A device and method for producing hydrogen by low-temperature thermochemical water splitting

Abstract

The application provides a low-temperature thermo-chemical cycle water decomposition hydrogen production device and method. The low-temperature thermo-chemical cycle water decomposition hydrogen production device of the application is provided with a flue gas inlet for introducing high-temperature flue gas generated by biomass pyrolysis and making the flue gas face the heat exchange tube to realize efficient heat transfer. Meanwhile, the device is provided with a reaction gas inlet pipe at the bottom and connected with the heat exchange tube, the high-temperature flue gas is exchanged with water vapor, and the reaction temperature is effectively controlled within 800 DEG C, thereby overcoming the defects of high energy consumption, unstable operation and high maintenance cost of the traditional chemical cycle hydrogen production device. The low-temperature thermo-chemical cycle water decomposition hydrogen production method of the application uses cheap and easily available high-temperature flue gas as a heat source, thereby saving unnecessary energy consumption. The first / second baffle changes the gas path of the high-temperature flue gas to realize maximum utilization of the heat source. In combination with the use of oxygen carriers, the temperature in the process of thermo-chemical cycle water decomposition hydrogen production is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production, and particularly relates to a low-temperature thermochemical cycle water decomposition hydrogen production device and a hydrogen production method. BACKGROUND

[0002] In recent years, the thermochemical cycle water decomposition hydrogen production technology has attracted extensive attention due to its high efficient green hydrogen production capacity and relatively low reaction temperature. However, the thermodynamic property of water is relatively stable, so the thermochemical cycle water decomposition hydrogen production needs to be carried out at 1500℃. At this temperature, the conventional thermochemical cycle water decomposition hydrogen production device not only has high energy consumption and high maintenance cost, but also has poor device stability.

[0003] At present, there are few and immature devices designed for fuel-assisted thermochemical cycle water decomposition hydrogen production. Therefore, it is of great significance to develop a new type of fuel-assisted thermochemical cycle water decomposition hydrogen production device to reduce cost and energy consumption. SUMMARY

[0004] The application aims at the above technical problems, and provides a low-temperature thermochemical cycle water decomposition hydrogen production device and a hydrogen production method. The device is used for introducing high-temperature flue gas (1000℃) generated by biomass pyrolysis and making the flue gas face the heat exchange pipe to realize efficient heat transfer through the setting of a flue gas inlet. At the same time, a reaction gas inlet pipe is arranged at the bottom of the device and directly connected with the heat exchange pipe to pass in water vapor with a temperature of 650℃. In order to further optimize the heat exchange effect, a first baffle is arranged in the device to enhance the heat exchange efficiency of the high-temperature flue gas and the water vapor. The device effectively controls the reaction temperature within 800℃, thereby overcoming the disadvantages of high energy consumption, unstable operation and high maintenance cost of the traditional chemical cycle hydrogen production device.

[0005] In order to achieve the above purpose, the application adopts the following technical scheme:

[0006] In a first aspect, the application provides a low-temperature thermochemical cycle water decomposition hydrogen production device, which comprises:

[0007] An outer barrel, which is hollow inside, is provided with a flue gas inlet at one end and a flue gas outlet at the other end;

[0008] An inner barrel, which is located inside the outer barrel, is provided with a porous sieve plate inside to carry an oxygen carrier;

[0009] A plurality of heat exchange pipes, which are arranged in the outer barrel corresponding to the flue gas inlet, extend towards the end of the inner barrel close to the flue gas inlet and communicate with the inner barrel at one end;

[0010] A reaction gas inlet pipe, which is located in the outer barrel, communicates with the heat exchange pipe at the end close to the heat exchange pipe and extends towards the end of the outer barrel close to the flue gas inlet and penetrates out of the outer barrel at the end away from the heat exchange pipe.

[0011] Preferably, the inner barrel extends towards the end of the outer barrel close to the flue gas outlet and penetrates out of the outer barrel, and the end of the inner barrel located outside the outer barrel is provided with a reaction gas outlet pipe.

