# US 10,502,423 B2 · Sequential combustion with dilution gas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,423 B2 - Document ID: US10502423B2 - Status: Granted - Kind: B2 - Application number: 14/918,787 - Filed: 2015-10-21 - Published: 2016-02-11 - Granted: 2019-12-10 - Earliest claimed: 2014-03-06 - Assignees: Ansaldo Energia Switzerland AG - Applicants: Alstom Technology Ltd - Inventors: Xianfeng Gao; Luis Tay Wo Chong Hilares - Web page: https://patentgrep.com/patent/US10502423B2 ## CPC - F23R 3/06: Arrangement of apertures along the flame tube - F02C 6/02: Plural gas-turbine plants having a common power output - F23M 20/005: {Noise absorbing means} - F23R 3/002: {Wall structures (F23R3/02 and F23R3/007 take precedence)} - F23R 3/346: {for staged combustion} - F05D 2220/32: in gas turbines - F05D 2240/35: Combustors or associated equipment - F05D 2260/964: counteracting thermoacoustic noise - F23R 2900/00014: Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators - F23R 2900/03341: Sequential combustion chambers or burners - Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] - F23R: GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS (fluidised bed combustion apparatus specially adapted for operation at superatmospheric pressures F23C10/16) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F23M: CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract An exemplary sequential combustor arrangement includes a first burner, a first combustion chamber, a mixer for admixing a dilution gas to the hot gases leaving the first combustion chamber during operation, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection. The mixer includes at least three groups of injection tubes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot flue gases leaving the first combustion chamber. The first injection tubes of the first group have a first protrusion depth, the second injection tubes of the second group have a protrusion depth, and the third injection tubes of the third group have a third protrusion depth. ## Claims ### Claim 1 A sequential combustor arrangement comprising: a first burner, a first combustion chamber, a mixer for admixing a dilution gas to hot gases leaving the first combustion chamber during operation, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection, wherein the mixer is configured to guide combustion gases in a hot gas flow path extending between the first combustion chamber and the second burner with a duct having an inlet at an upstream end configured for connection to the first combustion chamber and an outlet at a downstream end configured for connection to the second burner; wherein the mixer includes a first group of first injection tubes pointing inwards from side walls of the mixer for admixing the dilution gas to cool the hot gases when leaving the first combustion chamber, a second group of second injection tubes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot gases when leaving the first combustion chamber, and a third group of third injection tubes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot gases when leaving the first combustion chamber, wherein: the first injection tubes of the first group are circumferentially distributed along the side walls of the mixer, the second injection tubes of the second group are circumferentially distributed along the side walls of the mixer, the third injection tubes of the third group are circumferentially distributed along the side walls of the mixer; and wherein the first injection tubes of the first group have a first protrusion depth into the hot gas flow path, the second injection tubes of the second group have a second protrusion depth into the hot gas flow path, and the third injection tubes of the third group have a third protrusion depth into the hot gas flow path; the second protrusion depth being bigger than the third protrusion depth and the second protrusion depth being smaller than the first protrusion depth; the side walls of the mixer having diffusion cooling holes, at least some of the diffusion cooling holes positioned in a first region that has a trapezoidal shape, the first region extending in a main flow direction of the hot gases from adjacent at least one of the first injection tubes to a position adjacent at least one of the third injection tubes, the first region being positioned downstream of a second region that is homogenously cooled, the first region also being upstream of the third injection tubes, the first region also being located between immediately adjacent second injection tubes of the second injection tubes of the second group and downstream of the first injection tubes, the first region comprising a different hole spacing from a third region that is circumferentially adjacent to the trapezoidal shape. ### Claim 2 (depends on 1) The sequential combustor arrangement according to claim 1, wherein a distance in a the main flow direction between a center point of one of the first injection tubes and a center point of one of the second injection tubes is between 0.1 and 2 times a diameter of the one of the first injection tubes. ### Claim 3 (depends on 1) The sequential combustor arrangement according to claim 1, wherein a distance in the main flow direction between a center point of one of the second injection tubes and a center point of one of the third injection tubes is between 0.1 and 2 times a diameter of one of the second injection tubes. ### Claim 4 (depends on 1) The sequential combustor arrangement according to claim 1, wherein the mixer has a fourth region defined adjacent an exit of the mixer, the fourth region defined such that no diffusion holes are positioned in the fourth region. ### Claim 5 (depends on 1) The sequential combustor arrangement according to claim 1, wherein the trapezoidal shape of the first region has an upstream base adjacent the at least one of the third injection tubes, the upstream base extending in a direction that is normal to the a main flow direction for the hot gases and the trapezoidal shape of the first region has a downstream base that is longer than the an upstream base, the downstream base extending in the direction that is normal to the main flow direction for the hot gases. ### Claim 6 (depends on 5) The sequential combustor arrangement according to claim 5, wherein the upstream base has a length that is 1 to 2 times a diameter of one of the first injection tubes; and wherein a density of the diffusion holes in the first region is greater than a density of the diffusion holes in the second region. ### Claim 7 (depends on 5) The sequential combustor arrangement according to claim 5, wherein legs of the trapezoidal shape of the first region extend between the upstream base and the downstream base at an angle of between 30° and 45° relative to the main flow direction. ### Claim 8 (depends on 1) The sequential combustor arrangement according to claim 1, wherein a diameter of one of the