Method and device for producing hydrogen through thermochemical sulfur-iodine circulation and simultaneously mineralizing CO2 and co-producing MgSO4

Abstract

The invention belongs to the field of CO2 emission reduction and thermochemical hydrogen production, and particularly relates to a method and device for producing hydrogen through thermochemical sulfur-iodine circulation and simultaneously mineralizing CO2 and co-producing MgSO4. The method comprises the steps that mixed flue gas obtained after flue gas treatment of a coal-fired power plant serves as a raw material of a Bensen reaction, SO2, I2 and water are subjected to the Bensen reaction, the generated mixed solution reacts with magnesium silicate minerals, and the magnesium silicate minerals are generated; the generated MgI2 and MgSO4 solutions are evaporated, concentrated and crystallized, and then react with CO2 supplemented in the flue gas to generate HI gas, MgCO3 and MgSO4.nH2O crystals; hI is decomposed to generate I2 and hydrogen, then the I2 and the hydrogen are sprayed and washed by a mixed solution generated by the Bunsen reaction, the hydrogen is discharged, and a spraying washing solution is returned for the Bunsen reaction. And dissolving MgCO3 and MgSO4.nH2O crystals, and then filtering and separating the MgCO3 and MgSO4.nH2O crystals. The reaction conditions are mild, CO2 is mineralized and fixed, H2 and MgSO4 are co-produced at the same time, and large-scale industrial application is easy.

Description

Technical Field

[0001] The present application belongs to the field of CO2 emission reduction and thermochemical hydrogen production, and specifically relates to a method and device for thermochemical sulfur-iodine cycle hydrogen production and simultaneous mineralization of CO2 to co-produce MgSO4. Background Art

[0002] At present, CO2 capture and storage (CCS) technology is the main end-of-pipe emission reduction strategy and has been widely studied. However, the existing CCS technology still faces economic problems in its commercial application due to its high cost and energy consumption. In addition, there may be a series of risks in the geological storage of CO2, such as gas leakage, groundwater pollution, and even geological disasters. Carbon dioxide mineralization is a new type of carbon dioxide emission reduction technology that can convert carbon dioxide into stable minerals, thereby realizing the long-term storage and utilization of carbon dioxide. This technology can not only reduce carbon dioxide emissions, but also produce products with certain added value, and is expected to develop into a CO2 control and utilization technology for large-scale application in the future. The raw materials in CO2 mineralization technology are the source of alkaline earth metal cations required for mineralization reactions. The abundance of raw materials fundamentally determines the upper limit of mineralization capacity. Alkaline earth metal minerals in nature, such as serpentine and olivine, which are mainly magnesium silicate ores, have the ability to mineralize 36,000GtCO2. CO2 mineralization must use alkaline earth metal minerals, namely calcium magnesium silicate, as raw materials. On the other hand, the main product of CO2 mineralization technology is calcium magnesium carbonate, which has low economic and added value, which is also an important factor restricting its commercial application. If a CO2 mineralization technology has high added value and economic by-products or can be organically combined with other more economical energy technologies, it will be more dynamic.

[0003] Hydrogen energy is a secondary energy source, also known as zero-pollution high-efficiency energy, which can be produced by a variety of methods. Moreover, during the combustion process, it can be directly converted into electricity and water without emitting any pollutants. Water can produce hydrogen through thermal dissociation, but the reaction requires a high temperature of more than 2500°C. The sulfur-iodine cycle hydrogen production method divides the water decomposition reaction into several steps, which can not only reduce the reaction temperature, but also avoid the hydrogen-oxygen separation problem, and the sulfur dioxide and iodine used in the cycle can be recycled. The sulfur-iodine (SI) cycle was first proposed by the General Atomics Corporation in the United States in the 1970s. Because it has many advantages, including easy continuous operation of the full-phase process, high energy utilization efficiency, completely closed cycle, and can be matched with nuclear energy or solar energy. The sulfur-iodine cycle has the potential for large-scale, low-cost hydrogen production. Thermochemical sulfur-iodine cycles are divided into two categories: closed-loop cycles and open-loop cycles. The main difference is whether H2SO4 needs to be decomposed (decomposition temperature 850-1000°C). For open-loop circulation, H2SO4 no longer decomposes, which reduces the maximum temperature required by the system (450-500°C), but it requires a continuous supply of SO2 to the system.

