JP5134252B2 - Hydrogen production apparatus and method - Google Patents

Description

  The present invention relates to a hydrogen production apparatus and method for producing hydrogen gas by reforming a hydrocarbon-based fuel by a steam reforming reaction or the like. More specifically, the present invention relates to a hydrogen production apparatus and method for efficiently recovering carbon dioxide produced in the reforming process.

As a method for producing a gas rich in hydrogen, which is a fuel gas for a fuel cell or the like, there is a method for producing from a fossil fuel using a steam reforming reaction. This is based on the reaction of obtaining hydrogen and carbon monoxide by hydrolysis of hydrocarbon as shown in the following formula 1 in the case of methane. Furthermore, CO ₂ and hydrogen are obtained from the CO generated by Equation 1 by the reaction of Equation 2.
CH ₄ + H ₂ O → CO + 3H ₂ (Formula 1)
CO + H ₂ O → CO ₂ + H ₂ (Formula 2)

  As a conventional general hydrogen production apparatus 100, there is an apparatus having a pressurizer 101, a reformer 102, a CO converter 103, a PSA 104, and a combustion section 105 as shown in FIG. The source gas is pressurized to about 0.9 MPa by the pressurizer 101 and preheated. When this raw material gas and preheated water vapor undergo a reforming reaction in the reformer 102, a gas containing hydrogen, carbon monoxide, and carbon dioxide is obtained. The reformer 102 is filled with a reforming catalyst (for example, particles in which nickel is supported on alumina particles).

  The output gas is then passed through a CO converter 103 where water vapor is added to the remaining carbon monoxide to obtain carbon dioxide and hydrogen. Here, the composition of the gas obtained after passing through the CO converter 103 is, for example, as shown in the “gas after shift reaction” column in the following Table 1. Further, the gas is dehydrated by removing heat. Then, the composition of each component is as shown in the “After dehydration” column of Table 1. In both Table 1 and the following similar tables, the ratio of each gas is shown in mole fraction. In addition, the ratio of each gas in the following sentences is also shown in mole fraction unless otherwise specified. FIG. 13 shows chemical formulas of main reactions that occur in the apparatus and standard reaction temperatures.

  The hydrogen-rich gas obtained here is purified to a higher purity hydrogen gas by the PSA 104. Here, PSA (Pressure Swing Adsorption) 104 is a hydrogen purifier using an adsorbent. In the PSA 104, high hydrogen product hydrogen gas (for example, about 99.99%) is purified by utilizing the fact that hydrogen is hardly adsorbed due to the difference in the adsorption speed of various gas components.

Other gas components (CO, CH ₄ , CO _2, etc.) adsorbed by the PSA 104 are appropriately removed from the adsorbent by depressurization and washed away using part of the product hydrogen. The hydrogen used at that time is usually 30% or more of the product hydrogen. The composition of the gas (off gas) discharged from the PSA 104 is as shown in Table 2 below, for example. Therefore, this off-gas is combusted in the combustion unit 105, and the heat is used for heating the reformer 102, preheating the raw material gas, and the like.

In this conventional hydrogen production apparatus 100, the total hydrogen production efficiency was about 67%. The hydrogen production efficiency is a numerical value calculated by the following formula.
Hydrogen production efficiency (%) = calorific value of product hydrogen / (caloric value of raw material + electric power consumption)
Here, the raw material is a raw material gas such as city gas. This hydrogen production efficiency is not very excellent compared to the conventional production efficiency of various energies, and further higher efficiency has been desired. There was also a need to reduce carbon dioxide emissions.

  On the other hand, in recent years, a carbon dioxide absorption type hydrogen production technique has been proposed (see, for example, Patent Document 1 and Patent Document 2). In the apparatuses disclosed in these documents, a carbon dioxide absorbent is filled together with a fuel reforming catalyst in a reactor that performs fuel reforming. In the hydrogen production method using the apparatuses described in these documents, a raw material gas and steam are introduced into a reactor, and a steam reforming reaction and a carbon dioxide absorption reaction are performed in parallel.

  Here, there is a limit to the amount of carbon dioxide that can be absorbed by the carbon dioxide absorbent in the reactor. Therefore, after absorbing a certain amount of carbon dioxide, it is necessary to release the absorbed carbon dioxide so that the carbon dioxide absorbent can absorb carbon dioxide again (referred to as “regeneration”). . In these documents, the carbon dioxide absorbent is regenerated by raising the temperature of the carbon dioxide absorbent that has absorbed carbon dioxide. This utilizes the fact that the amount of carbon dioxide that can be absorbed by the carbon dioxide absorbent varies depending on the temperature and decreases at high temperatures.

  Therefore, when a certain amount of carbon dioxide is absorbed by the carbon dioxide absorbent in the reactor, the temperature of the reactor is raised to a temperature at which the carbon dioxide absorbent releases carbon dioxide and is regenerated. Then, the raw material gas and water vapor are again introduced into the reactor in which the carbon dioxide absorbent has been regenerated. Then, further steam reforming reaction can be caused. At this time, the steam reforming reaction is an endothermic reaction, and the carbon dioxide absorption reaction by the carbon dioxide absorbent is an exothermic reaction. Therefore, the heat energy required for the steam reforming reaction is added to the heat generated by the carbon dioxide absorption reaction. Can be covered by By repeating these procedures, hydrogen gas is produced.

In this production method, the temperature of the reactor is repeatedly changed between the reaction temperature of the reforming step and the carbon dioxide absorption step (for example, about 600 ° C.) and the regeneration temperature of the carbon dioxide absorbent (for example, about 900 ° C.). . Therefore, it will be called the temperature swing method.
JP 2003-54927 A JP 2003-212510 A

However, the above-described temperature swing type carbon dioxide absorption type hydrogen production apparatus has the following problems.
(1) Since the temperature rise and fall is repeated between the reaction temperature and the regeneration temperature, the reaction tube is repeatedly expanded and contracted, and the reaction tube itself and the catalyst in the tube may be damaged.
(2) Since the regeneration process of the carbon dioxide absorbent is performed at a very high temperature, it is necessary to use a special material as the reaction tube which is a container of the reactor.

(3) The heat conduction resistance of the catalyst layer in the reaction tube is large, and it takes time to change the temperature. Therefore, heat dissipation loss is large. In addition, in order to increase the time efficiency, it is necessary to devise such as providing a plurality of reaction tubes and sequentially performing different processes. As a result, the overall size of the equipment tends to increase in size and complexity.
(4) The hydrogen concentration of the gas obtained by this carbon dioxide absorption type apparatus is about 90%, and does not reach the purity (99.99%) required for the product. Therefore, it is necessary to pass PSA, and a part of product hydrogen is used for purging PSA. Furthermore, the PSA off-gas is used as a fuel to heat the reactor. Therefore, the hydrogen production efficiency of the entire system is about 70%, which is not so improved as compared with a conventional hydrogen production apparatus that is not a carbon dioxide recovery type.

  The present invention has been made to solve the problems of the conventional hydrogen production apparatus. In other words, the problem is that the carbon dioxide absorption and release cycle can be realized by a simple method, contributing to simplification and cost reduction of the equipment, and increasing the efficiency of hydrogen production as a whole system. An object of the present invention is to provide a hydrogen production apparatus and method.

  The hydrogen production apparatus of the present invention made for the purpose of solving this problem is a reforming reaction tube containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water, and a carbon dioxide absorbent. And the supply section for supplying the raw material gas to the reforming reaction tube, and the reformed gas output from the reforming reaction tube is separated into a product gas with an increased hydrogen concentration and an off-gas with an increased concentration of non-hydrogen components. And a return unit for returning off-gas from the purification unit to the supply unit, and a carbon dioxide extraction unit for extracting the carbon dioxide rich gas from the reforming reaction tube by depressurizing the reforming reaction tube.

