Acidic-gas adsorption device

Abstract

An acidic-gas adsorption device is provided with which the efficiency of acidic-gas adsorption can be improved. The acidic-gas adsorption device according to an embodiment of the present invention comprises: an acidic-gas adsorption part through which a fluid can pass in a given direction; and one case. The acidic-gas adsorption part includes acidic-gas adsorbents capable of adsorbing acidic gases. The acidic-gas adsorption part comprises a first adsorption part and a second adsorption part disposed downstream from the first adsorption part along the fluid-passing direction. The first adsorption part includes a first acidic-gas adsorbent, which is relatively low in the ability to adsorb acidic gases but is high in acidic-gas adsorption capacity. The second adsorption part includes a second acidic-gas adsorbent, which is relatively high in the ability to adsorb acidic gases but is low in acidic-gas adsorption capacity. The one case accommodates both the first adsorption part and the second adsorption part.

Description

Acid Gas Adsorption Equipment

[0001] The present invention relates to an acid gas adsorption device.

[0002] In recent years, efforts have been made to separate and recover acidic gases contained in the atmosphere in order to reduce the environmental impact. Such acidic gases include carbon dioxide (CO ), which is a cause of global warming. ２ A typical example of such an approach is the carbon dioxide capture, utilization and storage (CCUS) cycle. As a carbon dioxide adsorption device used for separating and capturing carbon dioxide, a gas separation unit equipped with a carbon dioxide adsorption section having a pellet structure has been proposed (see, for example, Patent Document 1). In such a carbon dioxide adsorption device, a carbon dioxide adsorbent is used to separate and capture CO ２ At a desorption temperature exceeding the adsorption temperature, ２ In such a carbon dioxide adsorption device, CO ２ Therefore, it is desirable to improve the adsorption efficiency of

[0003] International Publication No. 2014 / 170184

[0004] A primary object of the present invention is to provide an acid gas adsorption device capable of improving the efficiency of adsorption of acid gases.

[0005] [1] An acidic gas adsorption device according to an embodiment of the present invention includes an acidic gas adsorption unit through which a fluid can pass in a predetermined direction. The acidic gas adsorption unit includes an acidic gas adsorbent capable of adsorbing acidic gas. The acidic gas adsorption unit includes a first adsorption unit and a second adsorption unit disposed downstream of the first adsorption unit in the fluid passage direction. The first adsorption unit includes a first acidic gas adsorbent having a relatively low adsorption power for adsorbing acidic gases and a large adsorption capacity for acidic gases. The second adsorption unit includes a second acidic gas adsorbent having a relatively high adsorption power for adsorbing acidic gases and a small adsorption capacity for acidic gases. [2] In the acidic gas adsorption device described in [1] above, the acidic gas may be carbon dioxide. [3] In the acidic gas adsorption device described in [1] or [2] above, the equilibrium acidic gas concentration of the first acidic gas adsorbent may exceed 100 ppm, and the equilibrium acidic gas concentration of the second acidic gas adsorbent may be 100 ppm or less. [4] In the acidic gas adsorption device described in [3] above, the first acidic gas adsorbent may contain a tertiary amino group, and the second acidic gas adsorbent may contain a primary amino group and / or a secondary amino group. [5] In the acidic gas adsorption device described in any of [1] to [4] above, the first adsorption section may be divided into multiple sections in a direction perpendicular to the fluid passage direction. [6] In the acidic gas adsorption device described in any of [1] to [4] above, the second adsorption section may be divided into multiple sections in a direction perpendicular to the fluid passage direction. [7] The acidic gas adsorption device described in any of [1] to [6] above may further include a single case. The single case may accommodate the first adsorption section and the second adsorption section together.

[0006] According to the embodiment of the present invention, it is possible to realize an acidic gas adsorption device that can improve the efficiency of adsorption of acidic gases.

[0007] FIG. 1 is a schematic configuration diagram of an acid gas adsorption apparatus according to one embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an acid gas adsorption apparatus according to another embodiment of the present invention. FIG. 3 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention. FIG. 4 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention. FIG. 5 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention. FIG. 6 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention. FIG. 7 is a schematic configuration diagram of an acid gas adsorption apparatus according to yet another embodiment of the present invention. FIG. 8 is a schematic configuration diagram of one embodiment of the first block of FIG. 6. FIG. 9 is a schematic perspective view of another embodiment of the first block of FIG. 6. FIG. 10 is a central cross-sectional view of the first block of FIG. 9.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Overview of the Acidic Gas Adsorption Apparatus FIG. 1 is a schematic diagram of an acidic gas adsorption apparatus according to one embodiment of the present invention. The illustrated acidic gas adsorption apparatus 100 includes an acidic gas adsorption unit 1 through which a fluid can pass in a predetermined direction. The acidic gas adsorption unit 1 includes an acidic gas adsorbent capable of adsorbing acidic gases. The acidic gas adsorption unit 1 includes a first adsorption unit 11 and a second adsorption unit 12 disposed downstream of the first adsorption unit 11 in the direction of fluid passage. The first adsorption unit 11 includes a first acidic gas adsorbent having a relatively low adsorption power for adsorbing acidic gases and a large adsorption capacity for acidic gases. The second adsorption unit 12 includes a second acidic gas adsorbent having a relatively high adsorption power for adsorbing acidic gases and a small adsorption capacity for acidic gases. In other words, the adsorption power of the first acidic gas adsorbent is smaller than that of the second acidic gas adsorbent, and the adsorption capacity of the first acidic gas adsorbent is larger than that of the second acidic gas adsorbent. In an acidic gas adsorption device, a fluid containing acidic gas is supplied to the acidic gas adsorption section, and the acidic gas adsorbent adsorbs the acidic gas. Therefore, the acidic gas concentration in the fluid decreases toward the downstream side in the fluid flow direction. When the acidic gas adsorption section contains the same acidic gas adsorbent throughout its entirety, the acidic gas concentration is relatively high in the upstream portion of the acidic gas adsorption section, so the acidic gas adsorbent can adsorb the acidic gas. However, the acidic gas concentration is relatively low in the downstream portion of the acidic gas adsorption section, so the acidic gas adsorbent may not be able to adequately adsorb the acidic gas. In contrast, according to one embodiment of the present invention, the first adsorption section located upstream in the fluid flow direction contains a first acidic gas adsorbent with a larger acidic gas adsorption capacity than the second acidic gas adsorbent. Therefore, the first acidic gas adsorbent can adequately adsorb acidic gas from a fluid with a relatively high acidic gas concentration. Furthermore, the second adsorption section, which is located downstream in the direction in which the fluid passes, contains a second acidic gas adsorbent that has a greater adsorption power for adsorbing acidic gases than the first acidic gas adsorbent. Therefore, even if the concentration of acidic gases in the fluid that has passed through the first adsorption section is relatively low, the second acidic gas adsorbent can stably adsorb acidic gases from the fluid.Therefore, compared to a case where the acidic gas adsorption section contains the same acidic gas adsorbent throughout its entirety, the adsorption performance of the entire acidic gas adsorption device can be improved.

