Carbon dioxide collection system

Abstract

To provide a carbon dioxide collection system in which a heat radiation effect of an adsorbent is high, and which increases processing efficiency.SOLUTION: A carbon dioxide collection system includes: an adsorption apparatus 2 for causing an adsorbent to adsorb carbon dioxide contained in air; an air supply path for supplying air to the adsorption apparatus 2; a heating / cooling apparatus for heating or cooling the adsorbent; and a recovery path for recovering the carbon dioxide adsorbed in the adsorbent of the adsorption apparatus 2. The adsorption apparatus 2 comprises a fin tube type heat exchanger 20. On an exterior surface of the fin tube type heat exchanger 20, an adsorbent is carried. The adsorbent is heated or cooled according to supply of a heating medium or a cooling medium from the heating / cooling apparatus to the fin tube type heat exchanger 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide capture system that captures carbon dioxide contained in air. [Background technology]

[0002] Global warming caused by carbon dioxide released during the combustion of fossil fuels has become a problem, and there is an urgent need to curb the release of carbon dioxide into the atmosphere as a result of fossil fuel combustion. On the other hand, there are applications where the use of fossil fuels is technically or economically unavoidable, and so there are growing expectations for technology called Direct Air Capture, which directly captures carbon dioxide from the atmosphere.

[0003] Carbon dioxide can be converted into hydrocarbons such as methane by reacting it with hydrogen. If the hydrogen is produced using electricity derived from renewable energy sources such as solar or wind power, and the carbon dioxide is collected from the atmosphere, the resulting hydrocarbons, even when burned, will not increase the atmospheric carbon dioxide concentration throughout the entire process from fuel production to use, making them carbon-neutral hydrocarbons.

[0004] In conventional carbon dioxide capture systems, the following steps are generally repeated in sequence: an adsorption step in which carbon dioxide contained in the air is adsorbed onto an adsorbent in an adsorption device, a depressurization step in which the air pressure in the adsorption device is reduced to below atmospheric pressure, a desorption step in which the adsorbent is heated to desorb carbon dioxide, and a cooling step in which the adsorbent is cooled.This carbon dioxide capture system adsorbs carbon dioxide onto the adsorbent in the adsorption step, and then performs a depressurization step and a desorption step in which the adsorbent with adsorbed carbon dioxide is heated under reduced pressure to desorb the carbon dioxide from the adsorbent, thereby making it possible to capture high-concentration carbon dioxide.

[0005] As such a conventional carbon dioxide recovery system, for example, as disclosed in Patent Document 1 below, a system equipped with an adsorption device having a carbon dioxide adsorption plate on which an amine compound is supported is known. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-13169 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional carbon dioxide capture systems, adsorbents, particularly those carrying an amine compound, are prone to oxidation and rapid deterioration when exposed to air in a heated state during the desorption step, so the adsorbent is cooled under reduced pressure after the desorption step. However, because heat dissipation is extremely slow under reduced pressure, it takes a long time for the adsorbent to cool to a predetermined temperature, leaving room for improvement in terms of improving treatment efficiency.

[0008] An object of the present invention is to provide a carbon dioxide recovery system in which the heat dissipation effect of the adsorbent is high and the treatment efficiency is high. [Means for solving the problem]

[0009] The carbon dioxide capture system according to the present invention is configured to include an adsorption device that adsorbs carbon dioxide contained in air onto an adsorbent, an air supply path that supplies air to the adsorption device, a heating / cooling device that heats or cools the adsorbent, and a capture path that captures the carbon dioxide adsorbed by the adsorbent of the adsorption device, The adsorption device includes a finned tube heat exchanger, the adsorbent is supported on the outer surface of the finned tube heat exchanger, and the adsorbent is heated or cooled by supplying a heating medium or a cooling medium from the heating / cooling device to the finned tube heat exchanger.

[0010] According to this configuration, by using a fin-tube heat exchanger as a substrate supporting the adsorbent, it is possible to efficiently cool the adsorbent even under reduced pressure, where heat dissipation is extremely slow. Furthermore, it is possible to efficiently heat the adsorbent in the desorption process. As a result, the processing time per cycle is shortened, thereby improving processing efficiency.

[0011] In the carbon dioxide recovery system according to the present invention, it is preferable that the heating medium is saturated steam or hot water, and the cooling medium is water.

[0012] According to this configuration, saturated steam or hot water is used as the heating medium, and water is used as the cooling medium, so there is no need to use a special medium, and the device configuration does not become complicated.

