Syngas production system and method for producing syngas

Abstract

To provide a synthetic gas manufacturing system capable of efficiently manufacturing a synthetic gas having a small content of CO2.SOLUTION: A system for manufacturing a synthetic gas comprising CO and H2 comprises: a reverse shift reaction device for generating gas containing CO by a reverse shift reaction from a raw material gas containing CO2 and H2; a separation device for separating gas generated by the reverse shift reaction device into CO and PSA off gas by a pressure swing adsorption method (PSA method); a merging flow path for merging the PSA off gas separated by the separation device with the raw material gas introduced into the reverse shift reaction device; and a mixing flow path for mixing H2 with the CO separated by the separation device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a synthesis gas production system and a method for producing synthesis gas.

Background Art

[0002] Currently, in the industry, as a countermeasure against climate change due to global warming, research and development on reducing carbon dioxide (CO2) emissions is actively underway to achieve carbon neutrality (CN).

[0003] As a specific method for reducing CO2 emissions, processes and methods for separating and recovering CO2 from waste gas discharged from facilities having CO2 emission sources such as steel mills and thermal power plants have already been studied. So far, research and development have been carried out on various CO2 separation and recovery methods such as adsorption methods, absorption methods, and membrane separation methods.

[0004] However, regarding the utilization of the recovered CO2, at present, there are only limited utilization methods, such as EOR (Enhanced Oil Recovery) in which CO2 is injected into an oil field to increase the crude oil recovery rate in an oil field where the production efficiency has decreased, or an agricultural method in which CO2 is supplied to a greenhouse for increasing crop production.

[0005] Therefore, research and development on CO2 utilization technologies for producing valuable substances such as fuels and chemical raw materials, such as methanol, methane, synthesis gas, etc., by adding hydrogen (H2) to the recovered CO2 or using electric energy, are also actively underway. At this time, by using hydrogen gas produced using renewable energy, it is also possible to reduce the CO2 generated during the production of H2.

[0006] As a method for producing synthesis gas from a mixed gas of CO2 and H2, there is a method of mixing H2 with carbon monoxide (CO) generated by the reverse shift reaction as described below.

[0007] The reverse shift reaction is a chemical reaction represented by the following formula (1), and CO can be produced from a mixed gas of CO2 and H2 by the reverse shift reaction. CO2 + H2 → CO + H2O …(1)

[0008] The reverse shift reaction is an endothermic reaction that proceeds without being affected by pressure. For the reverse shift reaction, for example, a catalyst of the Mn-Pd / Al2O3 system in which an Mn-Pd alloy is supported on Al2O3 can be used, and Patent Document 1 proposes a catalyst that can be used for the reverse shift reaction. By mixing H2 with the CO produced by the reverse shift reaction, synthesis gas, which is a mixed gas mainly composed of CO and H2, can be produced.

[0009] A wide variety of chemical products, such as methanol, gasoline, light oil, dimethyl ether (DME), etc., can be produced from synthesis gas. Methanol can be produced from synthesis gas by the chemical reaction of the following formula (2). CO + 2H2 → CH3OH …(2)

[0010] DME can be produced by indirect synthesis via methanol, or can also be directly produced from synthesis gas by the direct method. In the direct method, DME can be produced by the chemical reaction of the following formula (3) or formula (4). When the H2 / CO ratio of the synthesis gas is 1, the reaction of formula (3) proceeds, accompanied by the generation of CO2. When the H2 / CO ratio of the synthesis gas is 2, the reaction of formula (4) proceeds, and theoretically the generation of CO2 is suppressed. In the actual DME production process, the H2 / CO ratio of the synthesis gas is adjusted to 2 or more. 3CO + 3H2 → CH3OCH3 + CO2…(3) 2CO + 4H2 → CH3OCH3 + H2O …(4)

[0011] In addition, GTL (Gas to liquid) products such as linear hydrocarbons can be produced from synthesis gas by FT (Fischer-Tropsch) synthesis of the following formula (5). Generally, in FT synthesis, the H2 / CO ratio of the synthesis gas is adjusted to 2 - 3. In FT synthesis, olefins, alcohols, etc. are produced as side reaction products. nCO+(2n+1)H2→C n H 2n+2 +nH2O …(5)

[0012] All the chemical reactions represented by the above formulas (2) to (5) are reactions in which the number of molecules decreases, and are high-pressure processes that advantageously proceed under high pressure from the perspective of equilibrium theory. Therefore, pressurization of the synthesis gas is required.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] As described above, technologies for producing synthesis gas from a mixed gas of CO2 and H2 have been developed. In the reverse shift reaction used to produce synthesis gas, it is difficult to completely react CO2 due to reaction constraints, and currently the reaction rate (conversion rate) of CO2 is about 50%. Therefore, unreacted CO2 also remains in the synthesis gas.

