Control of rotor stresses in turbomachinery during start-up operations.

Abstract

To provide a method, a program product and a system for controlling a rotor stress within each component of a turbomachine.SOLUTION: Embodiments of the disclosure provide a method for controlling a turbine during startup. The method includes calculating predicted stress on a rotor (26) of a turbine component (48), and determining whether the predicted stress exceeds a threshold. If the predicted stress exceeds the threshold, an inlet valve (104) is adjusted to a warming position, which is less open than a minimum load position. When steam in a discharge passage (112) reaches a target pressure, an exhaust valve (110) partially closes. If a safety parameter of the turbine component (48) violates a boundary, the exhaust valve (110) partially opens while the inlet valve (104) is kept in the warming position. The predicted stress on the rotor (26) is recalculated with the inlet valve (104) being in the warming position. When the predicted stress does not exceed the threshold, the inlet valve (104) opens to at least the minimum load position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates generally to the operation of turbomachines. More specifically, embodiments of the present disclosure provide a methodology for controlling rotor stresses within portions of a turbine system during startup operations when the turbomachine may experience backpressure on or within turbine elements. [Background technology]

[0002] A power generation system, also known as a power plant, typically includes a variety of different systems (e.g., turbomachinery, generators, and / or other interconnected assemblies) used to generate an electrical power output. Such a power generation plant may include a power source (e.g., turbomachinery, solar panels, nuclear reactor, etc.), a prime mover (e.g., a rotatable shaft or similar element) for coupling the power source to the generator, and / or various components of the generator. For example, a power generation system may include a gas turbine assembly having a compressor coupled to the gas turbine. The gas turbine may then be coupled to and drive a generator mounted on the same shaft. The generator produces the electrical power output.

[0003] Power generation systems typically include a variety of different turbomachines and / or systems used to generate electrical power output. Examples of such power systems may include gas turbine systems and / or combined cycle power plants, which typically include one or more gas turbine systems. Conventional combined cycle power plants employ one or more gas turbine systems operably coupled to one or more steam turbine systems. The gas turbine system includes a compressor coupled to the gas turbine. The gas turbine is typically coupled to and drives external components, such as an electric generator, to generate a load or electrical power output. The steam turbine system typically includes a high-pressure (HP) turbine section operably coupled to an intermediate-pressure (IP) turbine section, which is coupled to a low-pressure (LP) turbine. Like the gas turbine of a gas turbine system, the HP, IP, and LP turbines are used to drive external components (e.g., electric generators).

[0004] In a typical combined cycle power plant, exhaust gases from the gas turbine are routed to a heat recovery steam generator (HRSG), which reheats and provides steam for various turbine sections of a steam turbine system, which may be used to increase the efficiency of the system and / or power plant. Downstream of the HRSG, the exhaust gases are vented to the atmosphere through a stack. A technical challenge associated with steam turbine (ST) operation is ensuring safe and reliable operation of steam turbine components during start-up and maintaining various parameters within target boundaries. Temperature and pressure increases from non-operating values ​​throughout the turbine can affect the health and lifespan of ST components in addition to affecting the power output from the ST system. Summary of the Invention

[0005] An aspect of the disclosure is a method for controlling steam pressure within a turbine component during start-up operations, the turbine component being fluidly coupled between an inlet having an inlet valve for controlling steam flow to the turbine component and an exhaust having an exhaust valve for controlling steam flow to an exhaust passage, the method including: adjusting the exhaust valve to a fully open position and adjusting the inlet valve to a fully closed position; calculating predicted stresses on a rotor of the turbine component based on a predicted steam flow with the inlet valve in a minimum load position, a rotor surface temperature, and an inlet steam temperature; determining whether the predicted stresses exceed a threshold; and, in response to the predicted stresses exceeding the threshold, controlling steam flow through the turbine component to flow through the exhaust passage. adjusting the inlet valve to a warmed position not more open than the minimum load position to pressurize; partially closing the exhaust valve while maintaining the inlet valve in the warmed position in response to steam in the exhaust passage reaching a target pressure; determining whether a turbine component safety parameter violates a boundary while maintaining the inlet valve in the warmed position; in response to the turbine component safety parameter violating the boundary, partially opening the exhaust valve while maintaining the inlet valve in the warmed position; recalculating predicted stresses on the rotor with the inlet valve in the warmed position; and in response to the predicted stresses not exceeding a threshold, opening the inlet valve to at least the minimum load position.

[0006] A further aspect of the present disclosure is a program product stored on a computer readable storage medium for controlling steam pressure in a turbine component during start-up operations, the turbine component being fluidly coupled between an inlet having an inlet valve for controlling steam flow to the turbine component and an exhaust having an exhaust valve for controlling steam flow to an exhaust passage, the computer readable storage medium causing a computer system to: adjust the exhaust valve to a fully open position and adjust the inlet valve to a fully closed position; calculate predicted stresses on a rotor of the turbine component based on a predicted steam flow with the inlet valve in a minimum load position, a rotor surface temperature, and an inlet steam temperature; determine whether the predicted stresses exceed a threshold; and, in response to the predicted stresses exceeding the threshold, control steam pressure through the turbine component. A program product is provided, the program product including program code for performing actions including adjusting an inlet valve to a warmed position less open than the minimum load position so that steam flow pressurizes the exhaust passage; partially closing an exhaust valve while maintaining the inlet valve warmed position in response to steam in the exhaust passage reaching a target pressure; determining whether a turbine component safety parameter violates a boundary while maintaining the inlet valve warmed position; in response to the turbine component safety parameter violating the boundary, partially opening the exhaust valve while maintaining the inlet valve warmed position; recalculating predicted stresses on the rotor with the inlet valve in the warmed position; and in response to the predicted stresses not exceeding a threshold, opening the inlet valve to at least the minimum load position.

[0007] An additional aspect of the present disclosure is a turbine component fluidly coupled between an inlet having an inlet valve for controlling steam flow into the turbine component and an exhaust having an exhaust valve for controlling steam flow to an exhaust passage; and a control system operatively coupled to the inlet valve and the exhaust valve of the turbine component, the control system adjusting the exhaust valve to a fully open position and adjusting the inlet valve to a fully closed position; calculating predicted stresses on a rotor of the turbine component based on a predicted steam flow with the inlet valve in a minimum load position, a rotor surface temperature, and an inlet steam temperature; determining whether the predicted stresses exceed a threshold; and, in response to the predicted stresses exceeding the threshold, controlling the steam flow through the turbine component to stress the exhaust passage. and a control system that implements actions including adjusting the inlet valve to a warmed position not more open than the minimum load position to increase steam pressure in the exhaust passage; partially closing the exhaust valve while maintaining the inlet valve in the warmed position in response to steam in the exhaust passage reaching the target pressure; determining whether a turbine component safety parameter violates a boundary while maintaining the inlet valve in the warmed position; and in response to the turbine component safety parameter violating the boundary, partially opening the exhaust valve while maintaining the inlet valve in the warmed position; recalculating predicted stresses on the rotor with the inlet valve in the warmed position; and in response to the predicted stresses not exceeding a threshold, opening the inlet valve to at least the minimum load position.

[0008] The exemplary aspects of the present disclosure are designed to solve the problems described herein and / or other problems not discussed.

[0009] These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure, taken in conjunction with the accompanying drawings which illustrate various embodiments of the present disclosure. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a control system, a combined cycle power generation system, and other components configured for use in a method according to an embodiment of the present disclosure. [Figure 2] 1 is an enlarged schematic view of portions of a control system and turbomachinery in the form of a steam turbine (ST) system according to an embodiment of the present disclosure. FIG. [Figure 3] FIG. 1 illustrates an exemplary environment of control systems and sub-components configured to interact with portions of a turbomachine according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is an exemplary flow diagram of a method for controlling steam temperature in a turbomachine during startup operations in accordance with an embodiment of the present disclosure. [Figure 5] FIG. 2 is an expanded flow diagram of a process for controlling steam temperature in a turbomachine during startup operations in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] It should be noted that the drawings of the present disclosure are not to scale. The drawings are intended to illustrate only typical aspects of the present disclosure and therefore should not be considered limiting of the scope of the present disclosure. In the drawings, like numbers represent like elements between the drawings.