[0004] The prior art has reported cases of combining the two technologies, such as the Chinese invention patent publication number: CN108715438B, title: Method and device for thermochemical cycle mineralization of CO2 and simultaneous decomposition of H2O to produce H2 and co-produce H2SO4. This invention organically combines CO2 mineralization technology with thermochemical sulfur-iodine open-circuit cycle decomposition of water to produce hydrogen technology, mineralizes and fixes CO2 under relatively mild reaction conditions, and simultaneously co-produces high value-added H2 and H2SO4. The present invention cleverly avoids the HI-I2 distillation separation process in the traditional hydrogen production cycle by organically combining the hydrogen production cycle with the mineralization technology, and the cycle has a higher theoretical thermal efficiency. However, the invention requires the input of excessive iodine, which not only increases the initial investment cost, but also increases the risk of iodine deposition blocking the pipeline. At the same time, the electrodialysis method is used to concentrate hydroiodic acid, and its cost is still relatively high.

[0005] In addition, the prior art has also been reported, for example, China Invention Patent Application Publication No.: CN113562692A, Name: Method for Deep Peak Shaving of Coal-fired Power Plant Coupled with Thermochemical Sulfur-iodine Open-circuit Cycle Hydrogen Production, the application is to couple the coal-fired unit of the coal-fired power plant with the thermochemical sulfur-iodine open-circuit cycle water decomposition hydrogen production system for operation; the coal-fired unit transports the flue gas after denitrification and dust removal to the hydrogen production system, provides SO2 for the Bunsen reaction, and reacts with H2O and I2 to generate H2SO4 phase and HIx phase solutions through the Bunsen reaction; wherein the H2SO4 phase solution is purified and distilled to obtain a concentrated sulfuric acid product; after the HIx phase solution is purified, concentrated and distilled, the obtained HI is decomposed and condensed to obtain hydrogen, and the hydrogen is purified and sent to a high-pressure hydrogen storage tank; in the hydrogen production system, the heat required for H2SO4 distillation and HI decomposition is provided by the excess high-temperature steam during the deep peak-shaving operation of the coal-fired power plant. Although the present application couples the coal-fired unit of a coal-fired power plant with a thermochemical sulfur-iodine open-loop water decomposition hydrogen production system, it does not involve the mineralization of CO2, and there is still room for improvement. Summary of the invention

[0006] In view of the problems existing in the prior art, the present application proposes a method and device for thermochemical sulfur-iodine cycle hydrogen production and simultaneous mineralization of CO2 and co-production of MgSO4. By eliminating the separation step of hydroiodic acid and sulfuric acid, not only the input of iodine and water is reduced, the cost of acid solution concentration and the risk of iodine deposition blocking the pipeline are reduced, and the continuity of system operation is ensured. At the same time, the hydroiodic acid phase does not need to be purified by desulfurization, which is conducive to system simplification. Desulfurization of coal-fired power plants is achieved, H2SO4 no longer needs to be decomposed, the maximum heat source temperature required by the system is greatly reduced, and MgSO4, a chemical raw material with high added value, is obtained. The entire system can fully utilize resources and obtain considerable economic and environmental benefits.

[0007] On the one hand, the present application discloses a method for thermochemical sulfur-iodine cycle hydrogen production and simultaneous mineralization of CO2 to co-produce MgSO4, the method comprising: (S1) the flue gas of a coal-fired power plant is subjected to denitrification and dust removal treatment to obtain a mixed flue gas of SO2, N2 and CO2, the flue gas is used as a gas phase reaction raw material for a Bunsen reaction, and the liquid phase reaction raw material of the Bunsen reaction comes from external supplementary water, SO2 in the mixed flue gas is absorbed and reacted, CO2 and N2 are discharged, I2, SO2, and H2O undergo a Bunsen reaction and generate a mixed liquid, the mixed liquid reacts with a magnesium silicate mineral to generate MgI2, MgSO4 and SiO2, wherein SiO2 is filtered and output as a by-product; (S2) MgI2 and MgSO4 solutions are then concentrated and crystallized to obtain water vapor and MgI2·nH2O crystals and MgSO4·nH2O crystals; (S3) water vapor, MgI2·nH2O crystals and MgSO4·nH2O crystals then react with the CO2 discharged and collected by (S1) to generate HI gas, MgCO3 and MgSO4·nH2O crystals, and HI is discharged in the form of gas; (S4) the HI gas decomposes to produce I2 and hydrogen, and the I2 and hydrogen as well as the unreacted HI gas are spray-washed, the sprayed liquid comes from the mixed liquid generated by the Bunsen reaction in (S1), the hydrogen is discharged after washing as the product output, and the spray-washed liquid is returned to (S1) as the liquid raw material for the Bunsen reaction; (S5) The MgCO3 and MgSO4·nH2O crystals are dissolved in water and then separated by filtration. The collected MgCO3 is output as a by-product, and the MgSO4 solution is dried and output as a product.

