Natural gas chemical looping decarburization, hydrogen production and hydrogen storage integrated system and method

Abstract

The invention provides a natural gas chemical chain decarburization, hydrogen production and hydrogen storage integrated system and method, the system comprises a fuel reactor, an oxygen carrier and natural gas are in countercurrent contact in the fuel reactor and are subjected to an oxidation-reduction reaction, the natural gas is completely oxidized to obtain a mixed gas of H2O and CO2, and the oxygen carrier is reduced into a first solid oxide. The fuel reactor is connected with a first adjustable diverter valve, the output end of the first adjustable diverter valve is connected with a hydrogen production unit and a hydrogen storage unit in parallel, and the hydrogen production unit adopts a first solid oxide and water vapor to perform an oxidation-reduction reaction to generate hydrogen, a second solid oxide and heat energy; the hydrogen storage unit stores hydrogen in the form of a first solid oxide. The input end of the air reactor is connected with the hydrogen production unit, and the output end is connected with the fuel reactor. According to the method and the system, hydrogen can be stored in the form of the first solid oxide as required, and meanwhile, the purpose of directional separation of carbon and hydrogen can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermochemical hydrogen production and storage, and in particular to a system and method integrating natural gas chemical chain decarbonization, hydrogen production and storage. Background Art

[0002] In recent years, carbon dioxide emissions related to fossil fuels have caused climate change to become increasingly serious, and hydrogen is regarded as a promising energy carrier because of its high energy density per unit mass and no CO2 emissions at the end of use. At present, the world consumes about 85 million tons of hydrogen each year, and China's hydrogen consumption accounts for about one-third of the world's total, ranking first in the world.

[0003] Among them, chemical chain hydrogen production is the most promising hydrogen production technology for industrialization. It is a new technology that produces hydrogen and captures carbon dioxide. By dividing the natural gas steam reforming reaction into three steps, hydrogen and carbon dioxide are obtained in two reactors respectively, without the need for gas separation. It has the advantages of high hydrogen production efficiency, high hydrogen purity, and zero carbon dioxide emissions, which is very consistent with the current and future development requirements of hydrogen production technology.

[0004] At present, hydrogen is mainly used in a mode of first producing hydrogen and then storing hydrogen. The raw materials are converted into hydrogen through chemical reactions, and the hydrogen is stored in the form of high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and solid hydrogen storage as needed. In this mode, the process of converting from raw materials → hydrogen → hydrogen storage medium → terminal hydrogen involves multiple process links and energy conversion processes, which makes the energy consumption and cost of hydrogen production-storage process high. Among them, solid-state hydrogen storage is to store the prepared hydrogen in solid materials. The amount of hydrogen that can be stored in the same volume is more than twice that of liquid hydrogen storage, and the storage pressure is low and the safety is good. In solid-state hydrogen storage technology, the use of metal hydrides as hydrogen storage materials is relatively mature. When hydrogen storage alloys undergo hydrogen absorption reactions in hydrogen storage tanks, heat is usually released. During the hydrogen release process, hydrogen storage alloys need to absorb heat to release hydrogen, which requires additional heat supply during the terminal release of hydrogen, increasing the complexity and energy consumption of the hydrogen storage-release system.

[0005] Therefore, as hydrogen energy is increasingly widely used, there is an urgent need for a hydrogen production and storage method with low energy loss and high safety performance. Summary of the invention

[0006] In order to solve the technical problems of high energy consumption, high cost, complex system design and the like in the existing hydrogen production and storage methods, the present invention discloses a system integrating natural gas chemical chain decarbonization, hydrogen production and storage, the system comprising a fuel reactor, a hydrogen production unit, a hydrogen storage unit and an air reactor.

[0007] The oxygen carrier is input through the upper part of the fuel reactor, countercurrently contacts with the natural gas input through the lower part of the fuel reactor and undergoes oxidation-reduction reaction at a set temperature. The natural gas is completely oxidized to obtain a mixed gas of H2O and CO2, and the oxygen carrier is reduced to a first solid oxide.

[0008] The fuel reactor is connected to a first adjustable diverter valve, and the output end of the first adjustable diverter valve is connected in parallel with the hydrogen production unit and the hydrogen storage unit. The hydrogen production unit uses the first solid oxide output by the fuel reactor to undergo an oxidation-reduction reaction with water vapor to generate hydrogen, a second solid oxide and thermal energy, and the hydrogen storage unit stores the hydrogen in the form of the first solid oxide output by the fuel reactor.

[0009] The input end of the air reactor is connected to the hydrogen production unit, and the output end is connected to the fuel reactor. The air reactor is used to oxidize the second solid oxide output from the hydrogen production unit into the oxygen carrier and generate heat energy.

