[0001]The present invention relates to an absorber and method for removing CO 2 (carbon dioxide), H 2 S (hydrogen sulfide) or both, and CO 2 or H 2 S or both, and in particular, a CO 2 absorber for combustion exhaust gas. , CO 2 recovery device and method.
Background technology
[0002]
Conventionally, a method for recovering and removing 　various industrial gases such as natural gas and synthetic gas produced in chemical plants and acid gases contained in gases such as combustion exhaust gas (gas to be treated), especially CO 2 . Various methods have been proposed for. As such a method, there is a method of removing CO 2 and H 2 S in the combustion exhaust gas by contacting them with an alkanolamine aqueous solution as an absorbing liquid and recovering them.
[0003]
　Taking, for example, an absorption solution of monoethanolamine (MEA), which is a primary monoamine among alkanolamines, as an example of such an absorption solution, deterioration of the absorption solution itself progresses due to oxygen or the like in the combustion exhaust gas. For this reason, an absorbent solution obtained by blending a novel secondary monoamine with a secondary cyclic diamine or a predetermined primary monoamine having high steric hindrance is known (for example, Patent Document 1). Further, an absorption liquid obtained by adding a tertiary monoamine to a mixture of a secondary monoamine and a secondary cyclic diamine is known (for example, Patent Documents 2 to 3). Further, an absorption liquid obtained by mixing a predetermined primary monoamine, secondary monoamine and tertiary monoamine having high steric hindrance is known (for example, Patent Document 4). Further, an absorption liquid obtained by mixing a secondary monoamine, a secondary cyclic diamine and a tertiary monoamine is known (for example, Patent Document 5).
Prior art literature
Patent documents
[0004]
Pat .
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Gazette
Outline of the invention
Problems to be solved by the invention
[0005]
　However, each component of the absorbent liquid disclosed in Patent Documents 1 to 5 and their compounding ratio have a problem that a large amount of heat is required for the reboiler when the absorbent liquid is recycled.
[0006]
　In light of the above circumstances, the present invention can reduce the amount of heat of reboiler when reusing the absorbent liquid, and remove CO 2 , H 2 S or both of the absorbent liquid, and CO 2 or H 2 S or both of them. It is an object to provide an apparatus and a method.
Means to solve problems
[0007]
　According to the first aspect of the present invention, it is an absorption liquid that absorbs CO 2 , H 2S, or both of them in a gas, and is composed of (a) a secondary chain monoamine and (b) a tertiary chain monoamine. , (C) Secondary cyclic diamine as a component, the concentration of (a) secondary chain monoamine is more than 30% by weight and less than 45% by weight, and (b) tertiary chain monoamine. The absorbent is characterized by a concentration of more than 15% by weight and less than 30% by weight.
[0008]
　According to the second aspect of the present invention, there is an absorption tower that removes CO 2 or H 2 S or both by contacting a gas containing CO 2 or H 2 S or both with an absorbent solution , and CO 2 or It has an absorption liquid regeneration tower that regenerates a solution that has absorbed H 2S or both, and the solution that has been regenerated by removing CO 2 or H 2S or both in the absorption tower is regenerated in the absorption tower. It is a CO 2 and / or H 2 S removing device to be used, which is a CO 2 and / or H 2 S removing device characterized by using the absorbent solution .
[0009]
　According to the third aspect of the present invention, the gas containing CO 2 or H 2 S or both is brought into contact with the absorbing liquid to remove CO 2 or H 2 S or both in the absorption tower, and CO 2 is removed. Alternatively , the solution that has absorbed H 2S or both is regenerated in the absorption tower, and the solution that is regenerated by removing CO 2 or H 2S or both in the absorption tower is reused in the absorption tower. CO 2 and / or H 2 S, which is a method for removing CO 2 and / or H 2 S, which comprises removing CO 2 and / or H 2 S using the absorbent solution . It is in the removal method of.
The invention's effect
[0010]
　According to the present invention, it is an absorption liquid that absorbs CO 2 , H 2S, or both in a gas, and is (a) a secondary chain monoamine, (b) a tertiary chain monoamine, and (c). It contains secondary cyclic diamine as a component, (a) the concentration of the secondary chain monoamine is more than 30% by weight and less than 45% by weight, and (b) the concentration of the tertiary chain monoamine is 15% by weight. CO 2 , H 2 S or both absorbents and CO 2 or H 2 S or both removal devices and methods that can reduce the amount of revolving heat when reusing the absorbent by exceeding 30% by weight. Can be provided.
A brief description of the drawing
[0011]
FIG. 1 is a schematic diagram showing a configuration of a CO 2 recovery device according to the first embodiment.
FIG. 2 is a diagram showing the rate of reduction in the amount of revolving heat in the three-component absorbent liquid in Test Examples 1-1 to 1-5.
[Fig. 3] Fig. 3 is a diagram showing the rate of reduction of the amount of revolving heat in the three-component absorption liquid in Test Examples 2-1 to 2-5.
FIG. 4 is a graph showing the relationship between the absorbent amine component concentration (% by weight) and the riboira calorific value ratio in Test Example 1-6.
FIG. 5 is a graph showing the relationship between the absorbent amine component concentration (% by weight) and the riboira calorific value ratio in Test Example 3.
FIG. 6 shows the relationship between the weight ratio of “(b) tertiary chain monoamine / ((a) secondary chain monoamine + (c) secondary cyclic diamine)” in Test Example 6 and the riboira calorific value ratio. It is a graph which shows.
FIG. 7 is a graph showing the relationship between the weight ratio of “(b) tertiary chain monoamine / (a) secondary chain monoamine” in Test Example 7 and the calorie ratio of reboiler.
Embodiment for carrying out the invention
[0012]
　Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to this example, and when there are a plurality of examples, the present invention also includes a combination of the respective examples.
Example
[0013]
　The absorbent according to the embodiment of the present invention is an absorbent that absorbs CO 2 , H 2S, or both in a gas, and is (a) a secondary chain monoamine and (b) a tertiary chain monoamine . And (c) a secondary cyclic diamine as a component, the concentration of the (a) secondary chain monoamine is more than 30% by weight and less than 45% by weight, and (b) the tertiary chain monoamine. The concentration of is more than 15% by weight and less than 30% by weight.
[0014]
　Here, the concentration of (c) secondary cyclic diamine is lower than the concentration of (a) secondary chain monoamine and (b) lower than the concentration of tertiary chain monoamine in% by weight with respect to the absorbing liquid. Is preferable.
[0015]
　Further, the total concentration of (a) secondary chain monoamine, (b) tertiary chain monoamine, and (c) secondary cyclic diamine is preferably more than 46% by weight and 75% by weight or less.
[0016]
　The total concentration of each component (a) to (C) is preferably in the range of 50% by weight to 70% by weight, more preferably in the range of 55% by weight to 65% by weight, and is high. It is also preferable because it can reduce the amount of reboiler heat when the absorbent liquid is recycled.
[0017]
　(C) The lower limit of the secondary cyclic diamine concentration is preferably 1% by weight or more, more preferably 3% by weight or more.
[0018]
　As described above, by setting (a) a secondary chain monoamine, (b) a tertiary chain monoamine, and (c) a secondary cyclic diamine within the above concentration range, (a) a secondary chain monoamine and (a) a secondary chain monoamine can be obtained. c) Excellent CO 2 emission of (a) secondary chain monoamines and (b) tertiary chain monoamines while maintaining the CO 2 absorption capacity of the absorber due to the excellent CO 2 absorption of the secondary cyclic diamine. As a result , the CO 2 dissipation capacity of the absorption liquid can be improved, so that even when the concentration of the drug in the absorption liquid is high, the amount of revolving heat when regenerating the absorption liquid that has absorbed CO 2 can be reduced. can.
[0019]
　Further, the secondary chain monoamine (a) is preferably a compound represented by the chemical formula (I) represented by the following “Chemical formula 1”.
[Chemical 1]

