Carbon dioxide recovery method and carbon dioxide recovery system

Abstract

Provided are a carbon dioxide recovery method and a carbon dioxide recovery system with which it is possible to suppress changes over time in the desorption rate of carbon dioxide. A carbon dioxide recovery method according to the present invention uses a plurality of recoverers (10) containing a carbon dioxide adsorbent (13), and recovers carbon dioxide by repeating an adsorption step (S1) for adsorbing carbon dioxide into each of the recoverers (10) and a desorption step (S3) for sequentially desorbing carbon dioxide from each of the recoverers (10). In the desorption step S3, the adsorbent (13) is housed in a plurality of gas chambers (121, 122) partitioned in the collector (10), and in the desorption step S3, a time difference is set, and carbon dioxide is sequentially desorbed from the adsorbent (13) in each of the gas chambers (121, 122).

Description

Technical Field

[0001] This invention relates to a method and system for carbon dioxide recovery. Background Technology

[0002] Methods for separating and recovering carbon dioxide from a mixed gas using adsorbent materials are known. Patent Document 1 discloses a method in which multiple recoverers equipped with adsorbent materials are used to sequentially perform adsorption, preheating, desorption, and cooling processes to recover carbon dioxide. The desorbed carbon dioxide can be reacted with hydrogen to produce methane. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-163247

[0004] For example, when the desorbed carbon dioxide is used to generate methane, hydrogen needs to be supplied in precise amounts for the reaction. Therefore, it is preferable that the amount of carbon dioxide desorbed does not change over time. However, in practice, the desorption rate of carbon dioxide is proportional to the amount of carbon dioxide adsorbed, and therefore changes as desorption proceeds. Specifically, when carbon dioxide is desorbed sequentially from multiple collectors, the desorption rate is highest at the very beginning of the desorption process for each collector, gradually decreases over time, and then increases sharply again when switching collectors as the desorption source. That is, the above method suffers from significant fluctuations in the carbon dioxide desorption rate. Summary of the Invention The problem that the invention aims to solve

[0005] The present invention was made in view of the above circumstances, and provides a carbon dioxide recovery method and carbon dioxide recovery system capable of suppressing the time-dependent changes in the desorption rate of carbon dioxide. Methods for solving problems

[0006] The carbon dioxide recovery method of the present invention uses multiple recovery devices containing adsorbent material for carbon dioxide. Carbon dioxide is recovered by repeatedly performing an adsorption step in which carbon dioxide is adsorbed into each of the recovery devices and a desorption step in which carbon dioxide is desorbed from each of the recovery devices in sequence. The adsorbent material is housed in multiple gas chambers formed separately within the recovery device. In the desorption step, a time difference is set so that carbon dioxide is desorbed from the adsorbent material in each of the gas chambers in sequence. Invention Effects

[0007] According to the present invention, a carbon dioxide recovery method and a carbon dioxide recovery system are provided that can suppress the time-dependent changes in the desorption rate of carbon dioxide. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating the structure of the recycler involved in this embodiment. Figure 2 yes Figure 1 A cross-sectional view of the reclaimer at section line II-II. Figure 3 This is a flowchart of the processes performed on the recycler. Figure 4 This is a diagram showing the timing of each process performed by multiple recyclers. Figure 5 This is a graph showing the change in the concentration of carbon dioxide contained in the recovered gas in the carbon dioxide recovery method according to this embodiment. Figure 6 This is a diagram showing the timing of each process performed by multiple recyclers in a modified example. Detailed Implementation

[0009] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. In addition, the following description and drawings may be appropriately simplified for the purpose of making the explanation clearer. It should be noted that, of course, Figure 1 The right-handed xyz coordinate system shown in the other figures is for ease of illustrating the positional relationships of the constituent elements. Generally, the positive z-axis is vertically upward, and the xy plane is horizontal; this is consistent across all the figures. Furthermore, the various configuration examples described below can be implemented individually or in appropriate combinations. These various configuration examples possess novel features that differ from one another. Therefore, these various configuration examples help to solve different purposes or issues and help to achieve different effects.

[0010] In this embodiment, a method for recovering carbon dioxide using four recoverers is described. First, using... Figure 1 as well as Figure 2 The structure of the recycler 10 involved in this embodiment will be explained. Figure 1 This is a schematic diagram showing the construction of the recycler 10. Figure 2 yes Figure 1 A cross-sectional view of the reclaimer 10 at section line II-II.

[0011] The recycler 10 is a cylindrical container. Figure 1 This is a cross-sectional view of the zx plane of the reclaimer 10. (Example) Figure 1 As shown, the recycler 10 includes a vent 11, a first air chamber 12_1, a second air chamber 12_2, an adsorbent material 13, valve pairs 14_1 and 14_2, and an oil chamber 15.

