CA2527948A1 - Method for obtaining ultra-low nox emissions from gas turbines operating at high turbine inlet temperatures - Google Patents
Method for obtaining ultra-low nox emissions from gas turbines operating at high turbine inlet temperatures Download PDFInfo
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- CA2527948A1 CA2527948A1 CA002527948A CA2527948A CA2527948A1 CA 2527948 A1 CA2527948 A1 CA 2527948A1 CA 002527948 A CA002527948 A CA 002527948A CA 2527948 A CA2527948 A CA 2527948A CA 2527948 A1 CA2527948 A1 CA 2527948A1
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- air
- fuel
- combustor
- combustion
- gas turbine
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000002485 combustion reaction Methods 0.000 claims abstract description 32
- 239000000446 fuel Substances 0.000 claims abstract description 25
- 239000000203 mixture Substances 0.000 claims abstract description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000001301 oxygen Substances 0.000 claims abstract description 13
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 13
- 239000000567 combustion gas Substances 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 43
- 239000003570 air Substances 0.000 claims description 38
- 239000012080 ambient air Substances 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 230000003197 catalytic effect Effects 0.000 claims description 3
- 238000011084 recovery Methods 0.000 description 4
- 239000005431 greenhouse gas Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
- F02C3/34—Gas-turbine plants characterised by the use of combustion products as the working fluid with recycling of part of the working fluid, i.e. semi-closed cycles with combustion products in the closed part of the cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
- F02C3/20—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products
- F02C3/22—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products the fuel or oxidant being gaseous at standard temperature and pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C6/00—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use
- F02C6/18—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C9/00—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
- F23C9/08—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber for reducing temperature in combustion chamber, e.g. for protecting walls of combustion chamber
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/40—Continuous combustion chambers using liquid or gaseous fuel characterised by the use of catalytic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2270/00—Control
- F05D2270/01—Purpose of the control system
- F05D2270/08—Purpose of the control system to produce clean exhaust gases
- F05D2270/082—Purpose of the control system to produce clean exhaust gases with as little NOx as possible
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2202/00—Fluegas recirculation
- F23C2202/30—Premixing fluegas with combustion air
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Chemical Kinetics & Catalysis (AREA)
Abstract
A method of combustion comprising providing fuel (13) to a turbine combustor (14), supplying air (21) to form a fuel/air mixture having an equivalence ratio greater than 0.55 supplying cooled combustion gases (37) and mixing with the air such that the mixture oxygen is less than 18 %, and supplying the mixture to the combustor (14).
Description
DATE OF DEPOSIT
I HEREBY CERTIFY THIS CORRESPONDENCE IS BEING
DEPOSITED WITH THE UNTTED STATES POSTAL SERVICE
IN AN ENVELpPE ADDRESSED TO THE COMMISSIONER
FOR PATENTS, MAIL STOP PATENT APPLICATION, PO
BOX 1450, ALEXANDRIA, VA 22313-1450 AS "EXPRESS
MAIL POST OFFICE TO ADDRESSEE".
Robert L. Rispoli TYPED N F PERSON IVIAILIN APER
METHOD FOR OBTA~ING ULTRA-LOW NOx EMISSIONS FROM GAS
TURBINES OPERATING AT HIGH TURBINE INLET TEMPERATURES
BACKGROUND OF THE INVENTION
Field of tile Invention [0001] The present invention relates to a method for improving the thermal efficiency of gas turbine systems by enabling higher firing temperatures without unacceptable NOx production. In particular, the present invention is a method for obtaining low, single-digit NOx emission levels from high turbine~inlet-temperature gas turbines. More particularly, in combined cycle gas turbine systems, the present invention is directed to a method that enables use of higher pressure ratio, higher efficiency gas turbines without sacrificing steam cycle performance thereby providing increased system efficiency.
Description of the Related Art [0002] With the present awareness of the importance of improving the efficiency of gas turbine systems in order to reduce fuel costs and also to reduce the emissions of greenhouse gases, there has been a continuing trend to operate such systems at higher turbine inlet temperatures. This results in combustor exit temperatures are exceedingly higher such that a limit is placed on achievable NOx emission levels at the required combustor residence times. Thus, essentially all gas turbine systems typically operating with a turbine inlet temperature greater than about 2200°F, known in the art as "F-Class"
machines, even those with dry low NOx combustion systems, now require efficiency robbing after-treatment to achieve NOx emissions less than about 3ppm. With emissions levels of 2ppm or lower increasingly being required, there is a disconnect between the need for lower NOx emissions and the need for reduced emissions of greenhouse gases.