[0020]
　Specifically, (a) as the secondary chain monoamine, a compound selected from at least one of, for example, N-methylaminoethanol, N-ethylaminoethanol, N-propylaminoethanol, N-butylaminoethanol and the like can be used. The present invention is not limited to this, although it can be mentioned. It should be noted that these may be combined.
[0021]
　Further, (b) the tertiary chain monoamine is preferably a compound represented by the chemical formula (II) represented by the following “Chemical formula 2”.
[Chemical 2]

[0022]
　Specifically, (b) tertiary chain monoamines include, for example, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, 4-dimethylamino-1-butanol, 2-dimethylaminoethanol, 2-diethylamino. Selected from at least one of ethanol, 2-di-n-butylaminoethanol, N-ethyl-N-methylethanolamine, 3-dimethylamino-1-propanol, 2-dimethylamino-2-methyl-1-propanol and the like. However, the present invention is not limited to this. It should be noted that these may be combined.
[0023]
　Further, (c) the secondary cyclic diamine is a piperazine derivative. Examples of such piperazine derivatives include compounds such as piperazine (C 4 H 10 N 2 ), 2-methylpiperazine (C 5 H 12 N 2 ), and 2,5-dimethylpiperazine (C 6 H 14 N 2 ), or these. Can be mentioned as a mixture of.
[0024]
　The general feature of the absorbent component (a) secondary chain monoamine in the present invention is that the reaction with CO 2 in the exhaust gas produces a carbamate containing the absorbent amine in the molecule and immobilizes CO 2 . Therefore, the absorption capacity has high characteristics.
　However, under high concentration conditions, it is necessary to prevent deterioration of absorption rate, absorption performance and regeneration performance due to an increase in the viscosity of the absorbent liquid.
　On the other hand, (b) tertiary chain monoamine, which is another component of the present invention, does not generate carbamate by reaction with CO 2 , but dissolves CO 2 mainly as a bicarbonate, so that the absorption performance is ( a) Although it is not as good as secondary chain monoamine, it can relatively moderate the increase in the viscosity of the absorbent liquid even under high concentration conditions, and has excellent regeneration performance.
[0025]
　In the present invention, based on the characteristics of both of the above-mentioned absorbent liquid components, the composition of the absorbent component that can suppress the increase in the viscosity of the absorbent liquid, maintain the absorption performance, and reduce the amount of revolving heat by preventing the deterioration of the regeneration performance even under the high concentration condition of the absorbent. (A) Class 2 as an absorbent composition that sets the concentration of (b) tertiary chain monoamine in a relatively high suitable range even under the composition condition of high concentration of secondary chain monoamine. It contains a chain monoamine, (b) a tertiary chain monoamine, and (c) a secondary cyclic diamine as components, and (a) the concentration of the secondary chain monoamine is more than 30% by weight and less than 45% by weight. It has been found that (b) the concentration of the tertiary chain monoamine is more than 15% by weight and less than 30% by weight.
[0026]
　Here, the measurement of the increase in viscosity of the absorbing liquid is regenerated in the CO 2 absorbing tower that removes CO 2 in the exhaust gas and the absorbing liquid that releases the absorbed CO 2 and recycles the regenerated tower as the absorbing liquid. The viscosity (A) at the point where the CO 2 absorbing liquid (lean solution) is supplied into the CO 2 absorbing tower and the CO 2 absorbing liquid ( CO 2 absorbing liquid) that absorbed CO 2 at the CO 2 recovery part of the CO 2 absorbing tower. The viscosity (B) of the rich liquid) is measured, and it has been confirmed that the increase in the viscosity of the absorbed liquid can be suppressed by using the formulation of the present invention as shown in a test example described later.
[0027]
　Further, regarding the blending ratio of each component (component a, component b, component c), (b) tertiary chain is obtained with respect to the total weight of (a) secondary chain monoamine and (c) secondary cyclic diamine. It is preferable to specify that the weight ratio of monoamine is more than 0.3 and less than 0.85.
[0028]
　By defining in this way, a suitable "(b) tertiary chain monoamine / ((A) Secondary chain monoamine + (c) Secondary cyclic diamine) ”It is possible to provide an absorbing liquid having excellent energy saving by weight ratio.
[0029]
　Regarding the blending ratio of each component (component a and component b), the weight ratio of (b) tertiary chain monoamine to (a) secondary chain monoamine is more than 0.5 and less than 1.0. It is preferable to specify in.
