DE102010061449A1 - Method for starting up a steam turbine - Google Patents

Abstract

The present invention has the technical effect of reducing the start-up time associated with starting a steam turbine (100). Embodiments of the present invention provide a novel method of reducing a steam / metal temperature mismatch that exists during startup of a steam turbine (100). In essence, embodiments of the invention can increase the pressure of the steam upstream of an inlet valve (115) associated with a high pressure (HP) section (120) of a steam turbine (100). The initially high pressure of the steam can reduce the enthalpy of the steam and thereby lower the temperature of the steam supplied to the HP section (120)

Description

Background of the invention

The present invention relates generally to the operation of a turbomachine, and more particularly to a method for reducing the startup time of a steam turbine.

The start-up and loading process of some known steam turbines typically includes several phases occurring at different load ranges. One reason for this start-up and loading process of the steam turbine is the rotor load control. A rotor of the steam turbine may undergo an overload case during the startup and initial load phases. An overload can worsen the material properties of the rotor. An engine load control may rate the load on the steam turbine with the aim of keeping the rotor load within an allowable range.

Known methods for reducing the likelihood of overloading are to control the temperature of the steam coming from a boiler, such as a boiler. B., but not limited to, the heat recovery steam generator (HRSG) exits to keep at a relatively low temperature. For example, in a combined cycle power plant, but not limited to, the gas turbine is maintained at a low load idle reserve or the like to ensure that the temperature of the steam generated in the HRSG is beneficial to the steam turbine. For a cold start, this temperature may be about 371 ° C (700 ° F). As a cold start, the startup of the steam turbine can be considered after a break period.

For combination cycle applications, the vapor pressure is typically related to the gas turbine load. During a cold start, the gas turbine may be limited to operating at a load that is approximately 40 percent of the rated pressure prior to starting the steam turbine. Due to the relatively low initial input pressure, when the steam is supplied to the steam turbine, the enthalpy of the input steam is also relatively high. In addition, when the steam is supplied to the steam turbine, the pressure ratio between the input and output valves is relatively high. These operating factors may result in a steam temperature in a portion of the steam turbine, on the turbine housing, that is about 22,2 to 27,8 ° C (40 to 50 ° F) lower than the inlet temperature of the steam. During a cold start of the steam turbine, this reduction in steam temperature may not be sufficient to prevent an overload case on the turbine rotor.

Therefore, there is a desire for an improved starting method of a steam turbine. The procedure should reduce the startup time. This method should also eliminate or reduce the overload level experienced by the rotor.

Brief description of the invention

In one embodiment of the present invention, a method ( 300 . 400 ) for starting a power plant machine, the method ( 300 . 400 ) comprises the steps of: providing a steam turbine ( 100 ) configured to convert steam to mechanical torque; the steam turbine ( 100 ) an HP section ( 120 ) having; and increasing a vapor pressure upstream of an inlet valve ( 115 ) to a suitable print area ( 315 ), whereby the inlet valve ( 115 ) upstream of the HP section ( 120 ) is located; wherein the step of increasing the vapor pressure ( 115 ) the temperature of the steam before entering the HP section ( 120 ) decreased.

In an alternative embodiment of the present invention, a method ( 300 . 400 ) for starting a power plant with a steam turbine ( 100 ), the method ( 300 . 400 ) comprises the steps of: providing a steam turbine ( 100 ) configured to convert steam to mechanical torque; the steam turbine ( 100 ) an HP section ( 120 ) and a bypass system ( 110 ) having; Determine if a cold start of the steam turbine is required ( 410 ); Increasing a pressure of the steam upstream of an inlet valve ( 115 ) on a suitable printing area ( 415 ), whereby the inlet valve ( 115 ) upstream of the HP section ( 120 ) is located; Determine if the steam is upstream of the inlet valve ( 115 ) in the appropriate pressure range ( 420 ) is located; Starting a startup process of the steam turbine ( 430 ), if a start-up condition is met ( 425 ); and controlling the intake valve ( 115 ) so that there is steam in the HP section ( 120 ) 440 . 445 ) can flow; wherein the step of increasing the vapor pressure reduces a temperature of the vapor before the vapor enters the HP section ( 120 ) flows.