I HEREBY CERTIFY THIS CORRESPONDENCE IS BEING
DEPOSITED WITH THE UNTTED STATES POSTAL SERVICE
IN AN ENVELpPE ADDRESSED TO THE COMMISSIONER
FOR PATENTS, MAIL STOP PATENT APPLICATION, PO
BOX 1450, ALEXANDRIA, VA 22313-1450 AS "EXPRESS
MAIL POST OFFICE TO ADDRESSEE".
Robert L. Rispoli TYPED N F PERSON IVIAILIN APER
METHOD FOR OBTA~ING ULTRA-LOW NOx EMISSIONS FROM GAS
TURBINES OPERATING AT HIGH TURBINE INLET TEMPERATURES
BACKGROUND OF THE INVENTION
Field of tile Invention [0001] The present invention relates to a method for improving the thermal efficiency of gas turbine systems by enabling higher firing temperatures without unacceptable NOx production. In particular, the present invention is a method for obtaining low, single-digit NOx emission levels from high turbine~inlet-temperature gas turbines. More particularly, in combined cycle gas turbine systems, the present invention is directed to a method that enables use of higher pressure ratio, higher efficiency gas turbines without sacrificing steam cycle performance thereby providing increased system efficiency.
Description of the Related Art [0002] With the present awareness of the importance of improving the efficiency of gas turbine systems in order to reduce fuel costs and also to reduce the emissions of greenhouse gases, there has been a continuing trend to operate such systems at higher turbine inlet temperatures. This results in combustor exit temperatures are exceedingly higher such that a limit is placed on achievable NOx emission levels at the required combustor residence times. Thus, essentially all gas turbine systems typically operating with a turbine inlet temperature greater than about 2200°F, known in the art as "F-Class"
machines, even those with dry low NOx combustion systems, now require efficiency robbing after-treatment to achieve NOx emissions less than about 3ppm. With emissions levels of 2ppm or lower increasingly being required, there is a disconnect between the need for lower NOx emissions and the need for reduced emissions of greenhouse gases.
[0003] It is well known in the art that combined cycle gas turbine-steam turbine systems yield higher efficiencies than either simple cycle gas turbines or stand alone steam turbine power plants, particularly when such combined cycle systems operate with gas turbines exhaust gas temperatures of at least about 1000°F, more typically 1100°F.
Use of higher efficiency gas turbines having pressure ratios much greater than 20/1 is usually disadvantageous without increases in turbine inlet temperature to maintain a sufficiently high exhaust temperature. There is therefore a need for gas turbine combustion systems capable of achieving ultra low NOx emissions at the higher required combustor outlet temperatures. Further, because the efficiency of typical high performance gas turbines is reduced at ambient temperatures below the design point, there is a need for a method to allow for improved efficiency at low ambient temperatures.
Use of higher efficiency gas turbines having pressure ratios much greater than 20/1 is usually disadvantageous without increases in turbine inlet temperature to maintain a sufficiently high exhaust temperature. There is therefore a need for gas turbine combustion systems capable of achieving ultra low NOx emissions at the higher required combustor outlet temperatures. Further, because the efficiency of typical high performance gas turbines is reduced at ambient temperatures below the design point, there is a need for a method to allow for improved efficiency at low ambient temperatures.
[0004] It has now been found that NOx emissions well below 3ppm can be achieved even at combustion temperatures above those required for the highest inlet temperature gas turbines now available. By mixing cooled turbine exhaust gases with fresh air, inlet air comprising reduced oxygen content is supplied to the turbine compressor. Advantageously, the temperature of the air supplied to the compressor may be controlled to a predetermined value regardless of how low the ambient air temperature may be, thus allowing the turbine to be operated at maximum efficiency regardless of ambient conditions. If maximum power is required, the inlet air temperature can be reduced at some sacrifice in efficiency.
1?ESCRIPTION OF THE INVENTION
(0005] The present invention is a method and an apparatus for achieving ultra-low NOx combustion emissions, even at the highest combustion temperature required for present gas turbines, comprising the use of exhaust gas recirculation (EGR).
(4006] In the present invention the term "air" refers to a gas that contains the oxidizer oxygen. For clarity of the presentation of the invention, the more conventional fuel/air terminology ("fuel/air mixture") will be used, but the invention should not be considered so limited.
