A hydrogen production system and low-carbon hydrogen production process

Abstract

The present invention provides a hydrogen production system and a low-carbon hydrogen production process. The hydrogen production system includes an SMR system and a CCUS system. The present invention also provides a low-carbon hydrogen production process that fully couples SMR technology with CCUS technology: CCUS technology is used to capture CO and CO2 generated during the SMR hydrogen production process. The captured CO is returned to the SMR system and converted into CO2, and CO2 is further captured, greatly reducing carbon dioxide emissions during the SMR hydrogen production process. The captured CO2 can react with pure hydrogen produced by the SMR system to convert the unstable energy H2 into stable energy CH3OH, realizing the utilization of CO2 for energy storage. In addition, the captured CO2 can also be sealed or otherwise utilized.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas hydrogen production, and in particular relates to a hydrogen production system and a low-carbon hydrogen production process. Background Art

[0002] Hydrogen energy, as a clean and renewable energy source, has a wide range of sources and various applications. It can be used as a renewable energy storage carrier and can be used to produce important chemical products such as methanol and ammonia, which will help promote energy transformation and achieve carbon neutrality goals as soon as possible.

[0003] Methane, the primary component of natural gas and the compound with the largest atomic mass fraction of hydrogen, is a promising feedstock for hydrogen production. As one of the world's three major fossil energy sources, natural gas is low-cost and the associated technologies are mature. Statistics show that natural gas-based hydrogen production already accounts for two-fifths of global industrial hydrogen production, making it the dominant hydrogen production technology worldwide. Natural gas-based hydrogen production technologies can be categorized into three methods: steam methane reforming (SMR), oxygen-free aromatization, and cracking. Steam methane reforming is the most economical, mature, and widely used natural gas-based hydrogen production process. However, this process generates approximately 80% of the byproduct carbon dioxide (CO2). In terms of carbon emission intensity, producing 1 kg of hydrogen emits approximately 10 kg of CO2. The high carbon emissions from hydrogen production are detrimental to achieving low-carbon environmental goals.

[0004] Carbon Capture Utilization and Storage (CCUS) is a technology that separates carbon dioxide from industrial production, energy utilization or the atmosphere and uses it or injects it into the ground to achieve permanent emission reductions. In the context of carbon peak and carbon neutrality, grasping the research and development and promotion and application of CCUS technology is the only way to accelerate the transformation and upgrading of my country's traditional high-energy-consuming and high-emission industries. CCUS key technologies can be divided into carbon capture, carbon utilization and carbon storage technologies according to the process flow. Among them, carbon capture technology can be divided into pre-combustion capture, post-combustion capture and oxygen-enriched combustion capture according to the different stages of carbon dioxide separation. In addition, carbon utilization technology is mainly used for food-grade utilization, chemical product conversion, oil recovery and production increase, biological breeding, etc.; carbon storage technologies mainly include deep-sea storage, geological storage, biological storage, mineralization storage, etc. Summary of the Invention

[0005] In response to the problem of high carbon emissions from existing methane steam reforming hydrogen production processes, the purpose of the present invention is to provide a hydrogen production system and a low-carbon hydrogen production process, coupling steam methane reforming (SMR) with carbon dioxide capture, utilization and storage (CCUS), reducing carbon emissions during the hydrogen production process, utilizing and storing the captured carbon dioxide, and achieving low-carbon hydrogen production.

[0006] A first aspect of the present invention provides a hydrogen production system comprising an SMR system and a CCUS system;

[0007] The SMR system includes a desulfurization device, a pre-reforming device, a reforming device, a first CO conversion device, a second CO conversion device, an H2 purification device and an H2 storage device connected to the H2 purification device in sequence along the hydrogen production route;

[0008] The CCUS system includes, in sequence along the hydrogen production route, a post-combustion capture device, a first CO capture device, a second CO capture device, a first pre-combustion capture device, a second pre-combustion capture device, a CO storage device, a CO2 storage device, and an energy storage and utilization device; the CO storage device is connected to the first CO capture device and the second CO capture device; the CO2 storage device is connected to the post-combustion capture device, the first pre-combustion capture device, and the second pre-combustion capture device.

[0009] In one embodiment of the present invention, the SMR system and the CCUS system are coupled to each other;

[0010] Preferably, the post-combustion capture device and the first CO capture device are connected between the pre-reforming device and the reforming device to achieve a first coupling; and / or

[0011] The second CO capture device is connected between the reforming device and the first CO conversion device to achieve a second coupling; and / or

[0012] The first pre-combustion capture device is connected between the first CO conversion device and the H2 purification device to achieve a third coupling; and / or

[0013] The second pre-combustion capture device is connected between the second CO conversion device and the H2 purification device to achieve a fourth coupling; and / or

[0014] The energy storage and utilization device is connected between the CO2 storage device and the H2 storage device to achieve the fifth coupling.

