Acid gas absorbent, acid gas removal method, and acid gas removal apparatus

Abstract

The present invention provides an acidic gas absorbent that absorbs a large amount of carbon dioxide, efficiently separates and recovers it, and has low emission compared to other amines, as well as an acidic gas removal device and acidic gas removal method using the same. [Solution] The acidic gas absorbent of the embodiment comprises a heterocyclic amine compound represented by the following formula (1) and a low molecular weight polyol compound. JPEG2026084925000006.jpg2787 [In the formula, R 1 Each of these independently represents a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group or aminoalkyl group having 1 to 6 carbon atoms, R 2 R represents a hydroxyalkyl group or aminoalkyl group having 2 to 6 carbon atoms. 1 and R 2 At least one of them contains a hydroxyalkyl group or an aminoalkyl group.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to an acidic gas absorbent, and an acidic gas removal device and acidic gas removal method using the same. [Background technology]

[0002] In recent years, the greenhouse effect caused by rising carbon dioxide (CO2) concentrations has been pointed out as one of the causes of global warming, making international measures to protect the environment on a global scale an urgent necessity. Industrial activities are a major source of CO2 emissions, and there is growing momentum to reduce these emissions.

[0003] Technologies to suppress the rise in concentration of acidic gases, including CO2, include the development of energy-saving products, technologies for separating and recovering emitted acidic gases, technologies for utilizing acidic gases as a resource or for sequestering and storing them, and the transition to alternative energy sources such as renewable energy and nuclear energy that do not emit acidic gases.

[0004] To date, acid gas separation technologies have been studied, including absorption, adsorption, membrane separation, and cryogenic methods. Among these, the absorption method is suitable for processing large quantities of gas, and its application to factories and power plants is being considered.

[0005] Therefore, methods are being implemented worldwide for facilities such as thermal power plants that use fossil fuels, in which exhaust gases generated when fossil fuels (coal, oil, natural gas, etc.) are burned are brought into contact with chemical absorbents to remove and recover CO2 from the combustion exhaust gas, and methods for storing the recovered CO2 are also being implemented. In addition, it has been proposed to use chemical absorbents to remove acidic gases other than CO2, such as hydrogen sulfide (H2S).

[0006] Generally, alkanolamines, such as monoethanolamine (MEA), have been developed as chemical absorbents used in absorption methods since around the 1930s and are still in use today. This method is economical and allows for easy scaling up of the removal equipment.

[0007] Existing, widely used alkanolamines include monoethanolamine, methyldiethanolamine, and diethanolamine. In particular, secondary amines such as methylethanolamine and ethylethanolamine have been widely used due to their rapid reaction rates. However, these compounds have drawbacks, including high energy requirements for regeneration, corrosiveness, and susceptibility to degradation. On the other hand, methyldiethanolamine has low corrosiveness and low energy requirements for regeneration, but suffers from a low absorption rate. Therefore, new absorbents are being developed to address these issues.

[0008] Now, among amine compounds, there is a great deal of research being conducted on alkanolamines, which have structural steric hindrance, as absorbents for acidic gases. Sterically hindrance alkanolamines such as 2-isopropylaminoethanol are known to have the advantage of absorbing acidic gases as bicarbonates, resulting in high absorption rates and low energy requirements for regeneration. The reaction rate of sterically hindered amine compounds depends on the degree of reaction hindrance determined by their stereostructure. While the reaction rates of sterically hindered amine compounds are lower than those of secondary amines such as methylethanolamine and ethanolamine, they are higher than those of tertiary amines.

[0009] Furthermore, although their absorption is inferior to that of absorption solutions containing the sterically hindered amine compounds mentioned above, absorption solutions with improved dissipation properties using amino acid salts have also been reported. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2008-307519 [Patent Document 2] Special Publication No. 2011-525422 [Patent Document 3] Japanese Patent Application Publication No. 5-301023

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, even with these technologies, the acidic gas absorption capacity and environmental aspects, such as the amount of acidic gas absorbed and the emission into the atmosphere, are still insufficient, and an absorption liquid that can solve these problems simultaneously is required.