[0015] As described above, since the chemical reactions represented by formulas (2) to (5) for generating chemical products from synthesis gas are high-pressure processes, pressurization of the synthesis gas is required. At this time, if unreacted CO2 remains in the synthesis gas, the power required for pressurization increases accordingly, resulting in a problem of reduced energy efficiency.

[0016] The present invention has been made in view of such problems, and an object thereof is to provide a syngas production system capable of efficiently producing syngas with a low CO2 content. Another object is to provide a method for producing such syngas.

Means for Solving the Problems

[0017] As a result of various studies, the present inventors have found that the above object can be achieved by the following invention.

[0018] A syngas production system according to an aspect of the present invention is a syngas production system containing CO and H2, a reverse shift reactor that generates a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation device that separates the gas generated in the reverse shift reactor into CO and PSA off-gas by pressure swing adsorption (PSA method), a confluence channel that confluences the PSA off-gas separated by the separation device into the raw material gas introduced into the reverse shift reactor, and a mixing channel that mixes H2 into the CO separated by the separation device.

[0019] A method for producing syngas according to another aspect of the present invention is a method for producing syngas containing CO and H2, a reverse shift reaction step of generating a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by pressure swing adsorption (PSA method), a confluence step of confluencing the PSA off-gas separated in the separation step into the raw material gas used in the reverse shift reaction step, and a mixing step of mixing H2 into the CO separated in the separation step.

Effects of the Invention

[0020] According to the present invention, it is possible to provide a syngas production system capable of efficiently producing syngas with a low CO2 content. Further, it is possible to provide a method for producing such syngas.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0022] [First Embodiment] Hereinafter, a syngas production system and a method for producing syngas according to a first embodiment of the present invention will be described with reference to the drawings.

[0023] The syngas production system according to the present embodiment is a syngas production system containing carbon monoxide (CO) and hydrogen (H2), and includes a reverse shift reactor that generates a gas containing CO by a reverse shift reaction from a raw material gas containing carbon dioxide (CO2) and H2, a separation device that separates the gas generated in the reverse shift reactor into CO and PSA off-gas by a pressure swing adsorption method (PSA method), a confluence flow path that confluences the PSA off-gas separated by the separation device into the raw material gas introduced into the reverse shift reactor, and a mixing flow path that mixes H2 into the CO separated by the separation device.

[0024] The synthesis gas production method according to this embodiment is a method for producing synthesis gas containing CO and H2, which includes a reverse shift reaction step of generating a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by a pressure swing adsorption method (PSA method), a merging step of merging the PSA off-gas separated in the separation step into the raw material gas supplied to the reverse shift reaction step, and a mixing step of mixing H2 with the CO separated in the separation step.

[0025] <Configuration of Synthesis Gas Production System> FIG. 1 is a block diagram showing an example of a synthesis gas production system according to the first embodiment. The synthesis gas production system 1 shown in FIG. 1 is a synthesis gas production system containing CO and H2, and includes a reverse shift reactor 14, a separation device 20, a merging flow path 22, and a mixing flow path 24.

