Quick starting system for hydrogen production through ammonia decomposition

Abstract

The invention discloses an ammonia decomposition hydrogen production quick starting system which comprises a liquid ammonia source, a gasifier, a first heat exchanger, an ammonia decomposition reactor, a plasma ammonia decomposition hydrogen production reactor, a membrane separation purifier, a combustor and a pure hydrogen collector. The system preheats ammonia gas through a first heat exchanger, an ammonia gas channel outlet of the first heat exchanger is divided into two paths, one path is communicated with an ammonia gas channel of an ammonia decomposition reactor for ammonia decomposition, and decomposed high-temperature product mixed gas serves as a heat source of the first heat exchanger; the other path is communicated with the plasma ammonia decomposition hydrogen production reactor and is used for quickly decomposing ammonia gas and providing a hydrogen source for quickly igniting the combustor; and the combustor provides heat energy for ammonia decomposition in the ammonia decomposition reactor. According to the invention, the plasma ammonia decomposition hydrogen production reactor is introduced, and hydrogen is generated in an extremely short time by utilizing a plasma catalysis process and is used for combustion of the combustor, so that the ammonia decomposition reactor is rapidly heated, and the starting time of the whole system is remarkably shortened.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen energy, and in particular to a quick start system for producing hydrogen by decomposing ammonia. Background Art

[0002] The traditional ammonia decomposition hydrogen production system requires a high temperature environment for the decomposition reaction of ammonia, so the process from cold start to stable hydrogen supply usually takes a long time (more than 30 minutes). This process not only affects the response speed and flexibility of the system, but also increases energy consumption and production costs. In situations where emergency hydrogen supply or rapid start-up is required, the long startup time of the traditional system has become a significant bottleneck.

[0003] An important application scenario for ammonia hydrogen production systems in the future is as a mobile independent energy system. Under the condition of independent energy supply, the main reason for the slow startup time of the ammonia decomposition hydrogen production system is the time required to reach high-temperature reaction conditions. If a backup power source such as a lithium battery is used for heating, it is limited by the heating power and equipment complexity, and it is difficult to achieve short-term heating. Therefore, quickly heating the system through fuel combustion is a solution. However, under the condition of independent energy supply, how to obtain a large amount of fuel with high calorific value is another technical problem. Therefore, how to solve the problem of rapid startup of the ammonia decomposition hydrogen production system has become an important demand and research direction in this field. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a rapid start-up system for hydrogen production by decomposing an ammonia. By introducing a plasma ammonia decomposition hydrogen production reactor, the plasma catalytic process is used to generate hydrogen in a very short time, and the hydrogen is used for combustion of the burner, thereby quickly heating the ammonia decomposition reactor and significantly shortening the startup time of the entire system.

[0005] The present invention adopts the following technical solution:

[0006] A quick start system for hydrogen production by ammonia decomposition, comprising a liquid ammonia source, a vaporizer, a first heat exchanger, an ammonia decomposition reactor, a plasma ammonia decomposition hydrogen production reactor, a membrane separation purifier, a burner and a pure hydrogen collector; 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 divided into two paths, one path 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 ammonia decomposition reactor for ammonia decomposition, and the other path is connected to the inlet of the plasma ammonia decomposition hydrogen production reactor. The outlet of the ammonia channel of the ammonia decomposition reaction 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 unpurified hydrogen channel. The product mixed gas decomposed by the ammonia decomposition reactor is used as the heat exchange medium of the first heat exchanger to exchange heat with the ammonia passing through the first heat exchange ammonia channel, and then enters the membrane separation purifier for hydrogen purification; the purified hydrogen enters the purified hydrogen channel, and the outlet of the purified hydrogen channel is connected to the inlet of the pure hydrogen collector, so as to cool, collect and store the purified hydrogen; the outlet of the plasma ammonia decomposition hydrogen production reactor is connected to the burner to provide a hydrogen source for the rapid ignition of the burner; the outlet of the 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.