[0030]
　By defining in this way, (b) a suitable "(b) tertiary chain monoamine / (a) secondary chain monoamine" in an absorbent solution containing a tertiary chain monoamine as an absorbent component at a high concentration. It is possible to provide an absorbent liquid having excellent energy saving by weight ratio.
[0031]
　In the present invention, for example, the absorption temperature of the absorption tower of the chemical absorption method at the time of contact with exhaust gas containing CO 2 or the like is preferably in the range of 30 to 80 ° C. Further, a corrosion inhibitor, a deterioration inhibitor and the like are added to the absorbent liquid used in the present invention, if necessary.
[0032]
In addition, the CO 2 partial pressure at the inlet of the CO 2 absorption tower at the time of absorption to absorb CO 2 　in the gas to be treated should be a low CO 2 partial pressure (for example, 0.003 to 0.1 MPa) for chemical absorption. Preferred from the application of the law.
[0033]
　In the present invention, the regeneration temperature in the regeneration tower that releases CO 2 and the like from the absorption liquid that has absorbed CO 2 and the like is the bottom of the absorption liquid regeneration tower when the pressure inside the regeneration tower is 130 to 200 kPa (absolute pressure). The temperature is preferably 110 ° C. or higher. This is because regeneration at a temperature lower than 110 ° C. requires a large circulation amount of the absorbing liquid in the system, which is not preferable from the viewpoint of regeneration efficiency. More preferably, regeneration at 115 ° C. or higher is preferable.
[0034]
　Examples of the gas treated by the present invention include, but are not limited to, coal gasification gas, synthetic gas, coke oven gas, petroleum gas, natural gas, combustion exhaust gas and the like, and CO 2 Any gas may be used as long as it contains an acid gas such as H2S or H2S .
[0035]
The process that can be adopted by the method of removing CO 2 and / or H 2S 　in the gas of the present invention is not particularly limited, but an example of a removing device that removes CO 2 will be described with reference to FIG.
[0036]
FIG. 1 is a schematic view showing the configuration of the 　CO 2 recovery device according to the first embodiment. As shown in FIG. 1, the CO 2 recovery device 12 according to the first embodiment cools an exhaust gas 14 containing CO 2 and O 2 discharged from an industrial combustion facility 13 such as a boiler or a gas turbine with cooling water 15. The exhaust gas cooling device 16 is brought into contact with the exhaust gas 14 containing cooled CO 2 and the CO 2 absorbing liquid (hereinafter, also referred to as “absorbing liquid”) 17 for absorbing CO 2 to generate CO 2 from the exhaust gas 14 . CO 2 is regenerated by releasing CO 2 from a CO 2 absorption tower 18 having a CO 2 recovery unit 18A to be removed and a CO 2 absorbing solution ( hereinafter , also referred to as “ rich solution”) 19 that has absorbed CO 2 . It has an absorption liquid regeneration tower 20 and the like. Then, in this CO 2 recovery device 12, CO 2 is generated in the absorbent liquid regeneration tower 20. The regenerated CO 2 absorbing liquid (hereinafter, also referred to as “lean solution”) 17 from which the above is removed is reused as a CO 2 absorbing liquid in the CO 2 absorbing tower 18 .
[0037]
　In FIG. 1, reference numeral 13a is a flue, 13b is a chimney, and 34 is steam condensed water. The CO 2 recovery device 12 may be retrofitted to recover CO 2 from an existing exhaust gas source , or may be simultaneously attached to a new exhaust gas source. A damper that can be opened and closed is installed in the line of the exhaust gas 14, and is opened when the CO 2 recovery device 12 is in operation. Although the exhaust gas source is operating, it is set to be closed when the operation of the CO 2 recovery device 12 is stopped.
[0038]
　In the CO 2 recovery method using the CO 2 recovery device 12 , first, the exhaust gas 14 from the industrial combustion equipment 13 such as a boiler or a gas turbine containing CO 2 is boosted by the exhaust gas blower 22 and then the exhaust gas cooling device. It is sent to 16, where it is cooled by the cooling water 15 and sent to the CO 2 absorption tower 18.
[0039]
