METHOD FOR RECLAIMING OF CO2 ABSORBENT AND A RECLAIMER

• US 20120125196A1
• Filed: 06/09/2010
• Published: 05/24/2012
• Est. Priority Date: 06/09/2009
• Status: Active Grant

• Current Assignee: AKER Carbon Capture Norway As (Aker Carbon Capture AS)
• Original Assignee: Aker Clean Carbon AS (Akastor ASA)
• Inventors: Woodhouse, Simon, Bade, Otto Morten, Haaland, Anne-Helene, Gorset, Oddvar, Berg, Bjorn Magnus
• Granted Patent: US 8,808,429 B2
• Time in Patent Office: Days
• US Class Current: 95/193
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A method for reclaiming CO2 absorbing chemical(s) from a lean aqueous CO2 absorbent leaving a regeneration column (8), where lean absorbent (30) is withdrawn and flashed (31) to generate a vapor that is compressed (34) and returned into the regeneration column as stripper gas (37), where a part of the lean absorbent (20) is withdrawn and introduced into a reclaimer (21) in which the lean absorbent is boiled to generate a gas phase (23) that is withdrawn and returned into the regeneration column as reclaimed absorbent, and a liquid phase containing impurities (24), wherein the gaseous phase that is withdrawn from the reclaimer is compressed (34) together with the vapor part (33) from the flashing of the lean absorbent, to generate a pressure in the reclaimer that is lower than the pressure in the regeneration column, and a reboiler (11) for carrying out the method, are described.

Claims

1. A method for reclaiming one or more CO₂ absorbing chemical(s) from a lean aqueous CO₂ absorbent leaving a regeneration column in which CO₂ has been released, or desorbed, from the lean aqueous CO₂ absorbent, and the released CO₂ is withdrawn from a top of a regeneration column for further treatment, and the lean aqueous CO₂ absorbent, or CO₂ depleted absorbent, is collected at a bottom of the regeneration column and withdrawn therefrom, where at least a part of the lean aqueous CO₂ absorbent leaving the regeneration column is introduced into a reboiler where the lean aqueous CO₇ absorbent is heated to generate steam and vaporized absorbent that is introduced into the regeneration column as stripping gas, where the lean aqueous CO₂ absorbent is withdrawn and is returned to an absorption column, and where a part of the lean aqueous CO₂ absorbent is withdrawn and introduced into a reclaimer in which the lean aqueous CO₂ absorbent is boiled to generate a gas phase that is withdrawn and returned into the regeneration column as reclaimed absorbent, and a liquid phase containing impurities, heat stable salts, and degradation products from absorbing chemical(s) and other chemicals that are withdrawn from the reclaimer for deposition, wherein the lean aqueous CO₇ absorbent withdrawn from the regeneration column is flashed to generate a vapour that is compressed and returned into the regeneration column as stripper gas, and a liquid phase that is returned to the absorption column, where the gaseous phase that is withdrawn from the reclaimer is compressed together with the vapour part from flashing of the lean absorbent, to generate a pressure in the reclaimer that is lower than a pressure in the regeneration column.

2. The method of claim 1, wherein the pressure in the reclaimer is further reduced by means of a suction means for withdrawal of the gaseous phase from the reclaimer.

3. The method of claim 2, wherein the suction means is a vacuum system, an ejector or a compressor.

4. The method of claim 1, wherein the pressure in the reclaimer is at least 0.2 bar lower than the pressure in the regeneration column.

5. The method of claim 4, wherein the pressure in the reclaimer is at least 0.3 bar lower than the pressure in the regeneration column.

8. The regenerator according to claim 5, wherein an ejector pump is arranged in the reclaimer withdrawal line for further reduction of the pressure in the reclaimer.

6. A regenerator for a liquid absorbent for CO₂ comprising:

a regeneration column;

a rich absorbent line for introduction of rich absorbent into the regeneration column;

withdrawal means for withdrawing lean adsorbent from a the bottom of the regeneration column;

a reboiler for heating at least a part of the withdrawn absorbent to produce steam that is reintroduced into the regeneration column;

a first lean absorbent line for leading a second portion of the lean absorbent from the withdrawal means to a flashing means;

a steam withdrawal line for withdrawing the gaseous phase from the flashing means;

compression means for compressing the gaseous phase in line;

a line for injecting the compressed gaseous phase into the regeneration column;

a second lean absorbent line for withdrawing the liquid phase from the flashing means for returning the lean absorbent to an absorption device;

a gas withdrawal line for withdrawal of CO₂ and vapour from a top of the regeneration column;

separation means for separating the gas withdrawn from the top of the regeneration column in a CO₂ stream that is exported from the regenerator and water that is recycled to the regeneration column;

a reclaimer line for withdrawal of a portion of the lean absorbent and introduction of the lean absorbent into a reclaimer;

heating means for heating the lean absorbent in the reclaimer;

a reclaimer withdrawal line for withdrawing a gaseous phase generated in the reclaimer and introducing said gaseous phase into the compressing means; and

an amine waste line for withdrawing waste amine from the reclaimer for deposition.

7. The regenerator of claim 6, wherein a compressor is provided in the reclaimer withdrawal line for further reduction of the pressure in the reclaimer.