Control system for a heat engine system utilizing supercritical working fluid

Abstract

A heat engine system and a method for generating electrical energy from the heat engine system are provided. The method includes circulating via a turbo pump a working fluid within a working fluid circuit of the heat engine system. The method also includes transferring thermal energy from a heat source stream to the working fluid by at least a primary heat exchanger, feeding the working fluid into a power turbine and converting the thermal energy from the working fluid to mechanical energy, and converting the mechanical energy into electrical energy by a generator coupled to the power turbine. At least one valve operatively coupled to a control system is modulated in order to synchronize the generator with an electrical grid. A generator breaker is closed such that the generator and electrical grid are electrically coupled and the electrical energy is supplied to the electrical grid.

1 . A method for synchronizing a generator of a heat engine system with an electrical grid, comprising:
 circulating, via a turbo pump, a working fluid within a working fluid circuit of the heat engine system, wherein the working fluid circuit has a high pressure side and a low pressure side and at least a portion of the working fluid is in a supercritical state;   transferring thermal energy from a heat source stream to the working fluid by at least a primary heat exchanger fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit;   feeding the working fluid into a power turbine and converting the thermal energy from the working fluid to mechanical energy of the power turbine;   converting the mechanical energy into electrical energy by the generator coupled to the power turbine;   comparing at least one electrical energy parameter of the electrical energy converted by the generator with at least one grid parameter of the electrical grid configured to be electrically coupled to the generator; and   modulating at least one valve of a plurality of valves operatively coupled to a process control system to change a flow rate of the working fluid fed into the power turbine, such that the at least one electrical energy parameter of the electrical energy converted by the generator is substantially similar to the at least one grid parameter of the electrical grid, thereby synchronizing the generator with the electrical grid.   
     
     
         2 . The method of  claim 1 , wherein the plurality of valves comprises at least one valve selected from a power turbine trim valve, a power turbine throttle valve, a power turbine bypass valve, a drive turbine throttle valve, a turbo pump bypass valve, or combinations of valves thereof. 
     
     
         3 . The method of  claim 1 , wherein the at least one electrical energy parameter is selected from the group consisting of voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         4 . The method of  claim 1 , wherein the at least one grid parameter is selected from the group consisting of voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         5 . The method of  claim 1 , wherein the heat engine system comprises a plurality of sensors, at least one sensor of the plurality of sensors being disposed adjacent each of the plurality of valves and further being operatively coupled to the process control system and configured to detect at least one system parameter. 
     
     
         6 . The method of  claim 5 , further comprising transmitting from the at least one sensor a sensor signal based on the at least one system parameter to the process control system. 
     
     
         7 . The method of  claim 6 , wherein the process control system includes at least one controller including a ramp profile algorithm, such that the at least one controller is configured to manipulate the at least one valve to a predetermined valve position over a predetermined time period based on at least one of the sensor signals. 
     
     
         8 . The method of  claim 1 , wherein the at least one valve is a power turbine trim valve, a power turbine bypass valve, a drive turbine throttle valve, and a turbo pump bypass valve. 
     
     
         9 . The method of  claim 1 , wherein the working fluid comprises carbon dioxide. 
     
     
         10 . A method for generating electrical energy for an electrical grid with a heat engine system comprising a power generator, comprising:
 synchronizing the power generator with the electrical grid in accordance with the method of  claim 1 ;   closing a generator breaker, thereby electrically coupling the power generator and the electrical grid; and   feeding the electrical energy generated by the power generator to the electrical grid.   
     
     
         11 . The method of  claim 10 , wherein the at least one valve is a power turbine trim valve, a power turbine throttle valve, a power turbine bypass valve, a drive turbine throttle valve, a turbo pump bypass valve, or combinations of valves thereof. 
     
