Liquid fuel synthesis system and liquid fuel synthesis method

Abstract

A liquid fuel synthesis system (100) comprises a liquid fuel synthesis unit (110) and a sweep gas supply unit (120). The liquid fuel synthesis unit (110) allows permeation of water vapor, which is one product in a reaction for converting a source gas containing at least hydrogen and carbon dioxide into a liquid fuel. The sweep gas supply unit (120) supplies the liquid fuel synthesis unit (110) with a sweep gas for sweeping the water vapor that has permeated through a separation membrane (112). The sweep gas contains hydrogen or carbon dioxide as main components.

Description

Technical Field

[0001] The present invention relates to a liquid fuel synthesis system and a liquid fuel synthesis method.

Background Art

[0002] In recent years, in a conversion reaction from a raw material gas containing hydrogen and carbon dioxide to a liquid fuel such as methanol or ethanol (specifically, a fuel in a liquid state under normal temperature and pressure), a liquid fuel synthesis system capable of improving the conversion efficiency by separating water vapor, which is a by-product, has been developed.

[0003] Patent Document 1 discloses a liquid fuel synthesis system including a membrane reactor, a raw material gas supply unit, and a sweep gas supply unit. The membrane reactor includes a catalyst that promotes a conversion reaction from a raw material gas containing hydrogen and carbon dioxide to methanol, and a separation membrane that allows water vapor, which is a by-product of the conversion reaction, to permeate. The raw material gas supply unit supplies the raw material gas to the non-permeation side of the separation membrane. The sweep gas supply unit supplies the sweep gas to the permeation side of the separation membrane. The water vapor that has permeated through the separation membrane is discharged from the membrane reactor together with the sweep gas.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, since the molecular diameters of water and hydrogen are close to each other, a part of the hydrogen contained in the raw material gas easily passes through the separation membrane and mixes into the sweep gas. If the hydrogen mixed into the sweep gas can be reused, the utilization rate of the raw material gas can be improved.

[0006] However, in the liquid fuel synthesis system described in Patent Document 1, at least one of nitrogen and air is used as the sweep gas, so in order to reuse the hydrogen mixed in the sweep gas, it is necessary to separate the hydrogen individually, which is complicated.

[0007] This invention has been made in view of the above circumstances, and aims to provide a liquid fuel synthesis system and a liquid fuel synthesis method that can improve the utilization rate of raw material gas. [Means for solving the problem]

[0008] A liquid fuel synthesis system according to a first aspect of the present invention comprises a liquid fuel synthesis unit and a sweep gas supply unit. The liquid fuel synthesis unit permeates the products of the conversion reaction from a raw material gas containing at least hydrogen and carbon dioxide to a liquid fuel. The sweep gas supply unit supplies a sweep gas to the liquid fuel synthesis unit for sweeping the products that have permeated through the separation membrane. The sweep gas mainly contains hydrogen or carbon dioxide.

[0009] A liquid fuel synthesis system according to a second aspect of the present invention relates to the first aspect described above, wherein the swept gas mainly contains hydrogen.

[0010] A liquid fuel synthesis system according to a third aspect of the present invention relates to the second aspect described above, wherein the swept gas contains carbon dioxide as a by-component.

[0011] A liquid fuel synthesis system according to a fourth aspect of the present invention relates to any of the first to third aspects described above and includes a moisture removal unit that removes moisture from exhaust gas discharged from the liquid fuel synthesis unit and containing sweep gas and products.

[0012] A liquid fuel synthesis system according to a fifth aspect of the present invention relates to the fourth aspect described above, and the water removal unit includes a heat exchanger that uses a source gas containing at least hydrogen and carbon dioxide as a refrigerant.

[0013] A liquid fuel synthesis system according to the sixth aspect of the present invention relates to the fifth aspect and includes a pressure boosting unit that increases the pressure of a mixed gas of a material gas that has passed through a moisture removal unit and a sweeping gas, and supplies it to the liquid fuel synthesis unit.

[0014] A liquid fuel synthesis method according to a seventh aspect of the present invention comprises a step of supplying a sweeping gas to the permeable side of a separation membrane to sweep away products generated by the conversion reaction and permeating the separation membrane, while a raw material gas containing at least hydrogen and carbon dioxide is supplied to the non-permeable side of the separation membrane to allow the conversion reaction from the raw material gas to liquid fuel to proceed. The sweeping gas mainly contains hydrogen or carbon dioxide.

