JP4864838B2 - Steam valve - Google Patents

Description

  The present invention relates to a steam valve used in a steam turbine plant, and more particularly to a steam valve that prevents foreign particles from accumulating between a valve stem and a valve stem bush.

  As shown in FIG. 6, a steam turbine plant conventionally includes a generator 1, a turbine shaft 2 connected to a rotating shaft of the generator 1, and a boiler 6. A high-pressure steam turbine 3 that receives high-pressure steam sent from a boiler 6 is attached to the turbine shaft 2. Further, the intermediate pressure of the turbine shaft 2 that has finished the expansion work in the turbine stage of the high-pressure steam turbine 3, is reheated by the reheater 7 of the boiler 6, and receives the reheated steam. A steam turbine 4 is attached. Further, a low-pressure steam turbine 5 that receives low-pressure steam that has finished expansion work in the turbine stage of the intermediate-pressure steam turbine 4 is attached to the turbine shaft 2. Such a steam turbine plant is of a so-called three-casing axial flow type.

  Moreover, the high-pressure steam turbine 3, the intermediate-pressure steam turbine 4, and the low-pressure steam turbine 5 each have a large number of turbine stages (not shown) that combine turbine nozzles and turbine blades along the axial direction of the turbine shaft 2. is doing.

  In the steam turbine plant shown in FIG. 6, the high-pressure steam generated in the boiler 6 is first sent to the high-pressure steam turbine 3 to perform expansion work in the turbine stage of the high-pressure steam turbine 3, and the pressure of the steam decreases. Next, the medium-pressure steam sent out from the high-pressure steam turbine 3 is sent to the reheater 7 of the boiler 6, heated again, sent to the intermediate-pressure steam turbine 4, and the turbine stage of the intermediate-pressure steam turbine 4. The expansion work is performed in the steam, and the pressure of the steam drops. Next, the low-pressure steam sent out from the intermediate-pressure steam turbine 4 is sent to the low-pressure steam turbine 5 and performs expansion work in the turbine stage of the low-pressure steam turbine 5, and the pressure of the steam further decreases. As the steam performs expansion work in this way, the turbine shaft 2 rotates and the generator 1 is driven. Thereafter, the steam is sent to the condenser 8 to be condensed and sent to the boiler 6.

  Moreover, as shown in FIG. 6, such a steam turbine plant has many steam valves. That is, a main steam stop valve 9 is provided between the boiler 6 and the high-pressure steam turbine 3, and a steam control valve 10 is provided between the main steam stop valve 9 and the high-pressure steam turbine 3. A reheat steam stop valve 11 is provided between the reheater 7 of the boiler 6 and the intermediate pressure steam turbine 4, and an intercept valve 12 is provided between the reheat steam stop valve 11 and the intermediate pressure steam turbine 4. It has been. Such a steam valve has a relatively large structure because a large amount of high-pressure (for example, 16.6 MPa or 24.1 MPa) and high-temperature (for example, 538 ° C. or 566 ° C.) steam flows therein.

  In addition, the main steam stop valve 9, the steam control valve 10, the reheat steam stop valve 11, and the intercept valve 12 are arranged in parallel so as to form at least two rows, respectively, in an emergency or unexpected situation. It is possible to respond.

  The steam turbine plant also includes a speed governor 13 for controlling the main steam stop valve 9 and the intercept valve 12, and an emergency speed governor 14 for controlling the steam control valve 10 and the reheat steam stop valve 11. Have.

  The main steam stop valve 9 is mainly an ON-OFF type. When starting the steam turbine plant, the main steam stop valve 9 opens a sub-valve (not shown) incorporated in the main valve provided in the valve casing of the main steam stop valve 9, and steam that flows into the high-pressure steam turbine 3. The main valve is opened when a predetermined load is reached. Further, when an accident occurs in the power system and the load is shut off urgently based on a command issued from the governor 13, the main steam stop valve 9 closes the main valve and the subvalve of the valve body.

  The steam control valve 10 includes a plurality of valve bodies. The steam control valve 10 opens the plurality of valve bodies in accordance with the output (load) of the steam turbine plant, and controls the flow rate of the steam flowing into the high-pressure steam turbine 3. Further, when the valve is fully closed from the fully open state in an emergency such as when the load is interrupted, the steam control valve 10 receives all the commands issued from the emergency governor 14 and closes all the valve bodies.

  The reheat steam stop valve 11 is an ON-OFF type. When an emergency such as when the load is interrupted is required and the valve is fully closed from the fully open state, the reheat steam stop valve 11 receives a command issued from the emergency governor 14 and is preceded by the steam control valve 10. Close body. As a result, the steam sent from the reheater 7 is quickly cut off, and the turbine shaft 2 is prevented from rotating any further.

