Acidic gas system

Abstract

Provided is an acidic gas system in which energy saving can be achieved for an acidic gas recovery device or acidic gas utilization equipment. An acidic gas system according to one embodiment comprises an acidic gas recovery device that recovers acidic gas or acidic gas utilization equipment that utilizes acidic gas. This acidic gas system comprises an acidic gas concentration device, a to-be-treated gas supply unit, and a concentrated gas supply unit. A to-be-treated gas including an acidic gas is supplied to the acidic gas concentration device. The acidic gas concentration device is configured so as to discharge a concentrated gas having a higher concentration of acidic gas than the to-be-treated gas. The to-be-treated gas supply unit is configured so as to supply a to-be-treated gas having an acidic gas concentration of 10 vol% or less to the acidic gas concentration device. The concentrated gas supply unit is configured so as to supply the concentrated gas from the acidic gas concentration device to the acidic gas recovery device or acidic gas utilization equipment.

Description

Acid gas system

[0001] This invention relates to an acidic gas system.

[0002] In recent years, carbon dioxide (hereinafter CO ２ Acidic gases (sometimes referred to as [specific term]) are being explored for various applications. Therefore, an acidic gas recovery device has been proposed to recover acidic gases from a gas to be treated that contains acidic gases (see, for example, Non-Patent Document 1).

[0003] Energy Procedia Volume 1, Issue 1, February 2009, Pages 195-204

[0004] In acid gas recovery devices such as those described in Non-Patent Document 1, a target gas with an acid gas concentration of 10% by volume or less is generally supplied, and the acid gas is recovered from the target gas. In such acid gas recovery devices, there is an increasing desire to reduce the energy required for acid gas recovery. The main object of the present invention is to provide an acid gas system that can achieve energy savings in acid gas recovery devices or acid gas utilization equipment.

[0005] [1] An acid gas system according to an embodiment of the present invention includes an acid gas recovery device for recovering acid gas or an acid gas utilization facility for utilizing acid gas. The acid gas system includes an acid gas concentrater, a gas to be treated supply unit, and a concentrated gas supply unit. The acid gas concentrater is supplied with a gas to be treated that contains acid gas. The acid gas concentrater is configured to discharge a concentrated gas in which the concentration of acid gas is higher than that of the gas to be treated. The gas to be treated supply unit is configured to supply the gas to be treated, in which the acid gas concentration is 10% by volume or less, to the acid gas concentrater. The concentrated gas supply unit is configured to supply the concentrated gas from the acid gas concentrater to the acid gas recovery device or the acid gas utilization facility. [2] In the acid gas system described in [1] above, the acid gas concentrater may be configured such that the acid gas concentration in the concentrated gas is 2.5 times or more than the acid gas concentration in the gas to be treated. [3] In the acid gas system described in [1] or [2] above, the acid gas concentrator may include an acid gas adsorbent capable of adsorbing acid gases. The acid gas adsorbent is capable of desorbing adsorbed acid gases when heated to a predetermined temperature or higher. [4] The acid gas system described in [3] above may further include an air supply unit. The air supply unit is configured to supply air at a predetermined temperature or higher to the acid gas concentrator as a desorbing gas for heating the acid gas adsorbent. [5] The acid gas system described in [4] above may further include a return unit. The return unit is configured to return at least a portion of the desorbing gas that has passed through the acid gas concentrator to the acid gas concentrator. [6] In the acid gas system described in any of [3] to [5] above, the acid gas concentrator may include a concentration unit. The concentration unit may have a honeycomb structure including a plurality of gas flow paths. The acid gas adsorbent may be arranged to be in contact with the gas passing through at least a portion of the plurality of gas flow paths. [7] In the acid gas system described in any of [3] to [6] above, the acid gas adsorbent may contain an inorganic compound.[8] In the acid gas system described in any of [1] to [7] above, the acid gas may include carbon dioxide gas. [9] The acid gas system described in any of [1] to [8] above may include the acid gas recovery device configured to adsorb or separate the acid gas.

[10] The acid gas system described in any of [1] to [8] above may include the acid gas utilization equipment configured to utilize the acid gas for promoting crop growth or cultivating algae.

[0006] According to embodiments of the present invention, energy conservation can be achieved in acid gas recovery equipment or acid gas utilization equipment.

[0007] Figure 1 is a schematic diagram of an acidic gas system according to one embodiment of the present invention. Figure 2 is a schematic perspective view of the concentration section of the acidic gas system of Figure 1. Figure 3 is a central cross-sectional view of the concentration section of Figure 2. Figure 4 is a schematic diagram of the concentration section of an acidic gas system according to another embodiment of the present invention. Figure 5 is a schematic diagram of the acidic gas concentration device of the acidic gas system of Figure 1.

[0008] Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the embodiments; however, these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Schematic diagram 1 of the acid gas system is a schematic diagram of the acid gas system according to one embodiment of the present invention. In one embodiment, the acid gas system 100 includes an acid gas recovery device 6 or acid gas utilization equipment 7, an acid gas concentrater 1, a gas to be treated supply unit 2, and a concentrate gas supply unit 5. The acid gas concentrater 1 is supplied with a gas to be treated that contains acid gas. The acid gas concentrater 1 is configured to discharge concentrate gas with a higher concentration of acid gas than the gas to be treated. The gas to be treated supply unit 2 is configured to supply a gas to be treated with an acid gas concentration of 10 volume% or less to the acid gas concentrater. The concentrate gas supply unit 5 is configured to supply concentrate gas from the acid gas concentrater 1 to the acid gas recovery device 6 or acid gas utilization equipment 7. The acid gas recovery device 6 is configured to recover acid gas from concentrate gas. The acid gas utilization equipment 7 is configured to utilize the acid gas contained in concentrate gas. The inventors discovered that the concentration of the acidic gas supplied to both the acidic gas recovery device and the acidic gas utilization equipment affects the energy required by those devices and equipment. Therefore, the inventors diligently studied energy conservation in acidic gas recovery devices and acidic gas utilization equipment and found that by concentrating the acidic gas upstream of the acidic gas recovery device or acidic gas utilization equipment and supplying the concentrated gas with increased acidic gas concentration to the acidic gas recovery device or acidic gas utilization equipment, the energy required by the acidic gas recovery device or acidic gas utilization equipment can be significantly reduced. More specifically, the gas to be treated supply unit supplies the gas to be treated, with an acidic gas concentration of 10% by volume or less, to the acidic gas concentrate unit, which then discharges concentrated gas with a higher acidic gas concentration than the gas to be treated. The concentrated gas discharged from the acidic gas concentrate unit is then supplied to the acidic gas recovery device or acidic gas utilization equipment by the concentrated gas supply unit. Therefore, in an acid gas recovery device, acid gas can be recovered from concentrated gas in an energy-efficient manner, or in an acid gas utilization facility, the acid gas contained in concentrated gas can be utilized in an energy-efficient manner.