[0015] The coupling referred to in the present invention refers to the interconnection of various devices in the SMR system and the CCUS system.

[0016] In one embodiment of the present invention, the post-combustion capture device performs post-combustion capture on the CO2 generated by the pre-reforming device, and the first CO capture device captures the CO generated by the pre-reforming device, thereby achieving the first coupling.

[0017] In one embodiment of the present invention, the second CO capture device captures the CO generated by the reforming device to achieve the second coupling.

[0018] In one embodiment of the present invention, the first pre-combustion capture device captures CO2 generated by the first CO conversion device before combustion to achieve the third coupling.

[0019] In one embodiment of the present invention, the second pre-combustion capture device captures CO2 generated by the second CO conversion device before combustion, thereby achieving the fourth coupling.

[0020] In one embodiment of the present invention, the energy storage and utilization device converts the H2 in the H2 storage device into CH3OH through the CO2 in the CO2 storage device, thereby achieving the fifth coupling.

[0021] In one embodiment of the present invention, a first heat exchanger is connected between the second CO capture device and the first CO shift device to control the gas temperature to approach the temperature required for the CO shift reaction; and / or

[0022] A second heat exchanger is connected between the first CO2 shifting device and the first pre-combustion capture device to control the gas temperature to facilitate pre-combustion capture; and / or

[0023] A third heat exchanger is connected between the second CO2 shifting device and the second pre-combustion capture device to control the gas temperature to facilitate pre-combustion capture; and / or

[0024] The SMR system also includes a by-product gas storage device connected to the H2 purification device, which is used to store the by-product gas generated during the H2 purification process.

[0025] In one embodiment of the present invention, in the SMR system, the desulfurization device is a desulfurization tower; the pre-conditioning device is a converter; the reforming device, the first CO conversion device and the second CO conversion device are independently reactors; the H2 purification device is a pressure swing adsorption H2 purification device; and the H2 storage device is an H2 storage tank.

[0026] In one embodiment of the present invention, in the CCUS system, the post-combustion capture device, the first pre-combustion capture device, and the second pre-combustion capture device are independently CO2 adsorption tanks; the first CO capture device and the second CO capture device are independently CO adsorption tanks; the CO2 storage device is a CO2 storage tank; the CO storage device is a CO storage tank; and the energy storage and utilization device is a reactor;

[0027] Preferably, the post-combustion capture device is an adsorption tank filled with alcoholamine;

[0028] The first pre-combustion capture device and the second pre-combustion capture device are independently adsorption tanks filled with alcoholamine;

[0029] The first CO capture device and the second CO capture device are independently adsorption tanks filled with active sodium silicate and active calcium silicate.

[0030] In the hydrogen production system provided by the present invention, taking into account the large production scale in the actual hydrogen production process, the post-combustion capture device, the first pre-combustion capture device, the second pre-combustion capture device, the first CO capture device, and the second CO capture device are not limited to one CO2 adsorption tank or CO adsorption tank; the CO2 storage device, the CO storage device, and the H2 storage device are not limited to one CO2 storage tank, CO storage tank, or H2 storage tank; the post-combustion capture device, the first pre-combustion capture device, and the second pre-combustion capture device are respectively two or more CO2 adsorption tanks connected in parallel; the first CO capture device and the second CO capture device are respectively two or more parallel The CO2 storage device, the CO storage device and the H2 storage device are respectively two or more CO2 storage tanks in parallel, two or more CO storage tanks in parallel or two or more H2 storage tanks in parallel; when the CO2 adsorption tank or the CO adsorption tank is saturated with adsorption, it is switched to other parallel CO2 adsorption tanks and CO adsorption tanks through a valve to continue CO2 adsorption and CO adsorption, and the saturated CO2 adsorption tank and CO adsorption tank are regularly desorbed with CO2 and CO; when the gas storage capacity of the CO2 storage tank, CO storage tank or H2 storage tank reaches the upper limit, it is switched to the parallel CO2 storage tank, CO storage tank or H2 storage tank through a valve for storage.

[0031] A second aspect of the present invention provides a low-carbon hydrogen production process, which comprises the following steps:

[0032] 1) desulfurizing natural gas in a desulfurization device of the hydrogen production system according to the first aspect of the present invention to obtain desulfurized natural gas;

[0033] 2) subjecting the desulfurized natural gas, water vapor, and oxygen-enriched air to a first reaction in the pre-reforming unit to obtain a first mixed gas containing CO, CO2, H2, H2O, and natural gas;

[0034] 3) passing the first mixed gas through the post-combustion capture device and the first CO capture device in sequence to perform CO2 post-combustion capture and CO capture in sequence, thereby obtaining a second mixed gas containing CO, H2, H2O, and natural gas, and the captured CO2 and CO are sequentially stored in the CO2 storage device and the CO storage device;