[0012] The problems to be solved by the present invention are to provide an acidic gas absorbent that can sufficiently absorb carbon dioxide, efficiently separate and recover the absorbed carbon dioxide, and has low diffusibility of amine compounds, as well as an acidic gas removal device and an acidic gas removal method using the same.

Means for Solving the Problems

[0013] The acidic gas absorbent of the embodiment contains a heterocyclic amine compound represented by the following formula (1), a low molecular weight polyol compound selected from the group consisting of a low molecular weight diol compound and a low molecular weight triol compound, and water.

Chemical Formula

[0014] The acid gas removal method of the embodiment is to contact a gas containing an acid gas with the acid gas absorbent according to the above-described embodiment to remove the acid gas from the gas containing the acid gas.

[0015] The acid gas removal apparatus of the embodiment is an acid gas removal apparatus that contacts a gas containing an acid gas with an acid gas absorbent to remove the acid gas from the gas, regenerates the acid gas absorbent by removing the acid gas from the acid gas absorbent that has absorbed the acid gas, and reuses the acid gas absorbent regenerated in the regeneration tower in the absorption tower, and uses the acid gas absorbent according to the above-described embodiment.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram of the acid gas removal apparatus of the embodiment.

Mode for Carrying Out the Invention

[0017] Hereinafter, the embodiments will be described in detail. The acid gas absorbent according to the embodiment contains a heterocyclic amine compound represented by the following formula (1), a low molecular weight polyol compound, and water.

Chemical formula

[0018] The amine compound represented by the above formula (1) can be dissolved in a solvent such as water to obtain an acidic gas absorbent having a high acidic gas absorption capacity. In the following embodiments, the case where the acidic gas is carbon dioxide will be described as an example, but the acidic gas absorbent according to the embodiments of the present invention can obtain the same effects with respect to other acidic gases such as hydrogen sulfide.

[0019] Examples of the hydroxyalkyl group in the formula (1) include a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2,3-dihydroxypropyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, a 2-hydroxypentyl group, a 3-hydroxypentyl group, a 4-hydroxypentyl group, a 2-hydroxyhexyl group, a 3-hydroxyhexyl group, a 4-hydroxyhexyl group, a 5-hydroxyhexyl group, and the like. Among them, a 2-hydroxyethyl group or a 2-hydroxypropyl group is preferable as the hydroxyalkyl group.

[0020] Examples of the aminoalkyl group in the formula (1) include a 2-aminoethyl group, a 2-aminopropyl group, a 3-aminopropyl group, a 2-aminobutyl group, a 3-aminobutyl group, a 4-aminobutyl group, a 2-aminopentyl group, a 3-aminopentyl group, a 4-aminopentyl group, a 5-aminopentyl group, a 2-aminohexyl group, a 3-aminohexyl group, a 4-aminohexyl group, a 5-aminohexyl group, a 6-aminohexyl group, and the like. Among them, a 2-aminoethyl group is preferable as the aminoalkyl group.

[0021] R in the formula (1) 1 When it is an alkyl group, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and the like. From the viewpoint of the reactivity with carbon dioxide of the above formula (1), R 1 is preferably hydrogen, a methyl group, or an ethyl group, and more preferably hydrogen or a methyl group. Furthermore, R 1The alkyl group may contain heteroatoms such as Si, O, N, and S, and may also contain these heteroatoms, particularly oxygen atoms, as members of the cyclic structure.

[0022] Furthermore, the heterocyclic amine compound represented by formula (1) is R 1 and R 2 At least one of them contains a hydroxyalkyl group or an aminoalkyl group. Here, R 1 and R 2 Preferably, at least one of them contains a hydroxyalkyl group, and in particular R 2 It is preferable that it contains a hydroxyalkyl group.