[0010] In one embodiment, the acid gas concentrater 1 is configured such that the ratio of the acid gas concentration in the concentrate to the acid gas concentration in the gas to be treated is within the following range: The acid gas concentration in the concentrate is, for example, 2.0 times or more, preferably 2.5 times or more, than the acid gas concentration in the gas to be treated. When the ratio of the acid gas concentration in the concentrate to the acid gas concentration in the gas to be treated (hereinafter sometimes referred to as the concentration ratio) is within this range, energy saving in the acid gas recovery device or acid gas utilization equipment can be stably achieved. In particular, when the concentration ratio is 2.5 times or more, energy saving can be achieved for the entire acid gas system.

[0011] The acidic gas concentration in the gas to be treated is preferably 10% by volume or less. On the other hand, the acidic gas concentration in the gas to be treated is, for example, 0.04% by volume or more, preferably 1% by volume or more. The acidic gas concentration in the concentrated gas is, for example, 0.1% by volume or more, preferably 3% by volume or more, more preferably 10% by volume or more. On the other hand, the acidic gas concentration in the concentrated gas is, for example, 100% by volume or less.

[0012] In one embodiment, the acid gas concentrate 1 includes an acid gas adsorbent capable of adsorbing acid gases. The acid gas adsorbent can desorb the adsorbed acid gas when heated to a predetermined temperature or higher. With this configuration, the acid gas concentrate can stably discharge a concentrated gas in which the concentration of acid gas is higher than that of the gas to be treated.

[0013] In one embodiment, the acid gas system 100 further includes an air supply unit 3. The air supply unit 3 is configured to supply air at a predetermined temperature or higher to the acid gas concentrate 1 as a desorption gas for heating the acid gas adsorbent. With this configuration, the acid gas adsorbent contained in the acid gas concentrate can be energetically heated efficiently by air. Therefore, acid gas can be desorbed from the acid gas adsorbent with energy savings, and as a result, the acid gas concentrate can efficiently discharge the concentrated gas.

[0014] In one embodiment, the acid gas system 100 further includes a return unit 4. The return unit 4 is configured to return at least a portion of the desorbed gas that has passed through the acid gas concentrater 1 to the acid gas concentrater 1. With this configuration, the thermal energy remaining in the desorbed gas that has passed through the acid gas concentrater can be effectively utilized to raise the temperature of the acid gas adsorbent. Therefore, the acid gas can be desorbed from the acid gas adsorbent with less energy.

[0015] B. Details of the Acid Gas System Next, the details of the acid gas system 100 will be described with reference to Figures 1 to 5. As shown in Figure 1, in one embodiment, the acid gas system 100 includes an acid gas concentrater 1, a gas to be treated supply unit 2, an air supply unit 3, a return unit 4, a concentrated gas supply unit 5, and an acid gas recovery unit 6. The acid gas system 100 may also include an acid gas utilization unit 7 instead of the acid gas recovery unit 6.

[0016] B-1. Acid Gas Concentrator B-1-1. Acid Gas Adsorbent The acid gas concentrate 1 includes an acid gas adsorbent capable of adsorbing and desorbing acid gases, as described above.

[0017] As an acidic gas, for example, carbon dioxide (CO2) ２ Examples include CO2 gas, hydrogen sulfide gas, sulfur dioxide gas, nitrogen dioxide gas, dimethyl sulfide (DMS) gas, and hydrogen chloride gas. In one embodiment, the acidic gas is CO2. ２ It contains gas. The acidic gas adsorbent may be capable of adsorbing one type of acidic gas, or it may be capable of adsorbing two or more types of acidic gases.

[0018] The acid gas adsorbent contains an adsorbent compound capable of adsorbing acid gases. The acid gas adsorbent may consist solely of the adsorbent compound, or it may contain a carrier in addition to the adsorbent compound.

[0019] The adsorbent compound is arbitrarily and appropriately selected depending on the acidic gas. Examples of adsorbent compounds include organic compounds, inorganic compounds, and organic-inorganic composite compounds.

[0020] Examples of organic compounds include nitrogen-containing compounds, ionic liquids, and deep eutectic solvents. Examples of nitrogen-containing compounds include primary amines such as monoethanolamine and polyvinylamine; secondary amines such as diethanolamine, cyclic amines, and N-(3-aminopropyl)diethanolamine; tertiary amines such as methyldiethylamine and triethanolamine; ethyleneamine compounds such as tetraethylenepentamine; aminosilane coupling agents such as aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, and polyethyleneimine-trimethoxysilane; organic polymers having primary to tertiary amino groups; organic monomers having primary to tertiary amino groups; piperazine compounds such as 1-(2-hydroxyethyl)piperazine; and organic / inorganic compounds to which amino groups are added as substituents.

[0021] Ionic liquids are "salts" of liquids composed solely of ions (anions and cations). Examples of cations in ionic liquids include ammonium salts such as imidazolium salts and pyridinium salts; phosphonium ions; sulfonium salts; and inorganic ions. Examples of anions in ionic liquids include halogenated ions such as bromide ions and triflates; boron ions such as tetraphenylborates; phosphorus ions such as hexafluorophosphates; and sulfur ions such as alkyl sulfonates.

[0022] Examples of deep eutectic solvents include carboxylic acid-containing organic compounds such as decanoic acid, ester-containing organic compounds such as phenyl salicylate, alcohols such as decanol, phenols such as thymol, and ketone-containing organic compounds such as camphor, as hydrogen bond donors (HBDs); and ammonium salts having halogens or hydroxyanions such as tetra-n-octylammonium bromide, amine compound salts having halogens or hydroxyanions such as triethylenetetramine chloride, carboxylic acid-containing organic compounds such as lauric acid, alcohols such as menthol, and phenols such as thymol as hydrogen bond acceptors (HBAs).

