JP2021148044A - Carbon dioxide separation and recovery device - Google Patents

Abstract

To provide a carbon dioxide separation and recovery device mountable to a vehicle and capable of sufficiently separating and recovering carbon dioxide included in exhaust gas of an internal combustion engine.SOLUTION: A CO2 recovery device 3 sequentially repeats four processes comprising: a first process of controlling a first valve 320, a second valve 340, a third valve 370 and a fourth valve 390 to adsorb carbon dioxide in exhaust gas to a lithium composite oxide layer 34; a second process of emitting carbon dioxide-removed exhaust gas; a third process of increasing a temperature of the lithium composite oxide layer 34 to desorb and recover the carbon dioxide from the lithium composite oxide layer 34; and a four process of lowering the temperature of the lithium composite oxide layer 34.SELECTED DRAWING: Figure 5

Description

The present invention relates to a carbon dioxide separation and recovery device.

Conventionally, a carbon dioxide adsorbent has been used to separate and recover carbon dioxide contained in exhaust gas. For example, the carbon dioxide adsorbent described in Patent Document 1 utilizes the carbon dioxide adsorption / desorption property of a lithium composite oxide.

Japanese Patent No. 3634747

However, conventional carbon dioxide adsorbents have not been sufficiently studied especially when mounted on a vehicle, and carbon dioxide contained in the exhaust gas discharged from the internal combustion engine cannot be sufficiently separated and recovered. It was the current situation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a carbon dioxide separation and recovery device that can be mounted on a vehicle and can sufficiently separate and recover carbon dioxide contained in the exhaust gas of an internal combustion engine.

(1) A carbon dioxide separation / recovery device that separates and recovers carbon dioxide contained in the exhaust of an internal combustion engine (for example, engine 1 described later), and is a lithium composite oxide layer made of a lithium composite oxide (for example, A carbon dioxide separation structure having a lithium composite oxide layer 34) described later (for example, a carbon dioxide separation structure 30 described later) and a first flow path (for example, a first flow path described later) for guiding exhaust to the carbon dioxide separation structure. 1 flow path 310), a first valve that opens and closes the first flow path (for example, the first valve 320 described later), and a second that guides carbon dioxide and decarbon dioxide exhaust separated by the carbon dioxide separation structure. A flow path (for example, a second flow path 350 described later), a second valve for adjusting the flow rate of the second flow path (for example, a second valve 340 described later), and decarbonization exhaust from the second flow path. A third flow path to be guided (for example, a third flow path 360 described later), a third valve for opening and closing the third flow path (for example, a third valve 370 described later), and carbon dioxide are guided from the second flow path. A carbon dioxide separation mechanism (for example, described later) having a fourth flow path (for example, a fourth flow path 380 described later) and a fourth valve (for example, a fourth valve 390 described later) for opening and closing the fourth flow path. The carbon dioxide separation mechanism 300) and the first valve are opened to throttle the second valve, and the third valve is opened to close the fourth valve, whereby carbon dioxide contained in the exhaust is combined with the lithium. The first step of adsorbing to the oxide layer, the first valve is closed to open the second valve, and the third valve is opened to close the fourth valve to release carbon dioxide exhaust to the third valve. The second step of guiding and releasing the carbon dioxide through the flow path, closing the first valve to open the second valve, closing the third valve to open the fourth valve, and raising the lithium composite oxide layer. The third step of desorbing carbon dioxide from the lithium composite oxide layer by warming it and guiding it through the fourth flow path for recovery, the first valve is closed, the second valve is opened, and the valve is opened. A control unit that controls the carbon dioxide separation mechanism so as to repeatedly execute the fourth step of closing the third valve, opening the fourth valve, and lowering the temperature of the lithium composite oxide layer in this order (for example, described later). A carbon dioxide separation / recovery device (for example, a carbon dioxide separation / recovery device 3 described later) including the control unit 9) of the above is provided.

In the carbon dioxide separation / recovery device (1), the carbon dioxide in the exhaust is lithium by controlling the first valve 320, the second valve 340, the third valve 370, and the fourth valve 390 that constitute the carbon dioxide separation mechanism. The first step of adsorbing to the composite oxide layer, the second step of releasing carbon dioxide exhaust, and the second step of raising the temperature of the lithium composite oxide layer to desorb and recover carbon dioxide from the lithium composite oxide layer. The configuration is such that the four steps of the three steps and the fourth step of lowering the temperature of the lithium composite oxide layer are repeatedly executed in this order. This makes it possible to efficiently perform selective chemisorption, separation, and recovery of carbon dioxide by the lithium composite oxide layer having carbon dioxide adsorption / desorption characteristics. Further, since the lithium composite oxide layer is used, the device can be miniaturized. Therefore, according to the invention of (1), it is possible to provide a carbon dioxide separation / recovery device that can be mounted on a vehicle and can sufficiently separate and recover carbon dioxide contained in the exhaust gas of an internal combustion engine.

(2) In the carbon dioxide separation and recovery device of (1), at least four carbon dioxide separation mechanisms are provided and arranged in parallel, and the control unit is provided among the four carbon dioxide separation mechanisms among at least four carbon dioxide separation mechanisms. By shifting the execution timing of the steps, each of the carbon dioxide separation mechanisms may be controlled so that any of the carbon dioxide separation mechanisms always executes the first step.

