JP4783173B2 - Hydrogen production method - Google Patents

Description

  The present invention relates to a hydrogen production method for producing hydrogen by a thermochemical hydrogen production process.

  As one vision of the future society, the realization of a hydrogen energy society using hydrogen as an energy medium is attracting attention, and several promising hydrogen production methods are known.

Among several hydrogen production methods, the IS method (Iodine-Sulfur method), which is a thermochemical hydrogen production process, is a method for producing hydrogen by thermochemically decomposing water while internally circulating iodine and sulfuric acid. (See, for example, Patent Document 1 and Non-Patent Document 1).

  As shown in FIG. 14, this IS method mainly supplies three processes (Bunsen reaction process 201, hydrogen iodide decomposition process 202, Water 210 is converted into hydrogen 206 and oxygen 209 through an internal circulation by the sulfuric acid decomposition step 203). In this IS method, a high temperature gas furnace or the like is used as a heat source.

  In the Bunsen reaction step 201, water 210, iodine 207, and sulfur dioxide 208 are changed to hydrogen iodide (HI) 204 and sulfuric acid 205 via a thermochemical process. Next, in the hydrogen iodide decomposition step 202, the hydrogen iodide 204 generated in the previous step 201 is decomposed into hydrogen 206 and iodine 207 by heating. Next, in the sulfuric acid decomposition step 203, the one sulfuric acid 205 produced in the Bunsen reaction step 201 is also decomposed into oxygen 209, water 210, and sulfur dioxide 208 by heating. The decomposed iodine 207, water 210, and sulfur dioxide 208 are recycled to the Bunsen reaction step 201, and hydrogen 206 and oxygen 209 can be taken out.

  The most important index in all hydrogen production methods for realizing this hydrogen energy society is its hydrogen generation efficiency or thermal efficiency, and is to make this thermal efficiency as high as possible. The thermal efficiency here is defined by thermal efficiency = (combustion heat amount of generated hydrogen) / (total heat amount used for hydrogen generation).

  In the IS method, the hydrogen iodide decomposition step is an important step directly related to hydrogen production. Theoretically, the energy required for hydrogen iodide decomposition is smaller than that for sulfuric acid decomposition. In practice, however, the concentration of hydrogen iodide produced by the Bunsen reaction is usually [hydrogen iodide] / ([hydrogen iodide] + [water]) because hydrogen iodide and water have an azeotropic composition. Cannot exceed 57 wt%, which requires a large amount of energy to separate water and hydrogen iodide.

  In order to obtain high-concentration hydrogen iodide having an azeotropic composition or higher, a technique using an electrolytic electrodialysis method is known (see Non-Patent Document 2).

In the hydrogen iodide decomposition step, conventionally, a process flow for thermal decomposition using a hydrogen iodide decomposition catalyst such as platinum is employed. However, since the equilibrium decomposition rate of hydrogen iodide is as small as about 21% at 450 ° C., a high hydrogen production rate was not obtained. For this reason, since it is necessary to increase the final decomposition rate by making the hydrogen iodide decomposition apparatus and the hydrogen purification apparatus multistage and recirculating undecomposed hydrogen iodide, the thermal efficiency is poor. As a method for increasing the decomposition rate of hydrogen iodide, there is a technique for increasing the decomposition rate of hydrogen iodide by removing hydrogen generated by decomposition of hydrogen iodide outside the system using a hydrogen permeable membrane to shift the decomposition equilibrium. It is known (see Non-Patent Document 3).
JP 2005-41764 A JH Norman et al., GA-A 16300, 1981 K. Onuki, et al., Electro-electrodialysis of hydriodic acid in the presence of iodine at elevated temperature, J. Membr. Sci., 192, 193-199 (2001) Gab-Jin Hwang and Kaoru Onuki, J. Membrane Science, 194 (2001) 207-215

  In the conventional IS method described above, the hydrogen iodide decomposition step is an important step directly related to hydrogen production. Theoretically, the energy required for the hydrogen iodide decomposition is smaller than the energy required for the sulfuric acid decomposition.

  However, in practice, the concentration of hydrogen iodide produced by the Bunsen reaction is usually [hydrogen iodide] / ([hydrogen iodide] + [water] because hydrogen iodide and water have an azeotropic composition. )) Cannot exceed 57 wt%, and for this reason, there is a problem that a large amount of energy is required to separate water and hydrogen iodide.

  Moreover, in order to obtain high-concentration hydrogen iodide having an azeotropic composition or higher in the conventional IS method, it has been studied to use an electrolytic electrodialysis method, but it is difficult to separate iodide ions and hydrated water. There was a problem.

  Furthermore, in the conventional hydrogen iodide decomposition step, the process flow is thermally decomposed using a hydrogen iodide decomposition catalyst such as platinum. Since the equilibrium decomposition rate of hydrogen iodide was as small as about 21% at 450 ° C., a high hydrogen production rate could not be obtained. For this reason, it is necessary to increase the final decomposition rate by, for example, recirculating undecomposed hydrogen iodide by using a multistage hydrogen iodide decomposition apparatus and a hydrogen purification apparatus.

  However, when trying to increase the hydrogen iodide decomposition rate, there is a problem that the scale of the apparatus increases, the thermal efficiency decreases, or the hydrogen production cost increases, making it difficult to achieve economically.

  In addition, the hydrogen iodide decomposition apparatus using a hydrogen permeable membrane also has problems such as the durability of the membrane and the pressure of hydrogen, which is a product, is lowered because hydrogen needs to be high pressure to permeate the membrane.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a hydrogen production method capable of generating hydrogen with high efficiency by producing a liquid containing high-concentration hydrogen iodide in the Bunsen process. .