[0010] In an optional embodiment, the system also includes a second adjustable diverter valve, the input end of the second adjustable diverter valve is connected to the fuel reactor, and the output end is connected in parallel with the first adjustable diverter valve and the air reactor, and the air reactor oxidizes the first solid oxide output through the second adjustable diverter valve into the oxygen carrier.

[0011] In an optional embodiment, the system further comprises a cyclone separator, wherein the cyclone separator is located between the fuel reactor and the air reactor and is used for separating the air in the oxygen carrier output from the air reactor.

[0012] In an optional embodiment, the hydrogen storage unit and the hydrogen production unit or the hydrogen release unit are detachably connected to form an integrated hydrogen storage and release unit, and the hydrogen production unit or the hydrogen release unit uses water vapor and the first solid oxide output by the hydrogen storage unit to carry out an oxidation-reduction reaction to generate hydrogen and a second solid oxide, and outputs the generated second solid oxide to the air reactor for an oxidation reaction to generate the oxygen carrier and generate heat energy.

[0013] In an optional embodiment, the hydrogen production unit and the hydrogen release unit are both connected to a steam generator, and the steam generator converts water liquid into water vapor by using the heat energy generated by the hydrogen production unit or the hydrogen release unit.

[0014] In an optional embodiment, the fuel reactor (1) is connected to a gas-liquid separator, and the gas-liquid separator is used to perform gas-liquid separation on a mixture of H2O and CO2 to obtain CO2 gas.

[0015] In an optional embodiment, the energy for setting the temperature for the redox reaction in the countercurrent reactor is provided by the heat energy generated by the air reactor.

[0016] In an optional embodiment, the oxygen carrier is any one of iron oxide, cerium oxide, and perovskite. The first solid oxide of the iron oxide (Fe2O3) is ferrous oxide (FeO), and the second solid oxide is ferroferric oxide (Fe3O4). The reactions in each reaction unit are shown in the following formula:

[0017] The reaction in the fuel reactor is: CH4+4Fe2O3=CO2+2H2O+8FeO;

[0018] The reaction in the hydrogen production unit and the hydrogen release unit is: 3FeO+H2O=Fe3O4+H2;

[0019] The reaction in the air reactor is: 4Fe3O4+O2+4N2=6Fe2O3+4N2, wherein nitrogen in the formula does not participate in the chemical reaction, indicating that the input oxygen and nitrogen indicate that the input gas is air.

[0020] Both cerium oxide and perovskite are non-stoichiometric oxygen-depleted. The first solid oxide of cerium oxide (CeO2) is CeO 3-x’ , the second solid oxide is CeO 3-y’ , where x ’ >y ’ ; The first solid oxide of the perovskite (ABO3) is ABO 3-x , the second solid oxide is ABO 3-y , where A and B are metal elements, the A position is generally a rare earth or alkaline earth element ion, and the B position is a transition element ion, where x>y.

[0021] The embodiment of the present invention further provides a method for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage, wherein the system for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage is used to produce hydrogen and store hydrogen, and the method comprises the following steps:

[0022] An oxygen carrier separated from air is input from the upper part of the fuel reactor, and desulfurized natural gas is input from the lower part of the fuel reactor. The oxygen carrier is in countercurrent contact with the natural gas and undergoes an oxidation-reduction reaction at a set temperature. The natural gas is completely oxidized to obtain a mixed gas of H2O and CO2, and the oxygen carrier is reduced to a first solid oxide.

[0023] According to the ratio coefficient of hydrogen production and hydrogen storage, the first solid oxide is input into the hydrogen production unit and the hydrogen storage unit, the hydrogen production unit uses the first solid oxide and water vapor to perform an oxidation-reduction reaction to obtain hydrogen, a second solid oxide and thermal energy, and the hydrogen storage unit uses the first solid oxide to store the hydrogen;

[0024] The second solid oxide is input into the air reactor to be oxidized into oxygen carriers and generate heat energy.

[0025] In an optional embodiment, the method further includes:

[0026] According to the energy requirement of the set temperature required for the redox reaction in the fuel reactor, the first solid oxide produced by the fuel reactor is input into the air reactor for oxidation reaction to obtain oxygen carriers and thermal energy, and the thermal energy is input into the fuel reactor.

[0027] In an optional embodiment, the method further includes: detachably connecting the hydrogen storage unit and the hydrogen release unit or the hydrogen production unit to form an integrated hydrogen storage and release unit, and inputting water vapor and the first solid oxide stored in the hydrogen storage unit into the hydrogen release unit or the hydrogen production unit for oxidation-reduction reaction to obtain hydrogen and a second solid oxide.

[0028] In an optional embodiment, the method further includes:

[0029] The heat energy generated by the hydrogen release unit and the hydrogen production unit is used to provide energy for steam generators connected thereto, respectively, to convert water liquid into water vapor.

