JP7775084B2 - fuel synthesis device - Google Patents

Description

The present invention relates to a fuel synthesis device that synthesizes fuel from hydrogen and carbon dioxide.

In order to reduce the negative impact on the global environment, regulations on automobile exhaust gases are becoming more stringent.
As a technology for reducing adverse effects on the global environment, it has been proposed to synthesize fuel by mixing hydrogen ( _H2 ) and carbon dioxide ( _CO2 ) and passing the mixture through a reactor (reaction tube) equipped with a catalyst (see, for example, Patent Document 1). In Patent Document 1, _CO2 in exhaust gas emitted from an internal combustion engine is first adsorbed and then desorbed. The _{desorbed CO2} is mixed with separately supplied _H2 , pressurized by a compressor, and then introduced into a reactor equipped with a catalyst. The fluid that has passed through the reactor is subjected to gas-liquid separation to extract fuel.

An example of a catalyst (fuel synthesis catalyst) _that synthesizes fuel by reacting _H2 and _CO2 is a copper-zinc oxide catalyst. A copper-zinc oxide catalyst is a catalyst in which catalytic metal particles made of a transition metal such as copper ( _Cu ) or zinc (Zn) are supported on a carrier made of an oxide such as alumina (Al2O3) or silica ( _SiO2 ). This catalyst reduces _CO2 and can synthesize methanol ( _CH3OH ). This catalyst has a temperature range suitable for synthesizing fuel, which is 230 to 250°C. The reaction that synthesizes fuel (methanol) from _H2 and _CO2 is as shown in formula (1) below, and the heat of formation is 49 kJ/mol.
_CO2 + _3H2 → _CH3OH + _H2O ...(1)

This is a very exothermic reaction. As a result, the temperature at the downstream side of the catalyst rises, sometimes reaching 300°C or higher. When the temperature of the catalyst exceeds 300°C, a side reaction occurs as shown in formula (2) below, inhibiting the fuel synthesis reaction. Furthermore, copper is sensitive to heat, so the catalyst particles aggregate, reducing catalytic activity.
CO ₂ + H ₂ → CO + H ₂ O…(2)

For this reason, a technology has been proposed to cool the catalyst with water (industrial water) as a heat countermeasure for the catalyst (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2020-164424 Japanese Patent Application Laid-Open No. 2005-132739

However, the technology described in Patent Document 2 requires separate equipment (device) for water cooling and an external supply of industrial water.

The present invention was made in consideration of the above situation, and its objective is to provide a fuel synthesis device that can control the temperature of a fuel synthesis catalyst without using a separate device or industrial water.

In order to solve the above problem, the invention of claim 1 is a fuel synthesis device comprising: a supply means arranged upstream of a main passage for supplying _CO2 gas and _H2 gas; a fuel synthesis catalyst arranged downstream of the supply means for chemically reacting the _CO2 gas and the _H2 gas to synthesize fuel; a gas-liquid separation means arranged downstream of the fuel synthesis catalyst for liquefying the fuel and separating it from the _CO2 gas and _H2 gas that were not reacted in the fuel synthesis catalyst; and a cooling means for returning the liquid separated by the gas-liquid separation means to the periphery of the fuel synthesis catalyst and then cooling the fuel synthesis catalyst by flowing the liquid downstream of the gas-liquid separation means.

In this way, the invention of claim 1 recirculates fuel synthesized using a fuel synthesis catalyst and liquefied using a gas-liquid separation means around the fuel synthesis catalyst, thereby making it possible to control the temperature of the fuel synthesis catalyst without using a separate cooling device (facility) or industrial water.

The invention of claim 2 is the fuel synthesis device of claim 1, wherein the fuel synthesis catalyst is equipped with a catalyst temperature measurement means for measuring the temperature of the fuel synthesis catalyst, and the cooling means is equipped with a first control valve provided downstream of the gas-liquid separation means and a cooling passage connected to the first control valve, which circulates around the fuel synthesis catalyst and is connected downstream of the first control valve, and the first control valve is controlled to open and close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measurement means. The opening and closing control is performed by opening the valve when the temperature rises and closing the valve when the temperature drops, and the valve opening is adjusted as needed.

