ep 0 718 470 a2 and b1 relating to method of operating a gas turbine group equipped with two combustor chambers when providing a partial load operation other relevant published documents which include one or more improvements of the above identified documents forming also integral parts of the present description referring to a sequential combustion the combination of combustors can be disposed as follows at least one combustor is configured as a can architecture with at least one operating turbine both the first and second combustors are configured as sequential can can architecture with at least one operating turbine the first combustor is configured as an annular combustion chamber and the second combustor is built on as a can configuration with at least one operating turbine the first combustor is configured as a can architecture and the second combustor is configured as an annular combustion chamber with at least one operating turbine both the first and second combustor are configured as annular combustion chambers with at least one operating turbine both the first and second combustor are configured as annular combustion chambers with an intermediate operating turbine in both cases relating to can combustor 120 or annular combustion chamber 130 the azimuthal main flow 121 131 is unitary in each system fig2 shows a gas turbine according to fig1 having a first combustion chamber equipped with at least one dilution air injection 201 at appropriate place downstream of the first burner system 101 and upstream of the second burner system 105 and having a second.