[0007] The term "equivalence ratio" is used to denote the proportions of fuel and air in the fuel/air mixture. The equivalence ratio is the ratio of the actual fuel/air ratio to the stoichiometric fuel/air ratio, where the stoichiometric co~f~cients are calculated for the reaction giving full oxidation products C02 and HaO. An equivalence ratio greater than 1.0 defines a fuel-rich fuel/air mixture, and an equivalence ratio less than 1.0 defines a fuel-lean fuel/air mixture.
[0008] As recognized in the art, hydrocarbon fuels have a limited range of fuel/air ratios within which a flame can propagate. The rich flammability limit for combustion is the highest equivalence ratio for flame combustion, and similarly the lean flammability limit is the lowest. As is known, these limits typically widen with an increase in fuellair mixture temperature or pressure and narrow with reduction in oxygen concentration.
Catalytic combustion, as for example using the method of U.S. Patent No.
(0005] The present invention is a method and an apparatus for achieving ultra-low NOx combustion emissions, even at the highest combustion temperature required for present gas turbines, comprising the use of exhaust gas recirculation (EGR).
(4006] In the present invention the term "air" refers to a gas that contains the oxidizer oxygen. For clarity of the presentation of the invention, the more conventional fuel/air terminology ("fuel/air mixture") will be used, but the invention should not be considered so limited.
[0007] The term "equivalence ratio" is used to denote the proportions of fuel and air in the fuel/air mixture. The equivalence ratio is the ratio of the actual fuel/air ratio to the stoichiometric fuel/air ratio, where the stoichiometric co~f~cients are calculated for the reaction giving full oxidation products C02 and HaO. An equivalence ratio greater than 1.0 defines a fuel-rich fuel/air mixture, and an equivalence ratio less than 1.0 defines a fuel-lean fuel/air mixture.
[0008] As recognized in the art, hydrocarbon fuels have a limited range of fuel/air ratios within which a flame can propagate. The rich flammability limit for combustion is the highest equivalence ratio for flame combustion, and similarly the lean flammability limit is the lowest. As is known, these limits typically widen with an increase in fuellair mixture temperature or pressure and narrow with reduction in oxygen concentration.
Catalytic combustion, as for example using the method of U.S. Patent No.
6,358,040, unlike conventional flame combustion, is not limited to equivalence ratios within the normal flammability limits of flame combustion and thus is preferred in the method of the present invention.
[0009] In the present invention, fresh inlet air is mixed with cooled combustion gases in sufficient quantity to reduce the oxygen content of the resulting mixture, preferably to at least eighteen mole percent, more preferably about fifteen mole percent or lower. Sufficient oxygen must be present to achieve a mixture with fuel, at the combustor inlet temperature, having the required flame temperature.
Advantageously, the combustion products may contain less than one percent residual oxygen. In order to achieve complete combustion of fuel, it is preferred that the combustion comprises a fuel-lean ratio having an equivalence ratio greater than about 0.55 and more preferably greater than about 0.6.
[0010] In a preferred method of the present invention, the inlet air is minced with cooled combustion product gas prior to entering the compressor of a gas turbine.
Optionally, the cooled combustion gases may be compressed separately and then mixed with compressed air exiting the gas turbine compressor. After compression, the compressed air mixture is mixed with fuel and combusted thereby producing hot combustion products that are expanded in the turbine to produce power and hot exhaust gas. The exhaust gas is then transported into a heat recovery unit. Typically, the heat recovery unit comprises a steam boiler in which case the steam may be used for heat or further transported into a steam turbine for additional power production. A
portion of the cooled combustion product gases from the heat recovery unit, typically at a temperature of about 100 degrees centigrade, may used to dilute the fresh inlet air. This has the advantage of raising the combustor inlet temperature and improving combustion stability.
Preferably however, combustion product gases are further cooled such as to a temperature below about 50 degrees centigrade, as for example by passage through a water spray tower or a secondary heat exchanger before being mixed with the fresh air supplied to the compressor.
[0011] In order to maximize turbine efficiency, the temperature of the recycled exhaust gas is such that when mixed with the ambient air, the temperature of the admixture supplied to the gas turbine is close to the gas turbine design value. The temperature of the inlet mixture to the compressor can be readily controlled by bypassing a controlled amount of exhausted gas around the secondary chiller. To maximize mass flow through the compressor (and thus maximize power), the temperature the recycled exhaust gas should be as close as feasible to that of the ambient air supplied to the gas w turbine or even lower. Advantageously, combustion is stabilized using a catalytic combustor.