　In the CO 2 absorption tower 18, the exhaust gas 14 is in countercurrent contact with the CO 2 absorption liquid 17 which is the amine absorption liquid according to the present embodiment, and the CO 2 in the exhaust gas 14 is absorbed by the CO 2 absorption liquid 17 by a chemical reaction. Will be done. The CO 2 removed exhaust gas after CO 2 is removed by the CO 2 recovery unit 18A is the circulating washing water 21 and the gas liquid containing the CO 2 absorbing liquid supplied from the nozzle in the water washing unit 18B in the CO 2 absorption tower 18. Upon contact, the CO 2 absorbing liquid 17 accompanying the CO 2 removed exhaust gas is recovered, and then the CO 2 removed exhaust gas 23 is released to the outside of the system. Further, the rich solution 19 which is a CO 2 absorbing liquid that has absorbed CO 2 is boosted by the rich solution pump 24, and the CO 2 absorbing liquid 17 regenerated in the absorbing liquid regeneration tower 20 in the rich lean solution heat exchanger 25. It is heated by the lean solution and supplied to the absorption liquid regeneration tower 20.
[0040]
　The rich solution 19 discharged from the upper part of the absorption liquid regeneration tower 20 to the inside causes an endothermic reaction by the water vapor supplied from the bottom part, and releases most of CO 2 . The CO 2 absorption liquid that has released a part or most of CO 2 in the absorption liquid regeneration tower 20 is called a semi-lean solution. By the time the semi-lean solution reaches the bottom of the absorption liquid regeneration tower 20, it becomes a CO 2 absorption liquid (lean solution) 17 from which almost all CO 2 has been removed . A part of this lean solution 17 is superheated by steam 27 in the reboiler 26, and steam for CO 2 desorption is supplied to the inside of the absorption liquid regeneration tower 20.
[0041]
　On the other hand, from the top of the absorption liquid regeneration tower 20, a CO 2 accompanying gas 28 accompanied by water vapor released from the rich solution 19 and the semi-lean solution is derived in the tower, the water vapor is condensed by the condenser 29, and the separation drum 30 is used. The water is separated at, the CO 2 gas 40 is released to the outside of the system, and the CO 2 gas 40 is separately compressed by the compressor 41 and recovered. After passing through the separation drum 43, the compressed / recovered CO 2 gas 42 is either press-fitted into an oil field using an enhanced oil recovery method (EOR) or stored in an aquifer for warming. We are taking measures. The recirculated water 31 separated and recirculated from the CO 2 concomitant gas 28 accompanied by water vapor by the separation drum 30 is supplied to the upper part of the absorption liquid regeneration tower 20 and the washing water 21 side by the recirculation water circulation pump 35, respectively. The regenerated CO 2 absorbent (lean solution) 17 is cooled by the rich solution 19 in the rich lean solution heat exchanger 25, subsequently boosted by the lean solution pump 32, and further by the lean solution cooler 33. After being cooled, it is supplied into the CO 2 absorption tower 18. It should be noted that, in this embodiment, only the outline thereof is explained, and some of the attached devices are omitted.
[0042]
　Hereinafter, suitable test examples showing the effects of the present invention will be described, but the present invention is not limited thereto.
[0043]
[Test Examples 1-1 to 1-5] CO 2
was absorbed 　using an absorption test apparatus (not shown ). 　FIG. 2 shows a three-component absorption liquid ((a) secondary chain monoamine, (b) tertiary chain monoamine, and (c) secondary cyclic diamine dissolved in water in Test Examples 1-1 to 1-5. It is a figure which shows the reboiler calorie reduction rate of (the).
[0044]
　(A) N-butylaminoethanol (more than 30% by weight and less than 45% by weight) as a secondary chain monoamine, (b) N-methyldiethanolamine (more than 15% by weight and less than 30% by weight) as a tertiary chain monoamine. , (C) 2-Methylpiperazine (lower concentration than (a) and (b)) as a secondary cyclic diamine is dissolved and mixed in water, and the total concentration of the absorber amine component is 55% by weight in Test Example 1. An absorption solution of -1 was prepared.
[0045]
　The absorption liquid of Test Example 1-2 was prepared in the same manner as in Test Example 1-1 except that (c) secondary cyclic diamine was piperazine.
[0046]
　The absorption liquid of Test Example 1-3 was prepared in the same manner as in Test Example 1-1 except that (b) the tertiary chain monoamine was N-butyldiethanolamine.
[0047]
　The absorption liquid of Test Example 1-4 was prepared in the same manner as in Test Example 1-1 except that (a) secondary chain monoamine was N-ethylaminoethanol and (c) secondary cyclic diamine was piperazine. did.
[0048]
　Test Example 1-5 was prepared in the same manner as in Test Example 1-4 except that (b) the tertiary chain monoamine was N-ethyldiethanolamine.
[0049]
　Further, as a comparative example, monoethanolamine (MEA) was dissolved and mixed in water at 30% by weight to prepare an absorption solution of Comparative Example 1. The component compositions of each test example and comparative example are shown in Table 1 below.
[0050]
[table 1]