[0012] As an initial matter, a clear description of the state of the art necessitates the selection of specific terminology when referring to and describing the various systems, components, and related machine components within other embodiments of the present disclosure. Wherever possible, common industry terminology is used and utilized consistent with its accepted meaning. Unless otherwise noted, such terminology should be given a broad interpretation consistent with the context of this application and the scope of the appended claims. Those skilled in the art will recognize that in many cases, a particular component may be referred to using several different or overlapping terms. What may be described herein as a single component may include and be referred to in other contexts as consisting of multiple components. Alternatively, what may be described herein as comprising multiple components may be referred to elsewhere as a single component.

[0013] Additionally, as noted below, certain descriptive terms may be used herein in a conventional manner: the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another, and are not intended to denote the location or importance of the individual components.

[0014] The terminology used herein is merely for the purpose of describing particular embodiments and is not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless expressly stated otherwise. It will be further understood that the terms "comprise" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or sets thereof. "Optional" or "optionally" means that the subsequently-stated event or circumstance may or may not occur, and the description is meant to include instances in which the event occurs and instances in which it does not occur.

[0015] When an element or layer is referred to as "on," "engaged," "connected," or "coupled" to another element or layer, it can be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. Conversely, when an element is referred to as "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may not be intervening elements or layers. Other terms used to describe relationships between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0016] Embodiments of the present disclosure provide methods, program products, and systems for controlling rotor stresses within portions of turbomachinery. According to one example, the present disclosure can be useful for managing high-pressure (HP) components of a steam turbine (ST) system during startup operations. In one such example, the present disclosure provides a methodology for operating an ST system having an HP component fluidly coupled between an inlet having an inlet valve for controlling steam flow to the HP component and an exhaust having an exhaust valve for controlling steam flow from the HP component to a condenser. During startup operations, steam can flow through an intermediate-pressure (IP) and / or low-pressure (LP) section of the ST system until conditions are met and the steam enters the HP component. Embodiments of the present disclosure predict the amount of stress the initial steam flow will impart to the rotor. If the predicted stress is too high, the methodology can direct steam flow below minimum load to warm the turbine (e.g., in one example, within the HP component) and pressurize the fluidly interconnected components.

[0017] In an embodiment of the present disclosure, a turbomachine operator may initially adjust the exhaust valve to a fully open position and the inlet valve to a fully closed position. In this state, steam does not flow through the turbine components of the turbomachine, but existing fluid can pass through the exhaust valve. The method then includes calculating a predicted stress on the rotor of the turbomachine. The "predicted stress" refers to the stress imparted to the rotor at the moment when minimum operating steam flow begins to pass through the turbine components. The predicted steam flow is therefore based on measurements of the rotor surface temperature and inlet steam temperature, as well as the inlet valve in a minimum load position. If the predicted stress exceeds a stress threshold (hereinafter simply referred to as the "threshold"), the inlet valve is adjusted to a "warming position," which is more open than the minimum load position but not fully closed. In this state, the steam flow can pressurize the condenser discharge passage, driving rotor rotation and generating power output. When the steam in the discharge passage reaches a target pressure, the exhaust valve position is reduced, while the inlet valve remains in the warming position. At this point, the turbine components begin to pressurize, accelerating the warming of the turbine elements. During warm-up of the turbine components, one or more safety parameters can be monitored, and the exhaust valve can be partially opened to prevent violation of the safety parameter boundaries. The predicted stresses for the minimum load position are then recalculated, with the inlet valve still in the warm-up position, until they are below a threshold. Once the predicted stresses are below the threshold, the inlet valve opens to at least the minimum load position, and the exhaust valve closes fully. In some embodiments, the resulting stresses on the rotor are input into a predictive model that adjusts future calculations of predicted stresses. These adjusted calculations of predicted stresses can affect the opening and closing of the inlet and exhaust valves in future start-up operations.

[0018] These and other embodiments are described below with reference to Figures 1-5. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for illustrative purposes only and should not be construed as limiting.

[0019] FIG. 1 illustrates a schematic diagram of a system 10 according to various embodiments of the present disclosure. In an exemplary implementation, the system 10 may include a combined cycle power generation system 12 (hereinafter, “power generation system 12”) including a steam turbine (ST) system 18, which, in the illustrated diagram, may include a low-pressure (LP) component 20, an intermediate-pressure (IP) component 22, and a high-pressure (HP) component 24, as known in the art. The LP component 20, the IP component 22, and the HP component 24 of the ST system 18 may all be coupled and / or positioned and / or configured to rotate a rotor 26 to generate mechanical work and / or drive additional components of the ST system 18. The various components of the system 10 need not be attached to only one rotor 26, but may also be attached to and / or operably coupled to multiple respective rotors. As illustrated in FIG. 1 , the rotor 26 of the ST system 18 may be coupled to and / or drive external components, more specifically, a generator 28 configured to generate electricity and / or generate an electrical load. Although system 10 is shown and described as a combined cycle power generation system having multiple rotors and / or generators 26, 28, it is understood that system 10 may include only an ST system 18, only one rotor 26, and / or any other now known or later developed type of ST system and / or configuration.

[0020] The power generation system 12 may further include a gas turbine (GT) system 30. The GT system 30 may include a compressor 32. The compressor 32 compresses an incoming flow of fluid 34 (e.g., air) flowing therethrough. The compressor 32 may include multiple stages of stator vanes (not shown) and rotating blades (not shown) positioned therein. The stator vanes and rotating blades positioned therein may be configured to assist in moving and / or passing the fluid 34 through the compressor 32. The compressor 32 delivers a flow of compressed fluid 38 (e.g., compressed air) to a combustor 40. The combustor 40 mixes the flow of compressed fluid 38 with a pressurized flow of fuel 42 provided by a fuel supply 44 and ignites the mixture to generate a flow of combustion gases 46. The flow of combustion gases 46 is then delivered to turbine components 48, which, like the compressor 32, typically include multiple stages of stator vanes (not shown) and turbine blades (not shown). The flow of combustion gases 46 drives a turbine component 48 to generate mechanical work. The mechanical work generated by the turbine component 48 drives the compressor 32 via a shaft 50, which can be used to drive a generator 52 (e.g., an external component) configured to generate electrical power and / or generate a load.

[0021] 1 as including a dual shaft configuration in which two separate generators 28, 52 are used, it is understood that in other non-limiting examples, the ST system 18 and the GT system 30 may share a single shaft and in turn share a single generator. Additionally, while the power generation system 12 is shown as including only a single ST system 18 and a single GT system 30, it is understood that the power generation system 12 may include multiple ST systems 18 and / or GT systems 30 that can be configured to generate an operating load and / or power output.

[0022] The power generation system 12 may further include a heat recovery steam generator (HRSG) 54 in fluid communication with the ST system 18 (e.g., the HP component 24, the IP component 22, and / or the LP component 20) and the GT system 30. As shown in the non-limiting example of FIG. 1 , the HRSG 54 may be fluidly connected and / or coupled to the ST system 18 to receive exhaust fluid (e.g., steam) from the ST system 18 and may be coupled via a supply conduit 58 to provide steam to portions of the ST system 18 via the supply conduit 58. Additionally, in the non-limiting example of FIG. 1 , the HRSG 54 may be fluidly connected and / or coupled to the GT system 30 via an exhaust channel 59 coupled to and / or in fluid communication with the turbine component 48. The exhaust channel 59 provides exhaust fluid 60 (e.g., gas) from the GT system 30 to the HRSG 54, which may be utilized in generating and / or heating steam for the ST system 18. The stack 61 of the HRSG 54 may exhaust or vent (excess or spent) gases (e.g., exhaust fluids 60 ) and / or fluids from the HRSG 54 to the atmosphere and / or outside the power generation system 12 .