Brief description of the drawings

1 FIG. 10 is a schematic diagram illustrating an HP section of a steam turbine that represents an environment in which an embodiment of the present invention may operate. FIG.

2 FIG. 13 is a graph illustrating operating curves according to a known steam turbine starting method. FIG.

3 FIG. 10 is a block diagram illustrating a method used to start up a turbomachine according to one embodiment of the present invention.

4 FIG. 10 is a block diagram illustrating a method used to start up a turbomachine according to an alternative embodiment of the present invention. FIG.

5 FIG. 13 is a graph illustrating operational curves of a startup process of a steam turbine according to an embodiment of the present invention.

Detailed description of the invention

The present invention has the technical effect of reducing the start-up time associated with starting a steam turbine. Embodiments of the present invention provide a new method for reducing a vapor / metal temperature mismatch that occurs during start-up of a steam turbine. In essence, embodiments of the invention may increase vapor pressure upstream of an inlet valve associated with a high pressure (HP) section of a steam turbine. The initially high pressure of the steam can reduce the enthalpy of the steam and thereby reduce the temperature of the steam supplied to the HP section.

Detailed example embodiments are disclosed herein. However, the specific structural and functional details disclosed herein are merely representative of the purposes of describing example embodiments. However, example embodiments may be embodied in many alternative forms and should not be construed as limited only to the embodiments set forth herein.

Accordingly, as example embodiments are capable of various modifications and alternative forms, their embodiments are illustrated by way of example in the drawings and described in detail herein. It should be understood, however, that there is no intention to limit example embodiments to the specific forms disclosed, but on the contrary, example embodiments are intended to cover all modifications, equivalents, and alternatives falling within the scope of the example embodiments.

It should also be understood that although the terms "first ...", "second ..." etc. are used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element could be termed a second element and also a second element could be termed a first element without departing from the scope of the example embodiments. As used herein, the term "and / or" includes any combination of one or more of the associated specified elements.

The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the example embodiments. As used herein, the singular forms "one, one, one," and "the, that," are also meant to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "having" "having," "containing," and / or "containing," as used herein, includes the presence of identified features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

It should also be noted that in some alternative implementations, the specified functions / actions may be in a different order than the order given in the figures. For example, two consecutive figures may be executed concurrently, essentially depending on the functionality / operation involved, or may sometimes be executed in reverse order.

In the figures, in which the various reference numerals designate like parts throughout the several views, is 1 a schematic representation of an HP section 120 a steam turbine 100 which represents an environment in which an embodiment of the present invention can operate. Typically, a steam turbine 100 several sections, such as. For example, but not limited to, a high pressure (HP), an intermediate pressure (IP) and a low pressure (LP) section on. Embodiments of the present invention may control the vapor flow in the HP section 120 Taxes. Therefore, the focus 1 and the discussion below for the HP section 120 , which with a capacitor 140 is summarized. For convenience, the IP drum and the IP section, the LP drum and the LP section, and the heat recovery components are in FIG 1 not shown. However, embodiments of the present invention may be applied to a steam turbine 100 which has some or all of these sections and components or the like.

A control system 190 can by using known methods for starting the steam turbine 100 Follow the steps below. Steam from an IP drum can be fed to the IP section of the steam turbine. Subsequently, the steam turbine 100 to full speed without load (FSNL - Full-Speed-No-Load). Subsequently, the steam turbine 100 synchronize with a network system or the like. Subsequently, the transition of steam from the IP section in full power to the HP section 120 respectively. This is where an inlet valve begins 115 open to steam from the HP drum 105 to the HP section 120 to flow. At the same time, the control system monitors 190 the rotor load. If the rotor loads exceed a permissible range, then the control system 190 the steam flow in the HP section 120 Stop or reduce for a predetermined waiting time. After the rotor loads have reduced to a permissible range, the control system can 190 continue steam in the HP section 120 by means of the inlet valve 115 Initiate until the full steam flow is reached or the steam turbine reaches a load setpoint.