[0012] Preferably, a plurality of first baffles are arranged in the outer barrel corresponding to the heat exchange pipes, and adjacent two first baffles are arranged staggered, and the heat exchange pipes penetrate through the plurality of first baffles and are respectively connected to the reaction gas inlet pipe and the inner barrel at both ends.

[0013] Preferably, the inner barrel is provided with an oxygen carrier feeding pipe corresponding to the porous sieve plate, and the oxygen carrier feeding pipe penetrates out of the outer barrel.

[0014] Preferably, a plurality of second baffles are arranged in the outer barrel corresponding to the inner barrel, and adjacent two second baffles are arranged staggered, and the inner barrel penetrates through the plurality of second baffles in sequence.

[0015] Preferably, the end of the inner barrel close to the reaction gas outlet pipe is provided with a heat insulation plug.

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

[0017] The outer barrel is further provided with an ear seat and an expansion joint.

[0018] In a second aspect, the present application also provides a low-temperature thermo-chemical cycle water decomposition hydrogen production method, which is prepared by using the low-temperature thermo-chemical cycle water decomposition hydrogen production device, and comprises the following steps:

[0019] S1, placing the oxygen carrier on the porous sieve plate;

[0020] S2, passing the high-temperature flue gas into the outer barrel through the flue gas inlet, so that the temperature in the inner barrel is 750-800℃;

[0021] S3, passing the mixed gas of CH4 and N2 into the inner barrel through the reaction gas inlet pipe, so that 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 discharged, the temperature in the inner barrel is again raised to 750-800℃ by using high-temperature flue gas, and then water vapor is passed into the inner barrel through the reaction gas inlet pipe, so that the water vapor reacts with the reduced oxygen carrier to produce H2, and the oxygen carrier after steam oxidation is regenerated.

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

[0024] The flow rate of CH4 is 500-550 mL·min -1 , and the flow rate of N2 is 500-550 mL·min -1 .

[0025] The flow rate of water vapor is 200-250 mL·min -1 , and the temperature of water vapor is 600-650℃.

[0026] Preferably, the high-temperature flue gas is introduced into the outer barrel through the flue gas inlet, so that the temperature in the inner barrel is 750-800℃, the introduction of the high-temperature flue gas is stopped, N2 is introduced into the outer barrel through the flue gas inlet to remove the air in the outer barrel, and then the synthesis gas reaction is carried out again; 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 brownmillerite is Ca2Ni 0.75 Fe 1.25 O5.

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

[0030] The high-entropy spinel oxide includes at least one of (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 )Fe2O4.

[0031] The steps S3-S4 are repeated to realize the cyclic preparation of H2.

[0032] The low-temperature thermochemical cyclic water decomposition hydrogen production device of the present application has the following

[0033] beneficial effects:

[0034] 1. The low-temperature thermo-chemical cycle water decomposition hydrogen production device of the present application, by setting the flue gas inlet, for introducing the high-temperature flue gas (1000℃) generated by biomass pyrolysis, and making it face the heat exchange pipe, to realize efficient heat transfer; at the same time, the device bottom is provided with a reaction gas inlet pipe, which is directly connected with the heat exchange pipe, and the temperature of the water vapor is 650℃, the high-temperature flue gas is exchanged with the water vapor, and the reaction temperature is effectively controlled within 800℃, so as to overcome the disadvantages of high energy consumption, unstable operation and high maintenance cost of traditional chemical cycle hydrogen production device;

[0035] 2. The low-temperature thermo-chemical cycle water decomposition hydrogen production device of the present application, a plurality of first baffles are arranged at the corresponding heat exchange pipe in the outer barrel, and the adjacent two first baffles are staggered; the staggered arrangement of the first baffles makes the high-temperature flue gas flow in the outer barrel in the shape of "S", and the high-temperature flue gas heats the water vapor in the heat exchange pipe, greatly increasing the heat exchange efficiency of the flue gas and the water vapor;

[0036] 3. The low-temperature thermo-chemical cycle water decomposition hydrogen production method of the present application, which uses cheap and easily available high-temperature flue gas as heat source, saves unnecessary energy consumption; by changing the gas path of high-temperature flue gas through the first / second baffle, the heat source is used to the maximum extent; in combination with the use of oxygen carrier, the temperature in the process of thermo-chemical cycle water decomposition hydrogen production is reduced, the use of additional baffles further reduces the reaction temperature, reduces the maintenance cost and energy consumption of the device during operation, and improves the stability of the device; green hydrogen can be produced in the reaction process. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description, and obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0038] Fig. 1 It is a structure diagram of the low-temperature thermo-chemical cycle water decomposition hydrogen production device in one of the embodiments of the present application.

