way valve is provided in the steam pipeline between the first mixer and the steam MFC, the purge pipeline is a nitrogen purge pipeline for blowing out nitrogen, a second one-way valve is provided in the purge pipeline, and a third one-way valve is provided in the hydrogen pipeline between the first mixer and the hydrogen MFC to prevent backflow of the corresponding gas.

[0056] In addition, the air pipeline also includes a second mixer, which is arranged between the water side heater and the electrolyzer. The hydrogen outlet of the electrolyzer is connected to the condenser after passing through the water side heat exchanger. The condenser is connected to the gas-liquid separator, and the gas-liquid separator separates water and hydrogen.

[0057] Specifically, the water side heater and the air side heater are both electric heaters, which are connected to a control center, which may be a PLC controller or other types of controllers; the first mixer and the second mixer are both existing mixers.

[0058] It should be noted that temperature sensors are respectively provided at the air side inlet of the electrolyzer (anode inlet of the electrolyzer), the air side outlet of the electrolyzer (anode outlet of the electrolyzer), the hydrogen outlet of the electrolyzer (cathode outlet of the electrolyzer), and the water side inlet of the electrolyzer (cathode inlet of the electrolyzer). The temperature sensors are connected to the control center, and the control center is separately connected to the first valve, the second valve, the third valve and the fourth valve, and the control center is separately connected to the air MFC, the nitrogen MFC, the hydrogen MFC and the water vapor MFC.

[0059] The main working process on the water side is as follows: open the second valve, the water vapor flows through the water side heat exchanger and the water side heater to heat up to the required temperature range at the electrolytic cell inlet, enters the electrolytic cell for electrolysis, and the electrolytic cell produces a mixture of hydrogen and water vapor, which is cooled by the water side heat exchanger and the condenser, and the water is discharged by the gas-liquid separator to obtain the separated hydrogen product.

[0060] The main working process on the air side is: open the first valve, air is pumped in through the fan, first preheated by the air side heat exchanger, then heated to the required temperature range of the electrolyzer inlet by the air side heater, and enters the electrolyzer. The hot air at the hydrogen outlet of the electrolyzer enters the hot side of the air side heat exchanger, is preheated as cold air, and then discharged from the system.

[0061] This embodiment also provides a working method of a fuel cell hydrogen production system, including the following contents:

[0062] First, determine the current system status. If the system was shut down due to a fault during the last operation, the system cannot be started directly. You need to clear the triggered fault and determine whether the system is in a locked state. If the system is in a locked state, you need to manually clear this state to ensure that the system is in a normal state and start up to protect the system.

[0063] Before the system starts heating, first open the third valve, and control the nitrogen flow rate x1 by adjusting the opening of the nitrogen MFC. After maintaining this flow rate for t1 time, close the nitrogen MFC and the third valve to complete the nitrogen purge before startup, exhaust the remaining component gases in the system pipeline and replace them with nitrogen to ensure safety during startup;

[0064] When the system receives the start command, first, the fan runs, the first valve opens, and cold air flows into the air-side heat exchanger. However, since there is no heat source on the hot side of the air-side heat exchanger at this time, the air-side heat exchanger is equivalent to a pipeline. When the air-side MFC detects that the actual air volume is greater than 0 and lasts for t2 time, it ensures that there is medium flow in the air-side heater, maintains a constant flow rate x2 on the air side, and the air enters the air-side heater and sets the air-side heater outlet temperature T1 (i.e., the required value of the electrolyzer air-side inlet temperature). The cold air flows through the air-side heater, causing the air entering the electrolyzer air-side inlet to heat up. The heated hot air enters the hot side of the air-side heat exchanger, and the air-side heat exchanger works to preheat the cold air at the fan inlet, thereby increasing the air-side heater inlet temperature. The air circulates and heats up continuously until the actual temperature of the electrolyzer air-side inlet reaches the required value T1.