[0026] The reverse shift reactor 14 is a device that causes a reverse shift reaction represented by the following formula (1) to occur in a raw material gas containing CO2 and H2 and generates a gas containing CO (CO-containing gas). In the reverse shift reactor 14 of this embodiment, the raw material gas is continuously introduced, and the generated CO-containing gas is continuously discharged. Note that instead of a flow-type reverse shift reactor, a batch-type reverse shift reactor may be used. CO2 + H2 → CO + H2O …(1)

[0027] The reverse shift reaction is a reaction (catalytic reaction) whose progress is promoted by a catalyst. In the reverse shift reactor 14, a catalyst suitable for the reverse shift reaction is provided in the flow path of the raw material gas. In this embodiment, as the catalyst provided in the reverse shift reactor 14, those in which Rh, Ba, K, Pt, Ag, Pd, etc. are supported on alumina (Al2O3), those in which Li and Rh are supported on NaY-type zeolite, those in which Pt is supported on titania (TiO2), etc. can be used. The catalyst provided in the reverse shift reactor 14 is preferably one that suppresses the generation of methane as a by-product. In this embodiment, the generation of methane in the reverse shift reactor 14 is not considered.

[0028] Also, the reverse shift reaction is an endothermic reaction and the higher the temperature, the easier it is to proceed. Therefore, a heating device (not shown) for heating the raw material gas is provided in the reverse shift reactor 14. In the reverse shift reactor 14, it is preferable to heat the raw material gas to 400 to 800 °C by the heating device.

[0029] When the reverse shift reaction proceeds for the entire amount of the raw material gas, based on the stoichiometry of formula (1), the H2 / CO2 ratio of the raw material gas becomes 1. However, in the reverse shift reactor 14, it is difficult to cause the reverse shift reaction to proceed for the entire amount of the raw material gas. The CO-containing gas generated in the reverse shift reactor 14 contains unreacted raw material gas in addition to CO and H2O generated by the reverse shift reaction. Therefore, the H2 / CO2 ratio of the raw material gas may be adjusted according to the characteristics of the reverse shift reactor 14 or the catalyst used, to be a value greater than 1 or a value less than 1. The composition and amount of the unreacted raw material gas contained in the CO-containing gas generated in the reverse shift reactor 14 vary depending on the reverse shift reactor 14 used, the catalyst, or the H2 / CO2 ratio of the raw material gas.

[0030] The CO-containing gas discharged from the reverse shift reactor 14 is at a high temperature of 400 to 800 °C, and the H2O contained in the CO-containing gas is contained in the CO-containing gas in a gaseous state, i.e., water vapor.

[0031] The method of introducing the raw material gas into the reverse shift reactor 14 is not particularly limited. For example, as shown in FIG. 1, a raw material gas obtained by mixing CO2 discharged from the CO2 storage unit 11 and H2 discharged from the H2 storage unit 12 can be supplied to the reverse shift reactor 14 through the raw material gas flow path 13.

[0032] The CO₂ storage unit 11 has a container capable of storing CO₂ and a flow rate adjustment unit capable of adjusting the discharge flow rate of CO₂, and can discharge the stored CO₂ gas at an arbitrary flow rate. The method of generating the CO₂ stored in the CO₂ storage unit 11 is not limited, but in this embodiment, in order to reduce the CO₂ discharge amount, it is preferable to use the CO₂ recovered in a facility having a CO₂ generation source such as a steel mill or a thermal power plant. The recovery of CO₂ can be performed by a recovery method such as an adsorption method, an absorption method, or a membrane separation method.

[0033] The H₂ storage unit 12 has a container capable of storing H₂ and a flow rate adjustment unit capable of adjusting the discharge flow rate of H₂, and can discharge the stored H₂ gas at an arbitrary flow rate. Also, regardless of the method of generating the H₂ to be stored, for example, H₂ produced by an electrolytic water hydrogen generator can be used. In this embodiment, in order to reduce the CO₂ discharge amount, it is preferable to use electric power derived from renewable energy such as sunlight or wind power in the electrolytic water hydrogen generator.

[0034] In the raw material gas flow path 13, the CO₂ discharged from the CO₂ storage unit 11 and the H₂ discharged from the H₂ storage unit 12 are mixed, and a raw material gas containing CO₂ and H₂ flows through. The adjustment of the flow rate of the raw material gas and the contents of CO₂ and H₂ in the raw material gas can be performed by adjusting the flow rate of the CO₂ discharged from the CO₂ storage unit 11 and the flow rate of the H₂ discharged from the H₂ storage unit 12.