2 is a record 200 , the operating curves according to a known starting method of a steam turbine 100 as described in 1 illustrated. A first vertical axis represents temperature (in ° F) and pressure (in psia). A second vertical axis represents the load (in percent). The first and second vertical axes are plotted over the startup time (in minutes) on the horizontal axis. The data series 205 represents the actual HP rotor load and the data series 210 represents the permissible load limit. The data series 215 and 220 represent the HP inlet pressure or temperature. The entrance area is the entry point 130 in 1 shown. The data series 225 may be the HP case temperature shown on the HP case 125 in 1 represent.

The inlet area 130 may be considered an area upstream and adjacent to the inlet valve 115 to be viewed as. The outlet area 135 may be considered an area downstream and adjacent to the inlet valve 115 to be viewed as.

2 represents the HP rotor loading from approximately 8 minutes to approximately 24 minutes 205 the permissible load limit 210 exceeded. To correct this situation, the control system can 190 the inlet valve 115 in a closed position for a predetermined waiting time. As shown in 2 take the rotor loads to a permissible range at approximately 25 minutes. Here can the control system 190 the inlet valve 115 Steer to an open position to continue steam in the HP section 120 to flow as described. The duration in which the HP rotor load 205 the permissible load 210 passed, approximately 16 minutes, prevented the steam turbine 100 at the conclusion of the start-up process.

As can be appreciated, the present invention may be embodied as a method, system, or computer program product. Accordingly, the present invention may include the farm of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all substantially referred to herein as a "circuit," "module "Or" system ". Further, the present invention may take the form of a computer program product on one of a computer usable storage medium having computer usable program code embodied in a medium. As used herein, the terms "software" and "firmware" are interchangeable and include any in a memory such as memory. A program stored in a RAM, ROM, EPROM, EEPROM, and nonvolatile RAM (NVRAM) memory for execution by a processor. The above memory types are exemplary only and thus not limiting on the type of memory usable for storing a computer program.

Any suitable computer-readable medium can be used. The computer-usable or computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, device, or transmission medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include an electrical connection to one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable media Read-only memory (EPROM or flash memory), an optical fiber, a compact disc portable read only disc (CD-ROM), an optical storage device, a transmission medium such as a CD-ROM; For example, those that support the Internet or an intranet, or a magnetic storage device. Note that the computer usable or computer readable medium may even be paper or other suitable medium on which the program is printed, since the program electronically, for example, by optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. In the context of this document, a computer usable or computer readable medium may be any medium that may contain, store, transfer, distribute, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

As used herein, the term "processor" refers to central processing units, microprocessors, microcontrollers, reduced instruction set (RISC) circuits, application specific integrated circuits (ASICs), logic circuits, and any other circuit or processor disclosed in US Pat are able to perform the functions described herein.

The computer program code for carrying out operations of the present invention may be stored in an object-oriented programming language, such as a computer program. B. Java7, Smalltalk or C ++ or the like. However, the computer program code for performing operations of the present invention may also be used in conventional procedural programming languages, such as computer programs. B. the programming language "C" or a similar language written. The program code may be executed entirely on the user's computer, partially on the user's computer as a standalone software package, partly on the user's computer and partly on a remotely located computer or completely on the remote user. In the latter scenario, the remote computer may be connected to the user computer via a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer via, for example, the Internet using an internet service provider.

The present invention will now be described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It should be understood that each block from the flowchart illustrations and / or block representations, and combinations of blocks in the flowchart illustrations and / or block representations may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a standard computer, special purpose computer or other programmable data processing device to create a machine such that the instructions executed via the computer's processor or other programmable data processing device include means for implementation of the functions / actions specified in the flowchart and / or presentation block or blocks.

