JP2012041823A - Valve device of steam turbine and operation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve device of a steam turbine that reduces manufacturing cost of the steam turbine and improves the efficiency, even when high temperature and high pressure working fluid is used.SOLUTION: The device includes: a first valve casing 11 which is attached to an upper part of a steam turbine casing 30 and forms a first main channel 17; a first valve seat 12 which is located in the first main channel 17; a first valve element 13 which is stored in the first valve casing 11 so as to be movable back and forth in a vertical direction to the first valve seat 12; a bypass channel 46 which is installed in the first valve element 13; a slave valve element 15 which is stored in the first valve element 13 so as to be movable back and forth in the vertical direction to an opening 45 and opens and closes the bypass channel 46; a second valve casing 21 which is attached at a lower part of the steam turbine casing 30 and forms a second main channel 27; a second valve seat 22 which is located in the second main channel 27; and a second valve element 23 which is stored in the second valve casing 21 so as to be movable back and forth in the vertical direction to the second valve seat 22.

Description

  The present invention relates to a steam turbine valve device for controlling a flow rate of steam supplied to a steam turbine casing and a method for operating the same.

  A valve device for adjusting the flow rate of steam supplied to a steam turbine casing of a thermal power generation facility or the like is usually installed in front of or on both sides of the steam turbine casing (steam turbine casing), and a reed pipe through which steam flows is provided. Via a steam turbine casing (see Patent Document 1 and the like). This type of valve device arrangement may be referred to as a separate arrangement.

  Further, as a valve device for a steam turbine in a low output band, there is a shell mount type structure in which valve devices are directly attached to the upper and lower sides of a steam turbine casing. As this type of valve device, for example, a valve casing is attached to each of a vertical upper side and a vertical lower side of a steam turbine casing, and two steam control valves are built in each of the valve casings. There is what constitutes the device. The main valve devices installed for steam turbine control in thermal power generation facilities include a main steam stop valve, a steam control valve, a reheat steam stop valve, and an intercept valve. The valve device having the adjustment function is a steam control valve and an intercept valve.

JP 2006-183582 A

  Incidentally, in recent years, there has been a demand for higher efficiency and lower cost of thermal power generation facilities, and higher efficiency and lower cost are required not only for steam turbines but also for valve devices that are accessory equipment. For example, when comparing the above-mentioned separately mounted structure and shell mount type structure for a valve device having a steam flow rate adjusting function, the shell mount type structure without a lead pipe has the advantage that the number of parts is smaller and the manufacturing cost is lower. is there. Furthermore, since the shell mount type has less heat loss due to the lead tube, higher efficiency can be expected. However, in recent years, high-temperature and high-pressure steam is sometimes used as the working fluid of the steam turbine, and it is necessary to consider that such steam is introduced into the valve device.

  An object of the present invention is to provide a steam turbine valve device and a method of operating the same that can reduce the manufacturing cost and increase the efficiency of a steam turbine even when a high-temperature and high-pressure working fluid is used.

  (1) In order to achieve the above object, the present invention provides a first main flow path that is attached to an upper portion of a steam turbine casing that forms a passenger compartment and communicates a steam outlet and a steam inlet connected to the passenger compartment. A first valve casing to be formed, a first valve seat installed in the first main flow path, and a first valve casing accommodated in the first valve casing so as to be movable back and forth in the vertical direction with respect to the first valve seat. A bypass which is a flow path provided in the first valve body, and communicates an opening provided in the first valve body and an upstream side of the first valve body in the first main flow path. A flow path, a subvalve element that opens and closes the bypass passage, and is accommodated in a lower portion of the steam turbine casing; Second main flow path communicating with the connected steam outlet and steam inlet A second valve casing to be formed, a second valve seat installed in the second main flow path, and a second valve casing housed in the second valve casing so as to be movable forward and backward with respect to the second valve seat. A valve body is provided.

  (2) In the above (1), preferably, the second main flow path further includes a temperature detection means for detecting a flow path surface temperature downstream of the second valve body.

  (3) In the above (2), preferably, the temperature detecting means is a first temperature detector installed in the second valve casing so as to be positioned in the vicinity of the second valve seat, or the second The second temperature detector is installed in the second valve casing so as to be positioned in the vicinity of the flow path on the downstream side of the second valve seat in the main flow path.