  The intercept valve 12 is also an ON-OFF type. When an emergency such as when the load is shut off is required and the valve is fully closed from the fully open state, the intercept valve 12 receives a command issued from the governor 13 and opens the valve body before the main steam stop valve 9. close. As a result, the steam sent from the reheater 7 is quickly cut off, and the turbine shaft 2 is prevented from rotating any further.

  Next, the reheat steam stop valve 11 will be described in further detail. As shown in FIG. 7, the reheat steam stop valve 11 includes a valve casing 15 including a steam inlet and an outlet (both not shown), a valve bottom cover 25 provided on one surface of the valve casing 15, and a valve casing. 15, and has a plate-like disk 16 that can freely come into contact with a valve seat (not shown) in the valve casing 15. A support shaft 19 is connected to the disk 16 via an arm 17, and a bearing flange 18 that rotatably supports the support shaft 19 is fixed to the valve casing 15. Further, a valve stem 21 is connected to the support shaft 19 via a connecting piece 20, an oil cylinder 24 that drives the valve stem 21 in the axial direction is connected to the valve stem 21, and the oil cylinder 24 is connected to the valve bottom cover 25. It is fixed. Further, a valve stem guide piece 23 is fixed to a penetrating portion of the valve bottom cover 25 through which the valve stem 21 passes, and a valve stem bush 22 is provided between the valve stem guide piece 23 and the valve stem 21.

  When the reheat steam stop valve 11 is fully opened from the fully closed state, first, the oil cylinder 24 is driven to move the valve rod 21 upward. As the valve stem 21 moves upward, the support shaft 19 connected to the valve stem 21 via the connecting piece 20 rotates in the direction of the arrow E1 in FIG. The connected disc 16 opens in the direction of the back side of the paper surface shown in FIG. As a result, the reheat steam stop valve 11 is fully opened. Therefore, the steam that flows in from the inlet of the valve casing 15 passes through the valve casing 15, is sent out from the outlet of the valve casing 15, and is sent to the intermediate pressure steam turbine 4.

  On the other hand, when the reheat steam stop valve 11 is fully closed from the fully open state, the pressure oil filled in the oil cylinder 24 is discharged. As a result, the support shaft 19 rotates in the direction of the arrow E2 opposite to the arrow E1, the disk 16 is brought into contact with a valve seat (not shown) in the valve casing 15, and the reheat steam stop valve 11 is Close completely.

  Next, the intercept valve 12 will be described in further detail. As shown in FIG. 8, the intercept valve 12 is provided in the valve casing 26 including a steam inlet 41 and an outlet 43, a valve bottom lid 34 provided on one surface of the valve casing 26, and the valve casing 26. And a valve seat 39. Further, an intercept main valve 29 that can come into contact with the valve seat 39 is provided in the valve casing 26, and an intercept sub-valve 28 that can come into contact with the inside of the intercept main valve 29 is provided inside the intercept main valve 29. ing. Among these, a balance chamber 35 is formed inside the intercept main valve 29, and a passage 40 that communicates the balance chamber 35 and the outlet 43 of the valve casing 29 is provided in the intercept main valve 29.

  In addition, a valve rod 30 that passes through the valve bottom cover 34 and is movable with respect to the valve bottom cover 34 is connected to the intercept sub-valve 28. An oil cylinder 33 that drives the valve stem 30 in the axial direction is connected to the valve stem 30, and the oil cylinder 33 is fixed to the valve bottom cover 34. Further, a valve stem guide piece 32 is fixed to a penetrating portion of the valve bottom lid 34 through which the valve stem 30 passes, and a valve stem bush 31 is provided between the valve stem guide piece 32 and the valve stem 30.

  Further, a valve canopy 37 is provided on the upper portion of the valve casing 26, and a balance chamber sleeve 38 is provided on the lower surface of the valve canopy 37. A seal ring 36 that contacts the inner peripheral surface of the balance chamber sleeve 38 is attached to the outer peripheral surface of the intercept main valve 29, and the intercept main valve 29 is slidable with respect to the balance chamber sleeve 38. A strainer 27 including an inlet 42 through which steam passes is provided in the valve casing 26.

  When the intercept valve 12 is fully opened from the fully closed state, first, the oil cylinder 33 is driven to move the valve stem 30 upward, and the intercept sub-valve 28 connected to the valve stem 30 serves as the intercept main valve. It moves away from the inner surface of 29 and moves upward. As a result, the passage 40 provided in the intercept main valve 29 is opened. For this reason, the steam flowing in from the inlet 41 of the valve casing 26 flows into the balance chamber 35 of the intercept main valve 29 through the inlet 42 of the strainer 27 provided in the valve casing 26, and the passage of the intercept main valve 29. 40 passes through the outlet 43 of the valve casing 26 and is sent to the intermediate pressure steam turbine 4. Thus, a large amount of steam is not instantaneously supplied to the intermediate pressure steam turbine 4 by passing through the passage 40 having a relatively narrow flow path. For this reason, it is possible to prevent a thermal shock from being applied to the intermediate pressure steam turbine 4.