[0007] The system also includes a second heat exchanger and an air compressor. The second heat exchanger includes a second heat exchange air channel and a second heat exchange flue gas channel. The outlet of the 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 air compressor is connected to the inlet of the second heat exchange air channel. 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 through the air compressor. 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.

[0008] The system also includes a gas mixer. The outlet of the second heat exchange flue gas channel, the outlet of the unpurified hydrogen channel, the outlet of the pure hydrogen collector and the outlet of the plasma ammonia decomposition hydrogen production reactor are respectively connected to the inlet of the gas mixer. The hot air after heat exchange through the second heat exchanger, the unpurified hydrogen through the unpurified hydrogen channel, the pure hydrogen collected in the pure hydrogen collector, and the hydrogen decomposed by the plasma ammonia decomposition hydrogen production reactor enter the gas mixer. After the gases are mixed in the gas mixer, the mixed gas flowing out flows into the burner and is ignited and burned in the burner to generate high-temperature flue gas.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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. After the reactant ammonia gas flow flows out from the first heat exchanger, it 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. The plasma ammonia decomposition hydrogen production reactor comprises a plasma reactor ammonia channel and a plasma generator. The plasma ammonia decomposition hydrogen production reactor is a fixed bed reactor, and the ammonia decomposition catalyst is filled in the ammonia channel of the plasma reactor; the plasma generator is installed on the outer wall of the ammonia channel of the plasma reactor, and the plasma generator adopts a dielectric barrier discharge technology route; after the reactant ammonia gas flow flows out from the first heat exchanger, except for a part entering the ammonia channel of the ammonia decomposition reactor, the other part enters the plasma reactor ammonia channel of the plasma ammonia decomposition hydrogen production reactor, and the ratio of the former flow rate to the latter flow rate is in the range of 5-40 times.

[0014] Preferably, the ammonia decomposition catalyst filled in the ammonia decomposition reactor is one or a mixture of an iron-based catalyst and a ruthenium-based catalyst; 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 .

[0015] 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 .

[0016] Preferably, the ammonia decomposition catalyst filled in the ammonia channel of the plasma reactor is a supported ruthenium-based catalyst, wherein the active metal component is ruthenium, and the catalyst carrier is lanthanum oxide, cerium oxide, yttrium oxide, zirconium oxide, titanium oxide or a mixture of the above components in any proportion; in the ammonia channel of the plasma reactor, the ammonia gas space velocity is 100 to 10000 h -1 .

[0017] More preferably, in the ammonia channel of the plasma reactor, the ammonia gas space velocity is 400 to 6000 h -1 .

[0018] 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.

[0019] The purity of the purified hydrogen flowing out of the membrane separation purifier is not less than 99.99%.

[0020] The technical solution of the present invention has the following advantages:

[0021] A. The present invention introduces a plasma ammonia decomposition hydrogen production reactor and utilizes the plasma catalytic process to generate hydrogen in a very short time (within 5 minutes), and uses the hydrogen for combustion in the burner, thereby quickly heating the ammonia decomposition reactor, significantly shortening the startup time of the entire system to about 10 minutes.

[0022] B. The plasma catalytic process of the present invention is characterized by high efficiency and low temperature, which can reduce the startup energy consumption while improving the overall energy efficiency of the system. In addition, the rapid startup capability enables the system to respond more quickly to changes in hydrogen demand, improving the flexibility and reliability of the system.

[0023] C. The quick start system of the present invention integrates multiple advanced technologies such as plasma catalysis, heat exchange, membrane separation and purification, forming an efficient, energy-saving and flexible ammonia decomposition hydrogen production solution.

[0024] 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.

[0025] 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

[0026] 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.

[0027] Figure 1This is a schematic diagram of the overall structure of the quick start system for hydrogen production by decomposing ammonia.

[0028] The following are marked in the figure:

[0029] 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-plasma ammonia decomposition hydrogen production reactor, 51-plasma reactor ammonia channel, 52-plasma generator; 6-second heat exchanger, 61-second heat exchange air channel, 62-second heat exchange flue gas channel; 7-membrane separation purifier, 71-unpurified hydrogen channel, 72-purified hydrogen channel; 8-gas mixer; 9-burner; 10-pure hydrogen collector; 20-air compressor; 30-flue gas treatment and release unit. DETAILED DESCRIPTION

[0030] 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 the embodiments. 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.