  According to the hydrogen production apparatus of the present invention, the raw material gas is supplied to the reforming reaction tube by the supply unit. Since the reforming reaction tube contains a reforming catalyst, the source gas is reformed. Furthermore, since the carbon dioxide absorbent is also incorporated in the reforming reaction tube, the carbon dioxide generated by the reforming reaction is absorbed by the carbon dioxide absorbent. Therefore, a reformed gas with a low carbon dioxide content is output from the reforming reaction tube. The reformed gas is separated into a product gas with an increased hydrogen concentration and an off-gas with an increased concentration of non-hydrogen components by the purification unit. Since the separated off gas contains almost no carbon dioxide, it can be returned to the supply section and mixed with the raw material gas. Therefore, it is returned to the supply unit by the return unit. That is, the product hydrogen is not used for heating the reforming reaction tube or the like, and only the required amount of fuel needs to be supplied for combustion for these heating. Therefore, the hydrogen production efficiency of the entire system can be increased.

  Furthermore, the carbon dioxide absorbed by the carbon dioxide absorbent is taken out as a carbon dioxide rich gas by the carbon dioxide taking-out part. Thereby, the carbon dioxide absorbent is regenerated. At this time, since the carbon dioxide rich gas is taken out by reducing the pressure of the reforming reaction tube in the carbon dioxide taking-out section, it is not necessary to make the reforming reaction tube particularly high in temperature. For this reason, it is not necessary to use a special material for the reforming reaction tube. Therefore, the carbon dioxide absorption / release cycle can be realized by a simple method of changing the pressure, contributing to simplification and cost reduction of the apparatus.

Further, in the present invention, the reforming step of supplying the raw material gas to the reforming reaction tube and outputting the reformed gas, the regeneration step of reducing the pressure and outputting the carbon dioxide rich gas, and the boosting step of increasing the pressure are repeated in this order. It is desirable to have a control unit to be performed.
In this way, the reforming reaction tube and the carbon dioxide absorption reaction can be caused by repeatedly using the reforming reaction tube.

Furthermore, in the present invention, it is desirable that the gas supplied to the reforming reaction tube in the pressurization step is a mixed gas of a source gas and an off gas.
In this way, off-gas can be further used as part of the raw material, and hydrogen production efficiency can be increased.

  Further, in the present invention, the controller has at least three reforming reaction tubes, and the control unit causes the first reforming reaction tube to perform a reforming step and causes the second reforming reaction tube to perform a regeneration step. A first mode in which the third reforming reaction tube performs a boosting step; a first reforming reaction tube in which a regeneration step is performed; a second reforming reaction tube in which a boosting step is performed; A second mode in which a reforming step is performed in the quality reaction tube, a pressure-increasing step is performed in the first reforming reaction tube, a reforming step is performed in the second reforming reaction tube, and a third reforming reaction is performed. It is desirable to repeatedly perform the third mode in which the tube performs the regeneration process in this order.

  In such a case, the reforming process, the regeneration process, and the boosting process are repeated in this order in each reforming reaction tube. Further, the reforming process is performed in any reforming reaction tube in any of the first mode, the second mode, and the third mode. Therefore, since the reforming process is performed without interruption, the product gas can be obtained continuously.

Furthermore, in the present invention, there is a circulation pipe for selectively connecting the three reforming reaction pipes to each other, and the control unit is in the boosting process from the reforming reaction pipe in the regeneration process before each mode. It is desirable to supply gas to the reforming reaction tube.
For example, when a large amount of carbon dioxide is absorbed by the carbon dioxide absorbent in the reforming process and further absorption becomes difficult, the process proceeds to the regeneration process. For this reason, in the reforming reaction tube at the time of transition to the regeneration process, some gas that has undergone the reforming reaction remains in the vicinity of the outlet. Therefore, by supplying gas from the reforming reaction tube in the regeneration process to the reforming reaction tube in the pressure increasing process, the residual gas can be recovered.

Further, in the present invention, it is desirable that the control unit supplies a part of the reformed gas from the reforming reaction tube in the reforming process to the reforming reaction tube in the pressurizing process at the subsequent stage of each mode.
When the raw material gas is supplied to the reforming reaction tube in the pressurizing step, the removal of the reformed gas cannot be started until the reforming reaction is almost completed for the whole. Therefore, some waiting time is required from the end of the pressurizing process until the reformed gas is taken out. Instead, if a part of the reformed gas is supplied from the reforming reaction tube in the reforming process to the reforming reaction tube in the pressurizing process, the gas in the reforming reaction tube is transferred at the end of the pressurizing process. Contains reformed gas. Therefore, when the process is shifted from the pressure increasing process to the reforming process, the reformed gas can be taken out with almost no waiting time.

Furthermore, in the present invention, it is desirable that the control unit introduces the reformed gas into the reforming reaction tube that has finished the regeneration process temporarily when the mode is switched.
In the regeneration step, the reforming reaction tube is depressurized and carbon dioxide rich gas is taken out. However, a slight amount of carbon dioxide may remain in the reforming reaction tube at the end of the regeneration process. Therefore, if the reformed gas is introduced into the reforming reaction tube that has finished the regeneration process temporarily when the mode is switched, the remaining carbon dioxide can be reliably removed.

  The present invention also uses a reforming reaction tube containing a reforming catalyst that promotes a reforming reaction for generating hydrogen from hydrocarbon and water, and a carbon dioxide absorbent. And a reforming step of causing a reforming reaction to absorb the generated carbon dioxide in a carbon dioxide absorbent and outputting a reformed gas to obtain a product gas having an increased hydrogen concentration of the reformed gas, Regeneration process in which the reforming reaction tube after the reforming process is decompressed to release carbon dioxide from the carbon dioxide absorbent, and the reforming reaction tube after the regeneration process has a concentration of the raw material gas and the non-hydrogen component of the reforming gas. The present invention extends to a hydrogen production method in which a mixed gas with an off-gas having an increased pressure is supplied and the pressure is increased.

  In addition, the present invention uses at least three reforming reaction tubes containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water, and a carbon dioxide absorbent. A first mode in which a reforming step is performed in the quality reaction tube, a regeneration step is performed in the second reforming reaction tube, and a pressure increasing step is performed in the third reforming reaction tube; A second mode in which a regeneration step is performed, a second reforming reaction tube is subjected to a boosting step, a third reforming reaction tube is subjected to a reforming step, and a first reforming reaction tube is subjected to a boosting step. And repeating the third mode in which the second reforming reaction tube performs the reforming process and the third reforming reaction tube performs the regeneration process in this order. The raw material gas and water vapor are supplied to the quality reaction tube to cause the reforming reaction, and the generated carbon dioxide is absorbed by the carbon dioxide absorbent and the reforming gas is absorbed. In the regeneration process, the reforming reaction tube after the reforming process is depressurized to release carbon dioxide from the carbon dioxide absorbent, and before the pressurizing process. Then, the supply of gas from the reforming reaction tube in the regeneration process is pressurized to raise the pressure of the reforming reaction tube. In the latter stage of the boosting process, a part of the reformed gas is supplied from the reforming reaction tube in the reforming process. It extends to a hydrogen production method in which the reforming reaction tube is pressurized.

  A reforming reaction tube containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water, and a downstream of the reforming reaction tube for generating hydrogen from carbon monoxide and water. A converter containing a carbon monoxide conversion catalyst and a carbon dioxide absorbent for promoting a carbon oxide conversion reaction, a supply unit for supplying a raw material gas to the reforming reaction tube, and a reformed gas output from the converter, A refining unit that separates product gas with increased hydrogen concentration and off-gas with increased concentration of non-hydrogen components, a return unit that returns off-gas from the refining unit to the supply unit, and CO2 from the transformer by depressurizing the transformer. You may have a carbon dioxide extraction part which takes out carbon rich gas.