[0023] Examples of heterocyclic amine compounds represented by formula (1) include the following: N-(2-hydroxyethyl)piperazine, N-(3-hydroxypropyl)piperazine, N-(2,3-dihydroxypropyl)piperazine, N-(4-hydroxybutyl)piperazine, N-(5-hydroxypentyl)piperazine, N-(6-hydroxyhexyl)piperazine, N-(2-hydroxypropyl)piperidine, N-(3-hydroxypropyl)piperidine, N-(2,3-dihydroxypropyl)piperidine, N-(4-hydroxybutyl)piperidine, N-(5-hydroxypentyl)piperazine, N-(6-hydroxyhexyl)piperidine, N-(2-aminoethyl)piperazine, N-(3-aminopropyl)piperazine, N-(2,3-diaminopropyl)piperazine, N-(4-aminobutyl)piperazine, N-(5-aminopentyl)piperazine, N-(6-aminohexyl)piperazine, N-(2-aminopropyl)piperidine, N-(3-aminopropyl)piperidine, N-(2,3-diaminopropyl)piperidine, N-(4-aminobutyl)piperidine, N-(5-aminopentyl)piperazine, and N-(6-aminohexyl)piperidine Of these, 1-(2-hydroxyethyl)piperazine or 1-(2-hydroxypropyl)piperazine is preferably used.

[0024] In the embodiments, one compound selected from the above group may be used as the heterocyclic amine compound, or a mixture of two or more compounds selected from the above group may be used.

[0025] In the embodiment, the content of the heterocyclic amine compound in the acidic gas absorbent is preferably 15 to 60% by mass, based on the total mass of the acidic gas absorbent. Generally, a higher amine compound content results in a greater absorption and desorption of carbon dioxide per unit volume, and a faster absorption and desorption rate of carbon dioxide, which is preferable in terms of energy consumption, plant equipment size, and processing efficiency.

[0026] However, if the content of the amine compound is too high, drawbacks such as the inability of water as an activator for carbon dioxide absorption to function adequately and an increase in the viscosity of the absorbent solution become significant. In the embodiment, when the content of the heterocyclic amine compound is 65% by mass or less, such a decrease in performance is not observed. Furthermore, by setting the content of the heterocyclic amine compound to 30% by mass or more, sufficient carbon dioxide absorption amount and absorption rate can be obtained, resulting in excellent processing efficiency.

[0027] In this embodiment, an acidic gas absorbent containing a heterocyclic amine compound in the range of 15 to 60% by mass is advantageous for carbon dioxide recovery because, when used for carbon dioxide recovery, it not only has a high carbon dioxide absorption amount and absorption rate, but also a high carbon dioxide desorption amount and desorption rate, thus enabling efficient carbon dioxide recovery. The heterocyclic amine compound content is more preferably 30 to 60% by mass.

[0028] The acidic gas absorbent according to the embodiment may also contain amine compounds other than the heterocyclic amine compound represented by formula (1), such as alkanolamines.

[0029] Examples of alkanolamines that can be used include Monoethanolamine, 2-amino-2-methylpropanolamine, 2-amino-2-methyl-1,3-dipropanolamine, Methylaminoethanol, Ethylaminoethanol, Propylaminoethanol, Diethanolamine, Bis(2-hydroxy-1-methylethyl)amine, Methyldiethanolamine, Dimethylethanolamine, Diethylethanolamine, Triethanolamine, Dimethylamino-1-methylethanol, 2-methylaminoethanol, 2-ethylaminoethanol, 2-Propylaminoethanol, n-butylaminoethanol, 2-(isopropylamino)ethanol, and 3-ethylaminopropanol, These are some examples.

[0030] The heterocyclic amine compound represented by formula (1) is a secondary amine compound, and generally, the nitrogen atom of the secondary amino group combines with carbon dioxide to form a carbamate ion, which contributes to improving the absorption rate in the initial stages of the reaction.

