Hybrid expander cycle with turbo-generator and cooled power electronics
A gas turbine engine system includes a gas turbine engine and a turbo-generator. The gas turbine engine includes a heat exchange system configured to transfer thermal energy from an air flow (i.e., inlet air flow or exhaust gas flow) to a fuel to produce a gaseous fuel. The turbo-generator includes a fuel turbine fluidly coupled to the heat exchange system and a combustor of the gas turbine engine, a fuel pump configured to be driven by the fuel turbine and fluidly coupled to the heat exchange system, and a motor/generator configured to be driven by the fuel turbine. The fuel turbine is configured to extract energy from expansion of the gaseous fuel to produce a gaseous fuel for combustion in the combustor. The motor/generator includes a cooling jacket, which is fluidly coupled to the fuel pump.
1. A method of operating a gas turbine engine system, the method comprising:
receiving an inlet air flow from an inlet of a gas turbine engine of the gas turbine engine system;
cooling the inlet air flow of the gas turbine engine via a first heat exchanger of a heat exchange system of the gas turbine engine to produce a cooled air flow, wherein the cooling comprises transferring thermal energy from the inlet air flow to a cryogenic liquid fuel;
compressing the cooled air flow in a compressor of the gas turbine engine to produce a compressed air flow;
vaporizing the cryogenic liquid fuel to produce a gaseous fuel, wherein the cryogenic fuel is vaporized in one of the first heat exchanger or a second heat exchanger of the heat exchange system;
extracting energy from expansion of the gaseous fuel through a fuel turbine of a turbo-generator, wherein expansion of the gaseous fuel produces a gaseous fuel having a pressure greater than a pressure of the compressed air flow, wherein the fuel turbine is fluidly coupled to the heat exchange system and a combustor of the gas turbine engine;
wherein the turbo-generator further comprises:
a fuel pump configured to be driven by the fuel turbine and to deliver the cryogenic liquid fuel to the first heat exchanger, the fuel pump being fluidly coupled to a fuel tank configured to store the cryogenic fuel and fluidly coupled to the first heat exchanger; and
a motor/generator configured to be driven by the fuel turbine;
combusting a mixture of the gaseous fuel received from an outlet of the fuel turbine and the compressed air flow received from the compressor in the combustor of the gas turbine engine to produce a combustion gas flow, wherein the gaseous fuel from the fuel turbine is received at the combustor at a first pressure and wherein the gaseous fuel produced by the heat exchange system is at a second pressure greater than the first pressure;
extracting energy from expansion of the combustion gas flow in a turbine of the gas turbine engine, the turbine fluidly coupled to the combustor and configured to produce an exhaust gas flow, wherein the second heat exchanger is configured to transfer thermal energy from the exhaust gas flow to produce the gaseous fuel;
cooling the motor/generator, wherein the motor/generator comprises a cooling jacket fluidly coupled to the fuel tank and the fuel pump and positioned in fluid communication between the fuel tank and the fuel pump.
2. The method of claim 1 , wherein the cryogenic liquid fuel is selected from the fuels consisting of liquid hydrogen and liquefied natural gas.
3. The method of claim 2 , wherein the cryogenic liquid fuel is at a temperature below −350° F. (−212° C.).
4. The method of claim 1 , and further comprising delivering the gaseous fuel from the first heat exchanger directly to the fuel turbine.
5. A gas turbine engine system comprising:
a fuel tank for storing a cryogenic fuel;
a gas turbine engine comprising:
an air inlet configured to receive an inlet air flow; and
a turbo-generator system comprising:
a fuel turbine configured to extract energy from expansion of a gaseous fuel;
a fuel pump configured to be driven by the fuel turbine and to deliver the cryogenic liquid fuel to the gas turbine engine for combustion;
a motor/generator configured to be driven by the fuel turbine, the motor/generator comprising a cooling jacket fluidly coupled to the fuel pump and configured to cool the motor/generator with the cryogenic liquid fuel, wherein the cooling jacket is positioned in fluid communication between the fuel tank and the fuel pump; and
a heat exchange system in fluid communication with the fuel pump and configured to transfer thermal energy to the cryogenic liquid fuel to produce the gaseous fuel supplied to the fuel turbine, the heat exchange system comprising an inlet heat exchanger configured to transfer thermal enemy from the inlet air flow to the cryogenic liquid fuel.
6. The gas turbine engine system of claim 5 , wherein the fuel turbine is fluidly connected to a combustor of the gas turbine engine and configured to deliver the gaseous fuel to the combustor.
7. The gas turbine engine system of claim 6 , wherein the heat exchange system further comprises an exhaust heat exchanger, and wherein each of the inlet heat exchanger and the exhaust heat exchanger is configured to deliver the gaseous fuel directly to the fuel turbine.
8. A gas turbine engine system comprising:
a gas turbine engine comprising:
an air inlet configured to receive an inlet air flow;
a compressor configured to compress the inlet air flow to produce a compressed air flow;
a combustor fluidly coupled to the compressor and configured to combust a mixture of the compressed air flow and a gaseous fuel to produce a combustion gas flow, the gaseous fuel being at a first pressure;
a turbine fluidly coupled to the combustor and configured to extract energy from expansion of the combustion gas flow to produce an exhaust gas flow; and
a heat exchange system, the heat exchange system comprising an inlet heat exchanger configured to transfer thermal energy from the inlet air flow to a fuel, the heat exchange system configured to produce the gaseous fuel at a second pressure greater than the first pressure; and
a turbo-generator comprising:
a fuel turbine fluidly coupled to the heat exchange system and the combustor, wherein the fuel turbine is configured to extract energy from expansion of the gaseous fuel at the second pressure, and wherein the gas turbine engine system is configured to provide the expanded gaseous fuel from the fuel turbine to the combustor at the first pressure;
a fuel pump configured to be driven by the fuel turbine and to deliver a cryogenic fuel, wherein the fuel pump is fluidly coupled to a fuel tank configured to store the cryogenic fuel and fluidly coupled to the heat exchange system; and
a motor/generator comprising a cooling jacket, wherein the motor/generator is configured to be driven by the fuel turbine and wherein the cooling jacket is fluidly coupled to the fuel tank and the fuel pump and positioned in fluid communication between the fuel tank and the fuel pump.
9. The gas turbine engine system of claim 1 , wherein the inlet heat exchanger is in direct fluid communication with the fuel pump.
10. The gas turbine engine system of claim 1 , wherein the heat exchange system further comprises an exhaust heat exchanger fluidly coupled to the inlet heat exchanger and configured to transfer thermal energy from the exhaust gas flow to the fuel received from the inlet heat exchanger.
11. The gas turbine engine system of claim 10 , wherein the fuel turbine is in direct fluid communication with the exhaust heat exchanger.
12. The gas turbine engine system of claim 10 , wherein the fuel turbine comprises multiple stages.
13. The gas turbine engine system of claim 10 , wherein the fuel pump and the motor/generator are mechanically coupled to a rotor shaft of the fuel turbine.
14. The gas turbine engine system of claim 8 , wherein the cryogenic fuel is at a temperature below −350° F. (−212° C.).
15. The gas turbine engine system of claim 8 , wherein the heat exchange system further comprises and an exhaust heat exchanger, and wherein each of the inlet heat exchanger and the exhaust heat exchanger is configured to deliver the gaseous fuel directly to the fuel turbine.