JP4537912B2 - Steam turbine plant with high temperature steam valve and high temperature steam valve - Google Patents

Description

  The present invention relates to a high temperature steam valve applied to a high temperature steam turbine system, and more particularly to a high temperature steam valve employing a cooling structure for cooling valve components and a steam turbine plant including the high temperature steam valve.

  In recent years, thermal power plants for commercial use have been demanded to further improve the efficiency of steam turbines from the viewpoint of environmental problems, and as a result, the steam temperature tends to increase more and more. Currently, the steam conditions widely adopted are 169 Kg / cm 2 × 566 ° C. or 246 Kg / cm 2 × 566 ° C., and the current highest steam condition is 610 ° C. The reason why these steam conditions are adopted is largely due to the cost constraints of the materials used for the construction of each member of the steam valve provided to control the steam flow rate of the steam turbine. .

  As is well known, a steam valve is configured such that a valve body disposed opposite to a valve seat in a valve casing is driven from the outside by a valve stem, and this valve stem is inserted through a bush at a valve stem penetration portion of the valve casing. A small gap is provided between the bush and the valve stem to allow sliding. In the unit that adopts the highest steam condition with a steam temperature of 610 ° C, the material constituting each member of the steam valve is a heat-resistant alloy steel such as 12Cr steel for the valve casing, nitrided steel for the bush, and 12Cr for the valve stem. Each adopts steel.

  By the way, the current trend is to save energy and to increase the steam temperature. For this reason, adoption of steam temperatures exceeding 610 ° C, which is the highest steam temperature at present, of 650 ° C or even 700 ° C or higher is under consideration. Although higher steam temperatures are welcomed to improve the thermal efficiency of steam turbine systems, they are extremely harsh for the components of steam valves and under high steam temperatures, the valve stems creep. In addition, the oxide scale may adhere to and accumulate on the sliding portion between the valve stem and the bush, and smooth sliding may be hindered, and the sliding portion between the valve stem and the bush may be fixed.

For this reason, in the conventional high-temperature steam valve, an invention is made such that a hole is machined in the valve stem and cooling steam is allowed to flow through the hole to cool the valve stem (for example, Patent Document 1), or the valve lid of the valve casing is an upper lid. In addition to cooling the casing flange by flowing cooling steam between the top lid and the inner lid, an oxidation-resistant layer is provided on the sliding part of the valve stem and bush to attach the oxide scale. In the invention that prevents accumulation (for example, Patent Documents 2 and 3), and a butterfly valve that adjusts the opening degree of the flow path by rotating the disc-shaped valve body, a valve shaft cylinder through which one end of the valve rod penetrates ( A cylindrical jacket is additionally provided on the outer periphery of the outer periphery of a gland packing or a shaft seal portion made of an elastic cushioning material or the like via a space portion, and a cooling medium is externally provided in the annular space portion. (For example, Patent Document 4) is disclosed It has been.
Japanese Utility Model Publication No. 57-145879 Japanese Utility Model Publication No. 61-14276 JP-A-8-93407 JP 2004-19784 A

  However, in the invention described in Patent Document 1 above, only the valve stem can be cooled, but cooling of the sliding portion between the valve stem and the bush is not taken into consideration. It is not enough as a measure to prevent adhesion accumulation. Further, in the inventions described in Patent Documents 2 and 3, although the bolt for tightening the flange portion of the valve casing and the valve lid can be cooled, the sliding portion between the valve stem and the bush cannot be cooled as in Patent Document 1. As a result, in the inventions described in Patent Documents 2 and 3, even when an oxidation-resistant layer is provided for higher-temperature steam, it is impossible to prevent adhesion and deposition of oxide scale.

Furthermore, in the invention described in Patent Document 4, since the shaft sealing portion is cooled rather than the bearing member that rotatably supports the valve rod, the bearing member, that is, the valve rod is passed through the valve rod from the inside of the valve. Heat is transferred to the sliding portion, and the valve stem sliding portion cannot be sufficiently cooled. Therefore, the invention described in Patent Document 4 is not sufficient as a measure for preventing the deposition and deposition of oxide scale on the valve stem sliding portion that supports the rotation of the valve stem.
As described above, in the techniques described in Patent Documents 1 to 4, since the oxide scale adheres to and accumulates on the valve stem sliding portion, the wear amount of the valve stem sliding portion increases, and the sliding between the bush and the valve stem increases. The moving gap is not maintained properly for a long time, so it must be replaced.

  Accordingly, the present invention has been made in view of the above-mentioned drawbacks of the prior art. The sliding portion between the valve stem and the bush provided in the valve stem penetrating portion of the valve casing is appropriately cooled, and the oxidized scale is formed on the sliding portion. It is intended to provide a high-temperature steam valve and a steam turbine plant equipped with a high-temperature steam valve that can prevent the adhesion and deposition of the valve and keep the sliding gap between the valve stem and bushing properly for a long period of time. is there.

  In order to achieve the above object, a high-temperature steam valve according to claim 1 includes a main steam inlet, a valve casing having a main steam outlet and a valve chamber therein, a valve seat disposed in the valve chamber, and the valve seat. In a high-temperature steam valve having a valve body provided opposite to the valve body and a valve rod that slidably penetrates the valve casing and drives the valve body, the valve body is cooled so as to surround the valve rod penetration portion of the valve casing. A steam passage is provided, cooling steam is introduced into the cooling steam passage from the outside, and the cooling steam passing through the cooling steam passage is discharged toward the valve rod in the valve chamber.

According to the present invention, in a high-temperature steam valve having a steam temperature of 610 ° C. or higher, the wear resistance of the bush and the valve stem is increased, and galling or sticking hardly occurs, and the service life of both parts is increased.
Accordingly, it is possible to achieve remarkable effects such as contributing to improvement of product reliability and reducing repair costs or replacement costs.