[0008] Particularly, the conditions of the (S1) Bunsen reaction are 20-120° C. and 1-2 atm.

[0009] Particularly, the reaction temperature of the mixed solution generated by the (S1) Bunsen reaction and the magnesium silicate mineral is controlled at 20-90°C.

[0010] Particularly, the reaction temperature of (S3) is controlled at 180-250°C.

[0011] In particular, the method for separating the CO2 and N2 discharged from (S1) includes liquefaction fractionation and membrane separation, and the separated and collected CO2 is sent to (S3) to participate in the reaction.

[0012] Particularly, the HI gas in (S4) is decomposed into I2 and H2 at 450-500°C in the presence of a catalyst, and I2 and unreacted HI are spray-washed, and hydrogen is output as a product.

[0013] Particularly, the magnesium silicate mineral is a natural ore.

[0014] Particularly, the natural mineral is serpentine and / or olivine.

[0015] On the other hand, the present application also discloses a device for thermochemical sulfur-iodine cycle hydrogen production and simultaneous mineralization of CO2 and co-production of MgSO4, comprising a Bunsen reactor 1, a salt generation reactor 2, a condenser 3, a distillation device 4, a hydrolysis and carbonation reactor 5, a MgSO4 dissolver 6, an HI decomposer 7, a flue gas treatment device 8, and a CO2 collection device 9; the flue gas treatment device 8, the Bunsen reactor 1, the salt generation reactor 2, the distillation device 4, and the hydrolysis and carbonation reactor 5 are connected in sequence, and the hydrolysis and carbonation reactor 5 is connected to the MgSO4 dissolver 6 and the HI decomposer 7 respectively, and the HI decomposer 7 is connected to the condenser 3 and the Bunsen reactor 1, and the Bunsen reactor 1 is also connected to the CO2 collection device 9 and the hydrolysis and carbonation reactor 5 in sequence; the device is operated according to the above method.

[0016] In particular, the Bunsen reactor 1 includes at least two liquid phase inlets, two liquid phase outlets, and a gas phase inlet, wherein one liquid phase inlet is connected to the condenser 3 for receiving the iodine-containing mixed liquid for spray washing, one liquid phase inlet is used for external water supplementation, and one liquid phase outlet is connected to the condenser 3 for discharging the mixed liquid for spraying; one liquid phase outlet is connected to the salt generation reactor 2 for discharging the mixed liquid of the Bunsen reaction; and one gas phase inlet is used to receive the flue gas treated by the flue gas treatment device 8; The salt generation reactor 2 includes at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet, and one solid phase outlet; the one liquid phase inlet is used to receive the HI and sulfuric acid mixed solution discharged from the Bunsen reactor 1; the one liquid phase outlet is connected to the distillation device 4 to discharge the MgI2 and MgSO4 mixed solution; the one solid phase inlet is used to supplement the magnesium silicate ore; and the one solid phase outlet is used to discharge the by-product SiO2; The distillation device 4 includes at least one liquid phase inlet, one solid phase outlet, and one gas phase outlet; the liquid phase inlet is used to receive the mixed solution of MgI2 and MgSO4, the solid phase outlet is used to discharge MgI2·nH2O crystals and MgSO4·nH2O crystals, and the gas phase outlet is used to discharge water vapor; The hydrolysis carbonation reactor 5 comprises at least one solid phase inlet, one solid phase outlet, two gas phase inlets and one gas phase outlet, wherein the solid phase inlet is used to receive MgI2·nH2O crystals and MgSO4·nH2O crystals, and the solid phase outlet is used to discharge MgCO3 and MgSO4·nH2O crystals; the gas phase inlet is used to receive water vapor from the distillation device 4, the gas phase inlet is used to receive CO2; and the gas phase outlet is used to discharge HI gas; The HI decomposer 7 is connected to the hydrolysis carbonation reactor 5, receives the HI gas and decomposes it; The condenser 3 includes at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet, wherein the liquid phase inlet is connected to the Bunsen reactor 1 for receiving the HI and H2SO4 mixed solution produced by the Bunsen reaction; the liquid phase outlet is connected to the Bunsen reactor 1 for discharging the iodine-containing mixed solution for spray washing; the gas phase inlet is connected to the HI decomposer 7 for receiving HI, I2 and H2; and the gas phase outlet is used to discharge the product hydrogen; The MgSO4 dissolver 6 includes at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet and one solid phase outlet, wherein the liquid phase inlet is used to supplement water from the outside, a liquid phase outlet discharges the MgSO4 solution, a solid phase inlet is connected to the hydrolysis carbonation reactor 5 to receive MgCO3 and MgSO4·nH2O crystals; and a solid phase outlet discharges the byproduct MgCO3 to the outside.

