Ammonia hydrogen production fuel cell-storage battery hybrid power supply system

Abstract

The invention discloses an ammonia hydrogen production fuel cell-storage battery hybrid power supply system which comprises a liquid ammonia source, a gasifier, a first heat exchanger, an ammonia decomposition reactor, a membrane separation purifier, a pure hydrogen collector, a fuel cell and a power supply unit. The system preheats ammonia gas through the first heat exchanger, and the energy efficiency is improved; ammonia gas in the ammonia decomposition reactor is decomposed into hydrogen and nitrogen, high-temperature product mixed gas serves as a heat source of the first heat exchanger, and energy is recycled; the membrane separation purifier adopts a selective hydrogen permeation membrane to efficiently separate hydrogen, so that the hydrogen purity is improved; the power supply unit comprises a storage battery and a super capacitor which are arranged in parallel, the fuel cell can charge the storage battery and the super capacitor, and the storage battery can charge the super capacitor, so that the stability and the reliability of power supply are improved, and complementary utilization of energy is realized; and stable power output can be provided under various working conditions.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen energy technology, and in particular to an ammonia-to-hydrogen fuel cell-battery hybrid power supply system. Background Art

[0002] With the continuous growth of energy demand and the increasingly severe environmental problems, the search for clean and efficient energy solutions has become a hot topic of global concern. Hydrogen energy, as a clean and efficient energy carrier, has the advantages of high energy density and no pollution emissions, and is considered to be an important part of the future energy system. However, traditional hydrogen production methods such as steam reforming have problems such as high energy consumption and large carbon emissions, which limit their large-scale application.

[0003] In this context, ammonia hydrogen production technology has gradually become a research hotspot due to its advantages such as wide sources of raw materials (such as industrial waste gas, agricultural waste, etc. can be converted into ammonia), convenient storage and transportation (liquid ammonia is easy to store and transport), and flexible and controllable hydrogen production process. Ammonia can generate hydrogen and nitrogen through thermal decomposition reaction, and the reaction is reversible, which makes it easy to adjust the reaction conditions to achieve efficient hydrogen production.

[0004] Among renewable liquid fuels, ammonia has a high mass and volume hydrogen density, which is much higher than that of liquid hydrogen systems, and its storage conditions are mild. Fuel cells have the advantages of high efficiency and high power. Therefore, using an ammonia hydrogen production system as a hydrogen source to drive hydrogen-oxygen fuel cells has high technical value, especially for large electric-driven mobile tools. However, mobile tools such as trucks and ships require faster start-stop responses, but ammonia hydrogen production systems require a long start-up time. Therefore, a single ammonia hydrogen production system seriously affects the smoothness of downstream load operation. Therefore, how to couple the characteristics of the ammonia hydrogen production system with fuel cells and necessary auxiliary power supplies to shorten the start-stop time and increase the smoothness of downstream load units is a technical requirement that needs to be broken through in the field of hydrogen energy applications. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an ammonia-to-hydrogen fuel cell-battery hybrid power supply system, which realizes the stable preparation, efficient utilization and flexible energy storage of hydrogen by integrating key components such as ammonia decomposition hydrogen production, fuel cells, batteries and supercapacitors. Among them, the ammonia decomposition hydrogen production subsystem improves the system startup speed, as well as the yield and purity of hydrogen by optimizing the processes of ammonia gasification, heat exchange, decomposition, and purification; the fuel cell uses the hydrogen produced by the ammonia-to-hydrogen system as fuel to react with air to generate electricity; the battery and supercapacitor are energy storage elements with different characteristics, which complement each other and jointly balance the energy supply and demand of the power supply system, thereby improving the stability and reliability of the system.

[0006] The present invention adopts the following technical solution:

