Method and apparatus for controlling the final feedwater temperature of a regenerative rankine cycle
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
F01K-007/34
F01K-007/00
출원번호
US-0204898
(2005-08-16)
발명자
/ 주소
Lang,Fred D.
출원인 / 주소
Lang,Fred D.
인용정보
피인용 횟수 :
12인용 특허 :
3
초록▼
This invention relates to a method and apparatus for controlling the final feedwater temperature associated with a regenerative Rankine cycle, said cycle commonly used in thermal systems such as conventional power plants. This invention involves the placement of a new heat exchanger, termed an Exerg
This invention relates to a method and apparatus for controlling the final feedwater temperature associated with a regenerative Rankine cycle, said cycle commonly used in thermal systems such as conventional power plants. This invention involves the placement of a new heat exchanger, termed an Exergetic Heater, in the feedwater path downstream from the highest pressure feedwater heater to assure that the feedwater is properly heated to its final temperature before entering the steam generator. The heating of the feedwater is accomplished by routing steam from the Intermediate Pressure turbine, which normally is routed to the second highest pressure heater. Control of the final feedwater temperature is achieved through a control valve whose actuation adjusts the amount of steam flow being routed from the Intermediate Pressure turbine to the Exergetic Heater.
대표청구항▼
What is claimed is: 1. A method for quantifying the operation of a thermal system in which a final feedwater temperature is to be controlled, the thermal system consisting of a steam generator and a regenerative Rankine cycle having an Intermediate Pressure turbine and a feedwater path, the method
What is claimed is: 1. A method for quantifying the operation of a thermal system in which a final feedwater temperature is to be controlled, the thermal system consisting of a steam generator and a regenerative Rankine cycle having an Intermediate Pressure turbine and a feedwater path, the method comprising the steps of: installing a heat exchanger in the feedwater path upstream from the steam generator, resulting in an Exergetic Heater; routing a source of working fluid from the Intermediate Pressure turbine, applicable for feedwater heating, to the Exergetic Heater; and controlling the final feedwater temperature by adjusting the source of working fluid from the Intermediate Pressure turbine. 2. The method of claim 1, wherein in step of controlling the final feedwater temperature includes the steps of: obtaining a final feedwater temperature set-point; controlling the final feedwater temperature by adjusting the source of working fluid such that the final feedwater temperature set-point is reasonably achieved. 3. The method of claim 2, wherein the step of obtaining the final feedwater temperature set-point includes the step of: obtaining the final feedwater temperature set-point which is a function of power output produced by the thermal system. 4. The method of claim 2, wherein the step of obtaining the final feedwater temperature set-point includes the steps of: determining a boiler efficiency applicable to the steam generator; optimizing the boiler efficiency by varying the final feedwater temperature set-point until a maximum value of the boiler efficiency is achieved, resulting in the final feedwater temperature set-point which is optimized. 5. The method of claim 2, wherein the step of obtaining the final feedwater temperature set-point includes the steps of: determining a boiler efficiency applicable to the steam generator; determining a turbine cycle efficiency applicable to the regenerative Rankine cycle; determining a system thermal efficiency based on the boiler efficiency and the turbine cycle efficiency; and optimizing the system thermal efficiency by varying the final feedwater temperature set-point until a maximum value of the system thermal efficiency is achieved, resulting in the final feedwater temperature set-point which is optimized. 6. The method of claim 1, including after the step of controlling the final feedwater temperature, the additional step of: routing an outlet shell-side fluid from the Exergetic Heater to a feedwater heater. 7. The method of claim 1, including after the step of controlling the final feedwater temperature, the additional step of: routing an outlet shell-side fluid from the Exergetic Heater based on the available pressure head required for draining the outlet shell-side fluid from the Exergetic Heater. 8. The method of claim 1, including after the step of controlling the final feedwater temperature, the additional steps of: installing a diffuser intended to deliver an outlet shell-side fluid from the Exergetic Heater at a higher pressure; routing a motive working fluid from the thermal system to the diffuser; and routing the outlet shell-side fluid from the Exergetic Heater through the diffuser, operated by the motive working fluid, to a higher pressure. 9. The method of claim 4, wherein the step of determining the boiler efficiency applicable to the steam generator includes the step of: determining the boiler efficiency applicable to the steam generator based on a procedure selected from the group comprising an Input/Loss Method, an ASME PTC 4 Method, an ASME PTC 4.1 Method, a DIN 1942 Method, a Control-Oriented Method and a DCS-Based Method. 