[0023] Examples of inorganic compounds include metal hydroxides, metal carbonates, metal bicarbonates, metal oxides, and layered inorganic compounds. Examples of metal hydroxides include sodium hydroxide and potassium hydroxide. Examples of metal carbonates include potassium carbonate and calcium carbonate. Examples of metal bicarbonates include potassium bicarbonate and calcium bicarbonate. Examples of metal oxides include cerium oxide and zinc oxide. Examples of layered inorganic compounds include sodium ferrite and layered double hydroxides.

[0024] Examples of organic-inorganic composite compounds include organometallic structures (MOFs) such as MOF-74, MOF-200, and MOF-210.

[0025] These adsorbent compounds can be used individually or in combination. In one embodiment, the acid gas adsorbent contains the inorganic compounds described above. When the acid gas adsorbent contains inorganic compounds, the oxidation resistance of the acid gas adsorbent can be improved, and the performance of the acid gas adsorbent can be maintained over a long period of time. Among the inorganic compounds, metal carbonates are preferred, alkali metal carbonates are preferred, and potassium carbonate is even more preferred. When the acid gas adsorbent contains metal carbonates, the acid gas adsorbent can efficiently adsorb acid gases in the presence of moisture, and can smoothly desorb acid gases in the absence of moisture.

[0026] In one embodiment, the acidic gas adsorbent includes a carrier in addition to the adsorbent compound. The carrier has any suitable configuration capable of supporting the adsorbent compound. The carrier is preferably a porous carrier. If the carrier is porous, mesopores can be formed on the surface that can come into contact with the acidic gas. Examples of porous carriers include porous ceramic materials such as porous silica, porous alumina, and porous zirconia; organometallic structures (MOFs) such as MOF-74, MOF-200, and MOF-210; activated carbon; nitrogen-doped carbon; zeolites; carbon nanotubes; and polymers. The porous carrier can be used alone or in combination. Preferably, the porous carrier is made of a different material from the adsorbent compound. Among porous carriers, porous ceramic materials are more preferred.

[0027] The BET specific surface area of ​​a porous carrier is, for example, 50 m². ２ It is 1 / g or more, preferably 500m ２ It is 1 / g or more. On the other hand, the upper limit of the BET specific surface area of ​​porous carriers is typically 2000 m². ２ The value is / g. If the porous support has such a surface area, it can stably support the adsorbed compound, thereby improving the recovery efficiency of acidic gases.

[0028] Specific examples of acidic gas adsorbents containing an adsorbent compound and a carrier include potassium carbonate-containing silica, potassium carbonate-containing alumina, and potassium carbonate-containing activated carbon. When an acidic gas adsorbent contains an adsorbent compound and a carrier, the mass ratio of the adsorbent compound to the carrier (adsorbent compound / carrier) is, for example, 5 to 70, and preferably 10 to 50.

[0029] As shown in Figures 2 to 4, the acid gas concentrate 1 is configured to allow gas to pass through, and the acid gas adsorbent is positioned to be in contact with the gas passing through the acid gas concentrate 1. As shown in Figure 2, in one embodiment, the acid gas concentrate 1 includes a concentrate section 11. The concentrate section 11 has any suitable configuration. In the illustrated example, the concentrate section 11 has a honeycomb structure including a plurality of gas flow paths 114. The acid gas adsorbent is positioned to be in contact with the gas passing through at least a portion of the plurality of gas flow paths 114. With such a configuration, the pressure loss of the gas passing through the acid gas concentrate can be reduced, and energy savings can be achieved for the entire system.

[0030] The concentration unit 11 comprises a base material 111 and an adsorbent layer 116. In the illustrated example, the base material 111 has a honeycomb structure extending in a predetermined direction. The adsorbent layer 116 contains the above-mentioned acidic gas adsorbent and is arranged on the surface of the base material 111.

[0031] The base material 111 has any suitable shape (overall shape). Examples of the base material 111's shape include a cylindrical shape with a circular base, an elliptical prism shape with an elliptical base, a prismatic prism shape with a polygonal base, and a columnar shape with an irregular base. The base material 111 in the illustrated example has a prismatic shape. The outer diameter and length of the honeycomb-shaped base material are set appropriately according to the purpose.

[0032] In one embodiment, the substrate 111 includes partition walls 113 defining a plurality of cells 112. The cells 112 extend in the longitudinal direction (axial direction) of the substrate 111 from a first end face E1 (inlet end face) to a second end face E2 (outlet end face) (see Figure 3). The cells 112 have any suitable shape in a cross-section perpendicular to the longitudinal direction of the substrate 111. Examples of cell cross-sectional shapes include triangles, quadrilaterals, pentagons, polygons with hexagons or more, circles, and ellipses. The cross-sectional shapes and sizes of the cells may all be the same, or at least some may differ. Among such cell cross-sectional shapes, hexagons and quadrilaterals are preferred, and more preferably squares, rectangles, or hexagons.

[0033] The cell density in a cross-section perpendicular to the length direction of the honeycomb substrate (i.e., the number of cells 112 per unit area) is appropriately set depending on the purpose. The cell density is, for example, 4 cells / cm ２ to 320 cells / cm ２ . When the cell density falls within such a range, sufficient strength and effective GSA (geometric surface area) of the honeycomb substrate can be ensured.

[0034] The substrate 111 typically includes: an outer wall 115; and partition walls 113 positioned inside the outer wall 115. In the illustrated example, the outer wall 115 and the partition walls 113 are integrally formed. The outer wall 115 and the partition walls 113 may be separate members.

[0035] In the illustrated example, the outer wall 115 has a rectangular cylindrical shape. The thickness of the outer wall 115 can be set arbitrarily and appropriately. The thickness of the outer wall 115 is, for example, 0.1 mm to 10 mm.

[0036] The partition walls 113 define a plurality of cells 112. More specifically, the partition walls 113 include first partition walls 113a and second partition walls 113b orthogonal to each other, and the first partition walls 113a and the second partition walls 113b define the plurality of cells 112. The cross-sectional shape of the cells 112 is substantially square. Note that the configuration of the partition walls is not limited to the above-described partition walls 113. 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.