[0007] An ammonia-to-hydrogen fuel cell-battery hybrid power supply system, comprising a liquid ammonia source, a vaporizer, a first heat exchanger, an ammonia decomposition reactor, a membrane separation purifier, a pure hydrogen collector, a fuel cell and a power supply unit; the liquid ammonia source is connected to the vaporizer for gasifying liquid ammonia into ammonia; the first heat exchanger comprises a first heat exchange ammonia channel and a first heat exchange product gas channel, the ammonia decomposition reactor comprises an ammonia decomposition reaction ammonia channel and an ammonia decomposition reaction flue gas channel, the membrane separation purifier comprises a purified hydrogen channel and an unpurified hydrogen channel, the outlet of the vaporizer is connected to the inlet of the first heat exchange ammonia channel, the outlet of the first heat exchange ammonia channel is connected to the inlet of the ammonia decomposition reaction ammonia channel, and the ammonia after heat exchange by the first heat exchanger is passed into the The ammonia decomposition reactor decomposes ammonia; the outlet of the ammonia decomposition reaction ammonia channel is connected to the inlet of the first heat exchange product gas channel, and the outlet of the first heat exchange product gas channel is connected to the inlet of the purified hydrogen channel. The product mixed gas decomposed by the ammonia decomposition reactor is used as the heat exchange medium of the first heat exchanger and is heat exchanged with the ammonia passing through the first heat exchange ammonia channel, and then passed into the membrane separation purifier for hydrogen purification; the outlet of the purified hydrogen channel is connected to the inlet of the pure hydrogen collector, and the purified hydrogen is cooled, collected and stored. The outlet of the pure hydrogen collector is connected to the negative electrode of the fuel cell to provide fuel hydrogen for the fuel cell. The fuel cell and the power supply unit are arranged in parallel to form a hybrid power supply system.

[0008] The fuel cell comprises a battery positive electrode, a battery negative electrode, a battery air channel, a battery hydrogen channel and a battery ion exchange membrane. The battery positive electrode and the battery negative electrode are separated by the battery ion exchange membrane to form two independent reaction areas. The battery air channel is arranged on the outside of the battery positive electrode and is connected to the battery positive electrode. External air enters the battery positive electrode area through the battery air channel. The battery hydrogen channel is arranged on the outside of the battery negative electrode and is connected to the battery negative electrode. Hydrogen from the pure hydrogen collector enters the battery negative electrode area through the battery hydrogen channel.

[0009] The power supply unit includes a battery and a supercapacitor arranged in parallel, the positive electrode of the battery is connected to the positive electrode of the battery and the positive electrode of the supercapacitor, and the negative electrode of the battery is connected to the negative electrode of the battery and the negative electrode of the supercapacitor to form a parallel power supply system, and through a unidirectional power-carrying element (such as a diode), the fuel cell can charge the battery and the supercapacitor, and the battery can charge the supercapacitor, and reverse charging cannot be achieved.

[0010] The system also includes a second heat exchanger and a hydrogen burner. The second heat exchanger includes a second heat exchange air channel and a second heat exchange flue gas channel. The outlet of the hydrogen burner is connected to the inlet of the ammonia decomposition reaction flue gas channel to provide heat energy for the decomposition of ammonia in the ammonia decomposition reactor. The outlet of the ammonia decomposition reaction flue gas channel is connected to the inlet of the second heat exchange flue gas channel to preheat the air entering the second heat exchange air channel. The outlet of the second heat exchange flue gas channel is connected to the flue gas treatment and release unit to treat and release the flue gas after combustion and heat exchange.

[0011] The system also includes an air compressor, and the outlet of the air compressor is divided into two paths, one of which is connected to the inlet of the second heat exchange air channel, and the other is connected to the positive electrode of the fuel cell.

[0012] The system also includes a gas mixer, and the hot air after heat exchange in the second heat exchanger and the unpurified hydrogen through the unpurified hydrogen channel enter the gas mixer; the outlet of the pure hydrogen collector is connected to the gas mixer, and the purified hydrogen in the pure hydrogen collector flows into the gas mixer as ignition hydrogen; the mixed gas flowing out after the gases are mixed in the gas mixer flows into the burner, and is ignited and burned in the burner to produce high-temperature flue gas.

[0013] Preferably, the battery comprises a lithium-ion battery or a sodium-ion battery.

[0014] The separation membrane used for purification in the membrane separation purifier is a selective hydrogen permeable membrane, which can efficiently separate hydrogen from other gases; after the gas flows out from the outlet of the product gas channel of the first heat exchanger, it enters the unpurified hydrogen channel of the purifier, and then the gas will be split into two directions, among which the hydrogen that passes through the selective hydrogen permeable membrane enters the purified hydrogen channel, and the unpurified gas that does not pass through the selective hydrogen permeable membrane, containing hydrogen, nitrogen and a small amount of unreacted ammonia, enters the gas mixer.

[0015] Preferably, the separation membrane in the membrane separation purifier is a metal vanadium or metal niobium alloy membrane, and the alloy material is represented by M1 x M2 y M3 z , wherein M1 represents one or two of metals V and Nb, M2 represents one or more of metals W, Mo, and Ta, and M1 and M2 form a solid solution, M3 is a deoxidation alloying element, representing one of Cr, Mn, Ti, Al, Y, Ma, La, Sr, Ba, and Ce, and the subscripts x, y, and z represent the molar fractions of M1, M2, and M3 element atoms, respectively, wherein x is 0.87 to 0.96, y is 0.03 to 0.13, z is 0.005 to 0.01, and x+y+z=1.00.