These computer program instructions may also be stored in computer-readable storage that may instruct a computer or other programmable computing device to function in a specific manner so that the instructions stored in the computer-readable memory produce an article of manufacture with instructional means such as those shown in the flowchart and / or. or block block or blocks specified functions / implement actions. The computer program instructions may also be loaded on a computer or other programmable data processing device to effect execution of a series of operations on the computer or other programmable device to generate a computer-implemented process such as that on the computer or other instructions provide steps for the implementation of the functions / actions specified in the flowchart and / or block diagram or blocks.

Embodiments of the present invention provide a new start-up procedure. As described below, embodiments of this method may provide the pressure of the vapor at the inlet prior to the HP section 120 increase. This can change the temperature of the steam before entering into the HP section 120 reduce what the rotor loads can reduce. Then, during the initial load of the steam turbine, the process may reduce the intake vapor pressure. This can change the temperature of the HP section 120 flowing steam to a normal operating range in the HP housing 125 increase.

In the figures is 3 a block diagram showing a procedure 300 represents that for starting a steam turbine 100 according to one embodiment of the present invention is used. The procedure 300 can through the control system 190 as shown in 1 be executed. The control system 190 may provide a graphical user interface (GUI) or the like that allows an operator to do with the method 300 to interact.

In step 305 can the procedure 300 determine the initial metal temperatures of the steam turbine. Here can the control system 190 Data concerning the metal temperatures of temperature measuring devices obtained in the rotor of the steam turbine 100 are installed.

In step 310 can the procedure 300 Determine if a cold start of the steam turbine 100 is required. A cold start can be considered a startup of a steam turbine 100 considered to be idle for a predetermined duration. Components of the steam turbine 100 typically require longer warm-up periods when operating under cold start conditions. The control system 190 may include an operating timer or the like, which determines when a cold start is required. If a cold start is required, the procedure may 300 to the step 315 pass; otherwise, the method may go to step 325 pass.

In step 315 can the procedure 300 the pressure of the HP vapor at the inlet 130 increase to a suitable pressure range. Referring again to 1 Embodiments of the present invention may include the bypass valve 110 in a position that allows the appropriate pressure range. In one embodiment of the present invention, the pressure range may range from approximately 1200 psia to approximately 1500 psia.

In step 320 can the procedure 300 then determine if the pressure of the steam at the inlet 130 lies in the appropriate pressure range. If the pressure of the steam is in the appropriate pressure range, then the process can 300 to the step 325 pass; otherwise, the procedure may 300 to the step 315 to return.

In step 325 can the procedure 300 Determine if a start-up condition is met. Here can the control system 190 Includes start-up requirements that serve to ensure that various systems of the steam turbine 100 are ready, and / or allow the starting process. If the startup requirement is met, then the procedure can 300 to the step 330 pass; otherwise the process can 300 to the step 325 return until the start-up condition is met.

In step 330 can the procedure 300 with the starting process of the steam turbine 100 kick off. Here, steam from the IP drum can enter the IP section of the steam turbine 100 be supplied. Subsequently, the steam turbine 100 Accelerate to full speed without load (FSNL).

In step 335 can the procedure 300 the steam turbine 100 synchronize. Here is the steam turbine 100 electrically connected to a network system or the like.

In step 340 can the procedure 300 with the control of the intake valve 115 kick off. This can take the steam out of the HP drum 105 allow that to the HP section 120 to fill up and warm up adjacent piping.

In step 345 can the procedure 300 on the full steam flow from the IP section to the HP section 120 pass. Here is the inlet valve 115 continue to open, causing an entry of steam into the HP section 120 allows.

In step 350 can the procedure 300 determine if the rotor loading level is acceptable. Here can the control system 190 Monitor the rotor load in real time and compare the actual rotor load with the allowable load limit. If the rotor loads are not within the allowable range, then the method may be used 300 to the step 355 pass; otherwise, then the procedure can 300 to the step 360 pass.