[0037] The thickness of the partition walls 113 is appropriately set according to the application of the acidic gas concentrator. The thickness of the partition walls 113 is typically thinner than the thickness of the outer wall 115. The thickness of the partition walls 113 is, for example, 0.03 mm to 0.6 mm. The thickness of the partition walls is measured, for example, by cross-sectional observation using a SEM (scanning electron microscope). When the thickness of the partition walls falls within such a range, the honeycomb substrate can have sufficient mechanical strength and a sufficient opening area (total area of cells in the cross-section).

[0038] The porosity of the partition walls 113 is appropriately set according to the purpose. The porosity of the partition walls 113 is, for example, 15% to 70%, preferably 20% to 45%. The porosity is measured by, for example, mercury porosimetry. The bulk density of the partition walls 113 is appropriately set according to the purpose. The bulk density of the partition walls 113 is, for example, 0.10 g / cm ３ to 0.60 g / cm ３ , preferably 0.20 g / cm ３ to 0.50 g / cm ３ . The bulk density is measured by, for example, mercury porosimetry.

[0039] As a material for forming the partition walls 113, ceramics is typically mentioned. Examples of the 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 may be used alone or in combination. Among the materials for forming the partition walls, preferred are cordierite, alumina, mullite, silicon carbide, silicon-silicon carbide composite materials, and silicon nitride, and more preferred are silicon carbide and silicon-silicon carbide composite materials.

[0040] In one embodiment, the adsorbent layer 116 is formed on the surfaces of the partition walls 113 in the cells 112. In the substrate 111, a gas flow path 114 is formed in a portion (typically a central portion) of the cross-section of the cell 112 where the adsorbent layer 116 is not formed. The adsorbent layer 116 may be formed on the entire inner surface of the partition wall 113 (that is, so as to surround the gas flow path 114) as shown in the illustrated example, or may be formed on a part of the surface of the partition wall. When the adsorbent layer is formed on the entire inner surface of the partition wall, the recovery efficiency of acid gas (typically CO ２ ) can be improved.

[0041] The gas flow path 114 extends from the first end face E1 (inlet end face) to the second end face E2 (outlet end face), similar to the cell 112. The cross-sectional shape of the gas flow path 114 is similar to that of the cell 112 described above, preferably a hexagon or quadrilateral, and more preferably a square, rectangle or hexagon. The cross-sectional shape and size of the gas flow path 114 may all be the same, or at least some may differ. Typically, the cell 112 (more specifically the gas flow path 114) is supplied with a gas to be treated, including an acidic gas, in the adsorption process, and the desorbed gas (circulating gas) flows through it in the desorption process.

[0042] The thickness of the adsorbent layer 116 is, for example, 5 μm to 100 μm, preferably 100 μm to 500 μm. The adsorbent layer 116 may consist only of an acidic gas adsorbent, or it may contain other components in addition to the acidic gas adsorbent. Examples of other components include organic binders and inorganic binders. The content ratio of the acidic gas adsorbent in the adsorbent layer 116 is, for example, 30% to 100% by mass, preferably 50% to 80% by mass.

[0043] The structure of the acid gas adsorption section is not limited to the embodiments described above. In another embodiment, the substrate 111 includes a partition wall 113 made of an acid gas adsorbent. In this case, the acid gas concentrator 1 does not need to include an adsorbent layer 116. With such a configuration, the amount of acid gas adsorbent per unit volume can be increased, and the adsorption efficiency of acid gases can be improved.

[0044] As shown in Figure 4, in yet another embodiment, the concentration unit 11 includes a plurality of adsorbent containment units 117.

[0045] Each of the multiple adsorbent storage sections 117 has a substantially plate shape. The multiple adsorbent storage sections 117 are stacked with spacing between them in the thickness direction. A gas flow path 114 is formed between adjacent adsorbent storage sections 117. In the illustrated example, five adsorbent storage sections 117 are arranged in parallel, but the number of adsorbent storage sections 117 is not limited to this. The number of adsorbent storage sections 117 is, for example, five or more, preferably ten or more, and more preferably twenty or more. The spacing between adjacent adsorbent storage sections 117 is, for example, 0.5 cm to 1.5 cm.

[0046] Each of the multiple adsorbent housing sections 117 comprises multiple pellet-shaped adsorbent materials 117a and a flexible fiber member 117b.

[0047] The pelletized adsorbent 117a functions as the acidic gas adsorbent described above. Examples of materials for the pelletized adsorbent 117a include activated carbon impregnated with the inorganic compound described above. The average primary particle size of the pelletized adsorbent 117a is, for example, 60 μm to 1200 μm. The filling ratio of the pelletized adsorbent 117a in the adsorbent containment section 117 can be any appropriate value.

[0048] The flexible fiber member 117b is typically formed in a hollow shape (bag shape) capable of accommodating a plurality of pellet-shaped adsorbents 117a. The flexible fiber member 117b allows the passage of gas and restricts the passage of pellet-shaped adsorbents. The flexible fiber member 117b may be a woven fabric or a nonwoven fabric. Examples of materials for the flexible fiber member 117b include organic fibers and natural fibers, and preferably polyethylene terephthalate fibers, polyethylene fibers, and cellulose fibers. The thickness of the flexible fiber member 117b is, for example, 25 μm to 500 μm.

[0049] The concentrated section 11 in the illustrated example further comprises a plurality of spacers 118. The spacers 118 are sandwiched between adjacent adsorbent storage sections 117. This ensures a stable spacing between adjacent adsorbent layers. In one embodiment, the plurality of adsorbent storage sections 117 and the plurality of spacers 118 are arranged in a roughly zigzag shape when viewed from a direction perpendicular to the thickness direction of the adsorbent storage section 117 (the depth direction of the paper in Figure 4).

[0050] Examples of such a concentration unit 11 include the gas separation unit described in International Publication No. 2014 / 170184. The entire description of this publication is incorporated herein by reference.

[0051] B-1-2. Housing As shown in Figure 5, in one embodiment, the acid gas concentrator 1 further comprises a housing 12. The housing 12 houses the concentrator 11. In the illustrated example, the housing 12 has a cylindrical shape extending in a predetermined direction.