[0016] Preferably, the operating temperature of the separation membrane is 240-640° C., and the pressure of the gas entering the membrane separation purifier is >0.2 MPa.

[0017] More preferably, the operating temperature of the separation membrane is 300-400° C., and the pressure of the gas entering the membrane separation purifier is 0.4-1.2 MPa.

[0018] Preferably, the ammonia decomposition reactor is a fixed bed reactor, and an ammonia decomposition catalyst is filled in the ammonia channel of the ammonia decomposition reactor. The reactant ammonia gas flow flows out of the first heat exchanger and enters the ammonia channel of the ammonia decomposition reactor, flows through the ammonia decomposition catalyst, and is converted into decomposition products to obtain hydrogen and nitrogen.

[0019] Preferably, the ammonia decomposition catalyst is one of an iron-based catalyst and a ruthenium-based catalyst or a mixture of the two. After the device is running smoothly, the reaction conditions of the ammonia decomposition reactor are as follows: the operating temperature is 340-840°C, the gas pressure in the reactor is controlled at 0.2-3MPa, and the ammonia gas space velocity is 100-10000h -1 .

[0020] Preferably, the reaction conditions of the ammonia decomposition reactor are as follows: the operating temperature is 440-580°C, the gas pressure in the reactor is controlled at 0.5-1.5 MPa, and the ammonia gas space velocity is 1400-6000 h -1 .

[0021] The burner contains an ignition device. Under appropriate fuel flow rate and air flow rate, after successful ignition and stable operation of the device, the air flow rate is 4 to 30 times the ammonia flow rate flowing into the ammonia decomposition reactor; whether the fuel combustion state is normal is judged by whether the burner outlet temperature is not less than 640°C.

[0022] The purity of the purified hydrogen flowing out of the membrane separation purifier is not less than 99.99%.

[0023] The technical solution of the present invention has the following advantages:

[0024] A. The present invention realizes the stable preparation, efficient utilization and flexible energy storage of hydrogen by integrating key components such as ammonia decomposition hydrogen production, fuel cells, batteries and supercapacitors. Among them, the ammonia decomposition hydrogen production subsystem improves the yield and purity of hydrogen by optimizing the processes of ammonia gasification, heat exchange, decomposition, purification, etc. The fuel cell uses the generated hydrogen as fuel to react with air to generate electricity; the battery and supercapacitor are used as energy storage elements to balance the energy supply and demand of the system and improve the stability and reliability of the system.

[0025] B. The present invention combines fuel cells with batteries and supercapacitors into a hybrid power supply system, which not only improves the stability and reliability of power supply, but also realizes the complementary utilization of energy, ensuring stable power output under various working conditions. Through the design of unidirectional power supply elements, the charging of fuel cells to batteries and supercapacitors, and the charging of batteries to supercapacitors are realized, but reverse charging is prohibited, ensuring the safety of the charging process and the rationality of energy flow.

[0026] C. The system of the present invention combines the advantages of ammonia's high-density hydrogen content, and the advantages of batteries and supercapacitors with appropriate power storage, high power density, and instantaneous operation. The entire system has a high energy storage density, a short startup time, and high power. Capacitors, batteries, and fuel cells work in relays, and the storage energy values ​​of ammonia and electricity are optimized to ensure smooth operation of the system. Through system optimization, the hydrogen production system of the present invention can be achieved from cold start at room temperature to stable hydrogen supply within 20 minutes. Compared with the general ammonia decomposition hydrogen production system, the time is greatly shortened, thereby greatly reducing the requirements for the battery energy storage capacity.

[0027] D. In terms of temperature and pressure matching, the preferred operating temperature of the metal separation membrane of the present invention is 300-400°C, and the temperature in the reactor is preferably 440-580°C. It can be seen that the temperature and pressure range of the product gas after passing through the first heat exchanger will have a good match with the operating temperature range of the metal separation membrane, especially the preferred reaction temperature and pressure range, which is well matched with the temperature and pressure range with good separation performance of the alloy membrane. This makes it unnecessary to further heat and pressurize the product gas when the alloy membrane is used for gas separation and purification, which simplifies the process and saves overall energy consumption.

[0028] E. The present invention makes full use of the working temperature and pressure characteristics of the ammonia decomposition hydrogen production reaction, making it suitable for using non-precious metal alloy membranes for hydrogen purification. The use of non-precious metal alloy membranes greatly reduces the cost of separation membranes compared to palladium-based membranes; on the other hand, compared with the commonly used pressure swing adsorption separation method, the alloy membrane in the present invention has greatly reduced weight and volume for the same hydrogen separation flux, which is of great significance for the miniaturization, modularization, and mobility of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1This is a schematic diagram of the overall structure of the ammonia-to-hydrogen fuel cell-battery hybrid power supply system.