[0010] The acid gas to be adsorbed by the acid gas adsorption device is, for example, carbon dioxide (CO ２ ), hydrogen sulfide, sulfur dioxide, nitrogen dioxide, dimethyl sulfide (DMS), hydrogen chloride, etc. In one embodiment, the acid gas is carbon dioxide (CO ２ ), and the fluid is CO ２ It is a contained gas. ２ The contained gas is CO ２ In addition to the above, nitrogen may be contained. ２ The contained gas is typically air (atmospheric air). ２ CO in the containing gas ２ The concentration is, for example, 100 ppm (volume basis) or more and 2% by volume or less. In the following, the acid gas is carbon dioxide (CO ２ ) will be described in detail below.

[0011] CO of the first acid gas adsorbent ２ Adsorption capacity (hereinafter referred to as CO ２ The adsorption capacity of the second acid gas adsorbent is ２ The CO adsorption capacity of the first acid gas adsorbent is larger than that of the first acid gas adsorbent. ２ The adsorption force to adsorb CO ２ The adsorption capacity of the second acid gas adsorbent is ２ is smaller than the adsorption force.

[0012] Acid gas adsorbent CO ２ Adsorption capacity was measured at 25°C, 50% RH, CO ２ Under a partial pressure of 15 kPa, the amount of CO adsorbable per 1 kg of acidic gas adsorbent (when the acidic gas adsorbent is supported on a porous carrier, the total weight of the acidic gas adsorbent and the porous carrier is 1 kg) is ２ The amount of CO in the first acidic gas adsorbent is 100%. ２ The adsorption capacity is, for example, 1.5 mol / kg-adsorbent or more, preferably 2.0 mol / kg-adsorbent or more, and more preferably 2.5 mol / kg-adsorbent or more.２ The adsorption capacity can be measured, for example, by the method described in Document 3-2-1 of the 2nd FY2015 Carbon Dioxide Capture and Storage Evaluation Committee (2) (hereinafter the same).

[0013] CO of the first acid gas adsorbent ２ The adsorption capacity is determined by the equilibrium acid gas concentration (equilibrium CO ２ The CO concentration of the acid gas adsorbent can be evaluated. ２ The adsorption capacity is determined by the equilibrium acid gas concentration (equilibrium CO ２ The higher the concentration of acidic gases (the higher the CO ２ The lower the equilibrium acid gas concentration (equilibrium CO ２ The equilibrium acid gas concentration can be measured, for example, by placing an acid gas adsorbent having an adsorption capacity in large excess of the acid gas contained in a desiccator filled with air at 25°C and 50% RH, and quantitatively analyzing the acid gas concentration in the desiccator after 4 hours using an infrared spectrometer (the same applies below). ２ Even if the adsorption force is below the upper limit, CO ２ When the concentration is relatively high (CO ２ When the concentration exceeds the lower limit of the equilibrium acid gas concentration of the first acid gas adsorbent (typically 100 ppm), the first acid gas adsorbent has a relatively large capacity (the CO ２ (above the lower limit of adsorption capacity) ２ In addition, the CO ２ As the adsorption power increases, CO ２ Therefore, the energy required to desorb CO from the first acidic gas adsorbent becomes large. ２ When the adsorptive force is equal to or less than the upper limit, energy saving in the desorption step described below can be achieved.

[0014] Equilibrium acid gas concentration of the second acid gas adsorbent (equilibrium CO ２The CO concentration of the second acidic gas adsorbent is, for example, 100 ppm or less, preferably 75 ppm or less, more preferably 50 ppm or less, and is, for example, 10 ppm or more. ２ The adsorption capacity is, for example, less than 2.0 mol / kg-adsorbent, preferably less than 1.5 mol / kg-adsorbent, more preferably 1.0 mol / kg-adsorbent or less, for example, 0.5 mol / kg-adsorbent or more. ２ If the adsorption force is above the lower limit, CO ２ When the concentration is relatively low (CO ２ Even if the concentration is equal to or lower than the lower limit (typically 100 ppm) of the equilibrium acid gas concentration of the first acid gas adsorbent, ２ The second acid gas adsorbent can stably adsorb CO ２ Even if the adsorption capacity is below the upper limit, the first acidic gas adsorbent may have a relatively large amount of CO ２ Therefore, the efficiency of the acid gas adsorption device as a whole does not decrease.

[0015] CO ２ The first acidic gas adsorbent capable of adsorbing the above-mentioned acidic gas typically contains at least a tertiary amino group. The first acidic gas adsorbent may contain only tertiary amino groups as the amino group, or may contain primary amino groups and / or secondary amino groups in addition to the tertiary amino group. Examples of first acidic gas adsorbents having a tertiary amino group include nitrogen-containing compounds having a tertiary amino group. Specific examples include tertiary amines such as methyldiethylamine and triethanolamine; substituted piperazine compounds such as 1-(2-hydroxyethyl)piperazine; branched polyethyleneimines having primary and tertiary amino groups; and organic / inorganic compounds having a tertiary amino group as a substituent. Such first acidic gas adsorbents can be used alone or in combination. Among the first acidic gas adsorbents, preferred are methyldiethylamine, branched polyethyleneimines, and organic / inorganic compounds having a tertiary amino group as a substituent.