In order to achieve the above object, the present invention provides a hydrogen production method for producing hydrogen by thermochemically decomposing water while internally circulating iodine and sulfur dioxide, and the sulfur dioxide under pressure conditions of atmospheric pressure or higher. A sulfur dioxide dissolving step in which water is dissolved, and water in which sulfur dioxide is dissolved under pressure conditions above atmospheric pressure react with iodine to produce hydrogen iodide and sulfuric acid. The Bunsen heavy liquid produced in this pressurized Bunsen process is separated from the Bunsen heavy liquid rich in hydrogen iodide and the Bunsen light liquid rich in sulfuric acid by supplying an excess amount of iodine. A distillation process in which hydrogen iodide is separated by distillation under pressure conditions above atmospheric pressure, and hydrogen iodide separated in this distillation process is decomposed with thermal energy to generate hydrogen and fix the generated iodine The hydrogen iodide decomposition / iodine fixing step, the iodine separation step for separating iodine fixed in the hydrogen iodide decomposition / iodine fixation step, and the Bunsen light liquid produced in the pressure Bunsen step are converted into the sulfur dioxide. A sulfuric acid decomposition step that decomposes into oxygen and water, a recycling step that recycles the bottom solution stored in the bottom of the can in the distillation step into the pressurized Bunsen step, and iodine added in the iodine separation step. A membrane for concentrating the bottom liquid of the distillation step, comprising: a recycling step for recycling to the pressure bunsen step; and a recycling step for recycling the sulfur dioxide generated in the sulfuric acid decomposition step to the sulfur dioxide dissolving step. A dilute process comprising a separation process, wherein the bottom liquid concentrated in the membrane separation process is recycled to the distillation process and the separated water is the main component. That recycled to the pressure Bunsen step, it is characterized in.

  In order to achieve the above object, the present invention provides a hydrogen production method for producing hydrogen by thermochemically decomposing water while internally circulating iodine and sulfur dioxide, under the pressurizing condition at atmospheric pressure or higher. A sulfur dioxide dissolution process for dissolving sulfur dioxide in water, and reacting the iodine dissolved with water dissolved in sulfur dioxide under pressure conditions higher than atmospheric pressure to produce hydrogen iodide and sulfuric acid. A pressurized Bunsen process that separates specific gravity into a Bunsen heavy liquid containing a large amount of hydrogen iodide and a Bunsen light liquid containing a large amount of sulfuric acid by supplying an excess amount of excess iodine, and the Bunsen heavy produced in this pressurized Bunsen process. The evaporation step of separating the hydrogen iodide by evaporating the liquid under a pressure condition of atmospheric pressure or higher, and the hydrogen iodide separated in the evaporation step with thermal energy to generate hydrogen and the generated iodine The hydrogen iodide decomposition / iodine fixation step to be immobilized, the iodine separation step to separate the iodine fixed in the hydrogen iodide decomposition / iodine fixation step, and the Bunsen light liquid produced in the pressure Bunsen step The sulfuric acid decomposition step that decomposes into sulfur dioxide, oxygen, and water, the recycling step that recycles the bottom liquid stored in the bottom of the can in the evaporation step into the pressurized Bunsen step, and the iodine separated in the iodine separation step It has a recycling process which recycles to the pressurization Bunsen process, and a recycling process which recycles the sulfur dioxide produced | generated by the said sulfuric acid decomposition process to the said sulfur dioxide melt | dissolution process.

  According to the hydrogen production method of the present invention, a liquid containing hydrogen iodide having a concentration higher than that of the azeotropic composition is generated in a pressurized bunsen process in which water in which sulfur dioxide is dissolved and iodine are reacted under a pressurized condition of atmospheric pressure or higher. By doing so, hydrogen can be generated with high efficiency.

  Embodiments of a hydrogen production method according to the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

  FIG. 1 is a block diagram showing a schematic configuration of the hydrogen production method according to the first embodiment of the present invention.

  As shown in the figure, this hydrogen production method includes a sulfur dioxide dissolving step 7 for dissolving sulfur dioxide 111 in water 101 under a pressurizing condition of atmospheric pressure or higher. The sulfur dioxide 111 is supplied to the sulfur dioxide dissolving step 7 via the compressor 24. This water 101 is supplied to the sulfur dioxide dissolving step 7 via the pump 25. The sulfur dioxide 111 and the water 101 dissolved under the pressurizing condition of the atmospheric pressure or higher are supplied to the pressurizing bunsen process 1.

  In this pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. The iodine 108 is supplied to the pressurization bunsen process 1 through the pumps 22 and 21. At this time, excess iodine 108 exceeding the stoichiometric amount is supplied. By supplying this excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is produced. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the distillation process 2. In this distillation step 2, the introduced Bunsen heavy liquid 104 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the distillation step 2 is introduced into the hydrogen iodide decomposition / iodine fixing step 3 while adjusting the pressure by the pressure regulating valve 8. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  On the other hand, the Bunsen light liquid 110 containing a large amount of sulfuric acid 115 produced in the pressure Bunsen process 1 is introduced into the sulfuric acid decomposition process 6. In the sulfuric acid decomposition step 6, the introduced Bunsen light liquid 110 is heated and decomposed into sulfur dioxide 111, oxygen 103 and water 101. The generated oxygen 103 is recovered while adjusting the pressure by the pressure adjusting valve 9.

  In addition, the can bottom liquid 107 stored in the bottom of the can in the distillation step 2 is recycled to the pressure bunsen step 1 through the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101.

  The iodine 108 separated in the iodine separation step 4 is recycled to the pressure bunsen step 1 via the pump 22. Further, the sulfur dioxide 111, oxygen 103 and water 101 decomposed in the sulfuric acid decomposition step 6 are supplied to the sulfur dioxide dissolving step 7 through the compressor 24 and recycled.

  FIG. 2 is a graph showing the relationship between the concentration of hydrogen iodide 105 in the Bunsen heavy liquid 104 and the operating pressure.

  As shown in this figure, the hydrogen iodide 105 concentration contained in the Bunsen heavy liquid 104 generated in the pressurized Bunsen process 1 of FIG. 1 is shown. Here, the hydrogen iodide 105 concentration represents [hydrogen iodide] / ([hydrogen iodide] + [water]) in weight%.