[0035] The CO-containing gas discharged from the reverse shift reaction device 14 is cooled to room temperature to 80°C and then introduced into the separation device 20. This is because, due to the characteristics of the separation device 20, the CO-containing gas introduced into the separation device 20 must be at room temperature to 80°C. By cooling the CO-containing gas, most of the water vapor contained in the CO-containing gas condenses into water and is separated from the CO-containing gas. Therefore, the cooled CO-containing gas contains the CO obtained by the reverse shift reaction and the unreacted raw material gas.

[0036] The CO-containing gas discharged from the reverse shift reaction device 14 may be naturally cooled in the pipe, but it is preferably cooled by the cooling device 16 as shown in FIG. 1. As the cooling device 16, for example, a shell and tube type or plate stacked type cooling device can be used. As the cooling method, either an air-cooled type or a water-cooled type can be used, but from the viewpoint of efficiency, the water-cooled type is desirable.

[0037] The separation device 20 includes a CO-PSA device 20a that separates the cooled CO-containing gas into CO and PSA off-gas by the PSA method, a PSA off-gas holder 20b that stores the PSA off-gas separated from the CO-containing gas by the CO-PSA device 20a, and a CO induction path 20c that guides the CO separated from the CO-containing gas by the CO-PSA device 20a to the mixing flow path 24. By the separation device 20, the gas containing CO generated in the reverse shift reaction device 14 can be separated into high-purity CO with a low CO2 content and PSA off-gas.

[0038] In the separation device 20 according to the present embodiment, the recovery rate of CO is, for example, about 80%. This is because a part of the CO contained in the CO-containing gas is not adsorbed by the CO adsorbent. The recovery rate of CO varies depending on the adsorbent provided in the CO-PSA device 20a. The recovery rate of CO is the ratio (CO out / CO in ) of the amount of CO (CO in [mol / h] or [Nm 3 / h]) contained in the CO-containing gas introduced into the CO-PSA device 20a to the amount of CO (CO out [mol / h] or [Nm 3 / h]) discharged from the CO-PSA device 20a to the CO induction path 20c. The remainder of the CO that is not discharged to the CO induction path 20c is contained in the PSA off-gas.

[0039] ​​​​A plurality of CO-PSA apparatuses 20a are provided in parallel with respect to the cooling apparatus 16, and in this embodiment, four CO-PSA apparatuses 20a are provided. The CO-PSA apparatus 20a starts operating after the reverse shift reaction is started in the reverse shift reaction apparatus 14 and after the CO-containing gas begins to be discharged from the cooling apparatus 16.

[0040] The CO-PSA apparatus 20a is provided with an adsorbent containing a CO adsorbing substance. The CO adsorbing substance is a substance that selectively adsorbs CO, and the higher the pressure of CO, the greater the amount of CO adsorbed. H2 and CO2 are not adsorbed by the CO adsorbing substance. In this embodiment, as the CO adsorbing substance, for example, a monovalent copper (Cu) supported on alumina (Al2O3) or a polymer porous material can be used.

[0041] The PSA method using the CO-PSA apparatus 20a will be described. The CO-containing gas cooled by the cooling apparatus 16 is introduced into the CO-PSA apparatus 20a in a state pressurized higher than the atmospheric pressure. The pressure of the CO-containing gas introduced into the CO-PSA apparatus 20a at this time can be determined according to the adsorbent and the composition of the CO-containing gas, and 0.2 to 1.0 MPa is preferable.

[0042] Approximately 80% of the CO contained in the CO-containing gas introduced into the CO-PSA apparatus 20a is adsorbed by the CO adsorbing substance. The gas other than CO contained in the CO-containing gas and the CO not adsorbed by the CO adsorbing substance are discharged from the CO-PSA apparatus 20a as PSA off-gas and stored in the PSA off-gas holder 20b. While the pressurized CO-containing gas is being introduced, the CO induction path 20c is closed, and the PSA off-gas does not enter the CO induction path 20c. The introduction time of the pressurized CO-containing gas can be determined according to the capacity of the CO-PSA apparatus 20a, the type and amount of the adsorbent used, and the like.