[0030] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least: the system and method designed by the present invention for decarbonization of natural gas chemical chain, hydrogen production and storage can realize the functions of hydrogen production and storage. This system is different from the existing utilization mode of first producing hydrogen and then storing hydrogen. It completes the solid storage of hydrogen energy in the form of an intermediate in the intermediate process of the natural gas hydrogen production reaction, that is, hydrogen is stored in the form of a first solid oxide. The system and method have the following advantages:

[0031] 1. The hydrogen storage operation of the present invention eliminates the process of compressing and storing hydrogen or adsorbing it into a hydrogen storage medium in the traditional mode, reduces the energy consumption of hydrogen storage and regeneration processes, and improves the energy efficiency and technical economy of hydrogen production, storage and release.

[0032] 2. Through the second adjustable diverter valve, a portion of the first solid oxide produced by the fuel reactor can be directly input into the air reactor for combustion and heat release to provide the operating heat required by the fuel reactor or the entire system, thereby achieving system self-heating balance, while avoiding carbon dioxide emissions caused by direct combustion of methane, and improving the system economy.

[0033] 3. A mixture of CO2 and water vapor is obtained by completely oxidizing natural gas in a fuel reactor, and temperature control is used to avoid the first solid oxide from undergoing an oxidation-reduction reaction in the fuel reactor to produce hydrogen. The production of hydrogen is achieved in a hydrogen production unit and a hydrogen release unit, thereby achieving the purpose of directional separation of carbon and hydrogen, reducing the setting of a CO2 capture device, and obtaining high-purity H2 and CO2 after simple condensation and water removal. There is no need for a complex gas purification device, and the cost of producing hydrogen and carbon dioxide is reduced.

[0034] 4. Compared with traditional hydrogen storage methods, the present invention utilizes solid materials (first solid oxide) in the hydrogen production cycle to achieve the hydrogen storage function. During the hydrogen release process, it only needs to introduce common water vapor to achieve the function. In addition, the hydrogen release process releases heat to the outside and does not require complex conversion processes and energy input, effectively providing a hydrogen storage method with low energy loss and high safety performance.

[0035] 5. Based on the traditional hydrogen release unit, the present invention realizes the on-demand storage and release of hydrogen through an integrated hydrogen storage-release unit. At the same time, the solid hydrogen storage material can meet the short-distance storage and transportation needs of hydrogen, and regulate production according to changes in demand within a certain range. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 An architecture diagram of a system integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage disclosed in an embodiment of the present invention;

[0038] Figure 2 Another architecture diagram of the system integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage disclosed in an embodiment of the present invention;

[0039] Figure 3 A flow chart of a method for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage disclosed in an embodiment of the present invention;

[0040] Among them, 1. fuel reactor; 2. hydrogen production unit; 3. hydrogen storage unit; 4. air reactor; 5. first adjustable diverter valve; 6. second adjustable diverter valve; 7. cyclone separator; 8. hydrogen release unit; 9. steam generator. DETAILED DESCRIPTION

[0041] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0042] The following describes the implementation methods of the present application through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and the features of the embodiments can be combined with each other in the absence of conflict. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0043] The embodiment of the present invention provides a system integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage, see Figure 1 and Figure 2 As shown, the system includes a fuel reactor 1, a hydrogen production unit 2, a hydrogen storage unit 3 and an air reactor 4.

[0044] Among them, see Figure 1 and Figure 2 As shown, the fuel reactor 1 is a countercurrent reactor, the upper part of the countercurrent reactor is provided with an oxygen carrier inlet and a gas outlet, the lower part of the countercurrent reactor is provided with a natural gas inlet and a solid product outlet, the natural gas is input through the natural gas inlet, the oxygen carrier is input through the oxygen carrier inlet, countercurrent contact is carried out in the countercurrent reactor and oxidation-reduction reaction is carried out at a set temperature, the natural gas is completely oxidized to obtain a mixed gas of H2O and CO2 and output through the gas outlet, and the oxygen carrier is reduced to a first solid oxide and output through the solid product outlet. In the present invention, natural gas can be completely oxidized to obtain carbon dioxide in the fuel reactor 1, and by adopting a countercurrent reactor, the first solid oxide obtained can be prevented from contacting with water vapor to produce hydrogen, and directional separation of carbon and hydrogen can be achieved.

