Semi-closed Brayton cycle gas turbine power systems

A method for starting a semi-closed Brayton cycle power system including the steps of:

• providing a semi-closed Brayton cycle power generation system including:
• a gas compressor having an inlet and an outlet;
• a combustor downstream of the compressor, the combustor having a fuel port coupled to a source of fuel, an oxidizer port coupled to the compressor outlet and an outlet port for combustion products resulting from combustion of fuel from the source of fuel with oxidizer from the oxidizer port;
• a turbine downstream of the combustor, the turbine having an input coupled to the combustor outlet port, an output for the combustion products entering the turbine at the input, and a power output;
• a return duct downstream of the turbine, the return duct receiving at least a portion of the combustion products passing through the output of the turbine and extending to the inlet of the compressor;
• a gaseous oxygen duct coupled to a source of oxygen and coupled to the return duct in a manner adding oxygen to the combustion products within the return duct;
• the gaseous oxygen duct located upstream of the gas compressor, such that at least a portion of the oxygen from the gaseous oxygen duct enters the compressor inlet along with the combustion products;
• and
• wherein an air inlet duct is coupled to the return duct at a location upstream of the gas compressor;
• opening the air inlet duct so that air can pass into the return duct upstream of the compressor inlet;
• keeping the oxygen duct initially closed;
• starting the combustor, the turbine and the compressor of the semi-closed Brayton cycle power generation system;
• opening the oxygen duct;
• and
• closing the air inlet duct.

A semi-closed Brayton cycle power generation system, comprising in combination:

• a gas compressor having an inlet and an outlet;
• a combustor downstream of said compressor, said combustor having a fuel port coupled to a source of fuel, an oxidizer port coupled to said compressor outlet and an outlet port for combustion products resulting from combustion of fuel from said source of fuel with oxidizer from said oxidizer port;
• a turbine downstream of said combustor, said turbine having an input coupled to said combustor outlet port, an output for the combustion products entering said turbine at said input, and a power output;
• a return duct downstream of said turbine, said return duct receiving at least a portion of the combustion products passing through said output of said turbine and extending to said inlet of said compressor;
• a gaseous oxygen duct coupled to a source of oxygen and coupled to said return duct in a manner adding oxygen to the combustion products within said return duct;
• said gaseous oxygen duct located upstream of said gas compressor, such that at least a portion of the oxygen from said gaseous oxygen duct enters said compressor inlet along with the combustion products;
• said source of oxygen including an ion transfer membrane between an air inlet and an oxygen outlet, said oxygen outlet coupled to said gaseous oxygen duct;
• and
• an air heater between said air inlet and said membrane, said heater transferring heat from the combustion products downstream of said combustor into the air entering said air inlet.