[0031] like Figure 1As shown, this embodiment provides a rapid start-up system for hydrogen production by ammonia decomposition, including a liquid ammonia source 1, a vaporizer 2, a first heat exchanger 3, an ammonia decomposition reactor 4, a plasma ammonia decomposition hydrogen production reactor 5, a membrane separation purifier 7, a burner 9 and a pure hydrogen collector 10. The liquid ammonia source 1 is connected to the vaporizer 2 for gasifying 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 plasma ammonia decomposition hydrogen production reactor 5 includes a plasma reactor ammonia channel 51 and a plasma generator 52; the membrane separation purifier 7 includes an unpurified hydrogen channel 71 and a purified hydrogen channel 72. 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 divided into two paths. One path is connected to the inlet of the ammonia decomposition reaction ammonia channel 41, and the ammonia after heat exchange in the first heat exchanger 3 is passed into the ammonia decomposition reactor 4 for ammonia decomposition; the other path is connected to the inlet of the plasma reactor ammonia channel 51 of the plasma ammonia decomposition hydrogen production reactor 5, which is used for rapid decomposition of ammonia. The outlet of the ammonia decomposition reaction ammonia channel 41 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 unpurified hydrogen channel 71. The product mixed gas after decomposition in the ammonia decomposition reactor 4 is used as the heat exchange medium of the first heat exchanger 3 and heat exchanged with the ammonia through the first heat exchange ammonia channel 31, and then passed into the membrane separation purifier 7 for hydrogen purification; the purified hydrogen enters the purified hydrogen channel 72, and the outlet of the purified hydrogen channel 72 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 plasma reactor ammonia channel 51 of the plasma ammonia decomposition hydrogen production reactor 5 is connected to the burner 9 to provide a hydrogen source for the rapid ignition of the burner 9; the outlet of the 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.

[0032] Furthermore, the system further includes a second heat exchanger 6 and an air compressor 20, the second heat exchanger 6 includes a second heat exchange air channel 61 and a second heat exchange flue gas channel 62, the outlet of the burner 9 is connected to the inlet of the ammonia decomposition reaction flue gas channel 42, and provides heat energy for the decomposition of ammonia in the ammonia decomposition reactor 4. The outlet of the air compressor 20 is connected to the inlet of the second heat exchange air channel 61, and the outlet of the ammonia decomposition reaction flue gas channel 42 is connected to the inlet of the second heat exchange flue gas channel 62, which is used to preheat the air entering the second heat exchange air channel 61 through the air compressor 20; the outlet of the second heat exchange flue gas channel 62 is connected to the flue gas treatment and release unit 30, which is used to treat and release the flue gas after combustion and heat exchange.

[0033] The system further includes a gas mixer 8. The outlet of the second heat exchange flue gas channel 62, the mixed gas outlet of the unpurified hydrogen channel 71, the outlet of the pure hydrogen collector 10 and the gas outlet of the plasma ammonia decomposition hydrogen production reactor 5 are respectively connected to the inlet of the gas mixer 8. The hot air after heat exchange through the second heat exchanger 6, the unpurified hydrogen through the unpurified hydrogen channel 71, the pure hydrogen collected in the pure hydrogen collector 10, and the hydrogen decomposed by the plasma ammonia decomposition hydrogen production reactor 5 enter the gas mixer 8. After the gases are mixed in the gas mixer 8, the mixed gas flowing out flows into the burner 9, and is ignited and burned in the burner 9 to generate high-temperature flue gas.

[0034] The separation membrane used for purification in the membrane separation purifier 7 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 71 of the purifier 7, 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 72, 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.

[0035] Specifically, the separation membrane of the membrane separation purifier 7 is made of 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 7 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.

[0036] The ammonia decomposition reactor 4 uses a fixed bed reactor, and the ammonia decomposition catalyst is filled in the ammonia channel 41 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 .