  Next, when the intermediate pressure steam turbine 4 reaches a predetermined output, the intercept valve 12 further drives the oil cylinder 33 to move the valve stem 30 upward, and the intercept sub-valve 28 connected to the valve stem 30. Moves upward. Next, the intercept sub-valve 28 moves further upward, so that the intercept sub-valve 28 comes into contact with the upper part of the intercept main valve 29. Next, the intercept main valve 29 in contact with the intercept sub-valve 28 moves away from the valve seat 39 and moves upward. As a result, the intercept main valve 29 is opened and the intercept valve 12 is fully opened. Therefore, the steam flowing in from the inlet 41 of the valve casing 26 is sent from the outlet 43 of the valve casing 26 through the inlet 42 of the strainer 27 provided in the valve casing 26 and sent to the intermediate pressure steam turbine 4. It will be.

  On the other hand, when the intercept valve 12 is fully closed from the fully opened state, the pressure oil filled in the oil cylinder 33 is discharged. In this case, first, the intercept sub-valve 28 moves downward together with the valve stem 30. Next, the intercept subvalve 28 moves further downward, so that the intercept subvalve 28 comes into contact with the inside of the intercept main valve 29. Next, the intercept main valve 29 in contact with the intercept subvalve 28 moves downward together with the intercept subvalve 28. Thereafter, the intercept main valve 29 comes into contact with the valve seat 39, and the intercept valve 12 is fully closed.

  As described above, when the load is interrupted and the emergency is required and the valve is fully closed from the fully open state, the reheat steam stop valve 11 and the intercept valve 12 close the valve body quickly, and the boiler 6 and the reheater 7 Shut off the supplied steam. This reliably prevents the turbine shaft 2 from rotating further.

  As shown in FIG. 9 (a), a valve stem back seat 44 having an inclined portion is provided on the outer peripheral surface of the valve stem 21 (30) of each steam valve, and the valve stem guide pieces 23, 32 A bush back sheet 45 having an inclined shape portion corresponding to the inclined shape portion of the valve stem back seat 44 is provided on the inner peripheral surface. While each steam valve is fully opened, the inclined shape portion of the valve stem back seat 44 and the inclined shape portion of the bush back seat 45 are in contact with each other. This prevents the steam from leaking outside through the gap between the valve stem 21 (30) and the valve stem guide pieces 23, 32.

  However, during the operation of the steam turbine plant, each steam valve is maintained in a fully open state, and each steam valve has a solid foreign matter such as an oxide scale separated from the boiler 6 and the reheater 7 together with the steam. Particles flow in. As shown in FIG. 9A, the foreign particles flowing into each steam valve are deposited on the upper portion of the bush back sheet 45 through the gap between the valve stem 21 (30) and the valve stem guide pieces 23 and 32. In such a state, when a valve test for opening and closing the valve body is performed and the valve body is closed, the valve stem back seat 44 and the bush back seat 45 are separated as shown in FIG. 9B. Therefore, the foreign particles deposited on the upper part of the bush back sheet 45 fall on the outer peripheral surface of the valve stem back sheet 44 through the gap between the bush back sheet 45 and the valve stem 21 (30).

  Next, as shown in FIG. 9C, when the valve body is opened, the valve stem back sheet 44 and the bush back sheet 45 come into contact with each other. For this reason, foreign particles are sandwiched between the valve stem back sheet 44 and the bush back sheet 45. As a result, steam leaks from between the valve stem back seat 44 and the bush back seat 45 to the outside, and a stick is generated when the valve stem 21 (30) moves, so that the valve stem 21 (30) is smoothly moved. It becomes difficult to move.

In order to cope with such a problem, a steam valve capable of preventing foreign particles from flowing into the gap between the valve stem and the valve stem guide piece is disclosed (for example, see Patent Document 1). Here, a passage through which steam passes is provided in the valve stem guide piece, and steam is ejected from between the valve stem and the valve stem bush toward the inside of the valve casing.
JP 2001-329803 A

  In general, in order to prevent foreign particles from accumulating in the gap between the valve stems 21 and 30 and the valve stem guide pieces 23 and 32, a valve that opens and closes the valve body in a state where the steam turbine plant is operating. I test regularly. The valve test is performed one by one among a plurality of steam valves. By performing this valve test, foreign particles accumulated in the gap between the valve stem and the valve stem bush can be removed.