[0035] 4) allowing the water vapor, oxygen-enriched air, and the second mixed gas to undergo a second reaction in the reformer to obtain a third mixed gas containing CO, CO2, H2, and H2O;

[0036] 5) passing the third mixed gas into the second CO capture device to capture CO to obtain a fourth mixed gas containing CO, CO2, H2 and H2O, and the captured CO is stored in the CO storage device;

[0037] 6) passing the water vapor and the fourth mixed gas into the first CO shift conversion device for a third reaction to obtain a fifth mixed gas containing CO2, H2, and H2O;

[0038] 7) passing the fifth mixed gas into the first pre-combustion capture device to capture CO2 before combustion to obtain a sixth mixed gas containing H2 and H2O, and the captured CO2 is stored in the CO2 storage device;

[0039] 8) introducing water vapor and CO in the CO storage device into the second CO conversion device to perform a fourth reaction to obtain a seventh mixed gas containing CO2, H2, and H2O;

[0040] 9) passing the seventh mixed gas into the second pre-combustion capture device to capture CO2 before combustion to obtain an eighth mixed gas containing H2 and H2O, and the captured CO2 is stored in the CO2 storage device;

[0041] 10) passing the sixth mixed gas and the eighth mixed gas into the H2 purification device for H2 purification, and the obtained pure hydrogen is stored in the H2 storage device;

[0042] 11) The CO2 in the CO2 storage device and the pure hydrogen in the H2 storage device are introduced into the energy storage and utilization device to perform the fifth reaction, and the obtained CH3OH is stored in the CH3OH storage device.

[0043] In one embodiment of the present invention, in step 2), the volume ratio of the desulfurized natural gas, water vapor and oxygen-enriched air is (6 to 6.5): (1 to 1.2): (3.5 to 3.8); and / or

[0044] In step 4), the volume ratio of the second mixed gas, water vapor and oxygen-enriched air is (10 to 10.5): (1 to 1.2): (3.3 to 3.6); and / or

[0045] In step 6), the volume ratio of the fourth mixed gas to the water vapor is (1 to 1.2): (1 to 1.2); and / or

[0046] In step 8), the volume ratio of the water vapor to the CO is (1 to 1.2): (1 to 1.2); and / or

[0047] In step 11), the volume ratio of CO2 to pure hydrogen is (1 to 1.2): (3 to 3.2);

[0048] Preferably, the temperature of the first reaction is 750 to 850K; and / or

[0049] The temperature of the second reaction is 1000K to 1200K; and / or

[0050] The temperature of the third reaction and the fourth reaction is independently not less than 480° C.; and / or

[0051] The temperature of the fifth reaction is 210 to 230° C.; and / or the pressure is 25 to 35 MPa;

[0052] Preferably, the first reaction is carried out under the catalysis of a first catalyst; and / or

[0053] The second reaction is carried out under the catalysis of a second catalyst; and / or

[0054] The third reaction and the fourth reaction are independently carried out under the catalysis of a third catalyst; and / or

[0055] The fifth reaction is carried out under the catalysis of a fourth catalyst;

[0056] Preferably, the oxygen-enriched air is oxygen-doped air with an oxygen volume concentration of not less than 30%; and / or

[0057] The first catalyst, the second catalyst and the third catalyst are independently nickel catalysts; and / or

[0058] The fourth catalyst is a copper-based catalyst.

[0059] In the present invention, the reaction time of various reactions varies with factors such as the material processing volume during actual production, so the specific reaction time of various reactions is not limited.

[0060] In one embodiment of the present invention, the CO2 in the CO2 storage device is sealed;

[0061] Preferably, the storage is geological storage.

[0062] The geological storage referred to in the present invention is to store the captured carbon dioxide in underground geological forms, including salt caverns, oil fields and coal seams.

[0063] In one embodiment of the present invention, the CO2 in the CO2 storage device is subjected to at least one of chemical utilization, mineral utilization, biological utilization and industrial utilization.

[0064] The chemical utilization referred to in the present invention is the chemical use of CO2, especially the utilization of CO2 in oil recovery.

[0065] The mineralization utilization referred to in the present invention is the mineralization use of CO2, especially the utilization of CO2 in converting it into energy.

[0066] The biological utilization referred to in the present invention is to design and construct a new artificial photosynthetic system and pathway by simulating the natural photosynthesis process of plants and microorganisms in nature, so as to more efficiently convert CO2 into synthetic chemicals and agricultural products, especially the role of CO2 in the synthesis of substances such as food and biofertilizer.

[0067] The industrial utilization referred to in the present invention is the industrial use of CO2, especially the utilization of CO2 in fire fighting and industrial raw materials.

