A method is provided for operating a combined cycle power plant including a CO2 capture system and flue gas recirculation system. The method includes controlling a flue gas recirculation rate and a re-cooling temperature of the recirculated flue gases, depending on load, to optimize the overall plan
A method is provided for operating a combined cycle power plant including a CO2 capture system and flue gas recirculation system. The method includes controlling a flue gas recirculation rate and a re-cooling temperature of the recirculated flue gases, depending on load, to optimize the overall plant efficiency including the CO2 capture system. Also provided is a combined cycle power plant including a CO2 capture system and flue gas recirculation system. The plant being configured to carry out a method in which a flue gas recirculation rate and a re-cooling temperature of recirculated flue gases is controlled depending on load to optimize the overall plant efficiency including the CO2 capture system.
대표청구항▼
1. A method for operating a combined cycle power plant comprising at least one gas turbine and a heat recovery steam generator with a CO2 capture system and flue gas recirculation system comprising a flue gas duct, which directs a first partial flow of flue gases from the heat recovery steam generat
1. A method for operating a combined cycle power plant comprising at least one gas turbine and a heat recovery steam generator with a CO2 capture system and flue gas recirculation system comprising a flue gas duct, which directs a first partial flow of flue gases from the heat recovery steam generator to an inlet gas flow of the at least one gas turbine, at least one control body to control a recirculation ratio, a re-cooler with temperature control to cool recirculation flue gases, at least one CO2 and/or oxygen concentration measurement device, wherein the first partial flow, which is recirculated, is cooled by a recirculation flue gas re-cooler before mixing with ambient air for reintroduction into a compressor of the gas turbine, and a second partial flow is directed via the CO2 capture system to a stack for release to the environment, the method comprising: controlling a flue gas recirculation rate and a re-cooling temperature of the recirculated flue gases, depending on load, to optimize the overall plant efficiency including the CO2 capture system wherein flue gas recirculation rate at base load equals a recirculation rate for best CO2 capture efficiency of the CO2 capture system and is reduced below a recirculation rate for best CO2 capture efficiency of the CO2 capture system at a load below base load, and wherein at part load the re-cooling temperature is increased over a base load re-cooling temperature. 2. The method according to claim 1, wherein oxygen or oxygen enriched air is admixed to the inlet gases of the gas turbine compressor of the combined cycle power plant to allow a higher flue gas recirculation rate. 3. The method according to claim 2, wherein a minimum normalized oxygen concentration in inlet air is given as a function of relative load of the combined cycle power plant and the normalized oxygen concentration in the inlet air is controlled by variation of the recirculation rate and/or admixing of oxygen or oxygen enriched air. 4. The method according to claim 2, wherein the recirculation rate is a highest possible recirculation rate given that the normalized oxygen concentration in the inlet air remains sufficient to assure complete combustion with low CO and unburned hydrocarbon emissions. 5. The method according to claim 2, wherein the recirculation rate and/or admixing of oxygen or oxygen enriched air is adjusted as a function of measured CO and/or unburned hydrocarbon emissions. 6. The method according to claim 2, wherein the recirculation rate and/or admixing of oxygen or oxygen enriched air is adjusted as a function of measured combustor pulsations. 7. The method according to claim 1, wherein the recirculation rate is kept above a minimum value to assure a required minimum flow through the CO2 capture system. 8. The method according to claim 1, wherein the re-cooling temperature is controlled as a function of relative load. 9. The method according to claim 1, wherein the re-cooling temperature is controlled as a function of relative load and the recirculation rate. 10. The method according to claim 1, wherein a target compressor inlet temperature of the gas turbine is a function of relative load and is controlled by a combination of controlling the re-cooling temperature and the recirculation rate. 11. The method according to claim 1, wherein the recirculation rate is controlled with the help of a variable speed flue gas blower for recirculation and/or with the help of a variable speed flue gas blower to CO2 capture system for the flue gases directed to the CO2 capture system. 12. The method according to claim 1, wherein a flue gas blower for recirculation and/or flue gas blower to CO2 capture system is used to enhance a purge operation. 13. The method according to claim 1, wherein the re-cooling temperature can be increased at part load relative to the base load re-cooling temperature to realize a higher gas turbine compressor inlet temperature at part load. 14. The method according to claim 1, wherein the recirculation rate has a first maximum above 80% relative load, has a lower value than said first maximum at 50% relative load and a second maximum value below 50% relative load. 15. The method according to claim 1, wherein at part load operation, the recirculation rate is below the recirculation rate for best CO2 capture efficiency of the CO2 capture system. 16. A combined cycle power plant comprising at least one gas turbine, a heat recovery steam generator with a CO2 capture system and flue gas recirculation system having a flue gas duct, which directs a first partial flow of the flue gases from the heat recovery steam generator to an inlet gas flow of a gas turbine, at least one control body to control the recirculation ratio, a re-cooler with temperature control to cool recirculation flue gases, at least one CO2 and/or oxygen concentration measurement device, the combined cycle power plant configured to control a flue gas recirculation rate and a re-cooling temperature of the recirculated flue gases depending on load to optimize overall plant efficiency including the CO2 capture system, wherein a flue gas recirculation rate at base load equals a recirculation rate for best CO2 capture efficiency of the CO2 capture system and is reduced below a recirculation rate for best CO2 capture efficiency of the CO2 capture system at a load below base load, and wherein at part load the re-cooling temperature is increased over a base load re-cooling temperature. 17. The power plant according to claim 16, further comprising CO and/or unburned hydrocarbon measurement device downstream of the gas turbine. 18. The power plant according to claim 16, further comprising a variable speed flue gas blower for recirculation and/or a variable speed flue gas blower to CO2 capture system for the flue gases directed to the CO2 capture system for control of the recirculation rate. 19. The power plant according to claim 16, further comprising an air separation unit for admixing oxygen or oxygen enriched air (34) to inlet gases of the compressor.
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이 특허에 인용된 특허 (4)
Kataoka Masaki,JPX ; Utamura Motoaki,JPX ; Kuwahara Takaaki,JPX, Exhaust gas recirculation type combined plant.
Liu, Kunlei; Frimpong, Reynolds A.; Liu, Kun, Hybrid process using a membrane to enrich flue gas CO2 with a solvent-based post-combustion CO2 capture system.
Hellat, Jaan; Benz, Eribert; Graf, Frank; Wind, Torsten; Guethe, Felix; Doebbeling, Klaus, Method of operating a gas turbine power plant with exhaust gas recirculation and corresponding gas turbine power plant.
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