In the carbon dioxide separation / recovery device (2), by shifting the execution timing of the four steps among at least four carbon dioxide separation mechanisms, it is controlled so that one of the carbon dioxide separation mechanisms always executes the first step. do. As a result, the exhaust gas discharged from the internal combustion engine can always be introduced into one of the carbon dioxide separation mechanisms, and carbon dioxide can be continuously separated and recovered. Therefore, according to the invention of (2), it can be preferably used for vehicle mounting where continuous separation and recovery of carbon dioxide are required.

(3) In the carbon dioxide separation / recovery device of (1) or (2), the carbon dioxide separation / recovery device is provided on the upstream side of the first flow path and applies a positive pressure to the first flow path. A compressor (for example, a compressor 17 described later) may be provided.

The carbon dioxide separation and recovery device (3) is configured to include a compressor. As a result, a positive pressure can be applied to the first flow path by the compressor, so that the supply pressure to the carbon dioxide separation mechanism can be applied to the exhaust gas discharged from the internal combustion engine, which is more efficient. Carbon dioxide can be separated and recovered well.

(4) In any of the carbon dioxide separation and recovery devices (1) to (3), the carbon dioxide separation mechanism is an expander that applies negative pressure to the second flow path (for example, an expander 18 described later). May have.

In the carbon dioxide separation / recovery device of (4), the carbon dioxide separation mechanism has an expander. As a result, a negative pressure can be applied to the second flow path by suction by the expander, so that carbon dioxide adsorbed on the lithium composite oxide layer can be positively desorbed.

(5) In any of the carbon dioxide separation and recovery devices (1) to (4), the carbon dioxide separation structure is a silicon thin film substrate that generates heat by energization due to doping with impurities (for example, a silicon thin film substrate described later). A thin film layer (for example, a thin film layer 35 described later) having the lithium composite oxide layer (for example, the lithium composite oxide layer 34 described later) provided on the silicon thin film substrate may be provided.

In the carbon dioxide separation / recovery device (5), the carbon dioxide separation structure is configured to include a thin film layer having a silicon thin film substrate that generates heat by energization due to doping with impurities and a lithium composite oxide layer. .. As a result, the lithium composite oxide having carbon dioxide adsorption / desorption characteristics is formed as a thin film having an extremely small heat capacity, so that it can be miniaturized and has an extremely fast response in the temperature-dependent adsorption / desorption reaction of carbon dioxide. Properties can be obtained, and carbon dioxide can be efficiently adsorbed and desorbed. In addition, since it is provided with a silicon thin film substrate that is doped with impurities and instantaneously heats up by energization, it is possible to rapidly heat the carbon dioxide separation structure, and because it is a thin film, it is also possible to quench naturally, so it is temperature dependent. It is possible to more efficiently adsorb and desorb carbon dioxide having. Therefore, according to the carbon dioxide separation / recovery device of (5), carbon dioxide that can be mounted on a vehicle and contained in the exhaust gas of an internal combustion engine can be sufficiently separated and recovered.

According to the present invention, it is possible to provide a carbon dioxide separation / recovery device that can be mounted on a vehicle and can sufficiently separate and recover carbon dioxide contained in the exhaust gas of an internal combustion engine.

It is a figure which shows the structure of the vehicle which carries the carbon recycling system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the CO _{2 recovery apparatus.} It is a perspective view which shows the structure of the carbon dioxide separation structure. It is an enlarged view of the thin film layer which constitutes a carbon dioxide separation structure. It is a figure for demonstrating the operation of a CO ₂ recovery apparatus, (A) shows the state of the 1st process, (B) shows the state of a 2nd process, (C) shows the state of a 3rd process. , (D) indicate the state of the fourth step.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The carbon dioxide separation and recovery device (hereinafter referred to as CO ₂ recovery device) according to the present embodiment can be mounted on a vehicle because it is small and lightweight, and can sufficiently separate carbon dioxide contained in the exhaust gas of an internal combustion engine. be. _{Therefore, the CO 2} recovery device according to the present embodiment will be described below with reference to an example applied to a vehicle equipped with a carbon recycling system that separates, recovers, and reuses carbon dioxide.

FIG. 1 is a diagram showing a configuration of a vehicle V equipped with a carbon recycling system S according to the present embodiment. The vehicle V is equipped with an internal combustion engine 1 (hereinafter referred to as “engine”) that converts thermal energy generated by burning liquid hydrocarbon fuel into mechanical energy, and utilizes the mechanical energy obtained by this engine 1. It travels by driving the drive wheels (not shown).

The vehicle V includes an engine 1, a fuel supply device 2 for supplying fuel to the engine 1, a CO _{2 recovery device 3 for recovering carbon dioxide (CO 2} ) from the exhaust flowing through the exhaust pipe 16 of the engine 1, and an exhaust pipe 16. _{Hydrogen (H 2} ) is added to the exhaust purification device 4 that purifies the exhaust flowing through the reactor 5, the reactor 5 that produces a synthetic gas _{containing methanol (CH 3} OH) from the carbon dioxide recovered by the _{CO 2 recovery device 3, and the reactor 5.} A hydrogen supply device 6 for supplying hydrogen and a condenser 7 for recovering methanol from the synthetic gas discharged from the reactor 5 are provided. The carbon recycling system S is composed of the CO ₂ recovery device 3, the reactor 5, the hydrogen supply device 6, and the condenser 7.

The engine 1 is rotated by, for example, a plurality of cylinders, a piston reciprocatingly provided in each cylinder, a spark plug provided in a combustion chamber partitioned by the piston in each cylinder, and a reciprocating motion of the piston. It is a multi-cylinder reciprocating engine equipped with a crankshaft. These spark plugs ignite in response to a command from a control device (not shown) to burn a mixture of fuel and air supplied into each cylinder.

