Abstract: The present invention relates to a combined cycle power plant comprising a air compressor providing pressurized air at pressure greater than 2 bar; a gas turbine means for driving the gas compressor means; a pressure vessel, circular in cross-section, connected to said air compressor and being capable of withstanding pressures greater than 2 bar; a pressurized circulating fluidized bed reactor enclosed by the pressure vessel, the circulating fluidized bed reactor having a reactor chamber, including substantially planar steam generation tube walls having a bottom section; means for leading hot combustion gases away from said reactor; one or more non-circular centrifugal separator(s) disposed within said pressure vessel being adapted to the reactor chamber and internal pressure vessel geometry for receiving and purifying hot combustion gases, having a gas outlet leading from said separator out of said pressure vessel; said centrifugal separator comprising a vertical vortex chamber having distinctly planar steam

Abstract: A pressurized fluidized bed reactor is provided utilizing a centrifugal separator having a gas space that is distinctly non-circular, preferably having a circularity of greater than or equal to 1.15. Most desirably the cyclone has a quadrate (e.g. square) cross-section, and is disposed inside of the pressure vessel along with the reactor chamber containing the fluidized bed. A number of ceramic candle or honeycomb filters may be provided connected to the gas outlet from the cyclone separator, within the pressure vessel, to filter the gas. This construction provides a minimized diameter of the pressure vessel because the reactor chamber with square cyclones is more compact than if conventional circular cross-section cyclones are employed. Also a second pressure vessel is not needed for the candle or honeycomb filters since there is sufficient room within the pressure vessel to accommodate them.