Low-temperature thermochemical cycle water decomposition hydrogen production device and hydrogen production method

Abstract

The invention provides a low-temperature thermochemical cycle water decomposition hydrogen production device and a hydrogen production method. According to the low-temperature thermochemical cycle water decomposition hydrogen production device disclosed by the invention, the flue gas inlet is arranged for introducing high-temperature flue gas generated by biomass pyrolysis and enabling the high-temperature flue gas to directly face the heat exchange tube, so that efficient heat transfer is realized; meanwhile, a reaction gas inlet pipe is arranged at the bottom of the device and is directly connected with a heat exchange pipe, high-temperature flue gas exchanges heat with water vapor, the reaction temperature is effectively controlled within 800 DEG C, and therefore the defects that a traditional chemical circulation hydrogen production device is high in energy consumption, unstable in operation, high in maintenance cost and the like are overcome; according to the method for producing hydrogen by decomposing water through low-temperature thermochemical circulation, high-temperature flue gas which is low in price and easy to obtain is adopted as a heat source, so that unnecessary energy expenditure is saved; a gas path of high-temperature flue gas is changed through the first baffle plate and the second baffle plate, so that a heat source is utilized to the maximum extent; and the oxygen carrier is used, so that the temperature in the process of hydrogen production by thermochemical cycle decomposition of water is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production, and in particular relates to a low-temperature thermochemical cycle water decomposition hydrogen production device and a hydrogen production method. Background Art

[0002] Accelerating the development of the hydrogen energy industry is a key path to help my country achieve its goals. However, my country's current H2 production is still dominated by coal-to-hydrogen, with gray hydrogen accounting for as much as 80%. Looking to the future, the proportion of green hydrogen will increase year by year, and it is expected to reach 70% by 2050. In recent years, the thermochemical cycle water decomposition hydrogen production technology has attracted widespread attention due to its efficient green hydrogen production capacity and relatively low reaction temperature. However, the thermodynamic properties of water are relatively stable, so the thermochemical cycle water decomposition hydrogen production needs to be carried out at 1500°C. At this temperature, the conventional thermochemical cycle water decomposition hydrogen production device not only has high energy consumption and high maintenance costs, but also has poor device stability.

[0003] At present, there are few reports on devices designed for fuel-assisted thermochemical cycle water splitting to produce hydrogen and they are immature. Therefore, developing a new type of fuel-assisted thermochemical cycle water splitting to produce hydrogen is of great significance to reduce costs and energy consumption. Summary of the invention

[0004] In view of the above technical difficulties, the present invention proposes a low-temperature thermochemical cycle water decomposition hydrogen production device and hydrogen production method. The device is provided with a flue gas inlet for introducing high-temperature flue gas (1000°C) generated by biomass pyrolysis, and making it directly opposite to the heat exchange tube to achieve efficient heat transfer; at the same time, a reaction gas inlet pipe is provided at the bottom of the device, which is directly connected to the heat exchange tube and introduces water vapor with a temperature of 650°C. In order to further optimize the heat exchange effect, a first baffle is also provided in the device to enhance the heat exchange efficiency of high-temperature flue gas and water vapor. The device effectively controls the reaction temperature within 800°C, thereby overcoming the disadvantages of traditional chemical cycle hydrogen production devices such as high energy consumption, unstable operation, and high maintenance cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a low-temperature thermochemical cycle water decomposition hydrogen production device, comprising:

[0007] The outer barrel is hollow inside and has a smoke inlet at one end and a smoke outlet at the other end;

[0008] An inner barrel, which is located inside the outer barrel, and a porous sieve plate is provided inside the inner barrel for carrying oxygen carriers;

[0009] A plurality of heat exchange tubes are arranged in the outer barrel at locations corresponding to the smoke inlet, and one end of the heat exchange tube extends toward the end of the inner barrel close to the smoke inlet and is connected to the inner barrel;

[0010] The reaction gas inlet pipe is located in the outer barrel, the end of the reaction gas inlet pipe close to the heat exchange pipe is connected to the heat exchange pipe, and the end away from the heat exchange pipe extends toward the end of the outer barrel close to the flue gas inlet and passes through the outer barrel.

[0011] Preferably, the end of the inner barrel away from the heat exchange tube extends toward the end of the outer barrel close to the flue gas outlet and passes through the outer barrel, and a reaction gas outlet pipe is provided at the end of the inner barrel located outside the outer barrel.

[0012] Preferably, a plurality of first baffles are provided in the outer barrel at locations corresponding to the heat exchange tubes, and two adjacent first baffles are arranged alternately. After the heat exchange tubes pass through the plurality of first baffles, both ends are connected to the reaction gas inlet pipe and the inner barrel respectively.