[0045] See also Figure 1 and Figure 2As shown, the solid product outlet of the fuel reactor 1 is connected to a first adjustable diverter valve 5, and the output end of the first adjustable diverter valve 5 is connected in parallel to the hydrogen production unit 2 and the hydrogen storage unit 3. The hydrogen production unit 2 uses the first solid oxide and water vapor to undergo an oxidation-reduction reaction to generate hydrogen, a second solid oxide, and thermal energy, and the hydrogen storage unit 3 stores the hydrogen in the form of the first solid oxide. By setting the first adjustable diverter valve 5, the ratio of the first solid oxide input into the hydrogen storage unit 3 and the hydrogen production unit 2 can be controlled to achieve on-demand hydrogen production and storage, see Figure 1 As shown, the proportional coefficient of hydrogen storage can be set to α, and the proportional coefficient of hydrogen production can be set to 1-β-α, where β is the proportional coefficient input to the air reactor. Without considering the energy supply demand, the total coefficient of hydrogen production and storage can be set to 1, even if β is 0. When the demand for hydrogen is large or increases, the proportion of α can be reduced to increase 1-β-α; when the demand for hydrogen decreases, the proportion of α can be increased to increase the proportion of hydrogen storage.

[0046] See also Figure 1 and Figure 2 As shown, the input end of the air reactor 4 is connected to the hydrogen production unit 2, and the output end is connected to the oxygen carrier inlet of the fuel reactor 1. The second solid oxide output by the hydrogen production unit 2 is oxidized into the oxygen carrier and generates heat energy in the air reactor 4. By connecting the air reactor 4 to the hydrogen production unit 2, the recycling of the oxygen carrier can be achieved. In this embodiment, the second solid oxide of the air reactor 4 comes from the hydrogen production unit 2.

[0047] In an optional embodiment, heat is released during the process of chemical chain decarbonization and hydrogen production through natural gas. In order to reduce product costs and energy consumption, the heat energy generated during the reaction process can be used to provide energy for the operation of the entire system. Figure 1 and Figure 2As shown, the system also includes a second adjustable diverter valve 6, the input end of the second adjustable diverter valve 6 is connected to the solid product outlet, and the output end is connected in parallel with the first adjustable diverter valve 5 and the air reactor 4, and the first solid oxide output by the fuel reactor 1 is oxidized into the oxygen carrier in the air reactor 4. In specific implementation, the proportional coefficient input to the first adjustable diverter valve 5 and the air reactor 4 through the second adjustable diverter valve 6 can be set according to the energy demand of the entire system, and the proportional coefficient input to the air reactor 4 is set to β, and the proportional coefficient input to the first adjustable diverter valve 5 is set to 1-β. When the energy demand in the system increases, β can be increased to ensure the normal operation of the system. In this embodiment, when β in the second adjustable diverter valve 6 is not zero, the second solid oxide of the air reactor 4 comes from the hydrogen production unit 2, and the first solid oxide comes from the fuel reactor 1, wherein the valence state of the first solid oxide < the valence state of the oxygen carrier < the valence state of the second solid oxide.

[0048] In an optional embodiment, in order to prevent the fuel reactor 1 from containing other gases other than carbon and affecting the purity of carbon dioxide, see Figure 1 As shown, a cyclone separator 7 is provided between the fuel reactor 1 and the air reactor 4 , and the cyclone separator 7 is used to separate the air in the oxygen carrier output from the air reactor 4 .

[0049] In an optional embodiment, the purpose of the hydrogen storage unit 3 is to store excess hydrogen according to the hydrogen demand and release it when needed. Figure 1 As shown, the system also includes a hydrogen release unit 8, the input end of the hydrogen release unit 8 is connected to the hydrogen storage unit 3 to form an integrated hydrogen storage and release unit, and the output end is connected to the air reactor 4; the hydrogen release unit 8 uses water vapor and the first solid oxide stored in the hydrogen storage unit 3 to carry out an oxidation-reduction reaction to generate hydrogen and a second solid oxide, and the hydrogen release unit 8 outputs the generated second solid oxide to the air reactor 4 for an oxidation reaction to generate the oxygen carrier and generate heat energy. In an embodiment of the present invention, when β, α, and 1-β-α are not zero, and the hydrogen release unit 8 is in operation, the second solid oxide in the air reactor 4 comes from the hydrogen production unit 2 and the hydrogen release unit 8, and the first solid oxide comes from the fuel reactor 1. See. Figure 2 As shown, the hydrogen storage unit 3 can also be connected to the hydrogen production unit 2 to form an integrated hydrogen storage and release unit, and hydrogen is produced by inputting the first solid oxide stored in the hydrogen storage unit 8 into the hydrogen production unit 2 for oxidation-reduction reaction.

[0050] In an alternative embodiment, see Figure 1As shown, the hydrogen production unit 2 and the hydrogen release unit 8 are both connected to a steam generator 9, and the steam generator 9 converts water liquid into water vapor by using the heat energy generated by the hydrogen production unit 2 or the hydrogen release unit 8.

[0051] In an optional embodiment not shown in the drawings, the system further includes a gas-liquid separator, which is connected to the gas outlet and is used for performing gas-liquid separation on the mixed gas of H2O and CO2 to obtain pure CO2 gas.