[0065] Among them, the air side heater adopts power control, and the given value is the electrolytic cell inlet temperature demand value T1. A temperature sensor is set at the electrolytic cell inlet, and the temperature sensor feeds back the actual temperature of the electrolytic cell inlet to the controller. The controller is connected to the air side heater, and the feedback value is the actual temperature of the electrolytic cell inlet T2. The controlled object is the air side heater power demand value Q1, until the actual temperature T2 of the electrolytic cell inlet is adjusted to be consistent with the demand value T1.

[0066] The air side inlet is continuously heated up. When the actual temperature at the air side outlet of the electrolyzer is ≥ T2, the third valve and the nitrogen MFC are opened again, and low-temperature nitrogen flows into the water side heat exchanger. However, since there is no heat source on the hot side of the water side heat exchanger at this time, the water side heat exchanger is equivalent to a pipeline. When the nitrogen MFC detects that the actual nitrogen amount is greater than 0 and lasts for t3 time, it ensures that there is medium flow in the water side heater. The nitrogen MFC is regulated to keep nitrogen flowing at a constant flow rate x3. The nitrogen enters the first mixer and then passes through the water side heat exchanger and the second mixer, flows through the water side heater and enters the electrolyzer. The outlet temperature of the water side heater is set to T3 (that is, the water side inlet temperature of the electrolyzer is T3, T3 = T2). The nitrogen circulates in it, causing the water side inlet of the electrolyzer to continuously heat up until the actual water side inlet temperature of the electrolyzer is ≥ T4, completing the nitrogen preheating.

[0067] Since the nitrogen preheating has been completed, the entire water side pipeline and components are preheated and heated. The water vapor will not condense into liquid water at low temperature, and no liquid water will enter the electrolyzer, causing the electrolyzer to attenuate. Open the second valve, adjust the water vapor MFC, start to introduce water vapor into the water side of the electrolyzer, gradually reduce the nitrogen flow rate until it is 0, and start the water vapor purge process. Pay attention to the nitrogen reduction rate and the water flow rate increase rate to ensure that the flow rate entering the water side heater is not less than x4, and at this time the water side heater is always enabled and maintains the water side heater outlet temperature T3 (T3 = T2), so that the water side inlet of the electrolyzer continues to heat up. When the actual temperature of the hydrogen outlet of the electrolyzer is ≥ T5, the water vapor purge is completed;

[0068] When the actual temperature of the hydrogen outlet of the electrolyzer is ≥T5, a certain amount of hydrogen needs to be introduced into the system to prevent the electrolyzer from oxidizing at high temperature and thus affecting performance. The amount of hydrogen introduced is determined by the hydrogen-water ratio and the water flow rate. The water-hydrogen ratio is set to a fixed value (such as 7:3), and the water vapor MFC is regulated to maintain the minimum steam flow rate x5. The hydrogen flow rate demand value x6 is calculated by the set water-hydrogen ratio and the minimum steam flow rate. The actual hydrogen flow rate is controlled by the hydrogen MFC to reach the demand value x6. At this time, in order to continue to heat up the system, the air side and water side inlet temperature demand T6 of the electrolyzer is increased (T6>T3=T2), the reducing atmosphere on the cathode side of the electrolyzer is maintained, and the hydrogen outlet temperature of the electrolyzer continues to rise to T7;

[0069] When the hydrogen outlet temperature of the electrolyzer is ≥T7, the system has the conditions for electrolysis, the DC power supply is enabled, and the hydrogen production x7 is set. At this time, the current has a demand value, and the electrolyzer begins to pull the current to electrolyze water to produce hydrogen. In order to maintain the reducing atmosphere of the electrolyzer cathode, hydrogen x8 still needs to be introduced into the system through the hydrogen MFC. x8 is calculated based on the set water-hydrogen ratio and water vapor flow rate, where the water vapor flow rate is calculated based on the water vapor utilization rate and the current setting value, and the current setting value is calculated based on the hydrogen production. As the electrolysis current is pulled, the electrolyzer power gradually increases until it is pulled to the required current, completing the system startup to electrolysis process.

