Carbon dioxide power cycle

An improved direct fired power system generating and employing a combustion gas which includes carbon dioxide as a working fluid comprising:

• means defining a combustion chamber for burning a mixture which includes oxygen, a carbonaceous fuel and recycled carbon dioxide working fluid at a supercritical first pressure, thereby providing a combustion gas which includes carbon dioxide and water at substantially said first pressure, and a supercritical temperature,
• means defining a first turbine for receiving combustion gas from said combustion chamber and allowing said gas to expand therethrough to generate power and reduce the pressure of said combustion gas to a second pressure while maintaining a supercritical state,
• means for receiving said combustion gas from said first turbine and heating said gas at said second pressure to a higher temperature
• means defining a second turbine for receiving combustion gas from said means for heating and allowing said gas to expand therethrough to generate power and further reduce the pressure on said combustion gas to a third pressure while maintaining a supercritical state,
• means defining a heat exchanger having first and second ducts in heat exchange relationship, said first duct receiving combustion gas from said second turbine and conducting said gas therethrough, said second duct conducting recycled carbon dioxide working fluid at substantilly said first pressure and a temperature below that of said combustion gas in said first duct therethrough and having an output connected to said combustion chamber for providing at least a portion of said recycled carbon dioxide thereto, for enabling said combustion gas to transfer heat to said recycled carbon dioxide to condense at least a portion of the water in said combustion gas, but maintain the carbon dioxide thereof in a supercritical state,
• means for separating the condensed water from the remainder of said combustion gas
• first cooling means connected to the output of said first duct of said heat exchanger for receiving combustion gas therefrom and cooling said combustion gas to a supercritical first temperature,
• first compression means for receiving said combustion gas from said first cooling means and compressing said combustion gas to a fourth pressure below said first pressure,
• second cooling means for receiving said combustion gas from said first compression means and cooling said combustion gas to a second temperature at essentially the liquid/gas interface of said combuston gas and,
• second compression means for receiving said combustion gas from said second cooling means and compressing said gas to substantially said first pressure to thereby provide said recycled carbon dioxide working fluid, said second compression means being connected to the input of said second duct of said heat exchanger for providing said recycled carbon dioxide thereto.