[0039] Fig. 2 It is a top view of the low-temperature thermo-chemical cycle water decomposition hydrogen production device in one of the embodiments of the present application. DETAILED DESCRIPTION

[0040] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] In the description of the present application, it should be understood that the relative or positional relationship indicated by terms such as "upper" is based on the relative or positional relationship shown in the drawings, or the relative or positional relationship commonly used when the product of the present application is used, or the relative or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0042] In addition, the terms "first", "second", and the like are only used for differentiation in description and cannot be understood as indicating or implying relative importance.

[0043] In order to better understand the present application without limiting the scope of the present application, all numbers, percentages and other numerical values used in this application to express amounts, percentages and the like should be understood as being modified by the word "about" in all cases. Therefore, unless specifically stated otherwise, the numerical parameters listed in the specification and the attached claims are approximations. They can vary depending on different desired properties to be achieved. Each numerical parameter should be considered at least as being obtained from the reported significant digits and by rounding off methods commonly used by those skilled in the art.

[0044] It should be noted that the sequence of the following embodiments is not limited as the preferred sequence of the embodiments. In addition, in the description of the present application, the term "comprising" means "including but not limited to". Various embodiments of the present application can exist in a range form; it should be understood that the description in a range form is only for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single 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 range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it means that any cited number (fraction or integer) within the indicated range is included.

[0045] The present application provides a low-temperature thermochemical cycle water decomposition hydrogen production device, as shown inFigs. 1-2 The application is shown as follows:

[0046] The outer barrel 1 is internally hollow, and is provided with a flue gas inlet 11 at one end and a flue gas outlet 12 at the other end;

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

[0048] A plurality of heat exchange pipes 3 are arranged in the outer barrel 1 corresponding to the flue gas inlet 11, and one end of the heat exchange pipe 3 extends towards the end of the inner barrel 2 close to the flue gas inlet 11 and communicates with the inner barrel 2;

[0049] The reaction gas inlet pipe 4 is located in the outer barrel 1, and the end of the reaction gas inlet pipe 4 close to the heat exchange pipe 3 communicates with the heat exchange pipe 3, and the end of the reaction gas inlet pipe 4 away from the heat exchange pipe extends towards the end of the outer barrel 1 close to the flue gas inlet 11 and penetrates out of the outer barrel 1.

[0050] The low-temperature thermo-chemical cycle water decomposition hydrogen production device of the application comprises an outer barrel 1, an inner barrel 2, a plurality of heat exchange pipes 3 and a reaction gas inlet pipe 4; the outer barrel 1 and the inner barrel 2 are both hollow barrel structures in the shape of a cylinder; 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 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 is provided with a porous sieve plate 21 inside, and an oxygen carrier 26 is arranged on the porous sieve plate 2; a plurality of heat exchange pipes 3 are arranged in the outer barrel 1 corresponding to the flue gas inlet 11, and the upper end of the heat exchange pipe 3 communicates with the bottom of the inner barrel 2, and the lower end of the heat exchange pipe 3 communicates with the reaction gas inlet pipe 4, and the lower end of the reaction gas inlet pipe 4 extends downwards and penetrates out of the outer barrel 1.

[0051] The low-temperature thermo-chemical cycle water decomposition hydrogen production device of the application is provided with a flue gas inlet for introducing high-temperature flue gas (1000℃) generated by biomass pyrolysis and making it face the heat exchange pipe to realize efficient heat transfer; at the same time, the device is provided with a reaction gas inlet pipe at the bottom and is directly connected with the heat exchange pipe, and water vapor with a temperature of 650℃ is introduced, the high-temperature flue gas is heat-exchanged with the water vapor, and the reaction temperature is effectively controlled within 800℃, thereby overcoming the defects of high energy consumption, unstable operation and high maintenance cost of the traditional chemical cycle hydrogen production device.