[0031] The acidic gas absorbent according to this embodiment includes a low molecular weight polyol compound. This low molecular weight polyol compound is selected from the group consisting of low molecular weight diol compounds and low molecular weight triol compounds. Here, a low molecular weight polyol compound refers to a polyol compound having 2 to 6 carbon atoms.

[0032] Examples of low molecular weight diol compounds include, for example, Ethylene glycol, Diethylene glycol, Triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and Examples include 1,4-butanediol.

[0033] Furthermore, as for low molecular weight triol compounds, Glycerin, 2-methyl-1,2,3-propanetriol, 1,2,4-butanetriol, and Examples include 1,2,6-hexanetriol.

[0034] The absorbent solution of the present invention only needs to contain at least one low molecular weight polyol compound, and multiple types can be used in combination. Among the low molecular weight polyol compounds, ethylene glycol is preferred. The content of the low molecular weight polyol compound in the absorbent solution of the present invention is preferably 2 to 30% by weight, and more preferably 5 to 30% by weight, based on the total mass of the acidic gas absorbent.

[0035] The absorbent liquid of the present invention contains water, and its content is not particularly limited.

[0036] Furthermore, the absorbent liquid of the present invention may also contain components other than the heterocyclic amine compound represented by formula (1), the low molecular weight polyol compound, and water, as needed, to the extent that they do not hinder the effects of the present invention. For example, it may contain a phosphate-based or other corrosion inhibitor to prevent corrosion of plant equipment, a silicone-based or other defoaming agent to prevent foaming, or an antioxidant to prevent deterioration of the acidic gas absorbent.

[0037] The acid gas removal method according to this embodiment involves bringing exhaust gas containing acid gas into contact with the above-mentioned acid gas absorbent, thereby absorbing, separating, and removing the acid gas from the exhaust gas containing acid gas.

[0038] The basic configuration of the carbon dioxide absorption and separation process includes a step of contacting an acidic gas absorbent with exhaust gas containing carbon dioxide to allow the acidic gas absorbent to absorb the carbon dioxide (carbon dioxide absorption step), and a step of heating the acidic gas absorbent obtained in the carbon dioxide absorption step, from which the carbon dioxide has been absorbed, to desorb and recover the carbon dioxide (carbon dioxide separation step).

[0039] The method for bringing a gas containing carbon dioxide into contact with an aqueous solution containing the above-mentioned acidic gas absorbent is not particularly limited, but can be carried out by, for example, bubbling the gas containing carbon dioxide into the acidic gas absorbent to absorb it, dropping the acidic gas absorbent in a mist form into a gas stream containing carbon dioxide (spray or atomizing method), or bringing the gas containing carbon dioxide and the acidic gas absorbent into countercurrent contact in an absorption tower filled with a porcelain or metal mesh packing material.

[0040] When absorbing a gas containing carbon dioxide into an aqueous solution, the temperature of the acidic gas absorbent is usually between room temperature and 60°C or lower. Preferably, it is 50°C or lower, and more preferably around 20-45°C.

[0041] The absorption rate of acidic gases increases with lower temperatures, but the lower limit of the processing temperature is determined by factors such as the gas temperature during the process and the heat recovery target. Carbon dioxide absorption is usually carried out at approximately atmospheric pressure. While it is possible to pressurize to higher pressures to improve absorption performance, it is preferable to perform the process at atmospheric pressure to minimize energy consumption required for compression.

[0042] Here, the carbon dioxide saturation absorption amount is the value obtained by measuring the amount of inorganic carbon in the acidic gas absorbent using an infrared gas concentration measuring device.

[0043] Methods for separating carbon dioxide from an acidic gas absorbent that has absorbed carbon dioxide and recovering pure or highly concentrated carbon dioxide include methods similar to distillation, where the acidic gas absorbent is heated and foamed in a pot for desorption; and methods that involve widening the liquid interface and heating in a tray column, spray column, or regeneration column packed with porcelain or metal mesh. This releases carbon dioxide from carbamate anions and bicarbonate ions.