[0013] Preferably, an oxygen carrier feeding pipe is provided at a position of the inner barrel corresponding to the porous sieve plate, and the oxygen carrier feeding pipe passes through the outside of the outer barrel.

[0014] Preferably, a second baffle is provided in the outer barrel at a position corresponding to the inner barrel, two adjacent second baffles are arranged alternately, and the inner barrel passes through a plurality of the second baffles in sequence.

[0015] Preferably, a heat-insulating plug is provided at the end of the inner barrel close to the reaction gas outlet pipe;

[0016] The inner barrel is provided with a temperature sensor for monitoring the temperature of the oxygen carrier;

[0017] The outer periphery of the outer barrel is also provided with ear seats and expansion joints.

[0018] In a second aspect, the present invention further provides a method for producing hydrogen by decomposing water through a low-temperature thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, comprising the following steps:

[0019] S1. placing an oxygen carrier on a porous sieve plate;

[0020] S2, passing high-temperature flue gas into the outer barrel from the flue gas inlet, so that the temperature inside the inner barrel is 750-800°C;

[0021] S3, passing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, the oxygen carrier is reduced, and CH4 is converted into synthesis gas;

[0022] S4. After the synthesis gas and unreacted CH4 and N2 in the inner barrel are removed, high-temperature flue gas is used again to make the temperature in the inner barrel reach 750-800°C, and then water vapor is introduced into the inner barrel through the reaction gas inlet pipe. The water vapor reacts with the reduced oxygen carrier to produce H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration.

[0023] Preferably, the oxygen carrier comprises at least one of nickel-doped brownmillerite, composite metal oxide, and high entropy spinel oxide;

[0024] In the step of introducing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, the flow rate of CH4 is 500-550 mL·min -1 , the flow rate of N2 is 500~550mL·min -1 ;

[0025] In the step of introducing water vapor into the inner barrel from the reaction gas inlet pipe, the flow rate of water vapor is 200-250 mL min -1 , the temperature of water vapor is 600-650℃.

[0026] Preferably, high-temperature flue gas is introduced into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 750-800°C, the introduction of high-temperature flue gas is stopped, and N2 is introduced into the outer barrel from the flue gas inlet to remove the air in the outer barrel, and then the synthesis gas reaction is carried out; wherein the flow rate of N2 is 500-100 mL·min -1 ;

[0027] The synthesis gas and unreacted CH4 and N2 in the inner barrel are removed by introducing N2 into the reaction gas inlet pipe, wherein the flow rate of N2 is 500-100 mL min -1 .

[0028] Preferably, the nickel-doped calcium iron ore is Ca2Ni 0.75 Fe 1.25 O5;

[0029] The composite metal oxide includes NiFe2O4, SrFe 12 O 19 At least one of;

[0030] The high entropy spinel oxide comprises (Ni 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )Fe2O4、(Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 ) at least one of Fe2O4;

[0031] Repeat the cycle steps S3 to S4 to achieve the cyclic preparation of H2.

[0032] The low-temperature thermochemical cycle water decomposition hydrogen production device of the present invention has the following advantages compared with the prior art:

[0033] Beneficial effects:

[0034] 1. The low-temperature thermochemical cycle water decomposition hydrogen production device of the present invention is provided with a flue gas inlet for introducing high-temperature flue gas (1000°C) generated by biomass pyrolysis, and making it directly opposite to the heat exchange tube to achieve efficient heat transfer; at the same time, a reaction gas inlet pipe is provided at the bottom of the device, which is directly connected to the heat exchange tube, and water vapor with a temperature of 650°C is introduced. The high-temperature flue gas and water vapor exchange heat, and the reaction temperature is effectively controlled within 800°C, thereby overcoming the disadvantages of high energy consumption, unstable operation, and high maintenance cost of traditional chemical cycle hydrogen production devices;

[0035] 2. In the low-temperature thermochemical cycle water decomposition hydrogen production device of the present invention, a plurality of first baffles are arranged at the corresponding heat exchange tubes in the outer barrel, and two adjacent first baffles are arranged in a staggered manner; the staggered arrangement of the first baffles enables the high-temperature flue gas to flow in an "S" shape in the outer barrel, and the high-temperature flue gas heats the water vapor in the heat exchange tube, greatly increasing the heat exchange efficiency between the flue gas and the water vapor;

[0036] 3. The low-temperature thermochemical cycle water decomposition hydrogen production method of the present invention adopts cheap and easily available high-temperature flue gas as a heat source, saving unnecessary energy expenses; the gas path of the high-temperature flue gas is changed through the first / second baffle to maximize the use of the heat source; the use of oxygen carriers reduces the temperature in the thermochemical cycle water decomposition hydrogen production process, and the use of additional baffles further reduces the reaction temperature, reduces the maintenance cost of the device and the energy consumption during operation, and improves the stability of the device; the output of green hydrogen can be achieved during the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only 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.

