Carbon dioxide recovery system and carbon dioxide recovery method

Abstract

This invention provides a carbon dioxide recovery system for suppressing collisions in the absorbent. The carbon dioxide recovery system includes: an absorption tower that contacts a carbon dioxide-containing gas with an absorbent to remove carbon dioxide from the gas; and a regeneration tower that recovers carbon dioxide from the absorbent that has absorbed it. The absorption tower has: a plurality of nozzles arranged spirally on its inner wall relative to the central axis of the absorption tower; and a plurality of spray devices that spray the absorbent, the spray devices being installed at the nozzles. The multiple spray devices spray the absorbent towards the central axis of the absorption tower in a horizontal direction orthogonal to the central axis.

Description

Technical Field

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

[0002] Japanese Patent Application Publication No. 2012-030168 (Patent Document 1) discloses a gas-liquid contact device having multiple spray nozzles that spray CO2 absorbent liquid downwards inside a CO2 absorption tower through which exhaust gas rises and passes, and that bring the rising exhaust gas into contact with the CO2 absorbent liquid.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-030168 Summary of the Invention

[0004] Depending on the spray direction or area of ​​the absorbent liquid, the absorbent liquid may sometimes collide with each other, thus hindering the contact between the waste gas and the absorbent liquid. Furthermore, if the absorbent liquid that has absorbed carbon dioxide is bounced back on the inner wall of the absorption tower, it may come into contact with the waste gas again. Therefore, the carbon dioxide recovery efficiency may decrease, leaving room for improvement.

[0005] The purpose of this invention is to provide a carbon dioxide recovery system that suppresses collisions in the absorbent.

[0006] The technical structure and effects of this invention will be described below. The mechanism of action of this invention includes speculation. The correctness of the mechanism of action does not limit the scope of the claims.

[0007] [1] A carbon dioxide recovery system, comprising:

[0008] An absorption tower that contacts carbon dioxide-containing gas with an absorbent to remove carbon dioxide from the gas; and a regeneration tower that recovers carbon dioxide from the absorbent that has absorbed carbon dioxide.

[0009] The absorption tower has: a plurality of spray holes arranged spirally on its inner wall relative to the central axis of the absorption tower; and a plurality of spray devices for spraying the absorbent liquid.

[0010] The plurality of spray devices are installed in the plurality of spray nozzles.

[0011] The plurality of spray devices spray the absorbent liquid toward the central axis of the absorption tower in a horizontal direction orthogonal to the central axis.

[0012] According to this structure, multiple nozzles are arranged in a spiral pattern on the inner wall of the absorption tower, and the absorbent liquid is sprayed horizontally towards the central axis of the absorption tower, thus suppressing collisions between the absorbent liquids. Furthermore, the maximum spray distance of the absorbent liquid is the diameter of the absorption tower, ensuring the required gas-liquid contact time for carbon dioxide absorption for an extended period.

[0013] [2] According to the carbon dioxide recovery system described in [1], wherein,

[0014] The inner wall of the absorption tower has at least one of the following functions: hydrophobic or oleophobic.

[0015] According to this structure, the absorbent liquid that has absorbed carbon dioxide easily forms droplets or liquid films upon reaching the inner wall of the absorption tower and falls under its own weight, thus separating the off gas from the carbon dioxide-containing gas from the absorbent liquid. Furthermore, it can prevent the absorbent liquid that has absorbed carbon dioxide from bouncing back onto the inner wall of the absorption tower.

[0016] [3] According to the carbon dioxide recovery system described in [1], wherein,

[0017] The spacing between the plurality of nozzles in the helical direction varies.

[0018] By varying the density of the multiple nozzles arranged in a spiral pattern, the spray area or spray volume of the absorbent can be adjusted. For example, in areas where carbon dioxide is not easily absorbed, by reducing the spacing of the spiral-arranged nozzles, a larger amount of absorbent can be sprayed, thereby absorbing more carbon dioxide.

[0019] [4] The carbon dioxide recovery system according to any one of [1] to [3] includes the following steps:

[0020] The absorbent liquid sprayed from the plurality of spray devices absorbs carbon dioxide from the carbon dioxide-containing gas before reaching the inner wall of the absorption tower;

[0021] After reaching the inner wall of the absorption tower, the absorbent liquid becomes droplets or liquid film and falls by its own weight, thereby being stored in the lower part of the absorption tower.

[0022] The absorbent stored in the lower part of the absorption tower is sent to the regeneration tower; and

[0023] The waste gas from which carbon dioxide has been removed rises toward the top of the absorption tower.

