Stoichiometric combustion with exhaust gas recirculation and direct contact cooler

Patent metadata

Field	Value
Publication number	US-9732673-B2
Application number	US-201113702539-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 low emission power generation in hydrocarbon recovery processes are provided. One system includes a gas turbine system configured to stoichiometrically combust a compressed oxidant and a fuel in the presence of a compressed recycle exhaust gas and expand the discharge in an expander to generate a gaseous exhaust stream and drive a main compressor. A boost compressor can receive and increase the pressure of the gaseous exhaust stream and inject it into an evaporative cooling tower configured to use an exhaust nitrogen gas having a low relative humidity as an evaporative cooling media. The cooled gaseous exhaust stream is then compressed and recirculated through the system as a diluent to moderate the temperature of the stoichiometric combustion.

First claim

What is claimed is:

1. An integrated system, comprising:
a gas turbine system having a combustion chamber configured to substantially stoichiometrically combust a separately injected compressed oxidant and a fuel in the presence of a compressed recycle exhaust gas, wherein a ratio of oxygen supplied in the oxidant to oxygen required for stoichiometric combustion is maintained from 0.95:1 to 1.05:1, and wherein the compressed recycle exhaust gas serves to moderate a temperature of combustion in the combustion chamber, and the combustion chamber directs a discharge to an expander configured to generate a gaseous exhaust stream and at least partially drive a main compressor;
an exhaust gas recirculation system configured to recirculate at least a portion of the gaseous exhaust stream to the gas turbine system and having at least one integrated cooling unit, wherein the at least one integrated cooling unit cools the recirculated gaseous exhaust stream before injection into the main compressor to generate the compressed recycle exhaust gas; and
a CO 2 separator fluidly coupled to the compressed recycle exhaust gas via a purge stream and configured to discharge a residual stream consisting primarily of nitrogen gas to be expanded in a gas expander and generate a nitrogen exhaust gas, wherein the nitrogen exhaust gas is injected into the at least one integrated cooling unit;
wherein the at least one integrated cooling unit comprises a first column configured to receive the nitrogen exhaust gas and a cooling water supply and use the nitrogen exhaust gas to evaporate a portion of the cooling water supply to cool a remaining portion of the cooling water supply and generate a cooled water discharge; and
wherein the at least one integrated cooling unit further comprises a second column configured to receive the cooled water discharge and the recirculated gaseous exhaust stream and use the cooled water discharge to cool the recirculated gaseous exhaust stream before injection into the main compressor.

2. The system of claim 1 , further comprising at least one additional cooling unit, wherein the additional cooling unit is fluidly coupled to the at least one integrated cooling unit, and wherein the additional cooling unit cools is configured to cool the gaseous exhaust stream to a temperature of 105° F. before injection into the integrated cooling unit.

3. The system of claim 1 , further comprising a residual cooling unit fluidly coupled to the residual stream and configured to reduce the temperature of the residual stream and extract condensed water therefrom.

4. The system of claim 1 , wherein the at least one integrated cooling unit reduces the temperature of the gaseous exhaust stream to below 100° F.

5. The system of claim 1 , wherein the cooled water discharge is pressurized with a pump before being introduced into the second column.

6. The system of claim 1 , wherein the second column is further configured to condense and extract an amount of water from the gaseous exhaust stream.

7. The system of claim 1 , further comprising a heat exchanger fluidly coupled to the purge stream and configured to reduce the temperature of the purge stream prior to being introduced into the CO 2 separator.

8. The system of claim 1 , further comprising a boost compressor adapted to increase the pressure of the gaseous exhaust stream to a pressure between 17 psia and 21 psia before injection into the main compressor.