10. The method of claim 5, wherein the step of determining the boiler efficiency applicable to the steam generator includes the step of: determining the boiler efficiency applicable to the steam generator based on a procedure selected from the group comprising an Input/Loss Method, an ASME PTC 4 Method, an ASME PTC 4.1 Method, a DIN 1942 Method, a Control-Oriented Method and a DCS-Based Method. 11. A device for a thermal system in which a final feedwater temperature is to be controlled, said thermal system consisting of a steam generator and a regenerative Rankine cycle having an Intermediate Pressure turbine and a feedwater path, the device comprising: a heat exchanger installed in the feedwater path of the regenerative Rankine cycle and before the steam generator with a means of feedwater heating, resulting in an installed Exergetic Heater; an instrument for measuring a final feedwater temperature between the installed Exergetic Heater and the steam generator, having an output final feedwater temperature signal; a control valve having an inlet connection and an outlet connection; a pipe carrying fluid from the Intermediate Pressure turbine to the inlet connection of the control valve; and a pipe carrying fluid from the outlet connection of the control valve to the installed Exergetic Heater; and a control device for controlling the final feedwater temperature having as an input signal the output final feedwater temperature signal, and having an output signal which actuates the control valve such that the final feedwater temperature is controlled. 12. The device of claim 11 wherein the heat exchanger installed in the feedwater path, also comprises: a heat exchanger having a shell-side and tube-side configuration installed in the feedwater path of the regenerative Rankine cycle and before the steam generator with a means of feedwater heating, resulting in an installed Exergetic Heater. 13. The device of claim 11 wherein the instrument for measuring the final feedwater temperature includes: a Resistance Temperature Detector instrument, also termed RTD, for measuring a final feedwater temperature between the installed Exergetic Heater and the steam generator, having an output final feedwater temperature signal. 14. The device of claim 11 wherein the instrument for measuring the final feedwater temperature includes: a thermocouple instrument for measuring a final feedwater temperature between the installed Exergetic Hater and the steam generator, having an output final feedwater temperature signal. 15. The device of claim 11 wherein the control device for controlling the final feedwater temperature includes: a means to determine boiler efficiency, having an output boiler efficiency signal; the control device for controlling the final feedwater temperature having as input signals the output final feedwater temperature signal and the output boiler efficiency signal, and having an output signal which actuates the control valve such that the final feedwater temperature is controlled. 16. The device of claim 11 wherein the control device for controlling the final feedwater temperature includes: a Proportional Integral Derivative controller device, also termed PID, for controlling the final feedwater temperature having as an input signal the output final feedwater temperature signal, and having an output signal which actuates the control valve such that the final feedwater temperature is controlled. 17. The device of claim 11 wherein the control device for controlling the final feedwater temperature includes: a pneumatic control device for controlling the final feedwater temperature having as an input signal the output final feedwater temperature signal, and having an output signal which actuates the control valve such that the final feedwater temperature is controlled. 18. A method for quantifying the operation of a thermal system in which a final feedwater temperature is to be controlled, the thermal system consisting of a steam generator and a regenerative Rankine cycle having an Intermediate Pressure turbine and a feedwater path carrying a flow of feedwater, the method comprising the steps of: installing a heat exchanger having a shell-side and a tube-side in the feedwater path of the regenerative Rankine cycle and upstream from the steam generator, resulting in an Exergetic Heater; obtaining a final feedwater temperature associated with optimum operation of the steam generator, resulting in an optimized final feedwater temperature; routing an extraction steam source from the Intermediate Pressure turbine to the shell-side of the Exergetic Heater; routing the flow of feedwater to the tube-side of the Exergetic Heater; and controlling the extraction steam source such that the optimized final feedwater temperature is achieved.
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이 특허에 인용된 특허 (3)
Termuehlen Heinz (Sarasota FL) Saddler Jerry (St. Louis MO) Brueckner Hermann (Uttenreuth DEX) Bergmann Dietmar (Mulheim an der Ruhr DEX), Gas turbine topped steam plant.
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