[0015] A liquid fuel synthesis method according to the eighth aspect of the present invention relates to the seventh aspect described above and further comprises a step of removing water from exhaust gas containing a sweep gas and a product.

[0016] A liquid fuel synthesis method according to the ninth aspect of the present invention relates to the eighth aspect described above, and in the step of removing water from exhaust gas, a source gas containing at least hydrogen and carbon dioxide is used as a refrigerant.

[0017] A liquid fuel synthesis method according to the tenth aspect of the present invention relates to the ninth aspect described above and further comprises a step of increasing the pressure of a mixed gas of a source gas and a sweep gas after it has been used as a refrigerant. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a liquid fuel synthesis system and a liquid fuel synthesis method that can improve the utilization rate of raw material gas. [Brief explanation of the drawing]

[0019] [Figure 1] Schematic diagram showing the configuration of a liquid fuel synthesis system according to the embodiment. [Figure 2] Schematic diagram showing the configuration of the liquid fuel synthesis system according to Modification 2. [Figure 3] Schematic diagram showing the configuration of the liquid fuel synthesis system according to Modification 5. [Figure 4] Schematic diagram showing the configuration of the liquid fuel synthesis system according to Modification 5 [Figure 5] Schematic diagram showing the configuration of the liquid fuel synthesis system according to Modification 5 [Figure 6] Schematic diagram showing the configuration of the liquid fuel synthesis system according to Modification 5

Mode for Carrying Out the Invention

[0020] Next, embodiments of the present invention will be described with reference to the drawings. However, the drawings are schematic, and the ratios of each dimension etc. may be different from the actual ones.

[0021] (Liquid fuel synthesis system) FIG. 1 is a schematic diagram showing the configuration of a liquid fuel synthesis system 100. The liquid fuel synthesis system 100 includes a liquid fuel synthesis unit 110, a sweep gas supply unit 120, a raw material gas supply unit 130, and a first drain trap 140.

[0022] The liquid fuel synthesis unit 110 is a so-called membrane reactor for converting raw material gas into liquid fuel. The shape of the liquid fuel synthesis unit 110 is not particularly limited, and for example, it can be a monolith shape, a flat plate shape, a tubular shape, a cylindrical shape, a columnar shape, a polygonal columnar shape, etc. The monolith shape means a shape having a plurality of cells penetrating in the longitudinal direction, and is a concept including the honeycomb shape.

[0023] The raw material gas is supplied from the raw material gas supply unit 130 to the liquid fuel synthesis unit 110. The raw material gas contains at least hydrogen and carbon dioxide. The raw material gas may contain carbon monoxide. The raw material gas may be so-called synthesis gas (Syngas). The liquid fuel is a fuel in a liquid state at normal temperature and normal pressure, or a fuel that can be liquefied at normal temperature and increased pressure. As the fuel in a liquid state at normal temperature and normal pressure, for example, methanol, ethanol, C n H 2(m-2n)Examples include liquid fuels represented by (m being an integer less than 90, and n being an integer less than 30), and mixtures thereof. Examples of fuels that can be liquefied at room temperature and under pressure include propane, butane, and mixtures thereof.

[0024] For example, the reaction equation (1) for synthesizing methanol by catalytic hydrogenation of a raw material gas containing carbon dioxide and hydrogen in the presence of a catalyst is as follows:

[0025] CO2 + 3H2 ⇔ CH3OH + H2O (1)

[0026] The above reaction is an equilibrium reaction, and to increase both the conversion rate and the reaction rate, it is preferable to carry out the reaction under high temperature and high pressure (for example, 180°C or higher, 2 MPa or higher). The liquid fuel is in a gaseous state at the time of synthesis and remains in a gaseous state at least until it flows out of the liquid fuel synthesis unit 110. The liquid fuel synthesis unit 110 preferably has heat resistance and pressure resistance suitable for the synthesis conditions of the desired liquid fuel.

[0027] The liquid fuel synthesis unit 110 according to this embodiment includes a catalyst layer 111, a separation membrane 112, a non-permeable space 110A, and a permeable space 110B.