  (4) In any one of the above (1) to (3), preferably, the steam turbine casing includes an upper casing and a lower casing, and the upper casing and the lower casing are flange portions installed in a substantially horizontal direction. It shall be concluded via.

  (5) Further, in order to achieve the above object, the present invention provides a first valve body that is installed to be movable in the vertical direction with respect to the first valve seat that is installed in the upper opening of the steam turbine casing. A sub-valve body that is installed in a bypass flow path that communicates the upper opening and the upstream side of the first valve body, and that opens and closes the bypass flow path; and a second valve body that is installed in the lower opening of the steam turbine casing. In a method for operating a valve device of a steam turbine comprising a second valve body that is installed so as to be able to advance and retreat in a vertical direction with respect to two valve seats, a procedure for opening the bypass flow path by moving the child valve body, After opening the bypass flow path, the procedure of separating the first valve body from the first valve seat, and the surface temperature of the second valve seat after separating the first valve body from the first valve seat If it is estimated that the temperature is equal to or higher than the saturated steam temperature, the second valve body is removed from the second valve seat. Shall and a procedure for between.

  According to the present invention, it is possible to reduce the manufacturing cost and increase the efficiency of the steam turbine.

1 is a structural diagram of a valve device for a steam turbine according to an embodiment of the present invention. The enlarged view of the 1st valve casing 11 vicinity in FIG. The enlarged view of the 2nd valve casing 21 vicinity in FIG. The enlarged view of the 2nd valve body 13A at the time of incorporating the child valve body 15A. The top view of the valve apparatus of the stand-alone type structure which is a comparative example of embodiment of this invention. The structural diagram of the valve device of the shell mount type structure which is a comparative example of embodiment of this invention. The internal structure figure of the upper valve casing 83 in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a structural diagram of a valve device for a steam turbine according to an embodiment of the present invention. The valve device of the steam turbine shown in this figure is formed with a shell mount structure, and includes a first valve casing 11, a first valve seat 12, a first valve body 13, a second valve casing 21, and a second valve casing. A valve seat 22 and a second valve body 23 are provided.

  The first valve casing 11 is directly attached to the upper part of the steam turbine casing 30 forming the casing 1, and is connected to a steam outlet connected to the casing 1 and steam generating means (not shown) such as a boiler. A first main channel 17 communicating with the steam inlet is formed in the interior. The steam turbine casing 30 is divided into two in the axial direction of the steam turbine and includes an upper casing 31 and a lower casing 32. The upper casing 31 and the lower casing 32 are fastened via flange portions 33 installed at both ends in the substantially horizontal direction.

  The first valve seat 12 is formed in an annular shape, and is installed in the first main flow path 17 in the first valve casing 11. The first valve body 13 adjusts the flow rate of steam supplied to the passenger compartment 1 by moving in the vertical direction so as to be seated or separated from the first valve seat 12 (steam control valve). Is housed in the first valve casing 11 so as to be movable back and forth in the vertical direction.

  FIG. 2 is an enlarged view of the vicinity of the first valve casing 11 in FIG. In FIG. 2, a sleeve 41 is a cylindrical member fixed in the first valve casing 11 so as to surround the first valve body 13, and the first valve body 13 slides in the sleeve 41. A valve stand 42 is inserted above the first valve body 13 in the inner peripheral portion of the sleeve 41. Inside the valve stand 42, a valve rod (first valve rod) 43 integrated with the child valve body 15 is passed. The valve stem 43 is appropriately driven in the vertical direction by a driving device (not shown). If the child valve body 15 is provided in the first valve body 13 in this way, the valve diameter of the first valve body 13 can be easily increased. Therefore, for example, application to a high-power turbine becomes easy.

  The first valve body 13 is provided with a hole 44 through which the child valve body 15 and the valve rod 43 are passed. The hole 44 is a surface of the first valve body 13 facing the first valve seat 12 (in FIG. 2). It is exposed to the outside through an opening 45 provided on the lower end surface. The opening 45 communicates with the upstream side of the first valve body 13 in the first main flow path 17 (that is, the outside of the sleeve 41) through the hole 44 through the gap between the first valve body 13 and the sleeve 41. Thus, a bypass channel (chamber) 46 that connects the first main channel 17 to the vehicle compartment 1 is formed.