[0051]
　 The reboiler calorific value
　when the absorbent liquids of each test example and the comparative example were used was measured, and the reboiler calorific value of each test example was used as the calorific value ratio as compared with the case where the absorbent liquid of the comparative example was used. evaluated. The evaluation results are shown in FIG.
[0052]
　As shown in FIG. 2, assuming that the calorific value when the absorbent liquid of Comparative Example 1 is used is 1, the reboiler calorific value ratio when the absorbent liquids of Test Examples 1-1 and 1-2 are used is less than 0.90. When the absorbents of Test Examples 1-3 to 1-5 were used, the revolving calorific value ratio was less than about 1.00.
[0053]
[Test Examples 2-1 to 2-5]
　Further, in the absorbent solution of Test Examples 1-1 to 1-5, the total concentration of the amine component of the absorbent was increased from 55% by weight to 65% by weight, and Test Example 2- Absorbents 1 to 2-5 were prepared. The composition of the components of Test Examples 2-1 to 2-5 is shown in Table 2 below. In addition, Comparative Example 1 is the same as Table 1 described above, and the formulation is omitted. FIG. 3 shows the evaluation results evaluated in the same manner as in Test Example 1-1.
[0054]
[Table 2]

[0055]
　As shown in FIG. 3, assuming that the calorific value when the absorbent liquid of Comparative Example 1 is used is 1, the reboiler calorific value ratio when the absorbent liquids of Test Examples 2-1 and 2-2 are used is less than 0.90. When the absorbents of Test Examples 2-3 to 2-5 were used, the revolving calorific value ratio was less than about 1.00.
[0056]
　Based on the above, Test Example 1 using a three-component absorption liquid ((a) secondary chain monoamine, (b) tertiary chain monoamine, (c) secondary cyclic diamine dissolved in water) was used. It was found that the absorbents of -1 to 1-5 and Test Examples 2-1 to 2-2 can reduce the calorific value of reboiler as compared with Comparative Example 1 using monoethanolamine. In particular, it was found that the absorption liquids of Test Examples 1-1 to 1-2 and Test Examples 2-1 to 2-2 can reduce the amount of heat of the reboiler by 10% or more.
　Therefore, even if the absorption liquid has a high concentration, it is possible to provide an absorption liquid having excellent energy saving performance as compared with the conventional one, and when regenerating the absorption liquid that has absorbed CO 2 or H 2S in the gas or both of them. It was possible to reduce the amount of reboiler heat.
[0057]
[Test Example 1-6]
　In Test Example 1-6, an absorbent solution having the composition of Test Example 1-1 was used, and (a) the concentration of N-butylaminoethanol as a secondary chain monoamine was fixed at 32% by weight. (B) The absorption solution of Test Example 1-6 was prepared by changing the component concentration of N-methyldiethanolamine as a tertiary chain monoamine. The comparative example is the same as that prepared by dissolving and mixing the above-mentioned monoethanolamine (MEA) in water at 30% by weight. The composition of the components of the test example is shown in Table 3 below. The results are shown in FIG. FIG. 4 is a graph showing the relationship between the absorbent amine component concentration (% by weight) and the riboira calorific value ratio in Test Example 1-6.
[0058]
[Table 3]