[0043] When CO is sufficiently adsorbed by the CO adsorbent, the introduction of the CO-containing gas into the CO-PSA apparatus 20a is stopped, and the pressure inside the CO-PSA apparatus 20a is decreased by a vacuum pump provided in the CO-PSA apparatus 20a to desorb CO from the CO adsorbent. Thereby, high-purity CO with a low CO2 content can be obtained. The desorbed CO has, for example, a CO content of 99% by volume or more. The desorbed high-purity CO is discharged into the CO induction path 20c. While the pressure inside the CO-PSA apparatus 20a is being decreased, the PSA off-gas holder 20b is closed, and the desorbed CO does not flow into the PSA off-gas holder 20b. The time for decreasing the pressure inside the CO-PSA apparatus 20a can be determined according to the capacity of the CO-PSA apparatus 20a, the type and amount of the adsorbent used, and the like.

[0044] Thus, according to the PSA method, the cooled CO-containing gas can be separated into PSA off-gas and high-purity CO. Further, by carrying out these operations in cooperation with a plurality of CO-PSA apparatuses 20a and keeping at least one CO-PSA apparatus 20a in a state where the CO-containing gas is being introduced at all times, the separation apparatus 20 can continuously separate the CO-containing gas into PSA off-gas and high-purity CO.

[0045] The PSA off-gas stored in the PSA off-gas holder 20b is introduced into the raw material gas flow path 13 through the confluence flow path 22 and is introduced into the reverse shift reaction apparatus 14 together with the raw material gas. Since the PSA off-gas also contains CO that has not been separated into high-purity CO by the separation apparatus 20, the CO contained in the PSA off-gas can be reused in the separation apparatus 20 without being discharged out of the system by the confluence flow path 22. Therefore, synthesis gas can be efficiently produced.

[0046] The confluence flow path 22 is a pipe provided to connect the PSA off-gas holder 20b of the separation device 20 and the raw material gas flow path 13. A valve 22a (flow rate adjustment device) for adjusting the flow rate of the PSA off-gas is provided in the confluence flow path 22. By the valve 22a, the flow rate of the PSA off-gas introduced into the raw material gas flow path 13 can be adjusted according to the composition and flow rate of the raw material gas, the composition of the PSA off-gas, the processing capacity of the reverse shift reaction device 14, etc. Thereby, the reverse shift reaction can proceed efficiently in the reverse shift reaction device 14. Also, according to the composition and flow rate of the PSA off-gas, the flow rate of CO2 discharged from the CO2 storage unit 11 and the flow rate of H2 discharged from the H2 storage unit 12 may be adjusted.

[0047] On the other hand, the high-purity CO discharged into the CO induction path 20c is mixed with the H2 supplied from the H2 storage unit 12 in the mixing flow path 24. Thereby, according to the synthesis gas manufacturing system according to the present embodiment, a synthesis gas with a low CO2 content can be manufactured.

[0048] The mixing flow path 24 is a pipe connecting the CO induction path 20c of the separation device 20 and the pipe 12a through which the H2 discharged from the H2 storage unit 12 flows. By adjusting the flow rate of the H2 supplied from the H2 storage unit 12 to the mixing flow path 24 according to the flow rate of the CO supplied to the mixing flow path 24, a synthesis gas with an arbitrary composition (H2 / CO ratio) according to the application can be obtained. The obtained synthesis gas is sent to the subsequent process according to the application. The H2 supplied to the mixing flow path 24 may be supplied from an H2 source other than the H2 storage unit 12.

[0049] <Manufacturing method of synthesis gas> The synthesis gas production method according to this embodiment is a method for producing synthesis gas containing CO and H2, and includes a reverse shift reaction step of generating a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by a pressure swing adsorption method (PSA method), a merging step of merging the PSA off-gas separated in the separation step into the raw material gas supplied to the reverse shift reaction step, and a mixing step of mixing H2 into the CO separated in the separation step.

[0050] The synthesis gas production method according to this embodiment is a method for producing synthesis gas containing CO and H2, and can be implemented, for example, by the synthesis gas production system 10 shown in FIG. 1.

[0051] The synthesis gas production method according to this embodiment includes a reverse shift reaction step, a separation step, a merging step, and a mixing step.

[0052] The reverse shift reaction step is a step of generating a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, and in the synthesis gas production system shown in FIG. 1, it is carried out in the reverse shift reaction apparatus 14.

[0053] The separation step is a step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by the PSA method, and in the synthesis gas production system shown in FIG. 1, it is carried out in the separation apparatus 20.