  This hydrogen iodide and water have an azeotropic composition and cannot exceed 57 wt% at normal pressure. However, it has been found that a hydrogen iodide concentration exceeding 57 wt% at normal pressure can be obtained by pressurizing the hydrogen iodide and water.

  It was confirmed that almost 100% hydrogen iodide can be separated by distilling the heavy liquid obtained in the pressure bunsen step 1 under a pressure of 0.7 MPaG. This pressure condition was 0.7 MPaG because the vapor pressure of hydrogen iodide at 20 ° C. was 0.756 MPa. Therefore, the top component of the column was converted into a liquid phase with a condenser at the top of the distillation column, and this was refluxed. This is so that a rectification effect can be obtained. The obtained almost 100% of hydrogen iodide 105 can be supplied to the hydrogen iodide decomposition / iodine fixing step 3.

  FIG. 3 is a graph showing the basic test results of the hydrogen iodide decomposition / iodine fixing step and the iodine separation step.

  As shown in this figure, the reaction tube was filled with platinum-supported alumina as a hydrogen iodide decomposition catalyst. Further, metallic cobalt (foamed) was sequentially filled in layers as an iodine fixing substance. The test result when the basic test of the hydrogen iodide decomposition | disassembly and iodine fixation process 3 of FIG. 1 and the iodine separation process 4 was performed in the state filled with this catalyst is shown.

In this test, the same mass was filled with platinum-supported alumina and metallic cobalt. As shown in FIG. 3A, in the hydrogen iodide decomposition / iodine fixing step, hydrogen iodide gas 105 was supplied at GHSV140h- ¹ . Moreover, as shown in FIG.3 (b), the nitrogen gas 116 was supplied by GHSV140h- ¹ at the iodine separation process. The operating temperature was 400 ° C. in the hydrogen iodide decomposition / iodine fixing step and 650 ° C. in the iodine separation step. As shown in FIG. 3 (c), it was found that a hydrogen production rate greatly exceeding the thermodynamic equilibrium value of 21% at 400 ° C. was obtained.

  The above-mentioned hydrogen iodide decomposition and iodine fixation can be confirmed by the following formula. In the hydrogen iodide decomposition / iodine fixing step, iodine is generated by decomposing hydrogen iodide as shown in the following formula (1). Next, as the following formula (2) shows, the generated iodine is immobilized. Moreover, in an iodine separation process, it turns out that the reactivity can be recovered | restored by isolate | separating the fixed iodine as the following (3) Formula shows.

(Hydrogen iodide decomposition / iodine fixation process)
2HI → H ₂ + I ₂ (1)
Co + I ₂ → CoI ₂ (2)
(Iodine separation process)
CoI ₂ → Co + I ₂ (3)
Here, based on the above test results, a system capable of continuously producing hydrogen by alternately repeating the hydrogen iodide decomposition / iodine fixing step and the iodine separation step will be described.

  FIG. 4 is a configuration diagram showing a schematic configuration of a hydrogen iodide decomposition / iodine fixation process flow (fixed bed batch switching).

  As shown in the figure, the configuration related to the hydrogen iodide decomposition / iodine fixation process flow (fixed bed batch switching) is divided into a hydrogen iodide decomposition catalyst packed bed 31 and an iodine fixed substance packed bed 32. While one hydrogen iodide decomposition catalyst packed bed 31 was provided, four iodine fixed substance packed layers 32 were provided in the subsequent stage, and were installed in parallel. Three sets of these sets are installed in series.

  In the hydrogen iodide decomposition catalyst packed bed 31, hydrogen iodide 105 is decomposed into hydrogen 102 and iodine 108 as indicated by the above formula (1). In the iodine immobilization substance packed layer 32, as shown in the above formula (2), iodine 108 generated by the reaction of the formula (1) is fixed.

  In the present embodiment configured as described above, only hydrogen iodide 105 and hydrogen 102 which are not decomposed in the former stage are supplied to the hydrogen iodide decomposition catalyst packed bed 31 in the latter stage. In this hydrogen iodide decomposition catalyst packed bed 31, hydrogen iodide 105 is further decomposed into hydrogen 102 and iodine 108. The decomposed iodine 108 is fixed and separated in the subsequent iodine-immobilized substance packed bed 32.

  According to the present embodiment, these treatments are sequentially performed, and the total hydrogen iodide decomposition efficiency (hydrogen generation rate) can be increased.

  In the middle of this operation, when the filling substance approaches the iodine immobilization capacity in the iodine immobilization substance filling layer 32, the other iodine immobilization substance filling layer 32 installed in parallel is switched. By this switching, the iodine fixing ability can be maintained above a certain level.

  The iodine immobilization substance packed bed 32 in which the filling substance immobilizes iodine 108 close to its capacity separates the immobilized iodine 108 as shown in the above formula (3) by changing temperature or / and pressure. The iodine-immobilized substance 32 is regenerated.

  As an example, four iodine-immobilized substance packed layers 32 are installed in parallel. As described above, in each packed bed 32, for example, when metallic cobalt is used as the iodine immobilization substance, four types of “iodine immobilization” → “temperature increase” → “iodine separation / immobilization substance regeneration” → “temperature decrease”. By operating the mode with the phase shifted, continuous operation becomes possible. In addition, it is also possible to use a fluid element as a switching device for the iodine-immobilized substance-filled layer 32 and to have a system without a driving part in the high temperature part.

  FIG. 5 is a configuration diagram showing a schematic configuration of a hydrogen iodide decomposition / iodine fixation process flow (moving bed). In this figure, a moving bed is provided in place of the fixed bed batch switching in FIG. 4, and the same or similar parts as in FIG.

  As shown in FIG. 5A, the configuration related to the hydrogen iodide decomposition / iodine fixation process flow (moving bed) is divided into a hydrogen iodide decomposition catalyst packed bed 31 and an iodine fixed substance packed bed 32. One hydrogen iodide decomposition catalyst packed bed 31 is installed, whereas one iodine fixed substance packed bed 32 is installed in the subsequent stage. Three sets of these sets are installed in series.