[0052] In an optional embodiment, the energy for setting the temperature of the redox reaction in the countercurrent reactor is provided by the heat energy generated by the air reactor 4. Preferably, a temperature sensor is provided in the countercurrent reactor, and the temperature sensor is used to sense the temperature in the countercurrent reactor, and the sensed temperature is input into the control system to compare it with the temperature of the redox reaction set in the countercurrent reactor, so as to adjust the proportional coefficient β of the second adjustable diverter valve 6, realize the self-heating balance of the system, and provide heat for the fuel reactor 1 (countercurrent reactor) and even the entire system circulation operation.

[0053] In an optional embodiment, the hydrogen production unit 2 and the hydrogen release unit 8 generate heat energy when producing hydrogen, the mixed gas output from the fuel reactor 1 has a temperature, and a large amount of heat is also generated in the air reactor 4. The present invention can provide an energy balance route to ensure the heat energy required for the operation of the system through the energy generated by the system itself. Specifically, the heat released by the reaction of the hydrogen production unit 2 can be used to provide heat for preheating the steam generator 9, the waste heat at the gas outlet of the fuel reactor 1 can provide heat for preheating the system fuel, the waste heat at the gas outlet of the air reactor 4 can provide heat for preheating the system air, and the reaction heat of the air reactor 4 can provide heat for the fuel reactor 1.

[0054] In an optional embodiment, the hydrogen storage unit 3 may be configured as a movable hydrogen storage unit to achieve short-distance transportation.

[0055] In an optional embodiment, the oxygen carrier is any one of iron oxide, cerium oxide, and perovskite, the first solid oxide of the iron oxide (Fe2O3) is ferrous oxide (FeO), and the second solid oxide is ferroferric oxide (Fe3O4), and the reactions in each reaction unit are respectively as shown in the following formula:

[0056] The reaction in the fuel reactor is: CH4+4Fe2O3=CO2+2H2O+8FeO;

[0057] The reaction in the hydrogen production unit and the hydrogen release unit is: 3FeO+H2O=Fe3O4+H2;

[0058] The reaction in the air reactor is: 4Fe3O4+O2+4N2=6Fe2O3+4N2, wherein nitrogen in the formula does not participate in the chemical reaction, indicating that the input oxygen and nitrogen indicate that the input gas is air.

[0059] Both cerium oxide and perovskite are non-stoichiometric oxygen-depleted. The first solid oxide of cerium oxide (CeO2) is CeO 3-x’ , the second solid oxide is CeO 3-y’ , where x ’ >y ’ The first solid oxide of the perovskite (ABO3) is ABO 3-x , the second solid oxide is ABO 3-y , where A and B are metal elements, rare earth or alkaline earth element ions are generally selected at A, and transition element ions are selected at B, where x>y.

[0060] The operation of the above system of the present invention can be understood as adjusting the opening of the first adjustable diverter valve 5 and the second adjustable diverter valve 6 according to the setting of the coefficients β and α in the first adjustable diverter valve 5 and the second adjustable diverter valve 6, and includes three working modes: ① hydrogen production-no hydrogen storage mode, ② hydrogen production-hydrogen storage mode, and ③ all hydrogen storage mode. Among them, ① hydrogen production-no hydrogen storage mode: the first solid oxide output from the solid product outlet of the fuel reactor 1 enters the hydrogen production unit 2, the hydrogen storage and release integrated unit and the air reactor 4, and the proportion of the first solid oxide entering the hydrogen production unit 2 and the hydrogen storage unit 3 of the hydrogen storage and release integrated unit is adjusted by the first adjustable diverter valve 5 to control the proportion of hydrogen storage and hydrogen production, at this time α = 0; ② hydrogen production-hydrogen storage mode: the first solid oxide output from the solid product outlet of the fuel reactor 1 flows to the hydrogen production unit 2 and the air reactor 4, and does not enter the hydrogen storage unit 3 (that is, α is set to 0), at this time 0 < α < 1-β. The solid product outlet of the fuel reactor 1 outputs a part of the first solid oxide into the air reactor 4 to release heat to provide the necessary heat for the system cycle, and the rest all enter the hydrogen production unit 2 to complete the hydrogen release; ③ All hydrogen storage mode: the solid product outlet of the fuel reactor 1 outputs the first solid oxide to flow to the hydrogen storage unit 3 (that is, 1-β-α is set to 0) and the air reactor 4, and does not enter the hydrogen production unit 2. The solid product outlet of the fuel reactor 1 outputs a part of the first solid oxide into the air reactor 4 to release heat to provide the necessary heat for the system cycle, and the rest all enter the hydrogen storage unit 3 to store hydrogen in the form of the first solid oxide, that is, at this time α=1-β.