[0059]
　As shown in FIG. 4, it was found that (b) N-methyldiethanolamine as a tertiary chain monoamine can reduce the calorific value of reboiler by about 9% or more in the range of more than 15% by weight and 33% by weight.
[0060]
[Test Example 3]
　Prior art (Comparative Example 2) in which the absorbent solution having the composition of Test Example 1-2 described above is used as the absorbent solution of Test Example 3 and the total concentration (% by weight) of the absorbent amine component is high. , A comparative test with Comparative Example 3) was performed.
　Here, Comparative Example 2 is a compounding composition of Test Example 6 of JP2013-086079, and Comparative Example 3 is a compounding composition of Test Example 1-2 of JP-A-2017-64645. The compounding composition is shown in Table 3. FIG. 5 is a graph showing the relationship between the absorbent amine component concentration (% by weight) and the riboira calorific value ratio in Test Example 3. The comparison standard on the vertical axis in FIG. 5 is Comparative Example 1 prepared by dissolving and mixing the above-mentioned monoethanolamine (MEA) in water in an amount of 30% by weight. The composition of the components of Test Example 3 and Comparative Examples 2 and 3 is shown in Table 4 below.
[0061]
[Table 4]

[0062]
　Here, the concentrations in Test Example 3 and Comparative Examples 2 and 3 were adjusted as follows.
　Under the condition that the total absorption agent amine concentration is 55% by weight, (a) secondary chain monoamine concentration is A 55 % by weight, (b) tertiary chain monoamine concentration is B 55 % by weight, and (c) secondary cyclic. When the diamine concentration was C 55 % by weight and the total absorbent amine concentration was changed to T% by weight, the (a) secondary chain monoamine concentration was A T % by weight and (b) the tertiary chain monoamine. Assuming that the concentration is B T % by weight and (c) the secondary cyclic diamine concentration is C T weight%, the compounding ratio of each component in each example is A 55 : B 55 : C 55 = AT : B T : C T = . The concentration (% by weight) of each component under the condition that the total concentration of the absorber amine is T is fixed is calculated for each composition as shown in Table 5 below.
[0063]
[Table 5]