[0052] In some embodiments, the end of the inner barrel 2 away from the heat exchange pipe extends towards the end of the outer barrel 1 close to the flue gas outlet 12 and penetrates out of the outer barrel 1, and the end of the inner barrel 2 located outside the outer barrel 1 is provided with a reaction gas outlet pipe 22. Specifically, the mixed gas of CH4 and N2 is introduced 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 introduced into the inner barrel 2 through the reaction gas inlet pipe 4, the water vapor reacts with the reduced oxygen carrier to produce H2, and the H2 is discharged through the reaction gas outlet pipe 22.

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

[0054] In some embodiments, the inner barrel 2 is provided with an oxygen carrier feeding pipe 23 corresponding to the porous sieve plate 21, and the oxygen carrier feeding pipe 23 penetrates out of the outer barrel 1. The oxygen carrier feeding pipe 23 can be used to add oxygen carriers to the porous sieve plate 21 of the inner barrel 2.

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

[0056] In some embodiments, the inner barrel 2 is provided with a heat insulation plug 24 near the end of the reaction gas outlet pipe 22.

[0057] In some embodiments, a temperature sensor 25 is arranged on the inner barrel 2 to monitor the temperature of the oxygen carrier. Specifically, the temperature sensor 25 extends into the inner barrel 2 after penetrating through the heat insulation plug 24 to monitor the temperature in the inner barrel 2.

[0058] In some embodiments, 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 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 application also provides a low-temperature thermochemical cycle water decomposition hydrogen production method, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device and includes the following steps:

[0060] S1, placing the oxygen carrier on the porous sieve plate;

[0061] S2, introducing high-temperature flue gas into the outer barrel through the flue gas inlet, so that the temperature in the inner barrel is 750-800℃;

[0062] S3, introducing a mixed gas of CH4 and N2 into the inner barrel through the reaction gas inlet pipe, CH4 takes 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, N2 in the inner barrel are discharged, high-temperature flue gas is used again to make the temperature in the inner barrel 750-800℃, then water vapor is introduced into the inner barrel from the reaction gas inlet pipe, the water vapor reacts with the reduced oxygen carrier to produce H2, and the oxygen carrier after steam oxidation obtains lattice oxygen to achieve regeneration.

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

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

[0066] In the step of introducing the 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 , and the flow rate of N2 is 500-550 mL·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 , and the temperature of water vapor is 600-650℃.

[0068] In some embodiments, the high-temperature flue gas is introduced into the outer barrel from the flue gas inlet to make the temperature in the inner barrel 750-800℃, the introduction of high-temperature flue gas is stopped, N2 is introduced into the outer barrel from the flue gas inlet to discharge the air in the outer barrel, and then the synthesis gas reaction is performed again; wherein the flow rate of N2 is 500-100 mL·min -1 .

[0069] The synthesis gas and unreacted CH4, N2 in the inner barrel are discharged 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, the nickel-doped brownmillerite is Ca2Ni 0.75 Fe 1.25 O5.

[0071] The composite metal oxide refers to two or more metal oxides, including but not limited to at least one of NiFe2O4, SrFe 12 O 19 .

[0072] The high-entropy spinel oxide includes (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 )Fe2O4.

[0073] In some embodiments, the cycle steps S3-S4 are repeated to realize the cyclic production of H2.