[0017] The above technical scheme has the following advantages or beneficial effects: Bunsen reaction is an exothermic SO2 gas absorption reaction, which spontaneously proceeds in the liquid phase within the range of 20 to 100 ° C to generate mutually soluble HI and H2SO4. Excessive iodine and water must be added to separate the two acids. In CO2 mineralization technology, natural ores are often required to be acid-leached to extract alkaline earth metal cations therein. The present application innovatively combines thermochemical sulfur-iodine cycle hydrogen production with mineralized CO2 co-production of MgSO4. By eliminating the separation step of hydroiodic acid and sulfuric acid, it not only reduces the input of iodine and water, but also reduces the cost of acid solution concentration and the risk of iodine deposition blocking the pipeline, ensuring the continuity of system operation. At the same time, the hydroiodic acid phase does not need to undergo a purification step of desulfurization, which is conducive to system simplification. Desulfurization of coal-fired power plants is achieved, H2SO4 no longer needs to be decomposed, the maximum heat source temperature required by the system is greatly reduced, and a chemical raw material MgSO4 with high added value is obtained. The entire system can fully utilize resources and obtain considerable economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art description. Obviously, for those skilled in the art, other drawings can be obtained based on the provided drawings without creative work.

[0019] Figure 1 It is a schematic diagram of the device for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 to produce MgSO4 according to the present invention.

[0020] Among them, 1-Bunsen reactor, 2-salt generation reactor, 3-condenser, 4-distillation device, 5-hydrolysis carbonation reactor, 6-MgSO4 dissolver, 7-HI decomposer, 8-flue gas treatment device, 9-CO2 collection device. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application and are intended to be used to explain the inventive concept. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0022] Unless otherwise clearly specified and limited, the terms "connection", "communication" and the like used in the description should be understood in a broad sense, for example, it can be fixed connection, detachable connection, or integration; it can be mechanical connection, electrical connection; it can be directly connected, indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments can be understood according to specific circumstances.

[0023] The term "a specific embodiment" used in the description means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0024] like Figure 1 As shown, a device for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and co-producing MgSO4 is proposed in a specific embodiment of the present application. The device mainly includes a Bunsen reactor 1, a salt generation reactor 2, a condenser 3, a distillation device 4, a hydrolysis carbonation reactor 5, a MgSO4 dissolver 6, a HI decomposer 7, a flue gas treatment device 8, and a CO2 collection device 9. The flue gas treatment device 8, the Bunsen reactor 1, the salt generation reactor 2, the distillation device 4, and the hydrolysis carbonation reactor 5 are connected in sequence, and the hydrolysis carbonation reactor 5 is respectively connected to the MgSO4 dissolver 6 and the HI decomposer 7, and the HI decomposer 7 is connected to the condenser 3 and the Bunsen reactor 1, and the Bunsen reactor 1 is also connected to the CO2 collection device 9 and the hydrolysis carbonation reactor 5 in sequence.