[0068] Beneficial effects of the present invention: In response to the problem of high carbon emissions in the existing methane steam reforming hydrogen production process, the present invention provides a hydrogen production system and a low-carbon hydrogen production process. The hydrogen production system includes an SMR system and a CCUS system. The SMR system includes a desulfurization device, a pre-reforming device, a reforming device, a first CO conversion device, a second CO conversion device, an H2 purification device, and an H2 storage device in sequence along the hydrogen production route; the CCUS system includes a post-combustion capture device, a first CO capture device, a second CO capture device, a first pre-combustion capture device, a second pre-combustion capture device, a CO storage device, a CO2 storage device, and an energy storage and utilization device in sequence along the hydrogen production route; the CO storage device is connected to the first CO capture device and the second CO capture device; the CO2 storage device is connected to the post-combustion capture device, the first pre-combustion capture device, and the second pre-combustion capture device. Relying on the hydrogen production system provided by the present invention, the present invention also provides a low-carbon hydrogen production process, which fully couples the SMR technology and CCUS technology: CCUS technology is used to capture CO and CO2 generated in the hydrogen production process of the SMR technology. After the captured CO is returned to the SMR system and converted into CO2, CO2 is further captured, which greatly reduces the carbon dioxide emissions in the SMR hydrogen production process; the captured CO2 can react with the pure hydrogen prepared by the SMR system to convert the unstable energy H2 into stable energy CH3OH, thereby realizing the utilization of CO2 in energy storage. In addition, the captured CO2 can also be sealed or used in other types of ways, such as geological storage, chemical utilization, mineralization utilization, biological utilization and industrial utilization.

[0069] The simulation experiment of the low-carbon hydrogen production process was carried out indoors, and the experimental results showed that:

[0070] (1) In terms of cost: Relying on the hydrogen production system provided by the present invention and adopting the low-carbon hydrogen production process provided by the present invention, the cost of producing hydrogen from natural gas is about 16.8 yuan / kg, which is reduced to 84% of the cost of hydrogen production by the traditional SMR process, significantly reducing the cost of hydrogen production from natural gas;

[0071] (2) In terms of carbon emission intensity: Relying on the hydrogen production system provided by the present invention and adopting the low-carbon hydrogen production process provided by the present invention, the carbon emission intensity of hydrogen produced by natural gas is 1 kg of carbon dioxide emitted for every 1 kg of hydrogen produced. The carbon emission intensity is reduced to less than 1 / 10 of the carbon emission intensity of hydrogen produced by the traditional SMR process, which greatly reduces the carbon emissions of hydrogen produced by natural gas and realizes low-carbon hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a device diagram of the hydrogen production system provided by the present invention.

[0073] Figure 2This is a schematic diagram of the low-carbon hydrogen production process provided by the present invention. DETAILED DESCRIPTION

[0074] The present invention will be further described below with reference to examples. However, the examples are merely illustrative and do not limit the present invention in any way.

[0075] Relying on the hydrogen production system provided by the present invention, combined with Figure 1 、 Figure 2 The low-carbon hydrogen production process provided by the present invention is described in detail.

[0076] In the actual production process, natural gas is introduced into the hydrogen production system along the transmission pipeline at a fixed flow rate to prepare hydrogen. The processing process in the hydrogen production system is as follows.

[0077] Step 1: First, the natural gas is passed through a desulfurization tower to remove sulfides (such as hydrogen sulfide, mercaptans, sulfides, disulfides, and carbon oxysulfide) from the natural gas, thereby obtaining cleaner desulfurized natural gas. This reduces the corrosion of sulfides on equipment during the hydrogen production process, reduces impurities in the natural gas used as the hydrogen production raw material, and reduces the pressure of subsequent H2 purification.

[0078] Step 2: The desulfurized natural gas, water vapor, and oxygen-enriched air (with an oxygen volume concentration of not less than 30%) are introduced into a reformer (e.g., a top burner furnace or a sidewall burner furnace) equipped with a nickel-containing catalyst and set at a temperature of 750 to 850 K (e.g., 750 K, 800 K, 850 K) in a volume ratio of (6 to 6.5):(1 to 1.2):(3.5 to 3.8) for pre-reforming to produce H2, CO2, and CO. Due to the temperature setting, some methane gas has not yet reacted and water vapor will also be slightly excessive, so the first mixed gas containing H2, CO2, CO, H2O, and natural gas is finally discharged from the reformer.

[0079] Step 3: The first mixed gas then flows sequentially through a CO2 adsorption tank (i.e., a post-combustion capture device) filled with a CO2 adsorption material (e.g., an alcohol amine) and a CO adsorption tank (i.e., a first CO capture device) filled with an adsorption material (activated sodium silicate and activated calcium silicate). The CO2 adsorption tank captures CO2 in the first mixed gas by adsorption after combustion, and the CO adsorption tank captures CO in the first mixed gas by adsorption. The CO2 adsorption tank and the CO adsorption tank are then desorbed, and the captured CO2 and CO are discharged into a CO2 storage tank and a CO storage tank for storage, respectively. H2, H2O, and natural gas in the first mixed gas are not adsorbed and flow out of the CO adsorption tank. Moreover, since the adsorption efficiency of CO and CO2 cannot reach 100%, a very small amount of CO2 and a small amount of CO still flow out of the CO adsorption tank. Thus, what flows out of the CO adsorption tank is a second mixed gas containing CO, H2, H2O, natural gas, and a very small amount of CO2.