[0028] The catalyst layer 111 is placed in the impermeable space 110A. In the catalyst layer 111, the conversion reaction from the raw material gas to liquid fuel proceeds.

[0029] The catalyst layer 111 is a porous body composed of a porous material and a catalyst. The average pore diameter of the catalyst layer 111 can be between 5 μm and 25 μm. The average pore diameter of the catalyst layer 111 can be measured by the mercury intrusion method. The porosity of the catalyst layer 111 can be between 25% and 50%. The average particle size of the porous material constituting the catalyst layer 111 can be between 1 μm and 100 μm. In this embodiment, the average particle size is the arithmetic mean of the maximum diameters of 30 target particles (randomly selected) measured by cross-sectional microstructure observation using a Scanning Electron Microscope (SEM).

[0030] As porous materials, ceramic materials, metal materials, resin materials, etc., can be used, with ceramic materials being particularly preferred. As aggregates for ceramic materials, alumina (Al2O3), titania (TiO2), mullite (Al2O3·SiO2), celben, and cordierite (Mg2Al4Si5O 18 Materials such as ) can be used, and alumina is preferred considering availability, soil stability, and corrosion resistance. As an inorganic binder for the ceramic material, at least one of titania, mullite, easily sintered alumina, silica, glass frit, clay minerals, and easily sintered cordierite can be used. However, the ceramic material does not need to contain an inorganic binder.

[0031] The catalyst facilitates the conversion reaction from the source gas to the liquid fuel. The catalyst is placed within the pores of a porous material. The catalyst may be supported on the inner surface of the pores, or a support for the catalyst may be attached to the inner surface of the pores.

[0032] Any known catalyst suitable for the conversion reaction to the desired liquid fuel can be used. Specifically, metal catalysts (such as copper and palladium), oxide catalysts (such as zinc oxide, zirconia, and gallium oxide), and catalysts combining these (such as copper-zinc oxide, copper-zinc oxide-alumina, copper-zinc oxide-chromium oxide-alumina, copper-cobalt-titania, and catalysts modified with palladium) can be used.

[0033] The separation membrane 112 allows water vapor, one of the products of the conversion reaction from the raw material gas to liquid fuel, to pass through. This allows the reaction equilibrium in equation (1) to be shifted towards the product side by utilizing the equilibrium shift effect.

[0034] The molecular diameter of water (0.26 nm) is close to that of hydrogen (0.296 nm). Therefore, in this embodiment, it is assumed that not only water vapor, which is a product of the conversion reaction, but also some of the hydrogen contained in the raw material gas will permeate through the separation membrane 112.

[0035] The separation membrane 112 has a density of 100 nmol / (s·Pa·m). 2 It is preferable to have a water vapor permeability coefficient of ) or higher. The water vapor permeability coefficient can be determined by known methods (see Ind.Eng.Chem.Res.,40,163-175(2001)).

[0036] The separation membrane 112 preferably has a separation coefficient of 100 or more. The larger the separation coefficient, the easier it is for water vapor to permeate, and the less likely it is for components other than water vapor (such as hydrogen, carbon dioxide, and liquid fuels) to permeate. The separation coefficient can be determined by a known method (see Fig. 1 in "Separation and Purification Technology 239 (2020) 116533").

[0037] An inorganic membrane can be used as the separation membrane 112. Inorganic membranes are preferred because they have heat resistance, pressure resistance, and water vapor resistance. Examples of inorganic membranes include zeolite membranes, silica membranes, alumina membranes, and composite membranes thereof. For example, an LTA-type zeolite membrane in which the molar ratio of silicon element (Si) to aluminum element (Al) (Si / Al) is 1.0 or more and 3.0 or less is preferred because it has excellent water vapor permeability.

[0038] The separation membrane 112 may also be supported by a porous substrate.

[0039] The impermeable space 110A is the space on the impermeable side of the separation membrane 112. Raw material gas is supplied to the impermeable space 110A from the raw material gas supply unit 130. The raw material gas flows into the impermeable space 110A through the inlet a1. The liquid fuel synthesized in the catalyst layer 111 flows out of the impermeable space 110A through the outlet a2. The liquid fuel flowing out from the outlet a2 may contain unreacted residual raw material gas. The residual raw material gas mixed with the liquid fuel is separated from the liquid fuel in the first drain trap 140. The separated residual raw material gas is returned to the raw material gas supply unit 130 (specifically, the second booster pump 133b, which will be described later). The residual raw material gas contains at least one of hydrogen and carbon dioxide.

