Carbon dioxide adsorption / separation device

Abstract

To provide a carbon dioxide adsorption / separation device which can efficiently adsorb and separate carbon dioxide.SOLUTION: A carbon dioxide adsorption / separation device includes: a plasma treatment path 10 for making plasma act on gas to be treated containing carbon dioxide by introducing and circulating the gas to be treated therein; an adsorption treatment path 20 which is filled with a coal ash layer and stores the coal ash layer, circulates the gas to be treated on which the plasma acts in the coal ash layer by introduction of the gas to be treated, adsorbs the carbon dioxide contained in the gas to be treated to the coal ash layer, and separating the carbon dioxide from the gas to be treated; and a buffer tank 30 for introducing sending out the gas to be treated coming out of the adsorption treatment path 20 to the plasma treatment path 10 at the next stage at a predetermined pressure by introduction of the gas to be treated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a carbon dioxide adsorption and separation device, and particularly to a device capable of efficiently adsorbing and separating carbon dioxide.

Background Art

[0002] Reducing carbon dioxide emissions has attracted attention as a measure against global warming, and various carbon dioxide removal technologies are being developed in the industrial world.

[0003] For example, a method of separating carbon dioxide using a separation membrane is known (Patent Document 1, Patent Document 2), but the production of the membrane is very difficult.

[0004] Also, a method of adsorbing and separating carbon dioxide using an amine compound is known, but it is necessary to use chemicals.

[0005] Also, a method has been proposed in which steel slag powder mainly composed of calcium oxide is formed into a porous body, water is added to the porous molded body to promote the reaction between carbon dioxide and calcium oxide, and calcium carbonate is precipitated between the slag particles of the porous molded body to separate carbon dioxide (Non-Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in the method described in Non-Patent Document 1, the content of silicon dioxide and the like in the steel slag powder is high, and the content of calcium oxide is only about 40%. Therefore, the low content of calcium oxide is disadvantageous for the removal of carbon dioxide.

[0009] In view of this point, an object of the present invention is to provide a carbon dioxide adsorption and separation device that can efficiently adsorb and separate carbon dioxide.

Means for Solving the Problems

[0010] Therefore, the carbon dioxide adsorption and separation device according to the present invention includes a plasma treatment path in which a gas to be treated containing carbon dioxide is introduced and circulated, and plasma is applied to the gas to be treated; an adsorption treatment path filled with a coal ash layer, into which the gas to be treated subjected to the plasma treatment is introduced and circulated, and carbon dioxide contained in the gas to be treated is adsorbed by the coal ash layer and separated from the gas to be treated; and a buffer tank into which the gas to be treated exiting the adsorption treatment path is introduced and sent to the next-stage plasma treatment path at a predetermined pressure.

[0011] Here, FIG. 2 schematically shows the concept of adsorbing and separating carbon dioxide. Now, when the gas to be treated containing carbon dioxide is fed into the plasma treatment path 50 by a blower fan, a high voltage is applied in the plasma treatment path 50 to generate plasma in the gas to be treated, and the carbon dioxide in the gas to be treated is ionized and excited. The gas to be treated containing cations generated by the ionization of carbon dioxide and excited carbon dioxide is fed into the adsorption treatment path 51, passes through the coal ash layer in the adsorption treatment path 51, and the cations generated by the ionization of carbon dioxide and the excited carbon dioxide are adsorbed by the coal ash layer and fed into the plasma treatment path 50 in the next stage, where they are similarly plasma-treated and adsorbed and separated by the coal ash layer, and such treatment is repeated over a plurality of stages. At this time, since there is a concern that the capacity of the blower fan may be insufficient, a buffer tank is provided on the outlet side of the adsorption treatment furnace 51, and the gas to be treated is adjusted to a predetermined pressure by the buffer tank and sent out to the plasma treatment path in the next stage.

[0012] According to the amount of the gas to be treated to be processed, a combination of a plasma treatment path, an adsorption treatment path, and a buffer tank is used in one formula or a plurality of sets.