[0080] Step 4: The second mixed gas flowing out of the CO adsorption tank, water vapor, and oxygen-enriched air (wherein the oxygen volume concentration is not less than 30%) are directly fed into a reforming reactor having a temperature set at 1000 to 1200 K (e.g., 1000 K, 1050 K, 1100 K, 1150 K, 1200 K) and equipped with a nickel catalyst in a volume ratio of (10 to 10.5):(1 to 1.2):(3.3 to 3.6) for reforming to produce H2, CO2, and CO. Since water vapor is slightly excessive and the natural gas cannot be fully reformed, the third mixed gas ultimately discharged from the reforming reactor is mainly composed of H2, CO2, CO, and H2O, and also contains a very small amount of natural gas.

[0081] Step 5: The third mixed gas flows through the CO adsorption tank, which captures the CO therein by adsorption. The CO adsorption tank is desorbed, and the captured CO enters the CO storage tank for storage. Components other than CO in the third mixed gas are not adsorbed by the CO adsorption tank and flow out of the CO adsorption tank. However, since the adsorption efficiency of CO cannot reach 100%, a small amount of CO still flows out of the CO adsorption tank. Therefore, the fourth mixed gas that finally flows out of the CO adsorption tank is mainly composed of H2, CO2, CO, and H2O, and also contains a very small amount of natural gas.

[0082] The purpose of performing CO capture before and after the reforming reactor in steps 4 and 5 respectively is to make the CO conversion more thorough and reduce the pressure of subsequent CO2 capture.

[0083] Step 6: The fourth mixed gas flowing out of the CO adsorption tank flows through the first heat exchanger for heat exchange so that the temperature of the fourth mixed gas is close to the temperature required for the CO shift reaction, and then enters a CO shift reactor (i.e., the first CO shift device) with a temperature set to not less than 480°C (e.g., 480°C, 500°C) and equipped with a nickel catalyst, where a CO shift reaction is carried out to produce CO2 and H2. During this process, a very small amount of natural gas contained in the fourth mixed gas will also react with the water vapor to produce a very small amount of H2 and CO. The content of natural gas after the reaction is very small and can be ignored; thus, a fifth mixed gas having H2, CO2, and H2O as main components and also containing a very small amount of CO is obtained.

[0084] Step 7: The fifth mixed gas flows through the second heat exchanger for heat exchange for pre-combustion capture, and then enters the first pre-combustion capture device (i.e., the CO2 adsorption tank) for CO2 pre-combustion capture. The first pre-combustion capture device is desorbed for CO2, and the CO2 is discharged into the CO2 storage tank for storage. The sixth mixed gas flowing out of the first pre-combustion capture device, which contains H2O and H2 as main components and also contains very small amounts of CO and CO2, enters the H2 purification device for H2 purification.

[0085] Step 8: The CO and water vapor stored in the CO storage tank (the volume ratio of CO to water vapor is (1 to 1.2): (1 to 1.2) are introduced into a CO conversion reactor (i.e., a second CO conversion device) having a temperature set to not less than 480°C (e.g., 480°C, 500°C) and equipped with a nickel catalyst to carry out a CO conversion reaction to produce CO2 and H2. Affected by the CO conversion efficiency and a slight excess of water vapor, a seventh mixed gas having H2, CO2, and H2O as main components and also containing a very small amount of CO is obtained.

[0086] Step 9: The seventh mixed gas flows through the third heat exchanger for heat exchange for pre-combustion capture, and then enters the second pre-combustion capture device (i.e., the CO2 adsorption tank) for CO2 pre-combustion capture. The second pre-combustion capture device is subjected to CO2 desorption, and the CO2 is discharged into the CO2 storage tank for storage. The eighth mixed gas flowing out of the second pre-combustion capture device, which contains H2O and H2 as main components and also contains very small amounts of CO and CO2, enters the H2 purification device for H2 purification.

[0087] Step 10: The H2 purification device purifies the H2 in the sixth mixed gas and the eighth mixed gas, and the purified pure hydrogen (purity not less than 98%) is discharged into the H2 storage tank for storage, and the remaining by-product gas is discharged into the by-product gas storage device for storage.

