Method and system for reducing energy requirements of a CO

1. A method for reducing energy requirements of a CO 2 capture system, the method comprising:

contacting a flue gas stream with a CO 2 lean absorbent stream in an absorber, thereby removing CO 2 from the flue gas and providing a CO 2 rich absorbent stream;

heating a first portion of the CO 2 rich absorbent stream using heat from the CO 2 lean absorbent stream, and providing the heated first portion of the CO 2 rich absorbent stream to a regenerator;

providing a second portion of the CO 2 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 CO 2 from the heated first portion prior to providing the heated first portion to the regenerator; and

compressing the gaseous CO 2 and providing the compressed gaseous CO 2 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 CO 2 from the heated first portion and prior to providing the first portion to the regenerator, further heating the first portion using heat from the CO 2 lean absorbent stream.

3. The method of claim 1 , further comprising:

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

stripping CO 2 from the residual absorbent to provide overhead CO 2 vapors; and

combining overhead CO 2 vapors with the gaseous CO 2 prior to compressing the gaseous CO 2 .

4. A system for reducing energy requirements of a CO 2 capture system, the system comprising:

an absorber vessel to contact a gas stream, having CO 2 , with a CO 2 lean absorbent stream therein, thereby removing CO 2 from the gas stream and providing a CO 2 rich absorbent stream;

a heat exchanger to heat a first portion of the CO 2 rich absorbent stream using heat from the CO 2 lean absorbent stream,

a regeneration vessel that receives the heated first portion of the CO 2 rich absorbent stream, and a second portion of the CO 2 rich absorbent stream which is cooler than the heated first portion;

a gas/liquid separator to separate a gaseous CO 2 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 CO 2 from the heated first portion;

wherein the compressed gaseous CO 2 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 CO 2 from the residual absorbent to provide overhead CO 2 vapors;

wherein the overhead CO 2 vapors are combined with the gaseous CO 2 prior to compressing the gaseous CO 2 .