[0052] In one embodiment, the housing 12 has a first inlet 121, a first outlet 122, a second inlet 123, and a second outlet 124. The first inlet 121 is located at one end of the housing 12. The first outlet 122 is located at the end of the housing 12 opposite to the first inlet 121 (the other end). The second inlet 123 is located in the longitudinal direction of the housing 12 between the first inlet 121 and the first outlet 122. The second inlet 123 is typically provided on the side wall of the housing 12. The second outlet 124 is located in the longitudinal direction of the housing 12 between the first inlet 121 and the first outlet 122. In the illustrated example, the second outlet 124 is located between the second inlet 123 and the first outlet 122. The second outlet 124 is typically provided on the side wall of the housing 12. With this configuration, the opening areas of the first inlet, first outlet, second inlet, and second outlet can be appropriately designed according to the flow rate of the corresponding process. As a result, the adsorption process and desorption process, described later, can be carried out efficiently.

[0053] B-1-3. First and Second Valves In the illustrated example, the acid gas concentrator 1 further comprises a first valve 13 and a second valve 14. Each of the first valve 13 and the second valve 14 can open and close the internal space of the housing 12. The first valve 13 is located between the first inlet 121 of the housing 12 and the concentrator 11. The second valve 14 is located on the opposite side of the concentrator 11 from the first valve 13. The second valve 14 is also located between the concentrator 11 and the first outlet 122 of the housing 12. When the first valve 13 and the second valve 14 are closed, they partition the internal space of the housing 12, defining the containment space S in which the concentrator 11 is located. The second inlet 123 and the second outlet 124 are located between the first valve 13 and the second valve 14. With this configuration, by closing the first and second valves and performing the desorption process described later, the temperature inside the containment space where the concentration unit is housed can be appropriately adjusted, and the recovery efficiency of acidic gas can be more stably improved.

[0054] Examples of the first valve 13 include a ball valve, a gate valve, and a butterfly valve. The first valve 13 is preferably a butterfly valve. The second valve 14 is described in the same manner as the first valve 13.

[0055] B-2. Gas to be treated supply unit As shown in Figure 1, in one embodiment, the gas to be treated supply unit 2 is configured to supply the gas to be treated to the housing 12 (see Figure 5) which houses the concentration unit 11. In the illustrated example, the gas to be treated supply unit 2 can supply the gas to be treated to the first inlet 121 (see Figure 5) of the housing 12. The gas to be treated will be described in detail later.

[0056] In one embodiment, the gas to be treated supply unit 2 includes a supply line 21. The supply line 21 is typically a pipe through which the gas to be treated can pass. The upstream end of the supply line 21 in the direction of passage of the gas to be treated may be connected to a gas supply source (not shown) for the gas to be treated. The downstream end of the supply line 21 in the direction of passage of the gas to be treated is connected to the housing 12 so as to be connected to a first inlet 121 (see Figure 5).

[0057] The gas to be treated supply unit 2 may optionally include a moisture content adjustment unit (not shown) and / or a blower (not shown). The moisture content adjustment unit is configured to adjust the moisture content in the gas to be treated. Examples of the moisture content adjustment unit include any suitable humidifier. The blower is configured to adjust the flow rate of the gas to be treated. Examples of the blower include any suitable blower.

[0058] B-3. ​​Air Supply Unit In one embodiment, the air supply unit 3 is configured to supply air as a desorbed gas to the housing 12 (see Figure 5) that houses the concentration unit 11. In the illustrated example, the air supply unit 3 is capable of supplying air to the second inlet 123 (see Figure 5) of the housing 12.

[0059] In one embodiment, the air supply unit 3 comprises an air supply line 31 and a heating unit 32. The air supply line 31 is typically a pipe through which air can pass. The downstream end of the air supply line 31 in the direction of air passage is connected to the side wall of the housing 12 so as to communicate with the second inlet 123 (see Figure 5). The heating unit 32 is configured to heat the air supplied to the acid gas concentrater 1. This allows the acid gas adsorbent contained in the acid gas concentrater to be heated more efficiently, and the acid gas to be desorbed from the acid gas adsorbent with less energy. In the illustrated example, the heating unit 32 is provided in the air supply line 31. The heating unit 32 is configured to heat the gas passing through the air supply line 31. The heating unit 32 has any suitable configuration. Examples of the heating unit 32 include a heater, a steam heat exchanger (STM), and a heat exchanger using a heat transfer medium.

[0060] B-4. Return Section In one embodiment, the return section 4 is configured to return the gas (hereinafter sometimes referred to as circulating gas) that has passed through the concentration section 11 and been discharged from the housing 12 to the acid gas concentration device 1. The circulating gas typically contains desorbed gas (air) and acid gas. In the illustrated example, the return section 4 is configured to return the circulating gas discharged from the second outlet 124 of the housing 12 (see Figure 5) to the air supply section 3. As a result, the circulating gas is returned to the acid gas concentration device via the desorbed gas supply section.

[0061] In one embodiment, the return section 4 includes a return line 41 and an on-off valve 42. The return line 41 is typically a pipe through which circulating gas can pass. The upstream end of the return line 41 in the direction of circulating gas passage is connected to the side wall of the housing 12 so as to connect to the second outlet 124 (see Figure 5). The downstream end of the return line 41 in the direction of circulating gas passage is connected to the air supply line 31 (more specifically, the portion of the air supply line 31 upstream of the heating section 32). The on-off valve 42 is provided on the return line 41 and can open and close the return line 41. Examples of the on-off valve 42 include a ball valve, a gate valve, and a butterfly valve.

[0062] In the illustrated example, when the first valve 13 and the second valve 14 (see Figure 5) are closed and the on / off valve 42 is open, the housing 12, the return line 41, and the air supply line 31 form a closed line. This allows the circulating gas to circulate smoothly through the closed line during the desorption process described later.