  According to the hydrogen production apparatus of the present invention, the raw material gas is supplied to the reforming reaction tube by the supply unit. Further, the gas reformed in the reforming reaction tube is sent to the downstream transformer. Here, since the carbon dioxide absorbent is built in the transformer, the carbon dioxide produced by the reforming reaction is absorbed by the carbon dioxide absorbent. Therefore, the reformed gas output from the transformer has a low carbon dioxide content. Accordingly, the off-gas separated from the reformed gas also has a low carbon dioxide content. Accordingly, the off-gas can be returned to the supply unit and mixed with the raw material gas. Further, the transformer is decompressed to extract carbon dioxide rich gas. Thereby, the carbon dioxide absorbent is easily regenerated. Therefore, even with this type of equipment, the carbon dioxide absorption and release cycle can be realized in a simple manner, contributing to simplification and cost reduction of the equipment, and increasing the efficiency of hydrogen production as a whole system. be able to.

Furthermore, in the present invention, it is desirable to have a heating section for heating the transformer when the transformer is decompressed by the carbon dioxide take-out section.
In general, the carbon monoxide shift reaction proceeds at a lower temperature than the reforming reaction. For example, it occurs at about 400 to 500 ° C. Therefore, if it has a heating part, when depressurizing the transformer by the carbon dioxide take-out part and take out the carbon dioxide rich gas, the material of the reactor does not require a special material, for example, about 500 to 600 ° C. The transformer can be heated. Therefore, the carbon dioxide rich gas can be taken out more efficiently.

Furthermore, in the present invention, at least two transformers and a control unit are included, and the control unit generates the reforming reaction in the two transformers while causing the reforming reaction tube to perform the reforming reaction. It is desirable to alternately perform an absorption process in which carbon dioxide is absorbed by the carbon dioxide absorbent and a regeneration process in which the carbon dioxide rich gas is released under reduced pressure.
In this way, since the absorption process is performed in any of the transformers, the gas output from the reforming reaction tube can be supplied to the transformer in which the absorption process is performed. Therefore, the reforming reaction can be continuously performed, and the product gas can be continuously obtained. Further, at least three transformers may be provided, and each of the absorption process, the regeneration process, and the boosting process for boosting the transformer may be performed. That is, the control unit causes the reforming reaction tube to perform the reforming reaction, causes the three transformers to perform the absorption process to the first transformer, and causes the second transformer to perform the regeneration process, A fourth mode in which the third transformer performs a boosting process; a first transformer that performs a regeneration process; a second transformer that performs a boosting process; and a third transformer that performs an absorption process. And the sixth mode in which the first transformer performs the boosting process, the second transformer performs the absorption process, and the third transformer performs the regeneration process in this order. You may make it carry out.

  The present invention also provides a reforming reaction tube that incorporates a reforming catalyst that promotes a reforming reaction that generates hydrogen from hydrocarbon and water, and a modification that is provided downstream of the reforming reaction tube and contains a carbon dioxide absorbent. The reformer reaction is performed by supplying the raw material gas and water vapor to the reforming reaction tube, and the reformed gas output from the transformer is converted into a product gas with an increased hydrogen concentration and a non-hydrogen component. The absorption process in which the carbon dioxide produced by the reforming reaction is absorbed by the carbon dioxide absorbent and the regeneration process in which the carbon dioxide-rich gas is released under reduced pressure are alternately separated. This extends to a hydrogen production method in which off-gas is returned to the upstream side of the reforming reaction tube when the transformer is in the regeneration process.

  According to the hydrogen production apparatus and method of the present invention, the absorption / release cycle of carbon dioxide is realized by a simple method, contributing to simplification and cost reduction of the apparatus, and improving the efficiency of hydrogen production as a whole system. Can be raised.

"First form"
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a hydrogen production apparatus using a carbon dioxide recovery type reformer.

  As shown in FIG. 1, the hydrogen production apparatus 1 of this embodiment controls three reforming reaction tubes 11, 12, 13, pumps 14, 15, a drying unit 16, a PSA 17, a combustion unit 18, and these. A control unit 19 is provided. The three reforming reaction tubes 11, 12, and 13 all have the same configuration, and are filled with a reforming catalyst and a carbon dioxide absorbent. As the reforming catalyst, for example, particles in which nickel is supported on alumina particles are used. As the carbon dioxide absorbent, calcium oxide (CaO) is used here.

  The pump 14 is a general gas compressor, and the pump 15 is a general decompressor. The cooling / drying unit 16 is a component that dehydrates the connected gas by removing heat. The PSA 17 is a hydrogen purifier using an adsorbent, similar to the conventional PSA 104 (see FIG. 13) described in the background art section. The combustion section 18 is for burning the raw material gas or the like and heating the reforming reaction tubes 11, 12, 13. The source gas here is a mixed gas of a hydrocarbon-containing gas such as city gas and water (water vapor).

  In addition, the hydrogen production apparatus 1 of the present embodiment communicates between each member and allows various gases to pass therethrough, so that a raw material gas pipe 21, a combustion gas pipe 22, an off gas pipe 23, an input gas pipe 24, an output gas pipe 25, an exhaust gas A gas pipe 26 and a circulating gas pipe 27 are provided. The source gas pipe 21 introduces city gas, which is source gas, into the hydrogen production apparatus 1. The combustion gas pipe 22 branches from the raw material gas pipe 21 and introduces the raw material gas into the combustion unit 18. The off gas pipe 23 introduces the off gas of the PSA 17 into the source gas pipe 21.

  The input gas pipe 24 introduces the gas sent from the pump 14 into each reforming reaction pipe 11, 12, 13. The output gas pipe 25 introduces the output gas from each reforming reaction pipe 11, 12, 13 to the cooling and drying unit 16. The exhaust gas pipe 26 introduces the output gas from each reforming reaction pipe 11, 12, 13 to the pump 15. The circulation gas pipe 27 circulates gas between the reforming reaction pipes 11, 12, 13. The main gas flow direction at each location is indicated by solid arrows in FIG. Moreover, the black circles in the figure indicate the locations where the pipes are connected to each other, and the circulated gases merge or branch at the locations of the black circles.

  Further, as shown in FIG. 1, on-off valves are arranged between the reforming reaction tubes 11, 12, 13 and the input gas pipe 24, output gas pipe 25, exhaust gas pipe 26, and circulation gas pipe 27, respectively. Has been. Open / close valves 31, 32, 33 for communication / closing with the input gas pipe 24, open / close valves 34, 35, 36 for communication / closing with the output gas pipe 25, and communication / closing with the exhaust gas pipe 26 Open / close valves 37, 38, 39 for opening and closing, and open / close valves 40, 41, 42 for communicating with and closing the circulating gas pipe 27. Further, the circulating gas pipe 27 and the exhaust gas pipe 26 are connected via an on-off valve 44. Further, the exhaust gas pipe 26 is connected to the pump 15 via an on-off valve 45. The opening / closing of these on / off valves is controlled by the control unit 19.

  Therefore, in the hydrogen production apparatus 1 of this embodiment, the raw material gas pipe 21, the pump 14, the input gas pipe 24, and the on-off valves 31, 32, and 33 correspond to the supply unit. Moreover, PSA17 corresponds to a purification part. The off gas pipe 23 corresponds to the return portion. Further, the exhaust gas pipe 26, the pump 15, and the on-off valves 37, 38, 39, 45 correspond to a carbon dioxide take-out portion.