  However, when a valve test is performed on one steam valve in a state where the steam turbine plant is in operation, the steam valve subject to the valve test may be completely closed unexpectedly. Even in this case, it is necessary to stabilize the output of the steam turbine plant using another steam valve. For this reason, when performing a valve test, it is necessary to reduce the output of the steam turbine plant to some extent. That is, the valve test can be performed when the steam turbine plant is operated with the output reduced to some extent. For this reason, the timing for performing the valve test is limited.

  The present invention has been made in consideration of the above points, and can perform a valve test without being restricted by the operating conditions of the steam turbine plant, and is deposited in a gap between the valve stem and the valve stem bush. It is an object of the present invention to provide a steam valve that can remove foreign particles.

  The present invention relates to a steam valve used in a steam turbine plant, a valve casing including a steam inlet and a steam outlet, a lid for closing an opening provided on one surface of the valve casing, and a valve casing. A valve body provided in the valve casing and freely contactable with the valve seat, a valve rod connected to the valve body, penetrating the lid and movably provided with respect to the lid, and a valve A first valve stem drive mechanism connected to the rod and driving the valve stem in the axial direction; a lid-side bush fixed to a penetrating portion of the lid through which the valve rod passes; and interposed between the lid-side bush and the valve stem A steam valve comprising: a valve stem bush provided movably with respect to the lid-side bush; and a valve stem bush drive mechanism coupled to the valve stem bush and driving the valve stem bush. It is.

  The present invention relates to a steam valve used in a steam turbine plant, a valve casing including a steam inlet and a steam outlet, a lid for closing an opening provided on one surface of the valve casing, and a valve casing. A valve body provided in the valve casing and freely contactable with the valve seat, a valve rod connected to the valve body, penetrating the lid and movably provided with respect to the lid, and a valve A first valve stem drive mechanism that is coupled to the rod and drives the valve stem in the axial direction; and a bush fixed to a penetrating portion of the lid through which the valve stem passes, and the valve stem rotates about the central axis The steam valve is characterized in that a second valve stem driving mechanism that rotates and drives the valve stem is further connected to the valve stem.

  According to the present invention, when the steam turbine plant is in operation, the foreign material particles accumulated in the gap between the valve stem and the valve stem bush are removed by rotating the valve stem bush using the valve stem bush drive mechanism. Can be removed. In this case, since the valve stem and the valve body are not moved in the axial direction, the open / close state of the steam valve is not affected. For this reason, regardless of the operating conditions of the steam turbine plant, foreign particles accumulated in the gap between the valve stem and the valve stem bush can be removed, and the valve stem can be smoothly moved in the axial direction.

  Further, according to the present invention, when the steam turbine plant is in operation, the valve stem is rotated around the central axis using the second valve stem drive mechanism, thereby accumulating in the gap between the valve stem and the bush. The removed foreign particles can be removed. In this case, since the valve stem and the valve body are not moved in the axial direction, the open / close state of the steam valve is not affected. Therefore, regardless of the operating conditions of the steam turbine plant, foreign particles accumulated in the gap between the valve stem and the bush can be removed, and the valve stem can be smoothly moved in the axial direction.

DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment Hereinafter, an embodiment of the invention will be described with reference to the drawings. Here, FIG. 1 is a diagram showing a first embodiment of the steam valve according to the present invention, and is a diagram showing a cross-sectional configuration of the steam valve in the present invention.

  First, the steam valve 50 in the present invention will be described with reference to FIG. Here, the steam valve 50 is intended for a main steam stop valve used in a steam turbine plant, but is also applicable to a valve having a relatively large diameter such as a steam control valve, a reheat steam stop valve, and an intercept valve. it can.

  As shown in FIG. 1, the steam valve (main steam stop valve) 50 includes a valve casing 51 including a steam inlet 52 and a steam outlet 53, and a lid that closes an opening 51 a provided on the upper surface of the valve casing 51. 54 and a valve seat 55 provided in the valve casing 51.

  A valve body 56 is provided in the valve casing 51, including a main valve 57 that can come into contact with the valve seat 55, and a sub-valve 58 that is provided inside the main valve 57 and can come into contact with the inside of the main valve 57. ing. Among these, a balance chamber 59 is formed inside the main valve 57, and a passage 60 that connects the balance chamber 59 and the outlet 53 of the valve casing 51 is provided in the main valve 57. Opened and closed. Further, a plurality of bolts 61 are attached to the main valve 57 from the outside so that the tip protrudes to the inside of the main valve 57, and the sub-valve 58 is a convex that can contact the tip of the bolt 61 of the main valve 57. A portion 62 is formed. Thus, when the sub valve 58 moves upward, the convex portion 62 of the sub valve 58 comes into contact with the tip of the bolt 61 of the main valve 57 so that the sub valve 58 and the main valve 57 move together. It has become.

