Abstract: This disclosure sets forth a combustion device for a power plant wherein a burner includes a central tubular section with an annular section located therearound. Air inlet means directs air to the burner. The central section comprises a premixing chamber and a combustion chamber for burning a fuel-air mixture while the annular section includes a catalytic reaction device. First tubular means directs air inwardly to said central tubular section for mixing with fuel where the fuel-air mixture is then burned. Additional air is added through second tubular means to the exhaust therefrom where it is then directed to one end of the annular section containing the catalytic reaction device. A transition member connects the exhaust end of the annular section to an outlet. Cooling louvers can be provided along this section if necessary. Further, a swirling device is located between the premixing chamber and combustion chamber for greater mixing of fuel and air.