[0044] The temperature of the acidic gas absorbent during carbon dioxide separation is typically 70°C or higher, preferably 80°C or higher, and more preferably around 90-120°C. While higher temperatures increase the amount of acidic gas recovered, raising the temperature also increases the energy required to heat the absorbent. Therefore, the temperature is determined by the gas temperature in the process and the heat recovery target. The pressure during carbon dioxide desorption is typically atmospheric pressure to 2 atmospheres. While it is possible to reduce the pressure to a lower level to improve desorption performance, it is preferable to use atmospheric pressure or higher to minimize the energy consumption required for decompression.

[0045] The acidic gas absorbent, after separating carbon dioxide, is sent back to the carbon dioxide absorption process for reuse (recycling). Furthermore, the heat generated during carbon dioxide absorption is typically cooled by heat exchange in a heat exchanger to preheat the aqueous solution injected into the regeneration tower during the aqueous solution recycling process.

[0046] The carbon dioxide recovered in this way is typically extremely pure, around 95-99% by volume. This pure or highly concentrated carbon dioxide can be used as a raw material for the synthesis of chemicals or polymers, or as a coolant for food freezing. In addition, it is possible to isolate and store the recovered carbon dioxide underground, a technology currently under development.

[0047] Of the processes described above, the step of separating carbon dioxide from the acidic gas absorbent and regenerating the acidic gas absorbent consumes the most energy. Therefore, by reducing the energy consumption in the acidic gas absorbent regeneration process, the cost of the carbon dioxide absorption and separation process can be reduced, making the removal of acidic gases from exhaust gases more economically advantageous.

[0048] According to this embodiment, by using the acidic gas absorbent of the above embodiment, the energy required for carbon dioxide desorption (regeneration process) can be reduced. Therefore, the carbon dioxide absorption and separation process can be carried out under economically advantageous conditions.

[0049] Furthermore, the amine compounds according to the above embodiment exhibit significantly higher corrosion resistance to metallic materials such as carbon steel compared to alkanolamines such as 2-aminoethanol, which have been conventionally used as acidic gas absorbents. Therefore, by using such an acidic gas absorbent in an acidic gas removal method, it becomes unnecessary to use expensive, high-grade corrosion-resistant steel in, for example, plant construction, thus offering cost advantages.

[0050] The acid gas removal apparatus according to this embodiment includes an absorption tower that removes acid gas from a gas containing acid gas by bringing the gas into contact with an acid gas absorbent, and a regeneration tower that removes acid gas from the acid gas absorbent that has absorbed acid gas and regenerates it, wherein the acid gas absorbent regenerated in the regeneration tower is reused in the absorption tower, and for example, the acid gas absorbent according to the above embodiment is used as the acid gas absorbent.

[0051] Figure 1 is a schematic diagram of an acid gas removal device according to an embodiment. This acid gas removal device 1 comprises an absorption tower 2 that brings a gas containing acid gas (hereinafter referred to as exhaust gas) into contact with an acid gas absorbent to absorb and remove the acid gas from the exhaust gas, and a regeneration tower 3 that separates the acid gas from the acid gas absorbent that has absorbed the acid gas and regenerates the acid gas absorbent. The following explanation will use the case where the acid gas is carbon dioxide as an example.

[0052] As shown in Figure 1, exhaust gas containing carbon dioxide, such as combustion exhaust gas discharged from a thermal power plant, is guided to the lower part of the absorption tower 2 through the gas supply port 4. This exhaust gas is pushed into the absorption tower 2 and comes into contact with the acidic gas absorbent supplied from the acidic gas absorbent supply port 5 at the top of the absorption tower 2. The acidic gas absorbent used is the acidic gas absorbent according to the embodiment described above.

[0053] The pH value of the acidic gas absorbent should be adjusted to at least 9 or higher, but it is best to select the optimal conditions as appropriate depending on the type, concentration, flow rate, etc., of the harmful gases contained in the exhaust gas.