[0061] The embodiment of the present invention also provides a method for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage, using the above natural gas chemical chain decarbonization, hydrogen production and hydrogen storage integrated system to produce hydrogen and store hydrogen, see Figure 3 As shown, the method comprises the following steps:

[0062] The oxygen carrier separated from the air is input from the upper part of the fuel reactor 1, and the desulfurized natural gas is input from the lower part of the fuel reactor 1, so that the oxygen carrier and the natural gas are in countercurrent contact and undergo oxidation-reduction reaction at a set temperature, the natural gas is completely oxidized to obtain a mixed gas of H2O and CO2 and output through the gas outlet, and the oxygen carrier is reduced to a first solid oxide;

[0063] According to the ratio coefficient of hydrogen production and hydrogen storage, the first solid oxide is input into the hydrogen production unit 2 and the hydrogen storage unit 3, the hydrogen production unit 2 uses the first solid oxide and water vapor to perform an oxidation-reduction reaction to obtain hydrogen, a second solid oxide and thermal energy, and the hydrogen storage unit 3 is used to store the hydrogen in the form of the first solid oxide;

[0064] The second solid oxide is input into the air reactor 4 to be oxidized into oxygen carriers and generate heat energy.

[0065] In an optional embodiment, the method further includes:

[0066] According to the energy requirement of the set temperature required for the redox reaction in the fuel reactor 1, the first solid oxide produced by the fuel reactor 1 is input into the air reactor 4 for oxidation reaction to obtain oxygen carriers and thermal energy, and the thermal energy is input into the fuel reactor 1.

[0067] In an optional embodiment, the method further includes: detachably connecting the hydrogen storage unit 3 and the hydrogen release unit 8 or the hydrogen production unit 2 to form an integrated hydrogen storage and release unit, and inputting water vapor and the first solid oxide stored in the hydrogen storage unit 3 into the hydrogen release unit 8 or the hydrogen production unit 2 for oxidation-reduction reaction to obtain hydrogen and a second solid oxide.

[0068] In an optional embodiment, the method further includes:

[0069] The heat energy generated by the hydrogen release unit 8 and the hydrogen production unit 2 is used to provide energy for the steam generator 9 connected thereto, respectively, to convert the water liquid into water vapor.

[0070] The present invention takes Fe2O3 as an oxygen carrier as an example, and describes the reaction processes of the fuel reactor 1, the hydrogen production unit 2, the hydrogen storage unit 3, and the air reactor 4 in the present invention respectively:

[0071] 1. In the fuel reactor 1, CH4 and oxygen carrier Fe2O3 are in countercurrent contact to undergo redox reaction, which is an endothermic reaction. The oxygen carrier is reduced to FeO, and CH4 is completely oxidized to obtain gaseous products including H2O and CO2. After the mixed gas is output and condensed, carbon dioxide is captured; wherein, the reaction process is: CH4+4Fe2O3=CO2+2H2O+8FeO.

[0072] 2. In the hydrogen production unit 2, FeO and water vapor undergo a redox reaction, which is an exothermic reaction. The gas outlet is a mixed gas of H2 and water vapor, and a pure hydrogen flow can be obtained through condensation. The solid product is Fe3O4, which enters the air reactor; wherein, the reaction process is: 3FeO+H2O=Fe3O4+H2.

[0073] 3. In the integrated hydrogen storage and release unit, hydrogen is stored in the form of FeO, which can be flexibly transported over short distances to meet the flexible release of hydrogen within a certain time or distance; the release process of hydrogen is completed by injecting water vapor into the hydrogen release unit 8, and the heat released during the hydrogen release process meets the heat demand of the steam generator 9, and no additional heat is required for the hydrogen release process. After the hydrogen release is completed, the solid product is Fe3O4, which is transported back to the air reactor 4.

[0074] 4. The first solid oxide (FeO) of the air reactor 4 is oxidized and restored to the oxygen carrier Fe2O3, and re-enters the fuel reactor 1 to realize the cycle. This process is an exothermic reaction. The solids input into the air reactor 4 include FeO in the fuel reactor 1, Fe3O4 in the hydrogen production unit 2, and Fe3O4 in the hydrogen release unit 8. The larger the coefficient β of the second adjustable diverter valve 6, the more heat is released in the air reactor 4, which can provide heat for the fuel reactor 1 and fuel preheating. The reaction process of converting Fe3O4 in the hydrogen production unit 2 and the hydrogen release unit 8 into the oxygen carrier Fe2O3 is: 4Fe3O4+O2+4N2=6Fe2O3+4N2, in which nitrogen does not participate in the chemical reaction in the formula, indicating that the input oxygen and nitrogen indicate that the input gas is air.