[0013] The flow path of the plasma treatment path can be configured between a cylindrical electrode and an axial electrode coaxially arranged inside the cylindrical electrode, and plasma can be applied to the gas to be treated by applying a high voltage between the cylindrical electrode and the axial electrode.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. FIG. 1 shows a preferred embodiment of a carbon dioxide adsorption and separation apparatus according to the present invention. In the figure, the carbon dioxide adsorption and separation apparatus 100 of this example includes a plasma treatment path 10, an adsorption treatment path 20 continuous with the downstream side of the plasma treatment path 10, and a buffer tank 30 continuous with the downstream side of the adsorption treatment path 20 as one set, and a plurality of sets, for example, 5 sets are continuously configured.

[0016] The plasma treatment path 10 is composed of a cylindrical electrode 11 and an axial electrode 12 arranged coaxially with the cylindrical electrode 11 inside the cylindrical electrode 11. The axial electrode 12 is held coaxially with the cylindrical electrode 11 by a plurality of insulating spacers 13, and an introduction path 15 for introducing a gas to be treated is provided in a flow path 14 formed by the cylindrical electrode 11 and the axial electrode 12.

[0017] The cylindrical electrode 11 of the plasma treatment path 10 is a cathode provided in a cylindrical surface shape on the inner circumference of a straight pipe body. The axial electrode 12 of the plasma treatment path 10 is an anode provided in a cylindrical surface shape on the outer circumference of a straight shaft body extending in the axial direction.

[0018] It is preferable to use seamless pipes without joints for the cylindrical electrode 11 and the axial electrode 12, and the material thereof is not particularly limited. For example, it may be a stainless steel pipe, or a conductive resin (CFRP: Carbon Fiber Reinforced Plastics) pipe reinforced with carbon such as graphite or carbon nanotube. Alternatively, it may be a pipe coated with a resin layer containing carbon such as graphite or carbon nanotube on the inner peripheral surface or the outer peripheral surface of a stainless steel pipe. Note that seamless stainless steel pipes are expensive, heavy, difficult to withstand high temperatures of 400°C or higher, and may be corroded by strong acids and strong alkalis. Therefore, conductive resin pipes are preferred.

[0019] The insulating spacer 13 can be formed of, for example, a fluororesin that is excellent in chemical resistance and heat resistance. The insulating spacer 13 is preferably formed in a substantially X shape or a substantially Y shape when viewed from the axial direction, for example, for coaxial centering, and is preferably configured with a frame as thin as possible so as not to obstruct the flow of the gas to be processed.

[0020] The flow path 14 of the plasma processing path 10 is formed between the inner circumference of the cylindrical electrode 11 and the outer circumference of the axial electrode 12, and extends in the axial direction with an annular flow path cross section.

[0021] When a high voltage of 13,000 V to 25,000 V is applied between the cylindrical electrode 11 and the axial electrode 12 by an electric circuit (not shown) connected to the cylindrical electrode 11 and the axial electrode 12, a discharge is generated between the cylindrical electrode 11 and the axial electrode 12. Since electrical energy is given to the gas to be processed flowing in the electric field of this discharge, plasma is generated in the gas to be processed. When plasma acts on the gas to be processed containing carbon dioxide, the carbon dioxide is ionized and excited. It is not necessary to add a gas for facilitating plasma generation to the gas to be processed, and it is better not to do so in consideration of the operation cost. For example, if a noble gas such as argon (Ar) gas or helium (He) gas is added to the gas to be processed and fed into the flow path 14, plasma is likely to be generated, but an expensive gas is used, which is not preferable.

[0022] Due to the discharge between the cylindrical facing surfaces of the cylindrical electrode 11 and the axial electrode 12, plasma is generated throughout the flow path 14. Therefore, while feeding the gas to be processed into the flow path 14, the gas to be processed is plasmaized up to the downstream end of the flow path 14, and continuous processing of quickly feeding it from the flow path 14 into the adsorption processing path 20 is possible.