In this way, the invention according to claim 2 controls the opening and closing of the first control valve in accordance with the temperature of the fuel synthesis catalyst, and allows the liquid separated by the gas-liquid separation means to be circulated appropriately, thereby controlling the temperature of the fuel synthesis catalyst within an appropriate range.

The invention of claim 3 is the fuel synthesis device of claim 2, wherein the cooling passage includes a bypass passage that bypasses the fuel synthesis catalyst upstream, and a second control valve is provided in the bypass passage, and the second control valve is controlled to open and close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measurement means, allowing the liquid to flow directly into the fuel synthesis catalyst.

In this way, according to the invention of claim 3, when further cooling of the fuel synthesis catalyst is required, the second control valve opens and closes in response to the temperature of the fuel synthesis catalyst measured by the catalyst temperature measurement means, allowing the separated liquid to flow directly into the fuel synthesis catalyst to cool it. Therefore, the invention of claim 3 can more quickly and reliably control the temperature of the fuel synthesis catalyst.

The invention of claim 4 is the fuel synthesis device described in claim 3, characterized in that a third control valve is provided in the main passage upstream of the fuel synthesis catalyst, and the third control valve is controlled to open and close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measurement means.

In this way, when further cooling of the fuel synthesis catalyst is required, the invention according to claim 4 can reduce the reaction in the fuel synthesis catalyst by controlling the _CO2 gas and _H2 gas supplied to the fuel synthesis catalyst from the main passage. Therefore, the invention according to claim 4 can more reliably control the temperature of the fuel synthesis catalyst.

The invention of claim 5 is the fuel synthesis device of claim 4, characterized in that when the temperature of the fuel synthesis catalyst reaches or exceeds a predetermined temperature, first catalyst temperature control is performed by controlling the first control valve to open and close, the second control valve to close, and the third control valve to open; and if, after performing the first catalyst temperature control, the temperature of the fuel synthesis catalyst does not fall below the predetermined temperature, second catalyst temperature control is performed by controlling the second control valve to open and close, and the third control valve to close.

In this way, the invention of claim 5 performs first catalyst temperature control and second catalyst temperature control, thereby performing step-by-step cooling control according to the temperature of the fuel synthesis catalyst. As a result, the invention of claim 5 can maximize fuel synthesis while controlling the temperature of the fuel synthesis catalyst, and can perform control to reduce catalytic reaction when the fuel synthesis catalyst is at a high temperature. Therefore, the invention of claim 5 can suppress the adverse effects of heat on the fuel synthesis catalyst.

The invention of claim 6 is the fuel synthesis device of claim 5, characterized in that the case in which the temperature of the fuel synthesis catalyst does not fall below the predetermined temperature is when the temperature of the fuel synthesis catalyst is equal to or higher than the predetermined temperature after a predetermined time has elapsed since the first catalyst temperature control was performed, or when the temperature of the fuel synthesis catalyst is equal to or higher than a second predetermined temperature that is higher than the predetermined temperature.

In this way, the invention of claim 6 can reliably perform stepwise cooling control based on changes in the temperature of the fuel synthesis catalyst, in accordance with the criteria for when the temperature of the fuel synthesis catalyst does not fall below the predetermined temperature. Therefore, the invention of claim 6 can more appropriately perform control to maximize fuel synthesis while controlling the temperature of the fuel synthesis catalyst, and reduce catalytic reactions when the fuel synthesis catalyst is at a high temperature. Therefore, the invention of claim 6 can suppress the adverse effects of heat on the fuel synthesis catalyst.

The present invention provides a fuel synthesis device that can control the temperature of a fuel synthesis catalyst without using a separate device or industrial water.

