Mobile standby power generation system based on methanol-to-hydrogen fuel cell system and control method thereof

Abstract

The invention discloses a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system and a control method thereof. The technical problems that a combustion heating system needs to be arranged for existing methanol hydrogen production, the structure is complex, the risk is high, and energy supply cannot be adapted to an outdoor mobile power generation scene are mainly solved. The system comprises a methanol material tank, a pure water material tank, an evaporator, a gasification superheater, a methanol water reforming reactor, an air cooler, a gas-liquid separator, a PSA (Pressure Swing Adsorption) tower for separating desorbed gas and pure hydrogen, a methanol part catalytic oxidation reactor and a hydrogen fuel electric pile taking hydrogen output by the PSA tower as a material source, wherein the evaporator, the gasification superheater, the methanol water reforming reactor, the air cooler and the gas-liquid separator are sequentially connected to the downstream of a mixing tank; the inverter and the storage battery pack are electrically connected with the hydrogen fuel electric pile in sequence; a first heat exchanger is arranged in a pipeline between the mixing tank and the evaporator, and a second heat exchanger is arranged in a pipeline between the evaporator and the gasification superheater. The power generation system has the advantages of high heat recovery efficiency, high raw material utilization rate, low system energy consumption and the like.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen energy technology, and specifically to a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system and a control method thereof. Background Art

[0002] Hydrogen is considered an ideal clean energy source due to its high efficiency, cleanliness and high energy density. At present, the main method of hydrogen production is still based on fossil energy, including coking coal gasification, natural gas reforming, methanol reforming and water electrolysis. Among them, methanol hydrogen production is widely used in industrial production due to its simple raw material source, low reaction requirements and high conversion efficiency. Hydrogen fuel cells are based on the reverse reaction of water electrolysis, which can directly convert the chemical energy of hydrogen and oxygen into electrical energy. Compared with traditional diesel generators, they have the advantages of quiet operation, efficient process and zero emissions.

[0003] Among them, the mainstream methods of methanol hydrogen production include methanol steam reforming hydrogen production, methanol cracking hydrogen production, and methanol partial oxidation hydrogen production. Methanol steam reforming hydrogen production is to mix methanol and desalted water in a certain proportion, enter the gasification superheater for gasification and superheat to the required temperature, and complete the two reactions of gas-phase catalytic cracking and conversion under the action of the catalyst to generate conversion gas containing CO2, H2, and CO; the conversion gas is cooled by the heat exchanger and condenser to purify and recover the unreacted methanol, and finally enter the pressure swing adsorber to obtain high-purity hydrogen. In addition, methanol partial oxidation hydrogen production uses air as the oxygen source and utilizes the incomplete combustion reaction between oxygen and methanol to prepare hydrogen; the methanol partial oxidation system is heated by methanol combustion and hydrogen is supplied by steam reforming; all energy in the system comes from methanol, and all substances come from methanol, water and air. Methanol, water and air are preheated from room temperature to a certain temperature through the evaporator, and then enter the reactor for reaction. The obtained product gas is discharged after recovering heat through the heat exchanger, and enters the pressure swing adsorber to remove impurities to obtain high-purity hydrogen.

[0004] The existing methanol-to-hydrogen technology requires the heat required for the hydrogen production reaction to be supplied by the fuel combustion of the combustion heating system, and the methanol-to-hydrogen equipment needs to be equipped with a thermal oil heating system to provide heat for the vaporization and reaction of the hydrogen production raw materials through the thermal oil. However, due to the large size and complex structure of the combustion heating system, which is an open flame equipment, there are certain safety risks.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] In view of at least one of the above technical problems, the present disclosure provides a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system and a control method thereof; it mainly solves the technical problems that the existing methanol-to-hydrogen production requires the setting of a combustion heating system, which results in a complex structure with high risks and cannot adapt to energy supply in outdoor mobile power generation scenarios.

[0007] According to one aspect of the present disclosure, a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system is provided, which includes a methanol tank and a pure water tank respectively connected to a mixing tank through a methanol pump or a pure water pump for correspondingly conveying methanol and pure water, an evaporator, a gasification superheater, a methanol-water reforming reactor, an air cooler, a gas-liquid separator and a PSA adsorption tower for separating desorption gas and pure hydrogen, which are sequentially connected downstream of the mixing tank, a methanol partial catalytic oxidation reactor connected to the methanol tank and the desorption gas outlet of the PSA adsorption tower and correspondingly connected to the air cooler for output, a hydrogen fuel cell stack using the hydrogen output of the PSA adsorption tower as a feed source, and an inverter and a battery pack electrically connected to the hydrogen fuel cell stack in sequence; a first heat exchanger for exchanging heat with the high temperature in the methanol partial catalytic oxidation reactor is provided in the pipeline between the mixing tank and the evaporator, and a second heat exchanger for exchanging heat with the high temperature in the methanol-water reforming reactor is provided in the pipeline between the evaporator and the gasification superheater.