[0074] In some embodiments, the low-temperature thermo-chemical cycle hydrogen production method comprises the following steps:

[0075] S1, placing the oxygen carrier on a porous sieve plate;

[0076] S2, passing high-temperature flue gas into the outer barrel from the flue gas inlet, and heating the inner barrel with the high-temperature flue gas to ensure that the system reaches a reaction temperature of 750-800°C; after the reaction temperature is stable, pass N2 into the outer barrel from the flue gas inlet at a flow rate of 1000 mL·min -1 ; then adjust the N2 flow rate to 800 mL·min -1 ;

[0077] S3, passing a mixture of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, and stopping the passage of the mixed gas after reacting with the oxygen carrier for 5.5 h; CH4 takes the lattice oxygen in the oxygen carrier, and the oxygen carrier is reduced, and CH4 is converted into synthesis gas;

[0078] S4, passing N2 into the reaction gas inlet pipe to purge the reaction system at a flow rate of 1000 mL·min -1 ; after the concentration of each component in the gas analyzer is reduced to below 0.5%, adjust the N2 flow rate to 800 mL·min -1 , until the synthesis gas and unreacted CH4 and N2 in the inner barrel are removed;

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

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

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

[0082] The low-temperature thermo-chemical cycle water decomposition hydrogen production method of the application uses cheap and readily available high-temperature flue gas as a heat source, saving unnecessary energy expenditure; by changing the gas path of the high-temperature flue gas through the first / second baffle, the heat source is used to the maximum extent; in combination with the use of the oxygen carrier, the temperature in the thermo-chemical cycle water decomposition hydrogen production process is reduced, the use of the additional baffle further reduces the reaction temperature, reduces the maintenance cost and energy consumption of the device during operation, and at the same time improves the stability of the device; green hydrogen can be produced during the reaction process.

[0083] The low-temperature thermo-chemical cycle water decomposition hydrogen production method of the application is further illustrated in the following specific embodiments. This part further illustrates the content of the application in combination with specific embodiments, but should not be understood as a limitation of the application. If not specifically stated, the technical means used in the embodiments are conventional means known to those skilled in the art. Unless specifically stated, the reagents, methods and equipment used in the application 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 looping reforming process; the syngas purity refers to the percentage of the amount of syngas to the total amount of gas; the H2 yield refers to the amount of H2 obtained per unit mass of oxygen carrier in the chemical cycle water decomposition hydrogen production process; and the H2 purity refers to the percentage of the amount of H2 to the total amount of gas.

[0085] Example 1

[0086] The embodiment provides a thermo-chemical cycle water decomposition hydrogen production method, which is prepared by using the low-temperature thermo-chemical cycle water decomposition hydrogen production device, and comprises the following steps:

[0087] S1, placing 1 kg of oxygen carriers NiFe2O4 and SrFe 12 O 19 on the perforated sieve plate, the molar ratio of NiFe2O4 and SrFe 12 O 19 is 0.3:0.7;

[0088] S2, high-temperature (1000℃) flue gas is introduced into the outer barrel from the flue gas inlet, so that the temperature in the inner barrel is 800℃, 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;

[0089] The 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 , and the reaction time is 325 min;

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

[0091] Steam (650℃) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800℃ by high-temperature flue gas, and then the high-temperature steam contacts the oxygen carrier through the porous perforated plate to generate H2, and the oxygen carrier after steam oxidation obtains lattice oxygen and is regenerated; the flow rate of steam is 210 mL·min -1 , and the reaction time is 325 min;

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

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

[0094] S11, placing Ni(NO3)2 and Fe(NO3)2 in a grinding device, adding deionized water, and grinding at a speed of 300 r·min -1 for 4 h; after grinding, the obtained sample is transferred to an oven at 110℃ for drying treatment to remove excess water and obtain a precursor; the molar ratio of Ni(NO3)2 to Fe(NO3)2 is 1:2, and the mass of water is 1% of the mass of Ni(NO3)2;

[0095] S12, placing the precursor in a crucible and transferring it to a muffle furnace, heating the sample to 1000℃ at a heating rate of 3℃·min -1 , and keeping the temperature for 10 h; finally, the sample is taken out after cooling, ground and sieved, and the powder with a particle size below 400 μm is obtained, that is, the oxygen carrier NiFe2O4.