[0016] CO ２The second acidic gas adsorbent capable of adsorbing the above-mentioned acidic gas typically contains a primary amino group and / or a secondary amino group. The second acidic gas adsorbent contains a primary amino group and / or a secondary amino group, but does not contain a tertiary amino group. Examples of the second acidic gas adsorbent include nitrogen-containing compounds having a primary amino group and / or a secondary amino group. Specific examples of nitrogen-containing compounds having primary amino groups and / or secondary amino groups include primary amines such as monoethanolamine and polyvinylamine; secondary amines such as diethanolamine, cyclic amines, and N-(3-aminopropyl)diethanolamine; ethyleneamine compounds such as tetraethylenepentamine; aminosilane coupling agents such as aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, and polyethyleneimine-trimethoxysilane; ethyleneimine; linear polyethyleneimine; polyamidoamines having primary amino groups and / or secondary amino groups; polyvinylamines having primary amino groups and / or secondary amino groups; and organic / inorganic compounds having primary amino groups and / or secondary amino groups as substituents. Such second acidic gas adsorbents can be used alone or in combination. Among the second acidic gas adsorbents, preferred are monoethanolamine, cyclic amine, diethanolamine, tetraethylenepentamine, ethyleneimine, linear polyethyleneimine, and organic / inorganic compounds having primary amino groups and / or secondary amino groups as substituents.

[0017] In one embodiment, the first acidic gas adsorbent is methyldiethylamine, and the second acidic gas adsorbent is polyethyleneimine. When the first acidic gas adsorbent and the second acidic gas adsorbent are used in the specific combination, CO ２ Adsorption capacity and CO ２ This ensures a good balance between the adsorption force and the adsorption capacity, and further improves the adsorption performance of the entire acid gas adsorption device.

[0018] In one embodiment, the acidic gas adsorption device 100 includes an acidic gas adsorption unit 1 including a first adsorption unit 11 and a second adsorption unit 12; and a single case 2. The case 2 houses the acidic gas adsorption unit 1. In other words, the single case 2 houses the first adsorption unit 11 and the second adsorption unit 12 together. When the first adsorption unit and the second adsorption unit are housed together in a single case, the acidic gas adsorption device can be made smaller than when the first adsorption unit and the second adsorption unit are housed in different cases, thereby reducing equipment costs and potentially increasing the amount of acidic gas recovered per area.

[0019] In the illustrated example, the case 2 has a cylindrical shape extending in the fluid passage direction. The upstream end of the case 2 in the fluid passage direction is configured as a first opening 21. The downstream end of the case 2 in the fluid passage direction is configured as a second opening 22. The acidic gas adsorption unit 1 is disposed between the first opening 21 and the second opening 22 in the internal space of the case 2. The first adsorption unit 11 is disposed between the first opening 21 and the second adsorption unit 12. The second adsorption unit 12 is disposed on the opposite side of the first adsorption unit 11 from the first opening 21. The first opening 21 and the second opening 22 are each capable of allowing fluid to pass through. A fluid containing acidic gas is supplied to the first adsorption unit 11 via the first opening 21. The fluid that has passed through the first adsorption unit 11 and the second adsorption unit 12 in order is discharged from the second opening 22.

[0020] The first adsorption section 11 includes the upstream end face 1a of the acidic gas adsorption section 1 in the fluid passage direction. The second adsorption section 12 includes the downstream end face 1b of the acidic gas adsorption section 1 in the fluid passage direction. The fluid passage direction is typically perpendicular to each of the upstream end face 1a and the downstream end face 1b of the acidic gas adsorption section 1. The dimension of the acidic gas adsorption section 1 in the fluid passage direction is not particularly limited as long as the fan driving power does not increase due to pressure loss, and is, for example, 0.5 m or more, preferably 0.6 m or more, and for example, 2.0 m or less, preferably 1.0 m or less. The dimension of the acidic gas adsorption section 1 in the direction perpendicular to the fluid passage direction is not particularly limited, and is, for example, 1.5 m or more, preferably 2.0 m or more, and for example, 4.0 m or less, preferably 3.0 m or less.

[0021] When the total length of the case 2 in the fluid passage direction is taken as 100%, the dimensional proportion of each of the first adsorption section 11 and the second adsorption section 12 is, for example, 10% to 90%, preferably 20% to 80%, and more preferably 30% to 70%. If the dimensional proportions of each of the first adsorption section and the second adsorption section to the case are within such ranges, the acid gas adsorption device as a whole can maintain excellent adsorption power while ensuring a large acid gas adsorption capacity.

[0022] The distance between the first opening 21 and the upstream end face 1 a of the first adsorption unit 11 in the fluid passage direction is, for example, 1 cm or more, preferably 5 cm or more, and more preferably 10 cm or more. The distance between the downstream end face 1 b of the second adsorption unit 12 and the second opening 22 in the fluid passage direction is, for example, 1 cm or more, preferably 5 cm or more, and more preferably 10 cm or more. By ensuring such a distance between the first opening and the upstream end face and / or the downstream end face and the second opening, the effects of turbulence that may occur in the first opening and the second opening can be reduced, and an increase in energy costs due to pressure loss in the first adsorption unit and the second adsorption unit can be suppressed.

[0023] The acidic gas adsorption unit 1 may be configured such that the first adsorption unit 11 and the second adsorption unit 12 are integrated as shown in Fig. 2 , or may be divided into the first adsorption unit 11 and the second adsorption unit 12 in the fluid passage direction as shown in Fig. 1 . In one embodiment, the acidic gas adsorption unit 1 is divided into the first adsorption unit 11 and the second adsorption unit 12 in the fluid passage direction, and the first adsorption unit 11 and the second adsorption unit 12 are configured as separate units (see Fig. 1 ). If the first adsorption unit and the second adsorption unit are separated, the first adsorption unit and the second adsorption unit can be manufactured separately more smoothly than when the first adsorption unit and the second adsorption unit are manufactured as an integrated unit.