(Hydrogen production method: Use only one reforming reaction tube)
Next, a hydrogen production method using only one reforming reaction tube in the hydrogen production apparatus 1 of the present embodiment will be described with reference to FIGS. The hydrogen production method of this embodiment has three steps: (A) reforming step (FIG. 2), (B) regeneration step (FIG. 3), and (C) boosting step (FIG. 4). Here, the case where only the reforming reaction tube 11 is used will be described as a representative, but the same applies to the case where only the other reforming reaction tube 12 or 13 is used. In these drawings, the open / closed valve is shown in black, and the closed open / closed valve is shown in white. In addition, the reforming reaction tubes 12 and 13 and the flow paths and on-off valves 23, 33, 35, 36, 38, 39, 40, 41, 42, and 44 for communicating with them are all shown as omitted illustrations. .

(A) The reforming step is a step of outputting the reformed gas by supplying the source gas to the reforming reaction tube 11 and simultaneously performing the gas reforming reaction and the carbon dioxide absorption reaction inside.
(B) The regeneration step is a step of decompressing the reforming reaction tube 11 to output a carbon dioxide rich gas to regenerate the carbon dioxide absorbent.
(C) The pressure increasing step is a step of increasing the pressure of the reforming reaction tube 11 after the regeneration of the carbon dioxide absorbent to the pressure of the reforming step.

(A) Modification process (Fig. 2)
First, the reforming process will be described. At this time, as shown in FIG. 2, the on-off valves 31 and 34 are opened, and the on-off valves 37 and 45 are closed. As a result, the gas flows indicated by arrows in the figure, and no gas flows through the exhaust gas pipe 26 indicated by broken lines in the figure. That is, the raw material gas is supplied to the reforming reaction tube 11 through the pump 14 and the on-off valve 31. The reformed gas output from the reforming reaction tube 11 is taken out as product hydrogen gas via the output gas tube 25 through the cooling and drying unit 16 and the PSA 17 in order.

  As the raw material gas supplied to the reforming reaction tube 11, for example, a city gas mixed with water vapor and preheated is used. For example, what is necessary is just to mix separately preheated water vapor | steam with the city gas preheated to about 500-600 degreeC. City gas is a gas containing about 88% of methane, and the remainder contains ethane, propane, butane and the like. In this embodiment, the source gas is supplied from the source gas pipe 21. The pump 14 is pressurized to about 0.9 to 1 MPa and supplied to the input gas pipe 24. In general, the gas pressure at the time of supply is generally less than 1 MPa in consideration of restrictions of the high-pressure gas safety method.

Since the reforming reaction tube 11 is filled with a reforming catalyst and a carbon dioxide absorbent (CaO), a steam reforming reaction (see Formula 1) and a carbon monoxide shift reaction (in Formula) 2), carbon dioxide absorption reaction (see Equation 3) occurs in parallel.
CH ₄ + H ₂ O → CO + 3H ₂ (Formula 1)
CO + H ₂ O → CO ₂ + H ₂ (Formula 2)
CaO + CO ₂ → CaCO ₃ (Formula 3)

  Here, the molar fraction of carbon dioxide in the reforming reaction tube 11 in the initial state of the reforming process is about 10% in terms of the average pressure including water vapor. Therefore, if the supply pressure of the input city gas is about 1 MPa, the partial pressure of carbon dioxide in the reforming reaction tube 11 is about 0.1 MPa. Since carbon dioxide is generated by the reforming reaction in the reforming reaction tube 11, the total amount of carbon dioxide increases. However, the carbon dioxide absorption reaction of CaO acts to reduce the partial pressure of carbon dioxide in the gas in the reforming reaction tube 11. As a result, a non-equilibrium state occurs and the reforming reaction proceeds further.

As a result, a reformed gas is obtained in which CO and CO ₂ are 1% or less of the total gas composition, H ₂ is 75% or more, and most of the remaining is CH ₄ . The reformed gas is output via the on-off valve 34 and the output gas pipe 25. Here, the reforming reaction (Formula 1 and Formula 2) is an endothermic reaction, and the CO ₂ absorption reaction by CaO (Formula 3) is an exothermic reaction. Furthermore, the calorific values of these two types of reactions are almost the same. Since these occur simultaneously in the reforming reaction tube 11, no external heating is required at this stage. Therefore, heating by the combustion section 18 is not necessary in this reforming process. The reforming reaction tube 11 is maintained at about 600 ° C. only by supplying an appropriate amount of source gas, and the reforming process proceeds.

  The reformed gas obtained in this manner is sent from the output gas pipe 25 to the cooling and drying unit 16 where the moisture is removed by lowering the temperature. Subsequently, it is thrown into the PSA 17. The PSA 17 contains an adsorbent such as zeolite or activated carbon. By passing this, product hydrogen gas with a purity of 99.99% can be obtained. The adsorption process with the PSA 17 is performed at about 20 ° C. In the simulation of the present inventor, the composition of the reformed gas output from the reforming reaction tube 11 to the output gas tube 25 and the drying gas after passing through the cooling drying unit 16 are as shown in Table 3 below. It was.

  In this (A) reforming step, the source gas may be introduced from one end in the longitudinal direction of the reforming reaction tube 11 and the output gas may be taken out from the other end. In this way, product hydrogen gas can be obtained continuously. Therefore, also in this embodiment, as shown in FIG. 2, a supply system such as the input gas pipe 24 is disposed at one end of the reforming reaction tube 11, and an output system such as the output gas pipe 25 is disposed at the other end. While the gas passes through the reforming reaction tube 11, the size of the reforming reaction tube 11 and the supply amount of the raw material gas are adjusted so that the reforming reaction and the carbon dioxide absorption reaction proceed sufficiently.

(B) Regeneration process (Figure 3)
Next, the regeneration process will be described. If the gas reforming is continued in the reforming reaction tube 11, the reaction of Formula 3 proceeds and the remaining amount of CaO in the reforming reaction tube 11 decreases. Therefore, if a certain amount of carbon dioxide is absorbed, the rate of absorbing more carbon dioxide begins to decrease. This happens when the absorbent breaks through. Therefore, the regeneration process is started shortly before the absorbent breaks through. That is, by reducing the pressure of the reforming reaction tube 11, the carbon dioxide rich gas is taken out from the carbon dioxide absorbent so that carbon dioxide can be absorbed again.

  In the regeneration process, as shown in FIG. 3, the on-off valves 37 and 45 are opened, and the on-off valves 31 and 34 are closed. Further, the pump 14 is stopped. Thereby, the supply of the raw material gas to the reforming reaction tube 11 is stopped, and the reforming reaction is stopped. Therefore, no product hydrogen gas is produced in this process. On the other hand, the pump 15 is driven, and the gas remaining in the reforming reaction tube 11 is discharged through the exhaust gas tube 26. This exhaust gas is a carbon dioxide rich gas containing a large amount of carbon dioxide. Thereby, the inside of the reforming reaction tube 11 is depressurized.

At this time, how the partial pressure of carbon dioxide in the reforming reaction tube 11 changes will be described with reference to FIG. FIG. 5 is a graph with temperature on the horizontal axis and partial pressure of carbon dioxide on the vertical axis. Moreover, what is indicated by a solid line L in the figure is a temperature-pressure equilibrium curve of CaO. That is, in the range above the solid line L in the figure, an absorption reaction mainly represented by the following equation 3 occurs. In the range below the solid line L in the figure, the regeneration reaction of Formula 4 mainly occurs.
CaO + CO ₂ → CaCO ₃ (Formula 3)
CaCO ₃ → CaO + CO ₂ (Formula 4)

In this embodiment, as described above, the reforming step (A) is performed at about 600 ° C., and the partial pressure of carbon dioxide in the normal state during the reforming step is about 10 ⁵ Pa (0.1 MPa). It is. This point is indicated by a double circle (reforming step) in FIG. (A) The internal state of the reforming reaction tube 11 during the reforming step is in the vicinity of this point.