[0096] The preparation method of the oxygen carrier SrFe 12 O 19 includes the following steps:

[0097] S11, SrCO3 and Fe(NO3)2 were placed in a grinding device, and deionized water was added, and the grinding was carried out at a rotation speed of 300 r·min -1 for 4 h; after the grinding was completed, the obtained sample was transferred to an oven at 110℃ for drying treatment to remove excess water to obtain a precursor; the molar ratio of SrCO3 and Fe(NO3)2 was 1:12, and the mass of water was 1% of the mass of SrCO3;

[0098] S12, the precursor was placed in a crucible and transferred to a muffle furnace, and the sample was heated to 1000℃ at a heating rate of 3℃·min -1 , and kept at this temperature for 10 h; finally, after the sample was cooled, it was taken out, ground and sieved, and the powder with a particle size below 400 μm was obtained, that is, the oxygen carrier SrFe 12 O 19 .

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

[0100] Example 2

[0101] The present embodiment provides a method for preparing hydrogen by thermochemical cycle decomposition of water, which is prepared by using the low-temperature thermochemical cycle water decomposition hydrogen production device, and comprises the following steps:

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

[0103] S2, high-temperature (1000℃) flue gas was introduced into the outer barrel from the flue gas inlet to make the temperature in the inner barrel 800℃, and the introduction of high-temperature flue gas was stopped, and N2 was introduced into the outer barrel from the flue gas inlet to remove the air in the outer barrel;

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

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

[0106] Water vapor (650℃) is introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800℃ by high-temperature flue gas, and then the high-temperature water vapor contacts the oxygen carrier through the perforated sieve plate to generate H2, and the oxygen carrier after steam oxidation is regenerated to obtain lattice oxygen; the water vapor flow is 210 mL·min -1 , and the reaction time is 371 min;

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

[0108] The oxygen carrier Ca2Ni 0.75 Fe 1.25 The preparation method of the oxygen carrier Ca2Ni

[0109] S11, placing Ni(NO3)2, Ca(NO3)2, Fe(NO3)2 in a grinding device, and adding deionized water, and grinding at a speed of 300 r·min -1 for 4 h; after grinding, the obtained sample is transferred to an oven at 110℃ for drying treatment to remove excess water to obtain a precursor; the molar ratio of Ni(NO3)2, Ca(NO3)2, Fe(NO3)2 is 0.75:2:1.25, and the mass of water is 1.5% of the mass of Ni(NO3)2;

[0110] S12, placing the precursor in a crucible and transferring it to a muffle furnace, heating the sample to 1000℃ at a heating rate of 3℃·min -1 , and keeping it at this temperature for 10 h; finally, after the sample is cooled, it is taken out, ground and sieved, and the powder with a particle size below 400 μm is obtained, that is, the oxygen carrier Ca2Ni 0.75 Fe 1.25 O5.

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

[0112] Example 3

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

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

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

[0116] Passing a mixed gas of CH4 and N2 into the inner barrel from a reaction gas inlet pipe, CH4 takes 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 , and the reaction time is 605 min;

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

[0118] Passing water vapor (650 DEG C) into the inner barrel from the reaction gas inlet pipe, then heating the water vapor to 800 DEG C by high-temperature flue gas, then making the high-temperature water vapor contact with the oxygen carrier through the porous sieve plate to generate H2, and regenerating the oxygen carrier after steam oxidation to obtain lattice oxygen; the flow rate of the water vapor is 210 mL·min -1 , and the reaction time is 325 min;

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

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

[0121] S11, placing Ni(NO3)2, Co(NO3)2, Ca(NO3)2, Cu(NO3)2, Mg(NO3)2 and Fe(NO3)2 in a grinding device, and adding deionized water, at a speed of 300 r·min -1The sample was ground at a certain speed for 4 hours. After grinding, the sample was transferred to an oven at 110°C for drying to remove excess moisture and obtain the 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, heating at 3°C / min. -1 The sample was heated to 1000℃ at a specific heating rate and held at this temperature for 10 hours. Finally, after cooling, the sample was removed, ground, and sieved to obtain powder with a particle size below 400 μm, which was then used to obtain the oxygen support (Ni). 0.2 Co 0.2 Ca 0.2 Cu 0.2 Mg 0.2 )Fe2O4.