As shown in FIG. 5 (b), this iodine-immobilized substance packed layer 32 has a rotating cylinder 203. The rotating cylinder 203 rotates at a constant speed. That is, there is an iodine fixing area 204 to which hydrogen iodide 105 or hydrogen iodide 105 or hydrogen 102 is supplied, and an iodine separation area 205 to which an inert gas (N ₂ , He, Ne, Ar, etc.) 201 is supplied. To do.

  In the present embodiment configured as described above, in the iodine fixing area 204, the iodine 108 generated by the reaction of the formula (1) is fixed as shown by the formula (2). Due to the immobilization of iodine 108, only hydrogen iodide 105 and hydrogen 102 that have not been decomposed in the previous stage are supplied to the hydrogen iodide decomposition catalyst packed bed 31 in the subsequent stage.

  In the subsequent hydrogen iodide decomposition catalyst packed bed 31, hydrogen iodide 105 is further decomposed into hydrogen 102 and iodine 108. In the subsequent iodine-immobilized substance packed bed 32, the decomposed iodine 108 is immobilized and separated.

  As shown in FIG. 5B, each iodine-immobilized substance packed bed 32 rotates at a constant speed, and when the packing reaches the iodine separation area 205, as shown in the above formula (3), the fixed The converted iodine 108 is separated, and the iodine fixed substance 32 is regenerated. When the regenerated iodine-immobilized substance 32 rotates and reaches the iodine-fixed area 205, the iodine 108 produced by the reaction of the formula (1) is immobilized as shown in the formula (2) again. Is done. By this operation, the hydrogen iodide decomposition / iodine fixing step 3 and the iodine separation step 4 are continuously operated.

  According to the present embodiment, the above-described treatment can be sequentially performed to increase the overall hydrogen iodide decomposition efficiency (hydrogen generation rate).

  FIG. 6 is a configuration diagram showing a schematic configuration of a modified example of the hydrogen iodide decomposition / iodine fixation process flow (moving bed). In this figure, a moving bed is provided in place of the fixed bed batch switching shown in FIG. 5, and the same or similar parts as in FIG.

  As shown in FIG. 6A, the configuration related to the hydrogen iodide decomposition / iodine fixation process flow (moving bed) is divided into a hydrogen iodide decomposition catalyst packed bed 31 and an iodine fixed substance packed bed 32. While one hydrogen iodide decomposition catalyst packed bed 31 is installed, two iodine fixed substance packed beds 32 are installed in the subsequent stage. Three sets of these sets are installed in series.

  As shown in FIG. 6B, the iodine fixed substance layer 32 is a fluidized bed, one having an iodine fixed layer 32a and the other having an iodine separation layer 32b. Hydrogen iodide 105 or hydrogen iodide 105 and hydrogen 102 are supplied to the iodine fixed layer 32a. An inert gas 116 is supplied to the iodine separation layer 32b.

  In the iodine fixing layer 32a, as shown in the above formula (2), the iodine 108 generated by the reaction of the formula (1) is fixed. By this reaction, only hydrogen iodide 105 and hydrogen 102 which are not decomposed in the previous stage are supplied to the hydrogen iodide decomposition catalyst packed bed 31 in the subsequent stage. In the subsequent hydrogen iodide decomposition catalyst packed bed 31, the hydrogen iodide 105 is further decomposed into hydrogen 102 and iodine 108. In the subsequent iodine-immobilized substance layer 32, iodine 108 is immobilized by the iodine-immobilized layer 32a, and iodine 108 is separated by the next iodine separation layer 32b.

  In the present embodiment configured as described above, the iodine-immobilized substance layer 32 is a fluidized bed, and a part of the iodine-immobilized substance is continuously extracted and transferred from the iodine-immobilized layer 32a to the iodine separation layer 32b. Is done. In the iodine separation layer 32b, as indicated by the above formula (3), the immobilized iodine 108 is separated to regenerate the iodine fixed substance. This iodine separation layer 32b is also a fluidized bed, and a part of the regenerated iodine-immobilized substance is continuously extracted and transferred to the iodine-immobilized layer 32a.

  According to the present embodiment, the continuous operation is performed by repeating the hydrogen iodide decomposition / iodine fixing step 3 and the iodine separation step 4 while regenerating the iodine fixing substance. Thus, these treatments can be sequentially performed to increase the overall hydrogen iodide decomposition efficiency (hydrogen generation rate).

  FIG. 7 is a block diagram showing a schematic configuration of the hydrogen production method according to the second embodiment of the present invention. In this figure, an undecomposed hydrogen iodide separation step 5 is added to the step of FIG. 1, and the same or similar parts as in FIG. .

  As shown in this figure, in the pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. At this time, excess iodine 108 exceeding the stoichiometric amount is supplied. By supplying this excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is produced. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the distillation process 2. In this distillation step 2, the introduced Bunsen heavy liquid 104 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the distillation step 2 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In the undecomposed hydrogen iodide separation step 5, the undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced and reheated to generate hydrogen 102. In addition, the hydrogen iodide 105 which has not been decomposed is returned to the pressurization Bunsen process 1 of the previous process through the pump 23 together with the water 101.

  In this embodiment configured as described above, an undecomposed hydrogen iodide separation step 5 for purifying hydrogen generated in the hydrogen iodide decomposition / iodine fixation step 3 is provided after the hydrogen iodide decomposition / iodine fixation step 3. In addition, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced and reheated to generate hydrogen 102.

  According to the present embodiment, the purity of the product hydrogen 102 can be maintained even when the decomposition rate of the hydrogen iodide 105 in the hydrogen iodide decomposition / iodine fixing step 3 is not sufficient.

  FIG. 8 is a block diagram showing a schematic configuration of the hydrogen production method according to the third embodiment of the present invention. This figure is provided by adding a membrane separation process 10 to the process of FIG. 7, and the same or similar parts as in FIG.

