Preheating of fluid in a supercritical Brayton cycle power generation system at cold startup

1. A supercritical Brayton cycle power generation system, comprising:

a generator;

a turbine, wherein the turbine comprises an inlet port and an outlet port;

a shaft that operatively couples the turbine to the generator, wherein rotation of the turbine in a first radial direction is operative to cause the generator to output electric power;

a motor;

a compressor, wherein the compressor comprises an inlet port and an outlet port, wherein the motor is operative to drive the compressor;

a first piping that is operative to transport a fluid from the outlet port of the compressor to the inlet port of the turbine;

a second piping that is operative to transport the fluid from the outlet port of the turbine to the inlet port of the compressor;

a fifth piping that is operative to transport the fluid from the first piping to the second piping;

a first valve positioned on the fifth piping that is operative to direct the fluid in the first piping to flow to the second piping when the first valve is open;

a heater coupled to the first piping that is operative to heat the fluid;

a sensor coupled to the first piping that is operative to output a temperature of the fluid at the inlet port of the turbine; and

a processor in communication with the sensor that controls the first valve's open or closed position based at least in part upon the temperature output by the sensor so that when the temperature of the fluid at the inlet port of the turbine is below a predefined threshold temperature, the processor causes the first valve to be in an open position;

wherein the first valve's open position directs fluid exiting from the heater and fluid exiting from the inlet of the turbine to the inlet port of the compressor when the temperature output by the sensor is below the predefined threshold temperature; and

wherein the fluid driving the turbine is a single-phase fluid.

2. The supercritical Brayton cycle power generation system of claim 1 , wherein the fluid is carbon dioxide.

3. The supercritical Brayton cycle power generation system of claim 1 , wherein the fluid is a refrigerant.

4. The supercritical Brayton cycle power generation system of claim 1 , wherein the shaft operatively couples the turbine with the compressor, and wherein the motor and the generator are comprised by a motor/generator unit.

5. The supercritical Brayton cycle power generation system of claim 1 , further comprising:

a re-compressor, wherein the motor is further operative to drive the re-compressor, and wherein the re-compressor comprises an inlet port and an outlet port.

6. The supercritical Brayton cycle power generation system of claim 5 , further comprising:

a third piping in fluid communication between the second piping and the inlet port of the re-compressor; and

a fourth piping in fluid communication between the outlet port of the re-compressor and the first piping;

a union in fluid communication between the first piping and the fourth piping; and

a second valve positioned on the second piping that is operative to direct the fluid in the second piping to flow into the compressor when the second valve is open;

a third valve positioned on the third piping that is operative to direct the fluid in the second piping to flow to the inlet of the re-compressor when the third valve is open;

wherein the third valve is controlled by the processor to be in an open position to cause fluid in the third piping to flow to the inlet of the re-compressor and by-pass the inlet port of the compressor if the temperature output by the sensor and received by the processor is below the predefined threshold temperature.

7. The supercritical Brayton cycle power generation system of claim 6 , further comprising:

a sixth piping in fluid communication between the second piping and the first piping;

a fourth valve positioned on the sixth piping that is operative to direct the fluid in the second piping to flow to the first piping when the fourth valve is open; and

a pump disposed on the sixth piping that is configured to pump the fluid through the heater and towards the inlet port of the turbine at startup of the supercritical Brayton cycle power generation system,

wherein the fourth valve is controlled by the processor to be in an open position to direct fluid in the second piping to flow to the first piping and by-pass the inlet port of the compressor if the temperature output by the sensor and received by the processor is below the predefined threshold temperature.

8. A method that facilitates a cold startup of a supercritical Brayton cycle power generation system, the supercritical Brayton cycle power generation system including a processor, a heater, a turbine, a sensor, a compressor, and a valve, the valve being in respective fluid communication with an output of the heater and an inlet port of the turbine and an inlet of the compressor, the sensor being disposed at the inlet port of the turbine, and the processor being respectively operatively coupled to the sensor and the valve, the method comprising:

heating fluid by the heater so as to increase a temperature of the fluid, the heated fluid being received at the inlet port of the turbine;

monitoring a temperature of the heated fluid at the inlet port of the turbine by the sensor;

comparing, by the processor, the monitored temperature with a predefined threshold temperature; and

changing the valve's open/close position, by the processor, from a closed position to an open position based on the comparison when the temperature of the fluid at the inlet port of the turbine is below the predefined threshold temperature so that the fluid output from the heater flows toward the valve and forms a combined fluid with fluid flowing from the inlet port of the turbine and the combined fluid flows through the valve to the inlet of the compressor,

wherein the fluid that drives the turbine is a single-phase fluid.

9. The method of claim 8 , wherein the fluid is carbon dioxide.

10. The method of claim 8 , wherein the at least one operating condition further includes a speed of a motor that is utilized to drive a compressor in the supercritical Brayton cycle power generation system.

11. The method of claim 8 , wherein the at least one operating condition further includes an amount of power provided to a pump that is configured to transport the fluid to the heater.