[0063] Furthermore, the return unit 4 may also include a dehumidification unit 43. The dehumidification unit 43 is configured to remove moisture contained in the desorbed gas (air) returned by the return unit 4. More specifically, the dehumidification unit 43 is configured to remove moisture contained in the circulating gas. With such a configuration, even if the acidic gas adsorbent contains an inorganic compound and the return unit returns the desorbed gas (air), it is possible to suppress the re-adsorption of acidic gas onto the acidic gas adsorbent. In the illustrated example, the dehumidification unit 43 is provided in the return line 41. The dehumidification unit 43 has any suitable configuration. Examples of moisture removal methods that the dehumidification unit 43 can perform include the TSA method (Temperature Swing Absorption), the PSA method (Pressure Swing Absorption), the MSA method (Moisture Swing Absorption), the ESA method (Electric Swing Absorption), and membrane separation methods.

[0064] B-5. Concentrated Gas Supply Unit In one embodiment, the concentrated gas supply unit 5 is configured to supply the concentrated gas discharged from the housing 12 after passing through the concentration unit 11 to the acid gas recovery device 6 or the acid gas utilization equipment 7. Typically, the concentrated gas supply unit 5 directly supplies the concentrated gas to the acid gas recovery device 6 or the acid gas utilization equipment 7 without storing the concentrated gas in other components (e.g., tanks). In the illustrated example, the concentrated gas supply unit 5 includes a concentrated gas supply line 51. Typically, the concentrated gas supply line 51 is a pipe through which the concentrated gas can pass. The upstream end of the concentrated gas supply line 51 in the direction of concentrated gas passage is connected to the housing 12 so as to be connected to the first outlet 122 (see Figure 5). The downstream end of the concentrated gas supply line 51 in the direction of concentrated gas passage is connected to the acid gas recovery device 6 or the acid gas utilization equipment 7.

[0065] B-6. Acid Gas Recovery Device In one embodiment, the acid gas recovery device 6 is configured to adsorb or separate acid gases. More specifically, the acid gas recovery device 6 is configured to adsorb or separate acid gases from the concentrated gas supplied from the concentrated gas supply unit 5. Examples of the acid gas recovery device 6 include an amine absorption tower, a PSA (Pressure Swing Absorption) type gas separation device, and a membrane separation device.

[0066] B-7. Acid Gas Utilization Equipment In one embodiment, the acid gas utilization equipment 7 is configured to utilize acid gas for promoting the growth of crops or cultivating algae. More specifically, the acid gas utilization equipment 7 is configured to utilize concentrated gas supplied from the concentrated gas supply unit 5 for promoting the growth of crops or cultivating algae. Examples of the acid gas utilization equipment 7 include algae aeration devices, greenhouses for growing crops, plant factories, and open-field cultivation facilities.

[0067] C. Operating Method of the Acid Gas System Next, an operating method of the acid gas system according to one embodiment will be described. In one embodiment, the operating method of the acid gas system includes a concentration step, a concentrated gas supply step, and a recovery step or utilization step. The concentration step and the concentrated gas supply step are preferably carried out continuously.

[0068] C-1. Concentration Process In the concentration process, the gas to be treated is supplied to the acid gas concentrater 1, and the concentrated gas is discharged from the acid gas concentrater 1. In one embodiment, the concentration process includes an adsorption process and a desorption process. The concentration process may further include a water removal process after the adsorption process and before the desorption process.

[0069] C-1-1. Adsorption Process As shown in Figure 5, in the adsorption process, the gas to be treated is supplied to the concentration section 11 of the acid gas concentration device 1. In the illustrated example, the first valve 13 and the second valve 14 are in the open state, and the gas to be treated is supplied to the concentration section 11 via the first inlet 121.

[0070] The gas to be treated contains acidic gases at the concentrations mentioned above. Typical examples of the gas to be treated are CO2. ２ CO２ It is a contained gas. CO ２ The contained gas is CO ２ In addition, nitrogen may be included. In one embodiment, the gas to be treated (CO ２ The contained gases are air (atmosphere) and / or exhaust gases from factories, power plants, incineration facilities, etc.

[0071] The gas to be treated preferably contains water vapor in addition to the acidic gas. The dew point temperature of the water vapor in the gas to be treated at atmospheric pressure is, for example, -20°C or higher, and preferably 2°C or higher. On the other hand, the upper limit of the dew point temperature of the water vapor in the gas to be treated is typically 80°C. When the gas to be treated contains water vapor in this way, the acidic gas can be stably adsorbed onto the acidic gas adsorbent if the acidic gas adsorbent contains an inorganic compound.

[0072] Subsequently, as the gas to be treated passes through the concentration unit 11, the acidic gases contained in the gas to be treated (typically CO) ２ The gas comes into contact with the acid gas adsorbent, and the acid gas adsorbent adsorbs the acid gas. The treated gas, with its reduced acid gas concentration, passes through the concentration unit 11 and is discharged from the first outlet 122 (see Figure 5) of the housing 12.

[0073] The temperature inside the acid gas concentrater during the adsorption process (adsorption temperature) is, for example, 0°C to 80°C, preferably 10°C to 50°C. In one embodiment, the adsorption temperature is the same as the ambient temperature. Typically, the adsorption temperature is the temperature of the concentrate in the adsorption process. The duration of the adsorption process (adsorption time) is, for example, 10 minutes to 10 hours, preferably 15 minutes to 6 hours. When the adsorption temperature and / or adsorption time are within the above range, the acid gas adsorbent can stably adsorb the acid gas.

[0074] The acid gas adsorption rate in the adsorption process (= 100 - (acid gas concentration in the treated gas / acid gas concentration in the treated gas × 100)) is, for example, 60% or more, preferably 75% or more, more preferably 80% or more, and particularly preferably 90% or more. On the other hand, the upper limit of the acid gas adsorption rate in the adsorption process is typically 100%.

[0075] C-1-2. Moisture Removal Process In the moisture removal process, the air used as the desorption gas is preheated by any appropriate method to remove moisture from the air.

[0076] In the moisture removal process, the heating temperature of the air typically exceeds the adsorption temperature described above. The heating temperature of the air is, for example, 60°C or higher, preferably 80°C or higher. On the other hand, the heating temperature of the air is, for example, 200°C or lower, preferably 120°C or lower. When the air is heated in this way, moisture can be stably removed from the air.