[0070] Example 2

[0071] The difference between this embodiment and the first embodiment is that: Figure 2 As shown, the gas-liquid separator is connected to the hydrogen storage tank, the hydrogen storage tank is connected to the hydrogen pipeline, and the hydrogen storage tank is connected to the second mixer through a circulation pump.

[0072] The hydrogen production system provided in this embodiment has the same working process on the air side of the electrolyzer as that in the first embodiment, except that a hydrogen circulation device is added. The hydrogen obtained after the electrolysis product is cooled, cooled and dehydrated is divided into two parts. One part enters the hydrogen storage tank, and the other part enters the second mixer through a circulation pump and then enters the cathode of the electrolyzer to maintain a reducing atmosphere at the cathode of the electrolyzer.

[0073] The startup logic of the fuel cell hydrogen production system in this embodiment is exactly the same as that in the first embodiment before electrolysis, and the circulation pump is always in the off state before electrolysis. The control logic of the fuel cell hydrogen production system during electrolysis in this embodiment is as follows:

[0074] When the electrolytic cell temperature is ≥ T7, the system has the conditions for electrolysis, the DC power supply is enabled, and the hydrogen production is set to x7. At this time, the current has a demand value, and the electrolytic cell begins to pull the current to electrolyze water to produce hydrogen. However, since the current and electrolysis power are small at this time, the hydrogen flow rate generated is small. In order to maintain the reducing atmosphere of the electrolytic cell cathode, hydrogen still needs to be introduced into the system through the hydrogen MFC. The hydrogen flow rate is x8, which is calculated based on the set water-hydrogen ratio and water vapor flow rate. Among them, the water vapor flow rate is calculated based on the water vapor utilization rate and the current setting value. The current setting value is calculated based on the hydrogen production. As the electrolysis current is pulled, the electrolytic cell power gradually increases;

[0075] As the current is loaded, the amount of hydrogen produced by the electrolyzer increases, which is sufficient to meet the water-hydrogen ratio requirement. The fourth valve is closed to cut off the external supply of hydrogen. At the same time, the circulation pump is turned on. The speed of the circulation pump is controlled by the water-hydrogen ratio. The water vapor flow rate is calculated based on the water vapor utilization rate and the current setting value. The current is continued to be loaded to the current demand value to complete the system startup to electrolysis process.

[0076] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A fuel cell hydrogen production system, comprising an electrolyzer, characterized in that: The air side inlet of the electrolyzer is connected to the air pipeline, an air side heater is provided in the air pipeline, the water side inlet of the electrolyzer is connected to the steam pipeline, a water side heat exchanger and a water side heater are provided in the steam pipeline, the hydrogen outlet of the electrolyzer is connected to the water side heat exchanger to exchange heat for the generated hydrogen, a first mixer is provided in the steam pipeline, a purge pipeline and a hydrogen pipeline are respectively connected to the first mixer so that the purge gas and hydrogen can be respectively fed into the water side inlet of the electrolyzer, and the purge gas in the purge pipeline enters the water side inlet of the electrolyzer through the water side heater for preheating.

2. A fuel cell hydrogen production system according to claim 1, characterized in that: The air pipeline includes an air supply mechanism, an air side heat exchanger and the air side heater connected in sequence. The air side heater is connected to the air side inlet of the electrolytic cell, and the air side outlet of the electrolytic cell is connected to the air side heat exchanger to preheat the cold air.

3. A fuel cell hydrogen production system according to claim 1, characterized in that: Temperature sensors are respectively provided at each inlet and each outlet of the electrolytic cell, and the temperature sensors are connected to the control center. The controller adjusts the power of the air side heater and the water side heater according to the temperature information fed back by each temperature sensor.

4. A fuel cell hydrogen production system according to claim 3, characterized in that: The air pipeline is provided with a first valve and a first flow meter, the steam pipeline is provided with a second valve and a second flow meter, the purge pipeline is provided with a third valve and a third flow meter, and the hydrogen pipeline is provided with a fourth valve and a fourth flow meter; The first flow meter, the first valve, the second valve, the second flow meter, the third valve, the third flow meter, the fourth valve and the fourth flow meter are respectively connected to the control center.

