Method and system for reducing energy requirements of a CO 2 capture system

• US 8,728,209 B2
• Filed: 08/02/2011
• Issued: 05/20/2014
• Est. Priority Date: 09/13/2010
• Status: Active Grant

• Current Assignee: General Electric Technology GmbH (GE Vernova, Inc.)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Naumovitz, Joseph P., Koch, Michael
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): PATEL, PANKTI R
• Application Number:
  US13/196,172
• Publication Number:
  US 20120060689A1
• Time in Patent Office: 1,022 Days
• Field of Search: None
• US Class Current: 95/173
• CPC Class Codes: B01D 2252/102 Ammonia
• CPC Class Codes: B01D 2252/204 Amines
• CPC Class Codes: B01D 2252/30 Ionic liquids and zwitter-ions
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 2259/65 Employing advanced heat integration, e.g. Pinch technology
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A method for reducing energy requirements of a CO₂ capture system comprises: contacting a flue gas stream with a CO₂ lean absorbent stream in an absorber, thereby removing CO₂ from the flue gas and providing a CO₂ rich absorbent stream; heating a first portion of the CO₂ rich absorbent stream using heat from the CO₂ lean absorbent stream, and providing the heated first portion of the CO₂ rich absorbent stream to a regenerator; providing a second portion of the CO₂ rich absorbent stream to the regenerator, wherein the heated first portion is hotter than the second portion and the heated first portion is provided to the regenerator at a lower elevation in the regenerator relative to that of the second portion.

Claims

1. A method for reducing energy requirements of a CO₂ capture system, the method comprising:

contacting a flue gas stream with a CO₂ lean absorbent stream in an absorber, thereby removing CO₂ from the flue gas and providing a CO₂ rich absorbent stream;

heating a first portion of the CO₂ rich absorbent stream using heat from the CO₂ lean absorbent stream, and providing the heated first portion of the CO₂ rich absorbent stream to a regenerator;

providing a second portion of the CO₂ rich absorbent stream to the regenerator, wherein the heated first portion is hotter than the second portion and the heated first portion is provided to the regenerator at a lower elevation in the regenerator relative to that of the second portion;

separating a gaseous CO₂ from the heated first portion prior to providing the heated first portion to the regenerator; and

compressing the gaseous CO₂ and providing the compressed gaseous CO₂ to the regenerator at a lower elevation in the regenerator relative to that of the liquid portion.

2. The method of claim 1, further comprising:

after separating the gaseous CO₂ from the heated first portion and prior to providing the first portion to the regenerator, further heating the first portion using heat from the CO₂ lean absorbent stream.

3. The method of claim 1, further comprising:

washing residual absorbent from the flue gas stream leaving the absorber;

stripping CO₂ from the residual absorbent to provide overhead CO₂ vapors; and

combining overhead CO₂ vapors with the gaseous CO₂ prior to compressing the gaseous CO₂.

4. A system for reducing energy requirements of a CO₂ capture system, the system comprising:

an absorber vessel to contact a gas stream, having CO₂, with a CO₂ lean absorbent stream therein, thereby removing CO₂ from the gas stream and providing a CO₂ rich absorbent stream;

a heat exchanger to heat a first portion of the CO₂ rich absorbent stream using heat from the CO₂ lean absorbent stream,

a regeneration vessel that receives the heated first portion of the CO₂ rich absorbent stream, and a second portion of the CO₂ rich absorbent stream which is cooler than the heated first portion;

a gas/liquid separator to separate a gaseous CO₂ from the liquid portion of the heated first portion prior to providing the heated first portion to the regeneration vessel; and

a compressor to compress the separated gaseous CO₂ from the heated first portion;

wherein the compressed gaseous CO₂ is provided to the regeneration vessel at a lower elevation in the regeneration vessel relative to the separated liquid portion of the heated first portion, and the separated liquid portion of the heated first portion is provided at a lower elevation in the regeneration vessel relative to the second portion.

5. The system of claim 4, further comprising:

a second heat exchanger to heat the liquid portion of the heated first portion prior to being provided to the regeneration vessel.

6. The system of claim 4, further comprising:

a wash vessel to wash residual absorbent from the gas stream leaving the absorber vessel; and

a stripping column to strip CO₂ from the residual absorbent to provide overhead CO₂ vapors;

wherein the overhead CO₂ vapors are combined with the gaseous CO₂ prior to compressing the gaseous CO₂.