[0054] Furthermore, in addition to the amine compounds and solvents such as water mentioned above, this acidic gas absorbent may also contain nitrogen-containing compounds, antioxidants, pH adjusters, and other compounds in any proportion to improve carbon dioxide absorption performance.

[0055] In this way, when the exhaust gas comes into contact with the acidic gas absorbent, the carbon dioxide in the exhaust gas is absorbed and removed by the acidic gas absorbent. After the carbon dioxide has been removed, the exhaust gas is discharged from the gas outlet 6 to the outside of the absorption tower 2.

[0056] The acidic gas absorbent that has absorbed carbon dioxide is sent to the heat exchanger 7 and heater 8, where it is heated and then sent to the regeneration tower 3. Once inside the regeneration tower 3, the acidic gas absorbent moves from the top to the bottom, during which time carbon dioxide is released from the acidic gas absorbent, and the acidic gas absorbent is regenerated.

[0057] The acidic gas absorbent regenerated in regeneration tower 3 is sent by pump 9 to heat exchanger 7 and absorbent liquid cooler 10, and then returned to absorption tower 2 through acidic gas absorbent supply port 5.

[0058] Meanwhile, the carbon dioxide separated from the acidic gas absorbent comes into contact with the reflux water supplied from the reflux drum 11 at the top of the regeneration tower 3 and is discharged to the outside of the regeneration tower 3.

[0059] The reflux water containing dissolved carbon dioxide is cooled in the reflux cooler 12, and then separated in the reflux drum 11 from the liquid component formed by condensed water vapor containing carbon dioxide. This liquid component is then led to the carbon dioxide recovery process via the carbon dioxide recovery line 13. Meanwhile, the reflux water from which the carbon dioxide has been separated is sent to the regeneration tower 3 by the reflux water pump 14.

[0060] According to the acidic gas removal device 1 of this embodiment, by using an acidic gas absorbent with excellent carbon dioxide absorption and desorption characteristics, it is possible to perform highly efficient absorption and removal of carbon dioxide. [Examples]

[0061] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0062] (Example 1) 55% by mass of hydroxyethylpiperazine (HEPZ) and 10% by weight of ethylene glycol (EG) were dissolved in water to prepare a 50 ml aqueous solution (hereinafter referred to as the absorption solution).

[0063] (Comparative Example 1) The absorbent solution was prepared in the same manner as in Example 1, except that ethylene glycol was not used in the absorbent solution of Example 1, and was evaluated in the same manner as in Example 1.

[0064] (Comparative Example 2) The evaluation was carried out in the same manner as in Example 1, except that hydroxyethylpiperazine was replaced with isopropylaminoethanol (IPAE).

[0065] (Comparative Example 3) The evaluation was the same as in Example 1, except that ethylene glycol was not used in Comparative Example 2.

[0066] (evaluation) Each prepared acidic gas absorption solution was filled into a test tube and immersed in a water bath heated to 40°C. A mixed gas containing 10% by volume of carbon dioxide (CO2) and 90% by volume of nitrogen (N2) gas was passed through the test tube at a flow rate of 500 mL / min for 120 minutes. The concentration of carbon dioxide (CO2) in the gas at the outlet of the test tube was measured using an infrared gas concentration meter to evaluate the amount of acidic gas absorbed. Next, the test tube containing the acid gas absorption solution, which had absorbed the acidic gas after the absorption amount was measured, was immersed in a 70°C water bath. The same mixed gas as above was passed through it for 60 minutes, and the carbon dioxide (CO2) concentration in the gas at the outlet of the test tube was measured using an infrared gas concentration meter to evaluate the amount of acidic gas released. Furthermore, the amount of amine compounds released was evaluated by recovering the amines released when 1% CO2 was passed through the acidic gas absorption solution in each example at 40°C, and measuring their concentration. The results obtained are shown in Table 1. In the table, the absorption amount, release amount, and emission amount are expressed as relative values ​​based on the evaluation results of the absorbent solution of Comparative Example 1. The absorption amount of the absorbent solution containing EG is expressed as a ratio of the increase or decrease compared to the absorption amount of the absorbent solution without EG. The product of the absorption amount and release amount (absorption amount × release amount), which corresponds to the recovery efficiency of acidic gases, is also shown in Table 1.