The intake pipe 15 is a pipe that connects the intake port communicating with each cylinder of the engine 1 to the outside of the vehicle and guides the air outside the vehicle to each cylinder. The exhaust pipe 16 is a pipe that connects the exhaust port communicating with each cylinder of the engine 1 to the outside of the vehicle. _{The exhaust pipe 16 is provided with an exhaust purification device 4 and a CO 2} recovery device 3 in this order from the exhaust upstream side to the downstream side. The exhaust gas generated by burning the air-fuel mixture in each cylinder of the engine 1 is discharged to the outside of the vehicle via the _{exhaust purification device 4 and the CO 2 recovery device 3.}

The fuel supply device 2 includes a fuel tank 20 for storing fuel, a fuel injection valve 21 provided at an intake port communicating with each cylinder of the engine 1, and a fuel supply pipe connecting the fuel tank 20 and the fuel injection valve 21. 24 and.

The fuel tank 20 stores a liquid hydrocarbon fuel such as gasoline, methanol, or a mixed fuel obtained by mixing these gasoline and methanol. The fuel supply pipe 24 compresses the fuel stored in the fuel tank 20 by a high-pressure pump (not shown) and supplies the fuel to the fuel injection valve 21. The fuel injection valve 21 opens in response to a command from a control device (not shown) to inject fuel supplied from the fuel supply pipe 24. The air-fuel mixture in which the fuel injected from the fuel injection valve 21 and the air supplied from the intake pipe 15 are mixed is supplied into each cylinder of the engine 1.

The exhaust purification device 4 includes an exhaust purification catalyst (for example, a three-way catalyst), and under the action of the exhaust purification catalyst, unburned hydrocarbons (HC) and carbon monoxide (CO) contained in the exhaust of the engine 1. And purify nitrogen oxides (NOx) and the like.

The CO ₂ recovery device 3 is connected to the reactor 5 by _{a CO 2 pipe 31.} The CO ₂ recovery device 3 recovers carbon dioxide from the exhaust gas flowing through the exhaust pipe 16 and supplies it to the reactor 5 via the _{CO 2 pipe 31.} More specifically, the CO ₂ recovery device 3 separates the exhaust gas flowing through the exhaust pipe 16 into a recovery gas containing carbon dioxide as a main _{component and a CO 2 exhaust gas containing nitrogen (N 2} ) as a main component. , The recovered gas is _{discharged to the CO 2} pipe 31, and the CO ₂ exhaust gas is discharged to the outside of the vehicle through a tail pipe (not shown).

The CO ₂ recovery device 3 includes a carbon dioxide separation mechanism having a carbon dioxide separation structure that selectively permeates carbon dioxide in the exhaust gas flowing through the exhaust pipe 16. The CO ₂ recovery device 3 separates the exhaust gas of the engine 1 into a recovery gas and a CO ₂ de-CO 2 exhaust gas by using this carbon dioxide separation mechanism. The _{details of the CO 2} recovery device 3 and the carbon dioxide separation structure will be described in detail later.

Hydrogen supply device 6 includes a high pressure _{H 2} tank 61 for storing high-pressure hydrogen, with _{H 2} pipe 63 connecting the high pressure _{H 2} tank 61 and the reactor 5, a regulator 64 provided in _{H 2} pipe 63, the Be prepared. Regulator 64 depressurizes the hydrogen stored in the high pressure H ₂ tank 61 to a predetermined pressure and supplies it to the reactor 5 via of H ₂ pipe 63.

The hydrogen supply device 6 of the present embodiment is not limited to the case of supplying hydrogen stored in the high-pressure H ₂ tank 61 to reactor 5. The hydrogen supply device 6 may be configured to supply hydrogen generated from water by, for example, an electrolytic device to the reactor 5, or may be configured to supply hydrogen generated from ammonia to the reactor 5.

The reactor 5 reduces carbon dioxide by hydrogenating carbon dioxide contained in the recovered gas supplied from _{the CO 2 pipe 31 and hydrogen supplied from the H 2} pipe 63 at a predetermined ratio in the reaction cylinder. Synthesize methanol with.

More specifically, the reactor 5 includes a reaction cylinder into which the recovered gas supplied from _{the CO 2 pipe 31 is introduced, an H 2 injector that injects hydrogen supplied from the H 2} pipe 63 into the reaction cylinder, and the like. A carbon dioxide reduction catalyst provided in the reaction cylinder, a heating device for raising the temperature of the gas in the reaction cylinder, a compression device for compressing the gas in the reaction cylinder, and a synthetic gas connecting the reaction cylinder and the condenser 7. A pipe 51 is provided.

The carbon dioxide reduction catalyst reduces carbon dioxide in the presence of carbon dioxide and hydrogen and promotes the hydrogenation reaction of carbon dioxide that produces methanol. As the carbon dioxide reduction catalyst, a known catalyst such as a copper-zinc oxide catalyst is used.

The heating device uses the waste heat of the engine 1, that is, a part of the heat energy generated by burning the fuel in the engine 1, to promote the hydrogenation reaction of the carbon dioxide in the gas in the reaction cylinder. Raise the temperature to the required temperature. The compressor uses a part of the mechanical energy obtained by burning the fuel in the engine 1, more specifically, the power of the crankshaft of the engine 1, to promote the methanol synthesis reaction with the gas in the reaction cylinder. Compress to the required pressure to allow.