Therefore, in the (B) regeneration step, the reforming reaction tube 11 is decompressed to about 10 ² Pa by the pump 15. The temperature is kept at about 600 ° C. As a result, the partial pressure of carbon dioxide falls below this temperature-pressure equilibrium curve (solid line L), as shown by the dashed arrow p1 in FIG. Therefore, the reaction of Formula 4 releases carbon dioxide and regenerates CaO. This point is indicated by a single circle (regeneration step) in the figure. Here, since the partial pressure of carbon dioxide is about 10%, the reforming reaction tube 11 may be decompressed to about 10 ³ Pa as a whole.

  By continuing the operation of the pump 15 and maintaining the reduced pressure state of the reforming reaction tube 11 for a predetermined time, when a sufficient amount of CaO is regenerated, the regeneration process is terminated. That is, the on-off valves 37 and 45 are closed and the pump 15 is stopped. In addition, this reaction of Formula 4 is an endothermic reaction. Therefore, during the regeneration process, the reforming reaction tube 11 is heated by the combustion unit 18 to maintain the temperature at about 600 ° C. It is preferable that a part of the raw material gas is supplied to the combustion unit 18 and burned.

(C) Boosting process (FIG. 4)
Next, the boosting process will be described. (B) Immediately after the regeneration step is completed, the reforming reaction tube 11 is in a decompressed state as described above, and the partial pressure of carbon dioxide is below the solid line L in FIG. Therefore, CaO cannot absorb carbon dioxide as it is. Therefore, the pressure of the reforming reaction tube 11 is increased at least until it exceeds the solid line L, as indicated by the broken line arrow p2 in FIG. This is the boosting process.

  In this step, as shown in FIG. 4, the on-off valve 31 is opened and the on-off valves 34, 37, 45 are closed. The pump 14 is driven and the pump 15 is stopped. As a result, the pressurized source gas is supplied to the reforming reaction tube 11 to increase the pressure. Since the reforming reaction is incomplete during this pressurization step, the output gas is not taken out. By performing this pressurization step, the reforming reaction tube 11 can absorb carbon dioxide again by the regenerated CaO. When the pressure is increased sufficiently, the pressure increasing process is terminated. After this, it is possible to return to the reforming step (A) and supply the raw material gas to the reforming reaction tube 11 to produce the product hydrogen gas.

In the PSA 17, pressure is reduced as appropriate and part of the product hydrogen gas is introduced to purge the gas trapped in the PSA 17. The off gas discharged by this purge is joined to the source gas pipe 21 via the off gas pipe 23. This is possible because the off-gas composition is mainly CH ₄ and H ₂ and the ratio of CO and CO ₂ is low. In the simulation of the present inventor, the off-gas composition is as shown in Table 4 below. Therefore, this off-gas can be used as a reforming raw material by mixing with the raw material gas. The composition of the gas obtained by mixing the source gas and the off-gas was as shown in Table 5 below. In other words, it was found that there was no problem using it as a raw material gas.

  In the manufacturing method of the present embodiment, the above-mentioned (A) reforming step, (B) regeneration step, and (C) boosting step are repeated in this order, so that the product hydrogen gas can be manufactured by reforming the raw material gas. . At this time, as described above, the internal pressure of the reforming reaction tube 11 is reduced during the (B) regeneration process and increased during the (C) boosting process. On the other hand, the temperature remains at about 600 ° C. For this reason, this method is called a pressure swing method as opposed to a temperature swing method. Since the pressure can be changed in a short time compared with the case where the temperature is changed, the manufacturing method of this embodiment has high time efficiency.

(Hydrogen production method: using three reforming reaction tubes)
Furthermore, in this embodiment, three reforming reaction tubes 11, 12, 13 are provided in order to obtain reformed gas continuously by this pressure swing method. Then, the control unit 19 causes each of the above three steps to be sequentially performed, and also causes a step shifted by one from the other reforming reaction tubes as shown in FIG. That is, in the first mode, the reforming reaction tube 11 performs the reforming process, the reforming reaction tube 12 performs the regeneration process, and the reforming reaction tube 13 performs the pressure increasing process. In the second mode, the reforming reaction tube 11 is caused to perform a regeneration process, the reforming reaction tube 12 is subjected to a boosting process, and the reforming reaction tube 13 is subjected to a reforming process. In the third mode, the reforming reaction tube 11 is caused to perform a boosting step, the reforming reaction tube 12 is subjected to a reforming step, and the reforming reaction tube 13 is subjected to a regeneration step.

  A set of the first mode, the second mode, and the third mode is one cycle, and these are repeated in this order. Thus, the reforming process is performed in the reforming reaction tube 11 in the first mode, the reforming reaction tube 13 in the second mode, and the reforming reaction tube 12 in the third mode. Therefore, product hydrogen gas can be obtained continuously.

  Furthermore, since there are three reforming reaction tubes 11, 12, and 13 as described above, these can be connected to exchange gas with each other. Therefore, in each mode, (D) the first circulation process is performed in the preceding stage, and (E) the second circulation process is performed in the subsequent stage. (D) The first circulation step is left in the reforming reaction tube in the (B) regeneration step from the reforming reaction tube in the (B) regeneration step to the reforming reaction tube in the (C) pressurization step. This is a step of supplying the gas. This is done for a very short time after the start of each mode. The (E) second circulation step is a step of supplying a part of the reformed gas from the reforming reaction tube in the (A) reforming step to the reforming reaction tube in the (C) pressurizing step. is there. This (E) second circulation step is performed during the remaining period of the mode after the completion of the (D) first circulation step.

  As shown in FIG. 6, these are the first circulation step (D-1) performed in the first half of the first mode, the second circulation step (E-1) performed in the second half of the first mode, and the second mode. A first circulation step (D-2) performed in the first half, a second circulation step (E-2) performed in the second half of the second mode, a first circulation step (D-3) performed in the first half of the third mode, It repeats in order of the 2nd circulation process (E-3) performed in the latter half of 3rd mode.

  Here, (D-1) the first circulation process in the first mode is shown in FIG. 7, (E-1) the second circulation process in the first mode is shown in FIG. 8, and (D-2) the first circulation process in the second mode is shown in FIG. The circulation process is shown in FIG. In these figures, the open / close valve being opened is shown in black, and the open / close valve being closed is shown in white. Further, the flow path through which the gas is circulated is indicated by a thick line, and the direction of the flow is indicated by an arrow. A flow path in which no gas is circulated is indicated by a broken line.

(D-1) First Circulation Step in First Mode As shown in FIG. 7, in the first circulation step in (D-1) first mode, the on-off valves 31, 34, 39, 41, and 44 are opened. The other on-off valves are closed. As a result, the reforming step (A) is performed in the reforming reaction tube 11. Further, (B) the reforming reaction tube 12 in the regeneration step and (C) the reforming reaction tube 13 in the pressure increasing step are communicated with each other.

At the start of this mode, the reforming reaction tube 12 is in a state of near breakthrough immediately after completion of the reforming process, and the inside is at a high pressure. In addition, the reformed reaction tube 12 has a slight amount of gas that has undergone the reforming reaction at the reformed gas outlet side (upward in the figure). Therefore, as shown in FIG. 7, when the outlet side of the reforming reaction tube 12 and the inlet side of the reforming reaction tube 13 are connected, the gas remaining in the reforming reaction tube 12 is reformed. To be supplied. As a result, the pressure of the reforming reaction tube 12 can be lowered and the pressure of the reforming reaction tube 13 can be increased. Furthermore, gas components (H ₂ , CH ₄ , CO) other than carbon dioxide in the reforming reaction tube 12 can be recovered in the reforming reaction tube 13.