[0075] According to the actual demand for hydrogen in production and the energy requirements of system operation, the integrated method for self-thermal chemical chain hydrogen production and storage with directional separation of hydrocarbons of the present invention has the following three operating modes, and the three schemes can be flexibly switched by adjusting the diversion coefficients (i.e., proportional coefficients α, β) of the first adjustable diverter valve 5 and the second adjustable diverter valve 6.

[0076] Hydrogen production and storage mode: In this mode, the larger the β, the smaller the total amount of hydrogen production and storage, and the more heat energy generated; on this basis, when α is increased, the amount of hydrogen storage increases and the amount of hydrogen production decreases. Before the stored hydrogen is released, in order to meet the material balance, the solid inlet of the fuel reactor 1 needs to provide additional Fe2O3 from the outside. After the hydrogen storage unit 3 completes the hydrogen release, the Fe3O4 is transported back to the air reactor 4 to complete the oxidation and realize the cycle.

[0077] Mode of only producing hydrogen but not storing hydrogen: In this mode, α is set to 0, β is not 0, the first solid oxide FeO enters the air reactor 4 and the hydrogen production unit 2 respectively, and no longer enters the hydrogen storage unit 3. The FeO entering the hydrogen production unit 2 directly reacts with water vapor to produce hydrogen, and the solid product Fe3O4 is returned to the air reactor 4 to be oxidized into Fe2O3. The solid oxide completes the cycle and continuously produces hydrogen flow.

[0078] Hydrogen storage mode without hydrogen production: In this mode, 1-β-α is zero, and β is not zero. The FeO at the outlet of the fuel reactor 1 enters the corresponding air reactor 4 and hydrogen storage unit 3 through the first adjustable diverter valve 5 and the second adjustable diverter valve 6 respectively, and no longer enters the hydrogen production unit 2. The hydrogen is stored in the hydrogen storage unit 3 in the form of FeO. Before the hydrogen is released, the oxygen carrier Fe2O3 at the inlet of the fuel reactor 1 needs to be continuously supplied from the outside.

[0079] The system and method designed by the present invention for decarbonization of natural gas chemical chain, hydrogen production and storage can realize the functions of hydrogen production and storage. This system is different from the existing utilization mode of first producing hydrogen and then storing hydrogen. It completes the solid storage of hydrogen energy in the form of an intermediate in the intermediate process of the natural gas hydrogen production reaction, that is, hydrogen is stored in the form of a first solid oxide. The system and method have the following advantages:

[0080] 1. The hydrogen storage operation of the present invention eliminates the process of compressing and storing hydrogen or adsorbing it into a hydrogen storage medium in the traditional mode, reduces the energy consumption of hydrogen storage and regeneration processes, and improves the energy efficiency and technical economy of hydrogen production, storage and release.

[0081] 2. Through the second adjustable diverter valve, a portion of the first solid oxide produced by the fuel reactor can be directly input into the air reactor for combustion and heat release to provide the operating heat required by the fuel reactor or the entire system, thereby achieving system self-heating balance and improving system economy.

[0082] 3. A mixture of CO2 and water vapor is obtained by completely oxidizing natural gas in a fuel reactor, and temperature control is used to avoid the first solid oxide from undergoing an oxidation-reduction reaction in the fuel reactor to produce hydrogen. The production of hydrogen is achieved in a hydrogen production unit and a hydrogen release unit, thereby achieving the purpose of directional separation of carbon and hydrogen, reducing the setting of a CO2 capture device, and obtaining high-purity H2 and CO2 after simple condensation and water removal. There is no need for a complex gas purification device, and the cost of producing hydrogen and carbon dioxide is reduced.

[0083] 4. Compared with traditional hydrogen storage methods, the present invention utilizes solid materials (first solid oxide) in the hydrogen production cycle to achieve the hydrogen storage function. During the hydrogen release process, it only needs to introduce common water vapor to achieve the function. In addition, the hydrogen release process releases heat to the outside and does not require complex conversion processes and energy input, effectively providing a hydrogen storage method with low energy loss and high safety performance.

[0084] 5. Based on the traditional hydrogen release unit, the present invention realizes the on-demand storage and release of hydrogen through an integrated hydrogen storage-release unit. At the same time, the solid hydrogen storage material can meet the short-distance storage and transportation needs of hydrogen, and regulate production according to changes in demand within a certain range.