[0012] It is a significant discovery that stable fuel-lean combustion can be achieved in a gas turbine combustor even with a reduction in oxygen content of the combustion air sufficient to significantly reduce the kinetic rate of NOx formation during fuel-lean combustion.
BRIEF DESCRIPTION OF THE DRAWIhTGS
[0013] Figure 1 is a schematic drawing of a typical combined cycle gas turbine system of the present invention.
[0014] Figures 2 and 3 depict respective plots of the calculated NOx emissions for a typical premised combustion of fuel and air with and without the use of EGR of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Figure 1 depicts a schematic of a typical combined cycle gas turbine system 10 of the present invention. As shown in Figure 1, combined cycle gas turbine system 10 comprises compressor 11 supplying compressed air to combustor 14 through flow path 22. Fuel 13 enters combustor 14 through flow path 23 wherein it is preferably premixed with the compressed air prior to combustion. Hot combustion products are transported to turbine 12 through flow path 32. Turbine 12 and steam turbine 18 turn and power generator 16. Exhaust gases from turbine 12 are supplied to heat recovery boiler 20 through flow path 33. The steam produced is supplied to steam turbine 18 through flow path 40. The cooled exhaust gases 37 exit through flow path 34 with a portion being supplied to supplemental cooler 50 through flow path 35 for recycle to the compressor 11 inlet through flow path 36. Cooler 50 comprises a heat exchanger further comprising a coolant 38. Fresh air 40 for combustion is added to the recycled exhaust gases in flow path 36, through flow path 21, and both flows mix prior to entry into compressor 11.
Advantageously, combustor 14 is a catalytic combustor, as for example as described in US Patent No. 6,358,040.
[4016] Figure 2 depicts the calculated NOx emissions for a typical premixed combustion of fuel and air, with and without the use of providing EGR to the inlet fresh combustion air. As shown in figure 2, NOx formation at a combustion temperature of 2'750° F is lowered from more than 5 ppm to 3 ppm by use of EGR to lower the oxygen content of the inlet air to 15 percent. Plug flow residence time is thirty milliseconds.
Oxygen content can be lowered further resulting in lower NOx emissions. Inlet air oxygen contents as low as about 11 percent are feasible. Figure 3 depicts the calculated NOx comparison for a similar combustor having a plug flow residence time of only fifteen milliseconds. As shown in Figure 3, the NOx reduction of EGR applies even for reduced residence time combustors.
[0009] In the present invention, fresh inlet air is mixed with cooled combustion gases in sufficient quantity to reduce the oxygen content of the resulting mixture, preferably to at least eighteen mole percent, more preferably about fifteen mole percent or lower. Sufficient oxygen must be present to achieve a mixture with fuel, at the combustor inlet temperature, having the required flame temperature.
Advantageously, the combustion products may contain less than one percent residual oxygen. In order to achieve complete combustion of fuel, it is preferred that the combustion comprises a fuel-lean ratio having an equivalence ratio greater than about 0.55 and more preferably greater than about 0.6.
[0010] In a preferred method of the present invention, the inlet air is minced with cooled combustion product gas prior to entering the compressor of a gas turbine.
Optionally, the cooled combustion gases may be compressed separately and then mixed with compressed air exiting the gas turbine compressor. After compression, the compressed air mixture is mixed with fuel and combusted thereby producing hot combustion products that are expanded in the turbine to produce power and hot exhaust gas. The exhaust gas is then transported into a heat recovery unit. Typically, the heat recovery unit comprises a steam boiler in which case the steam may be used for heat or further transported into a steam turbine for additional power production. A
portion of the cooled combustion product gases from the heat recovery unit, typically at a temperature of about 100 degrees centigrade, may used to dilute the fresh inlet air. This has the advantage of raising the combustor inlet temperature and improving combustion stability.
Preferably however, combustion product gases are further cooled such as to a temperature below about 50 degrees centigrade, as for example by passage through a water spray tower or a secondary heat exchanger before being mixed with the fresh air supplied to the compressor.
[0011] In order to maximize turbine efficiency, the temperature of the recycled exhaust gas is such that when mixed with the ambient air, the temperature of the admixture supplied to the gas turbine is close to the gas turbine design value. The temperature of the inlet mixture to the compressor can be readily controlled by bypassing a controlled amount of exhausted gas around the secondary chiller. To maximize mass flow through the compressor (and thus maximize power), the temperature the recycled exhaust gas should be as close as feasible to that of the ambient air supplied to the gas w turbine or even lower. Advantageously, combustion is stabilized using a catalytic combustor.