[0013] In the carbon dioxide recovery system according to the present invention, it is preferable that the heating / cooling device generates the heating medium by utilizing waste heat, geothermal heat, or solar heat.

[0014] According to this configuration, the heating medium is generated using renewable energy such as waste heat, geothermal heat, or solar heat, which promotes carbon neutrality.

[0015] In the carbon dioxide recovery system according to the present invention, it is preferable that the adsorbent is made of a porous material containing an amine compound.

[0016] According to this configuration, the adsorbent is made of a porous material containing an amine compound, so that carbon dioxide can be adsorbed more efficiently. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing the configuration of a carbon dioxide capture system. [Figure 2] FIG. 2 is a diagram showing the configuration of a suction device. [Figure 3] FIG. 2 is a partially enlarged view of the fin-tube heat exchanger. [Figure 4] FIG. 10 is a diagram showing the configuration of another embodiment of the carbon dioxide capture system. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Embodiment] Hereinafter, an embodiment of the present invention will be described. (Carbon dioxide capture system) As shown in Figure 1, the carbon dioxide capture system 1 includes an adsorption device 2 that adsorbs carbon dioxide contained in the air onto adsorbent material A, an air supply path 3 that supplies air to the adsorption device 2, an air discharge path 4 that discharges air from the adsorption device 2, a heating / cooling device 5 that heats or cools the adsorbent material A, and a capture path 6 that captures the carbon dioxide adsorbed by the adsorbent material A of the adsorption device 2.

[0019] In this embodiment, the air supply path 3 includes a blower 30 (such as a blower) and a first switching valve V1. The air discharge path 4 includes a second switching valve V2. The recovery path 6 includes a third switching valve V3, a condenser 60, and a pressure reducing device 61 (such as a vacuum pump).

[0020] The heating / cooling device 5 is connected to the adsorption device 2 via a pipe P that can supply a heating medium or a cooling medium to the adsorption device 2. The heating / cooling device 5 may be configured such that the heating device and the cooling device are separate entities, or may be a device that has both heating and cooling functions integrated into it. Examples of the heating device include an electric heater and a heat exchanger. It is desirable that the heating device is configured to generate the heating medium by utilizing waste heat, geothermal heat, or solar heat. Examples of the cooling device include a cooling water circulation device. Examples of a device that has both heating and cooling functions integrated into it include a heat pump 50.

[0021] Examples of the heating medium include hot water at a predetermined temperature, saturated steam, and superheated steam. Examples of the cooling medium include water (room temperature water, cold water, cooling water, etc.). When a heat pump is used as the heating / cooling device 5, the refrigerant used in the heat pump can be used as the heating or cooling medium as is. Examples of such refrigerants that can be used include HFC refrigerants such as R410A and R32, HFO refrigerants such as R1234yf, and hydrocarbon refrigerants such as propane.

[0022] 2 and 3, the adsorption device 2 includes a finned tube heat exchanger 20 therein. In this embodiment, the adsorbent A is supported on the outer surface of the fin portion 21 of the finned tube heat exchanger 20. A heating medium or a cooling medium from the heating / cooling device 5 is supplied to the tube portion 22 of the finned tube heat exchanger 20, thereby heating or cooling the adsorbent A.

[0023] The adsorbent A is a component capable of adsorbing and desorbing carbon dioxide contained in the air, and is preferably composed of a porous material containing an amine compound. By combining the amine compound with an appropriate carrier, carbon dioxide can be desorbed at a relatively low temperature. Examples of applicable amine compounds include tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI). Examples of porous materials include metal-organic frameworks (MOFs), zeolites, activated carbon, mesoporous silica, and alumina.

[0024] The adsorbent A may be supported not only on the fin portion 21 of the fin-tube heat exchanger 20 but also on the outer surface of the tube portion 22. Examples of a method for supporting the adsorbent A include a dip coating method and a spray coating method.

[0025] (Carbon dioxide capture method) Next, a carbon dioxide recovery method using the carbon dioxide recovery system 1 will be described with reference to FIG.

[0026] The carbon dioxide recovery method includes an adsorption process in which carbon dioxide contained in the air is adsorbed onto adsorbent A in adsorption device 2, a depressurization process in which the air pressure in adsorption device 2 is reduced to below atmospheric pressure, a desorption process in which adsorbent A is heated to desorb carbon dioxide, and a cooling process in which adsorbent A is cooled, and these processes are carried out repeatedly in sequence.