[0008] In some embodiments of the present disclosure, the mobile backup power generation system further includes a blower for delivering air to the methanol partial catalytic oxidation reactor and the hydrogen fuel cell stack.

[0009] In some embodiments of the present disclosure, an air outlet of the blower is connected to an air-cooled heat exchanger for exchanging heat with combustion flue gas of the hydrogen fuel cell stack.

[0010] In some embodiments of the present disclosure, the liquid outlet of the gas-liquid separator is correspondingly connected to the pure water tank.

[0011] In some embodiments of the present disclosure, a gas-liquid separation buffer tank is provided in the pipeline between the gas-liquid separator and the pure water tank.

[0012] In some embodiments of the present disclosure, a mixed hydrogen buffer tank is provided in the pipeline between the gas-liquid separator and the PSA adsorption tower, and a desorption gas buffer tank and a pure hydrogen buffer tank are provided in the desorption gas outlet pipeline and the pure hydrogen outlet pipeline of the PSA adsorption tower, respectively.

[0013] In some embodiments of the present disclosure, the PSA adsorption tower series is provided with a plurality of adsorption towers, and at least one adsorption tower is provided with a molecular sieve adsorbent.

[0014] According to another aspect of the present disclosure, a method for controlling a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system is provided, which is implemented based on the above-mentioned mobile standby power generation system, and correspondingly adjusts the methanol pump and the pure water pump to control the methanol mass percentage in the methanol-water solution in the mixing tank to be 50-70%; controls the reaction temperature in the methanol-water reforming reactor to be 200-300°C; and regulates the reaction temperature of the hydrogen fuel cell stack to be 75-95°C.

[0015] In some embodiments of the present disclosure, the methanol-water reforming reactor is loaded with a Cu-Zn-Al2O3 catalyst, and the reaction temperature is controlled to be 220-250°C.

[0016] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: 1. Through the methanol-water reforming reaction and hydrogen production coupled with methanol partial catalytic oxidation technology, the first heat exchanger is used to recover the heat generated by the partial catalytic oxidation reaction and use it for the methanol-water reforming reaction. There is no need to set up an additional combustion heating system, thereby reducing equipment costs and improving heat utilization.

[0017] 2. The crude hydrogen product obtained by the reforming reaction of methanol-water solution is heat exchanged with the feed through the second heat exchanger, and then enters the air cooler for cooling, thereby reducing the cooling consumption of the crude hydrogen product and improving the heat utilization rate.

[0018] 3. The synthesis gas is purified by PSA purification technology, and the purified analytical gas is transported back to the partial catalytic oxidation reactor, thereby making full use of the heat energy of CO, CH4 and other unreacted substances in the analytical gas.

[0019] 4. The hot exhaust gas generated by the hydrogen fuel cell stack exchanges heat with the air output by the blower through an air-cooled heat exchanger, thereby recovering the heat energy in the exhaust gas of the hydrogen fuel cell stack and further improving the energy utilization rate of the system.

[0020] 5. The unreacted water separated by the gas-liquid separator is circulated to the pure water tank through a pipeline for secondary utilization, which can reduce the pure water consumption in the process of methanol to hydrogen.

[0021] 6. The methanol hydrogen production unit and the fuel cell power generation unit use independent PLC controllers, so that each unit can operate independently, avoiding the impact of the operation of the PSA purification unit and other subsystems, thereby improving system utilization and enriching the diversity of system operation.

[0022] 7. Combining methanol hydrogen purification process with PEM fuel cell power generation to realize mobile standby power generation system, only a certain amount of methanol and pure water are needed to realize standby power generation function, which can be used for power generation in remote areas such as islands and mines. The startup time of the whole system is short (≤30min), and a battery pack is installed to realize energy storage standby. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural principle block diagram of a mobile standby power generation system in one embodiment of the present application. DETAILED DESCRIPTION

[0024] The terms "first", "second", etc. mentioned in this application are used to distinguish the objects described and do not have any order or technical meaning. The terms "connection" and "coupling" mentioned in this application include direct and indirect connections (couplings) unless otherwise specified. The programs involved or relied upon in the following embodiments are all conventional or simple programs in the field of technology, and those skilled in the art can make conventional choices or adaptive adjustments based on specific application scenarios. The devices involved in the following embodiments, unless otherwise specified, are all conventional commercially available products.