[0023] The power generation system 12 may further include a condenser 62. The condenser 62 may be in fluid communication with and / or fluidly coupled to various components of the power generation system 12. In a non-limiting example, the condenser 62 may be fluidly connected and / or coupled to the LP component 20 of the ST system 18 via a steam exhaust duct 64. The condenser 62 may be configured to condense an exhaust stream and / or a bypass stream (not shown) from the ST system 18 and / or the HRSG 54 and provide a condensed fluid (e.g., condensed water) to the HRSG 54, as known in the art.

[0024] 1 , system 10 may include at least one computing device 66 configured to control power generation system 12 during any phase of operation, including startup operations (i.e., the period between an inactive state and operation at a target load when the power output from ST system 18 is transient). Computing device 66 may be wired and / or wirelessly connected to and / or in communication with power generation system 12 and its various components (e.g., ST system 18, GT system 30, and / or HRSG 54, etc.) via any suitable electronic and / or mechanical communication components or techniques. Computing device 66 and its various components described herein may be a single standalone system functioning separately from another power plant control system (e.g., computing device) (not shown) that may control and / or regulate the operation and / or functions of power generation system 12 and its various components (e.g., ST system 18, GT system 30, etc.). Alternatively, the computing device 66 and its components may be integrally formed within, in communication with, and / or formed as part of a larger power plant control system (not shown) that may control and / or coordinate the operation and / or function of the power generation system 12 and its various components (e.g., ST system 18, GT system 30, etc.).

[0025] In various embodiments, computing device 66 may include a control system 68 and one or more sensors 70, as described herein, to control the operation of power generation system 12. As described herein, control system 68 may control power generation system 12 and its various components to affect the operation of power generation system 12. For example, as described herein, control system 68 may use various types of data and / or operating characteristics of HP component 24 and / or other components of system 10 determined by sensors 70 to control the operation of system 10 and / or affect various attributes thereof. In some cases, control system 68 may generate and / or provide predictive models (e.g., predictive model 244 shown in FIG. 3 and described elsewhere herein) that use operating conditions and / or other characteristics of system 10 to predict how HP component 24 may respond to particular situations (e.g., may predict stresses on rotor 26). Additionally, embodiments of the present disclosure may adjust the predictive models based on measurements obtained by sensors 70, for example. Embodiments of the control system 68 may be configured or operated in part by an engineer, a computing device 66, and / or a combination of an engineer and a computing device 66. Where applicable, the predictive models of the control system 68 may include bias constants to intentionally overestimate the predicted stresses on the rotor 26. The bias constants may take the form of, for example, multipliers, a predetermined amount of stress added to a preliminary calculation, and / or other mathematical modifications to the initial output. In some implementations, embodiments of the present disclosure may include modifying the bias constants in future start-up operations (e.g., reducing the bias constants to reduce the amount of overestimation) to account for the behavior of the system 10 under certain conditions. The bias constants may be calculated from data obtained using sensors 70, pre-recorded data for multiple systems 10, and / or derived from these and / or other data sources.

[0026] 1 , computing device 66 may include and / or be in electrical and / or mechanical communication with sensors 70, as well as many other additional and / or intermediate components, such as valves, solenoids, actuators, converters, etc. (not shown) positioned throughout system 10. As shown in the non-limiting example of FIG. 1 and described herein, at least one sensor 70 of and / or connected to computing device 66 may be positioned within HP component 24 and / or one or more of its various subcomponents, as described elsewhere herein. The sensors 70 in communication with computing device 66 of system 10 may be any suitable sensors or devices configured to detect and / or determine data, information, and / or operating characteristics regarding power generation system 12 during operation. For example, as described herein, sensors 70 positioned within HRSG 54 of power generation system 12 may be any suitable sensors configured to detect and / or determine properties of the working fluid (e.g., steam, exhaust fluid 60). Such properties may include working fluid temperatures within portions and / or components of HP component 24, temperatures of turbine components such as HP component 24 of ST system 18, and / or steam flow measurements of steam flowing through all or portions of a turbine such as HP component 24. In non-limiting examples, sensor 70 may be configured as, without limitation, a thermometer, a thermistor, a thermocouple, and / or any other mechanical / electrical temperature sensor. In some cases, computing device 66 may aggregate multiple measurements (e.g., temperature, pressure, etc.) for multiple portions of ST system 18 and / or its subcomponents to obtain a temperature profile, pressure profile, stress profile, etc. for ST system 18 and / or any of its components (e.g., HP component 24).

[0027] Although two sensors 70 are shown, it is understood that system 10 may include a greater number of sensors 70 (e.g., as shown in FIG. 2 ) that may be configured to provide information or data regarding the temperature of the fluids and components contained within HP component 24 and / or fluid flow measurements to computing device 66, and specifically control system 68. The number of sensors 70 shown in FIG. 1 is merely exemplary and not limiting. Thus, system 10 may include a greater or lesser number of sensors 70 than is shown in FIG. 1 or other figures.

[0028] Figure 2 shows an expanded schematic view of the HP components 24 and interconnected portions of the system 10 shown in Figure 1. Specifically, Figure 2 shows a schematic view of the HP components 24, along with the inlet connections from the HRSG 54 and the outlet connections to the condenser 62. It is understood that similarly numbered and / or named components may function in a substantially similar manner. Redundant descriptions of these components, as well as illustrations of other components in the system 10, have been omitted solely for clarity.

[0029] FIG. 2 illustrates the HP component 24 of the ST system 18 mounted and mechanically coupled to a portion of the rotor 26, as described elsewhere herein. Steam output from the HRSG 54 can be in fluid communication with one supply conduit 58, which is coupled to an inlet 102 to the HP component 24 through an inlet valve 104. The inlet 102 can fluidly couple the supply conduit 58 to a bowl 106 within the HP component 24. The bowl 106 represents the interior portion of the HP component 24 upstream of the energy extraction elements (e.g., rotating blades) and is therefore the highest temperature and pressure region within the HP component 24 during operation. Steam can flow through the HP component 24, where the rotating blades extract thermal energy from the steam before delivering it to an outlet 108. The outlet 108 can include an outlet valve 110 adjustable to control fluid flow to an exhaust passage 112 toward the condenser 62. The exhaust passage 112 can take the form of any pressure-sensitive component for reducing steam pressure before reaching the condenser 62. According to one example, the discharge passage 112 may take the form of a "dump tube," i.e., a mechanical assembly welded to a steam pipe downstream of the outlet 108 that reduces steam pressure to condenser pressure. A check valve 114 may also be coupled to the outlet 108, for example, to route excess steam to a reheater or other heat transfer component (not shown). The check valve 114 may direct such excess steam from the outlet 108, allowing it to reheat steam flow elsewhere within the ST system 18 and / or HRSG 54. The check valve 114 may be configured to prevent any steam passing therethrough from returning to the outlet 108 (e.g., from backpressure) and, therefore, may be embodied as any now-known or later-developed valve structure for allowing fluid to flow in only one direction.

[0030] 2 and similarly described herein with respect to FIG. 1 , the computing device 66, and more specifically, the control system 68 of the computing device 66, may be operatively coupled to and / or in electronic communication with various components of the ST system 18. For example, the computing device 66, and more specifically, the control system 68 of the computing device 66, may be operatively coupled to and / or in electronic communication with the valves 104, 110 of the ST system 18. The control system 68 of the computing device 66 may be configured to actuate and / or control the operation of the valves 104, 110. The control system 68 may actuate and / or control adjust the positions of the valves 104, 110 to actively control steam flow through the HP component 24 during operation of the ST system 18, as described herein. The valves 104, 110 may be adjusted between positions such as a fully open position, a fully closed position, and one or more partially open positions. Such control of the valves 104, 110 using the computing device 66 and / or control system 68, and / or similar features, may be implemented via mechanical couplings, electrical couplings, and / or converters (collectively shown via phantom lines) between the computing device 66 and the valves 104, 110. Adjusting the position of the valves 104, 110 as described herein may affect the temperature and pressure of steam within the HP components 24 and control stresses on the rotor 26 and / or other properties during startup operations.