[0067] [Table 1]

[0068] In Example 1, compared to Comparative Example 1 which does not contain EG, the absorption amount tends to decrease, but the release amount increases significantly, thus improving the recovery efficiency. This effect cannot be obtained when using IPAE, which does not have a cyclic structure as an amine compound. Specifically, in Comparative Example 2 which contains EG and IPAE, compared to Comparative Example 3 which does not contain EG, the absorption amount decreases significantly, as does the release amount, resulting in a significant deterioration in recovery efficiency.

[0069] Furthermore, when comparing the emission properties of the amine compound in Example 1 and Comparative Example 1, the emission amount of HEPZ was constant regardless of the presence or absence of EG, and was less than that of Comparative Examples 2 and 3, which are acidic gas absorbents containing IPAE.

[0070] According to the embodiments described above, carbon dioxide can be efficiently separated and recovered without reducing the amount of carbon dioxide absorbed, and its emission is lower compared to other amines.

[0071] As described above, several embodiments have been explained, but these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0072] 1… Acid gas removal device, 2… Absorption tower, 3… Regeneration tower, 4… Gas supply port, 5… Acid gas absorbent 6... Supply port, 7... Gas outlet, 8... Heat exchanger, 9... Pump, 10... Absorption liquid cooler 11…Reflux drum, 12…Reflux condenser, 13…Recovered carbon dioxide line, 14…Reflux water pump

Claims

1. A heterocyclic amine compound represented by the following formula (1), A low molecular weight polyol compound selected from the group consisting of low molecular weight diol compounds and low molecular weight triol compounds, Water and, Acidic gas absorbent containing [a specific component]. 【Chemistry 1】 [In the formula, R １ Each of these independently represents a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group or aminoalkyl group having 1 to 6 carbon atoms. R ２ This represents a hydroxyalkyl group or aminoalkyl group having 2 to 6 carbon atoms. R １ and R ２ At least one of them contains a hydroxyalkyl group or an aminoalkyl group, p are each an independent integer between 2 and 4. The cyclic skeleton in the formula may contain oxygen as a component.

2. In the heterocyclic amine compound, R ２ The acidic gas absorbent according to claim 1, wherein is a 2-hydroxyethyl group or a 2-hydroxypropyl group.

3. The acidic gas absorbent according to claim 1 or 2, wherein the heterocyclic amine compound is 1-(2-hydroxyethyl)piperazine or 1-(2-hydroxypropyl)piperazine.

4. The acidic gas absorbent according to claim 1 or 2, wherein the content of the heterocyclic amine compound is 15 to 60% by mass, based on the total mass of the acidic gas absorbent.

5. The acidic gas absorbent according to claim 1 or 2, wherein the content of the low molecular weight polyol compound is 2 to 30% by weight, based on the total mass of the acidic gas absorbent.

6. The acidic gas absorbent according to claim 1 or 2, wherein the low molecular weight polyol compound is ethylene glycol.

7. A method for removing acidic gas, characterized by contacting a gas containing an acidic gas with an acidic gas absorbent according to claim 1 or 2 to remove the acidic gas from the gas containing the acidic gas.

8. An absorber that removes acidic gas from an acidic gas by contacting an acidic gas containing an acidic gas with the acidic gas absorbent described in claim 1 or 2, thereby causing the acidic gas absorbent to absorb the acidic gas, This regenerator removes the acidic gas from the acidic gas absorbent that has absorbed the acidic gas, and regenerates the acidic gas absorbent. It has, An acid gas removal device that reuses the acid gas absorbent, which has been regenerated in the aforementioned regenerator, in the aforementioned absorber.

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