[0038] Figure 1 This is a schematic structural diagram of a low-temperature thermochemical cycle water decomposition hydrogen production device in one embodiment of the present invention;

[0039] Figure 2 This is a top view of a low-temperature thermochemical cycle water decomposition hydrogen production device in one embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. 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.

[0041] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0042] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0043] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0044] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0045] The present invention provides a low-temperature thermochemical cycle water decomposition hydrogen production device, such as Figures 1-2 As shown, including:

[0046] The outer barrel 1 is hollow inside, and a smoke inlet 11 is provided at one end of the outer barrel, and a smoke outlet 12 is provided at the other end;

[0047] The inner barrel 2 is located inside the outer barrel 1, and a porous sieve plate 21 is provided inside the inner barrel 2 for carrying an oxygen carrier 26;

[0048] A plurality of heat exchange tubes 3 are arranged in the outer barrel 1 at positions corresponding to the smoke inlet 11, and one end of the heat exchange tube 3 extends toward the end of the inner barrel 2 close to the smoke inlet 11 and is connected to the inner barrel 2;

[0049] The reaction gas inlet pipe 4 is located in the outer barrel 1 . The end of the reaction gas inlet pipe 4 close to the heat exchange pipe 3 is connected to the heat exchange pipe 3 , and the end away from the heat exchange pipe extends toward the end of the outer barrel 1 close to the flue gas inlet 11 and passes through the outer barrel 1 .

[0050] The low-temperature thermochemical cycle water decomposition hydrogen production device of the present invention comprises an outer barrel 1, an inner barrel 2, a plurality of heat exchange tubes 3, and a reaction gas inlet pipe 4; the outer barrel 1 and the inner barrel 2 are both cylindrical hollow barrel structures; the outer barrel 1 is provided with a flue gas outlet 12 at the upper end and a flue gas inlet 11 at the lower end, and the high-temperature flue gas enters the outer barrel 1 from the flue gas inlet 11 and exits from the flue gas outlet 12; the inner barrel 2 is sleeved inside the outer barrel 1, and a porous sieve plate 21 is provided inside the inner barrel 2, and an oxygen carrier 26 is placed on the porous sieve plate 2; a plurality of heat exchange tubes 3 are provided in the outer barrel 1 corresponding to the flue gas inlet 11, and the upper ends of the heat exchange tubes 3 are connected to the bottom of the inner barrel 2, and the lower ends are connected to the reaction gas inlet pipe 4, and the lower end of the reaction gas inlet pipe 4 extends downward and passes through the outer barrel 1.

[0051] The low-temperature thermochemical cycle water decomposition hydrogen production device of the present invention is provided with a flue gas inlet for introducing high-temperature flue gas (1000°C) generated by biomass pyrolysis, and directing it to face the heat exchange tube to achieve efficient heat transfer; at the same time, a reaction gas inlet pipe is provided at the bottom of the device, which is directly connected to the heat exchange tube, and water vapor with a temperature of 650°C is introduced. The high-temperature flue gas exchanges heat with the water vapor, and the reaction temperature is effectively controlled within 800°C, thereby overcoming the disadvantages of traditional chemical cycle hydrogen production devices such as high energy consumption, unstable operation, and high maintenance cost.

[0052] In some embodiments, the end of the inner barrel 2 away from the heat exchange tube extends toward the end of the outer barrel 1 close to the flue gas outlet 12 and passes through the outer barrel 1, and a reaction gas outlet pipe 22 is provided at the end of the inner barrel 2 located outside the outer barrel 1. Specifically, by passing a mixed gas of CH4 and N2 into the inner barrel through the reaction gas inlet pipe 4, the oxygen carrier is reduced, CH4 is converted into synthesis gas, and the synthesis gas is discharged through the reaction gas outlet pipe 22; or, water vapor is passed into the inner barrel 2 through the reaction gas inlet pipe 4, and the water vapor reacts with the reduced oxygen carrier to generate H2, which is discharged through the reaction gas outlet pipe 22.

[0053] In some embodiments, a plurality of first baffles 5 are provided in the outer barrel 1 at locations corresponding to the heat exchange tubes 3, and two adjacent first baffles 5 are arranged in a staggered manner. After the heat exchange tubes 3 pass through the plurality of first baffles 5, the two ends are respectively connected to the reaction gas inlet pipe 4 and the inner barrel 2. The first baffles 5 are arranged in a staggered manner in the outer barrel 1, and the heat exchange tubes 3 pass through the plurality of first baffles 5 in sequence. The staggered arrangement of the first baffles 5 enables the high-temperature flue gas to flow in an "S" shape in the outer barrel 1, and the high-temperature flue gas heats the water vapor in the heat exchange tubes 3, greatly increasing the heat exchange efficiency between the flue gas and the water vapor.