[0024] A gap may be formed between the first adsorption unit 11 and the second adsorption unit 12 in the fluid passage direction. Generally, in an acidic gas adsorption unit, the fluid flows easily near the center and less easily in the outer portions. In this regard, if a gap is formed between the first adsorption unit and the second adsorption unit, the variation in the fluid flow rate in the acidic gas adsorption unit can be reduced. In the fluid passage direction, the dimension of the gap is, for example, 30% or less, preferably 10% or less, of the total length of the acidic gas adsorption unit in the fluid passage direction (the sum of the dimensions of the first adsorption unit and the second adsorption unit in the fluid passage direction). If the dimension of the gap is equal to or less than the above upper limit, the fluid can be prevented from stagnation between the first adsorption unit and the second adsorption unit, and the fluid can flow smoothly from the first adsorption unit to the second adsorption unit.

[0025] The dimensions of the first adsorption section 11 and the second adsorption section 12 in the fluid passage direction may be any appropriate value depending on the acidic gas adsorbent used. In one embodiment, the dimension of the first adsorption section 11 in the fluid passage direction is longer than the dimension of the second adsorption section 12. In the fluid passage direction, the dimension of the first adsorption section 11 is, for example, 50% or more, preferably 60% or more, and, for example, 90% or less, preferably 80% or less, of the total length of the acidic gas adsorption section 1 (the sum of the dimensions of the first adsorption section and the second adsorption section). In the fluid passage direction, the dimension of the second adsorption section 12 is, for example, 10% or more, preferably 30% or more, and, for example, 50% or less, preferably 40% or less, of the total length of the acidic gas adsorption section 1. When the dimensions of the first adsorption section and / or the second adsorption section are within the above range, the adsorption efficiency of the acidic gas can be stably improved.

[0026] As shown in FIG. 3 , in one embodiment, the acidic gas adsorption unit 1 further includes a third adsorption unit 13 disposed between the first adsorption unit 11 and the second adsorption unit 12. This allows the first adsorption unit, the second adsorption unit, and the third adsorption unit to be manufactured separately and more smoothly than when the acidic gas adsorption unit is manufactured as an integrated unit. A gap may be formed between the first adsorption unit 11 or the second adsorption unit 12 and the third adsorption unit 13 in the fluid passage direction. The range of the size of the gap between the first adsorption unit 11 or the second adsorption unit 12 and the third adsorption unit 13 is the same as the range of the size of the gap between the first adsorption unit 11 and the second adsorption unit 12 described above. As shown in FIG. 3 , the third adsorption unit 13 may contain the same acidic gas adsorbent as the first adsorption unit 11. Alternatively, as shown in FIG. 4 , the third adsorption unit 13 may contain a mixture of the acidic gas adsorbent of the first adsorption unit 11 and the acidic gas adsorbent of the second adsorption unit 12.

[0027] In one embodiment, the third adsorption section 13 includes an acidic gas adsorbent different from the acidic gas adsorbent of the first adsorption section 11 and the acidic gas adsorbent of the second adsorption section 12 (see FIG. 4 ). The third adsorption section 13 preferably includes a third acidic gas adsorbent. The adsorption power of the third acidic gas adsorbent is greater than that of the first acidic gas adsorbent and less than that of the second acidic gas adsorbent. The adsorption capacity of the third acidic gas adsorbent is less than that of the first acidic gas adsorbent and greater than that of the second acidic gas adsorbent. According to this configuration, the first acidic gas adsorbent, the third acidic gas adsorbent, and the second acidic gas adsorbent are arranged so that the adsorption power of the acidic gas increases in this order. Therefore, CO in the acidic gas adsorption section ２ Adsorption capacity and CO ２ This ensures a better balance between the adsorption force and the adsorption capacity, and further improves the efficiency of adsorption of acidic gases in the acidic gas adsorption device.

[0028] Third acid gas adsorbent CO ２ The adsorption capacity is, for example, 1.2 mol / kg-adsorbent or more, preferably 1.7 mol / kg-adsorbent or more, and more preferably 2.2 mol / kg-adsorbent or more. ２ The concentration of the third acidic gas adsorbent is, for example, 150 ppm or less, preferably 125 ppm or less, more preferably 100 ppm or less, and is, for example, 75 ppm or more. A specific example of the third acidic gas adsorbent is polyethyleneimine.

[0029] As shown in FIG. 5 , the first suction section 11 may be divided into multiple first blocks 11a in a direction perpendicular to the fluid passage direction. In other words, the first suction section 11 is composed of multiple first blocks 11a arranged in a direction perpendicular to the fluid passage direction. This allows the first suction section to be constructed by manufacturing relatively small first blocks. Therefore, the first suction section can be manufactured more easily than when the first suction section is manufactured in bulk. The dimension of the first block 11a in the fluid passage direction is, for example, 0.10 m or more, preferably 0.15 m or more, and, for example, 0.30 m or less, preferably 0.20 m or less. The dimension of the first block 11a in the direction perpendicular to the fluid passage direction is, for example, 0.10 m or more, preferably 0.15 m or more, and, for example, 0.80 m or less, preferably 0.60 m or less.

[0030] Among the multiple first blocks 11a, adjacent first blocks 11a may have a gap therebetween or may be in contact with each other in a direction perpendicular to the fluid passage direction. In the illustrated example, the first adsorption unit 11 is divided into four in a direction perpendicular to the fluid passage direction (the vertical direction in the plane of the drawing). The number of divisions of the first adsorption unit in the direction perpendicular to the fluid passage direction is not limited to this. Furthermore, the first adsorption unit 11 may also be divided into multiple parts in a direction perpendicular to the fluid passage direction (the depth direction in the plane of the drawing). The number of divisions of the first adsorption unit in the direction perpendicular to the fluid passage direction is, for example, 2 to 300. Furthermore, all of the multiple first blocks 11a may contain the same first acidic gas adsorbent, or some of the multiple first blocks 11a may contain different first acidic gas adsorbents.