[0077] The air used in the desorption process is substantially free of water vapor. In the air used in the desorption process, the dew point temperature of water vapor at atmospheric pressure is, for example, 50°C or lower, preferably 30°C or lower. On the other hand, in the air used in the desorption process, the lower limit of the dew point temperature of water vapor at atmospheric pressure is typically -80°C. When the dew point temperature of water vapor at atmospheric pressure is within this range, even if the acidic gas adsorbent contains inorganic compounds, the re-adsorption of acidic gas onto the acidic gas adsorbent during the desorption process can be stably suppressed.

[0078] C-1-3. Desorption Process In the desorption process, air as the desorption gas (preferably the air prepared in the moisture removal process described above) is supplied to the concentration section 11 of the acid gas concentration device 1. More specifically, as shown in Figure 5, with the supply of the gas to be processed to the concentration section 11 stopped, air whose temperature and / or moisture content has been adjusted to the above-described range is supplied from the air supply section 3 to the concentration section 11. In the illustrated example, the first valve 13 and the second valve 14 are closed, and the on / off valve 42 (see Figure 1) is open, and air as the desorption gas is supplied from the air supply section 3 to the housing space S of the housing 12 via the second inlet 123. The pressure of the air supplied to the concentration section is, for example, 0.01 MPa (absolute pressure) to 1 MPa (absolute pressure), and preferably 0.05 MPa (absolute pressure) to 0.2 MPa (absolute pressure).

[0079] As a result, air is supplied to the acid gas concentrate 1, and the temperature inside the acid gas concentrate 1 is raised from the adsorption temperature to the desorption temperature. More specifically, the concentration section 11 is raised from the adsorption temperature to the desorption temperature. The range of the desorption temperature is, for example, the same as the range of heating temperatures for the desorbed gas in the moisture removal process described above. At this time, as the temperature of the acid gas adsorbent rises, the acid gas adsorbed on the acid gas adsorbent is desorbed from the acid gas adsorbent over time. The acid gas desorbed from the acid gas adsorbent is discharged from the acid gas concentrate 1 together with the desorbed gas (air). Therefore, the circulating gas containing the acid gas and the desorbed gas (air) is discharged from the housing 12 via the second outlet 124.

[0080] Subsequently, as shown in Figure 1, at least a portion of the circulating gas is returned to the air supply unit 3 by the return unit 4, and then supplied again from the air supply unit 3 to the acid gas concentrater 1. In the illustrated example, the circulating gas circulates through the closed line described above. This allows for efficient utilization of the thermal energy of the air as the desorbed gas to raise the temperature of the acid gas adsorbent.

[0081] At this time, the dehumidification unit 43 removes moisture contained in the circulating gas as needed. This allows for a suitable adjustment of the moisture content (water vapor content) in the circulating gas, even if moisture is generated when the acidic gas desorbs from the acidic gas adsorbent. Therefore, when the acidic gas adsorbent contains an inorganic compound, the acidic gas can be smoothly desorbed from the acidic gas adsorbent, and the re-adsorption of the acidic gas onto the acidic gas adsorbent can be stably suppressed. The dew point temperature of water vapor in the circulating gas at atmospheric pressure is, for example, 50°C or lower, preferably 30°C or lower. On the other hand, the lower limit of the dew point temperature of water vapor in the circulating gas at atmospheric pressure is typically -80°C.

[0082] Furthermore, the heating unit 32 may adjust the temperature of the circulating gas. This allows the temperature of the circulating gas to be suitably adjusted even if the temperature of the acidic gas adsorbent decreases when the acidic gas is released from the adsorbent.

[0083] The duration of the desorption process (desorption time) is appropriately changed according to the desorption temperature. The desorption time is, for example, 5 to 120 minutes, preferably 15 to 60 minutes. When the desorption time is within this range, the deterioration and volatilization of the acidic gas adsorbent can be suppressed.

[0084] C-2. Concentrated Gas Supply Process In one embodiment, in the concentrated gas supply process, the circulating gas that has been circulated through the acid gas concentrater 1 in the desorption process is supplied as concentrated gas to the acid gas recovery device 6 or the acid gas utilization equipment 7. More specifically, the concentrated gas (circulating gas) is supplied from the acid gas concentrater 1 to the acid gas recovery device 6 or the acid gas utilization equipment 7 by the concentrated gas supply unit 5. In the illustrated example, the first valve 13 (see Figure 5) is closed, the on-off valve 42 is closed, and the second valve 14 (see Figure 5) is open. Subsequently, the concentrated gas (circulating gas) that has been circulating in the closed line is supplied to the acid gas recovery device 6 or the acid gas utilization equipment 7 via the concentrated gas supply line 51. The concentrated gas contains acid gas at the concentration described above. In addition to acid gas, the concentrated gas may also contain other gas components.

[0085] C-3. Recovery Process and Utilization Process When concentrated gas is supplied to the acid gas recovery device 6, the acid gas recovery device 6 recovers the acid gas from the concentrated gas as needed and appropriately (recovery process). Also, when concentrated gas is supplied to the acid gas utilization equipment 7, the concentrated gas is utilized as needed and appropriately in the acid gas utilization equipment 7 (utilization process).

[0086] C-4. Cooling Process In the acid gas concentrate 1, a cooling process may be performed after the desorption process. As shown in Figure 5, in the cooling process according to one embodiment, a cooling gas is supplied to the acid gas concentrate 1 to cool the temperature inside the acid gas concentrate 1 from the desorption temperature to the adsorption temperature. More specifically, the temperature of the concentrate 11 is cooled from the desorption temperature to the adsorption temperature. In the illustrated example, the first valve 13 and the second valve 14 are in the open state, and the cooling gas is supplied to the concentrate 11 through the first inlet 121 of the housing 12.

[0087] As a cooling gas, for example, CO ２Examples include gases, nitrogen gas, oxygen gas, and air. The cooling gas can be used alone or in combination. The temperature range of the cooling gas is, for example, the same as the adsorption temperature range described above. The pressure of the cooling gas is typically atmospheric pressure (0.1 MPa). When the acid gas adsorbent contains the inorganic compounds described above, air can be suitably used as the cooling gas because the acid gas adsorbent has excellent oxidation resistance. Using air as the cooling gas allows for smooth cooling of the concentration section. Therefore, the cooling process time (cooling time) can be shortened, and as a result, the amount of acid gas recovered per unit time can be improved. The cooling time is, for example, 5% to 60%, preferably 10% to 40%, when the sum of the adsorption time and desorption time is taken as 100%. The cooling time is, for example, 1 minute to 120 minutes, preferably 5 minutes to 30 minutes.