[0012] Vent 11 is a hole provided on the top and bottom of the recycler 10. Vent 11 can be connected to an external gas inlet device or suction device, for example, to introduce gas from the outside or release gas to the outside.

[0013] The first gas chamber 12_1 and the second gas chamber 12_2 are formed as chambers through which gas can pass in the vertical direction. For example... Figure 1 as well as Figure 2 As shown, both the first air chamber 12_1 and the second air chamber 12_2 have a shape in which two small chambers are spatially connected in a plurality of cylindrical passages, and an adsorbent material 13 is contained inside the passages. In addition, the first air chamber 12_1 and the second air chamber 12_2 are formed in a manner that separates them from each other.

[0014] The adsorbent 13 is a carbon dioxide adsorbent. The adsorbent 13 is not particularly limited to any substance capable of adsorbing carbon dioxide; for example, zeolite, activated carbon, silica gel, etc., can be used. These substances adsorb carbon dioxide at low temperatures and release carbon dioxide at high temperatures.

[0015] A valve pair 14_1 is connected to the upper and lower ends of the first air chamber 12_1, and a valve pair 14_2 is connected to the upper and lower ends of the second air chamber 12_2. By opening and closing the valve pairs 14_1 and 14_2, the air chamber 12_1 and the second air chamber 12_2 can be opened or closed, respectively.

[0016] like Figure 1 as well as Figure 2 As shown, the oil chamber 15 is a cavity configured to surround the portions of the first air chamber 12_1 and the second air chamber 12_2 containing the adsorbent material 13. The lower and upper ends of the oil chamber 15 are connected to external oil pipes, and the oil chamber 15 is filled with oil by supplying oil from the lower part to the upper part.

[0017] Figure 3 This is a flowchart of the processing performed by the recycler 10. Figure 3 In the example, steps S1 to S4 are repeatedly performed on the recycler 10. These processes can be executed, for example, by a control unit (not shown). The control unit can be, for example, a computer comprising ROM, RAM, and a CPU.

[0018] Step S1 is the step of adsorbing carbon dioxide into the recovery unit 10 (adsorption step). In step S1, while supplying cryogenic oil to the oil chamber 15, valve pair 14_1 and valve pair 14_2 are opened, and gas containing carbon dioxide is introduced through the lower vent 11. The introduced gas is discharged through either the first gas chamber 12_1 or the second gas chamber 12_2 through the upper vent 11. At this time, carbon dioxide is adsorbed onto the adsorbent material 13 contained in the first gas chamber 12_1 or the second gas chamber 12_2.

[0019] Step S2 is the heating step of the heat recovery unit 10. In step S2, valve pair 14_1 and valve pair 14_2 are closed, and high-temperature oil is supplied to the oil chamber 15. By heating the heat recovery unit 10 in this step, carbon dioxide can be easily desorbed from the adsorbent material 13 in the next step.

[0020] Step S3 is the step of desorbing carbon dioxide from the recoverer 10 (desorption step). In step S3, a time difference is set, and step S3_1, which desorbs carbon dioxide from the adsorbent material 13 in the first gas chamber 12_1, and step S3_2, which desorbs carbon dioxide from the adsorbent material 13 in the second gas chamber 12_2, are performed sequentially.

[0021] First, in step S3_1, while high-temperature oil is being supplied to oil chamber 15, valve 14_1 is opened, and a vacuum pump is connected to the lower vent 11 to reduce the pressure inside the recovery unit 10. Additionally, a gas such as hydrogen is introduced through the upper vent 11. As a result, carbon dioxide is desorbed from the adsorbent material 13 in the first gas chamber 12_1. The desorbed carbon dioxide is then recovered by the vacuum pump connected to the lower vent 11.

[0022] After a preset time has elapsed since step S3_1, step S3_2 begins. In step S3_2, high-temperature oil is supplied to oil chamber 15, and valve 14_2 is opened while the pressure in the recoverer 10 is reduced. As a result, carbon dioxide is desorbed from the adsorbent material 13 in the second gas chamber 12_2. The desorbed carbon dioxide is recovered by a vacuum pump connected to the vent 11 at the lower end.

[0023] Step S4 is the cooling step of the cooling recovery unit 10. In step S4, valve pair 14_1 and valve pair 14_2 are closed, and low-temperature oil is supplied to the oil chamber 15. By cooling the cooling recovery unit 10 in this step, carbon dioxide can be easily adsorbed onto the adsorbent material 13 in the next step.