  Further, a valve rod 63 that penetrates the lid 54 and is movable with respect to the lid 54 is connected to the auxiliary valve 58 of the valve body 56, and the valve rod 63 is driven to the valve rod 63 in the axial direction. A valve stem drive mechanism 64 is connected. Further, a lid-side bush 65 is fixed to the penetrating portion 54a of the lid 54 through which the valve rod 63 passes, and is movable in the circumferential direction with respect to the lid-side bush 65 between the lid-side bush 65 and the valve rod 63. A valve stem bush 66 is provided.

  As shown in FIG. 1, the valve stem bush 66 extends outward through the lid 54, and a gear portion 67 formed of a spur gear is provided at the outer end of the valve stem bush 66. Further, a spur gear 68 is engaged with the gear portion 67 of the valve stem bush 66, and a valve stem bush drive mechanism 69 that drives the valve stem bush 66 is connected to the gear 68. The valve stem bush drive mechanism 69 may be any one of a vapor pressure drive type, an electric drive type, and a hydraulic drive type.

  A first torque measuring means 70 is provided between the valve stem bush 66 and the valve stem bush drive mechanism 69, and the valve stem bush drive mechanism 69 corresponds to the torque value measured by the torque measure means 70. The driving force is variable. Alternatively, when the torque value measured by the first torque measuring means 70 becomes small, the driving by the valve rod bush drive mechanism 69 can be stopped.

  Next, the operation of the present embodiment having such a configuration will be described.

  When the steam valve 50 according to the present embodiment is fully opened from the fully closed state, first, the first valve rod driving mechanism 64 is driven to move the valve rod 63 upward, and the valve body 56 connected to the valve rod 63 is operated. The secondary valve 58 moves away from the inner surface of the main valve 57 of the valve body 56 and moves upward. As a result, the passage 60 provided in the main valve 57 is opened. For this reason, the steam flowing in from the inlet 52 of the valve casing 51 flows into the balance chamber 59 of the main valve 57, passes through the passage 60 of the main valve 57, and is sent out from the outlet 53 of the valve casing 51.

  Next, when the steam turbine reaches a predetermined output, the steam valve 50 further drives the first valve stem drive mechanism 64 to move the valve stem 63 upward, and the sub-valve 58 connected to the valve stem 63. Moves upward. Next, the convex portion 62 of the sub valve 58 comes into contact with the tip of the bolt 61 provided on the main valve 57. Next, the main valve 57 including the bolt 61 in contact with the convex portion 62 of the sub valve 58 moves away from the valve seat 55 together with the sub valve 58. As a result, the steam valve 50 is fully opened. For this reason, the steam flowing in from the inlet 52 of the valve casing 51 is sent out from the outlet 53 of the valve casing 51.

  On the other hand, when the steam valve 50 is fully closed from the fully opened state, first, the first valve rod drive mechanism 64 is driven so that the steam valve 50 is fully closed, and the sub valve 58 is moved downward together with the valve rod 63. . Next, the sub valve 58 moves further downward, so that the sub valve 58 comes into contact with the inside of the main valve 57. Next, the main valve 57 in contact with the sub valve 58 moves downward together with the sub valve 58. Thereafter, the main valve 57 contacts the valve seat 55. As a result, the steam valve 50 is fully closed.

  Further, when removing foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 of the steam valve 50 according to the present embodiment, first, the valve stem bush drive mechanism 69 is driven. As a result, the gear 68 made of a spur gear connected to the valve stem bush drive mechanism 69 rotates, and the driving force is transmitted to the gear portion 67 made of a spur gear engaged with the gear 68. It rotates in the circumferential direction with respect to the lid-side bush 65. Therefore, the foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 are finely crushed, and the foreign particles can be removed from the gap between the valve stem 63 and the valve stem bush 66.

  As described above, when removing foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66, the valve stem 63 and the valve body 56 are not moved in the axial direction. That is, the open / close state of the steam valve 50 is not affected. For this reason, foreign particles can be removed from the gap between the valve stem 63 and the valve stem bush 66 regardless of the open / closed state of the steam valve 50.

  In addition, according to the present embodiment, since the first torque measuring means 70 is provided between the valve stem bush 66 and the valve stem bush drive mechanism 69, the valve stem bush drive mechanism 69 performs the first torque measurement. The driving force can be changed in accordance with the torque value measured by the means 70. That is, the foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 are crushed and removed by rotating the valve stem bush 66 in the circumferential direction. During this time, the first torque measuring means 70 measures the driving force of the valve stem bushing drive mechanism 69, and when the torque value of the first torque measuring means 70 decreases, the foreign matter particles from the gap between the valve stem 63 and the valve stem bush 66. Therefore, the valve stem bush drive mechanism 69 can be stopped.