[0031] To aid in the operation and / or control of the valves 104, 110, the control system 68 can also use information obtained by sensors 70 positioned within portions of the ST system 18 and / or elsewhere in the system 10 ( FIG. 1 ). As described herein with respect to FIG. 1 , the system 10, including the various portions of the ST system 18, can include sensors 70 of the computing device 66 positioned therein. In the non-limiting example shown in FIG. 2 , the sensors 70 can be positioned within various portions of the ST system 18 to obtain various information and / or operating characteristics about the components of the HRSG 54. For example, the sensors 70 may be positioned within the supply conduit 58, the bowl 106 of the HP component 24, and / or the outlet 108. The sensors 70 can additionally or alternatively be positioned elsewhere within the ST system 18, such as on the surface of the rotor 26, in other portions of the HP component 24, in the exhaust passage 112, in the inlet 102 to the HP component 24, and / or at any other location where a property (e.g., fluid temperature, fluid pressure, surface temperature, velocity, etc.) is measured. Such sensors 70 may additionally or alternatively be distributed throughout other components of the system 10, e.g., the HRSG 54, the LP and / or IP components 20, 22 of the ST system 18, the generator 28, etc., to measure various properties (e.g., temperature, pressure, stress, etc.) of such components for use by the control system 68.

[0032] As described herein, sensors 70 positioned within system 10 ( FIG. 1 ) and / or ST system 18 can be configured to detect and / or determine fluid temperature, fluid pressure, mass flow rate, component temperature, component pressure, and / or other properties of the components and / or fluid flow. In the non-limiting example shown in FIG. 2 , various sensors 70 positioned within HP component 24 and / or interconnected components may determine steam properties or other properties (e.g., the temperature of rotor 26) within ST system 18. That is, sensors 70 can determine and / or detect fluid temperature, pressure, mass flow rate, etc., such as steam temperature, at multiple locations as the steam flows from supply conduit 58 to inlet 102, through HP component 24, and through outlet 108 into exhaust passage 112 and / or check valve 114. As described elsewhere herein, sensors 70 in the non-limiting example may be configured as, but not limited to, thermometers, thermistors, thermocouples, and / or any other mechanical / electrical temperature sensors. In various embodiments, the computing device 66 may represent data from the sensors 70 in the form of a "profile" for the ST system 18 and / or its components, i.e., values ​​of temperature, stress, etc. indexed by the sensors (these values ​​are measured by the sensors).

[0033] Additionally, in a non-limiting example, the sensors 70 may directly or indirectly measure mass flow (e.g., volumetric flow (cubic meters per second)) at the location where each sensor 70 is located. Additional sensors 70 in communication with the computing device 66 may be configured to detect or determine the duration of operation of the ST system 18 during a startup phase, measured relative to an initial state in which the ST system 18 is in an inactive or quiescent operating phase. The temperatures (e.g., steam, components), fluid flow measurements, and / or duration of operation detected by the various sensors 70 positioned within the ST system 18 may be provided to the computing device 66, and specifically, the control system 68. As described herein, using the detected and / or measured temperatures, fluid flow measurements, duration of operation, etc., the control system 68 may actuate and / or adjust the operation or position of the valves 104, 110 to predict stresses on the rotor 26 and prevent excessive steam flow through the HP components 24 when at its minimum load level.

[0034] It is understood that the number of sensors 70 shown in FIG. 2 as being positioned within the ST system 18 is merely exemplary. Accordingly, the computing device 66 may include a greater or lesser number of sensors 70 positioned within the ST system 18 to assist in controlling the steam flow through the HP component 24, as described herein. Additionally, while some of the multiple sensors 70 are not shown in communication with the computing device 66, it is understood that all of the sensors 70 shown in FIG. 2 are capable of communicating with the computing device 66 and / or providing the computing device 66 with sensed data regarding the operating characteristics of the components of the ST system 18, as described herein. Furthermore, while the computing device 66, control system 68, and sensors 70 are only shown in FIG. 2, it is understood that the computing device 66, control system 68, and sensors 70 may be included in any of the non-limiting examples described herein.

[0035] The properties of the ST system 18 operating in startup mode are generally described to further demonstrate their effect on and / or within the HP components 24. During startup operations of the power generation system 12, specifically when the HRSG 54 initially begins to generate steam, each component 20 ( FIG. 1 ), 22 ( FIG. 1 ), 24 may be at a reduced or pre-start temperature (e.g., at least approximately 38 degrees Celsius (°C) / 100 degrees Fahrenheit (°F)), but is immediately exposed to heated, high-temperature steam (generated in the exhaust fluid 60) if steam flow to each component 20, 22, 24 is permitted. In this case, any component 20, 22, 24 receiving the steam flow experiences a rapid temperature change and / or increased temperature, pressure, and / or surface stresses as a result of exposure to the heated, high-temperature steam. Subcomponents such as the check valve 114 can help reduce thermal fatigue and / or stress experienced by the HP components 24, the rotor 26, and / or portions of the ST system 18. The initial temperature of the incoming heating steam, for example, if not managed using embodiments of the present disclosure, can initially overstress the rotor 26 and / or other portions of the ST system 18. Therefore, methods according to the present disclosure can allow the inlet valve 104 to route steam to the LP and / or IP components 20, 22 first before allowing the steam to enter the HP component 24. Embodiments of the present disclosure can allow the control system 68 to predict the stresses imposed on the rotor 26 when the inlet valve 104 is opened to its minimum load position and control the amount of steam initially routed through the HP component 24 to warm and pressurize its interconnected components. At this point, the HP component 24 extracts substantially less energy from the passing steam compared to the amount of energy extracted at "minimum load" flow. When the predicted stress falls below a threshold, the inlet valve 104 is opened to its minimum load position. With steam flow to the HP component 24 in its minimum load position, the HP component 24 mechanically drives the rotor 26 to further extract energy from the steam.

[0036] Referring to FIG. 3 , a schematic diagram of a computing device 66 and its subcomponents is shown as part of system 10. In the illustration of FIG. 3 , only one ST system 18 is shown in detail, and the operative coupling between the computing device 66 and the various components of the ST system 18 from FIG. 1 is only shown schematically in FIG. 3 for clarity of illustration. As shown, the computing device 66 may include memory 202 on which a control system 68 operates. The control system 68 may be a software system integrated with or in operative communication with portions of the ST system 18 (e.g., valves 104, 110). The control system 68 may include, for example, a steam turbine (ST) control program 212. The turbine control program may cause the computing device 66 to affect and / or modify the ST system 18 and / or modify the existing operating methodology of the computing device 66 for operating the ST system 18. The computing device 66 shown in FIG. 3 represents one type of hardware for interacting with and / or controlling the ST system 18. As described herein, computing device 66 may react to various monitored attributes of ST system 18 to ensure safe and reliable operation of system 10 during startup operations. Within computing device 66, a turbine control program may monitor and / or interact with, and potentially override, other actions that computing device 66 takes to control ST system 18 during startup operations (e.g., adjusting valves 104, 110, modifying the amount of steam directed through supply conduit 58, etc.).

[0037] According to one example, the computing device 66 controls the ST system 18 during startup operations and can continuously evaluate whether to move the valves 104, 110 to various positions based on data measured via the sensors 70 and / or additional values ​​calculated via the control system 68. A turbine control program can cause the computing device 66 to predict stresses on the rotor 26 when the inlet valve 104 is moved to a minimum load position and route less steam through the HP components 24 to adjust the temperature and pressure therein and reduce the predicted stresses. Embodiments of the present disclosure may be configured or operated, in part, by a technician, the computing device 66, and / or a combination of a technician and the computing device 66. It is understood that some of the various components shown in FIG. 3 may be independently implemented, combined, and / or stored in memory for one or more separate computing devices included in the computing device 66. It is further understood that some of the components and / or functions may not be implemented, and additional schema and / or functionality may be included as part of the control system 68.