[0054] In some embodiments, an oxygen carrier feeding pipe 23 is provided at the inner barrel 2 corresponding to the porous sieve plate 21, and the oxygen carrier feeding pipe 23 passes through the outer barrel 1. The oxygen carrier feeding pipe 23 can be added to the porous sieve plate 21 of the inner barrel 2.

[0055] In some embodiments, a second baffle 6 is provided in the outer barrel 1 at a position corresponding to the inner barrel 1, two adjacent second baffles 6 are arranged alternately, and the inner barrel 1 sequentially passes through the plurality of second baffles 6. The second baffles 6 are arranged alternately in the outer barrel 1, and the high-temperature flue gas flows in an "S" shape in the outer barrel 1, thereby increasing the heat exchange efficiency between the high-temperature flue gas and the inner barrel 1.

[0056] In some embodiments, a heat insulating plug 24 is provided at the end of the inner barrel 2 close to the reaction gas outlet pipe 22 .

[0057] In some embodiments, a temperature sensor 25 is provided on the inner barrel 2 to monitor the temperature of the oxygen carrier; specifically, the temperature sensor 25 passes through the insulation plug 24 and extends into the inner barrel 2 to monitor the temperature inside the inner barrel 2.

[0058] In some embodiments, the outer circumference of the outer barrel 1 is further provided with an ear seat 13 and an expansion joint 14. Specifically, the ear seat 13 is arranged in the middle of the outer circumference of the outer barrel, and the expansion joint 14 is located above the ear seat 13. The outer barrel 1 and the expansion joint 14 are both made of S31008 stainless steel.

[0059] Based on the same inventive concept, the present invention also provides a method for producing hydrogen by decomposing water through a low-temperature thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, comprising the following steps:

[0060] S1. placing an oxygen carrier on a porous sieve plate;

[0061] S2, passing high-temperature flue gas into the outer barrel from the flue gas inlet, so that the temperature inside the inner barrel is 750-800°C;

[0062] S3, introducing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas (including a mixed gas of carbon monoxide and H2);

[0063] S4. After the synthesis gas and unreacted CH4 and N2 in the inner barrel are removed, high-temperature flue gas is used again to make the temperature in the inner barrel reach 750-800°C, and then water vapor is introduced into the inner barrel through the reaction gas inlet pipe. The water vapor reacts with the reduced oxygen carrier to produce H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration.

[0064] In some embodiments, the high-temperature flue gas mainly includes CO and CO2, and also includes a small amount of CH4, H2, NO, N2, H2S and other gases.

[0065] In some embodiments, the oxygen carrier comprises at least one of nickel-doped brownmillerite, a composite metal oxide, and a high entropy spinel oxide;

[0066] In the step of introducing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, the flow rate of CH4 is 500-550 mL·min -1 , the flow rate of N2 is 500~550mL·min -1 ;

[0067] In the step of introducing water vapor into the inner barrel from the reaction gas inlet pipe, the flow rate of water vapor is 200-250 mL min -1 , the temperature of water vapor is 600-650℃.

[0068] In some embodiments, high-temperature flue gas is introduced into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 750-800°C, the introduction of high-temperature flue gas is stopped, and N2 is introduced into the outer barrel from the flue gas inlet to remove the air in the outer barrel, and then the synthesis gas reaction is carried out; wherein the flow rate of N2 is 500-100 mL·min -1 ;

[0069] The synthesis gas and unreacted CH4 and N2 in the inner barrel are removed by introducing N2 into the reaction gas inlet pipe, wherein the flow rate of N2 is 500-100 mL min -1 .

[0070] In some embodiments, nickel-doped calcium iron ore is Ca2Ni 0.75 Fe 1.25 O5;

[0071] Composite metal oxides refer to two or more metal oxides, including but not limited to NiFe2O4, SrFe 12 O 19 At least one of;

[0072] High entropy spinel oxides include (Ni 0.2 Co 0.2 Ca 0.2Cu 0.2 Mg 0.2 )Fe2O4、(Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 )At least one of Fe2O4.

[0073] In some embodiments, steps S3 to S4 are repeated to achieve cyclic production of H2.