  The child valve body 15 opens and closes the bypass flow path 46 by being seated or separated inside the opening 45 that is the valve seat, and is housed in the first valve body 13 so as to be able to advance and retreat with respect to the opening 45. Has been. Protrusions 47 and 48 are provided on the outer peripheral portion of the valve rod 43 and the inner peripheral portion of the first valve body 13, respectively. For example, when the valve element 15 is pulled up by the valve rod 43 from the state where the child valve body 15 is seated in the opening 45, first, the bypass flow path 46 is opened and communicates with the vehicle compartment 1. Thereafter, when the valve rod 43 is further lifted, the protruding portion 47 of the valve rod 43 is engaged with the protruding portion 48 of the first valve body 13 to lift the first valve body, and the first flow path 17 is connected to the compartment 1. Communicate.

  A drain pipe 18 is connected to the first valve casing 11. A drain valve 19 is attached to the drain pipe 18. The first valve casing 11 is warmed up for the purpose of relaxing the thermal stress generated in the first valve casing 11 when the turbine is started. This warm-up is performed by opening the drain valve 19 with the first valve body 13 seated on the first valve seat and discharging the steam in the first valve casing 11. Thereby, since the drain which generate | occur | produced in the 1st valve casing 11 is discharged | emitted outside via the drain pipe 18, it can prevent that a drain flows in into the compartment 1 at the time of a steam turbine starting.

  Returning to FIG. 1, the second valve casing 21 is directly attached to the lower part of the steam turbine casing 30 that forms the casing 1, and steam generating means (not shown) such as a steam outlet and a boiler connected to the casing 1. The second main flow path 27 communicating with the steam inlet connected to (1) is formed therein.

  The second valve seat 22 is formed in an annular shape, and is installed in the second main flow path 27 in the second valve casing 21. The second valve element 23 adjusts the flow rate of steam supplied to the passenger compartment 1 by moving in the vertical direction so as to be seated or separated from the second valve seat 22 (steam control valve). Is housed in the second valve casing 21 so as to be movable back and forth in the vertical direction.

  FIG. 3 is an enlarged view of the vicinity of the second valve casing 21 in FIG. As shown in this figure, unlike the first valve body 13, the second valve body 23 is a type of valve that does not have a child valve body therein. A valve rod (second valve rod) 26 is attached to the lower end of the second valve body 23. The valve stem 26 is appropriately driven in the vertical direction by a driving device (not shown), whereby the second valve body 23 is moved in the vertical direction.

  A first thermocouple (first temperature detector) 51 is provided in the second valve casing 21 as temperature detection means for detecting the surface temperature of the flow path located downstream of the second valve body 23 in the second main flow path 27. And the 2nd thermocouple (2nd temperature detector) 52 is attached. Among these, the first thermocouple 51 is used for estimating the surface temperature of the second valve seat 22, and is housed in a recess extending to the vicinity of the second valve seat 22 in the second valve casing 21. ing. On the other hand, the second thermocouple 52 is used to estimate the surface temperature of the flow path downstream of the second valve seat 22 in the second main flow path 27, and the second valve seat in the second main flow path 27. 22 is housed in a recess that extends to the vicinity of the flow path downstream of 22.

  In the present embodiment, the two thermocouples 51 and 52 are attached to the second valve casing 21 from the viewpoint of improving the detection accuracy of the surface temperature of the flow channel located downstream from the second valve body 23. From the viewpoint of estimating the surface temperature of the second valve seat, it is sufficient to install either one of the thermocouples. In the present embodiment, the two thermocouples 51 and 52 are installed in the vicinity of the second valve seat 22 and the second main flow path 27, respectively, in order to easily seal the steam. That is, the structure in which the second valve casing 21 is provided with a through hole and the thermocouples 51 and 52 are attached makes it difficult to seal the steam.

  A drain pipe 28 is connected to the second valve casing 21. A drain valve 29 is attached to the drain pipe 28. Similarly to the first valve casing 11, when the turbine is started, the drain valve 29 is opened while the second valve body 23 is seated on the second valve seat 22, so that the steam in the second valve casing 21 is discharged. The second valve casing 21 can be warmed up.