In the reactor 5 as described above, a _{predetermined amount of recovered gas is introduced into the reaction cylinder from the CO 2} pipe 31, and hydrogen measured so that the ratio of carbon dioxide and hydrogen in the reaction cylinder becomes a predetermined ratio is H ₂ injector. Is injected into the reaction cylinder, and the gas in the reaction cylinder is heated and compressed by a heating device and a compression device. As a result, the hydrogenation reaction of carbon dioxide (see the following formula (1)) proceeds under the action of the carbon dioxide reduction catalyst in the reaction cylinder, and methanol is produced. At the same time, due to the action of this carbon dioxide reduction catalyst, a reverse water-gas shift reaction (see formula (2) below) and a hydrogenation reaction of carbon monoxide (see formula (3) below) also proceed, and a synthetic gas containing methanol is also allowed to proceed. Is generated.
CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O (1)
CO ₂ + H ₂ → CO + H ₂ O (2)
CO + 2H ₂ → CH ₃ OH (3)

The synthetic gas generated in the reaction cylinder by the above procedure is supplied to the condenser 7 via the synthetic gas pipe 51. The synthetic gas discharged from the synthetic gas pipe 51 includes unreacted carbon dioxide, nitrogen mixed in the recovered gas that could not be separated by the _{CO 2} recovery device 3, and the like, in addition to methanol produced by the above-mentioned methanol synthesis reaction. ..

The condenser 7 recovers methanol from the syngas supplied from the reactor 5 and supplies it to the fuel tank 20. More specifically, the condenser 7 condenses the synthetic gas discharged from the reactor 5 by heat exchange, so that the liquid phase containing methanol as the main component and the gas containing unreacted carbon dioxide and nitrogen as the main components are used. Separated from the phase, the liquid phase is discharged from the liquid phase port, and the gas phase is discharged from the gas phase port.

The liquid phase port of the condenser 7 and the fuel tank 20 are connected by a liquid phase pipe 71. Therefore, the liquid phase discharged from the liquid phase port of the condenser 7 is guided into the fuel tank 20 by the liquid phase pipe 71. Further, the gas phase port of the condenser 7 and the exhaust gas purification device 4 and the CO ₂ recovery device 3 of the exhaust pipe 16 are connected by a gas phase pipe 72. Therefore, the gas phase discharged from the gas phase port of the condenser 7 is guided to the _{CO 2 recovery device 3 by the gas phase pipe 72.}

The flow of carbon in the vehicle V equipped with the carbon recycling system S as described above will be described. First, when the mixture of the hydrocarbon fuel stored in the fuel tank 20 and the air introduced from the intake pipe 15 is burned in the engine 1, the exhaust containing nitrogen, carbon dioxide, and water as the main components is produced in the engine 1. Is discharged from. Further, the carbon dioxide in the exhaust gas _{is recovered by the CO 2} recovery device 3 and supplied to the reactor 5. In the reactor 5, a methanol-containing syngas is produced by reacting carbon dioxide with hydrogen. Methanol in this syngas is recovered by the condenser 7 and stored in the fuel tank 20 as fuel. The unreacted carbon dioxide contained in the synthetic gas is _{recovered again by the CO 2} recovery device 3 and supplied to the reactor 5. In this way, the vehicle V equipped with the carbon recycling system S takes in carbon dioxide from the outside air _{and circulates carbon in the fuel tank 20, the engine 1, the CO 2} recovery device 3, the reactor 5, and the condenser 7. , Reduce carbon dioxide emissions from the tail pipe to the outside of the vehicle.

Next, _{the configuration of the CO 2} recovery device 3 will be described in detail with reference to FIG. FIG. 2 is a block diagram showing the configuration _{of the CO 2 recovery device 3.} As shown in FIG. 2, the CO ₂ recovery device 3 includes a compressor 17, a carbon dioxide separation mechanism 300 arranged in at least four rows, and a control unit 9 that controls the compressor 17 and the carbon dioxide separation mechanism 300. , Is equipped.

The compressor 17 compresses the carbon dioxide-containing exhaust gas discharged from the engine 1 and supplies it to at least one of the four rows of carbon dioxide separation mechanisms 300. That is, the compressor 17 applies the supply pressure of the exhaust gas to the carbon dioxide separation mechanism 300.

Each of the carbon dioxide separation mechanisms 300 in at least four rows separates the carbon dioxide contained in the exhaust gas compressed by the compressor 17 by the carbon dioxide adsorption and desorption reaction by the lithium composite oxide layer 34 described later. do. These at least four rows of carbon dioxide separation mechanisms 300 are provided in parallel with one compressor 17, and are controlled by the control unit 9 at different timings.

Specifically, the carbon dioxide separation mechanism 300 includes a carbon dioxide separation structure 30, a first flow path 310, a first valve 320, a second flow path 350, a second valve 340, and a third flow path 360. It has a third valve 370, a fourth flow path 380, a fourth valve 390, and an expander 18.

Here, the configuration of the carbon dioxide separation structure 30 will be described in detail with reference to FIGS. 3 and 4. FIG. 3 is a perspective view showing the configuration of the carbon dioxide separation structure 30. FIG. 4 is an enlarged view of the thin film layer 35 constituting the carbon dioxide separation structure 30. Specifically, FIG. 4 is an enlarged view of the thin film layer 35 when viewed from the X direction of FIG.