[0024] According to this structure, in a carbon dioxide recovery system, the process of absorbing carbon dioxide with absorbent liquid and the process of recovering the absorbent liquid that has absorbed carbon dioxide can be carried out simultaneously in one absorption tower, which can help to miniaturize the carbon dioxide recovery system.

[0025] [5] A carbon dioxide recovery method using any one of [1] to [3], the carbon dioxide recovery method comprising the following steps:

[0026] The absorbent liquid sprayed from the plurality of spray devices absorbs carbon dioxide from the carbon dioxide-containing gas before reaching the inner wall of the absorption tower;

[0027] After reaching the inner wall of the absorption tower, the absorbent liquid becomes droplets or liquid film and falls by its own weight, thereby being stored in the lower part of the absorption tower.

[0028] The absorbent stored in the lower part of the absorption tower is sent to the regeneration tower; and

[0029] The waste gas from which carbon dioxide has been removed rises toward the top of the absorption tower. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the carbon dioxide recovery system according to the first embodiment.

[0031] Figure 2 This is an example of an absorption tower in the carbon dioxide recovery system according to the first embodiment.

[0032] Figure 3 yes Figure 2 The diagram shows a cross-sectional view of the absorption tower in the horizontal direction.

[0033] Figure 4 This is an example of an absorption tower in the carbon dioxide recovery system according to the second embodiment. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described. However, this embodiment does not limit the technical scope of the present invention.

[0035] (First Embodiment)

[0036] Figure 1 This is a schematic diagram illustrating the carbon dioxide recovery system according to the first embodiment. Figure 1The carbon dioxide recovery system 1 includes: a carbon dioxide gas supply unit 10; an absorption tower 20 that contacts the carbon dioxide gas with an absorbent liquid to remove carbon dioxide from the carbon dioxide gas; and a regeneration tower 30 that recovers carbon dioxide from the absorbent liquid that has absorbed carbon dioxide.

[0037] The carbon dioxide gas supply unit 10 is a source of supply for carbon dioxide-containing gas and discharges carbon dioxide-containing gas. The carbon dioxide gas supply unit 10 is, for example, a combustion device installed in a power plant, factory, etc. In this case, the carbon dioxide-containing gas is combustion exhaust gas produced during combustion. In addition to carbon dioxide, the carbon dioxide-containing gas may also contain oxygen, nitrogen, water vapor, nitrogen oxides, or sulfur oxides.

[0038] A carbon dioxide gas supply unit 10 is connected to the absorption tower 20, for example, via an exhaust gas pipeline, and supplies carbon dioxide-containing gas into the absorption tower 20. Preferably, the location of the carbon dioxide gas supply unit 10 within the absorption tower 20 is below the locations of the plurality of nozzles 21. The carbon dioxide-containing gas supplied from the carbon dioxide gas supply unit 10 rises towards the upper part of the absorption tower 20. The carbon dioxide-containing gas can rise while rotating along the inner wall of the absorption tower 20.

[0039] Figure 2 This is an example of an absorption tower in the carbon dioxide recovery system according to the first embodiment. The absorption tower 20 can be cylindrical. In the absorption tower 20, carbon dioxide-containing gas is brought into contact with an absorbent liquid to remove carbon dioxide from the carbon dioxide-containing gas.

[0040] The absorbent is a liquid that absorbs carbon dioxide, such as a solvent and a compound that absorbs carbon dioxide. The solvent can be water, an organic solvent, or a mixture thereof. Examples of organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, N,N-dimethylformamide, dimethyl sulfoxide, or a mixture thereof.

[0041] The compounds used to absorb carbon dioxide are not particularly limited. Compounds that absorb carbon dioxide may include, for example, amine compounds. Examples of amine compounds include monoethanolamine, diethanolamine, diethylethanolamine, triethanolamine, tetraethylenepentamine, methyldiethanolamine, dibutylamine, 2-amino-2-methyl-1-propanol, m-xylenediamine, polyethyleneimine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and piperazine. One compound may be used alone, or two or more may be used simultaneously. In addition to amine compounds, the absorbent may contain any additives.

[0042] The absorption tower 20 has a plurality of nozzles 21 arranged spirally on its inner wall relative to the central axis of the absorption tower 20, and a plurality of spraying devices for spraying the absorbent liquid. The plurality of spraying devices are installed at the plurality of nozzles 21. Additionally, in Figure 2 In the middle, multiple spray devices are installed at multiple nozzles 21 (not shown).

[0043] like Figure 2 As shown, multiple nozzles 21 and multiple spray devices (not shown) are arranged in a spiral pattern relative to the central axis of the absorption tower 20 on the inner wall of the absorption tower 20. That is, no other nozzles or spray devices are arranged on the inner wall surface at the same height as the pair of nozzles and spray devices arranged therein in the absorption tower 20. Furthermore, in Figure 2 The image shows only a portion of the plurality of nozzles 21 arranged in a spiral shape; the number of nozzles 21 is not limited to this.