[0025] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] This example discloses a mobile standby power generation system based on a methanol hydrogen production fuel cell system, which includes a methanol hydrogen production unit, a PSA purification unit, a fuel cell power generation unit, and an electrical control unit. Among them, the methanol hydrogen production unit adopts methanol aqueous solution reforming coupled with partial catalytic oxidation technology to produce hydrogen to improve product and heat utilization; the PSA purification unit adopts PSA pressure swing adsorption purification to obtain pure hydrogen as the hydrogen source of the fuel cell power generation unit, and burns and generates electricity based on the PEM fuel cell system. In addition, in this embodiment, the methanol hydrogen production unit and the fuel cell power generation unit are respectively controlled by independent PLC electrical controls, so that the methanol hydrogen production unit and the fuel cell power generation unit can be operated separately, and are not affected by the operation of the PSA purification unit and other parts, thereby improving the system utilization rate, enriching the application scenarios of this system, and realizing the diversification of operation.

[0027] See also Figure 1 The methanol hydrogen production unit includes a methanol material tank and a pure water material tank. The two tanks respectively contain methanol raw materials and pure water raw materials required for the methanol hydrogen production reaction. In this embodiment, the methanol material tank and the pure water material tank are 304 stainless steel tanks, and the two tanks are respectively equipped with magnetic flap level gauges. The magnetic flap level gauges are used to monitor the liquid level height in the corresponding tanks so that timely replenishment can be made when the material liquid is insufficient to avoid affecting the normal progress of the subsequent hydrogen production reaction.

[0028] During the hydrogen production operation, methanol and pure water need to be mixed for reaction. In this embodiment, a mixing tank is set downstream of the methanol tank and the pure water tank. The methanol tank and the pure water tank are connected to the mixing tank through a methanol pump or a pure water pump, respectively, to pump the corresponding mass of liquid into the mixing tank according to the design requirements. At the same time, this example also discloses a control method for a mobile standby power generation system, which controls the conduction and liquid metering of the methanol pump through the PLC controller of the methanol hydrogen production unit, so that the mass ratio of methanol in the methanol and pure water mixed solution is 50% to 70%. Among them, in order to achieve the measurement of methanol mass, the methanol pump in this example uses a stainless steel diaphragm metering pump; and the mixing tank body is made of 304 stainless steel, and a magnetic flap level gauge for monitoring the liquid level height in the tank body and an agitator for achieving full mixing of methanol and pure water are set at the mixing tank body.

[0029] After the methanol and pure water are fully stirred and mixed in the mixing tank, the mixed liquid is pumped into the evaporator and the gasification superheater in sequence through the feed pump. The mixed liquid changes from liquid to saturated gas in the evaporator and the gasification superheater, and enters the methanol water reforming reactor after gasification to react and produce hydrogen under the action of the catalyst. At the same time, in order to improve the thermal utilization efficiency of the system and the utilization efficiency of the reaction products, in this embodiment, the purpose of hydrogen production is achieved by coupling the methanol water reforming reaction with the methanol partial catalytic oxidation reaction, see Figure 1 The mobile standby power generation system also includes a methanol partial catalytic oxidation reactor. The methanol feed tank pumps methanol into the mixing tank through a methanol pump, and at the same time, the methanol is pumped into the methanol partial catalytic oxidation reactor through a methanol pump. In the methanol partial catalytic oxidation reactor, methanol and air react with H2, CH4, CO, CO2 and other products purified by the PSA purification unit to produce hydrogen. During the reaction, a large amount of heat is generated. In order to achieve effective utilization of the heat, see Figure 1 A first heat exchanger is arranged between the mixing tank and the evaporator. The heat generated in the partial catalytic oxidation reaction of methanol is obtained through the first heat exchanger, and heat is exchanged with the liquid methanol-water mixture flowing in the pipeline between the feed pump and the evaporator to increase the inlet temperature of the evaporator, thereby realizing heat utilization and reducing the energy consumption of the evaporator and the gasification superheater.