  As shown in this figure, in the pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. At this time, excess iodine 108 exceeding the stoichiometric amount is supplied. By supplying this excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is produced. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the distillation process 2. In this distillation step 2, the introduced Bunsen heavy liquid 104 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the distillation step 2 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In the undecomposed hydrogen iodide separation step 5, the undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced and reheated to generate hydrogen 102.

  On the other hand, the can bottom liquid 107 stored in the bottom of the can in the distillation step 2 is supplied to the membrane separation step 10 via the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101. In this membrane separation process 10, a part of water is removed, and this bottom liquid 107 is concentrated.

  The concentrated liquid 120 concentrated in the distillation step 2 is recycled to the inlet of the distillation step 2. In the distillation step 2, the introduced concentrated liquid 120 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  On the other hand, the dilute liquid 121 mainly composed of the water 101 separated in the membrane separation step 10 is recycled to the pressure Bunsen step 1. The iodine 108 separated in the iodine separation step 4 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are also recycled to the pressurized Bunsen step 1.

  The membrane used in the membrane separation step 10 is preferably a reverse osmosis membrane made of an inorganic material such as carbon that can withstand corrosive use conditions.

  In this embodiment configured as described above, by providing a membrane separation step 10 for concentrating the bottom solution 107 of the distillation step 2, the water is removed from the bottom solution 107 of the distillation step 2, thereby concentrating. Thus, it can be recycled to the distillation step 2.

  According to the present embodiment, the membrane separation step 10 is added, and the concentrated liquid 120 is distilled under a pressurized condition of atmospheric pressure or higher to increase the overall hydrogen iodide decomposition efficiency (hydrogen generation rate). Can do.

  FIG. 9 is a block diagram showing a schematic configuration of the hydrogen production method according to the fourth embodiment of the present invention. In this figure, a membrane separation step (hydrogen iodide concentration) 11 is provided instead of the membrane separation step 10 (concentration) in FIG. 8, and the same or similar parts as in FIG. Therefore, redundant explanation is omitted.

  As shown in this figure, in the pressurized bunsen process 1, sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition are reacted to produce hydrogen iodide 105 and sulfuric acid 115. By supplying excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is generated. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  In this pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. By supplying excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is generated. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the distillation process 2. In this distillation step 2, the introduced Bunsen heavy liquid 104 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the distillation step 2 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The hydrogen iodide 105 separated in the distillation step 2 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In this undecomposed hydrogen iodide separation step 5, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step is introduced and reheated to generate hydrogen 102.

  On the other hand, the can bottom liquid 107 stored in the bottom of the can in the distillation step 2 is supplied to the membrane separation step 11 via the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101. Further, the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 is also supplied to the membrane separation step 11 through the pump 23.

  In this membrane separation step 11, the bottom solution 107 of the distillation step 2 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are brought into contact with each other through a membrane, whereby the bottom solution 107 of the distillation step 2 is contacted. The concentration of hydrogen iodide 105 therein is increased. The concentrated stool solution 120 enriched with hydrogen iodide 105 is recycled to the inlet of the distillation step 2.

  On the other hand, the dilute liquid 121 mainly composed of the water 101 separated in the membrane separation step 10 is recycled to the pressure Bunsen step 1. The iodine 108 separated in the iodine separation step 4 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are also recycled to the pressurized Bunsen step 1.

  The membrane used in the membrane separation step 11 is a diffusion dialysis membrane, a mosaic charge membrane, or the like, and diffusion dialysis is performed using a concentration difference between the two contacting through this membrane as a driving force.

  As described above, the bottom liquid 107 in the distillation step 2 contains water 101 and iodine 108 in addition to the hydrogen iodide 105. On the other hand, the hydrogen iodide 105 line separated in the undecomposed hydrogen iodide separation step 5 contains hydrogen iodide 105 and water 101. The bottom solution 107 of the distillation step 2 has a concentration of hydrogen iodide 105 in the whole solution due to the iodine 108 contained in a large amount. It is lower than the hydrogen iodide 105 concentration in this line. Through the diffusion dialysis membrane, the hydrogen iodide 105 moves from the hydrogen iodide 105 line side to the bottom liquid 107 side of the distillation step 2 and is concentrated.

  According to the present embodiment, the total hydrogen iodide decomposition efficiency (hydrogen generation rate) can be increased by adding the membrane separation step 11.

  FIG. 10 is a block diagram showing a schematic configuration of the hydrogen production method according to the fifth embodiment of the present invention. In this figure, an evaporation step 12 is provided instead of the distillation step 2 in FIG. 1, and the same or similar parts as in FIG.

  As shown in the figure, this hydrogen production method includes a sulfur dioxide dissolving step 7 for dissolving sulfur dioxide 111 in water 101 under a pressurizing condition of atmospheric pressure or higher. The sulfur dioxide 111 is supplied to the sulfur dioxide dissolving step 7 via the compressor 24. This water 101 is supplied to the sulfur dioxide dissolving step 7 via the pump 25. The sulfur dioxide 111 and the water 101 dissolved under the pressurizing condition of the atmospheric pressure or higher are supplied to the pressurizing bunsen process 1.

  In this pressurized bunsen process 1, sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition are reacted to produce hydrogen iodide 105 and sulfuric acid 115. At this time, excess iodine 108 exceeding the stoichiometric amount is supplied. By supplying this excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is produced. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the evaporation process 12. In the evaporation step 12, the introduced Bunsen heavy liquid 104 is evaporated under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the evaporation step 12 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  On the other hand, the Bunsen light liquid 110 containing a large amount of sulfuric acid 115 produced in the pressure Bunsen process 1 is introduced into the sulfuric acid decomposition process 6. In the sulfuric acid decomposition step 6, the introduced Bunsen light liquid 110 is heated and decomposed into sulfur dioxide 111, oxygen 103 and water 101. The generated oxygen 103 is recovered while adjusting the pressure by the pressure adjusting valve 8.

  The can bottom liquid 107 stored in the bottom of the can in the evaporation step 12 is recycled to the pressure bunsen step 1 through the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101.