  In the present embodiment, the valve rod bush is rotated using the spur gear mechanism, but a worm gear may be adopted instead of the spur gear mechanism. In this case, the gear 68 may be replaced with a worm and the gear portion 67 may be replaced with a worm wheel.

  Thus, according to the present embodiment, the valve stem 63 and the valve stem bush 66 are rotated by rotating the valve stem bush 66 using the valve stem bush drive mechanism while the steam turbine plant is operating. The foreign particles accumulated in the gaps can be removed. In this case, since the valve stem 63 and the valve body 56 are not moved in the axial direction, the open / close state of the steam valve 50 is not affected. For this reason, it is possible to remove foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 regardless of the operating conditions of the steam turbine plant, and to smoothly move the valve stem 63 in the axial direction. Can do.

Second Embodiment Next, a second embodiment of the steam valve according to the present invention will be described with reference to FIG. Here, FIG. 2 is a figure which shows the cross-sectional structure of the steam valve in this invention.

  The steam valve 50 according to the second embodiment shown in FIG. 2 differs only in that a rack portion 71 is provided at the outer end of the valve stem bush 66 and a pinion 72 is connected to the valve stem bush drive mechanism 69. The other configuration is substantially the same as that of the first embodiment shown in FIG. In FIG. 2, the same parts as those of the first embodiment shown in FIG.

  According to the present embodiment, when removing foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 of the steam valve 50, first, the valve stem bush drive mechanism 69 is driven. As a result, the pinion 72 connected to the valve stem bush drive mechanism 69 rotates and the driving force is transmitted to the rack portion 71 engaged with the pinion 72, so that the valve stem bush 66 is axially connected to the lid side bush 65. Move in the direction. Therefore, the foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66 are finely crushed, and the foreign particles can be removed from the gap between the valve stem 63 and the valve stem bush 66.

  As described above, when removing foreign particles accumulated in the gap between the valve stem 63 and the valve stem bush 66, the valve stem 63 and the valve body 56 are not moved in the axial direction. That is, the open / close state of the steam valve 50 is not affected. For this reason, foreign particles can be removed from the gap between the valve stem 63 and the valve stem bush 66 regardless of the open / closed state of the steam valve 50.

Third Embodiment Next, a third embodiment of the steam valve according to the present invention will be described with reference to FIG. Here, FIG. 3 is a figure which shows the cross-sectional structure of the steam valve in this invention.

  In the steam valve 50 according to the third embodiment shown in FIG. 3, the valve stem 73 is rotatable about the central axis, and the second valve stem drive mechanism that rotationally drives the valve stem 73 to the valve stem 73. The only difference is that 77 is further connected, and the other configuration is substantially the same as that of the first embodiment shown in FIG. In FIG. 3, the same parts as those of the first embodiment shown in FIG.

  As shown in FIG. 3, a valve rod 73 is connected to the valve body 56 through the lid 54 and movable in the axial direction with respect to the lid 54, and rotatable about the central axis. In addition, a first valve stem drive mechanism 64 that drives the valve stem 73 in the axial direction is connected. In addition, a valve stem bush 74 is fixed to the penetrating portion 54a of the lid 54 through which the valve stem 73 passes.

  A gear portion 75 made of a spur gear is provided outside the valve casing 51 of the valve rod 73. A gear 76 made of a spur gear is engaged with the gear portion 75 of the valve rod 73, and a second valve rod drive mechanism 77 for driving the valve rod 73 is connected to the gear 76. The gear 76 may be replaced with a worm and the gear portion 75 may be replaced with a worm wheel. The second valve rod drive mechanism 77 may be any one of a vapor pressure drive type, an electric drive type, and a hydraulic drive type.

  Further, a second torque measuring means 78 is provided between the valve stem 73 and the second valve stem driving mechanism 77, and the second valve stem driving mechanism 77 has a torque value measured by the second torque measuring means 78. Correspondingly, the driving force is variable. Alternatively, when the torque value measured by the second torque measuring means 78 becomes small, the driving by the second valve rod drive mechanism 77 can be stopped.

  According to the present embodiment, when removing foreign particles accumulated in the gap between the valve stem 73 of the steam valve 50 and the valve stem bush 74, first, the second valve stem drive mechanism 77 is driven. As a result, the gear 76 made of a spur gear connected to the second valve rod drive mechanism 77 rotates, the driving force is transmitted to the gear portion 75 made of a spur gear engaged with the gear 76, and the valve rod 73 Rotate around the central axis. Therefore, the foreign particles accumulated in the gap between the valve stem 73 and the valve stem bush 74 are finely crushed, and the foreign particles can be removed from the gap between the valve stem 73 and the valve stem bush 74.