[0030] In addition, in this embodiment, in order to realize the methanol water reforming reaction, a certain amount of reforming catalyst is stored in the methanol water reforming reactor, and the reaction temperature in the reactor is controlled to be in the range of 200°C to 300°C. Specifically in this example, the catalyst is Cu-Zn-Al2O3 medium-temperature reforming catalyst, and the reaction temperature in the reactor is controlled to be 220°C to 250°C. Thus, the methanol water solution reacts under the action of the catalyst and generates synthesis gas. In this example, the components of the synthesis gas are H2≥74%, CO2≤24%, CO≤1%, CH4≤0.5%, and H20≤0.5%. See Figure 1 Considering that a large amount of heat will also be generated during the reaction in the methanol-water reforming reactor, in this example, the outlet temperature of the methanol-water reforming reactor is about 200°C. In order to realize the recovery and utilization of the heat, a second heat exchanger is set between the evaporator and the gasification superheater. The heat generated during the reaction in the methanol-water reforming reactor is obtained through the second heat exchanger, and heat is exchanged with the gas-liquid mixture that is not fully vaporized in the pipeline between the evaporator and the gasification superheater, thereby increasing the inlet material temperature of the gasification superheater, thereby realizing the recovery and utilization of heat at the methanol-water reforming reactor and reducing the energy consumption of the gasification superheater.

[0031] The reactants in the methanol-water reforming reactor and the methanol partial catalytic oxidation reactor are respectively cooled in the air cooler after heat recovery through the second heat exchanger and the first heat exchanger. The cooled synthesis gas enters the gas-liquid separator for gas-liquid separation, thereby separating the water in the gas-liquid mixture, and the methanol hydrogen production unit outputs synthesis gas containing hydrogen. Among them, in order to achieve the recycling of the separated water, in this embodiment, the methanol hydrogen production unit also includes a gas-liquid separation buffer tank, and the water separated by the gas-liquid separator is transported to the gas-liquid separation buffer tank through a pipeline for buffering, and the gas-liquid separation buffer tank is connected to the pure water tank through a pipeline, thereby achieving the recycling of water. In this example, a magnetic flap level gauge is also provided at the gas-liquid separation buffer tank to monitor the liquid level height in the gas-liquid separation tank. And in this example, in order to reduce the working pressure of the subsequent PSA purification unit, see Figure 1 The synthesis gas separated by the gas-liquid separator is transported to the mixed hydrogen buffer tank for buffering.

[0032] The synthesis gas is obtained through the methanol-water reforming reaction and the methanol partial catalytic oxidation reaction in the methanol hydrogen production unit. However, the synthesis gas contains multiple components. In order to obtain pure hydrogen, in this embodiment, the synthesis gas is input into the PSA purification unit. Figure 1, the PSA purification unit includes 4 to 6 PSA adsorption towers, which are sequentially adsorbed, uniformly lowered, forwardly released, reversely released, flushed, uniformly raised, and finally raised; thus, the synthesis gas in the mixed hydrogen buffer tank is transported to the PSA adsorption tower through a pipeline for adsorption purification. In this embodiment, the adsorption tower is filled with molecular sieve adsorbent, and it is ensured that at least one adsorption tower in each adsorption tower is in an adsorption state at the same time. The continuous operation of the equipment is achieved through a program-controlled valve connected to the PLC controller corresponding to the PSA adsorption tower. After the synthesis gas is purified by PSA, H2≥99.99%, CO≤0.2% in the purified gas components, and the temperature is less than or equal to 40°C. Among them, in this embodiment, in order to realize the storage buffering of the purified hydrogen, the mobile standby power generation system includes a pure hydrogen buffer tank, and the pure hydrogen purified by PSA enters the pure hydrogen buffer tank for buffering and storage to ensure the stability of the subsequent hydrogen inlet of the hydrogen fuel cell stack and the normal operation of the hydrogen fuel cell stack.

[0033] In addition, the PSA purification unit will produce analysis gas including H2, CH4, CO, and CO2 while obtaining pure hydrogen through operations such as adsorption. In order to fully utilize the analysis gas of the purified product, in this embodiment, the analysis gas is transported to the methanol partial catalytic oxidation reactor to participate in the partial catalytic oxidation reaction. At the same time, in order to ensure the stability of the intake gas, in this example, a analysis gas buffer tank is set between the PSA adsorption tower and the methanol partial catalytic oxidation reactor to play a storage buffer role for the analysis gas.