1 is a schematic diagram showing the configuration of a fuel synthesis device according to an embodiment of the present invention. 1 is a graph showing an example of the temperature of the fuel synthesis catalyst when the first control valve, the second control valve, and the third control valve are controlled to open and close, in which the horizontal axis represents time and the vertical axis represents the temperature of the fuel synthesis catalyst. 3 is a flowchart for controlling the temperature of a fuel synthesis catalyst in the fuel synthesis device according to the present embodiment.

A fuel synthesis device 1 according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, the terms "upstream,""upstreamside,""downstream," and "downstream side" refer to the upstream side and downstream side in the flow direction of a fluid flowing through the device being described.
Of the drawings to be referred to, Fig. 1 is a schematic diagram showing the configuration of a fuel synthesis device 1 according to this embodiment. Fig. 2 is a graph showing an example of the temperature of the fuel synthesis catalyst 3 when the first control valve V1, the second control valve V2, and the third control valve V3 are controlled to open and close.

First, the configuration of each passage in the fuel synthesis device 1 will be described. The fuel synthesis device 1 has a main passage 10, which synthesizes fuel from supplied gas and separates the fuel, and a return passage 20, which returns the gas remaining in the gas phase after fuel separation to the main passage 10 upstream of the fuel synthesis catalyst 3. The main passage 10 has pipes 11, 12, 13, 14, and 15. The fuel synthesis device 1 also has an ECU (Electronic Control Unit) 60 outside these passages. The ECU 60 controls various adjustment valves, such as the first control valve V1, second control valve V2, and third control valve V3 (described below), and other switching devices based on the values of various sensors located in each passage. The ECU 60 also controls the compressor 30, heater 40, distillation heating means 6, and other devices based on the values of various sensors.

As shown in FIG. 1, the fuel synthesis device 1 includes a supply means 2, a fuel synthesis catalyst 3, a gas-liquid separation means 4, and a cooling means 5 on the main passage 10. The fuel synthesis device 1 includes the fuel synthesis catalyst 3 downstream of the supply means 2, the gas-liquid separation means 4 downstream of the fuel synthesis catalyst 3, and the cooling means 5 downstream of the gas-liquid separation means 4. The cooling means 5 is formed by a pipe branching from the first control valve V1 and spiraling around the fuel synthesis catalyst 3 while abutting the catalyst (more specifically, while abutting the reactor tube 31 described below, which houses the catalyst 3). The downstream end of this pipe is connected downstream of the first control valve V1. A distillation heating means 6 is provided downstream of the downstream end of this pipe. The first control valve V1 may be a switching valve.

The fuel synthesis device 1 also includes a compressor 30 for compressing gas and a heater 40 for heating the compressed gas, located between the supply means 2 and the fuel synthesis catalyst 3. The compressor 30 and heater 40 are connected via piping 12 in the main passage 10. The compressor 30 compresses the gas to a pressure of 10 MPa. The heater 40 heats the gas to a temperature of 230 to 250°C. The gas pressure and temperature can be set appropriately depending on the characteristics of the fuel synthesis catalyst 3, etc.

The supply means 2 is connected to the compressor 30 via the pipe 11 of the main passage 10. The supply means 2 supplies _CO2 gas and _H2 gas to the main passage 10.
The _CO2 gas is supplied from a tank 21 that stores _CO2 gas. The amount of _CO2 gas supplied is controlled by the ECU 60. The _CO2 gas may be _CO2 in the exhaust gas emitted from an internal combustion engine of a vehicle such as an automobile or in the atmosphere, which has been adsorbed by an adsorbent. In this case, the _CO2 can be desorbed as needed and used as a _CO2 tank.

The _H2 gas is supplied from a tank 22 that stores the _H2 gas. The amount of _H2 gas supplied is controlled by the ECU 60. The _H2 gas can also be obtained by electrolyzing water produced by a fuel cell or the like.