[0031] The following are marked in the figure:

[0032] 1-liquid ammonia source; 2-gasifier; 3-first heat exchanger, 31-first heat exchange ammonia channel, 32-first heat exchange product gas channel; 4-ammonia decomposition reactor, 41-ammonia decomposition reaction ammonia channel, 42-ammonia decomposition reaction flue gas channel; 5-second heat exchanger, 51-second heat exchange air channel, 52-second heat exchange flue gas channel; 6-membrane separation purifier, 61-unpurified hydrogen channel, 62-purified hydrogen channel; 7-fuel cell, 71-battery positive electrode, 72-battery negative electrode, 73-battery air channel, 74-battery hydrogen channel, 75-battery ion exchange membrane; 8-gas mixer; 9-hydrogen burner; 10-pure hydrogen collector; 20-air compressor; 30-flue gas treatment and release unit; 40-power supply unit, 401-battery, 402-supercapacitor, 403-current unidirectional element, 404-positive and negative electrodes at the output end of the power supply unit. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] like Figure 1As shown, this embodiment provides an ammonia-to-hydrogen fuel cell-battery hybrid power supply system, including a liquid ammonia source 1, a vaporizer 2, a first heat exchanger 3, an ammonia decomposition reactor 4, a membrane separation purifier 6, a pure hydrogen collector 10, a fuel cell 7 and a power supply unit 40; the liquid ammonia source 1 is connected to the vaporizer 2, and is used to gasify the liquid ammonia into ammonia; the first heat exchanger 3 includes a first heat exchange ammonia channel 31 and a first heat exchange product gas channel 32, the ammonia decomposition reactor 4 includes an ammonia decomposition reaction ammonia channel 41 and an ammonia decomposition reaction flue gas channel 42, the membrane separation purifier 6 includes an unpurified hydrogen channel 61 and a purified hydrogen channel 62, the outlet of the vaporizer 2 is connected to the inlet of the first heat exchange ammonia channel 31, and the outlet of the first heat exchange ammonia channel 31 is connected to the inlet of the ammonia decomposition reaction ammonia channel 41, The ammonia after heat exchange in the first heat exchanger 3 is passed into the ammonia decomposition reactor 4 for ammonia decomposition; the outlet of the ammonia channel 41 of the ammonia decomposition reaction is connected to the inlet of the first heat exchange product gas channel 32, and the outlet of the first heat exchange product gas channel 32 is connected to the inlet of the purified hydrogen channel 62. The product mixed gas after decomposition by the ammonia decomposition reactor 4 is used as the heat exchange medium of the first heat exchanger 3 and is heat exchanged with the ammonia through the first heat exchange ammonia channel 31, and then passed into the membrane separation purifier 6 for hydrogen purification; the outlet of the purified hydrogen channel 62 is connected to the inlet of the pure hydrogen collector 10, and the purified hydrogen is cooled and collected for storage. The outlet of the pure hydrogen collector 10 is connected to the negative electrode of the fuel cell 7 to provide fuel hydrogen for the fuel cell 7. The fuel cell 7 is arranged in parallel with the power supply unit 40 to form a hybrid power supply system. The present invention realizes the stable preparation, efficient utilization and flexible energy storage of hydrogen by integrating key components such as ammonia decomposition hydrogen production, fuel cell and power supply unit. Among them, the ammonia decomposition hydrogen production subsystem improves the yield and purity of hydrogen by optimizing the ammonia gasification, heat exchange, decomposition, and purification processes; the fuel cell uses the generated hydrogen as fuel to react with air to generate electricity; the power supply unit acts as an energy storage element to balance the system's energy supply and demand and improve system stability and reliability.

[0035] Furthermore, the fuel cell 7 includes a battery positive electrode 71, a battery negative electrode 72, a battery air channel 73, a battery hydrogen channel 74 and a battery ion exchange membrane 75. The battery positive electrode 71 and the battery negative electrode 72 are separated by the battery ion exchange membrane 75 to form two independent reaction areas. The battery air channel 73 is arranged on the outside of the battery positive electrode 71 and is connected to the battery positive electrode 71. External air enters the battery positive electrode 71 area through the battery air channel 73. The battery hydrogen channel 74 is arranged on the outside of the battery negative electrode 72 and is connected to the battery negative electrode 72. Hydrogen from the pure hydrogen collector 10 enters the battery negative electrode 72 area through the battery hydrogen channel 74.

