Patent ID: 7654089

Claim:
An axially staged annular gas-turbine combustion chamber comprising: a plurality of pilot burners arranged in an annular configuration; at least one pilot zone positioned adjacent the pilot burners; a plurality of main burners arranged in an annular configuration; at least one common main zone positioned adjacent the main burners, the pilot burners and the main burners being axially and radially offset relative to each other with exit portions of the main burners located downstream of exit portions of the pilot burners, said common main zone located downstream of the pilot zone and comprising: an outer flame-tube wall, and an inner flame-tube wall, each wall provided with ports for the introduction of air into the common main zone, with said main burners being radially positioned toward the outer flame-tube wall and with said pilot burners being radially positioned toward the inner flame-tube wall, wherein the outer-flame tube wall ports include a first arrangement of ports including a single first row of ports and the inner flame-tube wall ports include a second arrangement of ports including a single first row of ports, with the ports of the second arrangement being circumferentially aligned off-center with the ports of the first row of the first arrangement, wherein the first arrangement of ports includes a second row of ports, with the ports of the second row being aligned circumferentially off-center with, and positioned rearwards of the ports of the first row of the first arrangement.