[0038] The computing device 66 may include a processor unit (PU) 228, an input / output (I / O) interface 230, a memory 202, and a bus 234. Additionally, the computing device 66 is shown in communication with an external I / O device 236 and a storage system 238. The control system 68 may provide a turbine control program, which may operate using various modules 242 (e.g., calculators, determiners, comparators, etc.) to perform various functions and / or logical steps. The various modules 242 may perform their respective functions using algorithm-based calculations, look-up tables, and similar tools stored in the memory 202 to process, analyze, and manipulate data. Generally, the PU 228 may execute computer program code and execute software such as the control system 68, which may be stored in the memory 202 and / or the storage system 238. While executing the computer program code, the PU 228 may read and write data from and to the memory 202, the storage system 238, and / or the I / O interface 236. Bus 234 may provide a communications link between each of the components within computing device 66. I / O devices 230 may comprise any device that allows a user to interact with computing device 66 or that allows computing device 66 to communicate with the equipment described herein and / or other computing devices. I / O devices 230 (including, but not limited to, keyboards, displays, pointing devices, etc.) may be coupled to computing device 66 directly or through intervening I / O controllers (not shown).

[0039] Memory 202 may also include various forms of data 250 related to various components of system 10, e.g., various forms of data and / or predetermined data that computing device 66 may use as reference to modify the operation of system 10. A turbine control program may store and interact with data 250 subdivided into various fields. For example, sensor data field 252 may store any and all types of data collected by sensors 70 (e.g., inlet temperature, outlet temperature, measured rotor stress, fluid flow, etc.) that may be used to monitor and control steam flow through HP component 24. Where applicable, sensor data field 252 may be divided into various subfields corresponding to specific types of data.

[0040] Data 250 may include one or more thresholds for various parameters, which may be organized into threshold data field 254. Threshold data field 254 may include, for example, one or more stress thresholds representing maximum allowable stresses on rotor 26. By calculating predicted stresses on rotor 26 that exceed the thresholds, computing device 66 may control the amount of steam flow through HP component 24, thereby reducing the predicted stresses on rotor 26. The stress prediction may be made before steam intake to HP component 24 is increased (e.g., via inlet valve 104) to provide a minimum load. The threshold stresses in threshold data field 254 may be calculated before the method of the present disclosure begins (e.g., in process P0.3 ( FIG. 5 ) described below) and may indicate the maximum allowable stresses on rotor 26 when valve 104 is opened to a minimum load position. In some cases, the thresholds in threshold data field 254 may be calculated based on past operation of ST system 18, system 10, other similar ST systems, and / or power generation systems, and / or may be analytical predictions. Although calculated or derived, thresholds for the predicted stresses may be stored in threshold data field 254 for reference by control system 68. Threshold data field 254 may further include boundaries for various safety parameters related to the operation of turbine components, such as HP component 24. For example, threshold data field 254 may include maximum current stresses on rotor 26 during a warm-up phase of turbine component operation, maximum temperatures in outlet 108 corresponding to respective temperatures in bowl 106, and / or other data indicative of safe turbine component operation.

[0041] The data 250 may include a valve position field 256 for storing various valve positions for each valve 104, 110 and / or other components of the system 10 (e.g., check valve 114) for regulating fluid flow, if applicable. The valve position field 256 may indicate a partially open position for the valve 104, 110 corresponding to a particular operating condition. For example, the valve position field 256 may include at least one partially open position for the inlet valve 104 that is less than a minimum load position for the inlet valve 104. Such a position for the inlet valve 104 may be referred to as a “warming position” because it is used to increase the temperature within the HP component 24 before more steam flow enters through the inlet valve 104. The valve position field 256 may also include multiple partially or fully open positions, including a minimum load position, and / or a position that allows for greater fluid flow than a minimum load position. During operation, the control system 68 may cause the inlet valve 104 to be adjusted between multiple warming positions that are less than a minimum load position until the predicted stress is less than the corresponding threshold value in the threshold data field 254.

[0042] In various embodiments, it may be desirable to overestimate the predicted stresses on the rotor 26. A technical advantage of overestimating the predicted stresses may include, for example, ensuring that opening the inlet valve 104 to a minimum load position does not significantly damage the rotor 26 or the HP components 24 during startup operations of the ST system 18. To intentionally overestimate the predicted stresses, the data 250 may include a bias constant field 258 for storing a corrective adjustment to the predicted stresses calculated via the predictive model 244. The bias constant field 258 may include an over-corrective adjustment to the calculated stresses, for example, in the form of a constant that is added to the predicted stresses. In a further example, the bias constant field 258 may take the form of a look-up table, algorithm, or the like for increasing the predicted stresses by varying an amount with reference to the operation of the ST system 18 and / or the HP components 24. In such an example, the table in bias constant field 258 may correlate, for example, a minimum load of 50 megawatts (50 MW), a rotor surface temperature of 300° C., an inlet fluid temperature of 350° C., and a predicted steam flow of approximately 40 kilograms per second (kg / s) with a bias constant of 5 megapascals (MPa). The correlated bias constant (e.g., 5 MPa in this example) may then be added to the initially calculated predicted stress to create a final value for the predicted stress. While organized, tabulated, etc., the bias constant values ​​in bias constant field 258 may be user-defined (e.g., via I / O device 236), calculated via predictive model 244, and / or generated using a combination of user inputs and / or functions implemented via control system 68 or applicable subcomponents.

[0043] Computing device 66 may comprise any general-purpose computing product (e.g., a personal computer, a server, a handheld device, etc.) for executing user-installed computer program code. However, it will be understood that computing device 66 is merely representative of various possible equivalent computing devices and / or technicians that may perform the various process steps of the present disclosure. Additionally, computing device 66 may be part of a larger system architecture operable to model and / or control various aspects and elements of ST system 18.

[0044] In this regard, in other embodiments, computing device 66 may comprise any special-purpose computing product containing hardware and / or computer program code for performing particular functions, any computing product containing a combination of special-purpose and general-purpose hardware / software, etc. In either case, the program code and hardware, respectively, may be created using standard programming and engineering techniques. In one embodiment, computing device 66 may include a program product stored on a computer-readable storage device that, when executed, may be operable to automatically control other elements of system 10. Computing device 66 may also take the form of a remote monitoring system that is, for example, part of a central monitoring system, which is responsible for monitoring several ST systems 18. In this case, computing device 66 may represent a part or subcomponent of the central control system.

[0045] 3 and 4 , an exemplary flow diagram for implementing method M1 according to various embodiments of the present disclosure is provided. Embodiments of the methodology described herein may be implemented using, for example, control system 68 of computing device 66, various modules and / or subcomponents of computing device 66 and / or control system 68. Method M1 according to the present disclosure may also depend on other components, such as sensors 70 communicatively coupled to computing device 66 and / or control system 68, to measure and / or otherwise determine various parameters used as the basis for the processes described herein. As described herein, control system 68 may adjust various operating parameters of power generation system 12, for example, by opening, closing, or otherwise adjusting the positions of valves 104, 110 to control predicted stresses on rotor 26. In further embodiments, control system 68 may be operable to modify other commands and / or actions taken via computing device 66 and / or control system 68, for example, by modifying bias constants to calculate predicted stresses on rotor 26. While the example flow diagram of FIG. 4 is shown with several processes organized into an example flow, it will be understood that one or more processes may be performed simultaneously and / or sequentially and / or in any alternative order while maintaining various technical features described by the examples herein.