  The iodine 108 separated in the iodine separation step 4 is recycled to the pressure bunsen step 1 via the pump 22. Further, the sulfur dioxide 111, oxygen 103 and water 101 decomposed in the sulfuric acid decomposition step 6 are supplied to the sulfur dioxide dissolving step 7 through the compressor 24 and recycled.

  In the present embodiment configured as described above, hydrogen iodide is separated from the heavy liquid 104 generated in the pressurized Bunsen process 1 by evaporation. The hydrogen iodide concentration in the heavy liquid 104 produced in the pressurized Bunsen process 1 exceeds 57 wt%, which is an azeotropic composition, as described with reference to FIG. For this reason, if the pressure is released at the outlet of the pressurized Bunsen process 1, evaporation of the hydrogen iodide 105 from the Bunsen heavy liquid 104 starts. In order to accelerate this, it is effective to slightly heat. In any case, the evaporation step 12 may be a simple system.

  According to the present embodiment, by providing the evaporation step 12 which is a simple system, the total hydrogen iodide decomposition efficiency (hydrogen generation rate) can be increased.

  FIG. 11 is a block diagram showing a schematic configuration of the hydrogen production method according to the sixth embodiment of the present invention. In this figure, an undecomposed hydrogen iodide separation step 5 is added to the step of FIG. 10, and the same or similar parts as in FIG. .

  As shown in this figure, in the pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. At this time, excess iodine 108 exceeding the stoichiometric amount is supplied. By supplying this excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is produced. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the evaporation process 12. In the evaporation step 12, the introduced Bunsen heavy liquid 104 is evaporated under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the evaporation step 12 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In this undecomposed hydrogen iodide separation step 5, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step is introduced and reheated to generate hydrogen 102. In addition, the hydrogen iodide 105 which has not been decomposed is returned to the pressurization Bunsen process 1 of the previous process through the pump 23 together with the water 101.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In this undecomposed hydrogen iodide separation step 5, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step is introduced and reheated to generate hydrogen 102. In addition, the hydrogen iodide 105 which has not been decomposed is returned to the pressurization Bunsen process 1 of the previous process through the pump 23 together with the water 101.

  In this embodiment configured as described above, an undecomposed hydrogen iodide separation step 5 for purifying hydrogen generated in the hydrogen iodide decomposition / iodine fixation step 3 is provided after the hydrogen iodide decomposition / iodine fixation step 3. In addition, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step is introduced and reheated to generate hydrogen 102.

  According to the present embodiment, the purity of the product hydrogen 102 can be maintained even when the decomposition rate of the hydrogen iodide 105 in the hydrogen iodide decomposition / iodine fixing step 3 is not sufficient.

  FIG. 12 is a block diagram showing a schematic configuration of the hydrogen production method according to the seventh embodiment of the present invention. In this figure, a membrane separation process 10 is added to the process of FIG. 11, and the same or similar parts as in FIG.

  As shown in this figure, in the pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. By supplying excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is generated. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the evaporation process 12. In the evaporation step 12, the introduced Bunsen heavy liquid 104 is evaporated under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the evaporation step 12 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In the undecomposed hydrogen iodide separation step 5, the undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced and reheated to generate hydrogen 102.

  On the other hand, the can bottom liquid 107 stored in the bottom of the can in the evaporation step 12 is supplied to the membrane separation step 10 via the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101. In the membrane separation step 10, the can bottom liquid 107 is concentrated.

  The concentrated liquid 120 concentrated in the evaporation step 12 is recycled to the inlet of the evaporation step 12. In the evaporation step 12, the introduced concentrated liquid 120 is distilled under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  On the other hand, the diluted liquid 121 mainly composed of water separated in the membrane separation step 10 is recycled to the pressure bunsen step 1. The iodine 108 separated in the iodine separation step 4 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are also recycled to the pressurized Bunsen step 1.

  The membrane used in the membrane separation step 10 is preferably a reverse osmosis membrane made of an inorganic material such as carbon that can withstand corrosive use conditions.

  In this embodiment configured as described above, by providing a membrane separation step 10 for concentrating the bottom liquid 107 in the evaporation step 12, concentration is achieved by removing moisture from the bottom solution 107 in the evaporation step 12. The can bottom liquid 107 in the state can be recycled to the evaporation step 12.

  According to the present embodiment, it is possible to evaporate the concentrated can bottom liquid 107 by adding the membrane separation step 10, so that the total hydrogen iodide decomposition efficiency (hydrogen generation rate) can be increased.

  FIG. 13 is a block diagram showing a schematic configuration of the hydrogen production method according to the eighth embodiment of the present invention. In this figure, a membrane separation step (hydrogen iodide concentration) 11 is provided instead of the membrane separation step (concentration) 10 in FIG. 12, and the same or similar parts as in FIG. Therefore, redundant explanation is omitted.

  As shown in this figure, in the pressurized bunsen process 1, hydrogen iodide 105 and sulfuric acid 115 are produced by reacting sulfur dioxide 111, water 101 and iodine 108 dissolved under this pressurized condition. By supplying excess iodine 108, a Bunsen solution containing hydrogen iodide 105 and sulfuric acid 115 is generated. By heating the Bunsen solution, specific gravity separation is performed into a Bunsen heavy liquid 104 containing a large amount of hydrogen iodide 105 and a Bunsen light liquid 110 containing a large amount of sulfuric acid 115.

  The Bunsen heavy liquid 104 generated in the pressure Bunsen process 1 is introduced into the evaporation process 12. In the evaporation step 12, the introduced Bunsen heavy liquid 104 is evaporated under a pressurized condition of atmospheric pressure or higher to separate the hydrogen iodide 105.

  The hydrogen iodide 105 separated in the evaporation step 12 is introduced into the hydrogen iodide decomposition / iodine fixing step 3. In the hydrogen iodide decomposition / iodine fixing step 3, the introduced hydrogen iodide 105 is decomposed by thermal energy to generate hydrogen 102. At the same time, iodine 108 generated together with hydrogen 102 is immobilized.