[0088] Step 11: Discharge part of the CO2 in the CO2 storage tank and the H2 in the H2 storage tank (the volume ratio of CO2 to H2 is (1 to 1.2): (3 to 3.2) into the energy storage and utilization device (i.e., a methanol reactor), and react at 210 to 230°C (e.g., 210°C, 220°C, 230°C), 25 to 30 MPa, and a copper-based catalyst to produce CH3OH, thereby converting the unstable energy H2 into stable energy CH3OH; preferably, the remaining CO2 in the CO2 storage tank is geologically sealed or utilized in other ways (e.g., chemical utilization, mineralization utilization, biological utilization, and industrial utilization).

[0089] Example: In order to illustrate the advantages of using the hydrogen production system provided by the present invention and the low-carbon hydrogen production process provided by the present invention to produce hydrogen from natural gas in reducing hydrogen production costs and carbon emission intensity, the following indoor simulation experiment is provided.

[0090] ⅰDescription of hydrogen production system.

[0091] The capacity of various reactors in the hydrogen production system was reduced to laboratory level. Due to the needs of indoor experiments, natural gas storage devices, water vapor storage devices, and oxygen-enriched air storage devices were added to the SMR system. Considering the purpose of the experiment, the energy storage and utilization devices and CH3OH storage devices in the CCUS system were simplified, as shown in Table 1.

[0092] Table 1. Laboratory-scale hydrogen production system.

[0093]

[0094] ⅱ Laboratory low-carbon hydrogen production.

[0095] It should be noted that, in this embodiment, the pressure in the CO storage device, the CO2 storage device, and the H2 storage device is 15 to 20 MPa; the transfer of gas between different devices during the hydrogen production process is achieved by a gas booster pump.

[0096] 1) First, the natural gas in the natural gas storage tank is discharged into the desulfurization tower to desulfurize the natural gas and remove sulfides (such as hydrogen sulfide, mercaptans, sulfides, disulfides and carbon oxysulfide, etc.) in the natural gas to obtain cleaner desulfurized natural gas.

[0097] 2) The desulfurized natural gas, water vapor in the water vapor storage tank, and oxygen-enriched air (with an oxygen volume concentration of 30%) in the oxygen-enriched air storage tank are introduced into a pre-reforming reactor equipped with a nickel-containing catalyst at a set temperature of 800K in a volume ratio of (6 to 6.5):(1 to 1.2):(3.5 to 3.8) for pre-reforming to produce H2, CO2, and CO. Due to the temperature setting, some methane gas has not yet reacted and water vapor will also be slightly excessive, so what is finally discharged from the reformer is a first mixed gas containing H2, CO2, CO, H2O and natural gas.

[0098] 3) The first mixed gas then flows sequentially through a CO2 adsorption tank (i.e., a post-combustion capture device) filled with a CO2 adsorption material (i.e., an amine) and a CO adsorption tank (i.e., a first CO capture device) filled with an adsorption material (i.e., activated sodium silicate and activated calcium silicate in a mass ratio of 1:1). The CO2 adsorption tank captures CO2 in the first mixed gas by adsorption, and the CO adsorption tank captures CO in the first mixed gas by adsorption. The CO2 adsorption tank and the CO adsorption tank are then respectively desorbed, and the captured CO2 and CO are discharged into a CO2 storage tank and a CO storage tank for storage, respectively. H2, H2O, and natural gas in the first mixed gas are not adsorbed and flow out of the CO adsorption tank. The efficiency of post-combustion capture is 95%, and the efficiency of CO capture is 90%. What flows out of the CO adsorption tank is a second mixed gas containing CO, H2, H2O, natural gas, and a very small amount of CO2.

[0099] 4) The second mixed gas, water vapor in the water vapor storage tank, and oxygen-enriched air in the oxygen-enriched air storage tank (with an oxygen volume concentration of 30%) enter a reforming reactor set at a temperature of 1200K and equipped with a nickel catalyst in a volume ratio of (10 to 10.5):(1 to 1.2):(3.3 to 3.6) for reforming to produce H2, CO2, and CO. At this point, based on the initial 40L of natural gas, the reforming conversion efficiency of the natural gas is 98%. Due to a slight excess of water vapor, the third mixed gas finally discharged from the reforming reactor is composed of approximately 70% H2, approximately 24% CO, approximately 6% CO2, and the remainder natural gas and H2O.

[0100] 5) The third mixed gas flows through a CO adsorption tank (i.e., a second CO capture device), which captures the CO therein by adsorption at a capture efficiency of 90%. The CO adsorption tank is desorbed, and the captured CO enters a CO storage tank for storage. The remaining CO and other components in the third mixed gas are not adsorbed by the CO adsorption tank and flow out of the CO adsorption tank, forming a fourth mixed gas composed primarily of H2, CO2, CO, and H2O, and also containing a very small amount of natural gas.