[0046] 1 , 3 , and 4 together, an embodiment of the present disclosure provides a method M1 for controlling steam flow through turbine components during startup operation of a turbine system. Various methodologies provided herein are described with reference to an ST system 18 and an HP component 24 therein, by way of example. It is understood that embodiments of the present disclosure may be implemented for other types of turbomachinery and / or turbine components without substantial modification from one or more of the methodologies described herein. The methods described herein may be initiated by the control system 68 of the computing device 66 under certain conditions (e.g., detecting that the HP component 24 has begun operation) and / or may be implemented as part of a more general methodology for controlling the HP component 24, as described elsewhere herein. Processes implemented in further embodiments and / or as different control methods (i.e., decision D0.1 and process P2) are shown by way of example in FIG. 4 and described in more detail with respect to other figures.

[0047] As described herein, embodiments of the present disclosure control steam pressure within the HP component 24 of the ST system 18 during startup operations. The method includes a process P1 that adjusts the inlet valve 104 to a fully closed position (e.g., via a mechanical linkage, an electrical linkage, a converter, etc., generally indicated by the phantom line between the computing device 66 and the inlet valve 104). To prevent premature steam flow into the HP component 24 and associated stresses on the rotor 26, the control system 68 of the computing device 66 can implement a process P2 that adjusts the exhaust valve 110 to a fully open position (e.g., via a mechanical linkage, an electrical linkage, a converter, etc., generally indicated by the phantom line between the computing device 66 and the exhaust valve 110). After processes P1 and P2 are complete and the valves 104, 110 are in their respective positions, existing fluid can be extracted from the HP component 24, while incoming fluid must bypass the HP component 24 due to the closure of the inlet valve 104.

[0048] Following processes P1 and P2, the method may proceed to process P3, in which turbine control program module 242, or possibly predictive model 244, calculates predicted stresses on the rotor 26. Process P3 may be an initial process for sub-method M1.1 and may be performed in a loop manner until various technical conditions are met, as described herein. Sub-method M1.1 may generally include steps of evaluating whether the predicted stresses are below a threshold and, if applicable, adjusting the valves 104, 110 so that the predicted stresses are below the threshold. As described herein, the predicted stresses calculated in process P3 do not refer to current stresses on the rotor 26 or future stresses if the valves 104, 110 remain in their current positions. Rather, the predicted stresses calculated in process P2 refer to the instantaneous stresses (e.g., measured in MPa) on the rotor 26 due to the admitted steam when the inlet valve 104 is opened to its minimum load position (e.g., as defined in valve position field 256 of datum 250). If predictive model 244 intentionally overestimates the predicted stresses, process P2 may include adding a bias constant to the predicted stresses (e.g., as shown in bias constant field 258). However, when implemented, process P2 may include calculating the predicted stresses on rotor 26 using at least the surface temperature of rotor 26 and the steam temperature in inlet 102 (e.g., measured or calculated using sensors 70 and / or derived from data 250 such as the values ​​in sensor data field 252).

[0049] After calculating the predicted stresses for the rotor 26 in process P3, the method may proceed to decision D1, which determines (e.g., via module 242 of the turbine control program) whether the predicted stresses exceed corresponding thresholds for the ST system 18 and / or its current operating conditions. Such thresholds may be stored, for example, in threshold field 254 of data 250. In various embodiments, module 242 of the ST control program 212 may select one of several thresholds (e.g., based on user input, internal logic, look-up tables, and / or algorithms) to compare with the predicted stresses calculated in process P3. If the predicted stresses do not exceed the thresholds (i.e., "No" in decision D1), method M1 may terminate and / or proceed to further operations (e.g., process P2.1 shown as an example in FIG. 4). If the predicted stresses exceed the thresholds (i.e., "Yes" in decision D1), method M1 may proceed to subsequent operations to prepare the HP component 24 for the admission of steam.

[0050] In response to the predicted stress exceeding a threshold, submethod M1.1 may include adjusting the inlet valve 104 to a warming position less than the minimum load position for the HP component 24. For example, the warming position for the inlet valve may be configured to admit, for example, 10% of the available steam flow from the supply conduit 58, compared to the minimum load position that admits, for example, 25% of the available steam flow. In the warming position, the exhaust valve 110 remains fully open, and the check valve 114 may allow excess steam to be directed away from the condenser 62, if desired and / or applicable. With the inlet valve 104 in the warming position, the incoming steam may impart some torque to the rotor 26 without extracting significant energy, while also increasing the pressure in the exhaust passage 112.

[0051] After opening the inlet valve 104 to the warming position in process P4, process P5 of submethod M1.1 may include allowing the incoming steam flow through the HP component 24 to pressurize the discharge passage 112. The incoming steam may, among other things, apply pressure to the physical components of the discharge passage 112 (including, for example, the dump tube to the condenser 62), thereby increasing the total pressure. The incoming steam flow also gradually increases the surface temperature of the rotor 26, making it less susceptible to stresses from the incoming steam.

[0052] As the incoming steam flow is permitted to pressurize the exhaust passage 112, method M1.1 may include decision D2, which compares the pressure in the exhaust passage 112 to a target value. The target value may indicate that the pressure in the exhaust passage 112 is sufficient to permit pressurization of the HP component 24. The target value for the pressure in the exhaust passage 112 may be stored, for example, in threshold field 254 or elsewhere in data 250. The measured pressure in the exhaust passage 112 may be obtained directly via sensor 70 and / or calculated from other data 250 via module 242. Start-up operations of the ST system 18 may require increasing the pressure in the HP component 24 to further reduce stress on the rotor 26. After the exhaust passage 112 is initially pressurized, pressurization of the HP component 24 can proceed more effectively. If the pressure in the exhaust passage 112 has not reached its target (i.e., “No” at decision D2), the method may return to process P5 to further pressurize the exhaust passage 112. Decision D2 may be repeated after a predetermined time delay or may be performed continuously. If the pressure in the exhaust passage 112 has reached its target (i.e., "Yes" at decision D2), the method may proceed to process P6, which partially closes the exhaust valve 110 while maintaining the inlet valve 104 in the warming position. Process P6 keeps the total steam flow through the HP component 24 substantially the same, but increases the upstream pressure (i.e., the pressure within the HP section 24).

[0053] Further analysis may include process P7, which monitors one or more safety parameters of the turbine (e.g., HP component 24) compared to corresponding boundaries. As used herein, the term “safety parameter” refers to a quantity indicative of the current operating state of a turbine component and / or the likelihood that the HP component 24 will be adversely affected. Examples of safety parameters, as described herein, may include current or “actual” stresses (as distinguished from predicted stresses) on the rotor 26, a predicted temperature at the outlet 108 based on the actual temperature in the bowl 106, and / or similar properties. The predicted temperature at the outlet 108 may be particularly relevant because, for example, if the steam flow through the HP component 24 is too low, the rotating blades may impart energy to the steam, which may in turn raise the temperature at the turbine outlet to an unacceptable level. In decision D3, module 242 of turbine control program 212 may compare one or more of the safety parameters monitored in process P7 to their respective boundaries. The boundaries for each safety parameter may be stored in threshold field 254 of data 250 or elsewhere in memory 202. According to one example, decision D3 may include comparing the current stress on rotor 26 (e.g., monitored by sensor 70) to a maximum allowable stress. In another example, decision D3 may include comparing a predicted temperature in outlet 108 to its desired maximum value based on the current temperature in bowl 106. If the safety threshold violates its boundary (i.e., "Yes" at decision D3), the method may include process P8, which partially opens exhaust valve 110 to bring the monitored safety parameter back into the desired range. If the safety parameter does not violate the boundary (i.e., "No" at decision D3), the method may proceed to further steps. In some cases, the monitoring of the safety parameter in process P7 and decision D3 may be performed in a loop, as shown by the phantom lines in FIG. 4.