[0031] In one embodiment, the second suction section 12 is divided into a plurality of second blocks 12a in a direction perpendicular to the fluid passage direction. The second suction section 12 is composed of a plurality of second blocks 12a arranged in a direction perpendicular to the fluid passage direction. This allows the second suction section to be constructed by manufacturing relatively small second blocks, making it easy to manufacture the second suction section. The dimensional range of the second blocks 12a is the same as the dimensional range of the first blocks 11a described above.

[0032] Adjacent second blocks 12a among the plurality of second blocks 12a may have gaps therebetween or may be in contact with each other in a direction perpendicular to the fluid passage direction. In the illustrated example, the second adsorption unit 12 is divided into four in a direction perpendicular to the fluid passage direction (the vertical direction in the plane of the drawing). The number of divisions of the second adsorption unit in the direction perpendicular to the fluid passage direction is not limited to this. Furthermore, the second adsorption unit 12 may also be divided into multiple parts in a direction perpendicular to the fluid passage direction (the depth direction in the plane of the drawing). The number of divisions of the second adsorption unit in the direction perpendicular to the fluid passage direction is, for example, 2 to 300, and is preferably the same as the number of divisions of the first adsorption unit. Furthermore, all of the plurality of second blocks 12a may contain the same second acidic gas adsorbent, or some of the plurality of second blocks 12a may contain different second acidic gas adsorbents.

[0033] In one embodiment, the third suction section 13 is divided into a plurality of third blocks 13a in a direction perpendicular to the fluid passage direction. The third suction section 13 is composed of a plurality of third blocks 13a arranged in a direction perpendicular to the fluid passage direction. This allows the third suction section to be constructed using relatively small third blocks, making it easy to manufacture the third suction section. The dimensional range of the third blocks 13a is the same as the dimensional range of the first blocks 11a described above.

[0034] Among the plurality of third blocks 13a, adjacent third blocks 13a may have a gap therebetween or may be in contact with each other in a direction perpendicular to the fluid passage direction. In the illustrated example, the third suction portion 13 is divided into four in a direction perpendicular to the fluid passage direction (the vertical direction in the plane of the drawing). The number of divisions of the third suction portion in the direction perpendicular to the fluid passage direction is not limited to this. Furthermore, the third suction portion 13 may also be divided into multiple parts in a direction perpendicular to the fluid passage direction (the depth direction in the plane of the drawing). The number of divisions of the third suction portion in the direction perpendicular to the fluid passage direction is, for example, 2 to 300, and is preferably the same as the number of divisions of the first suction portion.

[0035] In addition, all of the plurality of third blocks 13a may contain the same acidic gas adsorbent, or some of the plurality of third blocks 13a may contain different acidic gas adsorbents. In Fig. 6, in the third adsorption section 13, the third block 13a located in the central portion and the third block 13a located in the outer portion contain different acidic gas adsorbents. More specifically, in the third adsorption section 13, the third block 13a located in the central portion contains the above-mentioned third acidic gas adsorbent, and the third block 13a located in the outer portion contains the above-mentioned second acidic gas adsorbent.

[0036] 3 to 6 , only the third adsorption section 13 is disposed between the first adsorption section 11 and the second adsorption section 12; however, additional adsorption sections may be provided between the first adsorption section 11 and the second adsorption section 12. Although not shown, the acidic gas adsorption section 1 may include the third to nth adsorption sections between the first adsorption section 11 and the second adsorption section 12. The nth adsorption section includes an nth acidic gas adsorbent. Similarly to the above, each of these nth adsorption sections may be divided into multiple nth blocks in a direction perpendicular to the fluid passage direction. n is, for example, 4 to 30. When the acidic gas adsorption section includes the third to nth adsorption sections, it is preferable that the adsorption power of the acidic gas adsorbent included in the adsorption section located further downstream in the fluid passage direction is greater.

[0037] 1 to 6 , the acidic gas adsorption unit 1 housed in one case 2 includes a first adsorption unit 11 and a second adsorption unit 12, but the arrangement of the first adsorption unit and the second adsorption unit is not limited to this. As shown in FIG. 7 , two cases 2 may be connected in series in the fluid flow direction, with the first adsorption unit 11 housed in the upstream case 2 and the second adsorption unit 12 housed in the downstream case 2. This also improves the adsorption performance of the acidic gas adsorption device, as in the above embodiment.

[0038] The specific configuration of the acidic gas adsorption section will be described below.

[0039] B. Acidic Gas Adsorption Unit As described above, the acidic gas adsorption unit 1 includes at least the first adsorption unit 11 and the second adsorption unit 12. The acidic gas adsorption unit 1 may also include the third adsorption unit 13 to the nth adsorption unit. The first to nth adsorption units typically have the same configuration, except for the type of acidic gas adsorbent. The first adsorption unit 11 (integrally formed) shown in FIG. 1 and the first block 11a shown in FIG. 5 have the same configuration, except for their different sizes. Therefore, the configuration of the first block 11a shown in FIG. 5 will be described in detail below.

[0040] In one embodiment, as shown in FIG. 8, the first block 11a includes a plurality of adsorbent layers 71.

[0041] The multiple adsorbent layers 71 are stacked at intervals in the thickness direction. In the illustrated example, five adsorbent layers 71 are arranged in parallel, but the number of adsorbent layers 71 is not limited to this. The number of adsorbent layers 71 is, for example, 5 or more, preferably 10 or more, and more preferably 20 or more. The interval between adjacent adsorbent layers 71 among the multiple adsorbent layers 71 is, for example, 0.5 cm or more and 1.5 cm or less.

[0042] Each of the plurality of adsorbent layers 71 includes a flexible fiber member 73 and a plurality of pellet-shaped adsorbent materials 72 .

[0043] The flexible fiber member 73 allows gas to pass through while restricting the passage of the pellet-shaped adsorbent material. The flexible fiber member 73 is typically formed in a hollow (bag-like) shape capable of accommodating a plurality of pellet-shaped adsorbent materials 72. The flexible fiber member 73 may be a woven fabric or a nonwoven fabric. Examples of materials for the flexible fiber member 73 include organic fibers and natural fibers, and preferred examples include polyethylene terephthalate fibers, polyethylene fibers, and cellulose-based fibers. The thickness of the flexible fiber member 73 is, for example, 25 μm or more and 500 μm or less.