  The iodine 108 fixed in the hydrogen iodide decomposition / iodine fixing step 3 is introduced into the iodine separation step 4. In the iodine separation step 4, the introduced fixed iodine 108 is separated.

  An undecomposed hydrogen iodide separation step 5 is provided after the hydrogen iodide decomposition / iodine fixing step 3. In this undecomposed hydrogen iodide separation step 5, undecomposed hydrogen iodide 105 that was not decomposed in the hydrogen iodide decomposition / iodine fixing step is introduced and reheated to generate hydrogen 102.

  On the other hand, the can bottom liquid 107 stored in the bottom of the can in the evaporation step 12 is supplied to the membrane separation step 11 via the pump 21. This can bottom liquid 107 contains hydrogen iodide 105, iodine 108 and water 101. Further, the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 is also supplied to the membrane separation step 11 through the pump 23.

  In this membrane separation step 11, the bottom solution 107 of the evaporation step 12 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are brought into contact with each other through a membrane, and the bottom solution 107 of the evaporation step 12 is contacted. The concentration of hydrogen iodide 105 therein is increased. The concentrated liquid 120 in which the hydrogen iodide 105 is concentrated is recycled to the inlet of the evaporation step 12.

  On the other hand, the dilute liquid 121 mainly composed of the water 101 separated in the membrane separation step 10 is recycled to the pressure Bunsen step 1. The iodine 108 separated in the iodine separation step 4 and the hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 are also recycled to the pressurized Bunsen step 1.

  The membrane used in the membrane separation step 11 is a diffusion dialysis membrane, a mosaic charge membrane, or the like, and diffusion dialysis is performed using a concentration difference between the two contacting through this membrane as a driving force.

  As described above, the bottom liquid 107 in the evaporation step 12 contains water 101 and iodine 108 in addition to the hydrogen iodide 105. On the other hand, the hydrogen iodide 105 line separated in the undecomposed hydrogen iodide separation step 5 contains hydrogen iodide 105 and water 101. The bottom solution 107 of the evaporation step 12 has a hydrogen iodide 105 concentration of hydrogen iodide 105 separated in the undecomposed hydrogen iodide separation step 5 because the iodine 108 contained in a large amount has a hydrogen iodide 105 concentration in the entire solution. It is lower than the hydrogen iodide 105 concentration in this line. Through the diffusion dialysis membrane, the hydrogen iodide 105 moves from the hydrogen iodide 105 line side to the bottom liquid 107 side of the evaporation step 12 and is concentrated.

  According to the present embodiment, by adding the membrane separation step 11, the hydrogen iodide 105 concentrated in the evaporation step 12 can be evaporated, thereby increasing the overall hydrogen iodide decomposition efficiency (hydrogen generation rate). be able to.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention by combining the embodiments of the present invention. it can.

The block diagram which shows schematic structure of the hydrogen production method of the 1st Embodiment of this invention. The graph which shows the relationship between the hydrogen iodide density | concentration in Bunsen heavy liquid, and operating pressure. (A) And (b) is explanatory drawing which shows the basic test of a hydrogen iodide decomposition | disassembly and iodine fixation process, and an iodine separation process, (c) is a graph which shows the test result. (A) And (b) is a block diagram which shows schematic structure of a hydrogen iodide decomposition | disassembly and iodine fixation process flow (fixed bed batch switching). (A) And (b) is a block diagram which shows schematic structure of a hydrogen iodide decomposition | disassembly and iodine fixation process flow (moving bed). (A) And (b) is a block diagram which shows schematic structure of the modification of a hydrogen iodide decomposition | disassembly and iodine fixation process flow (moving bed). The block diagram which shows schematic structure of the hydrogen manufacturing method of the 2nd Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 3rd Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 4th Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 5th Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 6th Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 7th Embodiment of this invention. The block diagram which shows schematic structure of the hydrogen manufacturing method of the 8th Embodiment of this invention. The block diagram which shows schematic structure of the conventional hydrogen production method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pressure bunsen process, 2 ... Distillation process, 3 ... Hydrogen iodide decomposition | disassembly process and iodine fixation process, 4 ... Iodine separation process, 5 ... Undecomposed iodine separation process, 6 ... Sulfuric acid decomposition process, 7 ... Sulfur dioxide dissolution process, 8, 9 ... Pressure regulating valve, 10 ... Membrane separation step (concentration), 11 ... Membrane separation step (hydrogen iodide separation), 12 ... Evaporator, 21, 22, 23, 25 ... Pump, 24 ... Compressor, 31 ... hydrogen iodide decomposition catalyst packed bed, 32 ... iodine fixed substance packed bed, 33 ... iodine fixed substance, 101 ... water, 102 ... hydrogen, 103 ... oxygen, 104 ... Bunsen heavy liquid, 105 ... hydrogen iodide, 107 ... Can bottom liquid, 108 ... Iodine, 110 ... Bunsen light liquid, 111 ... Sulfur dioxide, 115 ... Sulfuric acid, 116 ... Inert gas, 120 ... Concentrated liquid, 116 ... Diluted liquid.