[0054] The present disclosure may further include decision D4 whether a monitoring period has occurred (e.g., a desired time period, user confirmation, and / or a desired number of processing loops). If the monitoring period has elapsed (i.e., "Yes" at decision D4), the method may return to process P3 to recalculate the predicted stress on the rotor. If further monitoring is required (i.e., "No" at decision D4), the method may return to process P5 for further pressurization of the turbine components (e.g., HP component 24). If the predicted stress now falls below the threshold (i.e., "Yes" at process D1), sub-method M1.1 may end. If the predicted stress remains above the threshold (i.e., "No" at process D2), processes P5, P6, and decision D2 may be repeated with the inlet valve 104 in the warming position but with a higher target pressure applied to the exhaust passage 112 and / or HP component 24.

[0055] 1 and 3-5, additional operations may be implemented in conjunction with method M1 to provide further control of ST system 18. Method M1 is illustrated via a single box in the flow diagram of FIG. 5, with it being understood that method M1 may include various processes and decisions described herein with respect to FIG. 4. While some processes are illustrated by example as occurring before or after the implementation of method M1, it will be understood that some operations may be rearranged and / or omitted in various further embodiments.

[0056] Process P0.1 in various embodiments may include, for example, initiating operation of the ST system 18 by initiating steam flow through the LP and IP components 20, 22 while preventing steam flow through the HP component 24 (e.g., by fully closing the inlet valve 104). Such a configuration may be limited, for example, to a configuration of the ST system 18 having a "cascade bypass" to control steam flow through the components 20, 22, 24. Once process P0.1 is completed, the HP component 24 remains dormant and therefore does not drive movement of the rotor 26.

[0057] Process P0.2 of the present disclosure may include generating a predictive model 244 for the ST system 18. The predictive model 244 may be generated based on various information in data 250, such as, for example, recorded data in sensor data field 252, operational settings of the ST system 18, and / or other inputs. The predictive model 244 may take the form of a generalized formula, algorithm, look-up table, etc. for predicting stresses on the rotor 26 based on the operating conditions of the ST system 18. According to a particular example, the predictive model 244 may be configured to generate predicted stresses on the rotor 26 using the surface temperature of the rotor 26, the steam temperature in the inlet 102 to the HP component 24, one or more bias constants, such as those recorded in bias constant field 258 of the data 250, and / or any other data related to the operation of the system 10. The generation of the predictive model 244 in process P0.2 may be a single operation performed before, after, or simultaneously with other processes described herein. In a further example, the generation of the predictive model 244 may be continuous and may incorporate additional readings from the sensor 70 to calculate the predicted stress on the rotor 26 when the inlet valve 104 is adjusted to the minimum load position.

[0058] After or during generation of predictive model 244 in process P0.2, the method may include process P0.3, which calculates a threshold value for rotor stress to be used in decision D1 ( FIG. 4 ) of method M1. The calculated threshold value may be stored, for example, in threshold value field 254 for future reference and / or may be continuously updated as ST system 18 continues to operate. In either case, process P0.3 may include predictive model 244 of control system 68 using current operating conditions of system 10 (e.g., surface temperature of rotor 26, steam temperature in inlet 102 to HP component 24, one or more bias constants such as those recorded in bias constant field 258 of data 250, and / or any other data related to the operation of system 10) to generate the threshold value to be compared to the predicted stress in decision D1.

[0059] An embodiment of the present disclosure can continue by operating the ST system 18 with the HP component 24 inactive, i.e., with no steam entering the HP component 24 because the inlet valve 104 remains closed. In this case, the LP and IP components 20, 22 continue to operate and mechanically drive the rotation of the rotor 26. As the ST system 18 continues to operate with the HP component 24 inactive, module 242 of the control system 68 can determine whether the steam flow to the LP and IP components 20, 22 has reached a target level. The target steam flow to the LP and IP components 20, 22 may be manually selected via a user of the control system 68 and / or stored in the data 250 (e.g., as part of the sensor data field 252 and / or alternatively, as part of the threshold field 254). Decision D0.1 in an embodiment of the present disclosure can evaluate whether the steam flow through the LP and IP components 20, 22 has reached its target. If the steam flow through the LP and IP components 20, 22 is below the target (i.e., "No" in decision D0.1), the ST system 18 may continue to operate without steam flow entering the HP components 24 (i.e., the inlet valve 104 remains in a closed position). If the steam flow through the LP and IP components 20, 22 is equal to or greater than the target (i.e., "Yes" in decision D0.1), various processes of method M1, described elsewhere herein, may be initiated. As shown in FIG. 4 , process P1, which adjusts the exhaust valve 110 to a fully open position, may follow decision D0.1 in the exemplary embodiment. Thus, method M1 may be fully implemented using sub-method M1.1, if applicable, to determine whether the predicted stress on the rotor 26 is below an applicable threshold. If the predicted stress on the rotor 26 is determined to be below the threshold (i.e., method M1 ends), further actions may be performed.

[0060] After method M1 is completed and the predicted stress falls below a threshold, further operations may include process P2.1 of opening inlet valve 104 to a minimum load position. The minimum load position may be defined in valve position field 256 of data 250. Through one or more operable couplings (e.g., electrical connections, mechanical converters, etc.) between computing device 66 and inlet valve 104, inlet valve 104 may be adjusted to at least the minimum load position, thereby allowing steam to enter HP component 24 and mechanically drive rotation of rotor 26. While adjusting inlet valve 104 imparts stress on rotor 26, the imparted stress is significantly less than in conventional operation in which method M1 is omitted.

[0061] Continuing with process P2.2, the ST system 18 may continue to allow steam to flow through the inlet valve 104 into the HP component 24. Once the inlet valve 104 is in its minimum load position, the control system 68 may adjust the exhaust valve 110 to a closed position. Adjustment of the exhaust valve 110 may be performed, for example, via a mechanical connection between the computing device 66 and the exhaust valve 110, a mechanical converter, or the like. With the exhaust valve 110 in the closed position, fluid in the outlet 108 may continue to flow through the check valve 114 to the reheater component, as described elsewhere herein. At this stage, the HP component 24 has stopped operating in a “start” mode and has begun to generate at least a minimum load through the rotor 26. Optionally, the method may end (“complete”) after adjusting the exhaust valve 110 to a fully closed position, as shown by the phantom line in FIG. 5 . In a further example, the method may return to process P0.3 at any point where the system 10 resumes startup operation, for example, by ceasing operation for a set period of time and / or transitioning to a different type of operating mode.

[0062] In various embodiments, control system 68 can use operating characteristics of system 10 to modify the calculation of thresholds in process P0.3 in further embodiments. For example, if predictive model 244 intentionally overestimates predicted stresses via a bias constant, process P2.3 may calculate the difference between the actual stresses on rotor 26 and the predicted stresses. The calculated difference can be expressed, for example, in terms of a percentage, a MPa difference, etc. In some cases, the bias constant can be further adjusted based, for example, on the start-up temperatures of HP components 24 (e.g., as measured by sensor 70), the pressure profile of ST system 18 (e.g., the pressure within each component 20, 22, 24) with inlet valve 104 in the warmed position, and / or other operating characteristics. Predictive model 244 can then use the difference to adjust the bias constant for the predicted stresses by, for example, recalculating or adjusting various attributes of algorithms, lookup tables, etc. The adjusted bias constant can be stored as data 250, for example, in bias constant field 258. The method can then end ("Complete") or return to process P0.3, which uses the adjusted bias constant to calculate a threshold value for the predicted stress.

[0063] A technical effect of the embodiments described herein includes predicting the stresses that steam flow entering a high-pressure component of a steam turbine will place on a rotor to drive an electrical generator. When the predicted stresses exceed a desired level, a technical effect of the present disclosure ensures that the high-pressure component is preheated and prepressurized before more steam enters the high-pressure component to drive the rotor. A further technical effect of the embodiments described herein includes using the actual stresses on the rotor in a particular operation as training data for predicting how future steam flows will stress the same rotor, or similar rotors in other steam turbine systems, in future operations.