[0074] In some embodiments, a low temperature thermochemical cycle hydrogen production method comprises the following steps:

[0075] S1. placing an oxygen carrier on a porous sieve plate;

[0076] S2. Pass high-temperature flue gas into the outer barrel from the flue gas inlet. The high-temperature flue gas heats the inner barrel to ensure that the system reaches a reaction temperature of 750-800°C. After the reaction temperature stabilizes, pass N2 into the outer barrel from the flue gas inlet at a rate of 1000 mL min. -1 The air in the outer barrel was removed by flow, and then the N2 flow was adjusted to 800 mL min -1 ;

[0077] S3, introducing a mixed gas of CH4 and N2 into the inner barrel through the reaction gas inlet pipe, and stopping introducing the mixed gas after reacting with the oxygen carrier for 5.5 hours; CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas;

[0078] S4, by introducing N2 into the reaction gas inlet pipe at 1000mL min -1 The reaction system was purged with a flow rate of 1000 mL / min until the concentration of each component in the gas analyzer dropped below 0.5%. Then the N2 flow rate was adjusted to 800 mL / min. -1 , until the synthesis gas and unreacted CH4 and N2 in the inner barrel are discharged;

[0079] S5, introducing water vapor (650°C) into the inner barrel from the reaction gas inlet pipe, and then being heated to 800°C by the high-temperature flue gas, and then the high-temperature water vapor contacts with the oxygen carrier through the porous sieve plate to generate H2, and the generated H2 and the remaining water vapor enter the H2 collecting device from the reaction gas outlet pipe via the condensing device;

[0080] S6. The oxygen carrier reacting with water vapor is regenerated, and steps S3 to S5 are repeated to achieve intermittent carbon capture and hydrogen production.

[0081] In some embodiments, the mass of the oxygen carrier is 1 kg, CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas, and the reaction time is 325 to 605 minutes; water vapor (650°C) is introduced into the inner barrel through the reaction gas inlet pipe, and then heated to 800°C by the high-temperature flue gas, and then the high-temperature water vapor contacts with the oxygen carrier through a porous sieve plate to generate H2, and the reaction time is 325 to 407 minutes.

[0082] The low-temperature thermochemical cycle water decomposition hydrogen production method of the present invention adopts cheap and easily available high-temperature flue gas as a heat source, saving unnecessary energy expenses; the gas path of the high-temperature flue gas is changed through the first / second baffle plate to achieve maximum utilization of the heat source; the use of oxygen carriers reduces the temperature in the thermochemical cycle water decomposition hydrogen production process, and the use of additional baffles further reduces the reaction temperature, reduces the maintenance cost of the device and the energy consumption during operation, and improves the stability of the device; the output of green hydrogen can be achieved during the reaction process.

[0083] The following further illustrates the low-temperature thermochemical cycle water decomposition hydrogen production method of the present application with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0084] In the following embodiments, the syngas yield refers to the amount of syngas produced per unit volume of fuel (fuel refers to CH4) in the chemical loop reforming process; the syngas purity refers to the percentage of the amount of syngas in the total amount of gas; the H2 yield refers to the amount of H2 obtained per unit mass of oxygen carrier in the chemical loop water decomposition process to produce hydrogen; the H2 purity refers to the percentage of the amount of H2 in the total amount of gas.

[0085] Example 1

[0086] This embodiment provides a method for producing hydrogen by decomposing water through a thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, and includes the following steps:

[0087] S1, oxygen carrier NiFe2O4, SrFe 12 O 19 A total of 1 kg was placed on a porous sieve plate, NiFe2O4, SrFe 12 O 19 The molar ratio is 0.3:0.7;

[0088] S2, passing high-temperature (1000°C) flue gas into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 800°C, stopping the introduction of high-temperature flue gas, and passing N2 into the outer barrel from the flue gas inlet to remove the air in the outer barrel;

[0089] A mixed gas of CH4 and N2 is introduced into the inner barrel from the reaction gas inlet pipe. CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas. The flow rate of CH4 is 500 mL min -1 , the flow rate of N2 is 500 mL min -1 , the reaction time is 325min;

[0090] S3, by introducing N2 into the reaction gas inlet pipe, the synthesis gas and unreacted CH4 and N2 in the inner barrel are discharged;

[0091] Water vapor (650°C) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800°C by the high-temperature flue gas. The high-temperature water vapor then contacts the oxygen carrier through the porous sieve plate to generate H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration; the water vapor flow rate is 210 mL·min -1 , the reaction time is 325min;

[0092] S4, repeating steps S2 to S3 to perform cyclic hydrogen production;

[0093] The preparation method of the oxygen carrier NiFe2O4 comprises the following steps:

[0094] S11. Place Ni(NO3)2 and Fe(NO3)2 in a grinding device, add deionized water, and grind at 300 r·min -1 The sample was ground at a speed of 4 h; after grinding, it was transferred to an oven at 110°C for drying to remove excess water to obtain a precursor; the molar ratio of Ni(NO3)2 to Fe(NO3)2 was 1:2, and the mass of water was 1% of the mass of Ni(NO3)2;

[0095] S12, place the precursor in a crucible and transfer it to a muffle furnace at 3℃·min -1 The sample is heated to 1000°C at a heating rate and maintained at this temperature for 10 hours; finally, the sample is taken out after cooling, ground and sieved, and powder with a particle size of less than 400μm is obtained to obtain the oxygen carrier NiFe2O4.

