Absorbing solution, method and device for absorbing CO 2 or H 2 S or both

• US 8,147,593 B2
• Filed: 04/03/2006
• Issued: 04/03/2012
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Heavy Industries Engineering, Ltd. (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Kansai Electric Power Company Incorporated, Mitsubishi Heavy Industries, Ltd.
• Inventors: Mimura, Tomio, Yagi, Yasuyuki, Ogura, Kouki, Iijima, Masaki, Takashina, Toru, Tanaka, Hiroshi, Hirata, Takuya
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): PATEL, PANKTI R
• Application Number:
  US11/659,975
• Publication Number:
  US 20080078292A1
• Time in Patent Office: 2,192 Days
• Field of Search: 952/35, 423/229
• US Class Current: 95/235
• CPC Class Codes: B01D 2252/103 Water
• CPC Class Codes: B01D 2252/20405 Monoamines
• CPC Class Codes: B01D 2252/2041 Diamines
• CPC Class Codes: B01D 2252/20421 Primary amines
• CPC Class Codes: B01D 2252/20426 Secondary amines
• CPC Class Codes: B01D 2252/20431 Tertiary amines
• CPC Class Codes: B01D 2252/20447 containing a piperazine-ring
• CPC Class Codes: B01D 2252/20489 with two or more hydroxyl groups
• CPC Class Codes: B01D 2252/504 Mixtures of two or more absorbents
• CPC Class Codes: B01D 2252/604 Stabilisers or agents inhibiting degradation
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2258/06 Polluted air
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/526 Mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: C10L 3/10 Working-up natural gas or synthetic natural gas
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

An absorbing solution according to the present invention is an absorbing solution that absorbs CO₂ or H₂S in gas or both of CO₂ and H₂S. The absorbing solution is formed by adding desirably 1 to 20 weight percent of tertiary monoamine to a secondary-amine composite absorbent such as a mixture of secondary monoamine and secondary diamine. Consequently, it is possible to control degradation in absorbing solution amine due to oxygen or the like in gas. As a result, it is possible to realize a reduction in an absorption loss, prevention of malfunction, and a reduction in cost. This absorbing solution is suitably used in an apparatus for removing CO₂ or H₂S or both of CO₂ and H₂S.

Claims

1. An absorbing-solution that absorbs at least one of CO₂ and H₂S that are present in a gas, the absorbing-solution comprising:

a secondary-amine composite absorbent which is a mixture of a secondary monoamine and a secondary diamine; and

a tertiary monoamine that is added to the secondary-amine composite absorbent,

wherein the tertiary monoamine concentration with respect to the mixture of secondary monoamine and secondary diamine is set to 1 to 20 weight percent.

2. The absorbing-solution according to claim 1, wherein

the secondary monoamine is at least one member selected from the group consisting of 2-methylaminoethanol, 2-ethylaminoethanol, 2-n-propylaminoethanol, 2-n-butylaminoethanol, 2-n-pentylaminoethanol, 2-isopropylaminoethanol, 2-sec-butylaminoethanol, and 2-isobutylaminoethanol, and

the secondary diamine is at least one member selected from the group consisting of piperazine, 2-methylpiperazine, 2,3-dimethylpiperazine, 2,5-dimethylpiperazine, N,N′

-dimethylethanediamine, N,N′

-dimethylpropanediamine, N,N′

-diethylethanediamine, N,N′

-diethylpropanediamine, N,N′

-diisopropylethylenediamine, and N,N′

-ditertiary-butylethanediamine.

3. The absorbing-solution according to claim 1, wherein

the secondary monoamine is at least one member selected from the group consisting of 2-methylaminoethanol, 2-ethylaminoethanol, 2-n-propylaminoethanol, 2-n-butylaminoethanol, 2-n-pentylaminoethanol, 2-isopropylaminoethanol, 2-sec-butylaminoethanol, and 2-isobutylaminoethanol, and

the secondary diamine is at least one member selected from the group consisting of piperazine, 2-methylpiperazine, 2,3-dimethylpiperazine, and 2,5-dimethylpiperazine.

4. The absorbing-solution according to claim 1, wherein 2.5 weight percent to less than 100 weight percent of the secondary diamine is added to the secondary monoamine.

5. A removing apparatus which removes at least one of CO₂ and H₂S that are present in a gas, the removing apparatus comprising:

an absorber that receives the gas and causes the gas to come into contact with an absorbing-solution whereby at least one of CO₂ and H₂S is absorbed by the absorbing-solution; and

a regenerator that regenerates the absorbing-solution which has absorbed at least one of CO₂ and H₂S by removing any one of CO₂ and H₂S or both from the absorbing-solution, and that supplies the absorbing-solution from which at least one of CO₂ and H₂S has been removed to the absorber,

wherein the absorbing-solution includes a secondary-amine composite absorbent which is a mixture of a secondary monoamine and a secondary diamine and a tertiary monoamine that is added to the secondary-amine composite absorbent, wherein the tertiary monoamine concentration with respect to the mixture of secondary monoamine and secondary diamine is set to 1 to 20 weight percent.

6. The removing apparatus according to claim 5, wherein the mixture contains 2.5 to less than 100 weight percent of the secondary diamine based on the secondary monoamine.

7. A method of removing apparatus to remove at least one of CO₂ and H₂S that are present in a gas, the method comprising:

causing the gas to come into contact with an absorbing-solution whereby at least one of CO₂ and H₂S is absorbed by the absorbing-solution; and

regenerating the absorbing-solution that absorbed any one of CO₂ and H₂S by removing at least one of CO₂ and H₂S from the absorbing-solution,

wherein the causing step includes causing the gas to come into contact with an absorbing-solution that is regenerated in the regenerating step, and

wherein the absorbing-solution includes a secondary-amine composite absorbent which is a mixture of a secondary monoamine and a secondary diamine, and 1 to 20 weight-percent, based on the weight of said secondary-amine composite absorbent, of a tertiary monoamine that is added to the secondary-amine composite absorbent.

8. The method according to claim 7, wherein the mixture contains 2.5 to less than 100 weight percent of the secondary diamine based on the secondary monoamine.