first injection tubes is larger than a diameter of one of the second injection tubes, and/or the diameter of one of the second injection tubes is larger than a diameter of one of the third injection tubes. ### Claim 9 (depends on 1) The sequential combustor arrangement according to claim 1, wherein the first injection tubes are circumferentially distributed in a plane normal to the main flow direction for the hot gases when flowing through the mixer, and the second injection tubes are circumferentially distributed in a plane normal to the main flow direction of the hot gases flowing through the mixer. ### Claim 10 (depends on 1) The sequential combustor arrangement according to claim 1, wherein the third injection tubes are staggered relative to a plane normal to the main flow direction of the hot gases flowing through the mixer, wherein the stagger is between 0.1 and 3.5 times the diameter of one of the third injection tubes. ### Claim 11 (depends on 1) The sequential combustor arrangement according to claim 1, wherein at least part of an outer surface of the first injection tubes and/or at least part of an inner surface of the side walls of the mixer is coated with a thermal barrier coating. ### Claim 12 (depends on 1) The sequential combustor arrangement according to claim 1, wherein cooling ribs and/or a pin field is arranged on an inner surface of the first injection tubes. ### Claim 13 (depends on 1) A gas turbine comprising: at least one compressor, a combustor, and at least one turbine, the combustor being a sequential combustor arrangement according to claim 1. ### Claim 14 A method for operating a gas turbine having at least a compressor, and a sequential combustor arrangement including a first burner, a first combustion chamber, a mixer, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection, wherein the mixer is configured to guide combustion gases in a hot gas flow path extending between the first combustion chamber and the second burner with a duct having an inlet at an upstream end configured for connection to the first combustion chamber and an outlet at a downstream end configured for connection to the second burner, wherein the mixer includes a first group of first injection tubes pointing inwards from side walls of the mixer for admixing dilution gas to cool hot flue gases when leaving the first combustion chamber, a second group of second injection tubes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot flue gases when leaving the first combustion chamber, and a third group of third injection tubes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot flue gases when leaving the first combustion chamber, wherein: the first injection tubes of the first group are distributed along the side walls of the mixer, the second injection tubes of the second group are distributed along the side walls of the mixer, the third injection tubes of the third group are distributed along the side walls of the mixer; and wherein the first injection tubes of the first group have a first protrusion depth into the hot gas flow path, the second injection tubes of the second group have a second protrusion depth into the hot gas flow path, and the third injection tubes of the third group have a third protrusion depth into the hot gas flow path; the second protrusion depth being bigger than the third protrusion depth and the second protrusion depth being smaller than the first protrusion depth, and the side walls of the mixer having diffusion cooling holes, at least some of the diffusion cooling holes positioned in a first region that has a trapezoidal shape, the first region extending in a main flow direction of the hot gases from adjacent at least one of the first injection tubes to a position adjacent at least one of the third injection tubes, the first region being positioned downstream of a second region that is homogenously cooled, the first region also being upstream of the third injection tubes, the first region also being located in a space between immediately adjacent second injection tubes of the second injection tubes of the second group and downstream of the first injection tubes, the first region comprising a different hole spacing from a third region that is circumferentially adjacent to the trapezoidal shape; wherein the method comprising: guiding, in the mixer, combustion gases in the hot gas flow path extending between the first combustion chamber and the second burner; and admixing, in the mixer, the dilution gas to the hot gases leaving the first combustion chamber, wherein the dilution gases are admixed via the first injection tubes, the second injection tubes, and the third injection tubes of the mixer to cool the hot flue gases leaving the first combustion chamber, and the dilution gases are admixed in different regions of a cross section of the mixer via the first injection tubes, the second injection tubes, and the third injection tubes. ### Claim 15 (depends on 14) The method of claim 14, wherein the first injection tubes are arranged upstream of the second injection tubes. ### Claim 16 (depends on 15) The method of claim 15, wherein the first injection tubes are arranged upstream of the third injection tubes; and the admixing of the diffusion gas occurs such that there is a pressure drop of 0.4% to 2% of a total pressure of the dilution gas pressure before admixing or a pressure drop of 0.2% to 1% of the total pressure of the dilution gas pressure before admixing. ### Claim 17 (depends on 14) The method of claim 14, wherein cooling ribs and/or a pin field is arranged on an inner surface of the first injection tubes. ### Claim 18 (depends on 14) The method of claim 14, wherein the first injection tubes have a first diameter, the second injection tubes have a second diameter, and the third injection tubes have a third diameter, the second diameter being smaller than the first diameter and the second diameter being larger than the third diameter. ### Claim 19 (depends on 14) The method of claim 14, wherein the third injection tubes are arranged such that the third injection tubes are staggered relative to a plane normal to the main flow direction of the hot gases flowing through the mixer; and the trapezoidal shape of the first region has an upstream base adjacent at least one of the third injection tubes, the upstream base extending in a direction that is normal to the main flow direction for the hot gases and the trapezoidal shape of the first region has a downstream base that is longer than the upstream base, the downstream base extending in the direction that is normal to the main flow direction for the hot gases adjacent some of the first injection tubes, the upstream base having a length that is 1 to 2 times a diameter of one of the first injection tubes, legs of the trapezoidal shape of the first region extending between the upstream base and the downstream base at an angle of between 30° and 45° relative to the main flow direction.