[0101] 6) The fourth mixed gas flowing out of the CO adsorption tank flows through the first heat exchanger for heat exchange, and then enters a CO shift reactor (i.e., the first CO shift device) with the water vapor in the water vapor storage tank at a volume ratio of (1 to 1.2):(1 to 1.2) set at a temperature of 480°C and equipped with a nickel catalyst to undergo a CO shift reaction, producing CO2 and H2 with a reaction efficiency of 99%. During this process, a very small amount of natural gas contained in the fourth mixed gas also reacts with the water vapor to produce a very small amount of H2 and CO. The content of natural gas after the reaction is very small and can be ignored. A fifth mixed gas is obtained, which is mainly composed of H2, CO2 and H2O, and also contains a very small amount of CO.

[0102] 7) After passing the fifth mixed gas through the second heat exchanger for heat exchange, it is passed into the first pre-combustion capture device (i.e., CO2 adsorption tank) for pre-combustion CO2 capture with a capture efficiency of 97%, thereby obtaining a sixth mixed gas mainly composed of H2 and H2O, and also containing very small amounts of CO and CO2. The first pre-combustion capture device is subjected to CO2 desorption, and the captured CO2 is stored in the CO storage tank.

[0103] 8) The CO stored in the CO storage tank and the water vapor in the water vapor storage tank are introduced into a CO shift reactor (i.e., a second CO shift device) having a temperature set at 480° C. and equipped with a nickel catalyst in a volume ratio of (1 to 1.2):(1 to 1.2) to carry out a CO shift reaction to produce H2 and CO2 with a reaction efficiency of nearly 99%, thereby obtaining a seventh mixed gas having H2, CO2, and H2O as main components and also containing a very small amount of CO.

[0104] 9) The seventh mixed gas is passed through the third heat exchanger for heat exchange, and then passed into the second pre-combustion capture device (i.e., a CO2 adsorption tank) for pre-combustion capture of CO2 with a capture efficiency of 95%. The second pre-combustion capture device is subjected to CO2 desorption, and the CO2 is discharged into a CO2 storage tank for storage; what flows out of the second pre-combustion capture device is an eighth mixed gas composed mainly of H2O and H2, and also containing very small amounts of CO and CO2.

[0105] 10) The sixth mixed gas and the eighth mixed gas are discharged into the H2 purification device for purification to obtain 135L of pure hydrogen (purity of 98%), which is discharged into the H2 storage tank for storage, and the remaining by-product gas is discharged into the by-product gas storage device for storage.

[0106] ⅲEvaluation of indoor simulation experiment results.

[0107] 1. Cost:

[0108] According to the inventor's research, the cost of producing hydrogen from natural gas using the traditional SMR process is about 20 yuan / kg H2; in comparison, relying on the hydrogen production device provided by the present invention and adopting the low-carbon hydrogen production process provided by the present invention to produce hydrogen from natural gas, although the introduction of CCUS equipment will increase the initial investment and operating costs, specifically the capital expenditure and fuel costs will increase by 5%, and the direct operating costs will increase by 130%; but since the captured CO2 can be used together with H2 to produce CH3OH, CO2 can also be used in other fields such as chemistry, biology, and industry. This part of the income can compensate for approximately 26% of the initial cost. Therefore, relying on the hydrogen production device provided by the present invention and adopting the low-carbon hydrogen production process provided by the present invention to produce hydrogen from natural gas, the cost is about 16.8 yuan / kg, which is reduced to 84% of the cost of producing hydrogen from natural gas using the traditional SMR process.

[0109] 2. Carbon emission intensity:

[0110] The inventors have learned through research that the carbon emission intensity of natural gas hydrogen production using the traditional SMR process is about 10 kg of carbon dioxide emitted for every kg of hydrogen produced. However, according to the results of the indoor simulation experiment, it is calculated that the carbon emission intensity of natural gas hydrogen production using the hydrogen production device provided by the present invention and the low-carbon hydrogen production process provided by the present invention is less than 1 kg of carbon dioxide emitted for every kg of hydrogen produced, which is at least reduced to less than 1 / 10 of the carbon emission intensity of natural gas hydrogen production using the traditional SMR process. The carbon emission intensity is greatly reduced, thereby achieving low-carbon hydrogen production.

[0111] Although the present invention has been described with reference to specific embodiments, those skilled in the art will appreciate that various modifications may be made without departing from the true spirit and scope of the invention. Furthermore, the subject matter, spirit, and scope of the invention may be modified in various ways to adapt to specific circumstances, materials, combinations of materials, and methods. All such modifications are intended to be within the scope of the claims.