As described above, the carbon dioxide separation structure 30 is provided in the carbon dioxide separation mechanism 300 having a four-row structure _{included in the CO 2 recovery device 3.} The carbon dioxide separation structure 30 is formed in a rectangular parallelepiped shape, for example, and is arranged so that its longitudinal direction is along the flow direction of the exhaust gas. Such a carbon dioxide separation structure 30 is configured by arranging a plurality of (for example, 5 × 5) laminated bodies 36 having a rectangular parallelepiped shape in parallel. The arrangement pattern, that is, the number of vertical laminates 36 and the number of horizontal laminates is not particularly limited, and various arrangement patterns can be adopted depending on the flow rate of exhaust gas and the like.

The laminated body 36 is formed by laminating a plurality of thin film layers 35 in a predetermined direction with a gap. As shown in FIG. 4, the thin film layers 35 are laminated with adjacent thin film layers 35 having gaps in the direction orthogonal to the exhaust flow direction (X direction in FIG. 4). It is preferable that the plurality of gaps are evenly spaced, and the gaps may be sufficient to allow exhaust gas to flow in. However, if the gaps are too wide, the contact probability between the gas and the laminate will decrease, so the size of the gaps should be large. Set the value as small as possible within the range where the exhaust inflow resistance does not become too large.

The thin film layer 35 has a silicon thin film substrate 32 that generates heat by energization due to doping with impurities, and a lithium composite oxide layer 34 provided on the silicon thin film substrate 32 and made of a lithium composite oxide. Preferably, as shown in FIG. 5, a silica layer 33 made of silica is provided between the silicon thin film substrate 32 and the lithium composite oxide layer 34. More preferably, the silica layer 33 and the lithium composite oxide layer 34 are laminated on both sides of the silicon thin film substrate 32 in this order from the silicon thin film substrate 32 side. As a result, the lithium composite oxide layer 34 is arranged on both sides of the thin film layer 35, so that the reaction surface area can be increased. The film thickness of the thin film layer 35 should be as small as possible in order to reduce the heat capacity, but since the thickness of the thin film layer that can be realized in the manufacturing process is sufficiently thin, the carbon dioxide separation structure is a structure composed of the thin film layer 35. Make it as thin as possible within the range where the strength of the body 30 is maintained. For example, it is 10 μm or the like.

As the silicon thin film substrate 32, for example, a p-type silicon thin film substrate obtained by doping a silicon single crystal thin film substrate with impurities can be used. Such a silicon thin film substrate 32 has a property of instantaneously raising the temperature when energized by the control unit 9 described above. Further, since the silicon thin film substrate 32 of the present embodiment is a thin film, rapid heating and natural quenching are possible because the heat capacity is small.

As the lithium composite oxide layer 34, for example, a Li ₄ SiO ₄ thin film layer can be used. Such a lithium composite oxide has carbon dioxide adsorption / desorption characteristics, and such carbon dioxide adsorption / desorption depends on temperature. Specifically, when the temperature is below the predetermined temperature, carbon dioxide in the exhaust gas is selectively adsorbed by chemical adsorption, and when the temperature exceeds the predetermined temperature, the adsorbed carbon dioxide is desorbed and released. The film thickness of the lithium composite oxide layer 34 may be a value sufficiently smaller than the size of the gap between adjacent thin film layers 35 and a value sufficiently larger than the size of the carbon dioxide molecules, that is, for example, 0.1 μm. It is ~ 5 μm, and can have a film thickness of, for example, 1 μm.

The lithium composite oxide layer 34 is formed by thinly slicing a generally available Si substrate _{, dissolving Li 2} CO ₃ (lithium carbonate fine powder: melting point 723 ° C.) in ethanol, for example, and applying the thin layer in the presence of oxygen. _{The SiO 2} film and the Li ₄ SiO ₄ layer can be formed at the same time by heating with. The Li ₄ SiO ₄ film thickness is controllable because it depends on the oxygen concentration at the time of film formation.

As the silica layer 33, for example, a single crystal thin film of silica can be used. The silica layer 33 insulates the lithium composite oxide layer 34 from the energized silicon thin film substrate 32. The silica layer 33 is formed by a conventionally known semiconductor process.

The carbon dioxide separation structure 30 having the above configuration is compressed by the compressor 17, and the carbon dioxide produced by the lithium composite oxide layer 34 is charged with respect to the exhaust gas supplied from the compressor 17 via the first flow path 310. Carbon dioxide contained in the exhaust gas is separated by the adsorption / desorption reaction. Further, the carbon dioxide separation structure 30 supplies the recovered gas containing the separated carbon dioxide as a main component to the engine 1 via the second flow path 350 and the fourth flow path 380. Further, the carbon dioxide separation structure 30 brings the de-CO _{2 exhaust gas containing nitrogen (N 2} ), in which carbon dioxide is separated from the exhaust gas, as a main component, to the atmosphere via the second flow path 350 and the third flow path 360. Discharge.

Returning to FIG. 2, the first flow path 310 connects the compressor 17 and the carbon dioxide separation structure 30. The first flow path 310 supplies the exhaust gas compressed by the compressor 17 to the carbon dioxide separation structure 30. That is, the first flow path 310 guides the carbon dioxide-containing exhaust gas to the carbon dioxide separation structure 30.

The first valve 320 is provided in the first flow path 310 and opens and closes the first flow path 310. As a result, the inflow of exhaust gas into the carbon dioxide separation mechanism 300 is controlled. The first flow path 310 on the upstream side of the first valve 320 is branched into at least four branch flow paths, and is connected to each carbon dioxide separation mechanism 300 arranged in at least four rows. This makes it possible to supply exhaust gas to each carbon dioxide separation mechanism 300.