  Thus, when removing foreign particles accumulated in the gap between the valve stem 73 and the valve stem bush 74, the valve stem 73 and the valve body 56 are not moved in the axial direction. That is, the open / close state of the steam valve 50 is not affected. For this reason, foreign particles can be removed from the gap between the valve stem 73 and the valve stem bush 74 regardless of the open / closed state of the steam valve 50.

  Further, according to the present embodiment, since the second torque measuring means 78 is provided between the valve stem 73 and the second valve stem drive mechanism 77, the second valve stem drive mechanism 77 has the second torque. The driving force can be changed corresponding to the torque value measured by the measuring means 78. That is, the foreign particles accumulated in the gap between the valve stem 73 and the valve stem bush 74 are crushed and removed by rotating the valve stem bush 74 in the circumferential direction. During this time, the second torque measuring means 78 measures the driving force of the second valve stem driving mechanism 77, and when the torque value of the second torque measuring means 78 decreases, the second torque measuring means 78 detects foreign matter from the gap between the valve stem 73 and the valve stem bush 74. The second valve stem drive mechanism 77 can be stopped by determining that the particles have been removed.

Fourth Embodiment Next, a fourth embodiment of the steam valve according to the present invention will be described with reference to FIG. Here, FIG. 4 is a figure which shows the cross-sectional structure of the steam valve in this invention.

  The steam valve 50 according to the fourth embodiment shown in FIG. 4 is different in that an uneven shape is formed on the outer peripheral surface of the valve rod 79. Other configurations are the same as those of the first embodiment shown in FIG. It is almost the same as the form. In FIG. 4, the same parts as those of the first embodiment shown in FIG.

  As shown in FIG. 4, a valve rod 79 that passes through the lid 54 and is movable in the axial direction with respect to the lid 54 is connected to the valve body 56, and the valve rod 79 is driven in the axial direction to the valve rod 79. A first valve rod drive mechanism 64 is connected. Among these, an uneven shape is formed on the outer peripheral surface of the valve stem 79. In addition, a valve stem bush 74 is fixed to the penetrating portion 54a of the lid 54 through which the valve stem 79 passes.

  According to the present embodiment, an uneven shape is formed on the outer peripheral surface of the valve stem 79. As a result, foreign matter accumulated in the gap between the valve stem 79 and the valve stem bush 74 accumulates in the recesses on the outer peripheral surface of the valve stem 79 as the valve stem 79 moves in the axial direction. For this reason, it can prevent reliably that a foreign material particle is pinched | interposed into the clearance gap between the convex part of the valve stem 79, and the valve stem bush 74. FIG. As a result, the valve stem 79 can move smoothly in the axial direction.

Fifth Embodiment Next, a fifth embodiment of the steam valve according to the present invention will be described with reference to FIG. Here, FIG. 5 is a figure which shows the cross-sectional structure of the steam valve in this invention.

  The steam valve 50 in the fifth embodiment shown in FIG. 5 is different only in that an uneven shape is formed on the inner peripheral surface of the valve stem bush 80, and the other configuration is the first configuration shown in FIG. This is substantially the same as the embodiment. In FIG. 5, the same parts as those of the first embodiment shown in FIG.

  As shown in FIG. 5, a valve rod 63 that passes through the lid 54 and is movable in the axial direction with respect to the lid 54 is connected to the valve body 56, and the valve rod 63 is driven in the axial direction to the valve rod 63. A first valve rod drive mechanism 64 is connected. In addition, a valve stem bush 80 is fixed to the penetrating portion 54a of the lid 54 through which the valve stem 63 passes. An uneven shape is formed on the inner peripheral surface of the valve stem bush 80.

  According to the present embodiment, an uneven shape is formed on the inner peripheral surface of the valve stem bush 80. As a result, foreign matter accumulated in the gap between the valve stem 63 and the valve stem bush 80 is accumulated in the recess on the inner peripheral surface of the valve stem bush 80 as the valve stem 63 moves in the axial direction. For this reason, it can prevent reliably that a foreign material particle is pinched | interposed into the clearance gap between the valve stem 63 and the convex part of the valve stem bush 80. FIG. As a result, the valve stem 79 can move smoothly in the axial direction.