[0096] Oxygen carrier SrFe 12 O 19 The preparation method comprises the following steps:

[0097] S11. Place SrCO3 and Fe(NO3)2 in a grinding device, add deionized water, and grind at 300 r·min -1 The sample was ground at a speed of 4 h; after grinding, it was transferred to an oven at 110°C for drying to remove excess water to obtain a precursor; the molar ratio of SrCO3 to Fe(NO3)2 was 1:12, and the mass of water was 1% of the mass of SrCO3;

[0098] S12, place the precursor in a crucible and transfer it to a muffle furnace at 3℃·min -1 The sample was heated to 1000°C at a heating rate of 1000°C and kept at this temperature for 10 hours. Finally, the sample was taken out after cooling, ground and sieved, and powder with a particle size of less than 400 μm was obtained to obtain the oxygen carrier SrFe 12 O 19 .

[0099] In the first cycle, the synthesis gas yield was 1.21 mmol g -1 , purity was 79.13%, H2 yield was 6.02mmol·g -1 The H2 yield was 97.96% pure; the synthesis gas yield of the fifth cycle was 1.83 mmol·g -1 , purity was 81.50%, H2 yield was 9.52mmol·g -1 , with a purity of 97.94%.

[0100] Example 2

[0101] This embodiment provides a method for producing hydrogen by decomposing water through a thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, and includes the following steps:

[0102] S1, 1kg oxygen carrier Ca2Ni 0.75 Fe 1.25 O5 is placed on a porous sieve plate;

[0103] S2, passing high-temperature (1000°C) flue gas into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 800°C, stopping the introduction of high-temperature flue gas, and passing N2 into the outer barrel from the flue gas inlet to remove the air in the outer barrel;

[0104] A mixed gas of CH4 and N2 is introduced into the inner barrel from the reaction gas inlet pipe. CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas. The flow rate of CH4 is 500 mL min -1 , the flow rate of N2 is 500 mL min -1 , the reaction time is 421min;

[0105] S3, by introducing N2 into the reaction gas inlet pipe, the synthesis gas and unreacted CH4 and N2 in the inner barrel are discharged;

[0106] Water vapor (650°C) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800°C by the high-temperature flue gas. The high-temperature water vapor then contacts the oxygen carrier through the porous sieve plate to generate H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration; the water vapor flow rate is 210 mL min -1 , the reaction time is 371min;

[0107] S4, repeating steps S2 to S3 to perform cyclic hydrogen production;

[0108] Oxygen carrier Ca2Ni 0.75 Fe 1.25 The preparation method of O5 comprises the following steps:

[0109] S11. Place Ni(NO3)2, Ca(NO3)2 and Fe(NO3)2 in a grinding device, add deionized water and grind at 300 r·min -1 The sample was ground at a speed of 4 hours; after grinding, it was transferred to an oven at 110°C for drying to remove excess water to obtain a precursor; the molar ratio of Ni(NO3)2, Ca(NO3)2, and Fe(NO3)2 was 0.75:2:1.25, and the mass of water was 1.5% of the mass of Ni(NO3)2;

[0110] S12, place the precursor in a crucible and transfer it to a muffle furnace at 3℃·min -1 The sample was heated to 1000°C at a heating rate of 1000°C and kept at this temperature for 10 hours. Finally, the sample was taken out after cooling, ground and sieved, and powder with a particle size of less than 400 μm was obtained to obtain the oxygen carrier Ca2Ni 0.75 Fe 1.25 O5.

[0111] In the first cycle, the synthesis gas yield was 2.28 mmol·g -1 , purity is 88.56%; H2 yield is 4.48mmol·g -1 , purity is 84.07%; the fifth cycle synthesis gas yield is 2.26mmol·g -1 , purity is 95.19%; H2 yield is 0.97mmol·g -1 , with a purity of 69.37%.

[0112] Example 3

[0113] This embodiment provides a method for producing hydrogen by decomposing water through a thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, and includes the following steps:

[0114] S1, 1kg oxygen carrier (Ni 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )Fe2O4 is placed on a porous sieve plate;

[0115] S2, passing high-temperature (1000°C) flue gas into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 800°C, stopping the introduction of high-temperature flue gas, and passing N2 into the outer barrel from the flue gas inlet to remove the air in the outer barrel;

[0116] A mixed gas of CH4 and N2 is introduced into the inner barrel from the reaction gas inlet pipe. CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas. The flow rate of CH4 is 500 mL min -1 , the flow rate of N2 is 500 mL min -1 , the reaction time is 605min;

[0117] S3, by introducing N2 into the reaction gas inlet pipe, the synthesis gas and unreacted CH4 and N2 in the inner barrel are discharged;