[0036] The power supply unit 40 includes a battery 401 and a supercapacitor 402 arranged in parallel, the positive electrode 71 of the battery is connected to the positive electrode of the battery 401 and the positive electrode of the supercapacitor 402, and the negative electrode 72 of the battery is connected to the negative electrode of the battery 401 and the negative electrode of the supercapacitor 402, forming a parallel power supply system, and through a unidirectional power supply element 403 (such as a diode, etc.), the fuel cell 7 can charge the battery 401 and the supercapacitor 402, and the battery 401 can charge the supercapacitor 402, and the reverse charging of the above charging cannot be realized. The positive and negative electrodes 404 of the total power supply system can, in principle, be connected to any downstream power load. The present invention combines a fuel cell with a battery and a supercapacitor into a hybrid power supply system, which not only improves the stability and reliability of the power supply, but also realizes the complementary utilization of energy, ensuring that stable power output can be provided under various working conditions. The battery 401 can be selected from one of a lithium ion battery or a sodium ion battery or other, which is not specifically limited here.

[0037] The system also includes a second heat exchanger 5 and a hydrogen burner 9. The second heat exchanger 5 includes a second heat exchange air channel 51 and a second heat exchange flue gas channel 52. The outlet of the hydrogen burner 9 is connected to the inlet of the ammonia decomposition reaction flue gas channel 42 to provide heat energy for the decomposition of ammonia in the ammonia decomposition reactor 4. The outlet of the ammonia decomposition reaction flue gas channel 42 is connected to the inlet of the second heat exchange flue gas channel 52 to preheat the air entering the second heat exchange air channel 51. The outlet of the second heat exchange flue gas channel 52 is connected to the flue gas treatment and release unit 30 to treat and release the flue gas after combustion and heat exchange. The present invention realizes efficient recovery and utilization of energy by performing multi-stage heat exchange between the heat generated in the ammonia decomposition process and the heat generated in the combustion process. In particular, the high-temperature flue gas generated by combustion is used to preheat the ammonia entering the ammonia decomposition reactor, which reduces energy consumption and improves the overall thermal efficiency of the system.

[0038] The separation membrane used for purification in the membrane separation purifier 6 is a selective hydrogen permeable membrane, which can efficiently separate hydrogen from other gases. After the gas flows out from the outlet of the product gas channel 32 of the first heat exchanger 3, it enters the unpurified hydrogen channel 61 of the purifier 6, and then the gas will be split into two directions, among which the hydrogen that passes through the above separation membrane enters the purified hydrogen channel 62, and the unpurified gas that does not pass through the separation membrane, containing hydrogen, nitrogen and a small amount of unreacted ammonia, enters the gas mixer 8.

[0039] Specifically, the separation membrane of the membrane separation purifier 6 is a metal vanadium or metal niobium alloy membrane, and the alloy material can be expressed as: M1 x M2 y M3 z; Wherein M1 represents metal V or Nb, or both, M2 represents one or more of metals W, Mo, Ta, and M3 represents one of Cr, Mn, Ti, Al, Y, Ma, La, Sr, Ba, and Ce; subscripts x, y, and z represent the molar fractions of M1, M2, and M3 element atoms, respectively, where x is 0.87 to 0.96, y is 0.03 to 0.13, and z is 0.005 to 0.01, and x+y+z=1.00; M1 and M2 form a solid solution, and M3 acts as a deoxidation alloying element. In this embodiment, the separation membrane in the membrane separation purifier 6 adopts a metal vanadium-niobium alloy membrane, and the specific material can be expressed as V 0.80 Nb 0.12 Mo 0.05 Cr 0.03 The working temperature of the separation membrane is 240-640°C, preferably 300-400°C; the working pressure, i.e. the gas pressure entering the membrane separator is >0.2MPa, preferably 0.4-1.2MPa; it is worth noting that the separation process parameters outside the above working temperature and pressure do not mean that the hydrogen separation and purification is completely ineffective, but may lead to one or more situations such as reduced purification efficiency, reduced hydrogen purity, and faster damage to the separation membrane.