The fuel synthesis catalyst 3 is disposed downstream of the supply means 2 and synthesizes fuel by chemically reacting _CO2 gas and _H2 gas. The fuel to be synthesized is, for example, methanol. The fuel synthesis catalyst 3 is a carbon dioxide reduction catalyst and is disposed in a reaction tube 31 disposed in the main passage 10. The upstream side of the reaction tube 31 is connected to a pipe 13 of the main passage 10 and the downstream side is connected to a pipe 14 of the main passage 10. The gas supplied from the upstream side of the fuel synthesis catalyst 3 in the main passage 10 contains _CO2 and _H2 . _{The CO2} and _H2 undergo a chemical reaction (hydrogenation reaction) in a predetermined ratio in the reaction tube 31. The fuel synthesis catalyst 3 reduces _CO2 in the presence of _CO2 and _H2 and promotes the hydrogenation reaction of _CO2 to produce methanol ( _CH3OH ) as a fuel. As the carbon dioxide reduction catalyst, for example, a known catalyst such as a _copper - _zinc oxide catalyst in which a catalytic metal made of a transition metal such as copper (Cu) or zinc ( _Zn ) is supported on a carrier made of an oxide such as alumina (Al 2 O 3 ) or silica (SiO 2 ) is used.

The fuel synthesis process using the fuel synthesis catalyst 3 can be performed using well-known techniques. For example, H ₂ measured so that the ratio of CO ₂ to H ₂ in the reaction tube 31 is a predetermined ratio is supplied from the tank 22 to the pipe 11, and the gas in the reaction tube 31 is heated and compressed by the compressor 30 and heater 40. As a result, under the action of the carbon dioxide reduction catalyst, a CO ₂ hydrogenation reaction (see formula (3) below) proceeds in the reaction tube 31, producing methanol (CH ₃ OH) as fuel. At the same time, the action of the carbon dioxide reduction catalyst also proceeds with a reverse water gas shift reaction (see formula (4) below) and a carbon monoxide (CO) hydrogenation reaction (see formula (5) below), producing a synthesis gas containing methanol. The pressure in the reaction tube 31 increased by the compressor 30 can be reduced by a back pressure valve (not shown) provided in the reaction tube 31.
_CO2 + _3H2 → _CH3OH + _H2O ...(3)
CO ₂ + H ₂ → CO + H ₂ O…(4)
CO+ _2H2 → _CH3OH ...(5)

The gas-liquid separation means 4 is disposed downstream of the fuel synthesis catalyst 3, specifically between pipes 14 and 15 in the main passage 10, and liquefies the fuel and separates it from the _CO2 gas and _H2 gas that were unreacted in the fuel synthesis catalyst 3. The gas-liquid separation means 4 separates the unreacted gas (gas phase) from a liquid (liquid phase) mainly composed of methanol by cooling and condensing the methanol-containing synthesis gas through heat exchange. The gas-liquid separation means 4 can also separate the liquid (liquid phase) mainly composed of methanol by membrane separation of the synthesis gas. The liquid phase mainly composed of methanol separated by the gas-liquid separation means 4 flows through pipe 15 and is supplied to the distillation heating means 6. The gas phase separated by the gas-liquid separation means 4 contains by-product CO, unreacted CO2 and _{H2 ,} as well as unrecovered methanol and water ( _H2O ). The gas separated as a gas phase by the gas-liquid separation means 4 flows through the reflux passage 20 and is supplied upstream of the fuel synthesis catalyst 3, where it is used again for fuel synthesis.

The distillation heating means 6 separates the methanol and water contained in the liquid phase by utilizing the difference in boiling points. The distillation heating means 6 heats the liquid phase to approximately 65°C. As a result, methanol ( _CH3OH ) is evaporated from the liquid phase and is obtained. This is supplied to a fuel tank (not shown) via pipe 16 either as a gas or liquefied. The remaining liquid phase is mostly water ( _H2O ), and is discharged to the outside via pipe 17.