9. A method of generating power, comprising:
substantially stoichiometrically combusting a separately injected compressed oxidant and a fuel in a combustion chamber and in the presence of a compressed recycle exhaust gas, wherein a ratio of oxygen supplied in the compressed oxidant to oxygen required for stoichiometric combustion is maintained from 0.95:1 to 1.05:1, thereby generating a discharge stream, wherein the compressed recycle exhaust gas acts as a diluent configured to moderate the temperature of the discharge stream;
expanding the discharge stream in an expander to at least partially drive a main compressor and generate a gaseous exhaust stream;
directing the gaseous exhaust stream into at least one integrated cooling unit;
receiving a nitrogen exhaust gas and a cooling water supply in a first column of the at least one integrated cooling unit;
using the nitrogen exhaust gas to evaporate a portion of the cooling water supply, thereby cooling a remaining portion of the cooling water supply and generating a cooled water discharge;
receiving the cooled water discharge and the gaseous exhaust stream in a second column of the at least one integrated cooling unit;
using the cooled water discharge to cool the gaseous exhaust stream before injecting the gaseous exhaust stream into the main compressor to generate the compressed recycle exhaust gas;
directing a portion of the compressed recycle exhaust gas to a CO 2 separator via a purge stream, the CO 2 separator being configured to discharge a residual stream consisting primarily of nitrogen gas to be expanded in a gas expander and generate the nitrogen exhaust gas;
injecting the nitrogen exhaust gas into the at least one integrated cooling unit.

10. The method of claim 9 , further comprising cooling the gaseous exhaust stream in at least one pre-cooling unit disposed before a final integrated cooling unit to a temperature of 105° F., wherein the at least one pre-cooling unit is fluidly coupled to the final integrated cooling unit.

11. The method of claim 9 , further comprising:
cooling the residual stream with a residual cooling unit fluidly coupled to the CO 2 separator; and
extracting condensed water from the residual stream.

12. The method of claim 11 , further comprising: cooling the gaseous exhaust stream to a temperature below 100° F. with the cooled water discharge.

13. The method of claim 9 , further comprising pressurizing the cooled water discharge with a pump before being introduced into the second column.

14. The method of claim 9 , further comprising condensing and extracting an amount of water from the gaseous exhaust stream in the second column.

15. The method of claim 9 , further comprising reducing the temperature of the purge stream in a heat exchanger fluidly coupled to the purge stream and configured to reduce the temperature of the purge stream prior to being introduced into the CO 2 separator.

16. A combined-cycle power generation system, comprising:
a combustion chamber configured to substantially stoichiometrically combust a separately injected compressed oxidant and a fuel in the presence of a compressed recycle exhaust gas, wherein a ratio of oxygen supplied in the oxidant to oxygen required for stoichiometric combustion is maintained from 0.95:1 to 1.05:1, and wherein the combustion chamber directs a discharge to an expander configured to generate a gaseous exhaust stream and drive a main compressor;
an evaporative cooling tower having a first column and a second column; and
a CO 2 separator fluidly coupled to the compressed recycle exhaust gas via a purge stream and configured to discharge a residual stream consisting primarily of nitrogen gas to be expanded in a gas expander and generate a nitrogen exhaust gas,
wherein the first column is configured to receive the nitrogen exhaust gas and a cooling water supply and use the nitrogen exhaust gas to evaporate a portion of the cooling water supply to cool a remaining portion of the cooling water supply and generate a cooled water discharge, and
wherein the second column is configured to receive the cooled water discharge and the gaseous exhaust stream and use the c

Assignees

• Denton Robert D
• Gupta Himanshu
• Huntington Richard
• Minta Moses
• Mittricker Franklin F
• Starcher Loren K
• Exxonmobil Upstream Res Co

Inventors

• Denton Robert D
• Gupta Himanshu
• Huntington Richard
• Minta Moses
• Mittricker Franklin F
• Starcher Loren K

Classifications

• Y02E20/16

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

• F02C6/18

  using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants (using waste heat as source of energy for refrigeration plants F25B27/02; using the waste heat of a gasturbine for steam generation or in a steam cycle see F01K23/10) · CPC title

• Y02E20/12

  Heat utilisation in combustion or incineration of waste · CPC title

• F02C3/34 Primary

  with recycling of part of the working fluid, i.e. semi-closed cycles with combustion products in the closed part of the cycle · CPC title

• F02B47/10

  Circulation of exhaust gas in closed or semi-closed circuits, e.g. with simultaneous addition of oxygen · CPC title