[0040] The permeate-side space 110B is the space on the permeate side of the separation membrane 112. Water vapor and hydrogen that have permeated through the separation membrane 112 flow into the permeate-side space 110B. In addition, sweep gas is supplied to the permeate-side space 110B from the sweep gas supply unit 120. The sweep gas flows into the permeate-side space 110B through the inlet b1. The exhaust gas containing the sweep gas and water vapor flows out of the permeate-side space 110B through the outlet b2.

[0041] The sweep gas supply unit 120 is located upstream of the permeate space 110B. The sweep gas supply unit 120 includes a storage unit 121, a flow rate adjustment mechanism 122, and a heating unit 123.

[0042] The storage section 121 stores the sweep gas. The sweep gas mainly contains hydrogen or carbon dioxide. In this way, because the sweep gas mainly contains hydrogen or carbon dioxide, the hydrogen that permeates through the separation membrane 112 can be reused as part of the raw material gas without being separated from the sweep gas. As a result, the utilization rate of the raw material gas can be easily improved. Note that "mainly containing hydrogen or carbon dioxide" means that hydrogen or carbon dioxide has the highest content among the gases contained in the sweep gas.

[0043] The sweeping gas may contain only hydrogen and carbon dioxide, or it may contain both hydrogen and carbon dioxide. When the sweeping gas contains both hydrogen and carbon dioxide, the specific heat of the sweeping gas can be increased compared to when the sweeping gas contains only hydrogen and carbon dioxide, thereby improving the efficiency of heat removal associated with the synthesis of liquid fuels.

[0044] The sweep gas preferably contains hydrogen as its main component. This reduces the difference between the partial pressure of hydrogen in the non-permeable space 110A and the partial pressure of hydrogen in the permeable space 110B, thereby suppressing the amount of hydrogen that permeates through the separation membrane 112. The hydrogen content in the water sweep gas is not particularly limited, but for example, it can be 60 mol% or more and 100 mol% or less.

[0045] The sweep gas preferably contains carbon dioxide as a secondary component. This prevents the ratio of exhaust gas volume to moisture content in the exhaust gas from becoming excessively small, which would lower the dew point (i.e., humidity) of the exhaust gas. As a result, the load on the heat exchanger 132a, described later, can be reduced. Containing carbon dioxide as a secondary component means that the carbon dioxide content is the second highest among the gases contained in the sweep gas, after hydrogen. The carbon dioxide content in the sweep gas is not particularly limited, but for example, it can be between 5 mol% and 40 mol%.

[0046] The flow rate adjustment mechanism 122 adjusts the flow rate of the sweep gas supplied from the storage section 121. A pump or blower can be used as the flow rate adjustment mechanism 122. However, if the sweep gas is stored in the storage section 121 under pressurization, the flow rate adjustment mechanism 122 can be omitted.

[0047] The heating unit 123 heats the swept gas to a desired temperature. The heating unit 123 is not particularly limited as long as it is capable of heating the swept gas. The heating unit 123 may also be heated using a regenerative heat exchanger that utilizes heat exchange with the heat exchanger 132a, which will be described later.

[0048] The raw material gas supply unit 130 is located downstream of the impermeable space 110A. The raw material gas supply unit 130 includes a raw material gas source 131, a moisture removal unit 132, and a pressure boosting unit 133.

[0049] The material gas source 131 stores the material gas. The material gas contains at least hydrogen and carbon dioxide. The material gas may also contain carbon monoxide. The material gas may be so-called synthesis gas. The material gas stored in the material gas source 131 is supplied to the moisture removal unit 132.

[0050] The moisture removal unit 132 removes moisture from the exhaust gas discharged from the liquid fuel synthesis unit, which contains swept gas and water vapor. This separates the swept gas from the exhaust gas. The moisture removal unit 132 includes a heat exchanger 132a and a second drain trap 132b.

