APPARATUS/METHOD FOR COOLING COMBUSTION CHAMBER/VENTURI IN LOW NOX COMBUSTOR

PROBLEM TO BE SOLVED: To provide an apparatus capable of reducing emissions of nitrogen oxides in a gas turbine combustion system. SOLUTION: A dry NOx emission combustor 30 includes a premixing chamber 36 for mixing fuel with cooling gas and a combustion chamber 32 positioned downstream of the premixing chamber 36 for the combustion of pre-mixed fuel and cooling gas. The combustor 30 further includes a venturi 46 which is positioned between the premixing chamber 36 and the combustion chamber 32 and has annular walls including converging and diverging wall portions 41, 43 defining a constricted portion and through which the premixed fuel and air pass to the combustion chamber 32. The walls define a passage 44 where cooling gas flows along the combustion chamber 32 and have an exit 64 for flowing cooling gas to inside of the combustion chamber 32. A plurality of inlets 56 at the converging and diverging wall portions 41, 43 ingest cooling gas into the passage 44 to produce an impingement cooling effect. A plurality of turbulators 62 disposed downstream of the inlets 56 interact with the cooling gas to produce a turbulent cooling effect. The combustor 30 is effectively fired over a temperature range to reduce the NOx emissions of the combustor 30. COPYRIGHT: (C)2009,JPO&INPIT