[0123] During the first cycle, the syngas yield was 1.44 mmol·g. -1 The purity was 77.42%; the H2 yield was 9.27 mmol·g. -1 The purity was 99.12%; the syngas yield in the fifth cycle was 1.76 mmol·g. -1 The purity was 81.96%; the H2 yield was 11.13 mmol·g. -1 The purity is 97.09%.

[0124] Example 4

[0125] This embodiment provides a thermochemical cycle water splitting method for hydrogen production, which uses the aforementioned low-temperature thermochemical cycle water splitting hydrogen production apparatus and includes the following steps:

[0126] S1, 1 kg of 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. High-temperature (1000℃) flue gas is introduced into the outer barrel through the flue gas inlet, so that the temperature inside the inner barrel is 800℃. Then, the high-temperature flue gas is stopped, and N2 is introduced into the outer barrel through the flue gas inlet to remove the air inside the outer barrel.

[0128] A mixture of CH4 and N2 gas is introduced into the inner tank through the reaction gas inlet pipe. CH4 removes lattice oxygen from the oxygen carrier, reducing the oxygen carrier and converting CH4 into syngas. The flow rate of CH4 is 500 mL / min.-1 The flow rate of N2 was 500 mL·min -1 The reaction time was 422 min.

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

[0130] Water vapor (650℃) was introduced into the inner barrel from the reaction gas inlet pipe, and then heated to 800℃ by high-temperature flue gas, and then the high-temperature water vapor contacted with the oxygen carrier through the perforated sieve plate to generate H2, and the oxygen carrier after steam oxidation was regenerated by obtaining lattice oxygen; the flow rate of water vapor was 210 mL·min -1 The reaction time was 407 min.

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

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

[0133] S11, Cr(NO3)3, Mn(NO3)2, Co(NO3)2, Ni(NO3)2, Mg(NO3)2 and Fe(NO3)2 were placed in a grinding device, and deionized water was added, and grinding was performed at a speed of 300 r·min -1 for 4 h; after grinding, the obtained sample was transferred to an oven at 110℃ for drying treatment 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, the precursor was placed in a crucible and transferred to a muffle furnace, and the sample was heated to 1000℃ at a heating rate of 3℃·min -1 , 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 below 400 μm was obtained, that is, 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 83.14%; H2yield 8.59 mmol.g -1 , purity 97.93%; fifth cycle syngas yield 1.97 mmol.g -1 , purity 84.91%; H2yield 9.37 mmol.g -1 , purity 95.33%.

[0136] The above description is merely preferred embodiments of the present application, but not to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the protection scope of the present application.