The cooling means 5 is positioned downstream of the gas-liquid separation means 4 and returns the liquid separated by the gas-liquid separation means 4 to the area around the fuel synthesis catalyst 3 (more specifically, around the reaction tube 31 containing the fuel synthesis catalyst 3), after which the liquid is allowed to flow downstream of the gas-liquid separation means 4 to cool the fuel synthesis catalyst 3. The liquid separated by the gas-liquid separation means 4 is preferably subjected to heat exchange or cooling as necessary, and kept at a temperature of approximately 15°C, although this is not limited to this. Maintaining the liquid at this temperature ensures a reliable cooling effect.

In this way, the fuel synthesis device 1 circulates the liquid separated by the gas-liquid separation means 4 around the fuel synthesis catalyst 3, so that the temperature of the fuel synthesis catalyst 3 can be controlled without using a separate cooling device (facility) or industrial water.
The fuel synthesizing device 1 synthesizes fuel (methanol) using carbon dioxide, thereby reducing carbon dioxide emissions and mitigating adverse effects on the global environment.

A preferred embodiment of the fuel synthesizing device 1 will now be described.
The fuel synthesis catalyst 3 may be equipped with a catalyst temperature measuring means 32 (temperature sensor) that measures the temperature of the fuel synthesis catalyst 3. The cooling means 5 may also include a first control valve V1 provided downstream of the gas-liquid separating means 4, and a cooling passage 51 connected to the first control valve V1, which circulates around the fuel synthesis catalyst 3 and is connected downstream of the first control valve V1. In this embodiment, the first control valve V1 can be controlled to open and close in accordance with the temperature of the fuel synthesis catalyst 3 measured by the catalyst temperature measuring means 32. By controlling the opening and closing of the first control valve V1, the ratio of liquid flowing to the cooling means 5 and liquid flowing to the distillation heating means 6 can be adjusted in accordance with the temperature of the fuel synthesis catalyst 3. The opening and closing of the first control valve V1 can also be controlled to allow liquid to flow to only one of the cooling means 5 and the distillation heating means 6.

In this configuration, the fuel synthesis device 1 controls the opening and closing of the first control valve V1 in accordance with the temperature of the fuel synthesis catalyst 3 measured by the catalyst temperature measurement means 32, and can appropriately circulate the liquid separated by the gas-liquid separation means 4 around the fuel synthesis catalyst 3 through the cooling passage 51. Therefore, the fuel synthesis device 1 can control the temperature of the fuel synthesis catalyst 3 within an appropriate range.

The cooling passage 51 includes a bypass passage 52 that bypasses the fuel synthesis catalyst 3 upstream, and this bypass passage 52 may be provided with a second control valve V2. The second control valve V2 may be a switching valve. The second control valve V2 is controlled to open and close in accordance with the temperature of the fuel synthesis catalyst 3 measured by the catalyst temperature measurement means 32, allowing liquid to flow directly into the fuel synthesis catalyst 3. The opening and closing control of the second control valve V2 not only allows the valve to be opened and closed, but also allows the valve opening to be adjusted in accordance with the temperature of the fuel synthesis catalyst 3, thereby adjusting the amount of liquid flowing into the fuel synthesis catalyst 3.

In this configuration, when the temperature of the fuel synthesis catalyst 3 does not decrease and further cooling is required, the fuel synthesis device 1 can control the opening and closing of the second control valve V2 in accordance with the temperature of the fuel synthesis catalyst 3 measured by the catalyst temperature measurement means 32. The liquid separated through the bypass passage 52 then flows directly into the fuel synthesis catalyst 3, cooling it. Furthermore, since the main component of this liquid is the product methanol (which also contains water), the reaction in the fuel synthesis catalyst 3 can be stopped in chemical equilibrium by increasing the concentrations of methanol and water. Therefore, the fuel synthesis device 1 can more quickly and reliably control the temperature of the fuel synthesis catalyst 3.

A third control valve V3 may be provided in the main passage 10 upstream of the fuel synthesis catalyst 3. The third control valve V3 can be controlled to open or close in response to the temperature of the fuel synthesis catalyst 3 measured by the catalyst temperature measuring means 32.

