# US 5,349,813 A · Vibration of systems comprised of hot and cold components > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,813 A - Document ID: US5349813A - Status: Granted - Kind: A - Application number: 07/973,022 - Filed: 1992-11-09 - Granted: 1994-09-27 - Earliest claimed: 1992-11-09 - Assignees: Foster Wheeler Energy Corporation - Inventors: Frantisek L. Eisinger - Web page: https://patentgrep.com/patent/US5349813A ## CPC - F01D 25/04: Antivibration arrangements - F01D 25/30: Exhaust heads, chambers, or the like - F01K 23/10: with exhaust fluid of one cycle heating the fluid in another cycle (F01K17/025 takes precedence) - F02G 1/043: the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines - F23M 20/005: {Noise absorbing means} - F02G 2243/54: thermo-acoustic - F23R 2900/00014: Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators - Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D) - F02G: HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS (steam engine plants, special vapour plants, plants operating on either hot gas or combustion-product gases together with other fluid F01K; gas-turbine plants F02C; jet-propulsion plants F02K); USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR - 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 - 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) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A system and method for resisting thermoacoustic oscillations in systems comprised of hot and cold components is disclosed. More particularly, a combined cycle power generation system 32 having a gas turbine 40, a gas turbine discharge duct 34, and a gas turbine recuperator 36 and 38 is disclosed. The system 32 is designed to resist severe thermoacoustic oscillations over its entire load range by providing for an asymmetrical arrangement of the hot section L-l, including the gas discharge duct 34 and the plenum 36 of the recuperator, and the cold section l, including the heat exchange tubes 38 of the recuperator. Also disclosed is a steam generation system 42 having a plenum 46, a burner 48, and a furnace 44. The steam generation system 42 is also designed to resist severe thermoacoustic oscillations by providing for an appropriate burner length L and by providing for an asymmetrical arrangement of a hot burner section L-l and a cold burner section l within the burner 48. Alternative means are also disclosed for avoiding severe thermoacoustic oscillations in the combined cycle generation system and in the steam generation system by disrupting or avoiding the modified Sondhauss effect in those systems. ## Claims ### Claim 1 A system for resisting severe thermoacoustic oscillations, comprising: a component having a relatively cold section and a relatively hot section, said relatively cold section and a relatively hot section, said relatively cold and hot sections being in gas flow communication, and said component having a total effective length L; said relatively cold section having an effective length l and having an average temperature T.sub.c across said length l; said relatively hot section having an effective length L-l and having an average temperature T.sub.h across said length L-l; said temperatures T.sub.c and T.sub.h being subject to variations at different loads for said component and being related by a variable temperature ratio .alpha. which is equal to T.sub.h /T.sub.c ; said component having a known minimum critical temperature ratio .alpha..sub.min below which said component is not subject to thermoacoustic oscillations regardless of selected lengths of said relatively cold section or said relatively hot section; said component having a known maximum operating temperature ratio .alpha..sub.max, said component being subject to severe thermoacoustic oscillations when said maximum temperature ratio .alpha..sub.max is equal to or greater than a critical temperature ratio .alpha..sub.cr ; said relatively cold section length l and said relatively hot section length L-l being selected so that said critical temperature ratio .alpha..sub.cr is greater than said known maximum operating temperature ratio .alpha..sub.max when said critical temperature ratio .alpha..sub.cr is defined as follows: ##EQU11## ### Claim 2 (depends on 1) The system of claim 1 wherein said minimum critical temperature ratio .alpha..sub.min occurs when said relatively cold section length l is equal to said relatively hot section length L-l. ### Claim 3 (depends on 1) The system of claim 1 wherein said component comprises a heat generating source, a heat exchanger, and a duct connecting said heat generating source to said heat exchanger. ### Claim 4 (depends on 3) The system of claim 3 wherein said heat generating source comprises a gas turbine and said heat exchanger comprises a gas turbine recuperator. ### Claim 5 (depends on 4) The system of claim 4 wherein said gas turbine recuperator comprises a plenum and a heat exchange area, said relatively cold section of said component corresponds with said heat exchange area, and said relatively hot section of said component corresponds with said duct and said plenum. ### Claim 6 (depends on 5) The system of claim 5 wherein said relatively hot section length L-l and said relatively cold section length l are selected so that said critical temperature ratio .alpha..sub.cr is sufficient to provide a margin of safety against severe thermoacoustic oscillations. ### Claim 7 (depends on 6) The system of claim 6 wherein said critical temperature ratio .alpha..sub.cr provided is approximately 16% greater than said maximum operating temperature ratio .alpha..sub.max. ### Claim 8 (depends on 6) The system of claim 6 wherein said relatively cold section length l and said relatively hot section length L-l are selected using a value for said minimum critical temperature ratio .alpha..sub.min of approximately 2.14.