[0037] The purity of the purified hydrogen flowing out of the membrane separation purifier 7 is not less than 99.99%; the hydrogen yield calculated based on this portion of hydrogen can reach 60-86%.

[0038] The plasma ammonia decomposition hydrogen production reactor 5 uses a fixed bed reactor, and the reactor ammonia channel 51 is filled with an ammonia decomposition catalyst; a plasma generator 52 is installed on the outer wall of the ammonia channel 51, which adopts the technical type of dielectric barrier discharge, and the power supply for supplying electricity to the plasma generator is generally a battery, and the specific power supply selection is not limited in this case; after the reactant ammonia gas flow flows out of the first heat exchanger 3, in addition to a part entering the ammonia channel 41 of the ammonia decomposition reactor 4, the other part enters the ammonia channel 51 of the plasma ammonia decomposition hydrogen production reactor 5, and the ratio of the former flow rate to the latter flow rate is in the range of 5-40 times; the catalyst filled in the ammonia channel 51 is a supported ruthenium-based catalyst, wherein the active metal component is ruthenium, and the catalyst carrier is lanthanum oxide, cerium oxide, yttrium oxide, zirconium oxide, titanium oxide or any mixture of the above components in any proportion; in the ammonia channel 51, the ammonia gas space velocity is 100-10000h -1 , preferably 1400~6000h -1 .

[0039] The present invention introduces a plasma ammonia decomposition hydrogen production reactor, utilizes plasma to heat materials and assists catalysis, and the catalytic process generates hydrogen in a very short time (within 5 minutes), and is used to provide the burner 8 as a heat source in the initial stage of starting the entire system. The rapid provision of hydrogen as fuel speeds up the heat supply required for the ammonia decomposition reactor to heat up, allowing it to reach stable operating conditions more quickly, and significantly shortens the startup time of the entire system to about 10 minutes (calculated from a cold start at room temperature).

[0040] When the corresponding stable process conditions are reached in the ammonia decomposition reactor 4, the ammonia gas flow in the ammonia channel 51 of the plasma ammonia decomposition hydrogen production reactor 5 can be closed, and the power supply of the plasma generator 52 can be cut off, and the entire ammonia decomposition system can still maintain stable hydrogen production and output.

[0041] 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.

[0042] Advantages of using non-precious metal membrane separators:

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] “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 .

[0050] Physical quantities such as reaction conversion rate, yield, gas purity, and the measurement and calculation methods recognized in the field are used for calculation.

[0051] 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).

[0052] In summary, the present invention solves the problems of long startup time, high energy consumption, and poor system flexibility of the traditional ammonia decomposition hydrogen production system through technological innovation, and provides new ideas and methods for the development of the field of ammonia decomposition hydrogen production.

[0053] Any matters not described in the present invention are applicable to the prior art.

[0054] 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. A quick start system for hydrogen production by decomposition of ammonia, characterized in that: The invention comprises a liquid ammonia source (1), a gasifier (2), a first heat exchanger (3), an ammonia decomposition reactor (4), a plasma ammonia decomposition hydrogen production reactor (5), a membrane separation purifier (7), a burner (9) and a pure hydrogen collector (10); the liquid ammonia source (1) is connected to the gasifier (2) and is used to gasify the liquid ammonia into ammonia; the first heat exchanger (3) comprises a first heat exchange ammonia channel (31) and a first heat exchange product gas channel (32); the ammonia decomposition reactor (4) comprises an ammonia decomposition reaction ammonia channel (41) and an ammonia decomposition product gas channel (42); The membrane separation purifier (7) comprises an unpurified hydrogen channel (71) and a purified hydrogen channel (72); 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 divided into two paths, one of which is connected to the inlet of the ammonia decomposition reaction ammonia channel (41) to pass the ammonia after heat exchange in the first heat exchanger (3) into the ammonia decomposition reactor (4) for ammonia decomposition; and the other of which is connected to the plasma ammonia decomposition hydrogen production reactor (4) 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), and the outlet of the first heat exchange product gas channel (32) is connected to the inlet of the unpurified hydrogen channel (71). 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 (7) for hydrogen purification. ; The purified hydrogen enters the purified hydrogen channel (72), and the outlet of the purified hydrogen channel (72) is connected to the inlet of the pure hydrogen collector (10), so as to cool, collect and store the purified hydrogen; the outlet of the plasma ammonia decomposition hydrogen production reactor (5) is connected to the burner (9), so as to provide a hydrogen source for the rapid ignition of the burner (9); the outlet of the burner (9) is connected to the inlet of the ammonia decomposition reaction flue gas channel (42), so as to provide heat energy for the decomposition of ammonia in the ammonia decomposition reactor (4).