[0027] In the adsorption step, the first switching valve V1 and the second switching valve V2 are opened, and the third switching valve V3 is closed. At this time, the temperature inside the adsorption device 2 is approximately room temperature, and the pressure is approximately atmospheric pressure. By operating the blower 30, air flows into the adsorption device 2 through the air supply path 3, and at least a portion of the carbon dioxide is adsorbed by the adsorbent A. The air with a reduced carbon dioxide concentration is discharged from the adsorption device 2 through the air discharge path 4.

[0028] In the depressurization step, the first switching valve V1 and the second switching valve V2 are closed, and the third switching valve V3 is opened. Then, the depressurization device 61 is operated to remove air from the adsorption device 2. At this time, the temperature inside the adsorption device 2 is approximately room temperature, but the air pressure is below atmospheric pressure. The processing time of the depressurization step and the output of the depressurization device 61 may be set appropriately depending on the purity required for the carbon dioxide obtained in the subsequent desorption step. Also, in the depressurization step, the condenser 60 may be operated as needed to liquefy water vapor contained in the sucked air and discharge it as drain water.

[0029] In the desorption step, following the depressurization step, the first and second switching valves V1 and V2 are closed, and the third switching valve V3 is opened. Then, with the depressurization device 61 in operation, the heating / cooling device 5 is operated to supply a heating medium to the tube portion 22 of the finned tube heat exchanger 20 via the pipe P, thereby heating the adsorbent A. The heating temperature is a temperature suitable for desorption of carbon dioxide, preferably 60°C to 100°C. This allows high-concentration carbon dioxide to be recovered via the recovery path 6. The recovered carbon dioxide is, for example, filled into a cylinder or the like while being pressurized by a compressor as needed. Note that, in the desorption step as well, the condenser 60 may be operated as needed to liquefy water vapor contained in the sucked air and discharge the liquefied water as drain water.

[0030] In the cooling step, the first selector valve V1, the second selector valve V2, and the third selector valve V3 are all closed. Then, by operating the heating / cooling device 5, a cooling medium is supplied to the tube portion 22 of the finned tube heat exchanger 20 via the piping P to cool the adsorbent A. The cooling temperature is a temperature suitable for adsorbing carbon dioxide, preferably 10°C to 50°C. This allows the adsorbent A to be cooled under conditions where the oxygen partial pressure is low. Note that the air pressure inside the adsorption device 2 at this time is lower than atmospheric pressure.

[0031] [Another embodiment] 4, two systems of the above-described carbon dioxide capture system 1 may be prepared, and a heat pump 50 may be used as the heating / cooling device 5, so that each adsorption device 2 is heated or cooled by a single heat pump 50. In this case, one carbon dioxide capture system 1 performs a desorption step by heating the adsorbent A using the condensation heat of the heat pump 50, and the other carbon dioxide capture system 1 performs a cooling step by cooling the adsorbent A using the evaporation heat of the heat pump 50.

[0032] Furthermore, the configurations disclosed in the above embodiments can be applied in combination with configurations disclosed in other embodiments as long as no contradictions arise, and the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0033] The present invention can be suitably used in the technical field relating to an apparatus and method for recovering low-concentration carbon dioxide contained in the atmosphere to obtain high-purity carbon dioxide, for example. [Explanation of symbols]

[0034] 1. Carbon dioxide capture system 2 Adsorption device 20 Finned tube heat exchanger 21 Fin part 22 Tube part 3 Air supply path 30 Blower 4 Air exhaust route 5 Heating / cooling equipment 50 Heat Pump 6. Recovery route 60 Condenser 61 Pressure reducing device A. Adsorbent V1 First switching valve V2 Second switching valve V3 Third switching valve P piping

Claims

1. A carbon dioxide recovery system comprising: an adsorption device that adsorbs carbon dioxide contained in air onto an adsorbent; an air supply path that supplies air to the adsorption device; a heating / cooling device that heats or cools the adsorbent; and a recovery path that recovers the carbon dioxide adsorbed by the adsorbent of the adsorption device, a carbon dioxide recovery system, wherein the adsorption device includes a fin-tube heat exchanger, the adsorbent is supported on the outer surface of the fin-tube heat exchanger, and the adsorbent is heated or cooled by supplying a heating medium or a cooling medium from the heating / cooling device to the fin-tube heat exchanger.

2. The carbon dioxide recovery system according to claim 1, wherein the heating medium is saturated steam or hot water, and the cooling medium is water.

3. 3. The carbon dioxide recovery system according to claim 1, wherein the heating / cooling device generates the heating medium by utilizing waste heat, geothermal heat, or solar heat.

4. 3. The carbon dioxide recovery system according to claim 1, wherein the adsorbent is made of a porous material containing an amine compound.

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