[0051] The heat exchanger 132a has a first flow path c1 through which the material gas supplied from the material gas source 131 flows, and a second flow path c2 through which the exhaust gas discharged from the liquid fuel synthesis unit 110 flows. The heat exchanger 132a uses the material gas as a refrigerant to condense the water vapor in the exhaust gas into water. This allows for simultaneous heating of the material gas and cooling of the exhaust gas, thereby improving the thermal efficiency of the liquid fuel synthesis system 100.

[0052] The second drain trap 132b is located downstream of the heat exchanger 132a. The second drain trap 132b separates the water condensed in the heat exchanger 132a from the sweep gas. The sweep gas separated by the second drain trap 132b is mixed with the material gas that has passed through the heat exchanger 132a downstream of the second drain trap 132b. This generates a mixed gas of the sweep gas and the material gas.

[0053] The mixed gas is supplied to the pressure boosting unit 133. The pressure boosting unit 133 is located downstream of the second drain trap 132b and upstream of the liquid fuel synthesis unit 110. The pressure boosting unit 133 increases the pressure of the material gas and sweep gas that have passed through the moisture removal unit 132 and supplies them to the liquid fuel synthesis unit 110. The pressure boosting unit 133 includes a first booster pump 133a and a second booster pump 133b.

[0054] The first booster pump 133a pressurizes the mixed gas to a predetermined first pressure. The mixed gas pressurized by the first booster pump 133a is mixed with the residual raw material gas separated from the liquid fuel in the first drain trap 140. This generates a raw material gas which is a mixture of the mixed gas and the residual raw material gas.

[0055] The second booster pump 133b increases the pressure of the raw material gas to a predetermined second pressure. The second pressure is suitable for the conversion reaction from the raw material gas to liquid fuel and is higher than the first pressure. The raw material gas, pressurized by the second booster pump 133b, is supplied to the impermeable space 110A of the liquid fuel synthesis unit 110.

[0056] (Liquid fuel synthesis method) Next, a liquid fuel synthesis method using the liquid fuel synthesis system 100 will be described.

[0057] The liquid fuel synthesis method comprises a step of supplying a raw material gas to the non-permeable side of a separation membrane 112, and supplying a sweep gas mainly containing hydrogen or carbon dioxide to the permeable side of the separation membrane 112. On the non-permeable side of the separation membrane 112, the conversion reaction from the raw material gas to liquid fuel proceeds. On the permeable side of the separation membrane 112, water vapor that permeates through the separation membrane 112 is incorporated into the sweep gas.

[0058] The liquid fuel synthesis method further comprises a step of removing moisture from the sweep gas and exhaust gas containing water vapor. In this embodiment, the source gas is used as a refrigerant in this step. This allows for simultaneous heating of the source gas and cooling of the exhaust gas, thereby improving the thermal efficiency of the liquid fuel synthesis system 100.

[0059] The liquid fuel synthesis method further comprises a step of increasing the pressure of a mixed gas of the source gas and sweep gas after it has been used as a refrigerant. In this step, it is preferable to generate the source gas by mixing the residual source gas separated from the liquid fuel into the mixed gas. This makes it possible to improve the utilization efficiency of the source gas.

[0060] (Modified version of the embodiment) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0061] (Variation 1) In the above embodiment, the catalyst layer 111 is arranged on the separation membrane 112, but the embodiment is not limited to this. For example, the impermeable space 110A may be filled with particulate catalyst. The particle size (diameter) of the particulate catalyst is not particularly limited, but it can be, for example, 0.5 mm or more and 10 mm or less.

[0062] (Modification 2) In the above embodiment, the liquid fuel synthesis system 100 includes a liquid fuel synthesis unit 110 which is a membrane reactor, but it is not limited to this.

[0063] For example, the liquid fuel synthesis system 100 may include a liquid fuel synthesis unit 160 having a catalyst unit 161 and a separation unit 162, as shown in Figure 2.

[0064] The catalyst unit 161 is supplied with raw material gas from the raw material gas supply unit 130. The catalyst described in the above embodiment is arranged in the catalyst unit 161. The catalyst unit 161 converts the raw material gas into liquid fuel.

[0065] The separation section 162 has a separation membrane 112, a non-permeable side space 160A, and a permeable side space 160B.

