Low emission triple-cycle power generation and CO2 separation systems and methods

Patent metadata

Field	Value
Publication number	US-9903271-B2
Application number	US-201113702538-A
Country	US
Kind code	B2
Filing date	Jun 9, 2011
Priority date	Jul 2, 2010
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Methods and systems 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 C0 2 separator which discharges C0 2 and a nitrogen-rich gas which can be expanded in a gas expander to generate additional mechanical power.

First claim

What is claimed is:

1. An integrated system, comprising:
a gas turbine system having a first combustion chamber configured to substantially stoichiometrically combust a first compressed oxidant and a first fuel in the presence of a compressed recycle stream such that there is a ratio of oxygen supplied to oxygen required for stoichiometric combustion from 0.9:1 to 1.1:1, wherein the first combustion chamber directs a first discharge stream to an expander to generate a gaseous exhaust stream and at least partially drive a main compressor;
an exhaust gas recirculation system comprising at least one boost compressor configured to receive and boost the pressure of the gaseous exhaust stream before directing the gaseous exhaust stream into the main compressor, wherein the main compressor compresses the gaseous exhaust stream and thereby generates the compressed recycle stream, the compressed recycle stream acting as a first diluent to moderate the temperature of the first discharge stream;
a CO 2 separator fluidly coupled to the compressed recycle stream via a purge stream;
a second combustion chamber fluidly coupled to the CO 2 separator via a residual stream consisting primarily of nitrogen derived from the CO 2 separator, wherein the second combustion chamber is configured to substantially stoichiometrically combust a second fuel and a second compressed oxidant in the presence of the residual stream, the residual stream acting as a second diluent to moderate a temperature of combustion in the second combustion chamber, and wherein the first and second compressed oxidants and the first and second fuels are derived from same sources, respectively;
a heat exchanger fluidly coupled to both the purge stream and the residual stream and adapted to transfer heat from the purge stream to the residual stream prior to injection of the residual stream into the second combustion chamber; and
a gas expander fluidly coupled to the second combustion chamber via a second discharge stream.

2. The system of claim 1 , further comprising first and second cooling units fluidly coupled to the at least one boost compressor, the first cooling unit being configured to receive and cool the gaseous exhaust stream before introduction to the at least one boost compressor, and the second cooling unit being configured to receive the gaseous exhaust stream from the at least one boost compressor and further cool the gaseous exhaust stream to generate a cooled recycle gas.

3. The system of claim 1 , wherein the heat exchanger is configured to transfer heat from the purge stream to the residual stream through an intermediate material to reduce a temperature of the purge stream and simultaneously increase the temperature of the residual stream.

4. The system of claim 1 , further comprising a catalysis apparatus disposed in association with the purge stream, the catalysis apparatus being configured to increase a temperature of the purge stream prior to entering the heat exchanger.

5. The system of claim 1 , wherein the gas expander is configured to expand the second discharge stream and thereby generate mechanical power and an exhaust gas.

6. The system of claim 5 , further comprising an inlet compressor driven by the mechanical power generated by the gas expander, wherein the inlet compressor is configured to provide the first and second compressed oxidants.

7. A method of generating power, comprising:
stoichiometrically combusting a first compressed oxidant and a first fuel in a first combustion chamber and in the presence of a compressed recycle stream such that there is a ratio of oxygen supplied to oxygen required for stoichiometric combustion from 0.9:1 to 1.1:1, thereby generating a first discharge stream, wherein the compressed recycle stream acts as a first diluent to moderate a temperature of the first discharge stream;
expanding the first discharge stream in an expander to at least partially drive a first compressor and generate a gaseous exhaust stream;
directing the gaseous exhaust stream into the first compressor, wherein the first compressor compresses the gaseous exhaust stream and thereby generates the compressed recycle stream;
extracting a portion of the compressed recycle stream to a CO 2 separator via a purge stream, the CO 2 separator being fluidly coupled to a second combustion chamber via a residual stream derived from the CO 2 separator and consisting primarily of nitrogen;
using a heat exchanger fluidly coupled to both the purge stream and the residual stream to transfer heat from the purge stream to the residual stream to increase the temperature of the residual stream prior to injection of the residual stream into the second combustion chamber;
substantially stoichiometrically combusting a second compressed oxidant and a second fuel in the second combustion chamber in the presence of the residual stream to generate a second discharge stream, wherein the first and second compressed oxidants and the first and second fuels are derived from same sources, respectively;
moderating a temperature of combustion in the second combustion chamber with the residual stream discharged from the CO 2 separator acting as a second diluent;
expanding the second discharge stream in a gas expander; and
using at least one of a boost compressor and a first cooling unit adapted to increase the mass flow rate of the gaseous exhaust stream to generate recycle gas.

8. The method of claim 7 , comprising cooling the gaseous exhaust stream with the first cooling unit fluidly coupled to the at least one boost compressor, the first cooling unit being configured to receive and cool the gaseous exhaust stream before introduction to the at least one boost compressor.

9. The method of claim 8 , further comprising cooling the gaseous exhaust stream from the at least one boost compressor with a second cooling unit fluidly coupled to the at least one boost compressor to generate the recycle gas.

10. The method of claim 7 , further comprising driving an inlet compressor with the mechanical power generated by the gas expander, the inlet compressor being configured to generate the first and second compressed oxidants.

11. The method of claim 7 , wherein the heat exchanger is configured to transfer heat from the purge stream to the residual stream through an intermediate material to reduce a temperature of the purge stream and simultaneously increase the temperature of the residual stream.

12. The method of claim 11 , further comprising increasing the temperature of the purge stream by combusting oxygen and remaining fuel in a catalysis apparatus disposed within the purge stream prior to the heat exchanger.

13. An integrated system, comprising:
a first gas turbine system, comprising:
a first compressor configured to receive and compress a recycled exhaust gas and provide a first compressed recycle stream;
a first combustion chamber configured to receive the first compressed recycle stream, a first compressed oxidant, and a first fuel stream, the first combustion chamber being adapted to substantially stoichiometrically combust the first fuel stream and first compressed oxidant such that there is a ratio of oxygen supplied to oxygen required for stoichiometric combustion from 0.9:1 to 1.1:1, wherein the first compressed recycle stream serves as a first diluent to moderate combustion temperatures in the first combustion chamber;
a first expander coupled to the first compressor and configured to receive a first discharge from the first combustion chamber and generate the recycled exhaust gas and at least partially drive the first compressor; and
a boost compressor configured to increase the pressure o

Assignees

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

Inventors

• Oelfke Russell H
• Minta Moses

Classifications

• F05D2220/76

  an electrical generator · CPC title

• F02C3/34

  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

• Y02E20/16

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

• F05D2270/08

  to produce clean exhaust gases · CPC title

• F05D2260/61

  Removal of CO2 · CPC title