[0085] Obviously, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage, characterized in that: The system comprises a fuel reactor (1), a hydrogen production unit (2), a hydrogen storage unit (3) and an air reactor (4); an oxygen carrier is input through the upper part of the fuel reactor (1), countercurrently contacts with the natural gas input through the lower part of the fuel reactor (1) and undergoes an oxidation-reduction reaction at a set temperature; the natural gas is completely oxidized to obtain a mixed gas of H2O and CO2, and the oxygen carrier is reduced to a first solid oxide; The fuel reactor (1) is connected to a first adjustable diverter valve (5); the output end of the first adjustable diverter valve (5) is connected in parallel to the hydrogen production unit (2) and the hydrogen storage unit (3); the hydrogen production unit (2) uses the first solid oxide output by the fuel reactor (1) to carry out an oxidation-reduction reaction with water vapor to generate hydrogen, a second solid oxide and thermal energy; and the hydrogen storage unit (3) stores the hydrogen in the form of the first solid oxide output by the fuel reactor (1); The input end of the air reactor (4) is connected to the hydrogen production unit (2), and the output end is connected to the fuel reactor (1). The air reactor (4) is used to oxidize the second solid oxide output by the hydrogen production unit (2) into the oxygen carrier and generate heat energy.

2. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The system also includes a second adjustable diverter valve (6), the input end of the second adjustable diverter valve (6) is connected to the fuel reactor (1), and the output end is connected in parallel with the first adjustable diverter valve (5) and the air reactor (4), and the air reactor (4) oxidizes the first solid oxide output through the second adjustable diverter valve (6) into the oxygen carrier.

3. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The system further comprises a cyclone separator (7), which is located between the fuel reactor (1) and the air reactor (4) and is used to separate the air in the oxygen carrier output from the air reactor (4).

4. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The hydrogen storage unit (3) is detachably connected to the hydrogen production unit (2) or the hydrogen release unit (8) to form an integrated hydrogen storage and release unit. The hydrogen production unit (2) or the hydrogen release unit (8) uses water vapor and the first solid oxide output by the hydrogen storage unit (3) to carry out an oxidation-reduction reaction to generate hydrogen and a second solid oxide, and outputs the generated second solid oxide to the air reactor (4) for an oxidation reaction to generate the oxygen carrier and generate heat energy.

5. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage as one of claim 4, characterized in that: The hydrogen production unit (2) and the hydrogen release unit (8) are both connected to a steam generator (9), and the steam generator (9) converts water liquid into water vapor using the heat energy generated by the hydrogen production unit (2) or the hydrogen release unit (8).

6. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The fuel reactor (1) is connected to a gas-liquid separator, which is used to perform gas-liquid separation on a mixed gas of H2O and CO2 to obtain CO2 gas.

7. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The energy for setting the temperature for the redox reaction in the countercurrent reactor is provided by the heat energy generated by the air reactor (4).

8. The system for natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 1 is characterized in that: The oxygen carrier is any one of iron oxide, cerium oxide, and perovskite; When the oxygen carrier is iron oxide, the first solid oxide is ferrous oxide, and the second solid oxide is ferrosoferric oxide; When the oxygen carrier is cerium oxide, the first solid oxide is CeO 3-x’ , the second solid oxide is CeO 3-y’ , where x ’ >y ’ ; When the oxygen carrier is perovskite, the first solid oxide is ABO 3-x , the second solid oxide is ABO 3-y , A and B are both metal elements, x>y.

9. A method for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage, characterized in that: A system for natural gas chemical chain decarbonization, hydrogen production and storage as one of claims 1 to 8 is used to produce and store hydrogen, the method comprising: An oxygen carrier separated from air is input from the upper part of the fuel reactor (1), and desulfurized natural gas is input from the lower part of the fuel reactor (1), the oxygen carrier is in countercurrent contact with the natural gas and undergoes an oxidation-reduction reaction at a set temperature, the natural gas is completely oxidized to obtain a mixed gas of H2O and CO2, and the oxygen carrier is reduced to a first solid oxide; According to the ratio coefficient of hydrogen production and hydrogen storage, the first solid oxide is input into the hydrogen production unit (2) and the hydrogen storage unit (3), the hydrogen production unit (2) uses the first solid oxide and water vapor to carry out an oxidation-reduction reaction to obtain hydrogen, a second solid oxide and thermal energy, and the hydrogen storage unit (3) is used to store the hydrogen in the form of the first solid oxide; The second solid oxide is introduced into the air reactor (4) to be oxidized into oxygen carriers and generate heat energy.

10. The method for integrating natural gas chemical chain decarbonization, hydrogen production and hydrogen storage according to claim 9, characterized in that: The method further comprises: According to the energy requirement of the set temperature required for the redox reaction in the fuel reactor (1), the first solid oxide produced by the fuel reactor (1) is input into the air reactor (4) for oxidation reaction to obtain oxygen carriers and heat energy, and the heat energy is input into the fuel reactor (1); The hydrogen storage unit (3) and the hydrogen release unit (8) or the hydrogen production unit (2) are detachably connected to form an integrated hydrogen storage and release unit, and water vapor and the first solid oxide stored in the hydrogen storage unit (3) are input into the hydrogen release unit (8) or the hydrogen production unit (2) to undergo an oxidation-reduction reaction to obtain hydrogen and a second solid oxide.

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