[0025] The Bunsen reactor 1 includes at least two liquid phase inlets, two liquid phase outlets, and one gas phase inlet, wherein one liquid phase inlet is connected to the condenser 3 for receiving the iodine-containing mixed liquid for spray washing, one liquid phase inlet is used to supplement water from the outside, and one liquid phase outlet is connected to the condenser 3 for discharging the mixed liquid for spraying; one liquid phase outlet is connected to the salt generation reactor 2 for discharging the mixed liquid of the Bunsen reaction; and one gas phase inlet is used to receive the flue gas treated by the flue gas treatment device 8, wherein the flue gas mainly includes SO2, N2 and CO2.

[0026] The salt generation reactor 2 includes at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet, and one solid phase outlet; the one liquid phase inlet is used to receive the HI and sulfuric acid mixed solution discharged from the Bunsen reactor 1; the one liquid phase outlet is connected to the distillation device 4 to discharge the MgI2 and MgSO4 mixed solution; the one solid phase inlet is used to replenish magnesium silicate ore; and the one solid phase outlet is used to discharge the by-product SiO2.

[0027] The distillation device 4 includes at least one liquid phase inlet, one solid phase outlet, and one gas phase outlet; the liquid phase inlet is used to receive the mixed solution of MgI2 and MgSO4, the solid phase outlet is used to discharge MgI2·nH2O crystals and MgSO4·nH2O crystals, and the gas phase outlet is used to discharge water vapor.

[0028] The hydrolysis carbonation reactor 5 includes at least one solid phase inlet, one solid phase outlet, two gas phase inlets and one gas phase outlet, wherein the solid phase inlet is used to receive MgI2·nH2O crystals and MgSO4·nH2O crystals, and the solid phase outlet is used to discharge MgCO3 and MgSO4·nH2O crystals; the gas phase inlet is used to receive water vapor from the distillation device 4, and the gas phase inlet is used to receive CO2; and the gas phase outlet is used to discharge HI gas.

[0029] The HI decomposer 7 is connected to the hydrolysis and carbonation reactor 5, receives the HI gas and decomposes it.

[0030] The condenser 3 includes at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet, wherein the liquid phase inlet is connected to the Bunsen reactor 1 for receiving the HI and H2SO4 mixed solution produced by the Bunsen reaction; the liquid phase outlet is connected to the Bunsen reactor 1 for discharging the iodine-containing mixed solution for spray washing; the gas phase inlet is connected to the HI decomposer 7 for receiving HI, I2 and H2; and the gas phase outlet is used to discharge the product hydrogen.

[0031] The MgSO4 dissolver 6 includes at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet and one solid phase outlet, wherein the liquid phase inlet is used to supplement water from the outside, a liquid phase outlet discharges the MgSO4 solution, a solid phase inlet is connected to the hydrolysis carbonation reactor 5 to receive MgCO3 and MgSO4·nH2O crystals; and a solid phase outlet discharges the byproduct MgCO3 to the outside.

[0032] A specific embodiment of the present application proposes a method for thermochemical sulfur-iodine cycle hydrogen production and simultaneous mineralization of CO2 and co-production of MgSO4, which includes the following steps. The flue gas of a coal-fired power plant is subjected to denitrification and dust removal treatment by a flue gas treatment device 8. The flue gas after treatment mainly includes SO2, N2 and CO2. The flue gas then enters the Bunsen reactor 1 as a gas-phase reaction raw material for the Bunsen reaction. The liquid-phase reaction raw material in the Bunsen reactor 1 comes from the condenser 3 and external supplementary water. The SO2 in the flue gas is absorbed and reacted, and CO2 and N2 are discharged. In the Bunsen reactor 1, a spontaneous exothermic reaction occurs at 20-120°C and 1-2atm to generate a mixed solution of HI and H2SO4. The chemical reaction is as follows: I2 +SO2 +2H2O =2HI +H2SO4. The HI and H2SO4 mixed solution discharged from the Bunsen reactor 1 enters the salt generation reactor 2, where it undergoes a spontaneous exothermic reaction with the magnesium silicate natural mineral. The reaction temperature is controlled at 20-90°C, and the reaction generates MgSO4, MgI2 and SiO2, of which SiO2 is filtered and output as a by-product.