Claims

1. A hydrogen production system comprising an SMR system and a CCUS system; The SMR system includes a desulfurization device, a pre-reforming device, a reforming device, a first CO conversion device, a second CO conversion device, an H2 purification device and an H2 storage device connected to the H2 purification device in sequence along the hydrogen production route; The CCUS system includes, in sequence along the hydrogen production route, a post-combustion capture device, a first CO capture device, a second CO capture device, a first pre-combustion capture device, a second pre-combustion capture device, a CO storage device, a CO2 storage device, and an energy storage and utilization device; the CO storage device is connected to the first CO capture device and the second CO capture device; the CO2 storage device is connected to the post-combustion capture device, the first pre-combustion capture device, and the second pre-combustion capture device; The SMR system and the CCUS system are coupled to each other; The post-combustion capture device and the first CO capture device are connected between the pre-reforming device and the reforming device, the post-combustion capture device performs post-combustion capture on the CO2 generated by the pre-reforming device, and the first CO capture device captures the CO generated by the pre-reforming device, thereby achieving the first coupling; The second CO capture device is connected between the reformer and the first CO conversion device, and the second CO capture device captures the CO generated by the reformer to achieve a second coupling; The first pre-combustion capture device is connected between the first CO conversion device and the H2 purification device, and the first pre-combustion capture device captures the CO2 generated by the first CO conversion device before combustion, thereby achieving a third coupling; The second pre-combustion capture device is connected between the second CO conversion device and the H2 purification device, and the second pre-combustion capture device captures the CO2 generated by the second CO conversion device before combustion, thereby achieving the fourth coupling; The energy storage and utilization device is connected between the CO2 storage device and the H2 storage device. The energy storage and utilization device converts the H2 in the H2 storage device into CH3OH through the CO2 in the CO2 storage device, thereby achieving the fifth coupling.

2. A low-carbon hydrogen production process comprising the following steps: 1) desulfurizing natural gas in the desulfurization device of the hydrogen production system according to claim 1 to obtain desulfurized natural gas; 2) subjecting the desulfurized natural gas, water vapor, and oxygen-enriched air to a first reaction in the pre-reforming unit to obtain a first mixed gas containing CO, CO2, H2, H2O, and natural gas; 3) passing the first mixed gas through the post-combustion capture device and the first CO capture device in sequence to perform CO2 post-combustion capture and CO capture in sequence, thereby obtaining a second mixed gas containing CO, H2, H2O, and natural gas, and the captured CO2 and CO are sequentially stored in the CO2 storage device and the CO storage device; 4) allowing the water vapor, oxygen-enriched air, and the second mixed gas to undergo a second reaction in the reformer to obtain a third mixed gas containing CO, CO2, H2, and H2O; 5) passing the third mixed gas into the second CO capture device to capture CO to obtain a fourth mixed gas containing CO, CO2, H2 and H2O, and the captured CO is stored in the CO storage device; 6) passing the water vapor and the fourth mixed gas into the first CO shift conversion device for a third reaction to obtain a fifth mixed gas containing CO2, H2, and H2O; 7) passing the fifth mixed gas into the first pre-combustion capture device to capture CO2 before combustion to obtain a sixth mixed gas containing H2 and H2O, and the captured CO2 is stored in the CO2 storage device; 8) introducing water vapor and CO in the CO storage device into the second CO conversion device to perform a fourth reaction to obtain a seventh mixed gas containing CO2, H2, and H2O; 9) passing the seventh mixed gas into the second pre-combustion capture device to capture CO2 before combustion to obtain an eighth mixed gas containing H2 and H2O, and the captured CO2 is stored in the CO2 storage device; 10) passing the sixth mixed gas and the eighth mixed gas into the H2 purification device for H2 purification, and the obtained pure hydrogen is stored in the H2 storage device; 11) The CO2 in the CO2 storage device and the pure hydrogen in the H2 storage device are introduced into the energy storage and utilization device to perform the fifth reaction, and the obtained CH3OH is stored in the CH3OH storage device.

3. The low-carbon hydrogen production process according to claim 2, characterized in that: In step 2), the volume ratio of the desulfurized natural gas, water vapor and oxygen-enriched air is (6 to 6.5): (1 to 1.2): (3.5 to 3.8); and / or In step 4), the volume ratio of the second mixed gas, water vapor and oxygen-enriched air is (10 to 10.5): (1 to 1.2): (3.3 to 3.6); and / or In step 6), the volume ratio of the fourth mixed gas to the water vapor is (1 to 1.2): (1 to 1.2); and / or In step 8), the volume ratio of the water vapor to the CO is (1 to 1.2): (1 to 1.2); and / or In step 11), the volume ratio of CO2 to pure hydrogen is (1 to 1.2):(3 to 3.2).

4. The low-carbon hydrogen production process according to claim 2, characterized in that: The temperature of the first reaction is 750 to 850K; and / or The temperature of the second reaction is 1000K to 1200K; and / or The temperature of the third reaction and the fourth reaction is independently not less than 480° C.; and / or The temperature of the fifth reaction is 210 to 230° C.; and / or the pressure is 25 to 35 MPa.

5. The low-carbon hydrogen production process according to any one of claims 2 to 4, characterized in that: The CO2 in the CO2 storage device is sealed.

6. The low-carbon hydrogen production process according to claim 5, characterized in that: The storage mentioned is geological storage.

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