  At this time, the gas supplied from the reforming reaction tube 12 to the reforming reaction tube 13 is not necessarily completely reformed. Therefore, it is desirable to take a route using the on-off valves 39, 41, and 44 as shown in FIG. However, the on-off valve 41 and the on-off valve 42 may be opened to allow the outlet side of the reforming reaction tube 12 and the outlet side of the reforming reaction tube 13 to communicate with each other. Alternatively, the on-off valve 38 and the on-off valve 39 may be opened to allow the inlet side of the reforming reaction tube 12 and the inlet side of the reforming reaction tube 13 to communicate with each other. In that case, the on-off valve 44 and the flow path of the connected portion may be omitted.

(E-1) Second Circulation Step in First Mode Next to (D-1) step, (E-1) second circulation step in first mode shown in FIG. 8 is executed. At this time, the on-off valves 41, 39, 44 are closed and the on-off valves 36, 38, 45 are opened from the state of the step (D-1). The other on-off valves are not changed from the state of the step (D-1). In this step, (A) the reforming step is performed in the reforming reaction tube 11, and (B) the regeneration step is performed in the reforming reaction tube 12. In the reforming reaction tube 13, (C) the pressure increasing step is performed. Here, a part of the output gas output from the reforming reaction tube 11 is introduced into the reforming reaction tube 13.

  In this way, the pressure can be increased without increasing the amount of carbon dioxide in the reforming reaction tube 13. In this state, since the reforming reaction tube 13 is still at a low pressure, the carbon dioxide absorbent cannot absorb carbon dioxide. Therefore, at this stage, the subsequent reforming process can be performed smoothly by increasing the pressure with a gas that does not contain much carbon dioxide. That is, the time from the start of the reforming process until the reformed gas can be taken out is shorter than when the raw material gas is supplied. Therefore, the reformed gas can be taken out almost continuously even when the mode is switched. This step (E-1) is continuously performed until the reforming reaction tube 11 is close to breakthrough. Although the pressure is increased by introducing a part of the output gas into the reforming reaction tube 13 in the pressure increasing step here, the pressure can be increased using the raw material gas.

(D-2) First Circulation Step in Second Mode When the reforming reaction tube 11 is close to breakthrough, the first circulation step (D-2) performed in the first half of the second mode shown in FIG. Transition. Here, (A) the reforming step is performed in the reforming reaction tube 13 after the (C) pressurizing step. The on-off valves 33, 36, 38, 40, and 44 are opened, and the other on-off valves are all closed. The reforming reaction tube 11 is communicated with the reforming reaction tube 12 through on-off valves 40, 44, and 38. As a result, the gas remaining in the reforming reaction tube 11 is supplied to the reforming reaction tube 12. In this step, from the state of the step (D-1), the reforming reaction tube 11 is changed to the reforming reaction tube 13, the reforming reaction tube 12 is changed to the reforming reaction tube 11, and the reforming reaction tube 13 is changed to the reforming reaction tube. 12 is a state where each is replaced.

  Similarly, the first to third modes are sequentially repeated in the reforming reaction tubes 11, 12, and 13. As a result, the reforming process is continuously performed without interruption in the order of the reforming reaction tube 11, the reforming reaction tube 13, and the reforming reaction tube 12. According to the simulation of the present inventor, the total hydrogen production efficiency in the hydrogen production method according to this embodiment is about 77.2%. From this, it was found that the hydrogen production method of this embodiment is considerably more efficient than the conventional hydrogen production apparatus 100. After the step (E-1) and before the step (D-2), the on-off valve 35 is opened for a short time so that the reformed gas is introduced into the reforming reaction tube 12 after the regeneration step. May be. In this way, the gas with a large amount of carbon dioxide remaining in the reforming reaction tube 12 can be reliably discharged.

  As described above in detail, according to the hydrogen production apparatus of the present embodiment, the reforming reaction tubes 11 to 13 enclose the carbon dioxide absorbent together with the reforming catalyst. The reaction proceeds. Furthermore, since the pressure swing method is used for the regeneration of the carbon dioxide absorbent, the reforming reaction tubes 11 to 13 are not exposed to high temperatures. Therefore, it is not necessary to use a special material for the reforming reaction tubes 11 to 13, and the reforming reaction tubes 11 to 13 can be manufactured at a relatively low cost. Further, since the reforming catalyst, the carbon dioxide absorbent, the reforming reaction tubes 11 to 13 and the like are not subjected to a heat cycle under severe temperature conditions, the durability of the apparatus is excellent. In addition, the pressure switching time can be shortened compared to the temperature switching time. Therefore, since the loss time due to switching can be made extremely small, the reforming reaction tubes 11 to 13 can be simplified.

  Moreover, since it has the some reforming reaction tubes 11-13, while being able to manufacture hydrogen gas continuously, gas components other than the carbon dioxide contained in the reforming reaction tubes 11-13 are collect | recovered in the first half of a regeneration process. be able to. Therefore, the hydrogen production efficiency can be increased. Furthermore, since the carbon dioxide is hardly contained in the off gas from the PSA 17, it can be used by being mixed with the raw material gas. Accordingly, the produced hydrogen gas can be commercialized without waste, and the product hydrogen recovery rate can be increased. As a result, a carbon dioxide absorption / release cycle can be realized by a simple method, contributing to simplification and cost reduction of the device, and to increase the hydrogen production efficiency of the entire system. ing.

"Second form"
Hereinafter, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present embodiment is a hydrogen production apparatus that uses a reforming reaction tube that does not contain a carbon dioxide absorbent and uses a CO converter that contains the carbon dioxide absorbent. The same members as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 10, the hydrogen production apparatus 2 of this embodiment is different from the hydrogen production apparatus 1 of the first embodiment in that one reforming tube is replaced with three reforming reaction tubes 11, 12, and 13. A reaction tube 51 and two CO converters 52 and 53 are provided. In this reforming reaction tube 51, only the reforming catalyst is sealed, and no carbon dioxide absorbent is sealed. A CO conversion catalyst (particles such as iron and copper) and a carbon dioxide absorbent (here, CaO) are enclosed in the CO converters 52 and 53. Then, a CO shift reaction (see Formula 2) for reacting CO with H ₂ O to obtain CO ₂ and H ₂ and a carbon dioxide absorption reaction (see Formula 3) are allowed to proceed together.
CO + H ₂ O → CO ₂ + H ₂ (Formula 2)
CaO + CO ₂ → CaCO ₃ (Formula 3)
In this embodiment, the combustion unit 18 burns the raw material gas and heats only the reforming reaction tube 51.

  Also in the hydrogen production apparatus 2 of the present embodiment, the raw material gas pipe 21, the combustion gas pipe 22, the off gas pipe 23, the input gas pipe 24, the output gas pipe 25, and the like for communicating various gases through the members. An exhaust gas pipe 26 is provided. Further, the output gas pipe 25 is branched into two, a first output gas pipe 61 and a second output gas pipe 62. They communicate with the CO transformers 52 and 53 via the on-off valves 63 and 64, respectively.

  Further, the shift gas pipe 71 output from the CO shifter 52 is branched into a first shift gas pipe 72 and a second shift gas pipe 73, and the cooling and drying unit 16 and the pump are respectively connected via on-off valves 74 and 75. 15 is communicated with. Also, the shift gas pipe 81 output from the CO shifter 53 is branched into a third shift gas pipe 82 and a fourth shift gas pipe 83, and the cooling and drying unit 16 and the pump are respectively connected via on-off valves 84 and 85, respectively. 15 is communicated with.

(Hydrogen production method: Use only one CO transformer)
Next, the hydrogen production method by the hydrogen production apparatus 2 of this embodiment will be described. First, the case where hydrogen is produced using only one CO transformer will be described. In the manufacturing method of this embodiment, (F) the absorption process (FIG. 11) and (G) the regeneration process (FIG. 12) are repeatedly performed in the CO transformer. Here, the case where only the CO transformer 52 is used will be described as a representative, but the same applies to the case where only the CO transformer 53 is used. In these drawings, the open / closed valve is shown in black, and the closed open / closed valve is shown in white. Further, the CO transformer 53 and the flow paths and on-off valves 64, 84, 85 for communicating with them are all omitted.