[0118] Water vapor (650°C) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800°C by the high-temperature flue gas. The high-temperature water vapor then contacts the oxygen carrier through the porous sieve plate to generate H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration; the water vapor flow rate is 210 mL min -1 , the reaction time is 325min;

[0119] S4, repeating steps S2 to S3 to perform cyclic hydrogen production;

[0120] Oxygen carrier (Ni 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )The preparation method of Fe2O4 comprises the following steps:

[0121] S11. Place Ni(NO3)2, Co(NO3)2, Ca(NO3)2, Cu(NO3)2, Mg(NO3)2 and Fe(NO3)2 in a grinding device, add deionized water and grind at 300 r·min -1The sample was ground at a speed of 4 h; after grinding, it was transferred to an oven at 110°C for drying to remove excess water to obtain a precursor; the molar ratio of Ni(NO3)2, Co(NO3)2, Ca(NO3)2, Cu(NO3)2, Mg(NO3)2, and Fe(NO3)2 was 0.2:0.2:0.2:0.2:0.2:2, and the mass of water was 2% of the mass of Ni(NO3)2;

[0122] S12, place the precursor in a crucible and transfer it to a muffle furnace at 3℃·min -1 The sample was heated to 1000°C at a heating rate of 1000°C and kept at this temperature for 10 h. Finally, the sample was taken out after cooling, ground and sieved, and powder with a particle size of less than 400 μm was obtained to obtain the oxygen carrier (Ni 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )Fe2O4.

[0123] In the first cycle, the synthesis gas yield was 1.44 mmol g -1 , purity is 77.42%; H2 yield is 9.27mmol·g -1 , purity is 99.12%; the fifth cycle synthesis gas yield is 1.76mmol·g -1 , purity is 81.96%; H2 yield is 11.13mmol·g -1 , with a purity of 97.09%.

[0124] Example 4

[0125] This embodiment provides a method for producing hydrogen by decomposing water through a thermochemical cycle, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, and includes the following steps:

[0126] S1, 1kg oxygen carrier (Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 )Fe2O4 is placed on a porous sieve plate;

[0127] S2, passing high-temperature (1000°C) flue gas into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 800°C, stopping the introduction of high-temperature flue gas, and passing N2 into the outer barrel from the flue gas inlet to remove the air in the outer barrel;

[0128] A mixed gas of CH4 and N2 is introduced into the inner barrel from the reaction gas inlet pipe. CH4 captures the lattice oxygen in the oxygen carrier, the oxygen carrier is reduced, and CH4 is converted into synthesis gas. The flow rate of CH4 is 500 mL min-1 , the flow rate of N2 is 500 mL min -1 , the reaction time is 422min;

[0129] S3, by introducing N2 into the reaction gas inlet pipe, the synthesis gas and unreacted CH4 and N2 in the inner barrel are discharged;

[0130] Water vapor (650°C) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800°C by the high-temperature flue gas. The high-temperature water vapor then contacts the oxygen carrier through the porous sieve plate to generate H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration; the water vapor flow rate is 210 mL min -1 , the reaction time is 407min;

[0131] S4, repeating steps S2 to S3 to perform cyclic hydrogen production;

[0132] Oxygen carrier (Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 )The preparation method of Fe2O4 comprises the following steps:

[0133] S11. Place Cr(NO3)3, Mn(NO3)2, Co(NO3)2, Ni(NO3)2, Mg(NO3)2 and Fe(NO3)2 in a grinding device, add deionized water and grind at 300 r·min -1 The sample was ground at a speed of 4 h; after grinding, it was transferred to an oven at 110°C for drying to remove excess water to obtain a precursor; the molar ratio of Cr(NO3)3, Mn(NO3)2, Co(NO3)2, Ni(NO3)2, Mg(NO3)2, and Fe(NO3)2 was 0.2:0.2:0.2:0.2:0.2:2, and the mass of water was 2% of the mass of Cr(NO3)3;

[0134] S12, place the precursor in a crucible and transfer it to a muffle furnace at 3℃·min -1 The sample was heated to 1000°C at a heating rate and kept at this temperature for 10 h. Finally, the sample was taken out after cooling, ground and sieved, and the powder with a particle size of less than 400 μm was obtained to obtain the oxygen carrier (Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 )Fe2O4.

[0135] In the first cycle, the synthesis gas yield was 1.80 mmol·g -1, purity is 83.14%; H2 yield is 8.59mmol·g -1 , purity is 97.93%; the fifth cycle synthesis gas yield is 1.97mmol·g -1 , purity is 84.91%; H2 yield is 9.37mmol·g -1 , with a purity of 95.33%.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-temperature thermochemical cycle water decomposition hydrogen production device, characterized in that: include: The outer barrel is hollow inside and has a smoke inlet at one end and a smoke outlet at the other end; An inner barrel, which is located inside the outer barrel, and a porous sieve plate is provided inside the inner barrel for carrying oxygen carriers; A plurality of heat exchange tubes are arranged in the outer barrel at locations corresponding to the smoke inlet, and one end of the heat exchange tube extends toward the end of the inner barrel close to the smoke inlet and is connected to the inner barrel; The reaction gas inlet pipe is located in the outer barrel, the end of the reaction gas inlet pipe close to the heat exchange pipe is connected to the heat exchange pipe, and the end away from the heat exchange pipe extends toward the end of the outer barrel close to the flue gas inlet and passes through the outer barrel.

