A heat recovery steam generation system is provided. The heat recovery steam generation system includes at least one superheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow. The system also includes an inter-stage attemperator for injecting an attemp
A heat recovery steam generation system is provided. The heat recovery steam generation system includes at least one superheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow. The system also includes an inter-stage attemperator for injecting an attemperation fluid into the steam path. The system further includes a control valve coupled to the inter-stage attemperator. The control valve is configured to control flow of attemperation fluid to the inter stage attemperator. The system also includes a controller coupled to the control valve and the inter-stage attemperator. The controller further includes a feedforward controller and a trimming feedback controller. The feedforward controller is configured to determine a desired amount of flow of the attemperation fluid and the trimming feedback controller is configured to compensate for inaccuracies in the determined amount of flow of the attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve into an inlet of the inter-stage attemperator based upon an outlet temperature of steam from the superheater. The controller also determines a control valve demand based upon the flow to valve characteristics. The controller further manipulates the control valve of the inter-stage attemperator, and injects the desired amount of attemperation flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater.
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1. A heat recovery steam generation system, comprising: at least one superheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow;an inter-stage attemperator for injecting an attemperation fluid into the steam path;a control valve coupled to the inter-sta
1. A heat recovery steam generation system, comprising: at least one superheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow;an inter-stage attemperator for injecting an attemperation fluid into the steam path;a control valve coupled to the inter-stage attemperator, the control valve configured to control flow of the attemperation fluid to the inter stage attemperator; anda controller comprising a feedforward controller configured to determine a desired amount of flow of the open loop attemperation fluid and a trimming feedback controller configured to compensate for inaccuracies in the determined amount of flow of the open loop attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve into an inlet of the inter-stage attemperator based upon an outlet temperature of steam from the superheater; wherein the controller is further configured to: determine a control valve demand based upon flow to valve characteristics;manipulate the control valve of the inter-stage attemperator, andinject the desired amount of flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater. 2. The heat recovery steam generation system of claim 1, wherein an evaporator in the steam path may be configured to deliver steam to the superheater. 3. The heat recovery steam generation system of claim 1, wherein a steam boiler drum in the steam path may be configured to deliver steam to the superheater. 4. The heat recovery steam generation system of claim 1, wherein the system may comprise a reheater in a steam path and configured to reheat the steam. 5. The heat recovery steam generation system of claim 1, wherein the superheater further comprises a primary superheater and a finishing superheater, both in the steam path and configured to superheat steam from the evaporator. 6. The heat recovery steam generation system of claim 5, wherein the inter-stage attemperator is in the steam path downstream of the primary superheater and upstream of the finishing superheater and configured to inject attemperation fluid into the steam path. 7. The heat recovery steam generation system of claim 1, wherein the control valve demand is determined based upon the flow demand, valve coefficient, density and change in pressure across the control valve. 8. The heat recovery steam generation system of claim 1, further comprising an anti-quench controller configured to maintain steam temperature at inlet of the superheater above a saturation temperature. 9. The heat recovery steam generation system of claim 8, wherein the anti-quench controller is decoupled from the controller. 10. A method for controlling outlet temperatures of steam from a finishing superheater of a heat recovery steam generation system, comprising: determining a desired amount of flow of an open loop attemperation fluid via a feedforward controller;compensating for inaccuracies in the determined amount of flow of the open loop attemperation fluid via a trimming feedback controller;determining a net desired amount of flow of attemperation fluid through a control valve into an inlet of an inter-stage attemperator based upon an outlet temperature of steam from a finishing superheater of a heat recovery steam generation system;determining a control valve demand based upon flow to valve characteristics; manipulating the control valve of the inter-stage attemperator; andinjecting the desired amount of flow of attemperation fluid to perform attemperation upstream of an inlet into the finishing superheater. 11. The method of claim 10, comprising determining inlet variables at the inlet into the finishing superheater, wherein a model-based predictive temperature control is configured to predict the outlet temperature of the steam based on the inlet variables. 12. The method of claim 10, wherein performing attemperation comprises opening a control valve upstream of the inlet into the finishing superheater, wherein opening the control valve introduces attemperation fluid into a path with the steam, and the attemperation fluid is cooler than the steam. 13. The method of claim 10, wherein attemperation is performed only if the inlet temperature of the steam into the finishing superheater is greater than a saturation temperature of steam by a pre-determined safety value. 14. A controller comprising a feedforward controller configured to determine a desired amount of flow of the open loop attemperation fluid and a trimming feedback controller configured to compensate for inaccuracies in the determined amount of flow of the open loop attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve into an inlet of the inter-stage attemperator based upon an outlet temperature of steam from the superheater; wherein the controller is further configured to: determine a control valve demand based upon flow to valve characteristics;manipulate the control valve of the inter-stage attemperator, andinject the desired amount of flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater. 15. The controller of claim 14, wherein the controller is configured to bypass attemperation whenever an inlet temperature of steam into the superheater does not exceed a saturation temperature of steam by a pre-determined safety value. 16. The controller of claim 14, wherein the controller is at least partially based on input variables comprising an inlet temperature of a flue gas into the superheater, an inlet pressure of steam or flue gas into the superheater, an inlet flow rate of steam or flue gas into the superheater, valve coefficient, density, inlet attemperator pressure, inlet attemperator temperature or a combination thereof. 17. The controller of claim 14, wherein the controller has a model-based predictive temperature control logic comprising an empirical data-based model, a thermodynamic-based model, or a combination thereof. 18. The controller of claim 17, wherein the model-based predictive temperature control logic comprises a proportional-integral controller configured to compensate for inaccuracies in a predictive temperature model. 19. The controller of claim 14, wherein the control loop comprises a linearization function block for operation of the control valve. 20. The controller of claim 14, wherein the control valve demand is determined based upon the flow demand, valve coefficient, density and change in pressure across the control valve.
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이 특허에 인용된 특허 (10)
William G. Gorman ; William George Carberg ; Charles Michael Jones, Apparatus and methods for supplying auxiliary steam in a combined cycle system.
Martens Alan (Berwyn PA) Myers Gerald A. (Swarthmore PA) McCarty William L. (West Chester PA) Wescott Kermit R. (Kennett Square PA), Heat recovery steam generator outlet temperature control system for a combined cycle power plant.
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