[0012] It is a significant discovery that stable fuel-lean combustion can be achieved in a gas turbine combustor even with a reduction in oxygen content of the combustion air sufficient to significantly reduce the kinetic rate of NOx formation during fuel-lean combustion.
BRIEF DESCRIPTION OF THE DRAWIhTGS
[0013] Figure 1 is a schematic drawing of a typical combined cycle gas turbine system of the present invention.
[0014] Figures 2 and 3 depict respective plots of the calculated NOx emissions for a typical premised combustion of fuel and air with and without the use of EGR of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Figure 1 depicts a schematic of a typical combined cycle gas turbine system 10 of the present invention. As shown in Figure 1, combined cycle gas turbine system 10 comprises compressor 11 supplying compressed air to combustor 14 through flow path 22. Fuel 13 enters combustor 14 through flow path 23 wherein it is preferably premixed with the compressed air prior to combustion. Hot combustion products are transported to turbine 12 through flow path 32. Turbine 12 and steam turbine 18 turn and power generator 16. Exhaust gases from turbine 12 are supplied to heat recovery boiler 20 through flow path 33. The steam produced is supplied to steam turbine 18 through flow path 40. The cooled exhaust gases 37 exit through flow path 34 with a portion being supplied to supplemental cooler 50 through flow path 35 for recycle to the compressor 11 inlet through flow path 36. Cooler 50 comprises a heat exchanger further comprising a coolant 38. Fresh air 40 for combustion is added to the recycled exhaust gases in flow path 36, through flow path 21, and both flows mix prior to entry into compressor 11.
Advantageously, combustor 14 is a catalytic combustor, as for example as described in US Patent No. 6,358,040.
[4016] Figure 2 depicts the calculated NOx emissions for a typical premixed combustion of fuel and air, with and without the use of providing EGR to the inlet fresh combustion air. As shown in figure 2, NOx formation at a combustion temperature of 2'750° F is lowered from more than 5 ppm to 3 ppm by use of EGR to lower the oxygen content of the inlet air to 15 percent. Plug flow residence time is thirty milliseconds.
Oxygen content can be lowered further resulting in lower NOx emissions. Inlet air oxygen contents as low as about 11 percent are feasible. Figure 3 depicts the calculated NOx comparison for a similar combustor having a plug flow residence time of only fifteen milliseconds. As shown in Figure 3, the NOx reduction of EGR applies even for reduced residence time combustors.
Claims (10)
1. A method of lowered NOx combustion wherein the kinetic rate of NOx formation is reduced at a given combustion temperature, comprising:
a. providing a supply of fuel to a gas turbine combustor;
b. obtaining a supply of ambient air in sufficient quantity to form a fuel/air mixture having an equivalence ratio greater than about 0.55 when mixed with the fuel;
c. obtaining a supply of cooled combustion gases in sufficient quantity such that if mixed with the air that the oxygen content of the resulting air mixture is less than about 18 percent;
d. mixing the air with the cooled combustion gases and;
e. supplying the air mixture to the combustor.
a. providing a supply of fuel to a gas turbine combustor;
b. obtaining a supply of ambient air in sufficient quantity to form a fuel/air mixture having an equivalence ratio greater than about 0.55 when mixed with the fuel;
c. obtaining a supply of cooled combustion gases in sufficient quantity such that if mixed with the air that the oxygen content of the resulting air mixture is less than about 18 percent;
d. mixing the air with the cooled combustion gases and;
e. supplying the air mixture to the combustor.
2. The method of claim 1wherein the fuel/air mixture has a fuel-lean equivalence ratio greater than about 0.6.
3. The method of claim 1 wherein the air mixture is compressed in a gas turbine compressor prior to entering the combustor.
4. The method of claim 1 wherein the air and the cooled combustion gases are compressed prior to mixing.
5. The method of claim 1 wherein the cooled combustion gases have a temperature less than about 150 degrees Celsius.
6. The method of claim 1 wherein the gas turbine combustor is installed in a combined cycle gas turbine.
7. The method of claim 1 wherein the fuel is premixed with the air mixture prior to combustion.
8. The method of claim 1 wherein the combustor is a catalytic combustor.
9. The method of claim 3 wherein the temperature of the mixture supplied to the compressor is maintained at a predetermined value.