Claims (14)

In a hydrogen production method for producing hydrogen by thermochemically decomposing water while internally circulating iodine and sulfur dioxide,
A sulfur dioxide dissolving step for dissolving the sulfur dioxide in water under a pressure condition of atmospheric pressure or higher,
The iodine is reacted with water in which sulfur dioxide is dissolved under pressure conditions above atmospheric pressure to produce hydrogen iodide and sulfuric acid. At this time, the iodine is supplied by supplying excess iodine in a stoichiometric amount or more. A pressurized Bunsen process for specific gravity separation between a Bunsen heavy liquid rich in hydrogen and a Bunsen light liquid rich in sulfuric acid;
A distillation step of separating hydrogen iodide by distilling the bunsen heavy liquid produced in this pressure bunsen step under a pressure condition of atmospheric pressure or higher;
Hydrogen iodide decomposition / iodine fixing step of decomposing hydrogen iodide separated in this distillation step with heat energy to generate hydrogen and fixing the generated iodine,
An iodine separation step for separating iodine fixed in the hydrogen iodide decomposition / iodine fixation step;
A sulfuric acid decomposition step of decomposing the Bunsen light liquid produced in the pressure Bunsen step into the sulfur dioxide, oxygen and water;
A recycling step of recycling the bottom solution stored in the bottom of the can in the distillation step to the pressurized bunsen step;
A recycling step of recycling the iodine separated in the iodine separation step into the pressure bunsen step;
A recycling step of recycling the sulfur dioxide produced in the sulfuric acid decomposition step to the sulfur dioxide dissolution step, and
A membrane separation step for concentrating the bottom solution of the distillation step is provided, and the bottom solution concentrated in the membrane separation step is recycled to the distillation step and the diluted liquid mainly composed of the separated water is pressurized. Recycling to the Bunsen process,
A method for producing hydrogen.   An undecomposed hydrogen iodide separation step is provided after the hydrogen iodide decomposition / iodine fixing step, and the hydrogen produced in the hydrogen iodide decomposition / iodine fixation step is purified and separated in the undecomposed hydrogen iodide separation step. The hydrogen production method according to claim 1, wherein the hydrogen iodide is recycled to the pressurized Bunsen process. The bottom solution whose hydrogen iodide concentration is increased by bringing the bottom solution of the distillation step into contact with the hydrogen iodide separated in the undecomposed hydrogen iodide separation step through the membrane separation step is recycled to the distillation step . The hydrogen production method according to claim 2, wherein: The hydrogen production method according to any one of claims 1 to 3 , wherein the pressurizing condition in the distillation step is 0.65 MPaG or more . In a hydrogen production method for producing hydrogen by thermochemically decomposing water while internally circulating iodine and sulfur dioxide,
  A sulfur dioxide dissolving step for dissolving the sulfur dioxide in water under a pressure condition of atmospheric pressure or higher,
  The iodine is reacted with water in which sulfur dioxide is dissolved under pressure conditions above atmospheric pressure to produce hydrogen iodide and sulfuric acid. At this time, the iodine is supplied by supplying excess iodine in a stoichiometric amount or more. A pressurized Bunsen process for specific gravity separation between a Bunsen heavy liquid rich in hydrogen and a Bunsen light liquid rich in sulfuric acid;
  An evaporation step of separating hydrogen iodide by evaporating the bunsen heavy liquid produced in the pressure bunsen step under a pressure condition of atmospheric pressure or higher;
  Hydrogen iodide decomposition / iodine fixing step of decomposing hydrogen iodide separated in this evaporation step with heat energy to generate hydrogen and fixing the generated iodine,
  An iodine separation step for separating iodine fixed in the hydrogen iodide decomposition / iodine fixation step;
  A sulfuric acid decomposition step of decomposing the Bunsen light liquid produced in the pressure Bunsen step into the sulfur dioxide, oxygen and water;
  A recycling step of recycling the bottom solution stored in the bottom of the can in the evaporation step to the pressurized bunsen step;
  A recycling step of recycling the iodine separated in the iodine separation step into the pressure bunsen step;
  A recycling step for recycling the sulfur dioxide produced in the sulfuric acid decomposition step to the sulfur dioxide dissolving step;
  A method for producing hydrogen, comprising: An undecomposed hydrogen iodide separation step is provided after the hydrogen iodide decomposition / iodine fixing step, and the hydrogen produced in the hydrogen iodide decomposition / iodine fixation step is purified and separated in the undecomposed hydrogen iodide separation step. 6. The method for producing hydrogen according to claim 5, wherein the hydrogen iodide is recycled to the pressurized bunsen process . A membrane separation step for concentrating the bottom liquid of the evaporation step is provided, and the bottom solution concentrated in the membrane separation step is recycled to the evaporation step, and the diluted liquid mainly composed of the separated water is pressurized. The hydrogen production method according to claim 5 , wherein the hydrogen production method is recycled to a Bunsen process . A membrane separation step is provided at the subsequent stage of the evaporation step, and the hydrogen iodide concentration is obtained by contacting the bottom liquid of the evaporation step and the hydrogen iodide separated in the undecomposed hydrogen iodide separation step through the membrane separation step. The method for producing hydrogen according to claim 7, wherein the can bottom liquid having increased is recycled to the evaporation step . The method for producing hydrogen according to any one of claims 6 to 8 , wherein the pressurizing condition in the evaporation step is 0.1 MPaG to 0.9 MPaG . 10. The hydrogen iodide decomposition / iodine fixing step comprises at least one hydrogen iodide decomposition catalyst packed bed and at least one iodine fixed substance packed bed . The method for producing hydrogen according to 1. The hydrogen iodide decomposition catalyst is composed of at least one compound selected from platinum, palladium, ruthenium, iron, nickel, aluminum, titanium and activated carbon or a mixture thereof, and the iodine fixing substance is cobalt, silver, The method for producing hydrogen according to claim 10, comprising at least one compound selected from iron, zinc, copper, nickel, and activated carbon, or a mixture thereof . The iodine-immobilized substance-packed layer is a set of two or more groups, and one group is subjected to iodine fixation in the hydrogen iodide decomposition / iodine fixation process. The iodine fixed by separating is separated and regenerated, and another iodine-immobilized substance packed layer is switched to be used for iodine fixation, and hydrogen iodide decomposition is continuously performed. Item 11. The method for producing hydrogen according to Item 10 . The iodine fixed substance packed bed is used as a moving bed, and the iodine fixed substance is continuously moved in an iodine fixing step and an iodine separation step, thereby continuously decomposing hydrogen iodide. Item 11. The method for producing hydrogen according to Item 10 . The iodine-immobilized substance packed bed is made into two or more fluidized beds, and the iodine-immobilized substance is continuously moved in an iodine fixing step and an iodine separation step, thereby continuously decomposing hydrogen iodide. The method for producing hydrogen according to claim 10 .

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