In this configuration, when the temperature of the fuel synthesis catalyst 3 does not decrease and further cooling of the fuel synthesis catalyst 3 is required, the fuel synthesis device 1 can control the CO2 gas _{and H2} gas supplied from the main passage 10 to the fuel synthesis catalyst 3 by controlling the opening and closing of the third control valve _V3 (for example, adjusting the valve opening). Therefore, the fuel synthesis device 1 can control the reaction in the fuel synthesis catalyst 3 to decrease, and can more reliably control the temperature of the fuel synthesis catalyst 3.

In addition, as a preferred embodiment, the following first catalyst temperature control and second catalyst temperature control are performed.
The first catalyst temperature control is performed by controlling the opening and closing of the first control valve V1, controlling the closing of the second control valve V2, and controlling the opening of the third control valve V3 when the temperature of the fuel synthesis catalyst 3 reaches or exceeds a predetermined temperature.
In the second catalyst temperature control, if the temperature of the fuel synthesis catalyst 3 does not fall below a predetermined temperature after the first catalyst temperature control described above is performed, the second control valve V2 is controlled to open and close, and the third control valve V3 is controlled to close.
The predetermined temperature in the first catalyst temperature control and the second catalyst temperature control may be, for example, but is not limited to, 300° C. This predetermined temperature can be set arbitrarily taking into consideration the properties and performance of the fuel synthesis catalyst 3 used, the fuel synthesis rate, the by-product generation rate, etc.

When first catalyst temperature control is performed, the first control valve V1 is controlled to open/close, the second control valve V2 is controlled to close, and the third control valve V3 is controlled to open, so that the temperature of the fuel synthesis catalyst 3 can be lowered, for example, as shown by the dashed line in Figure 2. If the temperature of the fuel synthesis catalyst 3 can be maintained at a low level, the first control valve V1 is controlled to close, stopping the supply of liquid to the cooling means 5, and all of the liquid separated by the gas-liquid separation means 4 is supplied to the distillation heating means 6.

However, even when the first catalyst temperature control is performed, there may be cases where the temperature of the fuel synthesis catalyst 3 does not decrease, as shown by the dashed line in Figure 2. In such cases, the second catalyst temperature control described above is performed, controlling the second control valve V2 to open or close and the third control valve V3 to close, thereby lowering the temperature of the fuel synthesis catalyst 3. Thereafter, once the temperature of the fuel synthesis catalyst 3 decreases, the first control valve V1 and the second control valve V2 are closed and the third control valve V3 is opened to resume fuel synthesis. If the temperature of the fuel synthesis catalyst 3 does not decrease, an abnormality (e.g., poor temperature control or thermal runaway) may have occurred. Therefore, a warning is issued to the user to indicate this, and the fuel synthesis device 1 is stopped. The warning can be issued by voice, beep, or displayed on a screen.

In this configuration, the fuel synthesis device 1 performs first catalyst temperature control and second catalyst temperature control, allowing for stepwise cooling control according to the temperature of the fuel synthesis catalyst 3. This allows the fuel synthesis device 1 to maximize fuel synthesis while controlling the temperature of the fuel synthesis catalyst 3, and to perform control that reduces catalytic reactions when the fuel synthesis catalyst 3 is at a high temperature. Therefore, the fuel synthesis device 1 can suppress the adverse effects of heat on the fuel synthesis catalyst 3.

Here, the case where the temperature of the fuel synthesis catalyst 3 does not fall below the predetermined temperature refers to when the temperature of the fuel synthesis catalyst 3 is equal to or higher than the predetermined temperature after a predetermined time has elapsed since the first catalyst temperature control was performed, or when the temperature of the fuel synthesis catalyst 3 is equal to or higher than a second predetermined temperature that is higher than the predetermined temperature. Here, the predetermined time can be, for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes, but is not limited to these and can be set as desired. The second predetermined temperature can be, for example, 310°C, 320°C, or 330°C, but is not limited to these and can be set as desired depending on the properties and performance of the fuel synthesis catalyst 3.