[0023] Here, if there are irregularities on the cylindrical electrode 111 and the shaft-shaped electrode 12, spark discharge will occur at that location. When spark discharges such as corona discharge and glow discharge occur, plasma is generated only in the vicinity, and it is difficult to exert the effect of plasma treatment. Also, if the voltage applied between the cylindrical electrode 11 and the shaft-shaped electrode 12 is too high or the distance between the cylindrical electrode 11 and the shaft-shaped electrode 12 is too short, there is a possibility of spark discharge. The voltage of 23000V is the upper limit value for not generating spark discharge when the distance between the cylindrical electrode 11 and the shaft-shaped electrode 12 is 40mm. The voltage applied between the cylindrical electrode 11 and the shaft-shaped electrode 12 may be appropriately adjusted according to the dimensions of the cylindrical electrode 11 and the shaft-shaped electrode 12 so that spark discharge does not occur. In addition, if the applied voltage is 30000V or less, the generation amount of nitrogen oxides (NO X ) can be suppressed to a negligible level. The positions of the connection points between the cylindrical electrode 11 and the shaft-shaped electrode 12 and the electric circuit are not particularly limited, but in the figure, they are near the central portion in the axial direction of the cylindrical electrode 11 and the shaft-shaped electrode 12.

[0024] In order to process a large amount of gas to be processed in the plasma processing path 10, for example, the inner diameter of the cylindrical electrode 11 is 100mm, the outer diameter of the shaft-shaped electrode 12 is 20mm, and the axial length of the region where the cylindrical electrode 11 and the shaft-shaped electrode 12 face each other in the radial direction is 1600mm. This dimension is an example and is not limited thereto. The outer diameter of the shaft-shaped electrode 12 may be 10mm or more. If the inner diameter of the cylindrical electrode 11 is made too large, the distance between the cylindrical electrode 11 and the shaft-shaped electrode 12 becomes long, and it becomes difficult for discharge to occur. For this reason, it is preferable to satisfy 3≦(inner diameter of the cylindrical electrode 11 / outer diameter of the shaft-shaped electrode 12)≦6, (inner diameter of the cylindrical electrode 11 - outer diameter of the shaft-shaped electrode 12)≧20mm, and outer diameter of the shaft-shaped electrode 12≧10mm.

[0025] Also, if the cylindrical electrode 11 and the shaft-shaped electrode 12 are made too long in the axial direction, it becomes difficult to hold the cylindrical electrode 11 and the shaft-shaped electrode 12 concentrically with the insulating spacer 13 in the flow path 14. Therefore, the axial length of the flow path 14 is preferably 500mm or more and 2000mm or less.

[0026] The introduction path 15 of the plasma processing path 10 has a guide vane portion that changes the flow of the gas to be processed toward the flow path 14 into a spiral flow, and two or more obstacle portions that generate a trailing vortex in the aforementioned spiral flow on the intermediate flow path between the guide vane portion and the flow path 14.

[0027] When the gas to be processed fed into the introduction path 15 passes through the guide vane portion, it changes into a spiral flow (helical flow) that swirls in one direction toward the downstream side in the axial direction. Further, by hitting the obstacle portion, it changes into a spiral flow including a trailing vortex and then flows into the upstream inlet of the flow path 14, and passes through the flow path 14 in a state of a spiral flow that swirls in one direction toward the downstream side in the axial direction. Due to the spiralization and the generation of the trailing vortex of the gas to be processed, the gas to be processed flows through the flow path 14 along a long path, and the probability that the molecules of the gas to be processed are affected by the plasma is increased compared to the case where it flows straight in the axial direction.

[0028] Although it is not essential to adopt such spiralization or trailing vortex formation of the gas to be processed, it is preferably adopted to increase the generation probability of ionization and excitation of carbon dioxide (CO2 molecules) contained in the gas to be processed. The axial length of the flow path 14 is preferably 1000 mm or more in order to increase the moving distance of the spiral flow of the gas to be processed.