Claims

1. A method for producing hydrogen by low-temperature thermochemical water splitting cycle, which is prepared by using a low-temperature thermochemical water splitting cycle device, characterized in that the low-temperature thermochemical water splitting cycle device comprises: an outer barrel, which is hollow inside, and is provided with a flue gas inlet at one end and a flue gas outlet at the other end; an inner barrel, which is located inside the outer barrel and is provided with a porous sieve plate for loading an oxygen carrier; a plurality of heat exchange pipes, which are arranged in the outer barrel corresponding to the flue gas inlet, and one end of each of the heat exchange pipes extends towards the end of the inner barrel close to the flue gas inlet and communicates with the inner barrel; a reaction gas inlet pipe, which is located in the outer barrel, and one end of the reaction gas inlet pipe communicates with the heat exchange pipes close to the end of the heat exchange pipes, and the other end of the reaction gas inlet pipe extends towards the end of the outer barrel close to the flue gas inlet and penetrates out of the outer barrel; a plurality of first baffles are arranged in the outer barrel corresponding to the heat exchange pipes, and two adjacent first baffles are arranged alternately, and the heat exchange pipes penetrate through the plurality of first baffles and are respectively connected to the reaction gas inlet pipe and the inner barrel at two ends; a second baffle is arranged in the outer barrel corresponding to the inner barrel, and two adjacent second baffles are arranged alternately, and the inner barrel penetrates through the plurality of second baffles in sequence; the method for producing hydrogen by low-temperature thermochemical water splitting cycle comprises the following steps: S1, loading the oxygen carrier on the porous sieve plate; S2, passing high-temperature flue gas into the outer barrel from the flue gas inlet to make the temperature in the inner barrel 750-800℃; S3, passing a mixed gas of CH4 and N2 into the inner barrel from the reaction gas inlet pipe, so that 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 discharged, the temperature in the inner barrel is made 750-800℃ again by using high-temperature flue gas, and then water vapor is passed into the inner barrel from the reaction gas inlet pipe, so that the water vapor reacts with the reduced oxygen carrier to produce H2, and the oxygen carrier after steam oxidation is regenerated by obtaining lattice oxygen; the preparation method of the oxygen carrier NiFe2O4 comprises the following steps: repeating the steps S3-S4 to realize the cyclic production of H2. The end of the inner barrel away from the heat exchange pipes extends towards the end of the outer barrel close to the flue gas outlet and penetrates out of the outer barrel, and the end of the inner barrel located outside the outer barrel is provided with a reaction gas outlet pipe. The inner barrel is provided with an oxygen carrier feeding pipe corresponding to the porous sieve plate, and the oxygen carrier feeding pipe penetrates out of the outer barrel. 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 barrel is further provided with an ear seat and an expansion joint. ​ ​ ​ ​ ​ ​ ​ The oxygen carrier is NiFe2O4, SrFe 12 O 19 The oxygen carrier is NiFe2O4, SrFe 12 O 19 The molar ratio of NiFe2O4, SrFe The flow rate of CH4 is 500-550 mL·min -1 , and the flow rate of N2 is 500-550 mL·min -1 . The water vapor is introduced into the inner barrel from the reaction gas inlet pipe at a flow rate of 200-250 mL·min -1 and a temperature of 600-650℃. ​ S11, Ni(NO3)2, Fe(NO3)2was placed in a grinding device, and deionized water was added to grind for 4h at a rotation speed of 300r·min -1 After grinding, the obtained sample was transferred to an oven at 110°C for drying treatment to remove excess water to obtain a precursor; the molar ratio of Ni(NO3)2, Fe(NO3)2was 1:2, and the mass of water was 1% of the mass of Ni(NO3)2. S12, the precursor is placed in the crucible and transferred to the muffle furnace, heated to 1000℃ at a rate of 3℃·min -1 -1 After the sample is cooled, it is taken out, ground and sieved, and the powder with a particle size below 400 μm is taken, i.e. the oxygen carrier NiFe2O4 is obtained. Oxygen carrier SrFe 12 O 19 The method for preparing the same comprises the following steps: S11, SrCO3, Fe(NO3)2was placed in a grinding device, and deionized water was added, and the grinding was carried out at a rotating speed of 300 r·min -1 for 4 h; after the grinding was completed, the obtained sample was transferred to an oven at 110°C for drying treatment to remove excess water to obtain a precursor; the molar ratio of SrCO3, Fe(NO3)2was 1:12, and the mass of water was 1% of the mass of SrCO3; S12, the precursor is placed in the crucible and transferred to the muffle furnace, heated to 1000°C at a rate of 3°C min -1 and held at this temperature for 10 h; finally, after the sample has cooled, it is removed, ground and sieved, and the powder with a particle size below 400 pm is taken, i.e. the oxygen carrier SrFe 12 O 19 ; The 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 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, N2 in the inner barrel are discharged by passing N2 into the reaction gas inlet pipe, wherein the flow rate of N2 is 500-100 mL·min -1 .

2. The method of claim 1, wherein the low-temperature thermochemical cycle for hydrogen production from water decomposition is characterized by, ​ 3. The method of claim 1, wherein the low-temperature thermochemical cycle for hydrogen production from water decomposition is characterized by, ​ 4. The method of claim 1, wherein the low-temperature thermochemical cycle for hydrogen production from water decomposition is characterized by, ​ 5. The method of claim 1, wherein the low-temperature thermochemical cycle for water decomposition to produce hydrogen is characterized by, ​ ​ ​

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