Low emission power generation systems and methods

Patent metadata

Field	Value
Publication number	US-9732675-B2
Application number	US-201113702541-A
Country	US
Kind code	B2
Filing date	Jun 9, 2011
Priority date	Jul 2, 2010
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Methods and systems for CO 2 separation for low emission power generation in combined-cycle power plants are provided. One system includes a gas turbine system that stoichiometrically combusts a fuel and an oxidant in the presence of a compressed recycle stream to provide mechanical power and a gaseous exhaust. The compressed recycle stream acts as a diluent to moderate the temperature of the combustion process. A boost compressor can boost the pressure of the gaseous exhaust before being compressed into the compressed recycle stream. A purge stream is tapped off from the compressed recycle stream and directed to a CO 2 separator configured to absorb CO 2 from the purge stream using a potassium carbonate solvent.

First claim

What is claimed is:

1. An integrated CO 2 separation system, comprising:
a gas turbine system having a combustion chamber configured to substantially stoichiometrically combust a compressed oxidant and a fuel, where the compressed oxidant is air, oxygen-rich air, oxygen-depleted air, or combinations thereof;
a combustion temperature control system configured to inject at least a portion of a compressed recycle stream into the combustion chamber to generate a discharge stream and to act as a diluent to control the temperature of the discharge stream, wherein the compressed recycle stream is injected into the combustion chamber independent of the compressed oxidant;
an expander configured to expand the discharge stream to generate a gaseous exhaust stream and at least partially drive a main compressor;
an exhaust gas recirculation system having a boost compressor and one or more cooling units configured to provide a cooled recycle gas having a water component and a gaseous component to the main compressor, wherein the main compressor (i) receives substantially all of the gaseous component of the cooled recycle gas that passes through the boost compressor and (ii) compresses the cooled recycle gas and generates the compressed recycle stream, a portion of which is directed to the combustion chamber and a portion of which provides a purge stream; and
a CO 2 separator fluidly coupled to the purge stream, the CO 2 separator comprising:
an absorber column configured to receive the purge stream and circulate a potassium carbonate solvent therein to absorb CO 2 in the purge stream, wherein the absorber column discharges a nitrogen-rich residual stream and a bicarbonate solvent solution;
a first valve fluidly coupled to the absorber column and configured to flash the bicarbonate solvent solution to a lower pressure, thereby generating a reduced-pressure solution;
a separator fluidly coupled to the first valve and configured to receive the reduced-pressure solution and remove a first portion of CO 2 therefrom;
a second valve fluidly coupled to the separator and configured to receive a remaining portion of the reduced-pressure solution and flash the remaining portion to a near-atmospheric pressure, thereby generating a near-atmospheric bicarbonate solvent solution;
a regeneration column fluidly coupled to the second valve and configured to receive and boil the near-atmospheric bicarbonate solvent solution to remove a CO 2 and water mixture therefrom, thereby producing a regenerated potassium carbonate solvent to be recirculated back to the absorber column; and
a condenser fluidly coupled to the regeneration column and configured to receive and separate a second portion of CO 2 from the CO 2 and water mixture removed from the near-atmospheric bicarbonate solvent solution;

wherein the pressure of the first portion of CO 2 is higher than the pressure of the second portion of CO 2 and the first portion and the second portion of CO 2 are separately directed to a downstream compression system.

2. The system of claim 1 , wherein the temperature of the purge stream is about 800° F., and the pressure of the purge stream is about 280 psia.

3. The system of claim 2 , further comprising a heat exchanger associated with the purge stream, wherein the heat exchanger is a cross-exchange heat exchanger configured to reduce the temperature of the purge stream to between 250° F. and 300° F.

4. The system of claim 1 , wherein the regeneration column operates at a pressure of about 3 psig.

5. The system of claim 1 , further comprising a reboiler fluidly coupled to the regeneration column and configured to receive and heat a portion of the regenerated potassium carbonate solvent and produce a heated regenerated potassium carbonate solvent.

6. The system of claim 5 , wherein the reboiler is configured to recirculate the heated regenerated potassium carbonate solvent back into the regeneration column to produce steam for boiling the bicarbonate solvent solution.

7. The system of claim 1 , wherein the second portion of CO 2 is directed to a first stage of the downstream compression system and the first portion of CO 2 is directed to an intermediate stage of the downstream compression system.

8. The system of claim 1 , wherein a portion of the water separated from the CO 2 and water mixture is pumped back into the regeneration column to create steam.

9. The system of claim 1 , wherein a portion of the bicarbonate solvent solution is withdrawn from the regeneration column prior to complete solvent regeneration, and recirculated and fed low into the absorber column.

10. The system of claim 9 , wherein 50% or more of a total amount of bicarbonate solvent solution is withdrawn from the regeneration column prior to complete solvent regeneration.

11. An integrated CO 2 separation system, comprising:
a gas turbine system having a combustion chamber configured to substantially stoichiometrically combust a compressed oxidant and a fuel, where the compressed oxidant is air, oxygen-rich air, oxygen-depleted air, or combinations thereof;
a combustion temperature control system configured to inject at least a portion of a compressed recycle stream into the combustion chamber to generate a discharge stream in order to expand the discharge stream in an expander, thereby generating a gaseous exhaust stream and at least partially driving a main compressor, wherein the compressed recycle stream acts as a diluent configured to moderate the temperature of the discharge stream, and wherein the compressed recycle stream is injected into the combustion chamber independent of the compressed oxidant;
at least one oxygen sensor disposed on one of an outlet or an inlet of the expander or on an outlet of the combustion chamber and operatively connected to a flow control system, wherein the at least one oxygen sensor determines a preferred amount of the oxidant to be injected into the combustion chamber by the flow control system;
an exhaust gas recirculation system having a boost compressor and one or more cooling units fluidly coupled to the boost compressor, the boost compressor being configured to receive and boost the pressure of the gaseous exhaust stream having a gaseous component and a water component and the one or more cooling units being configured to cool the gaseous exhaust stream and provide a cooled recycle gas to the main compressor, wherein the main compressor receives substantially all of the gaseous component of the cooled recycle gas that passes through the boost compressor, compresses the cooled recycle gas and generates the compressed recycle stream;
a purge stream fluidly coupled to the compressed recycle stream and having a heat exchanger configured to reduce the temperature of the purge stream and generate a cooled purge stream; and
a CO 2 separator fluidly coupled to the heat exchanger, the CO 2 separator comprising:
an absorber column configured to receive the cooled purge stream and circulate a potassium carbonate solvent therein to absorb CO 2 in the cooled purge stream, wherein the absorber column discharges a nitrogen-rich residual stream and a bicarbonate solvent solution;
a first valve fluidly coupled to the absorber column and configured to flash the bicarbonate solvent solution to a lower pressure, thereby generating a reduced-pressure solution;
a separator fluidly coupled to the first valve and configured to receive the reduced-pressure solution and remove a first portion of CO 2 therefrom to be injected into an inner stage of a downstream compression system;
a second valve fluidly coupled to the separator and configured to receive remaining portions of the reduced-pressure solution and flash the re

Assignees

• Oelfke Russell H
• Minta Moses
• Exxonmobil Upstream Res Co

Inventors

• Oelfke Russell H
• Minta Moses

Classifications

• Y02E20/16

  Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] · CPC title

• F05D2260/61

  Removal of CO2 · CPC title

• F02C6/10 Primary

  supplying working fluid to a user, e.g. a chemical process, which returns working fluid to a turbine of the plant · CPC title

• F02C7/22 Primary

  Fuel supply systems · CPC title

• F02C7/143

  before or between the compressor stages · CPC title