The second flow path 350 connects the carbon dioxide separation structure 30 and the third flow path 360, and also connects the carbon dioxide separation structure 30 and the fourth flow path 380. The second flow path 350 supplies carbon dioxide separated by the carbon dioxide separation structure 30 to the engine 1 via the fourth flow path 380, and de-CO ₂ exhaust gas is supplied to the atmosphere via the third flow path 360. To discharge.

The second valve 340 is provided in the second flow path 350 and adjusts the flow rate of the second flow path 350. That is, the second valve 340 adjusts the back pressure of the carbon dioxide separation structure 30.

_{The third flow path 360 releases the de-CO 2} exhaust gas separated by the carbon dioxide separation structure 30 and passing through the second flow path 350 to the atmosphere. That is, the third flow path 360 guides the _{CO 2 exhaust gas from the second flow path 350.}

The third valve 370 is provided in the third flow path 360, and opens and closes the third flow path 360. As a result, the _{emission of the de-CO 2} exhaust gas to the exhaust gas is controlled.

The fourth flow path 380 supplies carbon dioxide separated by the carbon dioxide separation structure 30 and passing through the second flow path 350 to the engine 1. That is, the fourth flow path 380 guides carbon dioxide from the second flow path 350.

The fourth valve 390 is provided in the fourth flow path 380 and opens and closes the fourth flow path 380. As a result, the recovery of carbon dioxide and the supply to the engine 1 are controlled.

The expander 18 is provided on the downstream side of the second valve 340 in the second flow path 350, and applies a negative pressure in the second flow path 350. That is, the expander 18 makes it possible to recover the carbon dioxide separated by the carbon dioxide separation mechanism 300.

The carbon dioxide separation mechanism 300 is arranged in at least four rows. This is because, as will be described later, the carbon dioxide separation mechanism 300 requires four steps as the processing steps for separating carbon dioxide, so that at least four rows of carbon dioxide separation mechanisms 300 are required to allow the four steps to proceed simultaneously. By need.

The control unit 9 controls the compressor 17, the first valve 320, the second valve 340, the expander 18, the third valve 370, and the fourth valve 390, all of which will be described later in the first step and the second. The carbon dioxide separation mechanism 300 is controlled so that the four steps of the step, the third step, and the fourth step are repeated in order. The control unit 9 shifts the timing of each of the four steps of the carbon dioxide separation mechanism 300 of at least four rows to execute. As a result, one of the carbon dioxide separation mechanisms 300 is always executing the first step, and continuous treatment of exhaust gas is possible.

_{Here, the operation of the CO 2} recovery device 3 will be described in detail with reference to FIG. 5A and 5B are views _{for explaining the operation of the CO 2} recovery device, where FIG. 5A shows the state of the first step, FIG. 5B shows the state of the second step, and FIG. 5C shows the state of the third step. (D) shows the state of the fourth step. In FIG. 5, the valve displayed in white represents the open state, and the valve displayed in black represents the squeezed state or the closed state.

The first step shown in FIG. 5A is a step of supplying exhaust gas to the carbon dioxide separation structure 30 and adsorbing carbon dioxide by the lithium composite oxide layer 34. In this first step, the first valve 320 is opened to throttle the second valve 340, and the third valve 370 is opened to close the fourth valve 390. As a result, the exhaust gas compressed by the compressor 17 is supplied to the carbon dioxide separation structure 30 via the first flow path 310, and the carbon dioxide contained in the exhaust gas is adsorbed by the lithium composite oxide layer 34 and separated. NS.

The second step shown in FIG. 5B is a step of releasing the _{CO 2} exhaust gas from the carbon dioxide separation structure 30 to the atmosphere. In this second step, the first valve 320 is closed to open the second valve 340, and the third valve 370 is opened to close the fourth valve 390. _{As a result, the de-CO 2} exhaust gas from which carbon dioxide is separated from the exhaust gas is released to the atmosphere through the third flow path 360. Since the first valve 320 is closed in this second step, the exhaust gas discharged from the engine 1 passes through the branch flow path of the first flow path 310 and is executing the above-mentioned first step. It is supplied to the carbon dioxide separation mechanism 300.

The third step shown in FIG. 5C is a step of desorbing and recovering carbon dioxide from the carbon dioxide separation structure 30 by rapidly heating the carbon dioxide separation structure 30. In this third step, the first valve 320 is closed to open the second valve 340, the third valve 370 is closed to open the fourth valve 390, and the pressure is sucked by the expander 18 to be negative in the second flow path 350. Apply pressure. At the same time, the temperature is instantaneously raised by energizing the silicon thin film substrate 32, which will be described later, which constitutes the thin film layer 35 of the carbon dioxide separation structure 30. As a result, the carbon dioxide desorbed from the lithium composite oxide layer 34 flows into the second flow path 350 and the fourth flow path 380 as a negative pressure is applied to the second flow path 350 by suction by the expander 18. It is supplied to the engine 1 via. In this third step, since the first valve 320 is closed as in the second step, the exhaust gas discharged from the engine 1 passes through the branch flow path of the first flow path 310 and is described in the first step. Is being supplied to another carbon dioxide separation mechanism 300 that is running.