In this configuration, the fuel synthesis device 1 can reliably perform stepwise cooling control based on changes in the temperature of the fuel synthesis catalyst 3, in accordance with the criteria for when the temperature of the fuel synthesis catalyst 3 does not fall below a predetermined temperature. Therefore, the fuel synthesis device 1 can maximize fuel synthesis while controlling the temperature of the fuel synthesis catalyst 3, and more appropriately perform control to reduce catalytic reactions when the fuel synthesis catalyst 3 is at a high temperature. Therefore, the fuel synthesis device 1 can suppress the adverse effects of heat on the fuel synthesis catalyst 3.

Next, a preferred mode of temperature control of the fuel synthesis catalyst 3 in the fuel synthesis device 1 according to this embodiment will be described with reference to Figure 3. Figure 3 is a flowchart for controlling the temperature of the fuel synthesis catalyst 3 in the fuel synthesis device 1 according to this embodiment.

As shown in Figure 3, the fuel synthesizer 1 starts operating. During normal operation of the fuel synthesizer 1, the first control valve V1 is closed, and the liquid separated by the gas-liquid separation means 4 flows through the main passage 10 and is supplied to the distillation heating means 6, and does not flow into the reflux passage 20. The second control valve V2 is closed, and the liquid separated by the gas-liquid separation means 4 does not flow from the bypass passage 52 into the main passage 10. The third control valve V3 is open, and _CO2 gas and _H2 gas can flow through.

When the fuel synthesis device 1 begins operation, the catalyst temperature measurement means 32 measures the temperature of the fuel synthesis catalyst 3 (step S1). If the temperature of the fuel synthesis catalyst 3 is below a predetermined temperature (e.g., 300°C) in step S1, the ECU 60 controls the first control valve V1 to remain closed (step S2). The ECU 60 also controls the second control valve V2 and the third control valve V3 to remain immobile, i.e., to keep the second control valve V2 closed and the third control valve V3 open (step S3). In this case, there is no problem with the temperature of the fuel synthesis catalyst 3, so the process returns to step S1 and the operation of the fuel synthesis device 1 and the measurement of the temperature of the fuel synthesis catalyst 3 by the catalyst temperature measurement means 32 continue.

On the other hand, if the temperature of the fuel synthesis catalyst 3 exceeds a predetermined temperature (e.g., 300°C) in step S1, the ECU 60 controls the opening and closing of the first control valve V1 in accordance with the temperature of the fuel synthesis catalyst 3 (step S4). As a result, the fuel synthesis device 1 circulates liquid around the fuel synthesis catalyst 3, cooling it. The ECU 60 also controls the second control valve V2 and the third control valve V3 to remain immobile, i.e., to keep the second control valve V2 closed and the third control valve V3 open (step S5). Next, the catalyst temperature measurement means 32 measures the temperature of the fuel synthesis catalyst 3 (step S6).

If the temperature of the fuel synthesis catalyst 3 is below a predetermined temperature (e.g., 300°C) in step S6, the ECU 60 closes the first control valve V1 (step S7) and stops cooling the fuel synthesis catalyst 3 by refluxing the liquid. The ECU 60 also controls the second control valve V2 and the third control valve V3 to remain immobile, i.e., the second control valve V2 remains closed and the third control valve V3 remains open (step S8). In this case, there is no problem with the temperature of the fuel synthesis catalyst 3, so the process returns to step S1 and the operation of the fuel synthesis device 1 and measurement of the temperature of the fuel synthesis catalyst 3 by the catalyst temperature measurement means 32 continue.

On the other hand, if the temperature of the fuel synthesis catalyst 3 exceeds a predetermined temperature (e.g., 300°C) in step S6 (if it does not fall below the predetermined temperature), the ECU 60 controls the opening and closing of the first control valve V1 and also controls the opening and closing of the second control valve V2 depending on the temperature of the fuel synthesis catalyst 3 (step S9). The ECU 60 also controls the closing of the third control valve V3 (step S10) to stop the supply of _CO2 gas and _H2 gas to the fuel synthesis catalyst 3. Next, the operation of the fuel synthesis device 1 is stopped (step S11). When the operation of the fuel synthesis device 1 is stopped, a warning may be issued to the user, as described above.

