Absorbent liquid for CO2 and/or H2S, and apparatus and method using same

1. An absorbent liquid which absorbs at least one of CO 2 and H 2 S from a gas, consisting of:

water;

a secondary linear monoamine;

a tertiary linear monoamine; and

a secondary cyclic diamine,

wherein a concentration of each of the secondary linear monoamine, the tertiary linear monoamine and the secondary cyclic diamine is less than 30% by weight, the concentration of each of the secondary linear monoamine and the tertiary linear monoamine is 10% by weight or more, and the concentration of the secondary cyclic diamine is more than 1% by weight, and

wherein the secondary linear monoamine is at least one selected from the group consisting of: N-(methylamino)ethanol, N-(ethylamino)ethanol, N-(propylamino)ethanol, and N-(butylamino)ethanol, and

wherein the tertiary linear monoamine is at least one selected from the group consisting of: N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, 4-dimethylamino-1-butanol, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-di-n-butylaminoethanol, N-ethyl-N-methylethanolamine, 3-dimethylamino-1-propanol, and 2-dimethylamino-2-methyl-1-propanol,

wherein a total concentration of the secondary linear monoamine, the tertiary linear monoamine, and the secondary cyclic diamine is 70% by weight or less,

wherein the concentration of the secondary cyclic diamine is less than the concentration of the secondary linear monoamine and is less than the concentration of the tertiary linear monoamine in weight percent relative to the absorbent liquid,

wherein the concentration of the secondary linear monoamine is from 10% by weight to 28% by weight, and

wherein the concentration of the tertiary linear monoamine is 20% by weight or more.

2. The absorbent liquid according to claim 1 , wherein the tertiary linear monoamine is at least one selected from the group consisting of: N-butyldiethanolamine, 4-dimethylamino-1-butanol, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-di-n-butylaminoethanol, N-ethyl-N-methylethanolamine, 3-dimethylamino-1-propanol, and 2-dimethylamino-2-methyl-1-propanol.

3. The absorbent liquid according to claim 1 , wherein the secondary cyclic diamine is a piperazine derivative.

4. The absorbent liquid according to claim 3 , wherein the secondary cyclic diamine is piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, or a mixture thereof.

5. The absorbent liquid according to claim 1 , wherein the secondary linear monoamine is at least one selected from the group consisting of: N-(ethylamino)ethanol, and N-(butylamino)ethanol, and

wherein the tertiary linear monoamine is at least one selected from the group consisting of: N-ethyldiethanolamine, N-butyldiethanolamine and 2-(diethylamino)ethanol, and

wherein the secondary cyclic diamine is piperazine or 2-methylpiperazine.

6. The absorbent liquid according to claim 1 , wherein the concentration of the tertiary linear monoamine is the same as or less than the concentration of the secondary linear monoamine in weight percent relative to the absorbent liquid.

7. The absorbent liquid according to claim 1 , wherein a total concentration of the secondary linear monoamine and the tertiary linear monoamine is 20 to 55% by weight.

8. An apparatus for removing at least one of CO 2 and H 2 S from a gas, comprising:

an absorption tower which includes the absorbent liquid according to claim 1 ; and

a regeneration tower which regenerates the absorbent liquid containing the at least one CO 2 and H 2 S absorbed therein by heat of a reboiler.

9. A method for removing at least one of CO 2 and H 2 S from a gas, the method comprising:

absorbing at least one of CO 2 and H 2 S by bringing the absorbent liquid according to claim 1 into contact with the gas; and

regenerating the absorbent liquid containing the at least one of CO 2 and H 2 S absorbed therein by heat of a reboiler.