[0040] The ammonia decomposition reactor 4 uses a fixed bed reactor, and the ammonia decomposition catalyst is filled in the ammonia channel of the reactor. The reactant ammonia gas flow flows out from the first heat exchanger 3 and enters the ammonia channel 41 of the reactor, and flows through the ammonia decomposition catalyst to be converted into decomposition products to obtain hydrogen and nitrogen. In the ammonia decomposition reactor 4, when the device is running smoothly, the process conditions adopted are as follows: the ammonia decomposition catalyst is an iron-based catalyst, or a ruthenium-based catalyst, or a mixture of the two types of catalysts; after the device is running smoothly, the reaction conditions of the reactor are as follows: the operating temperature is 340-840°C, preferably 440-580°C; the gas pressure in the reactor is controlled at 0.2-3MPa, preferably 0.5-1.5MPa; the ammonia gas space velocity is 100-10000h -1 , preferably 1400~6000h -1 .

[0041] The purity of the purified hydrogen flowing out of the membrane separation purifier 6 is not less than 99.99%; the hydrogen yield calculated based on this portion of hydrogen can reach 60-86%.

[0042] The system further includes an air compressor 20, the outlet of the air compressor 20 is divided into two paths, one path is connected to the inlet of the second heat exchange air channel 51, and the other path is connected to the battery positive electrode 71 of the fuel cell 7. The system further includes a gas mixer 8, the hot air after heat exchange in the second heat exchanger 5 and the unpurified hydrogen through the unpurified hydrogen channel 61 enter the gas mixer 8; the outlet of the pure hydrogen collector 10 is connected to the gas mixer 8, and the purified hydrogen in the pure hydrogen collector 10 is used as ignition hydrogen to flow into the gas mixer 8; the mixed gas flowing out after the gas is mixed in the gas mixer 8 flows into the burner 9, and is ignited and burned in the burner 9 to produce high-temperature flue gas.

[0043] In terms of temperature and pressure matching, the preferred operating temperature of the metal separation membrane of the present invention is 300-400°C, and the temperature in the reactor is preferably 440-580°C. It can be seen that the temperature and pressure range of the product gas after passing through the first heat exchanger will match well with the operating temperature range of the metal separation membrane, especially the preferred reaction temperature and pressure range, which matches well with the temperature and pressure range with good separation performance of the alloy membrane. This makes it unnecessary to further heat and pressurize the product gas when the alloy membrane is used for gas separation and purification, which simplifies the process and saves overall energy consumption.

[0044] Advantages of using non-precious metal membrane separators:

[0045] An obvious common sense in this field is that the purity of hydrogen significantly affects the quality or value of the hydrogen product. For example, one of the requirements for hydrogen purity for low-temperature hydrogen-oxygen fuel cells is that the purity is not less than 99.99%. Therefore, hydrogen produced by chemical reactions usually requires a purification process to greatly increase the value of hydrogen products. Corresponding to the commonly used hydrogen purification methods, the more mature ones are mainly metal membrane separation method and pressure swing adsorption (PSA) based on pressure swing adsorption technology.

[0046] The PSA method utilizes the different adsorption capacities of porous materials such as molecular sieves for different gas molecules, as well as the different adsorption, desorption capacity, and rate change values ​​under pressure swing. Through multiple pressure swing operations, some molecules of the raw gas (usually impurity molecules) are adsorbed on the porous material while more target gas molecules are desorbed, thereby purifying the target gas. The pressure swing adsorption method is a mature technology, and the gas can be purified to a high purity according to the purity requirements. Its disadvantage is that the device is too large and too heavy, which is not suitable for factory sites, and it is difficult to apply to mobile, skid-mounted, and modular equipment.

[0047] The metal membrane separation principle uses the screening effect of the metal lattice for substances of different sizes and different chemical affinities at a certain temperature to allow the target gas molecules to pass through the metal membrane faster while the impurity molecules cannot or are slower to pass through the metal membrane. Its advantages are high separation efficiency per unit mass of equipment, strong chemical selectivity, and easy miniaturization and lightweight of the device. The main disadvantage is that there are not many types of materials to choose from and the cost is relatively high. In particular, the metal palladium membrane, which is currently the most widely used, has a high cost of use due to the precious metal properties of the material and the high processing cost.

[0048] The present invention makes full use of the working temperature and pressure characteristics of the ammonia decomposition hydrogen production reaction, making it suitable for using non-precious metal alloy membranes for hydrogen purification. The use of non-precious metal alloy membranes greatly reduces the cost of separation membranes compared to palladium-based membranes; on the other hand, compared with the commonly used pressure swing adsorption separation method, the alloy membrane in the present invention has greatly reduced weight and volume for the same hydrogen separation flux, which is of great significance for the miniaturization, modularization and mobility of the device.

[0049] The fixed bed reactor is a type of reactor commonly used by technicians in the field or chemical industry. Its main feature is that the catalyst is filled in the reactor, and the raw gas passes through the catalyst bed at a certain temperature, pressure and flow rate to form a reaction product. In this case, the ammonia gas flowing out of the first heat exchanger enters the reactor and forms product nitrogen and hydrogen after passing through the catalyst.