(F) Absorption process (FIG. 11)
In this step, as shown in FIG. 11, the on-off valves 63 and 74 are opened and the on-off valve 75 is closed. The pump 14 is driven and the pump 15 is stopped. The reforming reaction tube 51 is supplied with raw gas (city gas) and water vapor pressurized by the pump 14 after being preheated. In the reforming reaction tube 51, hydrogen, carbon monoxide, and carbon dioxide are generated from the raw material gas and water vapor by the reforming catalyst.
CH ₄ + H ₂ O → CO + 3H ₂ (Formula 1)
CO + H ₂ O → CO ₂ + H ₂ (Formula 2)
At this time, since the reforming reaction is an endothermic reaction, the reforming reaction tube 51 is heated to about 750 ° C. by the combustion unit 18.

The output gas from the reforming reaction tube 51 is introduced from the output gas tube 25 through the first output gas tube 61 into the CO converter 52. In the CO converter 52, CO ₂ and H ₂ can be obtained by causing the remaining CO to further undergo the reaction of the above formula 2. At this time, since the CO transformer 52 is filled with CaO, CO ₂ is absorbed by the reaction of the following equation (3).
CaO + CO ₂ → CaCO ₃ (Formula 3)

Here, since the CO ₂ is sequentially absorbed generated from CO ₂ and CO transformer 52 included in the output gas, the partial pressure of carbon dioxide in the gas in the CO transformer 52 is decreased. As a result, the carbon monoxide shift reaction becomes non-equilibrium and is further accelerated. Note that the reaction of the above formula 2 and the reaction of the formula 3 are both exothermic reactions. Therefore, this heat may be used for preheating the raw material gas or preheating the combustion air. And it is preferable to hold | maintain the CO transformer 52 at about 400 degreeC.

The gas output from the CO converter 52 is the remaining gas in which the reforming reaction and the CO conversion reaction are finished and the generated carbon dioxide is absorbed by the carbon dioxide absorbent. That is, the reformed gas contains a large amount of hydrogen and hardly contains carbon dioxide. The reformed gas is introduced into the cooling and drying unit 16 through the modified gas pipe 71, the first modified gas pipe 72, and the on-off valve 74. The reformed gas introduced into the cooling and drying unit 16 in this way, for example, CO and CO ₂ are 1% or less of the total gas composition, H ₂ is 75% or more, and most of the remaining is CH ₄ . Thereafter, the product hydrogen gas is obtained by processing in the same manner as the reforming step in the first embodiment. That is, the reformed gas sent to the cooling and drying unit 16 is cooled to remove moisture. Subsequently, the product hydrogen gas having a purity of 99.99% is obtained by being charged into the PSA 17.

(G) Regeneration process (FIG. 12)
As the reaction of Formula 3 proceeds, CaO in the CO transformer 52 decreases. Therefore, shortly before breakthrough, (F) the absorption process is stopped and (G) the regeneration process is started. (G) When the regeneration process is started, the on-off valves 63 and 74 are first closed and the on-off valve 75 is opened. This prevents the output gas from the reforming reaction tube 51 from being input. In the case of an apparatus having only one CO converter, it is desirable to stop the reforming reaction by the reforming reaction tube 51 by stopping the supply of the raw material gas. At the same time as the (G) regeneration step, the off-gas trapped in the PSA 17 may be purged using part of the product hydrogen gas and mixed into the raw material gas.

Then, the inside of the CO converter 52 is connected to the pump 15 from the shift gas pipe 71 through the second shift gas pipe 73, the on-off valve 75, and the exhaust gas pipe 26. Then, the CO converter 52 is depressurized by operating the pump 15, and the carbon dioxide rich gas is taken out from the CO converter 52. Thereby, like the (B) regeneration process in the first embodiment, CaO is regenerated by the reaction of the following formula 4.
CaCO ₃ → CaO + CO ₂ (Formula 4)

  In addition, since reaction of this Formula 4 is an endothermic reaction, it is necessary to heat from the outside. Since it is a CO transformer here, what is necessary is just to hold | maintain at about 400-500 degreeC. Therefore, the CO converter 52 may be heated by using the output gas output to the output gas pipe 25 or the combustion gas discharged from the combustion section 18 and heating the reforming reaction pipe 51. However, if the carbon dioxide absorbent is changed, this temperature is set in consideration of the activation temperature condition.

  At this time, the CO transformer 52 may be heated by the combustion section 18 as shown in FIG. In that case, the CO transformer 52 may be depressurized and heated to about 500-600 ° C. In this way, the regeneration process can be advanced more efficiently. If the temperature rises to such a level, it is not necessary to use a special material for the CO transformer 52, so that the cost is not increased.

(Hydrogen production method: using two CO transformers)
Furthermore, in this embodiment, since the CO transformer 52 and the CO transformer 53 are provided, the (F) absorption process and the (G) regeneration process can be alternately performed. That is, the CO transformer 52 performs the (F) absorption process, the CO transformer 53 performs the (G) regeneration process, and the CO transformer 52 performs the (G) regeneration process. (F) The mode in which the absorption process is performed is repeated alternately.

  Further, the open / close valves 63 and 64 are switched so that the reforming reaction pipe 51 communicates with the CO converter 52 and the CO converter 53 that are performing the (F) absorption step. That is, in the mode in which the CO transformer 52 performs the (F) absorption process, the on-off valves 63, 74, 85 are opened, and the on-off valves 64, 75, 84 are closed. In the mode in which the CO transformer 53 performs the (F) absorption process, the on-off valves 64, 75, 84 are opened, and the on-off valves 63, 74, 85 are closed. Both pumps 14, 15 are activated.

In this way, the reforming reaction tube 51 can continuously perform the reforming reaction. The output gas output to the output gas pipe 25 undergoes CO conversion and CO ₂ absorption by either the CO converter 52 or the CO converter 53 and is sent to the cooling and drying unit 16. Accordingly, product hydrogen gas can be produced continuously. Further, if the CO converter 52 and the CO converter 53 are endothermic reaction on one side and exothermic reaction on the other side and the endothermic reaction side is heated by the heat generated from the exothermic reaction side, the heat can be effectively utilized.

  Further, in this embodiment, a boosting step for boosting the CO transformer may be added. Then, using the three CO transformers, the same rotation as in the first embodiment may be assembled. That is, each of them is made to perform an absorption process, a regeneration process, and a boosting process in order, and a process shifted one by one from other CO transformers. In this way, product gas can be produced more efficiently.

  As explained in detail above, the hydrogen production apparatus 2 of the present embodiment also realizes a carbon dioxide absorption / release cycle by a simple method as in the first embodiment, thereby simplifying and reducing the cost of the apparatus. This is a hydrogen production apparatus that can contribute to the improvement of the hydrogen production efficiency of the entire system.

Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the carbon dioxide absorbent can be depressurized only by opening the on-off valve instead of sucking out by the pump 15. Further, for example, in order to regenerate the carbon dioxide absorbent, carbon dioxide may be further removed from the gas sucked out by the pump 15 with a carbon dioxide absorbent or the like. Then, the remaining gas can be used as a fuel for heating the apparatus or used as part of the raw material gas.
For example, in the above embodiment, CaO is used as the carbon dioxide absorbent, but other absorbents can also be used. In that case, it is recommended to change various conditions according to the characteristics.