     
         12 . The method of  claim 11 , wherein the at least one electrical energy parameter is selected from the group consisting of voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         13 . The method of  claim 12 , wherein the at least one grid parameter is selected from the group consisting of voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         14 . A method for supplying electrical energy to an electrical grid from a heat engine system, comprising:
 circulating via a turbo pump a working fluid within a working fluid circuit of the heat engine system, wherein the working fluid circuit has a high pressure side and a low pressure side and at least a portion of the working fluid is in a supercritical state;   transferring thermal energy from a heat source stream to the working fluid by at least a primary heat exchanger fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit;   feeding the working fluid into a power turbine and converting the thermal energy from the working fluid to mechanical energy of the power turbine;   converting the mechanical energy into electrical energy by a power generator coupled to the power turbine;   comparing a plurality of electrical energy parameters of the electrical energy converted by the power generator with a plurality of grid parameters of the electrical grid configured to be electrically coupled to the power generator;   modulating at least one valve selected from a power turbine trim valve, a power turbine throttle valve, a power turbine bypass valve, a drive turbine throttle valve, a turbo pump bypass valve, or combinations of valves thereof, each operatively coupled to a process control system to change a flow rate of the working fluid fed into the power turbine, such that the a plurality of electrical energy parameters of the electrical energy converted by the power generator is substantially similar to the plurality of grid parameters of the electrical grid, thereby synchronizing the power generator with the electrical grid; and   closing the generator breaker, such that the power generator and electrical grid are electrically coupled and the electrical energy is supplied to the electrical grid.   
     
     
         15 . The method of  claim 14 , wherein the plurality of electrical energy parameters includes voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         16 . The method of  claim 14 , wherein the plurality of grid parameters includes voltage, phase sequence, phase angle, waveform, and frequency. 
     
     
         17 . The method of  claim 14 , wherein the heat engine system comprises a plurality of sensors, at least one sensor of the plurality of sensors being disposed adjacent each of the power turbine trim valve, the power turbine throttle valve, the power turbine bypass valve, the turbo pump bypass valve, and the drive turbine throttle valve, and further being operatively coupled to the process control system and configured to detect at least one system parameter, and the method further comprises transmitting from the at least one sensor a sensor signal based on the at least one system parameter to the process control system. 
     
     
         18 . The method of  claim 17 , wherein the process control system includes at least one controller including a ramp profile algorithm, such that the at least one controller is configured to manipulate one or more of the power turbine trim valve, the power turbine throttle valve, the power turbine bypass valve, the turbo pump bypass valve, and the drive turbine throttle valve to a predetermined valve position over a predetermined time period based on at least one of the sensor signals. 
     
     
         19 . The method of  claim 14 , wherein the working fluid comprises carbon dioxide. 
     
     
         20 . A method for supplying electrical energy to an electrical grid from a heat engine system, comprising:
 starting a drive turbine from a working fluid including carbon dioxide being circulated via a start pump within a working fluid circuit of the heat engine system;   circulating via a turbo pump coupled to the drive turbine the working fluid within the working fluid circuit of the heat engine system, wherein the working fluid circuit has a high pressure side and a low pressure side and at least a portion of the working fluid is in a supercritical state;   transferring thermal energy from a heat source stream to the working fluid by at least a primary heat exchanger fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit;   feeding the working fluid into a power turbine and converting the thermal energy from the working fluid to mechanical energy of the power turbine;   converting the mechanical energy into electrical energy by a power generator coupled to the power turbine;   comparing a plurality of electrical energy parameters of the electrical energy converted by the power generator with a plurality of grid parameters of the electrical grid configured to be electrically coupled to the power generator, wherein
 the plurality of electrical energy parameters includes voltage, phase sequence, phase angle, waveform, and frequency; and 
 the plurality of grid parameters includes voltage, phase sequence, phase angle, waveform, and frequency; 
   modulating a power turbine trim valve, a power turbine throttle valve, a power turbine bypass valve, a turbo pump bypass valve, a drive turbine throttle valve, or combinations of valves thereof, each operatively coupled to a process control system to change a flow rate of the working fluid fed into the power turbine, such that the plurality of electrical energy parameters of the electrical energy converted by the power generator is substantially similar to the plurality of grid parameters of the electrical grid, thereby synchronizing the power generator with the electrical grid; and   closing the generator breaker, such that the power generator and electrical grid are electrically coupled and the electrical energy is supplied to the electrical grid.