5. A fuel cell hydrogen production system according to claim 1, characterized in that: The air pipeline also includes a second mixer, which is arranged between the water side heater and the electrolyzer. The hydrogen outlet of the electrolyzer is connected to the condenser after passing through the water side heat exchanger, and the condenser is connected to the gas-liquid separator.

6. A fuel cell hydrogen production system according to claim 5, characterized in that: The gas-liquid separator is communicated with the hydrogen storage tank, the hydrogen storage tank is communicated with the hydrogen pipeline, and the hydrogen storage tank is communicated with the second mixer through a circulation pump.

7. The operating method of a fuel cell hydrogen production system according to claim 4, characterized in that: Includes the following: The control center opens the air pipeline, and the cold air enters the air side heater to heat the cold air. The heated air enters the air side inlet of the electrolytic cell until the actual temperature of the air side inlet of the electrolytic cell reaches the required value of the air side inlet temperature of the electrolytic cell; When the actual temperature of the air side outlet of the electrolytic cell reaches the actual temperature of the air side inlet of the electrolytic cell, the control center opens the purge pipeline, and the purge gas enters the water side heater for heating and then enters the water side inlet of the electrolytic cell to preheat the water side inlet of the electrolytic cell; The control center opens the steam pipeline, and steam enters the water side inlet of the electrolyzer. The nitrogen flow rate is gradually reduced until it reaches 0, and the steam purge process is started; When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the set value, the control center opens the hydrogen pipeline and introduces hydrogen to the water side inlet of the electrolyzer through the hydrogen pipeline to maintain a reducing atmosphere at the water side inlet of the electrolyzer; When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the electrolysis temperature, the control center controls the electrolyzer to start working and continues to introduce hydrogen into the water side inlet of the electrolyzer.

8. The operating method of a fuel cell hydrogen production system according to claim 7, characterized in that: The control center sets the required value of the air side inlet temperature of the electrolytic cell. The temperature sensor at the air side inlet of the electrolytic cell obtains the actual temperature of the air side inlet of the electrolytic cell and sends it to the controller. The controller adjusts the power of the air side heater until the actual temperature of the air side inlet of the electrolytic cell reaches the required value of the air side inlet temperature of the electrolytic cell.

9. The operating method of a fuel cell hydrogen production system according to claim 7, characterized in that: Before the air pipeline is opened, the purge pipeline is opened first, so that the purge gas enters the water side inlet of the electrolyzer through the first mixer to ensure safety during startup.

10. The operating method of a fuel cell hydrogen production system according to claim 6, characterized in that: Includes the following: The control center opens the air pipeline, and the cold air enters the air side heater to heat the cold air. The heated air enters the air side inlet of the electrolytic cell until the actual temperature of the air side inlet of the electrolytic cell reaches the required value of the air side inlet temperature of the electrolytic cell; When the actual temperature of the air side outlet of the electrolytic cell reaches the actual temperature of the air side inlet of the electrolytic cell, the control center opens the purge pipeline, and the purge gas enters the water side heater for heating and then enters the water side inlet of the electrolytic cell to preheat the water side inlet of the electrolytic cell; The control center opens the steam pipeline, and steam enters the water side inlet of the electrolyzer. The nitrogen flow rate is gradually reduced until it reaches 0, and the steam purge process is started; When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the set value, the control center opens the hydrogen pipeline and introduces hydrogen to the water side inlet of the electrolyzer through the hydrogen pipeline to maintain a reducing atmosphere at the water side inlet of the electrolyzer; When the temperature at the hydrogen outlet of the electrolyzer is greater than or equal to the electrolysis temperature, the control center controls the electrolyzer to start working and continues to introduce hydrogen into the water side inlet of the electrolyzer; The generated hydrogen enters the hydrogen storage tank. After the set time, the control center cuts off the hydrogen pipeline, starts the circulation pump, and sends the generated hydrogen into the electrolyzer through the second mixer.

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