2. The low-temperature thermochemical cycle water decomposition hydrogen production device according to claim 1, characterized in that: The end of the inner barrel away from the heat exchange tube extends toward the end of the outer barrel close to the smoke outlet and passes through the outer barrel. The end of the inner barrel located outside the outer barrel is provided with a reaction gas outlet pipe.

3. The low-temperature thermochemical cycle water decomposition hydrogen production device according to claim 1, characterized in that: A plurality of first baffles are arranged in the outer barrel at locations corresponding to the heat exchange tubes, and two adjacent first baffles are arranged alternately. After the heat exchange tubes pass through the plurality of first baffles, the two ends thereof are respectively connected to the reaction gas inlet pipe and the inner barrel.

4. The low-temperature thermochemical cycle water decomposition hydrogen production device according to claim 1, characterized in that: An oxygen carrier feeding pipe is arranged at a position of the inner barrel corresponding to the porous sieve plate, and the oxygen carrier feeding pipe passes through the outer barrel.

5. The low-temperature thermochemical cycle water decomposition hydrogen production device according to claim 1, characterized in that: A second baffle is provided in the outer barrel at a position corresponding to the inner barrel, two adjacent second baffles are arranged alternately, and the inner barrel passes through a plurality of the second baffles in sequence.

6. The low-temperature thermochemical cycle water decomposition hydrogen production device according to claim 1, characterized in that: The end of the inner barrel close to the reaction gas outlet pipe is provided with a heat insulation plug; The inner barrel is provided with a temperature sensor for monitoring the temperature of the oxygen carrier; The outer periphery of the outer barrel is also provided with ear seats and expansion joints.

7. A method for producing hydrogen by decomposing water through a low-temperature thermochemical cycle, using the low-temperature thermochemical cycle water decomposition hydrogen production device as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1. placing an oxygen carrier on a porous sieve plate; S2, passing high-temperature flue gas into the outer barrel from the flue gas inlet, so that the temperature inside the inner barrel is 750-800°C; S3, passing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, the oxygen carrier is reduced, and CH4 is converted into synthesis gas; S4. After the synthesis gas and unreacted CH4 and N2 in the inner barrel are removed, high-temperature flue gas is used again to make the temperature in the inner barrel reach 750-800°C, and then water vapor is introduced into the inner barrel through the reaction gas inlet pipe. The water vapor reacts with the reduced oxygen carrier to produce H2. The oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration.

8. The method for producing hydrogen by decomposing water using a low-temperature thermochemical cycle as claimed in claim 7, characterized in that: The oxygen carrier comprises at least one of nickel-doped brownmillerite, composite metal oxide, and high entropy spinel oxide; In the step of introducing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, the flow rate of CH4 is 500-550 mL·min -1 , the flow rate of N2 is 500~550mL·min -1 ; In the step of introducing water vapor into the inner barrel from the reaction gas inlet pipe, the flow rate of water vapor is 200-250 mL min -1 , the temperature of water vapor is 600-650℃.

9. The method for producing hydrogen by decomposing water using a low-temperature thermochemical cycle as claimed in claim 7, characterized in that: The high-temperature flue gas is introduced into the outer barrel from the flue gas inlet to make the temperature in the inner barrel reach 750-800°C, and the introduction of the high-temperature flue gas is stopped. N2 is introduced into the outer barrel from the flue gas inlet to remove the air in the outer barrel, and then the synthesis gas reaction is carried out; wherein the flow rate of N2 is 500-100 mL·min -1 ; The synthesis gas and unreacted CH4 and N2 in the inner barrel are removed by introducing N2 into the reaction gas inlet pipe, wherein the flow rate of N2 is 500-100 mL min -1 .

10. The method for producing hydrogen by decomposing water using a low-temperature thermochemical cycle as claimed in claim 8, characterized in that: The nickel-doped calcium iron ore is Ca2Ni 0.75 Fe 1.25 O5; The composite metal oxide includes NiFe2O4, SrFe 12 O 19 At least one of; The high entropy spinel oxide comprises (Ni 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )Fe2O4、(Cr 0.2 Mn 0.2 Co 0.2 Ni 0.2 Mg 0.2 ) at least one of Fe2O4; Repeat the cycle steps S3 to S4 to achieve the cyclic preparation of H2.

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