[0064]
　As shown in FIG. 5, under the absorbent component compounding ratio conditions of Comparative Example 2 and Comparative Example 3 of the prior art, the reduction of the revolving calorific value was slowed down or the reboiler calorific value was deteriorated under the absorbent agent high concentration condition. On the other hand, it was found that the absorbent solution of Test Example 3 can reduce the amount of heat of the reboiler even under the high concentration condition of the absorbent. In particular, when the total concentration of the absorbent amine was as high as 55% by weight or more, the absorbent solution of Test Example 3 was able to further reduce the calorific value of the reboiler.
[0065]
[Test Example 4, Test Example 5]
　As the absorbent solution of Test Example 4, the absorbent solution having the composition of Test Example 1-2 is used, and the total concentration (% by weight) of the amine component of the absorbent is a prior art under high concentration conditions. A comparative test of changes in the viscosity of the absorbent liquid with Comparative Example 2 and Comparative Example 3) was performed.
　Comparative Example 2 is a compounding composition of Test Example 6 of JP2013-086079, and Comparative Example 3 is a compounding composition of Test Example 1-2 of JP-A-2017-64645.
[0066]
　The viscosity of the absorbent is measured by measuring the viscosity (A) of the absorbent liquid before being introduced into the CO 2 absorption tower 18 of the CO 2 recovery device 12 in FIG. 1 and the absorption of the liquid pool after absorbing CO2 of the exhaust gas 14. The viscosity (B) of the liquid was measured. Specifically, in the CO 2 recovery device in FIG. 1, the circulating absorption liquid is regenerated in the regeneration tower, and the regenerated CO 2 absorption liquid (lean solution) 17 is boosted by the solution pump 32. Further, after being cooled by the lean solution cooler 33 , the measurement was performed at the point (A) when the liquid was supplied into the CO 2 absorption tower 18. On the other hand, the viscosity B was measured at the point (B) of the liquid pool at the bottom of the CO 2 absorbing liquid (rich liquid) 19 that absorbed CO 2 in the CO 2 recovery unit 18 .
[0067]
　The compounding ratio of each absorbent component of Test Example 4 is the total concentration (55% by weight) of the fixed absorbent amine component of Test Example 1-2 shown in Table 1. The compounding ratio of each absorbent component of Test Example 5 is the total concentration (65% by weight) of the fixed absorbent amine component of Test Example 2-2. The reference for the viscosity was set to 1 as the value of (viscosity A) measured at the point (A) when the CO 2 absorption tower 18 was supplied into the CO 2 absorption tower 18 in Test Example 3 . The results are shown in Tables 6 and 7.
[0068]
[Table 6]

[0069]
[Table 7]

[0070]
　As shown in Tables 6 and 7, in the absorption liquids having the compositions of Test Example 4 and Test Example 5, the increase in the viscosity of the absorption liquid is suppressed even under the condition of high concentration of the absorbent, as compared with Comparative Examples 2 and 3 of the prior art. It turned out that
[0071]
[Test Example 6]
　In Test Example 6, the absorbent solution having the composition of Test Example 1-1 was used, and (a) the concentration of N-butylaminoethanol as a secondary chain monoamine was fixed at 32% by weight, and (b) 3 Test Example 6 in which the component ratio of N-methyldiethanolamine as a secondary chain monoamine ((b) tertiary chain monoamine / ((a) secondary chain monoamine + (c) secondary cyclic diamine)) weight ratio was changed. Absorbent solution was prepared.
　A comparative example was prepared by dissolving and mixing the above-mentioned monoethanolamine (MEA) in 30% by weight in water. The composition of the components of the test example is shown in Table 8 below. The results are shown in FIG. FIG. 6 is a graph showing the relationship between the weight ratio of “(b) tertiary chain monoamine / ((a) secondary chain monoamine + (c) secondary cyclic diamine)” in Test Example 6 and the riboira calorific value ratio. be.
[0072]
[Table 8]

　As shown in FIG. 6, the weight ratio of "(b) tertiary chain monoamine / ((a) secondary chain monoamine + (c) secondary cyclic diamine)" is more than 0.3 and 0. It was found that in the range of 85, the calorific value of reboiler can be reduced by about 9% or more.
[0073]
[Test Example 7]
　In Test Example 6, the absorbent solution having the composition of Test Example 1-1 was used, and (a) the concentration of N-butylaminoethanol as a secondary chain monoamine was fixed at 32% by weight, and (b) 3 An absorption solution of Test Example 5 was prepared in which the component ratio of N-methyldiethanolamine ((b) tertiary chain monoamine / (a) secondary chain monoamine) weight ratio was changed as the class chain monoamine.
　A comparative example was prepared by dissolving and mixing the above-mentioned monoethanolamine (MEA) in 30% by weight in water. The composition of the components of the test example is the same as that in Table 7. The results are shown in FIG. FIG. 7 is a graph showing the relationship between the weight ratio of “(b) tertiary chain monoamine / (a) secondary chain monoamine” and the riboira calorific value ratio in Test Example 7.
[0074]
　As shown in FIG. 6, in the range of "(b) tertiary chain monoamine / (a) secondary chain monoamine" weight ratio of more than 0.5 and 1.0, the amount of revolving heat can be reduced by about 9% or more. I understood.
[0075]
　The combination of (a) secondary chain monoamine, (b) tertiary chain monoamine, and (c) secondary cyclic diamine of the present invention is not limited to those whose effects have been demonstrated in this test example. No. Next, Tables 9 to 12 show an example as a suitable one other than the test example of these preferable combinations.
[0076]
[Table 9]