It is a schematic block diagram of the hydrogen production apparatus which concerns on a 1st form. It is explanatory drawing which shows the state which is performing the reforming process in the reforming reaction tube. It is explanatory drawing which shows the state which is performing the reproduction | regeneration process in a reforming reaction tube. It is explanatory drawing which shows the state which is performing the pressure | voltage rise process in a reforming reaction tube. It is a graph which shows the change of the partial pressure of the carbon dioxide by a 1st form. It is explanatory drawing which shows the execution procedure of each process in case there are three reforming reaction tubes. It is explanatory drawing which shows the execution procedure (A) of each process in a reforming reaction tube. It is explanatory drawing which shows the execution procedure (B) of each process in a reforming reaction tube. It is explanatory drawing which shows the execution procedure (C) of each process in a reforming reaction tube. It is a schematic block diagram of the hydrogen production apparatus which concerns on a 2nd form. It is explanatory drawing which shows the state in the absorption process in the hydrogen production apparatus which concerns on a 2nd form. It is explanatory drawing which shows the state in the reproduction | regeneration process in the hydrogen production apparatus which concerns on a 2nd form. It is a flowchart which shows schematic structure of the conventional hydrogen production apparatus.

Explanation of symbols

1, 2 Hydrogen production equipment 11, 12, 13, 51 Reforming reaction tube 14, 15 Pump 17 PSA
19 Control part 21 Raw material gas pipe 23 Off-gas pipe 26 Exhaust gas pipe 27 Circulating gas pipe 52, 53 CO transformer

Claims (13)

A reforming reaction tube containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water, and a carbon dioxide absorbent;
A supply unit for supplying a raw material gas to the reforming reaction tube;
A purification unit that separates the reformed gas output from the reforming reaction tube into a product gas having an increased hydrogen concentration and an off-gas having an increased concentration of non-hydrogen components;
A return unit for returning off-gas from the purification unit to the supply unit;
A hydrogen production apparatus comprising: a carbon dioxide extraction unit that extracts carbon dioxide rich gas from the reforming reaction tube by decompressing the reforming reaction tube. The hydrogen production apparatus according to claim 1,
In the reforming reaction tube,
A reforming process for supplying a source gas and outputting a reformed gas;
A regeneration step of decompressing and outputting a carbon dioxide rich gas;
A hydrogen production apparatus comprising a control unit that repeatedly performs a boosting step of boosting in this order. The hydrogen production apparatus according to claim 2,
A hydrogen production apparatus characterized in that the gas supplied to the reforming reaction tube in the pressurization step is a mixed gas of a raw material gas and an off gas. The hydrogen production apparatus according to claim 2,
Having at least three reforming reaction tubes,
The controller is
A first mode in which a reforming step is performed in the first reforming reaction tube, a regeneration step is performed in the second reforming reaction tube, and a pressure increasing step is performed in the third reforming reaction tube;
A second mode for causing the first reforming reaction tube to perform a regeneration step, causing the second reforming reaction tube to perform a boosting step, and causing the third reforming reaction tube to perform a reforming step;
A third mode for causing the first reforming reaction tube to perform a boosting step, causing the second reforming reaction tube to perform a reforming step, and causing the third reforming reaction tube to perform a regeneration step; A hydrogen production apparatus that is repeatedly performed in this order. The hydrogen production apparatus according to claim 4,
A circulation pipe for selectively connecting the three reforming reaction pipes to each other;
The said control part supplies a gas from the reforming reaction tube in a regeneration process to the reforming reaction tube in a pressure | voltage rise process in the front | former stage of each mode. The hydrogen production apparatus according to claim 5,
The control unit supplies a part of the reformed gas from the reforming reaction tube in the reforming process to the reforming reaction tube in the pressurizing process at the subsequent stage of each mode. The hydrogen production apparatus according to claim 6,
The said control part introduce | transduces reformed gas into the reforming reaction tube which completed the reproduction | regeneration process temporarily at the time of mode switching, The hydrogen production apparatus characterized by the above-mentioned. Using a reforming reaction tube that contains a reforming catalyst that promotes the reforming reaction that produces hydrogen from hydrocarbons and water, and a carbon dioxide absorbent,
The reforming reaction tube was fed with raw material gas and water vapor to cause the reforming reaction, and the generated carbon dioxide was absorbed by the carbon dioxide absorbent and the reformed gas was output to increase the hydrogen concentration of the reformed gas. A reforming process to obtain product gas;
A regeneration step of depressurizing the reforming reaction tube after the reforming step to release carbon dioxide from the carbon dioxide absorbent;
A hydrogen production characterized by performing a pressure raising step of supplying a mixed gas of a raw material gas and an off-gas having a higher concentration of the non-hydrogen component of the reformed gas to the reforming reaction tube after the regeneration step to increase the pressure. Method. Using at least three reforming reaction tubes containing a reforming catalyst that promotes a reforming reaction that generates hydrogen from hydrocarbon and water, and a carbon dioxide absorbent.
A first mode in which a reforming step is performed in the first reforming reaction tube, a regeneration step is performed in the second reforming reaction tube, and a pressure increasing step is performed in the third reforming reaction tube;
A second mode for causing the first reforming reaction tube to perform a regeneration step, causing the second reforming reaction tube to perform a boosting step, and causing the third reforming reaction tube to perform a reforming step;
A third mode for causing the first reforming reaction tube to perform a boosting step, causing the second reforming reaction tube to perform a reforming step, and causing the third reforming reaction tube to perform a regeneration step; Repeat in this order,
In the reforming process, a reforming reaction tube is supplied with a raw material gas and water vapor to cause a reforming reaction. The generated carbon dioxide is absorbed by the carbon dioxide absorbent and the reformed gas is output. To obtain product gas with increased hydrogen concentration,
In the regeneration process, the reforming reaction tube after the reforming process is depressurized to release carbon dioxide from the carbon dioxide absorbent,
In the previous stage of the pressurization process, the reforming reaction tube in the regeneration process is supplied with gas and the reforming reaction tube is pressurized,
A hydrogen production method characterized in that, after the pressurizing step, a part of the reformed gas is supplied from the reforming reaction tube in the reforming step to pressurize the reforming reaction tube. A reforming reaction tube containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water;
A converter that is provided downstream of the reforming reaction tube and contains a carbon monoxide shift catalyst that promotes a carbon monoxide shift reaction that generates hydrogen from carbon monoxide and water, and a carbon dioxide absorbent;
A supply unit for supplying a raw material gas to the reforming reaction tube;
A purification unit that separates the reformed gas output from the transformer into a product gas having a high hydrogen concentration and an off-gas having a high concentration of non-hydrogen components;
A return unit for returning off-gas from the purification unit to the supply unit;
A hydrogen production apparatus comprising: a carbon dioxide extraction unit that extracts carbon dioxide rich gas from the transformer by depressurizing the transformer. The hydrogen production apparatus according to claim 10,
An apparatus for producing hydrogen, comprising: a heating section that heats the transformer when the transformer is decompressed by the carbon dioxide take-out section. The hydrogen production apparatus according to claim 10,
Having at least two transformers and a control unit;
The controller is
While performing the reforming reaction in the reforming reaction tube,
The two transformers are configured to alternately perform an absorption process in which carbon dioxide generated by the reforming reaction is absorbed by the carbon dioxide absorbent and a regeneration process in which the carbon dioxide rich gas is released under reduced pressure. To produce hydrogen. Using a reforming reaction tube containing a reforming catalyst for promoting a reforming reaction for generating hydrogen from hydrocarbon and water, and a transformer provided downstream of the reforming reaction tube and containing a carbon dioxide absorbent ,
The reforming reaction tube is supplied with raw material gas and water vapor to perform the reforming reaction, and the reformed gas output from the transformer is increased in the product gas with increased hydrogen concentration and the concentration of non-hydrogen components. Separated into off-gas,
Let the transformer alternately perform an absorption process in which carbon dioxide produced by the reforming reaction is absorbed by the carbon dioxide absorbent and a regeneration process in which the carbon dioxide-rich gas is released under reduced pressure.
A hydrogen production method characterized in that off-gas is returned to the upstream side of the reforming reaction tube when the transformer is in the regeneration step.

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