[0064] As used herein throughout this specification and claims, approximation language can be applied to modify any quantitative expression that can reasonably vary without resulting in a change in the basic function involved. Thus, values ​​modified by terms such as "approximately," "about," and "substantially" are not limited to the exact value specified. In at least some instances, approximation language can correspond to the precision of the instrument used to measure the value. Herein and throughout this specification and claims, range limitations are combinable and / or interchangeable, and unless the context or language dictates otherwise, such ranges are identified and include all subranges encompassed therein. "About," as applied to a particular value in a range, applies to both endpoints and can indicate + / - 10% of the stated value, unless specifically dependent on the precision of the instrument used to measure the value.

[0065] The corresponding structure, material, acts, and equivalents of all means-plus-function or step-plus-function elements in the following claims are intended to encompass any structure, material, or acts for performing that function in combination with other specifically claimed claim elements. The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The present embodiments were chosen and described in order to best explain the principles and practical application of the disclosure and to enable others skilled in the art to understand the disclosure in various embodiments with various modifications as suited to the particular uses envisioned. [Explanation of symbols]

[0066] 10 Systems 12 Combined cycle power generation system 18 Steam Turbine (ST) System 20 Low Pressure (LP) Components 22 Intermediate Pressure (IP) Components 24 HP components, HP section 26 rotor 28 Generator 30 Gas Turbine (GT) System 32 Compressor 34 Fluid 38 Compressed Fluids 40 Combustor 42 Fuel 44 Fuel supply source 46 Combustion Gas 48 Turbine Components 50 shaft 52 Generator 54 Heat Recovery Steam Generator (HRSG) 58 Supply conduit 59 Exhaust channel 60 Exhaust Fluid 61 stacks 62 Condenser 64 Steam exhaust duct 66 Computing Devices 68 Control System 70 sensors 102 Entrance 104 Inlet valve 106 Bowl 108 Exit 110 Outlet valve, exhaust valve 112 Discharge passage 114 Check valve 202 memory 212 Steam Turbine (ST) Control Program 228 Processor Unit (PU) 230 Input / Output (I / O) Interface, I / O Device 234 Bus 236 External I / O devices, I / O interfaces 238 Memory System 242 modules 244 Predictive Model 250 data 252 Sensor Data Field 254 Threshold Data Field 256 Valve Position Field 258 Bias Constant Field P1 Process P2 Process P3 Process P4 Process P5 Process P6 Process P7 Process P8 Process P0.1 Process P0.2 Process P0.3 Process P0.4 Process P2.1 Process P2.2 Process P2.3 Process D1 Judgment D2 judgment D3 Verdict D4 judgment D0.1 Judgment M1 method M1.1 Sub-method

Claims

1. 1. A method (M1, M1.1) for controlling steam pressure in a turbine component (48) during startup operations, the turbine component (48) being fluidly coupled between an inlet (102) having an inlet valve (104) for controlling steam flow into the turbine component (48) and an exhaust outlet (110) having an exhaust valve (110) for controlling steam flow to an exhaust passage (112), the method (M1, M1.1) comprising: adjusting the exhaust valve (110) to a fully open position and the inlet valve (104) to a fully closed position (P1, P2); calculating (P3) predicted stresses on the rotor (26) of the turbine component (48) based on predicted steam flow with the inlet valve (104) in a minimum load position, rotor (26) surface temperature, and inlet (102) steam temperature; determining whether the predicted stress exceeds a threshold (D1); adjusting (P4) the inlet valve (104) to a warming position less open than the minimum load position such that steam flow through the turbine component (48) pressurizes the exhaust passage (112) in response to the predicted stress exceeding the threshold; partially closing (P6) the exhaust valve (110) while maintaining the warming position of the inlet valve (104) in response to steam in the exhaust passage (112) reaching a target pressure; determining (D3) whether a safety parameter of the turbine component (48) violates a boundary while maintaining the warming position of the inlet valve (104); and partially opening (P8) the exhaust valve (110) while maintaining the warming position of the inlet valve (104) in response to the safety parameter of the turbine component (48) violating the boundary; recalculating (P3) the predicted stresses on the rotor (26) with the inlet valve (104) in the warming position; and (P2.1) opening the inlet valve (104) to at least the minimum load position in response to the predicted stress not exceeding the threshold. Including, The method (M1, M1.1), wherein the safety parameter comprises a predicted steam temperature drop across the turbine component (48) based on an upstream steam temperature, and the boundary comprises a minimum steam temperature for an outlet (108) from the turbine component (48).

2. 2. The method of claim 1, wherein the safety parameter for the turbine component comprises an actual stress on a rotor with the inlet valve in the warmed position, and the boundary comprises a stress limit for the rotor.

3. The turbine component (48) comprises a high pressure (HP) component (24) of a steam turbine (ST) system (18), and the method (M1, M1.1) comprises: Initiating (P0.1) steam flow through intermediate pressure (IP) and low pressure (LP) components (22 and 20) of the ST system (18) prior to calculating the predicted stresses on the rotor (26); determining (D0.1) whether the steam flow through the IP component (22) and the LP component (20) of the ST system (18) reaches a target level; calculating (P3) the predicted stresses on the rotor (26) in response to the steam flow through the IP component (22) and the LP component (20) reaching the target level; 2. The method of claim 1, further comprising:

4. 2. The method (M1, M1.1) of claim 1, further comprising adjusting (P2.2) the exhaust valve (110) to a fully closed position after opening the inlet valve (104) to at least the minimum load position.

5. 2. The method of claim 1, further comprising, before adjusting the exhaust valve to the fully open position and adjusting the inlet valve to the fully closed position, generating a predictive model for the turbine component to calculate the predicted stresses based on at least the rotor surface temperature, the inlet steam temperature, and a bias constant.

6. 6. The method of claim 5, further comprising adjusting (P2.3) the bias constant of the predictive model based on a start-up temperature of the turbine component and a pressure profile of the turbine component with the inlet valve in the warming position after reducing the steam flow through the exhaust valve.

7. 1. A program product stored on a computer-readable storage medium for controlling steam pressure within a turbine component (48) during startup operations, the turbine component (48) being fluidly coupled between an inlet (102) having an inlet valve (104) for controlling steam flow to the turbine component (48) and an exhaust outlet (110) having an exhaust valve (110) for controlling steam flow to an exhaust passage (112), the computer-readable storage medium being configured to provide a computer system with: adjusting the exhaust valve (110) to a fully open position and the inlet valve (104) to a fully closed position (P1, P2); calculating (P3) predicted stresses on the rotor (26) of the turbine component (48) based on predicted steam flow with the inlet valve (104) in a minimum load position, rotor (26) surface temperature, and inlet (102) steam temperature; determining whether the predicted stress exceeds a threshold (D1); adjusting (P4) the inlet valve (104) to a warming position less open than the minimum load position such that steam flow through the turbine component (48) pressurizes the exhaust passage (112) in response to the predicted stress exceeding the threshold; partially closing (P6) the exhaust valve (110) while maintaining the warming position of the inlet valve (104) in response to steam in the exhaust passage (112) reaching a target pressure; determining (D3) whether a safety parameter of the turbine component (48) violates a boundary while maintaining the warming position of the inlet valve (104); and partially opening (P8) the exhaust valve (110) while maintaining the warming position of the inlet valve (104) in response to the safety parameter of the turbine component (48) violating the boundary; recalculating (P3) the predicted stresses on the rotor (26) with the inlet valve (104) in the warming position; and (P2.1) opening the inlet valve (104) to at least the minimum load position in response to the predicted stress not exceeding the threshold. and program code for causing the execution of an action including: the safety parameter comprises a predicted steam temperature drop across the turbine component (48) based on an upstream steam temperature, and the boundary comprises a minimum steam temperature for an outlet (108) from the turbine component (48).

8. 8. The program product of claim 7, wherein the safety parameters for the turbine component include actual stresses on a rotor with the inlet valve in the warmed position, and the boundaries include stress limits for the rotor.

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