  Here, before explaining the operation and action of the valve device according to the present embodiment, first, in order to facilitate understanding of the effect exhibited by the present embodiment, a subvalve is attached to the second valve body 23. The case where it is built in will be described. FIG. 4 is an enlarged view of the second valve body 13A when the child valve body 15A is incorporated. The second valve element 13A shown in this figure has a valve element 15A. Each component of the second valve body 13A corresponds to a component obtained by inverting the components of the first valve body 13 upside down, and a subscript A is added to distinguish it from each component of the first valve body 13. ing.

  As shown in FIG. 4, when the child valve body 15A is built in the second valve body 13A, gravity acts on the second valve body 13A in the same direction as the valve opening direction (ie, vertically downward). Therefore, when the differential pressure between the upstream side (the pressure in the second valve casing 21) and the downstream side (the pressure in the compartment 1) of the second valve body 13A is smaller than the weight of the second valve body 13A, the valve stem If 43 A is pulled down and the subvalve body 15A is separated from the opening 45A, the second valve body 13A may fall down unintentionally following this. In this case, the second valve body 13A may move regardless of the control of the valve rod 43A. Therefore, the control characteristics of the second valve body 13A are determined according to the pressure difference between the upstream side and the downstream side of the second valve body 13A. Will change. That is, since the opening degree of the second valve body 13A cannot be freely controlled regardless of the pressure, it is difficult to employ such a structure from the viewpoint of control. Therefore, in the present embodiment, from the viewpoint of freely controlling the opening degree of the second valve body 23 regardless of the pressure, the second valve body 23 installed on the lower side of the steam turbine casing 30 has a child valve body. Not built-in.

  Next, the operation and action of the valve device according to the present embodiment will be described. In the valve device according to the present embodiment configured as described above, before starting the steam turbine, first, the first valve body 13 and the second valve body 23 are replaced with the first valve seat 12 and the second valve seat. The drain valve 19 and the drain valve 29 are opened in a state where they are seated on the 22, and the steam is discharged out of the first main flow path 17 and the second main flow path 27 via the drain pipe 18 and the drain pipe 28. The valve casing 11 and the second valve casing 21 are warmed up. Thereafter, when the warm-up of the first valve casing 11 and the second valve casing 21 is completed, the drain valve is left with the first valve body 13 and the second valve body 23 being seated on the first valve seat 12 and the second valve seat 22. 19 and the drain valve 29 are closed, and the steam is guided into the first main flow path 17 and the second main flow path 27.

  As described above, when the first valve body 13 and the valve body 15 are seated on the first valve seat 12 and the opening 45 and the steam is guided into the first main flow path 17, A force resulting from the pressure difference between the upstream side and the downstream side (vehicle compartment 1 side) acts on the first valve body 13 in the closing direction. Therefore, a large driving force is required to open the first valve body 13 in this state. Therefore, when starting the steam turbine, first, the first valve rod 43 is pulled up to separate the child valve body 15 from the opening 45 of the first valve body 13 and open the bypass flow path 46. When the child valve body 15 is separated from the opening 45 in this way, the bypass flow path 46 communicates with the vehicle compartment 1 via the opening 45, so that the pressure difference between the upstream side and the downstream side of the first valve body 13 is reduced. Decrease. When the first valve rod 43 is further pulled up in this state, the projecting portion 47 is locked to the projecting portion 48 of the first valve body 13, and the first valve body 13 rises together with the first valve rod 43. When the first valve body 13 is separated from the first valve body 13, the first main flow path 17 is communicated with the passenger compartment 1, and the steam flow rate to the steam turbine is adjusted according to the opening degree of the first valve body 13.

  As described above, when the first valve body 13 is opened, the second valve body 23 is held while being seated on the second valve seat 22. This is because the second valve body 23 does not include the child valve body 15 for reducing the valve opening force unlike the first valve body 13, and the steam in the vehicle compartment 1 is insufficient due to insufficient valve opening force of the driving device. This is because the second valve body 23 cannot be opened unless the pressure rises to a predetermined value. Therefore, steam is introduced into the passenger compartment 1 via the first casing 11, and the interior of the passenger compartment 1 is reached to a value that allows the movement of the second valve body 23 (hereinafter sometimes referred to as “openable pressure”). The second valve body is opened after increasing the pressure of. As a result, even when high-temperature and high-pressure steam is used as the working fluid, the steam flow rate can be adjusted only by the two valve bodies 13 and 23, so that the manufacturing cost of the steam turbine can be reduced. The efficiency of the steam turbine can also be increased.