[0034] The fuel cell power generation unit includes a hydrogen fuel cell stack, which uses the hydrogen in the pure hydrogen buffer tank as a source of material to generate electricity. In this embodiment, the hydrogen fuel cell stack is a PEM fuel cell stack, and the reaction temperature of the fuel cell stack is correspondingly regulated to be 75-95°C. In this example, the reaction temperature is controlled to be 80°C. In addition, the hydrogen fuel cell stack in this example uses an injector to inject hydrogen to improve the efficiency of fuel cell power generation. Since the output of the hydrogen fuel cell stack is about 500V DC, in order to meet the AC power demand, see Figure 1 The output of the hydrogen fuel cell stack is connected to the inverter, and the DC / AC module converts the DC power into 380V AC power. Considering the fluctuation of actual power consumption, in order to fully utilize the generated power, the fuel cell power generation unit includes a battery pack, which stores power and avoids power waste.

[0035] In addition, considering that the hydrogen fuel cell and the methanol partial catalytic oxidation reactor require a certain amount of air supply during the working reaction, for this reason, see Figure 1The backup power generation system includes a blower, through which air is delivered to the hydrogen fuel cell stack and the methanol partial catalytic oxidation reactor. When combustion and power generation are carried out in the hydrogen fuel cell stack, a lot of heat will be generated. In order to fully recycle and utilize the heat, the air outlet of the blower is connected to an air-cooled heat exchanger, and the blown air exchanges heat with the exhaust gas discharged from the hydrogen fuel cell stack through the air-cooled heat exchanger, thereby increasing the air temperature entering the hydrogen fuel cell stack and the methanol partial catalytic oxidation reactor, and realizing heat recovery.

[0036] Although some preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0037] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A mobile standby power generation system based on a methanol-to-hydrogen fuel cell system, characterized in that: The invention comprises a methanol feed tank and a pure water feed tank respectively connected to a mixing tank through a methanol pump or a pure water pump for correspondingly conveying methanol and pure water, an evaporator, a gasification superheater, a methanol water reforming reactor, an air cooler, a gas-liquid separator and a PSA adsorption tower for separating desorption gas and pure hydrogen, which are sequentially connected downstream of the mixing tank, a methanol partial catalytic oxidation reactor connected to the methanol feed tank and the desorption gas outlet of the PSA adsorption tower and correspondingly connected to the air cooler for output, a hydrogen fuel cell stack using the hydrogen output of the PSA adsorption tower as a feed source, and an inverter and a battery group electrically connected to the hydrogen fuel cell stack in sequence; a first heat exchanger for exchanging heat with the high temperature in the methanol partial catalytic oxidation reactor is provided in the pipeline between the mixing tank and the evaporator, and a second heat exchanger for exchanging heat with the high temperature in the methanol water reforming reactor is provided in the pipeline between the evaporator and the gasification superheater.

2. The mobile standby power generation system according to claim 1, characterized in that: It also includes a blower for delivering air to the methanol partial catalytic oxidation reactor and the hydrogen fuel cell stack.

3. The mobile standby power generation system according to claim 2, characterized in that: The air outlet of the blower is correspondingly connected to an air-cooled heat exchanger for exchanging heat with the combustion flue gas of the hydrogen fuel cell stack.

4. The mobile standby power generation system according to claim 1, characterized in that: The liquid outlet of the gas-liquid separator is correspondingly connected to the pure water tank.

5. The mobile standby power generation system according to claim 4, characterized in that: A gas-liquid separation buffer tank is provided in the pipeline between the gas-liquid separator and the pure water tank.

6. The mobile standby power generation system according to claim 1, characterized in that: A mixed hydrogen buffer tank is provided in the pipeline between the gas-liquid separator and the PSA adsorption tower, and a desorption gas buffer tank and a pure hydrogen buffer tank are respectively provided in the desorption gas outlet pipeline and the pure hydrogen outlet pipeline of the PSA adsorption tower.

7. The mobile standby power generation system according to claim 1, characterized in that: The PSA adsorption tower series is provided with a plurality of adsorption towers, and at least one adsorption tower is provided with a molecular sieve adsorbent.

8. A control method for a mobile standby power generation system based on a methanol-to-hydrogen fuel cell system, characterized in that: It is implemented based on the mobile standby power generation system described in claim 1, and the methanol pump and the pure water pump are adjusted accordingly to control the methanol mass percentage in the methanol-water solution in the mixing tank to be 50-70%; the reaction temperature in the methanol-water reforming reactor is controlled to be 200-300°C; and the reaction temperature of the hydrogen fuel cell stack is regulated to be 75-95°C.

9. The mobile standby power generation system control method according to claim 8, characterized in that: The methanol-water reforming reactor is filled with Cu-Zn-Al2O3 catalyst, and the reaction temperature is controlled to be 220-250°C.

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