[0077]
　Table 9 is an example of a preferable combination when (a) N-methylaminoethanol is used as the secondary chain monoamine.
[0078]
[Table 10]

[0079]
　Table 10 is an example of a preferable combination when (a) N-ethylaminoethanol is used as the secondary chain monoamine.
[0080] [0080]
[Table 11]

[0081]
　Table 11 is an example of a preferable combination when (a) N-propylaminoethanol is used as the secondary chain monoamine.
[0082]
[Table 12]

[0083]
　Table 12 is an example of a preferable combination when (a) N-butylaminoethanol is used as the secondary chain monoamine.
Description of the sign
[0084]
　12 CO 2 recovery device
　13 Industrial combustion equipment
　14 Exhaust gas
　16 Exhaust gas cooling device
　17 CO 2 absorption liquid (lean solution)
　18 CO 2 absorption tower
　19 CO 2 absorption liquid that absorbed CO 2 (rich solution)
　20 Absorption liquid regeneration tower
　21 Cleaning water　

WE CLAIMS

An absorbent that absorbs CO 2 , H 2S , or both in a 　gas, and includes
(a) a secondary chain monoamine,
(b) a tertiary chain monoamine, and
(c) a secondary cyclic diamine. (A) The concentration of the secondary chain monoamine
　is more than 30% by weight and less than 45% by weight, and the concentration of the (b) tertiary chain monoamine is more than 15% by weight and 30% by weight. Absorbent characterized by less than.
[Claim 2]
　In claim 1,
　the concentration of the (c) secondary cyclic diamine
　is lower than the concentration of the (a) secondary chain monoamine in% by weight with respect to the absorbing solution, and the concentration of the (b) tertiary chain monoamine is higher. An absorbent that is characterized by a concentration lower than that of.
[Claim 3]
　In claim 1 or 2, the weight ratio of the (b) tertiary chain monoamine
　to the total weight of the (a) secondary chain monoamine and the (c) secondary cyclic diamine
exceeds 0.3. An absorbent liquid characterized by being less than 0.85.
[Claim 4]
　The absorption liquid according to any one of claims 1 to 3,
　wherein the secondary chain monoamine (a) is a compound represented by the following formula (I).
[Chemical 1]

[Claim 5]
　The absorption liquid according to any one of claims 1 to 4,
　wherein the tertiary chain monoamine (b) is a compound represented by the following formula (II).
[Chemical 2]

[Claim 6]
　The absorption liquid according to any one of claims 1 to 5,
　wherein the secondary cyclic diamine (c) is a piperazine derivative.
[Claim 7]
　In any one of claims 1 to 6,
　the total concentration of the (a) secondary chain monoamine, the (b) tertiary chain monoamine, and the (c) secondary cyclic diamine is the total concentration. An absorbent liquid characterized by being more than 46% by weight and 75% by weight or less.
[Claim 8]
An absorption tower that removes CO 2 or H 2 S or both 　by contacting a gas containing CO 2 or H 2 S or both with an absorbent solution, and a solution that absorbs CO 2 or H 2 S or both. CO 2 or H 2 S or H 2 S or H 2 S or H 2 S or H 2 S or A CO 2 and / or H 2S removing device, which is a removing device for both of
　them, wherein the absorbing solution according to any one of claims 1 to 7 is used .
[Claim 9]
The gas containing 　CO 2 or H 2 S or both was brought into contact with the absorbing liquid to remove CO 2 or H 2 S or both in the absorption tower, and CO 2 or H 2 S or both were absorbed. CO 2 or H 2 S or its _ A method for removing both CO 2 or H 2 S, which comprises removing CO 2 or H 2 S or both of them 　using the absorbent solution according to any one of claims 1 to 7. Both removal methods.