  Next, another effect exerted by the present embodiment will be described while a structure having a structure different from that of the valve device according to the present embodiment is described as a comparative example.

  FIG. 5 is a top view of a valve device having a separate structure, which is a comparative example of the embodiment of the present invention. The valve device shown in this figure has four steam stop valves 61, 62, 63, 64 installed at the same height, and four steam controls installed at the same height on the downstream side of these valves 61-64. Valves 65, 66, 67 and 68 are provided. Each of the steam stop valves 61 to 64 is connected to the adjacent steam stop valves 61 to 64 through a flow path 69. Further, these eight steam valves 61 to 68 are installed in front of the steam turbine casing (steam turbine casing) 70 (left direction in FIG. 5), and each of the steam valves 61 to 68 includes four lead pipes. A steam turbine casing 70 is connected via 71. Specifically, the lead pipe 71 connected to the steam stop valve 61 and the steam control valve 65 and the lead pipe 71 connected to the steam stop valve 64 and the steam control valve 68 are connected to the steam turbine casing 70 from below. The reed pipe 71 connected to the steam stop valve 62 and the steam control valve 66 and the reed pipe 71 connected to the steam stop valve 63 and the steam control valve 67 are connected to the steam turbine casing 70 from above. .

  FIG. 6 is a structural view (front view) of a valve device of a shell mount type structure that is a comparative example of the embodiment of the present invention. In this figure, the steam control valves 81 and 82 are installed vertically above the steam turbine casing 70 and are built in a common valve casing 83. On the other hand, the steam control valves 84 and 85 are installed vertically below the steam turbine casing 70 and are built in a common valve casing 86. FIG. 7 is an internal structural diagram of the upper valve casing 83 in FIG. 6. The valve body of the steam control valve 82 in the valve casing 83 is in a closed state, and the valve body of the steam control valve 81 is in an open state. ing.

  By the way, in general, during the start-up process and operation of the steam turbine, each steam control valve controls the steam flow rate by adjusting its opening according to the load control of the turbine. May be fully closed. For example, in the separate type structure configured as shown in FIG. 5, even if any of the steam control valves 65 to 68 is fully closed, the steam stop valves 61 to 64 are connected by the flow path 69. Steam convection occurs in the casings of the control valves 65-68. Therefore, even if any of the steam control valves 65 to 68 is fully closed, the surface temperature of the fully closed control valve does not decrease, and the drain does not accumulate. On the other hand, in the shell mount type structure configured as shown in FIG. 6, when the valve body of the steam control valve 82 in the valve casing 83 is closed as shown in FIG. 7, the valve body of the steam control valve 81 is open. Therefore, steam convection always occurs in the valve casing 83. Therefore, as in the case of FIG. 5, even if any of the steam control valves 81 and 82 is fully closed, the surface temperature of the fully closed control valve does not decrease, and the drain does not accumulate. ing.

  In contrast, in the valve device according to the present embodiment, when the first valve body 13 is opened and the second valve body 23 is held closed when the steam turbine is started, the inside of the second valve casing 21 is maintained. The steam remains stagnant. Therefore, the surface temperatures of the second valve body 23 and the second valve seat 22 are less likely to rise compared to the first valve body 13, the first valve seat 12, the steam turbine casing 30, and the like that have steam flow. On the other hand, in a state in which the first valve body 13 is opened and the second valve body 23 is closed, the downstream side of the second valve body 23 (the upper part of the second valve body 23) is the lowest point of the vehicle compartment 1. Therefore, the steam from the vehicle compartment 1 comes into contact with the second valve body 23 and the second valve seat 22 having a relatively lower temperature than the other portions, and a drain pool is generated downstream of the second valve body 23. There is a case.