As described above, the fuel synthesis device 1 according to this embodiment is equipped with a cooling device 5 that returns the liquid separated by the gas-liquid separation device 4 to the periphery of the fuel synthesis catalyst 3, and then cools the fuel synthesis catalyst 3 by flowing the liquid downstream of the gas-liquid separation device 4. Therefore, the fuel synthesis device 1 can control the temperature of the fuel synthesis catalyst 3 without using a separate cooling device (facility) or industrial water.

The present invention is not limited to the embodiments described above and can be implemented in various forms. Furthermore, the above embodiments can be combined to the extent structurally possible.

REFERENCE SIGNS LIST 1 fuel synthesis device 2 supply means 3 fuel synthesis catalyst 4 gas-liquid separation means 5 cooling means 6 distillation heating means 10 main passage 11 to 17 piping 20 reflux passage 21, 22 tank 30 compressor 31 reaction tube 32 catalyst temperature measuring means 40 heater 51 cooling passage 52 bypass passage 60 ECU
V1 First control valve V2 Second control valve V3 Third control valve

Claims (6)

a supply means disposed upstream of the main passage for supplying carbon dioxide gas and hydrogen gas;
a fuel synthesis catalyst disposed downstream of the supply means for chemically reacting the carbon dioxide gas and the hydrogen gas to synthesize a fuel;
a gas-liquid separation means disposed downstream of the fuel synthesis catalyst for converting the fuel into a liquid and separating the liquid from the carbon dioxide gas and the hydrogen gas that have not reacted in the fuel synthesis catalyst;
a cooling means for returning the liquid separated by the gas-liquid separation means to the periphery of the fuel synthesis catalyst, and then causing the liquid to flow downstream of the gas-liquid separation means to cool the fuel synthesis catalyst;
A fuel synthesis device comprising: the fuel synthesis catalyst is provided with a catalyst temperature measuring means for measuring the temperature of the fuel synthesis catalyst;
the cooling means includes a first control valve provided downstream of the gas-liquid separation means, and a cooling passage connected to the first control valve, for circulating around the fuel synthesis catalyst, and connected downstream of the first control valve;
2. The fuel synthesis device according to claim 1, wherein the first control valve is controlled to open or close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measuring means. the cooling passage includes a bypass passage that bypasses the fuel synthesis catalyst upstream,
a second control valve is provided in the bypass passage;
3. The fuel synthesis device according to claim 2, wherein the second control valve is controlled to open or close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measuring means, and causes the liquid to flow directly into the fuel synthesis catalyst. a third control valve is provided in the main passage upstream of the fuel synthesis catalyst;
4. The fuel synthesis device according to claim 3, wherein the third control valve is controlled to open or close in accordance with the temperature of the fuel synthesis catalyst measured by the catalyst temperature measuring means. When the temperature of the fuel synthesis catalyst reaches or exceeds a predetermined temperature, first catalyst temperature control is performed in which the first control valve is controlled to open and close, the second control valve is controlled to close, and the third control valve is controlled to open;
5. The fuel synthesis device according to claim 4, wherein, if the temperature of the fuel synthesis catalyst does not become lower than the predetermined temperature after the first catalyst temperature control is performed, a second catalyst temperature control is performed in which the second control valve is controlled to open and close and the third control valve is controlled to close. 6. The fuel synthesis device according to claim 5, wherein the case where the temperature of the fuel synthesis catalyst does not become lower than the predetermined temperature is when the temperature of the fuel synthesis catalyst is equal to or higher than the predetermined temperature after a predetermined time has elapsed since the first catalyst temperature control was performed, or when the temperature of the fuel synthesis catalyst is equal to or higher than a second predetermined temperature that is higher than the predetermined temperature.