The fourth step shown in FIG. 5D is a step of naturally quenching the carbon dioxide separation structure 30. In this fourth step, the first valve 320 is closed to open the second valve 340, and the third valve 370 is closed to open the fourth valve 390. At this time, since the lithium composite oxide layer 34 is a thin film and has a small heat capacity, it can be rapidly cooled naturally. Carbon dioxide is desorbed from the lithium composite oxide layer 34 following the third step until the temperature of the lithium composite oxide layer 34 is sufficiently lowered, and the desorbed carbon dioxide is used in the second flow path 350 and the fourth flow. It is supplied to the engine 1 via the road 380. By lowering the temperature of the lithium composite oxide layer 34 in the fourth step, carbon dioxide can be adsorbed again in the next first step. In the fourth step, since the first valve 320 is closed as in the second step and the third step, the exhaust gas discharged from the engine 1 passes through the branch flow path of the first flow path 310 and is described above. It is supplied to another carbon dioxide separation mechanism 300 that is executing the first step of the above.

The above four steps are repeatedly executed under the control of the control unit 9. As described above, the control unit 9 enables continuous processing of carbon dioxide separation by executing the steps of each of the four steps of the carbon dioxide separation mechanism 300 in at least four rows at different timings.

Specifically, in the control unit 9, when the first carbon dioxide separation mechanism 300 executes the first step, the second carbon dioxide separation mechanism 300 executes the second step and the third carbon dioxide dioxide is executed. Each carbon dioxide separation mechanism 300 is controlled so that the carbon separation mechanism 300 executes the third step and the fourth carbon dioxide separation mechanism 300 executes the fourth step.

Further, in the control unit 9, when the first carbon dioxide separation mechanism 300 executes the second step, the second carbon dioxide separation mechanism 300 executes the third step, and the third carbon dioxide Each carbon dioxide separation mechanism 300 is controlled so that the separation mechanism 300 executes the fourth step and the fourth carbon dioxide separation mechanism 300 executes the first step.

Further, in the control unit 9, when the first carbon dioxide separation mechanism 300 executes the third step, the second carbon dioxide separation mechanism 300 executes the fourth step, and the third carbon dioxide Each carbon dioxide separation mechanism 300 is controlled so that the separation mechanism 300 executes the first step and the fourth carbon dioxide separation mechanism 300 executes the second step.

Further, in the control unit 9, when the first carbon dioxide separation mechanism 300 executes the fourth step, the second carbon dioxide separation mechanism 300 executes the first step and the third carbon dioxide. Each carbon dioxide separation mechanism 300 is controlled so that the separation mechanism 300 executes the second step and the fourth carbon dioxide separation mechanism 300 executes the third step.

According to this embodiment, the following effects are achieved.
_{In the CO 2} recovery device 3 of the present embodiment, carbon dioxide in the exhaust is removed by controlling the first valve 320, the second valve 340, the third valve 370, and the fourth valve 390 that constitute the carbon dioxide separation mechanism 300. The first step of adsorbing to the lithium composite oxide layer 34, the second step of releasing carbon dioxide exhaust, and the temperature rise of the lithium composite oxide layer 34 to desorb carbon dioxide from the lithium composite oxide layer. The configuration is such that the four steps of the third step of recovering and the fourth step of lowering the temperature of the lithium composite oxide layer 34 are repeatedly executed in this order. As a result, the lithium composite oxide layer 34 having the property of adsorbing and desorbing carbon dioxide can efficiently perform selective chemisorption, separation, and recovery of carbon dioxide. Further, since the lithium composite oxide layer 34 is used, the apparatus can be miniaturized. _{Therefore, according to the CO 2} recovery device 3 of the present embodiment, the carbon dioxide that can be mounted on the vehicle V and contained in the exhaust gas of the engine 1 can be sufficiently separated and recovered.

Further, in the CO ₂ recovery device 3 of the present embodiment, by shifting the execution timing of the four steps among at least four carbon dioxide separation mechanisms 300, one of the carbon dioxide separation mechanisms 300 always executes the first step. Controlled to do. As a result, the exhaust gas discharged from the engine 1 can always be introduced into any of the carbon dioxide separation mechanisms 300, and carbon dioxide can be continuously separated and recovered. _{Therefore, according to the CO 2} recovery device 3 of the present embodiment, it can be preferably used for vehicle mounting where continuous separation and recovery of carbon dioxide are required.

_{Further, the CO 2} recovery device 3 of the present embodiment is configured to include a compressor 17. As a result, the compressor 17 can apply a positive pressure to the first flow path 310, so that the supply pressure to the carbon dioxide separation mechanism 300 can be applied to the exhaust gas discharged from the engine 1. , Carbon dioxide can be separated and recovered more efficiently.

Further, in the CO ₂ recovery device 3 of the present embodiment, the carbon dioxide separation mechanism 300 has an expander 18. As a result, a negative pressure can be applied to the second flow path 350 by suction by the expander 18, so that carbon dioxide adsorbed on the lithium composite oxide layer 34 can be positively desorbed.

Further, the carbon dioxide separation structure 30 of the present embodiment is configured to include a thin film layer 35 having a silicon thin film substrate 32 that generates heat by energization due to doping with impurities, and a lithium composite oxide layer 34. As a result, the lithium composite oxide having carbon dioxide adsorption / desorption characteristics is formed as a thin film having an extremely small heat capacity, so that it can be miniaturized and has an extremely fast response in the temperature-dependent adsorption / desorption reaction of carbon dioxide. Properties can be obtained, and carbon dioxide can be efficiently adsorbed and desorbed. Further, since the silicon thin film substrate 32 which is doped with impurities and instantaneously raises the temperature by energization is provided, the carbon dioxide separation structure 30 can be rapidly heated, and since it is a thin film, natural quenching is also possible. Dependent carbon dioxide can be adsorbed and desorbed more efficiently. Therefore, according to the carbon dioxide separation structure 30 of the present embodiment, the carbon dioxide that can be mounted on the vehicle V and contained in the exhaust gas of the engine 1 can be sufficiently separated and recovered.