[0024] In this embodiment, any one of the recyclers performs any one of steps S1 to S4, so that the four recyclers execute steps S1 to S4 in sequence. Figure 4 This is a graph showing the timing of each process performed by multiple recyclers. Figure 4 In the example, when the first collector begins the cooling step, the second collector begins the adsorption step, the third collector begins the heating step, and the fourth collector begins the desorption step (step S3_2) to desorb from the second gas chamber.

[0025] exist Figure 4In the example, steps S1, S2, S3_2, and S4 are all performed at 30-minute intervals, while steps S2, S3_1, and S3_2 are all performed at 15-minute intervals. During this process, the desorption of carbon dioxide from each chamber begins at 15-minute intervals. Figure 5 The graph shows the change in the concentration of carbon dioxide in the recovered gas after desorption of carbon dioxide under these conditions.

[0026] exist Figure 5 In the graph, the short dashed line represents the change in the concentration of carbon dioxide in the gas after desorption from each of the second chambers. The concentration rises sharply at the very beginning of desorption from the second chamber (0 minutes, 30 minutes, 60 minutes), then gradually decreases, and repeats in this manner. In addition, the long dashed line represents the curve showing the change in the concentration of carbon dioxide in the gas after desorption from each of the first chambers. This concentration rises sharply at the very beginning of desorption from the first chamber (15 minutes, 45 minutes, 75 minutes), then gradually decreases, and repeats in this manner.

[0027] Assuming that each recoverer has only one gas chamber, as is the case in the prior art, the concentration of carbon dioxide in the recovered gas exhibits the dynamics shown by the dashed line. On the other hand, in this embodiment, the concentration of carbon dioxide in the gas recovered from the entire recovery unit is the average of the values ​​represented by the two dashed lines, as shown by the solid line. Figure 5 In the example, the solid line represents a 52% smaller change in carbon dioxide concentration than the dashed line. This is because each recoverer has multiple chambers, and setting a time difference allows carbon dioxide to desorb from each chamber, thus dispersing the peak desorption rate.

[0028] It should be noted that the present invention is not limited to the above embodiments, and appropriate modifications can be made without departing from the spirit of the invention.

[0029] For example, in the above embodiment, each recoverer is configured with two gas chambers, but a configuration with three or more gas chambers is also possible. In this case, by setting a time difference to allow carbon dioxide to desorb sequentially from the adsorbent material in each gas chamber, the time-dependent variation in the carbon dioxide desorption rate can be suppressed. As an example, Figure 6 The diagram shows the timing of each process performed on multiple recoverers, each with n chambers. The more chambers each recoverer has, the better it can disperse the peak concentration of carbon dioxide, and therefore it is preferred.

[0030] Furthermore, while the above embodiment illustrates an example of performing heating and cooling steps, these steps can also be omitted. In this case, two or more recyclers are sufficient.

[0031] It should be noted that, preferably, the adsorbent materials contained in the gas chambers of each recoverer have approximately the same adsorption capacity for carbon dioxide. During the desorption step, carbon dioxide is sequentially desorbed from the adsorbent materials in each gas chamber at approximately equal time intervals. In this case, the peak concentration of carbon dioxide in the recovered gas can occur at substantially uniform time intervals and with substantially the same intensity. Therefore, the temporal variation in the carbon dioxide desorption rate can be suppressed. Explanation of reference numerals in the attached figures

[0032] 10 Recyclers 11 vents 12_1 First air chamber 12_2 Second air chamber 13 Adsorption Materials Valve pairs 14_1 and 14_2 15 oil chambers.

Claims

1. A carbon dioxide recovery method, using a plurality of carbon dioxide-occluding adsorbents, carbon dioxide is recovered by repeatedly performing an adsorption step of adsorbing carbon dioxide to each of the adsorbents and a desorption step of desorbing carbon dioxide from each of the adsorbents in turn, the adsorbents are occluded in a plurality of gas chambers formed in the recovery device, in the desorption step, a time difference is provided to desorb carbon dioxide from the adsorbents in each of the gas chambers in turn.

2. The carbon dioxide recovery method according to claim 1, wherein the adsorption capacity of carbon dioxide of the adsorbents occluded in each of the gas chambers is substantially the same, in the desorption step, a substantially same time interval is provided to desorb carbon dioxide from the adsorbents in each of the gas chambers in turn.

3. A carbon dioxide recovery system, comprising: a plurality of recovery devices that occlude carbon dioxide-occluding adsorbents in a plurality of gas chambers formed in separation; and a control unit that repeatedly performs an adsorption step of adsorbing carbon dioxide to each of the adsorbents and a desorption step of desorbing carbon dioxide from each of the adsorbents in turn, the control unit provides a time difference in the desorption step to desorb carbon dioxide from the adsorbents in each of the gas chambers in turn.

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