[0054] The merging step is a step of merging the PSA off-gas separated in the separation step into the raw material gas supplied to the reverse shift reaction step, and in the synthesis gas production system shown in FIG. 1, it is carried out by merging the PSA off-gas from the merging flow path 22 into the raw material gas flowing through the raw material gas flow path 13.

[0055] The mixing process is a process of mixing H2 with the CO separated in the separation process. In the syngas production system shown in FIG. 1, the CO separated from the CO-containing gas by the separation device 20 and discharged to the CO induction path 20c is mixed with the H2 supplied from the H2 storage unit 12 in the mixing flow path 24.

[0056] [Second Embodiment] Next, a second embodiment of the present invention will be described.

[0057] FIG. 2 is a block diagram showing an example of a syngas production system according to the second embodiment. The syngas production system 30 according to the present embodiment has the same configuration as the syngas production system according to the first embodiment, except that it has a discharge flow path 31 for discharging a part of the PSA off-gas separated by the separation device 20 outside the syngas production system 30. The same reference numerals are given and the description is omitted.

[0058] The discharge flow path 31 is branched from the confluence flow path 22 for introducing the PSA off-gas from the PSA off-gas holder 20b into the raw material gas flow path 13. An openable and closable valve 31a is provided in the discharge flow path 31.

[0059] In the reverse shift reactor 14, methane (CH4) may be generated as a by-product of the reverse shift reaction depending on the catalyst used. In the first embodiment, the generation of CH4 in the reverse shift reactor 14 was not considered, but in the second embodiment, the generation of CH4 in the reverse shift reactor 14 is considered.

[0060] When CH4 is generated in the reverse shift reactor 14, the PSA off-gas contains CH4. If the PSA off-gas containing CH4 is continuously introduced into the reverse shift reactor 14 together with the raw material gas, the CH4 content of the PSA off-gas will gradually increase. Since CH4 is an impurity that does not contribute to the reverse shift reaction, in order to efficiently advance the reverse shift reaction and efficiently obtain CO, which is the target component in this reaction, it is preferable that the CH4 content of the PSA off-gas is as low as possible.

[0061] In this embodiment, by discharging the PSA off-gas from the discharge channel 31 to the outside of the syngas production system 30, it is possible to suppress an excessive increase in the CH4 content of the PSA off-gas. The discharge of the PSA off-gas can be carried out when a predetermined condition that is assumed to have an adverse effect on the CO production efficiency of the reverse shift reactor 14 is satisfied, such as when the syngas production system 30 has been operated for a predetermined time, when a predetermined amount of syngas has been produced in the syngas production system 30, or when the CH4 content of the PSA off-gas introduced into the PSA off-gas holder 20b or discharged from the PSA off-gas holder 20b has reached a predetermined value or more. Also, even when the predetermined condition is not satisfied, the PSA off-gas may be discharged at an arbitrary timing. The CH4 content of the PSA off-gas can be measured, for example, by a sensor provided in the flow path of the PSA off-gas.

[0062] The PSA off-gas discharged from the discharge channel 31 contains H2 and CH4 and has heat quantity, so it may be used as fuel as it is. Also, since the PSA off-gas discharged from the discharge channel 31 contains CO2, it may be introduced into a recovery device (CO2 recovery device) for recovering the CO2 stored in the CO2 storage unit 11 and separated into CO2 and H2 and CH4 having heat quantity. The CO2 recovered by the CO2 recovery device can be stored in the CO2 storage unit 11 and used as a raw material gas, and the separated H2 and CH4 can be used as fuel.

[0063] [Modification Example] In the above first and second embodiments, the PSA off-gas holder 20b for storing the PSA off-gas separated by the CO-PSA device 20a is provided in the separation device 20, and the valve 22a is provided in the confluence channel 22. However, both or one of the PSA off-gas holder 20b and the valve 22a may not be provided. However, in order to facilitate the adjustment of the supply amount of the PSA off-gas to the reverse shift reactor 14, it is preferable to provide the PSA off-gas holder 20b and the valve 22a.

[0064] [Summary of the Disclosed Technology] This specification discloses technologies in various aspects as described above. Among them, the main technologies are summarized below.

