GAS DEACIDIZING METHOD USING AN ABSORBENT SOLUTION WITH VAPORIZATION AND/OR PURIFICATION OF A FRACTION OF THE REGENERATED ABSORBENT SOLUTION

• US 20110081287A1
• Filed: 03/10/2010
• Published: 04/07/2011
• Est. Priority Date: 03/10/2009
• Status: Active Grant

• Current Assignee: IFP Energies Nouvelles
• Original Assignee: IFP Energies Nouvelles
• Inventors: BOUILLON, Pierre-Antoine, Jacquin, Marc
• Granted Patent: US 8,357,344 B2
• Time in Patent Office: Days
• US Class Current: 423/223
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1468 Removing hydrogen sulfide
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 3/52 by contacting with liquids; Regeneration of used liquids C01B3/508 takes precedence
• CPC Class Codes: C01B 32/50 Carbon dioxide
• CPC Class Codes: C10L 3/10 Working-up natural gas or synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants
• CPC Class Codes: F23J 15/04 using washing fluids scrubbers for removing solids only F23J15/022
• CPC Class Codes: F23J 2219/40 Sorption with wet devices, e.g. scrubbers
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 20/32 Direct CO2 mitigation
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

The gaseous effluent to be treated is contacted in column C1 with an absorbent solution selected for its property of forming two separable phases when it is heated. The regenerated absorbent solution is separated into two phases in drum B1; a fraction rich in water and a fraction rich in reactive compounds.

Separation allows to optimize the operations performed on the regenerated absorbent solution. On the one hand, separation allows to carry out vaporization, through reboiler R1, of a fraction of the absorbent solution, preferably containing a limited reactive compound concentration in relation to the absorbent solution, thus limiting their degradation. On the other hand, separation of the phases allows to reduce the amount of solution to be treated in order to remove the non-regeneratable salts and thus to reduce the costs linked with their elimination. Finally, separation allows to eliminate the degradation products by carrying out a specific and suitable purification for each phase.

The method can be applied to combustion fumes decarbonation and to natural gas or synthesis gas deacidizing.

Claims

1. ) A method of deacidizing a gaseous effluent comprising at least one acid compound of the group made up of hydrogen sulfide and carbon dioxide, wherein the following stages are carried out:

a) contacting gaseous effluent with an absorbent solution in a contacting zone so as to obtain a gaseous effluent depleted in acid compounds and an absorbent solution laden with acid compounds, the absorbent solution being selected for its property of forming two separable liquid fractions when it is heated,

b) regenerating the absorbent solution laden with acid compounds in a regeneration zone so as to release the acid compounds in gaseous form and to obtain a regenerated absorbent solution,

c) carrying out a stage of separation of a portion of the regenerated solution into a fraction enriched in water and a fraction enriched in reactive compounds,

d) carrying out at least one of the following operations;

i) vaporizing at least part of the water-enriched fraction so as to produce a vapour that is fed into regeneration zone,

ii) carrying out an operation of purification of the water-enriched fraction so as to produce a purified fraction that is fed into regeneration zone,

iii) carrying out an operation of purification of the fraction enriched in reactive compounds so as to produce a purified fraction that is fed into regeneration zone.

2. ) A method as claimed in claim 1, wherein operation i) is carried out using a reboiler.

3. ) A method as claimed in claim 1, wherein one of the following techniques is implemented in operation ii):

adsorption, ion exchange, distillation.

4. ) A method as claimed in claim 1, wherein one of the following techniques is implemented in operation iii):

adsorption, distillation.

5. ) A method as claimed in claim 2 wherein, after operation i) or ii), the water-enriched fraction is sent to contacting zone or regeneration zone.

6. ) A method as claimed in claim 4 wherein, after operation iii), the fraction enriched in reactive compounds is sent to contacting zone or regeneration zone.

7. ) A method as claimed in claim 1 wherein, prior to stage b), the absorbent solution laden with acid compounds is heated, a stream depleted in acid compounds is separated from the absorbent solution and the stream is recycled by feeding it into contacting zone.

8. ) A method as claimed in claim 7, wherein the absorbent solution laden with acid compounds is heated to a temperature ranging between 50°

C. and 150°

C.

9. ) A method as claimed in claim 1, wherein a second portion of the regenerated absorbent solution is recycled by being fed into the contacting zone.

10. ) A method as claimed in claim 1 wherein, in stage c), one of the following separation techniques is used:

decantation, centrifugation, filtration.

11. ) A method as claimed in claim 1, wherein the absorbent solution comprises a reactive compound in aqueous phase, the reactive compound being selected from the group consisting of:

amines, alkanolamines, polyamines, amino-acids, amino-acid alkaline salts, amides, ureas, alkali metal phosphates, carbonates and borates.

12. ) A method as claimed in claim 1, wherein the gaseous effluent is selected from the group made up of natural gas, synthesis gas, combustion fumes, refinery gas, Claus tail gas and biomass fermentation gas.