  Therefore, in the present embodiment, the first thermocouple 51 and the second thermocouple 52 are attached to the second valve casing 21. That is, the surface temperature of the second valve seat 22 is estimated based on the detected temperatures of these two thermocouples 51 and 52, and it is monitored whether or not the estimated temperature is equal to or higher than the saturated steam temperature.

  Therefore, when the pressure in the passenger compartment 1 rises to the valve opening possible pressure and it is confirmed that the estimated temperature of the second valve seat 22 is equal to or higher than the saturated steam temperature, the second valve body 23 is opened. Thus, steam can be introduced into the passenger compartment 1. On the other hand, although the pressure in the passenger compartment 1 has increased to a valve-openable pressure, if the estimated temperature is lower than the saturated steam temperature, there is a possibility that a drain pool has occurred. Therefore, the drain valve 29 is opened to allow high-temperature steam to flow through the second valve casing 21, and the temperatures of the second valve body 23 and the second valve seat 22 are raised. Then, after the estimated temperature of the second valve seat 22 is raised to the saturated steam temperature or higher, the drain valve 29 is closed again and the second valve body 23 is opened. Steam can be introduced. Therefore, according to the present embodiment, in the shell mount type structure in which one valve is arranged above and below the steam turbine casing 1, the valve is opened in a state where a drain pool is generated in the downstream area of the lower valve. Therefore, the reliability of the steam turbine can be improved.

DESCRIPTION OF SYMBOLS 1 Cabin 11 1st valve casing 12 1st valve seat 13 1st valve body 15 Child valve body 17 1st main flow path 21 2nd valve casing 22 2nd valve seat 23 2nd valve body 26 Valve rod 27 2nd main flow path 30 Steam Turbine Casing 44 Hole 45 Opening 46 Bypass Channel 47, 48 Projection 51, 52 Thermocouple

Claims (5)

A first valve casing that is attached to an upper portion of a steam turbine casing that forms a passenger compartment, and that forms a first main flow path that connects the steam outlet and the steam inlet connected to the passenger compartment;
A first valve seat installed in the first main flow path;
A first valve body housed in the first valve casing so as to be movable back and forth in the vertical direction with respect to the first valve seat;
A flow path provided in the first valve body, the bypass flow path communicating the opening provided in the first valve body and the upstream side of the first valve body in the first main flow path;
A child valve body that is housed in the first valve body so as to be movable back and forth in the vertical direction with respect to the opening, and opens and closes the bypass passage;
A second valve casing which is attached to a lower portion of the steam turbine casing and forms a second main flow path communicating with a steam outlet and a steam inlet connected to the vehicle compartment;
A second valve seat installed in the second main flow path;
A steam turbine valve device comprising: a second valve body housed in the second valve casing so as to be capable of moving back and forth in the vertical direction with respect to the second valve seat. The steam turbine valve device according to claim 1,
The steam turbine valve device further comprising temperature detection means for detecting a flow path surface temperature downstream of the second valve body in the second main flow path. The valve device for a steam turbine according to claim 2,
The temperature detecting means is a first temperature detector installed in the second valve casing so as to be positioned in the vicinity of the second valve seat, or a downstream side of the second valve seat in the second main flow path. A steam turbine valve device, being a second temperature detector installed in the second valve casing so as to be positioned in the vicinity of a flow path. The steam turbine valve device according to any one of claims 1 to 3,
The steam turbine casing includes an upper casing and a lower casing,
The said upper casing and the lower casing are fastened via the flange part installed in the substantially horizontal direction, The valve apparatus of the steam turbine characterized by the above-mentioned. A first valve body installed to be able to advance and retreat in a vertical direction with respect to a first valve seat installed in an upper opening of the steam turbine casing, and communicates the upper opening and the upstream side of the first valve body. A secondary valve body that is installed in the bypass flow path and opens and closes the bypass flow path, and a second valve seat that is movable in the vertical direction with respect to a second valve seat that is installed in the lower opening of the steam turbine casing. In a method for operating a valve device of a steam turbine comprising a valve body,
Opening the bypass flow path by moving the valve element,
A procedure for separating the first valve body from the first valve seat after opening the bypass flow path;
If it is estimated that the surface temperature of the second valve seat is equal to or higher than the saturated steam temperature after the first valve body is separated from the first valve seat, the second valve body is separated from the second valve seat. A method for operating a valve device for a steam turbine.

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