[0033] MgI2 and MgSO4 solutions enter the distillation device 4 for concentration and crystallization to obtain water vapor and MgI2·nH2O crystals and MgSO4·nH2O crystals. Water vapor, MgI2·nH2O crystals and MgSO4·nH2O crystals are sent to the hydrolysis carbonation reactor 5, and CO2 collected from the flue gas by the CO2 collection device 9 is introduced at the same time. Commonly used CO2 and N2 separation methods include liquefaction fractionation, membrane separation and other technologies, which are not described in detail in this application. The reaction temperature is controlled at 180-250°C, which is higher than the boiling point of HI -35.5°C and lower than the boiling point of H2SO4 338°C. MgI2 can undergo the following reaction: MgI2 +H2O +CO2=MgCO3 +2HI. At 180-250°C, HI continuously leaves in the form of gas, achieving gas-solid separation of the product, and the hydrolysis carbonation reaction of MgI2 can continue to proceed forward until the reactants are exhausted. However, at 180-250°C, H2SO4 cannot leave the reactor in the form of gas, and MgSO4 cannot undergo hydrolysis and carbonation reaction and still exists as MgSO4.

[0034] The HI gas generated by the reaction enters the HI decomposer 7, and the MgCO3 and MgSO4·nH2O crystals enter the MgSO4 dissolver 6. After MgCO3 and unreacted MgSO4 are washed and filtered, MgCO3 is output as a by-product, and the MgSO4 solution is output as a product after drying. The HI gas enters the HI decomposer 7, and the following reaction occurs under the condition of 450-500°C catalyst: 2HI = I2 + H2. I2 and unreacted HI are sprayed and washed away in the condenser 3, and returned to the Bunsen reactor 1 in the form of iodine-containing mixed liquid to enter the next cycle, and hydrogen is output as a product.

[0035] Taking serpentine Mg3Si2O5(OH)4 as an example, the overall reaction of the whole process is: Mg3Si2O5(OH)4 +CO2 +2SO2 =2MgSO4 +MgCO3 +2H2 +2SiO 2。

[0036] The present application uses a thermochemical sulfur-iodine cycle to produce hydrogen while mineralizing CO2 and co-producing MgSO4. By eliminating the separation step of hydroiodic acid and sulfuric acid, not only the input of iodine and water is reduced, the cost of acid solution concentration and the risk of iodine deposition blocking the pipeline are reduced, and the continuity of system operation is ensured. At the same time, the hydroiodic acid phase does not need to undergo a purification step of desulfurization, which is conducive to system simplification. Desulfurization of coal-fired power plants is achieved, H2SO4 no longer needs to be decomposed, the maximum heat source temperature required by the system is greatly reduced, and MgSO4, a chemical raw material with high added value, is obtained. The entire system can achieve full utilization of resources and obtain considerable economic and environmental benefits. Example 1

[0037] 150molH2O, 20molI2 and 20molSO2 are fed into Bunsen reactor 1, and a self-exothermic reaction of I2+SO2+2H2O=2HI+H2SO4 occurs at 80℃ and normal pressure to produce HI (56.5%wt) and H2SO4 (21.6%wt), which react with serpentine in salt generation reactor 2. The temperature is controlled at 60℃. The chemical reactions include: 6HI+Mg3Si2O5(OH)4=3MgI2+5H2O+2SiO2, 3H2SO4+Mg3Si2O5(OH)4=3MgSO4+5H2O+2SiO2. The mixed solution of MgI2, MgSO4, H2O and SiO2 generated by the reaction is filtered and washed to obtain the by-product SiO2. The filtrate is sent to the distillation device 4 for concentration and crystallization to obtain MgI2·nH2O and MgSO4·nH2O crystals, which are sent to the hydrolysis and carbonation reactor 5 to undergo hydrolysis and carbonation reaction with CO2 and water vapor. The reaction temperature is controlled at 200°C to finally obtain HI gas and product MgCO3. The chemical reaction formula of the reaction is: MgI2 +H2O +CO2=MgCO3 +2HI. The generated HI gas is sent to the HI catalytic decomposition reactor to react at 500°C. The generated I2 and HI are washed and removed in the condensation tower. The iodine-containing liquid returns to the Bunsen reactor 1 to enter the next cycle, and hydrogen is output as a product. The mixture of MgSO4·nH2O crystals and MgCO3 solid is filtered and washed in the MgSO4 dissolver 6 to obtain the by-product MgCO3. The MgSO4 is dried and output as a product. Example 2