Further, in the carbon dioxide separation structure 30 of the present embodiment, a silica layer 33 made of silica is provided between the silicon thin film substrate 32 and the lithium composite oxide layer 34. As a result, the silica layer 33 is interposed between the silicon thin film substrate 32 and the lithium composite oxide layer 34, so that the lithium composite oxide layer 34 can be insulated from the energized silicon thin film substrate 32. Therefore, the lithium composite oxide layer 34 can be protected from the influence of energization.

Further, in the carbon dioxide separation structure 30 of the present embodiment, the thin film layer 35 formed by laminating the silica layer 33 and the lithium composite oxide layer 34 on both sides of the silicon thin film substrate 32 in this order from the silicon thin film substrate 32 side. The configuration is provided with. As a result, the lithium composite oxide layers 34 are arranged on both sides of the silicon thin film substrate 32, so that carbon dioxide can be adsorbed and desorbed more efficiently.

Further, in the carbon dioxide separation structure 30 of the present embodiment, the carbon dioxide separation structure 30 is constructed by arranging a plurality of laminated bodies 36 in which a plurality of thin film layers 35 are laminated with a gap in parallel. As a result, the thin film layer 35 can be multi-layered to increase the area, and exhaust gas can flow through the gaps, so that carbon dioxide can be adsorbed and desorbed more efficiently. Further, the carbon dioxide separation structure 30 can be composed of a number of laminated bodies 36 corresponding to the flow rate of the exhaust gas, and the carbon dioxide separation structure 30 can be designed according to the flow rate of the exhaust gas.

The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

For example, in the above embodiment, the carbon dioxide separation structure 30 is composed of a thin film layer 35 having a silicon thin film substrate 32 that generates heat when energized by doping with impurities, and lithium composite oxidation is performed by energizing the silicon thin film substrate 32. The structure is such that the temperature of the material layer 34 is raised, but the temperature is not limited to this. For example, the lithium composite oxide layer 34 may be heated by a heating means such as a heater.

1 Engine 3 CO ₂ recovery device (carbon dioxide separation recovery device)
9 Control unit 17 Compressor 18 Expander 30 Carbon dioxide separation structure 32 Silicon thin film substrate 33 Silica layer 34 Lithium composite oxide layer 35 Thin film layer 36 Laminated body 300 Carbon dioxide separation mechanism 310 1st flow path 320 1st valve 350th 2 flow path 340 2nd valve 360 3rd flow path 370 3rd valve 380 4th flow path 390 4th flow path

Claims (5)

A carbon dioxide separation and recovery device that separates and recovers carbon dioxide contained in the exhaust gas of an internal combustion engine.
A carbon dioxide separation structure having a lithium composite oxide layer made of a lithium composite oxide,
A first flow path that guides exhaust gas to the carbon dioxide separation structure, a first valve that opens and closes the first flow path, and
A second flow path that guides carbon dioxide separated by the carbon dioxide separation structure and decarbon dioxide exhaust, and a second valve that regulates the flow rate of the second flow path,
A third flow path that guides decarbonization exhaust from the second flow path, a third valve that opens and closes the third flow path, and
A carbon dioxide separation mechanism having a fourth flow path for guiding carbon dioxide from the second flow path and a fourth valve for opening and closing the fourth flow path.
A first valve in which carbon dioxide contained in exhaust gas is adsorbed on the lithium composite oxide layer by opening the first valve to throttle the second valve and opening the third valve to close the fourth valve. Process and
A second step in which the decarbonized exhaust is guided and discharged through the third flow path by closing the first valve and opening the second valve and opening the third valve and closing the fourth valve. ,
From the lithium composite oxide layer by closing the first valve and opening the second valve, closing the third valve and opening the fourth valve, and raising the temperature of the lithium composite oxide layer. The third step of desorbing carbon dioxide and guiding it through the fourth flow path to recover it.
The fourth step of closing the first valve and opening the second valve, closing the third valve, opening the fourth valve, and lowering the temperature of the lithium composite oxide layer is repeatedly executed in this order. A carbon dioxide separation / recovery device including a control unit that controls the carbon dioxide separation mechanism. At least four carbon dioxide separation mechanisms are provided and arranged in parallel.
The control unit shifts the execution timing of the four steps among at least four of the carbon dioxide separation mechanisms so that the carbon dioxide separation mechanism always executes the first step. The carbon dioxide separation and recovery device according to claim 1, which controls each of the carbon separation mechanisms. The carbon dioxide separation and recovery device according to claim 1 or 2, which is provided on the upstream side of the first flow path and includes a compressor that applies positive pressure to the first flow path. The carbon dioxide separation and recovery device according to any one of claims 1 to 3, wherein the carbon dioxide separation mechanism has an expander that applies a negative pressure in the second flow path. The carbon dioxide separation structure is
A silicon thin film substrate that generates heat when energized due to doping with impurities,
The carbon dioxide separation and recovery apparatus according to any one of claims 1 to 4, further comprising a thin film layer having the lithium composite oxide layer provided on the silicon thin film substrate.

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