[0029] The connection path 21 introduces the gas to be processed flowing out from the downstream side of the flow path 14 of the plasma processing path 10 to the upstream side of the adsorption pipe line 22. The adsorption pipe line 22 has a layer of coal ash (clinker or clinker ash) 24 disposed inside a straight pipe body, and air-permeable barriers 22a disposed on the upstream side and the downstream side of the coal ash layer 24, respectively. The exhaust path 23 causes the gas to be processed flowing out from the downstream side of the adsorption pipe line 22 to flow out of the adsorption processing path 20.

[0030] The coal ash layer 24 is a layer in which a large number of coal ashes 24a are randomly packed inside the adsorption pipeline 22, and gaps 24b through which the gas to be treated passes are randomly formed between the layered coal ashes 24a. The coal ash layer 24 is held in a state of being formed by the upstream air permeability barrier 22a and the downstream air permeability barrier 22a. The air permeability barrier 22a is a member that regulates the movement of the coal ash 24a while allowing the gas to be treated to pass through, and is, for example, a net-like member that does not allow the coal ash 24a to pass through.

[0031] For the pipe material for forming the adsorption treatment path 20, it is preferable to adopt a resin pipe such as a vinyl chloride pipe in terms of poor reactivity with the gas to be treated and excellent insulation properties.

[0032] A blower fan (not shown) for sending the gas to be treated into the introduction path 15 of the plasma treatment path 10 and discharging it from the exhaust path 23 of the adsorption treatment path 20 may be arranged on the upstream side or the downstream side with respect to this carbon dioxide removal device 100.

[0033] Since the flow rate of the gas to be treated in the flow path 14 affects the performance of plasmaizing the gas to be treated, and the flow rate of the gas to be treated in the coal ash layer 24 affects the adsorption performance by the coal ash 24a, it may be set in consideration of the ionization degree required for the gas to be treated and the carbon dioxide removal rate required for the gas to be treated, and controlled by the output of the blower.

[0034] The gas to be treated that has exited the adsorption treatment path 20 is introduced into the buffer tank 30 through the passage 31, adjusted to a predetermined pressure in the buffer tank 30, and then sent into the next-stage plasma treatment path 10. As a result, the gas to be treated is stably sent to the plasma treatment path 10, the adsorption treatment path 20, and the buffer tank 30 without being affected by the capacity of the blower fan.

[0035] In a field where the powder of the coal ash 24 may enter the buffer tank 30, it is advisable to provide an on-off valve 32 at the bottom of the buffer tank 30 to discharge the powder of the coal ash 24 outside the system. Note that this on-off valve 32 is not necessarily required.

[0036] Moreover, according to the experiments of the present inventor, zeolite, imogolite, granite, and quartzite also showed the same carbon dioxide adsorption and separation effect as coal ash.

Explanation of Signs

[0037] 100 Carbon dioxide removal device 10 Plasma treatment path 11 Cylindrical electrode 12 Axial electrode 20 Adsorption treatment path 30 Buffer tank

Claims

1. A carbon dioxide adsorption and separation device comprising: a plasma treatment path into which a gas to be treated containing carbon dioxide is introduced and circulated, and plasma is applied to the gas to be treated; an adsorption treatment path filled with a coal ash layer, into which the gas to be treated having plasma applied thereto is introduced and circulated, and carbon dioxide contained in the gas to be treated is adsorbed by the coal ash layer and separated from the gas to be treated; and a buffer tank into which the gas to be treated exiting the adsorption treatment path is introduced and sent to the next-stage plasma treatment path at a predetermined pressure.

2. A carbon dioxide adsorption and separation device comprising: a plasma treatment path into which a gas to be treated containing carbon dioxide is introduced and circulated, and plasma is applied to the gas to be treated; an adsorption treatment path filled with a mineral powder layer selected from the group consisting of zeolite, imogolite, and granite, into which the gas to be treated having plasma applied thereto is introduced and circulated, and carbon dioxide contained in the gas to be treated is adsorbed by the mineral ash layer and separated from the gas to be treated; and a buffer tank into which the gas to be treated exiting the adsorption treatment path is introduced and sent to the next-stage plasma treatment path at a predetermined pressure.

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