[0065] As described above, a synthesis gas production system according to an aspect of the present invention is a synthesis gas production system containing CO and H2, and includes a reverse shift reactor that generates a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation device that separates the gas generated in the reverse shift reactor into CO and PSA off-gas by a pressure swing adsorption method (PSA method), a merging flow path that merges the PSA off-gas separated by the separation device into the raw material gas introduced into the reverse shift reactor, and a mixing flow path that mixes H2 with the CO separated by the separation device.

[0066] According to this configuration, synthesis gas with a low CO2 content can be efficiently produced.

[0067] In the synthesis gas production system having the above configuration, the merging flow path may have a flow rate adjustment device for adjusting the flow rate of the PSA off-gas merged into the raw material gas.

[0068] According to this configuration, the flow rate of the PSA off-gas merged into the raw material gas can be adjusted, and the reverse shift reaction can proceed efficiently in the reverse shift reactor. Therefore, synthesis gas with a low CO2 content can be produced more efficiently.

[0069] The synthesis gas production system having the above configuration may have a discharge flow path for discharging a part of the PSA off-gas separated by the separation device outside the synthesis gas production system.

[0070] According to this configuration, when CH4 is generated as a by-product of the reverse shift reaction in the reverse shift reaction apparatus, the PSA off-gas can be appropriately discharged outside the synthesis gas production system through the discharge channel. Therefore, it is possible to suppress the excessive increase in the CH4 content contained in the PSA off-gas. As a result, the reverse shift reaction can proceed efficiently in the reverse shift reaction apparatus, and synthesis gas with a low CO2 content can be produced more efficiently.

[0071] Also, as described above, the method for producing synthesis gas according to another aspect of the present invention is a method for producing synthesis gas containing O and H2, including a reverse shift reaction step of generating a gas containing CO from a raw material gas containing CO2 and H2 by a reverse shift reaction, a separation step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by a pressure swing adsorption method (PSA method), a merging step of merging the PSA off-gas separated in the separation step into the raw material gas supplied to the reverse shift reaction step, and a mixing step of mixing H2 with the CO separated in the separation step.

[0072] According to this configuration, synthesis gas with a low CO2 content can be efficiently produced.

Explanation of symbols

[0073] 10, 30 Synthesis gas production system 14 Reverse shift reaction apparatus 20 Separation apparatus 22 Merging channel 22a Valve (flow rate adjustment device) 24 Mixing channel 31 Discharge channel

Claims

1. CO and H ２ A synthesis gas production system containing CO ２ and H ２ A reverse shift reactor that generates a gas containing CO from a raw material gas containing CO and H by a reverse shift reaction a separation device that separates the gas generated by the reverse shift reaction device into CO and PSA off-gas by pressure swing adsorption (PSA method); a merging flow path that merges the PSA off-gas separated by the separation device into the raw material gas introduced into the reverse shift reaction device; A mixing flow path for mixing H with the CO separated by the separation device is provided, ２ and. the separation device has an adsorbent containing a CO adsorbing substance in which monovalent copper is supported on alumina or a polymer porous material; the merging flow path has a PSA off-gas holder that houses the PSA off-gas, and a flow rate adjusting device provided in the merging flow path downstream of the PSA off-gas holder to adjust the flow rate of the PSA off-gas to be merged into the raw material gas, a synthetic gas production system.

2. The synthetic gas production system according to claim 1, further comprising a discharge flow path for discharging a part of the PSA off-gas separated by the separation device outside the synthetic gas production system.

3. CO and H ２ A method for producing synthesis gas containing CO ２ and H ２ a reverse shift reaction step of generating a gas containing CO from a raw material gas containing CO and H by a reverse shift reaction; a separation step of separating the gas generated in the reverse shift reaction step into CO and PSA off-gas by pressure swing adsorption (PSA method); a merging step of housing the PSA off-gas separated in the separation step in a PSA off-gas holder, and then adjusting the supply amount and merging it into the raw material gas supplied to the reverse shift reaction step; A mixing step of mixing H with the CO separated in the separation step is provided, ２ and the separation step includes adsorption of CO by an adsorbent containing a CO adsorbing substance in which monovalent copper is supported on alumina or a polymer porous material, a synthetic gas production method.

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