[0044] A plurality of pellet-shaped adsorbents 72 are packed inside a flexible fiber member 73 having a hollow (bag-shaped) shape. The pellet-shaped adsorbents 72 function as acidic gas adsorbents, typically carbon dioxide adsorbents. Examples of materials for the pellet-shaped adsorbents 72 include materials modified with the above-described acidic gas adsorbents (first acidic gas adsorbent or second acidic gas adsorbent), preferably cellulose modified with the above-described acidic gas adsorbent (first acidic gas adsorbent or second acidic gas adsorbent), and more preferably nanofiberized cellulose modified with the above-described acidic gas adsorbent (first acidic gas adsorbent or second acidic gas adsorbent). The average primary particle diameter of the pellet-shaped adsorbents 72 is, for example, 60 μm or more and 1200 μm or less. The loading ratio of the pellet-shaped adsorbents 72 in the adsorbent layer 71 may be any appropriate value.

[0045] The illustrated acid gas adsorption device 1 further includes a plurality of spacers 74. The spacers 74 are sandwiched between adjacent adsorbent layers 71 among the plurality of adsorbent layers 71. This ensures a stable spacing between adjacent adsorbent layers. In one embodiment, the plurality of adsorbent layers 71 and the plurality of spacers 74 are arranged in a generally zigzag shape when viewed from a direction perpendicular to the thickness direction of the adsorbent layer 71 (the depth direction of the paper in FIG. 1 ).

[0046] An example of such an acid gas adsorption device 1 is the gas separation unit described in WO 2014 / 170184, the entire disclosure of which is incorporated herein by reference.

[0047] In another embodiment, as shown in Figures 9 and 10, the first block 11a typically includes a substrate 3 and an acidic gas adsorption layer 4. The structure of the substrate 3 is not particularly limited, and examples thereof include a honeycomb structure, a filter structure such as a filter cloth, and a pellet structure. The acidic gas adsorption layer 4 is not particularly limited as long as it is disposed on the surface of the substrate 3.

[0048] B-1. Substrate (Honeycomb Substrate) In one embodiment, the substrate 3 is a honeycomb substrate 3a. The honeycomb substrate 3a has partition walls 32 that define a plurality of cells 33. The cells 33 extend in the longitudinal direction (axial direction) of the honeycomb substrate 3a from the first end face E1 (inlet end face) to the second end face E2 (outlet end face) of the honeycomb substrate 3a (see FIG. 10). The cells 33 have any appropriate shape in a cross section perpendicular to the longitudinal direction of the honeycomb substrate 3a. Examples of the cross-sectional shape of the cells include a triangle, a rectangle, a pentagon, a polygon with hexagons or more, a circle, and an ellipse. The cross-sectional shapes and sizes of the cells may all be the same, or at least some may be different. Among such cross-sectional shapes of the cells, a hexagon or a quadrangle is preferred, and a square, a rectangle, or a hexagon is more preferred.

[0049] The cell density (i.e., the number of cells 33 per unit area) in the cross section perpendicular to the longitudinal direction of the honeycomb substrate can be appropriately set depending on the purpose. For example, the cell density is 4 cells / cm ２ ~320 cells / cm ２ If the cell density is in this range, the strength and effective GSA (geometric surface area) of the honeycomb substrate can be sufficiently ensured.

[0050] The honeycomb substrate 3a may have any suitable shape (overall shape). Examples of the shape of the honeycomb substrate include a cylindrical shape with a circular bottom, an elliptical cylindrical shape with an elliptical bottom, a rectangular pillar shape with a polygonal bottom, and a pillar shape with an irregular bottom. The honeycomb substrate 3a in the illustrated example has a rectangular pillar shape. The outer diameter and length of the honeycomb substrate can be appropriately set depending on the purpose. Although not shown, the honeycomb substrate may have a hollow region in the center in a cross section perpendicular to the longitudinal direction.

[0051] The honeycomb substrate 3 a typically includes an outer wall 31 and partition walls 32 located inside the outer wall 31. In the illustrated example, the outer wall 31 and the partition walls 32 are integrally formed. However, the outer wall 31 and the partition walls 32 may be separate bodies.

[0052] In the illustrated example, the outer wall 31 has a rectangular cylindrical shape. The thickness of the outer wall 31 can be set arbitrarily and appropriately. The thickness of the outer wall 31 is, for example, 0.1 mm to 10 mm.

[0053] The partition walls 32 define a plurality of cells 33. More specifically, the partition walls 32 include first partition walls 32a and second partition walls 32b that are perpendicular to each other, and the first partition walls 32a and the second partition walls 32b define the plurality of cells 33. The cross-sectional shape of the cells 33 is substantially rectangular. Note that the configuration of the partition walls is not limited to the above-described partition walls 32. The partition walls may include first partition walls extending in the radial direction and second partition walls extending in the circumferential direction, which define the plurality of cells.

[0054] The thickness of the partition walls 32 can be appropriately set depending on the application of the acidic gas adsorption device. The thickness of the partition walls 32 is typically thinner than the thickness of the outer walls 31. The thickness of the partition walls 32 is, for example, 0.03 mm to 0.6 mm. The thickness of the partition walls is measured by cross-sectional observation using, for example, a scanning electron microscope (SEM). When the thickness of the partition walls is in this range, the mechanical strength of the honeycomb substrate can be made sufficient, and the opening area (the total area of ​​the cells in the cross section) can be made sufficient.

[0055] The porosity of the partition walls 32 can be appropriately set depending on the purpose. The porosity of the partition walls 32 is, for example, 15% or more, preferably 20% or more, and for example, 70% or less, preferably 45% or less. The porosity can be measured by, for example, mercury intrusion porosimetry. The bulk density of the partition walls 32 can be appropriately set depending on the purpose. The bulk density is, for example, 0.10 g / cm ３ or more, preferably 0.20 g / cm ３ or more, for example, 0.60 g / cm ３ or less, preferably 0.50 g / cm ３ The bulk density can be measured by, for example, mercury intrusion porosimetry.