[0044] The multiple nozzles 21 can be configured to penetrate the wall of the absorption tower 20, or they can be configured only on the inner wall side of the absorption tower 20. The size of each of the multiple nozzles 21 can be appropriately adjusted according to the size or shape of the spray device installed on the nozzles 21.

[0045] The spacing of the multiple nozzles 21 in the helical direction varies depending on the size of the nozzles 21, the flow rate of the sprayed absorbent, or the spray area, and is configured such that the sprayed absorbent does not interfere with each other. The spacing of the multiple nozzles 21 can be, for example, equal.

[0046] Multiple spraying devices are devices for spraying absorbent liquid. These multiple spraying devices are, for example, devices for atomizing the absorbent liquid, such as spray nozzles. Multiple spraying devices are installed in multiple spray holes 21. The multiple spraying devices can be installed in the multiple spray holes 21 together with piping for supplying absorbent liquid into the spraying devices.

[0047] Figure 3 yes Figure 2 The diagram shows a cross-sectional view of the absorption tower in the horizontal direction. Figure 3 Multiple nozzles 21 are shown disposed on the inner wall surface of the absorption tower 20. Figure 3 In the diagram, the arrows, represented by dashed lines, indicate the trajectories traced by the absorbent liquid sprayed from a spray device (not shown) installed at multiple nozzles 21. Additionally, in... Figure 3 Only a portion of the plurality of nozzles 21 arranged in a spiral shape is shown in the image. Furthermore, in... Figure 3 For convenience, multiple nozzles 21 are shown on the same cross section. However, as mentioned above, the positions of the multiple nozzles 21 are different in the height direction of the absorption tower 20, so the nozzles 21 are not arranged on the same cross section.

[0048] Multiple spray devices spray absorbent liquid towards the central axis of the absorption tower 20, in a horizontal direction orthogonal to the central axis of the absorption tower 20. This helps to suppress collisions between the absorbent liquids sprayed from the spray devices.

[0049] The absorbent sprayed from multiple spray devices preferably reaches the inner wall surface of the absorption tower 20. In this case, such as Figure 3 As shown, the maximum spray distance of the absorbent liquid is the diameter of the absorption tower 20, which can ensure the gas-liquid contact time required for carbon dioxide absorption for a long time.

[0050] The absorbent liquid sprayed from multiple spray devices comes into gas-liquid contact with the rising carbon dioxide-containing gas inside the absorption tower 20 before reaching the inner wall surface opposite each spray device, thus absorbing the carbon dioxide from the gas. For example... Figure 2 As shown, the absorbent liquid (hereinafter also referred to as rich liquid 22) that has absorbed carbon dioxide from the carbon dioxide-containing gas becomes droplets or a liquid film when it reaches the inner wall of the absorption tower 20. It falls down along the inner wall of the absorption tower 20 by its own weight and is stored in the lower part of the absorption tower 20. The rich liquid 22 stored in the lower part of the absorption tower 20 is supplied to the regeneration tower 30.

[0051] On the other hand, carbon dioxide-containing gas removes carbon dioxide through contact with the absorbent liquid, thus becoming waste gas. In this specification, waste gas refers to gas with a reduced carbon dioxide concentration compared to carbon dioxide-containing gas. Therefore, waste gas can be gas from which carbon dioxide has been completely removed, or gas from which carbon dioxide has not been completely removed. The waste gas rises towards the upper part of the absorption tower 20 and is discharged to the outside of the absorption tower 20. For example, the waste gas can be discharged into the atmosphere or sent to a cleaning device for further cleaning of waste gas. Furthermore, a waste gas cleaning device can be installed inside the absorption tower 20.

[0052] Thus, within the absorption tower 20, gas-liquid separation is performed between the waste gas from which carbon dioxide has been removed and the absorbent liquid (rich liquid 22) that has absorbed carbon dioxide. In conventional carbon dioxide recovery systems, there are sometimes cases where a separate process for recovering the rich liquid 22 is required. However, in the carbon dioxide recovery system 1 according to the first embodiment, the processes of absorbing carbon dioxide with the absorbent liquid and recovering the rich liquid 22 can be performed within a single absorption tower 20, which also helps to miniaturize the carbon dioxide recovery system.

[0053] The inner wall surface of the absorption tower 20 preferably has at least one of the functions of hydrophobicity or oleophobicity. By having these functions, the absorbent liquid adhering to the inner wall surface easily forms droplets or liquid films that fall due to their own weight, facilitating the aforementioned gas-liquid separation of the waste gas and the absorbent liquid. The hydrophobic or oleophobic function can be imparted, for example, through coating or by the material of the inner wall surface.