[0066] Liquid fuel, water vapor, and residual fuel gas flow into the impermeable space 160A. The water vapor permeates through the separation membrane 112. Also, some of the hydrogen contained in the residual fuel gas permeates through the separation membrane 112. The liquid fuel flows out from the impermeable space 160A without permeating through the separation membrane 112.

[0067] Water vapor that has permeated through the separation membrane 112 flows into the permeate side space 160B. The sweep gas supplied from the sweep gas supply unit 120 flows into the permeate side space 160B. The exhaust gas containing the sweep gas, water vapor, and hydrogen flows out from the permeate side space 160B.

[0068] In this modified example, by having the sweep gas mainly consist of hydrogen or carbon dioxide, the hydrogen that permeates through the separation membrane 112 can be reused as part of the raw material gas without being separated from the sweep gas. As a result, the utilization rate of the raw material gas can be easily improved.

[0069] (Variation 3) In Figures 1 and 2, the source gas and sweep gas are shown flowing in opposite directions (i.e., opposite directions) in a side view of the separation membrane 112, but they may also flow in the same direction (i.e., parallel directions).

[0070] (Modification 4) In the above embodiment, the material gas supplied from the material gas source 131 is used as the refrigerant for the heat exchanger 132a, but this is not limited to this. Water or the like may be used as the refrigerant for the heat exchanger 132a. In this case, the material gas may be directly mixed with the sweep gas flowing out from the second drain trap 132b without passing through the heat exchanger 132a.

[0071] (Variation 5) In the above embodiment, the residual raw material gas separated from the liquid fuel in the first drain trap 140 is returned entirely to the raw material gas supply unit 130, but the embodiment is not limited to this.

[0072] For example, as shown in Figure 3, a portion of the residual raw material gas may be mixed with the sweep gas flowing out of the storage unit 121 and supplied to the flow rate adjustment mechanism 122. In this case, a portion of the residual raw material gas is used as part of the sweep gas. The amount of residual raw material gas mixed in can be adjusted by the flow rate adjustment mechanism 124.

[0073] Alternatively, as shown in Figure 4, all of the remaining raw material gas may be mixed with the sweep gas flowing out of the storage unit 121 and supplied to the flow rate adjustment mechanism 122. Since the flow of the remaining raw material gas is restricted from flowing towards the storage unit 121 by the check valve 125, it flows towards the flow rate adjustment mechanism 122. In this case, all of the remaining raw material gas is used as part of the sweep gas.

[0074] Furthermore, as shown in Figure 5, the sweep gas supply unit 120 may not have a storage unit 121, and a portion of the residual raw material gas may be supplied to the flow rate adjustment mechanism 122. In this case, a portion of the residual raw material gas is used as sweep gas. The amount of sweep gas (residual raw material gas) supplied can be adjusted by the flow rate adjustment mechanism 122.

[0075] Furthermore, as shown in Figure 6, the sweep gas supply unit 120 may not have a storage unit 121, and all of the remaining raw material gas may be supplied to the flow rate adjustment mechanism 122. In this case, all of the remaining raw material gas is used as sweep gas.

[0076] (Experimental variation 6) In the above embodiment, the separation membrane 112 is designed to allow water vapor, one of the products of the conversion reaction from raw gas to liquid fuel, to pass through, but it is not limited to this. The separation membrane 112 may also allow the liquid fuel itself, which is produced by the conversion reaction from raw gas to liquid fuel, to pass through. In this case as well, the reaction equilibrium of equation (1) above can be shifted to the product side.

[0077] Furthermore, when the separation membrane 112 allows liquid fuel to permeate, the reaction equilibrium can be shifted to the product side even when liquid fuel is produced by a reaction that does not generate water vapor (for example, 2H2 + CO₂ ⇔ CH₃OH). [Explanation of Symbols]

[0078] 1 Membrane reactor 100 Liquid Fuel Synthesis System 110 Liquid fuel synthesis department 111 Catalyst layer 112 Separation membrane 110A Non-transparent side space 110B Transmission side space 120 Sweeping Gas Supply Unit 130 Raw Material Gas Supply Department

Claims

1. A liquid fuel synthesis unit having a non-permeable space through which a conversion reaction from a raw material gas containing at least hydrogen and carbon dioxide to a liquid fuel proceeds, a separation membrane that allows the products of the conversion reaction to pass through, and a permeable space through which the products that have passed through the separation membrane flow in. A sweep gas supply unit supplies a sweep gas to the permeate side space for sweeping the product that has permeated through the separation membrane, Equipped with, The sweeping gas contains at least hydrogen and carbon dioxide, The sweeping gas contains hydrogen or carbon dioxide as its main component, The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis system.