2. The ammonia decomposition hydrogen production rapid start-up system according to claim 1, characterized in that: The system further comprises a second heat exchanger (6) and an air compressor (20), wherein the second heat exchanger (6) comprises a second heat exchange air channel (61) and a second heat exchange flue gas channel (62), wherein the outlet of the 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), wherein the outlet of the air compressor (20) is connected to the inlet of the second heat exchange air channel (61), wherein the outlet of the ammonia decomposition reaction flue gas channel (42) is connected to the inlet of the second heat exchange flue gas channel (62) to preheat the air entering the second heat exchange air channel (61) through the air compressor (20), and wherein the outlet of the second heat exchange flue gas channel (62) is connected to the flue gas treatment and release unit (30) to treat and release the flue gas after combustion and heat exchange.

3. The ammonia decomposition hydrogen production quick start system according to claim 2, characterized in that: The system further comprises a gas mixer (8), wherein the outlet of the second heat exchange flue gas channel (62), the mixed gas outlet of the unpurified hydrogen channel (71), the gas outlet of the pure hydrogen collector (10) and the gas outlet of the plasma ammonia decomposition hydrogen production reactor (5) are respectively connected to the inlet of the gas mixer (8), and the hot air after heat exchange in the second heat exchanger (6), the unpurified hydrogen passing through the unpurified hydrogen channel (71), the pure hydrogen collected in the pure hydrogen collector (10), and the hydrogen decomposed by the plasma ammonia decomposition hydrogen production reactor (5) enter the gas mixer (8), and 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.

4. The ammonia decomposition hydrogen production rapid start-up system according to claim 3, characterized in that: The separation membrane used for purification in the membrane separation purifier (7) 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 (71) of the purifier (7), 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 (72), 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).

5. The ammonia decomposition hydrogen production rapid start-up system according to claim 1, characterized in that: The ammonia decomposition reactor (4) is a fixed bed reactor, and an ammonia decomposition catalyst is filled in the ammonia channel of the ammonia decomposition reactor (4). After the reactant ammonia gas flow flows out of the first heat exchanger (3), it 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. The plasma ammonia decomposition hydrogen production reactor (5) comprises a plasma reactor ammonia channel (51) and a plasma generator (52). The plasma ammonia decomposition hydrogen production reactor (5) is a fixed bed reactor. The plasma reactor ammonia channel (51) is filled with an ammonia decomposition catalyst. The plasma generator (52) is installed on the outer wall of the plasma reactor ammonia channel (51). The plasma generator (52) adopts a dielectric barrier discharge technology route. After the reactant ammonia gas flow flows out of the first heat exchanger (3), a part of it enters the ammonia channel (41) of the ammonia decomposition reactor (4), and the other part enters the plasma reactor ammonia channel (51) of the plasma ammonia decomposition hydrogen production reactor (5). The ratio of the former flow rate to the latter flow rate is in the range of 5-40 times.

6. The ammonia decomposition hydrogen production rapid start-up system according to claim 5, 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 ; The ammonia decomposition catalyst filled in the ammonia channel (51) of the plasma reactor is a supported ruthenium-based catalyst, wherein the active metal component is ruthenium, and the catalyst carrier is lanthanum oxide, cerium oxide, yttrium oxide, zirconium oxide, titanium oxide or a mixture of the above components in any proportion; in the ammonia channel (51) of the plasma reactor, the ammonia gas space velocity is 100 to 10000 h -1 .

Images