[0088] Subsequently, once the concentration unit 11 has cooled to the adsorption temperature, the adsorption process described above is typically restarted.

[0089] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0090] <<Examples 1-4>> The energy required to recover acidic gas (desorption energy) in the acidic gas system shown in Figure 1 was calculated using computer simulation. The acidic gas system model used in the simulation included an acidic gas concentrator equipped with a concentration section as shown in Figure 2, and an amine absorption tower as an acidic gas recovery device. In the acidic gas system model, alkali metal carbonate was used as the acidic gas adsorbent, the partition wall thickness was set to 0.4 mm, and the cell density was set to 100 cells / cm². ２ The porosity of the partition wall was set to 30%. In addition, in the acidic gas system model, the amine absorption tower had the configuration described in the following literature, and a 30 wt% aqueous solution of MEA (monoethanolamine) was set as the amine-based chemical adsorbent. Literature: Hailong Li et al., "Technologies for increasing CO ２Concentration in exhaust gas from natural gas-fired power production with post-combustion, amine-based CO ２ energy 36 (2011) 1124-1133

[0091] Next, the energy required for the concentration process carried out in the acid gas concentrate (amount of desorption energy in the acid gas concentrate) was calculated. More specifically, a simulation was conducted in which a target gas having the acid gas concentration shown in Table 1 was supplied to the concentration section, the acid gas was adsorbed onto an acid gas adsorbent (adsorption process), the concentration section was heated to 180°C to desorb the acid gas from the acid gas adsorbent, and the concentrated gas having the acid gas concentration shown in Table 1 was discharged. Subsequently, the amount of desorption energy in the acid gas concentrate was calculated from the heat capacity of the desorption process in which the concentration section was heated to 180°C in the simulation, the reaction heat required for the desorption of the acid gas in the simulation, and the measurement results when alkali metal carbonate was used as the acid gas adsorbent. The concentration rate and desorption energy of the acid gas in the acid gas concentrate are shown in Table 1.

[0092] Next, the energy required for the recovery process carried out in the amine absorption tower to which the concentrated gas is supplied (the amount of desorption energy in the acid gas recovery device) was calculated. More specifically, a simulation was performed in which concentrated gas with the acid gas concentrations shown in Table 1 was supplied to the amine absorption tower, and the amount of desorption energy in the acid gas recovery device was calculated based on the physical properties described in the aforementioned paper. Table 1 shows the amount of desorption energy in the acid gas recovery device and the sum of the amount of desorption energy in the acid gas system.

[0093] <<Comparative Examples 1-4>> In an acidic gas system having the same configuration as Examples 1-4 except that it does not have an acidic gas concentration device, the energy required to recover the acidic gas (desorption energy) was calculated using computer simulation. In other words, the simulation was performed when the target gas to be treated, having the acidic gas concentrations shown in Table 1, was directly supplied to the amine absorption tower. Table 1 shows the sum of the desorption energy in the acidic gas recovery device and the desorption energy in the acidic gas system.

[0094]

[0095] <Evaluation> As is clear from Table 1, the acid gas system is equipped with an acid gas concentrate, and the acid gas concentrate is configured to discharge a concentrated gas with a higher concentration of acid gas than the gas to be treated that was supplied to it. When this concentrated gas is supplied to the acid gas recovery device, it can be seen that energy savings can be achieved in the acid gas recovery device. In particular, it can be seen that if the concentration ratio (acid gas concentration in concentrated gas / acid gas concentration in gas to be treated) is 2.5 times, energy savings can be achieved for the acid gas system as a whole.

[0096] The acidic gas system according to the embodiment of the present invention can be used for the separation and recovery of acidic gases, and is particularly suitable for use in the carbon dioxide capture, utilization, and storage (CCUS) cycle.

[0097] 1 Acid Gas Concentrator 11 Concentration Section 114 Gas Flow 2 Treatment Gas Supply Section 3 Air Supply Section 4 Return Section 5 Concentrated Gas Supply Section 6 Acid Gas Recovery Device 7 Acid Gas Utilization Equipment 100 Acid Gas System

Claims

1. An acid gas system comprising an acid gas recovery device for recovering acid gases or an acid gas utilization facility for utilizing acid gases, the system comprising: an acid gas concentrate that is supplied with a gas to be treated containing acid gases and is configured to discharge a concentrated gas having a higher concentration of acid gases than the gas to be treated; a gas to be treated supply unit configured to supply the gas to be treated having an acid gas concentration of 10% by volume or less to the acid gas concentrate; and a concentrated gas supply unit configured to supply the concentrated gas from the acid gas concentrate to the acid gas recovery device or the acid gas utilization facility, wherein the acid gas concentrate is configured such that the acid gas concentration in the concentrated gas is 2.5 times or more the acid gas concentration in the gas to be treated.

2. The acid gas system according to claim 1, wherein the acid gas concentration device includes an acid gas adsorbent capable of adsorbing acid gases, and the acid gas adsorbent capable of desorbing adsorbed acid gases when heated to a predetermined temperature or higher.

3. The acid gas system according to claim 2, further comprising an air supply unit configured to supply air at a predetermined temperature or higher to the acid gas concentrator as a desorption gas for heating the acid gas adsorbent.

4. The acid gas system according to claim 3, further comprising a return unit configured to return at least a portion of the desorbed gas that has passed through the acid gas concentrater to the acid gas concentrater.

5. The acid gas concentration system according to claim 2, wherein the acid gas concentration device comprises a concentration section having a honeycomb structure including a plurality of gas flow paths, and the acid gas adsorbent is arranged to be in contact with the gas passing through at least a portion of the plurality of gas flow paths.

6. The acid gas system according to claim 2, wherein the acid gas adsorbent comprises an inorganic compound.

7. The acid gas system according to any one of claims 1 to 6, wherein the acid gas includes carbon dioxide gas.

8. The acid gas system according to any one of claims 1 to 6, comprising an acid gas recovery device configured to adsorb or separate the acid gas.

9. The acid gas system according to any one of claims 1 to 6, comprising the acid gas utilization equipment configured to utilize the acid gas for promoting the growth of crops or cultivating algae.

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