2. A liquid fuel synthesis unit having a non-permeable space through which a conversion reaction from a raw material gas containing at least hydrogen and carbon dioxide to a liquid fuel proceeds, a separation membrane that allows the products of the conversion reaction to pass through, and a permeable space through which the products that have passed through the separation membrane flow in. A sweep gas supply unit supplies a sweep gas to the permeate side space for sweeping the product that has permeated through the separation membrane, Equipped with, The aforementioned sweeping gas contains hydrogen as its main component, The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis system.

3. The aforementioned sweeping gas contains carbon dioxide as a by-component. The liquid fuel synthesis system according to claim 2.

4. A liquid fuel synthesis unit having a non-permeable space through which a conversion reaction from a raw material gas containing at least hydrogen and carbon dioxide to a liquid fuel proceeds, a separation membrane that allows the products of the conversion reaction to pass through, and a permeable space through which the products that have passed through the separation membrane flow in. A sweep gas supply unit supplies a sweep gas to the permeate side space for sweeping the product that has permeated through the separation membrane, Equipped with, The aforementioned sweeping gas consists solely of carbon dioxide. The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis system.

5. The system includes a moisture removal unit that removes moisture from the exhaust gas discharged from the liquid fuel synthesis unit and containing the sweep gas and the products thereof. A liquid fuel synthesis system according to any one of claims 1 to 4.

6. The moisture removal unit includes a heat exchanger that uses a material gas containing at least hydrogen and carbon dioxide as a refrigerant. The liquid fuel synthesis system according to claim 5.

7. The system includes a pressure boosting unit that increases the pressure of the mixed gas of the material gas and the sweeping gas that has passed through the moisture removal unit and supplies it to the liquid fuel synthesis unit. The liquid fuel synthesis system according to claim 6.

8. The process includes supplying a raw material gas containing at least hydrogen and carbon dioxide to the permeable side space of the liquid fuel synthesis section to allow the conversion reaction from the raw material gas to liquid fuel to proceed, while simultaneously supplying a sweeping gas to the permeable side space of the liquid fuel synthesis section to sweep away the products generated by the conversion reaction that permeate the separation membrane, The sweeping gas contains at least hydrogen and carbon dioxide, The sweeping gas contains hydrogen or carbon dioxide as its main component, The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis method.

9. The process includes supplying a raw material gas containing at least hydrogen and carbon dioxide to the permeable side space of the liquid fuel synthesis section to allow the conversion reaction from the raw material gas to liquid fuel to proceed, while simultaneously supplying a sweeping gas to the permeable side space of the liquid fuel synthesis section to sweep away the products generated by the conversion reaction that permeate the separation membrane, The aforementioned sweeping gas contains hydrogen as its main component, The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis method.

10. The process includes supplying a raw material gas containing at least hydrogen and carbon dioxide to the permeable side space of the liquid fuel synthesis section to allow the conversion reaction from the raw material gas to liquid fuel to proceed, while simultaneously supplying a sweeping gas to the permeable side space of the liquid fuel synthesis section to sweep away the products generated by the conversion reaction that permeate the separation membrane, The aforementioned sweeping gas consists solely of carbon dioxide. The sweep gas discharged from the permeate side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as part of the raw material gas. A portion of the residual raw material gas discharged from the impermeable side space is used as at least a portion of the sweep gas. Liquid fuel synthesis method.

11. The process further comprises removing moisture from the exhaust gas containing the sweep gas and the product. A method for synthesizing liquid fuel according to any one of claims 8 to 10.

12. In the process of removing moisture from the exhaust gas, a source gas containing at least hydrogen and carbon dioxide is used as a refrigerant. The liquid fuel synthesis method according to claim 11.

13. The process further includes a step of increasing the pressure of the mixed gas of the material gas and the sweeping gas after it has been used as a refrigerant. The liquid fuel synthesis method according to claim 12.

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