[0056] A representative example of a material for forming the partition walls 32 is ceramics. Examples of ceramics include silicon carbide, silicon-silicon carbide composite materials, cordierite, mullite, alumina, silicon nitride, spinel, silicon carbide-cordierite composite materials, lithium aluminum silicate, and aluminum titanate. The materials for forming the partition walls can be used alone or in combination. Among the materials for forming the partition walls, preferred examples include cordierite, alumina, mullite, silicon carbide, silicon-silicon carbide composite materials, and silicon nitride, and more preferred examples include silicon carbide and silicon-silicon carbide composite materials.

[0057] Such a honeycomb-shaped substrate 3a is typically produced by the following method. First, a binder and water or an organic solvent are added, if necessary, to a material powder containing the above-mentioned ceramic powder, and the resulting mixture is kneaded to form a clay. The clay is then molded into a desired shape (typically by extrusion molding), dried, and fired as needed to produce the honeycomb-shaped substrate 3a. When firing, the firing is performed at, for example, 1200°C to 1500°C. The firing time is, for example, 1 hour or more and 20 hours or less.

[0058] B-2. Acidic Gas Adsorption Layer (Carbon Dioxide Adsorption Layer) In one embodiment, the acidic gas adsorption layer 4 is formed on the surface of the partition wall 32. In the honeycomb substrate 3a, the flow paths 34 are formed in the portions (typically the central portions) in the cross section of the cells 33 where the acidic gas adsorption layer 4 is not formed. The acidic gas adsorption layer 4 may be formed on the entire inner surface of the partition wall 32 (i.e., so as to surround the flow paths 34) as in the illustrated example, or may be formed on a portion of the surface of the partition wall. When the acidic gas adsorption layer 4 is formed on the entire inner surface of the partition wall 32, the acidic gas (typically, CO ２ ) can be improved in adsorption efficiency.

[0059] Like the cells 33, the flow paths 34 extend from a first end face E1 (inlet end face) to a second end face E2 (outlet end face). Examples of the cross-sectional shape of the flow paths 34 include the same cross-sectional shapes as the cells 33 described above, preferably hexagonal or quadrangular, and more preferably square, rectangular, or hexagonal. The cross-sectional shapes and sizes of the flow paths 34 may all be the same, or at least some may be different. A fluid containing an acidic gas is typically supplied to the cells 33 (more specifically, the flow paths 34) in the adsorption step described below.

[0060] The acidic gas adsorption layer 4 includes an acidic gas adsorbent corresponding to the acidic gas to be adsorbed. The acidic gas adsorption layer 4 included in the first adsorption unit 11 (first block 11a) includes the first acidic gas adsorbent described above. The acidic gas adsorption layer 4 included in the second adsorption unit 12 (second block 12a) includes the second acidic gas adsorbent described above.

[0061] In one embodiment, the acidic gas adsorbent layer 4 further includes a porous carrier in addition to the above-described acidic gas adsorbent (first acidic gas adsorbent or second acidic gas adsorbent). In this case, the acidic gas adsorbent is typically supported on the porous carrier and faces the flow path. When the acidic gas adsorbent layer includes a porous carrier, it is possible to prevent the acidic gas adsorbent from falling off from the acidic gas adsorbent layer during the adsorption step and / or desorption step.

[0062] The porous support can form mesopores in the acidic gas adsorbent layer. Examples of the porous support include metal-organic frameworks (MOFs) such as MOF-74, MOF-200, and MOF-210; activated carbon; nitrogen-doped carbon; mesoporous silica; mesoporous alumina; zeolites; carbon nanotubes; and fluorinated resins such as polyvinylidene fluoride (PVDF). Preferred examples include metal-organic frameworks (MOFs), activated carbon, PVDF, zeolites, mesoporous silica, and mesoporous alumina. The porous support can be used alone or in combination. Preferably, the porous support is made of a material different from that of the acidic gas adsorbent.

[0063] The BET specific surface area of ​​the porous carrier is, for example, 50 m２ / g or more, preferably 500m ２ When the surface area of ​​the porous carrier is equal to or greater than the lower limit, the acidic gas adsorbent can be stably supported, and the efficiency of adsorption of acidic gases can be improved. The upper limit of the BET specific surface area of ​​the porous carrier is typically 2000 m ２ / g or less.

[0064] When the acidic gas adsorbent layer contains an acidic gas adsorbent and a porous carrier, the total content of the acidic gas adsorbent and the porous carrier in the acidic gas adsorbent layer is, for example, 30% by mass or more, preferably 50% by mass or more, and for example, 100% by mass or less, preferably 99% by mass or less. The content of the acidic gas adsorbent in the acidic gas adsorbent layer is, for example, 30% by mass or more, preferably 50% by mass or more, and for example, 99% by mass or less. The content of the porous carrier is, for example, 0.01 parts by mass or more, preferably 0.3 parts by mass or more, and for example, 0.7 parts by mass or less, preferably 0.5 parts by mass or less, relative to 1 part by mass of the acidic gas adsorbent. When the content of the porous carrier is in the above range, the acidic gas adsorbent can be supported more stably.

[0065] Alternatively, the acidic gas adsorbent layer may be composed solely of an acidic gas adsorbent. In this case, the acidic gas adsorbent is directly supported on the partition wall 32 and faces the flow path. When the acidic gas adsorbent layer is composed solely of an acidic gas adsorbent, the content of the acidic gas adsorbent in the acidic gas adsorbent layer is typically 95.0 mass% or more and 100 mass% or less. When the content of the acidic gas adsorbent is within the above range, excellent acidic gas adsorption efficiency can be stably ensured.

[0066] Such an acidic gas adsorbent layer is typically produced by the following method. The above-described acidic gas adsorbent is dissolved in a solvent to prepare a solution of the acidic gas adsorbent. If necessary, the above-described porous carrier is added to the solvent. The order of adding the acidic gas adsorbent and the porous carrier is not particularly limited. The acidic gas adsorbent solution is then applied to a substrate (specifically, a partition wall), and the coating is dried and, if necessary, sintered to form an acidic gas adsorbent layer.