[0054] In regeneration tower 30, carbon dioxide is recovered from the rich liquid 22 supplied by absorber tower 20. In regeneration tower 30, for example, the rich liquid 22 is regenerated. The regeneration process is not particularly limited; for example, carbon dioxide can be recovered from the rich liquid 22 by heating it. The absorbent regenerated by removing carbon dioxide from the rich liquid 22 (hereinafter also referred to as lean liquid) can be reused by supplying it to a spray device of absorber tower 20. In this case, the lean liquid can be supplied directly to multiple spray devices of absorber tower 20, or it can be purified before being supplied to a spray device of absorber tower 20.

[0055] (Second Implementation)

[0056] Next, the carbon dioxide recovery system according to the second embodiment will be described. The carbon dioxide recovery system according to the second embodiment differs from the carbon dioxide recovery system according to the first embodiment in that the arrangement positions of the plurality of nozzles 21 in the absorption tower 20 are different. Furthermore, in the second embodiment, the parts that are the same as those in the first embodiment are subject to the above description.

[0057] Figure 4 This is an example of the absorption tower in the carbon dioxide recovery system 1 according to the second embodiment. Figure 4 In the absorption tower 20 shown, the spacing of the multiple nozzles 21 in the helical direction varies. Furthermore, in Figure 4 The image shows only a portion of the plurality of nozzles 21 arranged in a spiral shape; the number of nozzles 21 is not limited to this.

[0058] like Figure 4 As shown, "the spacing of the nozzles in the spiral direction varies in density" means that the nozzles have either a narrow spacing region or a wide spacing region. By varying the spacing of the multiple nozzles 21, the spray area or spray volume of the absorbent can be adjusted. For example, in areas where carbon dioxide is not easily absorbed, by reducing the spacing of the spirally arranged nozzles, a larger amount of absorbent can be sprayed, thereby absorbing more carbon dioxide.

[0059] As described above, a carbon dioxide recovery system that suppresses absorption liquid collision is provided. Furthermore, by using the carbon dioxide recovery system according to this embodiment, a carbon dioxide recovery method for recovering carbon dioxide from a carbon dioxide-containing gas is provided.

[0060] It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is not shown in the foregoing description, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0061] Symbol Explanation

[0062] 1-Carbon dioxide recovery system, 10-Carbon dioxide gas supply unit, 20-Absorption tower, 21-Spray nozzle, 22-Rich liquid, 30-Regeneration tower.

Claims

1. A carbon dioxide recovery system, characterized in that, have: An absorption tower that contacts carbon dioxide-containing gas with an absorbent to remove carbon dioxide from the gas; and a regeneration tower that recovers carbon dioxide from the absorbent that has absorbed carbon dioxide. The absorption tower has: a plurality of spray holes arranged spirally on its inner wall relative to the central axis of the absorption tower; and a plurality of spray devices for spraying the absorbent liquid. The plurality of spray devices are installed in the plurality of spray nozzles. The plurality of spray devices spray the absorbent liquid toward the central axis of the absorption tower in a horizontal direction orthogonal to the central axis.

2. The carbon dioxide recovery system according to claim 1, characterized in that, The inner wall of the absorption tower has at least one of the following functions: hydrophobic or oleophobic.

3. The carbon dioxide recovery system according to claim 1, characterized in that, The spacing between the plurality of nozzles in the helical direction varies.

4. The carbon dioxide recovery system according to any one of claims 1 to 3, characterized in that, Includes the following steps: The absorbent liquid sprayed from the plurality of spray devices absorbs carbon dioxide from the carbon dioxide-containing gas before reaching the inner wall of the absorption tower; After reaching the inner wall of the absorption tower, the absorbent liquid becomes droplets or liquid film and falls by its own weight, thereby being stored in the lower part of the absorption tower. The absorbent stored in the lower part of the absorption tower is sent to the regeneration tower; and The waste gas from which carbon dioxide has been removed rises toward the top of the absorption tower.

5. A carbon dioxide recovery method using the carbon dioxide recovery system according to any one of claims 1 to 3, characterized in that the carbon dioxide recovery method comprises the following steps: The absorbent liquid sprayed from the plurality of spray devices absorbs carbon dioxide from the carbon dioxide-containing gas before reaching the inner wall of the absorption tower; After reaching the inner wall of the absorption tower, the absorbent liquid becomes droplets or liquid film and falls by its own weight, thereby being stored in the lower part of the absorption tower. The absorbent stored in the lower part of the absorption tower is sent to the regeneration tower; and The waste gas from which carbon dioxide has been removed rises toward the top of the absorption tower.

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