[0038] 100 mol H2O, 10 mol I2 and 10 mol SO2 are fed into Bunsen reactor 1, and a self-exothermic reaction occurs at 80°C and atmospheric pressure as follows: I2 +SO2 +2H2O =2HI +H2SO4. HI (51.0%wt) and H2SO4 (19.7%wt) are produced and react with olivine in salt generation reactor 2, and the temperature is controlled at 60°C. The chemical reaction is as follows: 4HI +Mg2SiO4 =2MgI2 +2H2O +SiO2, 2H2SO4 +Mg2SiO4 =2MgSO4 +2H2O +SiO2. The mixed solution of MgI2, MgSO4, H2O and SiO2 generated by the reaction is filtered and washed to obtain the by-product SiO2. The filtrate is sent to the distillation device 4 for concentration and crystallization to obtain MgI2·nH2O and MgSO4·nH2O crystals, which are sent to the hydrolysis and carbonation reactor 5 to undergo hydrolysis and carbonation reaction with CO2 and water vapor. The reaction temperature is controlled at 220°C to finally obtain HI gas and product MgCO3. The chemical reaction formula of the reaction is as follows: MgI2 +H2O +CO2=MgCO3 +2HI. The generated HI gas is sent to the HI catalytic decomposition reactor to react at 500°C. The generated I2 and HI are washed and removed in the condensation tower. The iodine-containing liquid returns to the Bunsen reactor 1 to enter the next cycle, and hydrogen is output as a product. The mixture of MgSO4·nH2O crystals and MgCO3 solid is filtered and washed in the MgSO4 dissolver 6 to obtain the by-product MgCO3. The MgSO4 is dried and output as a product.

[0039] Although the embodiments of the present application have been shown and described above, it is to be understood that the above embodiments are exemplary and cannot be construed as limiting the present application. Without departing from the spirit and scope of the present application, the present application may also have various changes and improvements, which all fall within the scope of the present application to be protected.

Claims

1. A method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 to produce MgSO4, characterized in that: The method comprises: (S1) the flue gas of a coal-fired power plant is subjected to denitration and dust removal treatment to obtain a mixed flue gas of SO2, N2 and CO2, the flue gas is used as a gas phase reaction raw material for a Bunsen reaction, the liquid phase reaction raw material of the Bunsen reaction comes from external supplementary water, SO2 in the mixed flue gas is absorbed and reacted, CO2 and N2 are discharged, I2, SO2, and H2O undergo a Bunsen reaction to generate a mixed liquid, the mixed liquid reacts with a magnesium silicate mineral to generate MgI2, MgSO4 and SiO2, wherein SiO2 is filtered and output as a by-product; (S2) MgI2, MgSO4 solution is then concentrated and crystallized to obtain water vapor and MgI2·nH2O crystals and MgSO4·nH2O crystals; (S3) water vapor, MgI2·nH2O crystals and MgSO4·nH2O crystals then react with the CO2 discharged and collected by (S1) to generate HI gas, MgCO3 and MgSO4·nH2O crystals, and HI is discharged in the form of gas; (S4) the HI gas decomposes to produce I2 and hydrogen, and the I2 and hydrogen as well as the unreacted HI gas are spray-washed, the sprayed liquid comes from the mixed liquid generated by the Bunsen reaction in (S1), the hydrogen is discharged after washing as the product output, and the spray-washed liquid is returned to (S1) as the liquid raw material for the Bunsen reaction; (S5) The MgCO3 and MgSO4·nH2O crystals are dissolved in water and then separated by filtration. The collected MgCO3 is output as a by-product, and the MgSO4 solution is dried and output as a product.

2. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The conditions of the (S1) Bunsen reaction are 20-120° C. and 1-2 atm.

3. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The reaction temperature of the mixed solution generated by the (S1) Bunsen reaction and the magnesium silicate mineral is controlled at 20-90°C.

4. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The reaction temperature of (S3) is controlled at 180-250°C.

5. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The method for separating the CO2 and N2 discharged from (S1) includes liquefaction fractionation and membrane separation, and the separated and collected CO2 is sent to (S3) to participate in the reaction.

6. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The HI gas in (S4) is decomposed into I2 and H2 at 450-500°C in the presence of a catalyst. After I2 and unreacted HI are spray-washed, hydrogen is output as a product.

7. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 1, characterized in that: The magnesium silicate mineral is a natural ore.

8. The method for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 7, characterized in that: The natural ore is serpentine and / or olivine.

9. A device for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4, characterized in that: Including Bunsen reactor, salt generation reactor, condenser, distillation unit, hydrolysis carbonation reactor, MgSO4 dissolver, HI decomposer, flue gas treatment unit, CO2 collection unit; A flue gas treatment device, a Bunsen reactor, a salt generation reactor, a distillation device, and a hydrolysis carbonation reactor are connected in sequence. The hydrolysis carbonation reactor is respectively connected to a MgSO4 dissolver and a HI decomposer. The HI decomposer is connected to a condenser and a Bunsen reactor. The Bunsen reactor is also connected to a CO2 collection device and a hydrolysis carbonation reactor in sequence. The device is operated according to the method described in claim 1.

10. The device for producing hydrogen by thermochemical sulfur-iodine cycle and simultaneously mineralizing CO2 and producing MgSO4 according to claim 9, characterized in that: The Bunsen reactor comprises at least two liquid phase inlets, two liquid phase outlets, and a gas phase inlet, wherein one liquid phase inlet is connected to a condenser for receiving an iodine-containing mixed liquid for spray washing, one liquid phase inlet is used for external water supplementation, and one liquid phase outlet is connected to a condenser for discharging a mixed liquid for spraying; one liquid phase outlet is connected to a salt generation reactor for discharging a mixed liquid for Bunsen reaction; and one gas phase inlet is used for receiving flue gas treated by a flue gas treatment device; The salt generation reactor comprises at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet, and one solid phase outlet; The one liquid phase inlet is used to receive the HI and sulfuric acid mixed solution discharged from the Bunsen reactor; the one liquid phase outlet is connected to the distillation device to discharge the MgI2 and MgSO4 mixed solution; the one solid phase inlet is used to supplement the magnesium silicate ore; and the one solid phase outlet is used to discharge the by-product SiO2; The distillation device comprises at least one liquid phase inlet, one solid phase outlet, and one gas phase outlet; the liquid phase inlet is used to receive a mixed solution of MgI2 and MgSO4, the solid phase outlet is used to discharge MgI2·nH2O crystals and MgSO4·nH2O crystals, and the gas phase outlet is used to discharge water vapor; The hydrolysis carbonation reactor comprises at least one solid phase inlet, one solid phase outlet, two gas phase inlets and one gas phase outlet, wherein the solid phase inlet is used to receive MgI2·nH2O crystals and MgSO4·nH2O crystals, and the solid phase outlet is used to discharge MgCO3 and MgSO4·nH2O crystals; the gas phase inlet is used to receive water vapor from the distillation device, the gas phase inlet is used to receive CO2; and the gas phase outlet is used to discharge HI gas; The HI decomposer is connected to the hydrolysis carbonation reactor, receives the HI gas and decomposes it; The condenser comprises at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet, wherein the liquid phase inlet is connected to the Bunsen reactor for receiving the HI and H2SO4 mixed solution produced by the Bunsen reaction; the liquid phase outlet is connected to the Bunsen reactor for discharging the iodine-containing mixed solution for spray washing; the gas phase inlet is connected to the HI decomposer for receiving HI, I2 and H2; and the gas phase outlet is used to discharge the product hydrogen; The MgSO4 dissolver includes at least one liquid phase inlet, one liquid phase outlet, one solid phase inlet and one solid phase outlet, wherein the liquid phase inlet is used to supplement water from the outside, a liquid phase outlet discharges the MgSO4 solution, a solid phase inlet is connected to the hydrolysis carbonation reactor to receive MgCO3 and MgSO4·nH2O crystals; and a solid phase outlet discharges the byproduct MgCO3 to the outside.

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