[0067] C. Acidic Gas Recovery Method Next, a method for recovering acidic gas using an acidic gas adsorption device according to one embodiment of the present invention will be described. The acidic gas recovery method typically includes an adsorption step and a desorption step, in that order.

[0068] In the adsorption step, a fluid containing an acidic gas is supplied to the acidic gas adsorption unit 1, which has been adjusted to a predetermined adsorption temperature. At this time, the fluid containing the acidic gas first flows into the first adsorption unit 11 (more specifically, the flow path 34 of the first block 11a). As a result, the first acidic gas adsorbent contained in the first adsorption unit 11 adsorbs the acidic gas (typically CO ) at a relatively high concentration. ２ The second block 12a adsorbs a relatively large amount of acidic gas from the fluid containing the acidic gas. The fluid with a reduced acidic gas concentration then flows into the second adsorption section 12 (more specifically, the flow path 34 of the second block 12a). This allows the second acidic gas adsorbent contained in the second adsorption section 12 to adsorb the acidic gas (typically CO) at a relatively low concentration. ２ This allows the acid gas to be efficiently adsorbed from the fluid supplied to the acid gas adsorption section.

[0069] The temperature (adsorption temperature) of the acidic gas adsorption section in the adsorption step is, for example, 0°C or higher, preferably 10°C or higher, and for example, 50°C or lower, preferably 40°C or lower. In one embodiment, the adsorption temperature is the same as the ambient temperature. The duration of the adsorption step (adsorption time) is, for example, 15 minutes or longer, preferably 30 minutes or longer, and for example, 3 hours or shorter, preferably 2 hours or shorter. When the adsorption temperature and / or adsorption time are within the above ranges, the acidic gas adsorbent can efficiently adsorb acidic gases.

[0070] The acidic gas adsorption rate in the adsorption step (=100-(acidic gas concentration in the fluid that has passed through the acidic gas adsorption section / acidic gas concentration in the fluid before being supplied to the acidic gas adsorption section×100)) is, for example, 60% or more, preferably 75% or more, more preferably 80% or more, and for example, 90% or less.

[0071] Next, in the desorption step, typically, the acidic gas adsorption unit 1 is heated to a desorption temperature that exceeds the adsorption temperature. More specifically, in the desorption step, the temperature of the acidic gas adsorption unit 1 is raised to the desorption temperature and then maintained at the desorption temperature for a predetermined desorption time. As a result, the acidic gas adsorbed by the acidic gas adsorbents (the first acidic gas adsorbent and the second acidic gas adsorbent) in the adsorption step is desorbed from the acidic gas adsorbents. Therefore, the desorbed acidic gas can be recovered.

[0072] In one embodiment, in the desorption step, the desorbed gas is supplied to the acidic gas adsorption section 1, and the desorbed acidic gas is recovered together with the desorbed gas by passing the desorbed gas through the first adsorption section 11 and the second adsorption section 12 in order. The gas recovered in the desorption step may be referred to as the recovered gas. Preferably, the desorbed gas is the recovered gas previously recovered by the acidic gas adsorption device. By using the recovered gas as the desorbed gas, the acidic gas concentration in the recovered gas can be improved. Note that the acidic gas can also be recovered in the desorption step without using the desorbed gas. For example, the desorbed acidic gas may be sucked and recovered using a vacuum pump. Alternatively, the desorbed gas and the vacuum pump can be used in combination.

[0073] The temperature (desorption temperature) of the acidic gas adsorption section in the desorption step is, for example, 70°C or higher, preferably 80°C or higher, and for example, 200°C or lower, preferably 110°C or lower. The duration of the desorption step (the desorption time during which the acidic gas adsorption section is maintained at the desorption temperature) is, for example, 1 minute or higher, preferably 5 minutes or higher, and for example, 1 hour or lower, preferably 30 minutes or lower. When the desorption temperature and / or desorption time are within the above ranges, the acidic gas can be sufficiently desorbed from each of the first acidic gas adsorbent and the second acidic gas adsorbent.

[0074] In this way, the acid gas can be efficiently recovered. The adsorption step and the desorption step are preferably carried out repeatedly in this order.

[0075] The acid gas adsorption device according to the embodiment of the present invention is used for separating and recovering acid gases, and can be particularly suitably used in a carbon dioxide capture, utilization, and storage (CCUS) cycle.

[0076] 1 Acidic gas adsorption section 11 First adsorption section 12 Second adsorption section

Claims

1. An acidic gas adsorption device comprising: an acidic gas adsorption unit containing an acidic gas adsorbent capable of adsorbing acidic gases and through which a fluid can pass in a predetermined direction; and a single case, wherein the acidic gas adsorption unit comprises: a first adsorption unit containing a first acidic gas adsorbent that has a relatively low adsorption power for adsorbing acidic gases and a large adsorption capacity for acidic gases; and a second adsorption unit that is arranged downstream of the first adsorption unit in the direction through which the fluid passes, and contains a second acidic gas adsorbent that has a relatively high adsorption power for adsorbing acidic gases and a small adsorption capacity for acidic gases; and wherein the single case collectively houses the first adsorption unit and the second adsorption unit.

2. The acid gas adsorption device according to claim 1, wherein the acid gas is carbon dioxide.

3. The acid gas adsorption device according to claim 2, wherein the equilibrium acid gas concentration of the first acid gas adsorbent exceeds 100 ppm, and the equilibrium acid gas concentration of the second acid gas adsorbent is 100 ppm or less.

4. The acid gas adsorption device according to claim 3, wherein the first acid gas adsorbent contains a tertiary amino group, and the second acid gas adsorbent contains a primary amino group and / or a secondary amino group.

5. An acid gas adsorption device as described in any one of claims 1 to 4, wherein the first adsorption section is divided into multiple sections in a direction perpendicular to the direction in which the fluid passes.

6. An acid gas adsorption device as described in any one of claims 1 to 4, wherein the second adsorption section is divided into multiple sections in a direction perpendicular to the direction in which the fluid passes.