10. The method of claim 1 wherein the amount of ambient air supplied is controlled to maintain the oxygen concentration in the combustion gases below about one percent.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47668803P | 2003-06-06 | 2003-06-06 | |
| US60/476,688 | 2003-06-06 | ||
| PCT/US2004/017920 WO2004109075A1 (en) | 2003-06-06 | 2004-06-04 | METHOD FOR OBTAINING ULTRA-LOW Nox EMISSIONS FROM GAS TURBINES OPERATING AT HIGH TURBINE INLET TEMPERATURES |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2527948A1 true CA2527948A1 (en) | 2004-12-16 |
Family
ID=33511808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002527948A Abandoned CA2527948A1 (en) | 2003-06-06 | 2004-06-04 | Method for obtaining ultra-low nox emissions from gas turbines operating at high turbine inlet temperatures |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2527948A1 (en) |
| DE (1) | DE112004000994T5 (en) |
| WO (1) | WO2004109075A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2584749C1 (en) * | 2014-12-22 | 2016-05-20 | Федеральное государственное унитарное предприятие "Государственный космический научно-производственный центр имени М.В. Хруничева" | Turbo compressor power plant |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7350471B2 (en) * | 2005-03-01 | 2008-04-01 | Kalex Llc | Combustion system with recirculation of flue gas |
| US20080141645A1 (en) | 2006-12-14 | 2008-06-19 | General Electric Company | System and method for low emissions combustion |
| US8087248B2 (en) | 2008-10-06 | 2012-01-03 | Kalex, Llc | Method and apparatus for the utilization of waste heat from gaseous heat sources carrying substantial quantities of dust |
| US8695344B2 (en) | 2008-10-27 | 2014-04-15 | Kalex, Llc | Systems, methods and apparatuses for converting thermal energy into mechanical and electrical power |
| US8176738B2 (en) | 2008-11-20 | 2012-05-15 | Kalex Llc | Method and system for converting waste heat from cement plant into a usable form of energy |
| EP2348256A1 (en) * | 2010-01-26 | 2011-07-27 | Alstom Technology Ltd | Method for operating a gas turbine and gas turbine |
| US8474263B2 (en) | 2010-04-21 | 2013-07-02 | Kalex, Llc | Heat conversion system simultaneously utilizing two separate heat source stream and method for making and using same |
| CH703218A1 (en) | 2010-05-26 | 2011-11-30 | Alstom Technology Ltd | Method of operating a combined cycle with flue gas recirculation and power plant. |
| CH704118A1 (en) * | 2010-11-17 | 2012-05-31 | Alstom Technology Ltd | Method for operating combined cycle power plant, involves controlling combustion in-homogeneity ratio as function of flue gas recirculation rate of gases, and re-circulating flue gases into compressor inlet air of gas turbine |
| DE102011102720B4 (en) | 2010-05-26 | 2021-10-28 | Ansaldo Energia Switzerland AG | Combined cycle power plant with exhaust gas recirculation |
| DE102011115364A1 (en) | 2010-10-19 | 2012-04-19 | Alstom Technology Ltd. | power plant |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2624172A (en) * | 1947-11-01 | 1953-01-06 | Eugene J Houdry | Process of generating power involving catalytic oxidation |
| US4040252A (en) * | 1976-01-30 | 1977-08-09 | United Technologies Corporation | Catalytic premixing combustor |
| US4271664A (en) * | 1977-07-21 | 1981-06-09 | Hydragon Corporation | Turbine engine with exhaust gas recirculation |
| US4498298A (en) * | 1983-09-15 | 1985-02-12 | Morgan George R | Stirling cycle piston engine |
-
2004
- 2004-06-04 CA CA002527948A patent/CA2527948A1/en not_active Abandoned
- 2004-06-04 DE DE112004000994T patent/DE112004000994T5/en not_active Ceased
- 2004-06-04 WO PCT/US2004/017920 patent/WO2004109075A1/en active Application Filing
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2584749C1 (en) * | 2014-12-22 | 2016-05-20 | Федеральное государственное унитарное предприятие "Государственный космический научно-производственный центр имени М.В. Хруничева" | Turbo compressor power plant |
Also Published As
| Publication number | Publication date |
|---|---|
| DE112004000994T5 (en) | 2006-06-14 |
| WO2004109075A1 (en) | 2004-12-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |
Effective date: 20130826 |