FIG. 1 is a diagram showing a cross-sectional configuration of a steam valve according to the first embodiment of the present invention. FIG. 2 is a diagram showing a cross-sectional configuration of the steam valve according to the second embodiment of the present invention. FIG. 3 is a diagram showing a cross-sectional configuration of the steam valve according to the third embodiment of the present invention. FIG. 4 is a diagram showing a cross-sectional configuration of the steam valve according to the fourth embodiment of the present invention. FIG. 5 is a diagram showing a cross-sectional configuration of the steam valve according to the fifth embodiment of the present invention. FIG. 6 is a diagram showing an outline of a conventional steam turbine plant. FIG. 7 is a view showing a cross-sectional configuration of a conventional reheat steam stop valve. FIG. 8 is a diagram showing a cross-sectional configuration of a conventional intercept valve. FIG. 9A is a diagram showing a state in which foreign particles are deposited on the upper portion of the bush back sheet, and FIG. 9B is a diagram showing a state in which foreign particles are deposited on the outer peripheral surface of the valve stem back sheet. FIG. 9C is a view showing a state where foreign particles are sandwiched between the valve stem backsheet and the bush backsheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generator 2 Turbine shaft 3 High pressure steam turbine 4 Medium pressure steam turbine 5 Low pressure steam turbine 6 Boiler 7 Reheater 8 Condenser 9 Main steam stop valve 10 Steam control valve 11 Reheat steam stop valve 12 Intercept valve 13 Control Machine 14 emergency governor 15 valve casing 16 disc 17 arm 18 bearing flange 19 support shaft 20 connecting piece 21 valve stem 22 valve stem bushing 23 valve stem guide piece 24 oil cylinder 25 valve bottom lid 26 valve casing 27 strainer 28 intercept sub valve 29 intercept main valve 30 valve stem 31 valve stem bush 32 valve stem guide piece 33 oil cylinder 34 valve bottom cover 35 balance chamber 36 seal ring 37 valve canopy 38 balance chamber sleeve 39 valve seat 40 passage 41 inlet 42 inlet 43 outlet 44 valve Rod back seat 45 Bush back seat 50 Steam valve 51 Valve casing 51a Opening 52 Enter Port 53 Outlet 54 Lid 54a Through part 55 Valve seat 56 Valve body 57 Main valve 58 Sub valve 59 Balance chamber 60 Passage 61 Bolt 62 Convex 63 Valve rod 64 First valve rod drive mechanism 65 Cover side bush 66 Valve rod bush 67 Gear Portion 68 Gear 69 Valve stem bushing mechanism 70 First torque measuring means 71 Rack portion 72 Pinion 73 Valve rod 74 Valve rod bushing 75 Gear portion 76 Gear 77 Second valve rod driving mechanism 78 Second torque measuring means 79 Valve rod 80 Valve Bar bush

Claims (9)

In steam valves used in steam turbine plants,
A valve casing including a steam inlet and a steam outlet;
A lid that closes an opening provided on one surface of the valve casing;
A valve seat provided in the valve casing;
A valve body provided in the valve casing and freely contactable with the valve seat;
A valve stem connected to the valve body, penetrating the lid and provided movably with respect to the lid;
A first valve stem drive mechanism coupled to the valve stem and driving the valve stem in the axial direction;
A lid-side bush fixed to the penetrating portion of the lid through which the valve stem penetrates;
A valve stem bush interposed between the lid side bush and the valve stem and provided movably with respect to the lid side bush;
A steam valve, comprising: a valve stem bush drive mechanism coupled to the valve stem bush and driving the valve stem bush.   The steam valve according to claim 1, wherein the valve stem bush is movable in a circumferential direction with respect to the lid-side bush.   The steam valve according to claim 1, wherein the valve stem bush is movable in the axial direction of the valve stem with respect to the lid-side bush.   The steam valve according to any one of claims 1 to 3, wherein the valve rod bush drive mechanism is one of a steam pressure drive type, an electric drive type, and a hydraulic drive type.   A first torque measuring means is provided between the valve stem bush and the valve stem bush driving mechanism, and the driving force of the valve stem bush driving mechanism is variable according to the torque value measured by the first torque measuring means. The steam valve according to any one of claims 1 to 4, wherein: In steam valves used in steam turbine plants,
A valve casing including a steam inlet and a steam outlet;
A lid that closes an opening provided on one surface of the valve casing;
A valve seat provided in the valve casing;
A valve body provided in the valve casing and freely contactable with the valve seat;
A valve stem connected to the valve body, penetrating the lid and provided movably with respect to the lid;
A first valve stem drive mechanism coupled to the valve stem and driving the valve stem in the axial direction;
A valve stem bush fixed to the penetrating portion of the lid through which the valve stem penetrates,
The valve stem is rotatable about a central axis, and a second valve stem drive mechanism that rotationally drives the valve stem is further connected to the valve stem ,
Torque measuring means is provided between the valve stem and the second valve stem driving mechanism, and the driving force of the second valve stem driving mechanism is variable according to the torque value measured by the torque measuring means. A steam valve characterized by.   The steam valve according to claim 6, wherein the second valve rod drive mechanism is one of a steam pressure drive type, an electric drive type, and a hydraulic drive type.   The steam valve according to any one of claims 1 to 6, wherein an uneven shape is formed on an outer peripheral surface of the valve stem.   The steam valve according to claim 1, wherein an uneven shape is formed on an inner peripheral surface of the valve stem bush.

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