In step 355 can the procedure 300 the steam flow in the HP section 120 maintained or reduced for a predetermined waiting period. After the rotor loads have reduced to the allowable range, then the control system 190 Continue with the inlet of steam in the HP section 120 via the inlet valve 115 Continue.

In step 360 can the procedure 300 the temperature of the steam at the inlet 130 Increase approximately to a nominal temperature. Here can the control system 190 the bypass valve 110 control to a position that allows a reduction of the vapor pressure, which allows an increase in the steam temperature as described.

In step 365 can the procedure 300 the temperature of the steam in the HP case 125 increase. Here can the control system 190 the bypass valve 110 control to a position that allows a reduction of the vapor pressure, which allows an increase in the steam temperature as described.

In step 370 can the procedure 300 increase the load to a base load or another load reference. Here can the control system 190 with the taking in of steam in the HP section 120 via the inlet valve 115 continue until the desired load is reached.

In step 375 can the procedure 300 comply with the load setpoint. Here is the procedure 300 the inlet valve 115 as needed to control the load.

4 is a block diagram showing a procedure 400 which is used for starting up a turbomachine according to an alternative embodiment of the present invention 3 The steps described can be repeated. Therefore, the discussion of 4 on the differences between the procedures 300 and 400 , The steps 360 and 365 of the procedure 300 be in the process 400 reversed. Here the procedure prioritizes 400 the step of increasing the temperature of the steam in the HP housing 125 in step 460 against the step of increasing the temperature of the vapor at the inlet 130 , This approach in the process 400 is opposite to that in the process 300 The approach used is reversed and can be used to further reduce the rotor loading level.

Embodiments of the present invention reduce the enthalpy of the steam upstream of the inlet valve 115 , In addition, the pressure ratio across the inlet valve 115 be reduced. Together, these actions can collectively lower the temperature inside the HP case 125 reduce. In one embodiment of the present invention, the temperature reduction across the inlet valve 115 from about 69.4 ° C to 83.3 ° C (125 ° F to about 150 ° F). In comparison, this can be combined with 2 provide only a temperature reduction of approximately 27.8 ° C (50 ° F). The increased temperature reduction that can be provided by one embodiment of the present invention can reduce the vapor / metal temperature mismatch and thus reduce rotor loading.

5 is a record 500 , the operating curves according to the procedure 300 from 3 and 400 from 4 in accordance with embodiments of the present invention. A first vertical axis represents temperature (in ° F) and pressure (in psia). A second vertical axis represents the load (in percent). The first and second vertical axes are plotted over the startup time (in minutes) on the horizontal axis. The data series 505 represents the actual HP rotor load and the data series 510 represents the permissible load limit. The data series 515 and 520 represent the HP inlet pressure or temperature. The entrance area can be to the entry point 130 in 1 adjoin. The data series 525 may be the HP case temperature shown on the HP case 125 in 1 represent.

5 represents the HP rotor load 505 during the entire startup of the steam turbine 100 not the permissible load limit 510 exceeded. Here was the bypass valve 110 controlled the pressure at the inlet 130 to increase to approximately 1400 psig. In 5 is the HP case temperature 525 approximately 299 ° C (575 ° F). In contrast, the HP case temperature of 2 approximately 385 ° C (725 ° F). 5 also provides increases in HP inlet pressure and temperature 520 respectively. 525 because the inlet pressure 515 as described is reduced.

As those skilled in the art will appreciate, the many varying features and configurations described above with reference to the various exemplary embodiments may also be selectively applied to form the other possible embodiments of the present invention. Those skilled in the art will further appreciate that all possible repetitions of the present invention are not provided in detail or discussed, although all the combinations and possible embodiments included in the following claims or otherwise are intended to be part of the present application. In addition, those skilled in the art will recognize improvements, changes and modifications from the foregoing description of some exemplary embodiments of the invention. Such improvements, changes and modifications within the state of the art are also intended to be covered by the appended claims. Further, it should be understood that the foregoing relates only to the described embodiments of the present application, and that numerous changes and modifications can be made therein without departing from the spirit and scope of the application as defined by the following claims and their equivalents.