[0050] Due to the thermal effect of the reaction in the fixed bed reactor and the uneven heating of the heat source, the catalyst bed temperature in the reactor, usually called the reaction temperature, is often not uniform at different spatial points, usually within a temperature range. Typically, the temperature difference at different points can be in the range of 10 to 40°C.

[0051] “Gas space velocity” is a commonly used technical term in fixed bed reactor technology. It refers to the volume of gas flowing through a unit volume of catalyst per unit time under standard conditions. Its unit is usually h. -1 .

[0052] Physical quantities such as reaction conversion rate, yield, gas purity, and the measurement and calculation methods recognized in the field are used for calculation.

[0053] The fuel cell described in this application refers to a hydrogen-oxygen fuel cell, preferably a fuel cell in which the negative electrode fuel is high-purity hydrogen and the positive electrode uses air as the oxygen source. Those skilled in the art should know that the hydrogen-oxygen fuel cell has a high requirement for the purity of hydrogen, which needs to reach no less than 99.99% (v / v).

[0054] The ammonia hydrogen production system of the present invention (such as Figure 1Components 1-10) in the device can realize the time from starting from room temperature to the time when the pure hydrogen collector 10 smoothly supplies hydrogen to the fuel cell 7 in no more than 20 minutes, and the quality of the hydrogen enables the fuel cell 7 to work normally. It is worth noting that the short startup time will reduce the subsequent storage capacity requirements of the battery and supercapacitor. As long as the battery 401 and the supercapacitor 402 in the power supply unit can provide the downstream power load with a storage capacity of 20 minutes, the entire power supply system can achieve continuous and stable power supply. This storage capacity is relatively easy to achieve with the current technical level, so the specific selection of batteries and supercapacitors is not limited in the present invention.

[0055] The system of the present invention has a compact design and integrates multiple links such as liquid ammonia storage, gasification, heat exchange, ammonia decomposition to produce hydrogen, hydrogen purification, fuel cell power generation, and charging of batteries and supercapacitors, thereby realizing continuous conversion from raw materials to electrical energy and improving the integration and automation level of the system.

[0056] Any matters not described in the present invention are applicable to the prior art.

[0057] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. An ammonia-to-hydrogen fuel cell-battery hybrid power supply system, characterized in that: The invention comprises a liquid ammonia source (1), a vaporizer (2), a first heat exchanger (3), an ammonia decomposition reactor (4), a membrane separation purifier (6), a pure hydrogen collector (10), a fuel cell (7) and a power supply unit (40); the liquid ammonia source (1) is connected to the vaporizer (2) and is used to gasify the liquid ammonia into ammonia gas; the first heat exchanger (3) comprises a first heat exchange ammonia gas channel (31) and a first heat exchange product gas channel (32); the ammonia decomposition reactor (4) comprises an ammonia decomposition reaction channel (31); a first heat exchange product gas channel (32); and a second heat exchange product gas channel (32). an ammonia channel (41) and an ammonia decomposition reaction flue gas channel (42); the membrane separation purifier (6) comprises an unpurified hydrogen channel (61) and a purified hydrogen channel (62); the outlet of the gasifier (2) is connected to the inlet of the first heat exchange ammonia channel (31); the outlet of the first heat exchange ammonia channel (31) is connected to the inlet of the ammonia decomposition reaction ammonia channel (41); the ammonia after heat exchange in the first heat exchanger (3) is passed into the ammonia decomposition reactor (41); ) for ammonia decomposition; the outlet of the ammonia decomposition reaction ammonia channel (41) is connected to the inlet of the first heat exchange product gas channel (32), the outlet of the first heat exchange product gas channel (32) is connected to the inlet of the unpurified hydrogen channel (61), the product mixed gas after decomposition by the ammonia decomposition reactor (4) is used as the heat exchange medium of the first heat exchanger (3) to exchange heat with the ammonia passing through the first heat exchange ammonia channel (31), and then enters the membrane separation purifier (6) for hydrogen purification; the purified hydrogen enters the purified hydrogen channel (62), the outlet of the purified hydrogen channel (62) is connected to the inlet of the pure hydrogen collector (10), the purified hydrogen is cooled and collected and stored, the outlet of the pure hydrogen collector (10) is connected to the negative electrode of the fuel cell (7), and provides fuel hydrogen for the fuel cell (7), the fuel cell (7) and the power supply unit (40) are arranged in parallel, and together constitute a hybrid power supply system.

2. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 1 is characterized in that: The fuel cell (7) comprises a battery positive electrode (71), a battery negative electrode (72), a battery air channel (73), a battery hydrogen channel (74) and a battery ion exchange membrane (75). The battery positive electrode (71) and the battery negative electrode (72) are separated by the battery ion exchange membrane (75) to form two independent reaction areas. The battery air channel (73) is arranged outside the battery positive electrode (71) and is in conduction with the battery positive electrode (71). External air enters the battery positive electrode (71) area through the battery air channel (73). The battery hydrogen channel (74) is arranged outside the battery negative electrode (72) and is in conduction with the battery negative electrode (72). Hydrogen from the pure hydrogen collector (10) enters the battery negative electrode (72) area through the battery hydrogen channel (74).

3. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 2 is characterized in that: The power supply unit (40) comprises a storage battery (401) and a super capacitor (402) arranged in parallel, the battery positive electrode (71) is connected to the positive electrode of the storage battery (401) and the positive electrode of the super capacitor (402), and the battery negative electrode (72) is connected to the negative electrode of the storage battery (401) and the negative electrode of the super capacitor (402), so as to form a parallel power supply system, so that the fuel cell (7) can charge the storage battery (401) and the super capacitor (402), and the storage battery (401) can charge the super capacitor (402).

4. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 3 is characterized in that: The system further comprises a second heat exchanger (5) and a hydrogen burner (9), wherein the second heat exchanger (5) comprises a second heat exchange air channel (51) and a second heat exchange flue gas channel (52), wherein the outlet of the hydrogen burner (9) is connected to the inlet of the ammonia decomposition reaction flue gas channel (42) to provide heat energy for the decomposition of ammonia in the ammonia decomposition reactor (4), the outlet of the ammonia decomposition reaction flue gas channel (42) is connected to the inlet of the second heat exchange flue gas channel (52) to preheat the air entering the second heat exchange air channel (51), and the outlet of the second heat exchange flue gas channel (52) is connected to the flue gas treatment and release unit (30) to treat and release the flue gas after combustion and heat exchange.

5. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 4 is characterized in that: The system further comprises an air compressor (20), the outlet of the air compressor (20) being divided into two paths, one path being connected to the inlet of the second heat exchange air channel (51), and the other path being connected to the positive electrode (71) of the fuel cell (7).

6. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 5 is characterized in that: The system further comprises a gas mixer (8), wherein the hot air after heat exchange in the second heat exchanger (5) and the unpurified hydrogen passing through the unpurified hydrogen passage (61) enter the gas mixer (8); the outlet of the pure hydrogen collector (10) is connected to the gas mixer (8), and the purified hydrogen in the pure hydrogen collector (10) is used as ignition hydrogen and flows into the gas mixer (8); the mixed gas flowing out after mixing in the gas mixer (8) flows into the burner (9), and is ignited and burned in the burner (9) to generate high-temperature flue gas.

7. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 3 is characterized in that: The storage battery (401) is a lithium ion battery or a sodium ion battery.

8. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 6, characterized in that: The separation membrane used for purification in the membrane separation purifier (6) is a selective hydrogen permeable membrane, which can efficiently separate hydrogen from other gases; after the gas flows out from the outlet of the product gas channel (32) of the first heat exchanger (3), it enters the unpurified hydrogen channel (61) of the purifier (6), and then the gas will be divided into two directions, wherein the hydrogen that passes through the selective hydrogen permeable membrane enters the purified hydrogen channel (62), and the unpurified gas that does not pass through the selective hydrogen permeable membrane, containing hydrogen, nitrogen and a small amount of unreacted ammonia, enters the gas mixer (8).

9. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 1, characterized in that: The ammonia decomposition reactor (4) is a fixed bed reactor. An ammonia decomposition catalyst is filled in the ammonia channel of the ammonia decomposition reactor (4). The reactant ammonia gas flow flows out of the first heat exchanger (3) and enters the ammonia channel of the ammonia decomposition reactor (4), flows through the ammonia decomposition catalyst, and is converted into decomposition products to obtain hydrogen and nitrogen.

10. The ammonia-to-hydrogen fuel cell-battery hybrid power supply system according to claim 9, characterized in that: The ammonia decomposition catalyst filled in the ammonia decomposition reactor (4) is one of an iron-based catalyst and a ruthenium-based catalyst or a mixture of the two. After the device is running smoothly, the reaction conditions of the ammonia decomposition reactor (4) are as follows: the operating temperature is 340-840° C., the gas pressure in the reactor is controlled at 0.2-3 MPa, and the ammonia gas space velocity is 100-10000 h -1 .

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