The present invention has the technical effect of reducing the start-up time associated with starting a steam turbine 100 , Embodiments of the present invention provide a novel method for reducing a vapor / metal temperature mismatch during start-up of a steam turbine 100 is present. In essence, embodiments of the invention may include the pressure of the steam upstream of a high pressure (HP) section 120 a steam turbine 100 associated inlet valve 115 increase. The initially high pressure of the steam can reduce the enthalpy of the steam and thereby the temperature of the HP section 120 reduce supplied steam.

LIST OF REFERENCE NUMBERS

100

steam turbine

105

HP Drum

110

bypass valve

115

intake valve

120

HP section

125

HP case

130

port of entry

135

outlet location

140

capacitor

200

presentation

205

HP rotor load

210

Permitted exposure limit

215

HP inlet pressure

220

HP inlet temperature

225

HP-housing temperature

300

method

400

method

500

presentation

505

HP rotor load

510

Permitted exposure limit

515

HP inlet pressure

520

HP inlet temperature

525

HP-housing temperature

Claims (10)

Procedure ( 300 . 400 ) for starting a power plant machine, the method ( 300 . 400 ) comprises the steps of: providing a steam turbine ( 100 ) configured to convert steam to mechanical torque; the steam turbine ( 100 ) an HP section ( 120 ) having; and increasing a vapor pressure upstream of an inlet valve ( 115 ) to a suitable print area ( 315 ), whereby the inlet valve ( 115 ) upstream of the HP section ( 120 ) is located; wherein the step of increasing the pressure of the vapor ( 115 ) a temperature of the steam before entering the HP section ( 120 ) decreased. Procedure ( 300 . 400 ) according to claim 1, further comprising the step of starting a startup process of the steam turbine ( 330 ), if a start-up condition is met ( 325 ). Procedure ( 300 . 400 ) according to claim 2, further comprising the step of opening the inlet valve ( 115 ) to allow steam to enter the HP section ( 345 ). Procedure ( 300 . 400 ) according to claim 2, further comprising the step of determining whether a rotor load is within an allowable range ( 350 ). Procedure ( 300 . 400 ) according to claim 4, further comprising the step of maintaining the instantaneous load on the steam turbine until the rotor load is within the allowable range ( 355 ). Procedure ( 300 . 400 ) according to claim 5, further comprising the step of reducing the vapor pressure upstream of the inlet valve (10). 115 . 360 ). Procedure ( 300 . 400 ) according to claim 6, further comprising the step of raising a temperature of the steam in an HP housing region ( 125 ) of the HP section ( 365 ). Procedure ( 300 . 400 ) according to claim 5, further comprising the step of increasing a temperature of the steam in an HP housing area ( 125 ) of the HP section ( 460 ). Procedure ( 300 . 400 ) according to claim 8, further comprising the step of reducing the vapor pressure upstream of the inlet valve (10). 115 . 465 ). Procedure ( 300 . 400 ) for starting a power plant with a steam turbine ( 100 ), the process ( 300 . 400 ) comprises the steps of: providing a steam turbine ( 100 ) configured to convert steam to mechanical torque; the steam turbine ( 100 ) an HP section ( 120 ) and a bypass system ( 110 ) having; Determine if a cold start of the steam turbine is required ( 410 ); Increasing a pressure of the steam upstream of an inlet valve ( 115 ) on a suitable printing area ( 415 ), whereby the inlet valve ( 115 ) upstream of the HP section ( 120 ) is located; Determine if the steam is upstream of the inlet valve ( 115 ) in the appropriate pressure range ( 420 ) is located; Starting a startup process of the steam turbine ( 430 ), if a start-up condition is met ( 425 ); and controlling the intake valve ( 115 ) so that there is steam in the HP section ( 120 ) 440 . 445 ) can flow; wherein the step of increasing the vapor pressure reduces a temperature of the vapor before the vapor enters the HP section ( 120 ) flows.

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