Embodiments of the present invention will be described below with reference to the drawings.
Example 1
FIG. 1 is a sectional view of an embodiment in which the present invention is applied to a combined reheat high temperature steam valve.
In FIG. 1, first, the basic configuration of the combined reheat high temperature steam valve will be described. Reference numeral 1 denotes a composite reheat steam valve as a whole. Reference numeral 2 denotes a valve casing, and a main steam inlet 3 is provided on the left side of the figure, and a main steam outlet 4 is provided on the lower side of the right side, which is the opposite side, and between the main steam inlet 3 and the main steam outlet 4. The valve seat 6 is disposed in the valve chamber 5 formed in the first and second valve bodies 8 and 8 that are driven to move up and down from the upper and lower parts of the figure relative to the valve seat 6. Arranged freely. In addition, 9 is a cylindrical strainer which removes the dust in the main steam which flowed in.

  The first valve body 7 has a substantially H-shaped cross section and an outer peripheral surface formed in a cylindrical shape. One end of the valve stem 10 is attached to the upper surface of the center of the first valve body 7 in the drawing, and the inner peripheral surface of the guide portion 11 is the outer peripheral surface. It is configured to be guided so as to be slidable. The guide portion 11 is fixed concentrically with the bush 14 on the inner surface of the valve lid 12 of the valve casing 2, that is, on the valve chamber 5 side. An intermediate portion of the valve stem 10 is slidably supported by a bush 14 fitted in a valve stem penetrating portion 13 formed at the central portion of the valve lid 12 of the valve casing 2, and the other end portion is supported by the valve lid 12. Is connected to a first actuator 15 installed on the upper side of the first actuator 15. The first actuator 15 raises and lowers the first valve body 7 via the first valve rod 10 according to an external command, thereby controlling the flow rate of the main steam.

  By the way, the valve lid 12 has an appropriate number of steam vent holes 16 in the radial direction for extracting steam leaking from the gap between the bush 14 and the sliding portion of the first valve rod 10 in the radial direction (one is shown in the figure). A cooling steam passage 17 for cooling the bush 14 and the valve stem 10 is provided. The cooling steam passage 17 branches from a cooling steam manifold 18 provided in an annular shape so as to surround the bush 14, a cooling steam introduction hole 19 for supplying cooling steam to the cooling steam manifold 18, and the cooling steam manifold 18. And a plurality of cooling steam holes 20 provided in the axial direction of the bush 14 and a cooling steam discharge hole 21 for communicating the cooling steam holes 20 with the valve chamber 5.

  On the other hand, the lower surface of the second valve body 8 in the center is fixed to one end of the second valve rod 22. An intermediate portion of the second valve rod 22 is provided by a bush 25 fitted to a valve rod penetrating portion 24 formed at the center of a cylindrical guide portion 23 provided so as to rise from the lower opening of the valve casing 2. The other end is connected to a second actuator 26 installed at the lower part of the valve casing 1.

By the way, the guide portion 23 has an appropriate number of steam vent holes 27 in the radial direction for extracting steam leaking from the gap between the sliding portions of the bush 25 and the second valve rod 22 in the radial direction (one is shown in the figure). And a cooling steam passage 28 for cooling the bush 25 and the valve stem 22 is provided. The cooling steam passage 28 includes an annular cooling steam manifold 29 that surrounds the bush 25, a cooling steam introduction hole 30 that supplies the cooling steam to the cooling steam manifold 29, and the cooling steam manifold 29 to the bush 25. The cooling steam holes 31 are provided in the direction of the axis of the cooling steam, and the cooling steam discharge holes 32 through which the steam that has finished heat exchange through the cooling steam holes 31 are communicated with the valve chamber 5.
The 2nd actuator 26 raises / lowers the 2nd valve body 8 via the 2nd valve rod 22 by the command from the outside, and controls interruption | blocking and outflow of a vapor | steam.

  In the composite reheat steam valve configured as described above, when the valves are fully closed, the tip surfaces of the first valve body 7 and the second valve body 8 abut against the valve seat 6, and the main steam inlet of the valve casing 2 3, the flow of main steam of 610 ° C. or more entering the valve chamber 5 inside the valve casing 2 is blocked at the contact portion between the first valve body 7, the second valve body 8 and the valve seat 6, and the main steam outlet 4 Does not flow through.

  In this state, the valve stop function is opened by moving the second valve body 8 upward by the second valve rod 22. Further, by moving the first valve body 7 upward by the first valve rod 10, the control valve function is opened and main steam is formed between the first valve body 7, the second valve body 8 and the valve seat 6. It is discharged from the main steam outlet 4 through the created gap.

  On the other hand, in the upper part of the valve casing 1, the cooling steam of less than 610 ° C. is supplied to the annular cooling steam manifold 18 from the cooling steam introduction hole 19 provided in the valve lid 12 of the valve casing 2. This cooling steam is diverted from the cooling steam manifold 18 to a plurality of cooling steam holes 20 arranged in the circumferential direction so as to surround the bush 14, thereby causing the bush 14 and the valve stem 10 to circumferentially pass through the valve lid 12. Cool almost uniformly in the direction. The cooling steam that has finished heat exchange with the valve lid 12 is then discharged toward the valve rod 10 inside the valve chamber 5 through the cooling steam discharge hole 21. The valve stem 10 is directly cooled by the discharged cooling steam. This cooling steam is then mixed with the main steam that has entered from the main steam inlet 3, passes through the gap between the valve body and the valve seat, and is finally discharged from the main steam outlet 4.

Similarly, also in the lower part of the valve casing 2, the cooling steam is supplied to the annular cooling steam manifold 29 from the cooling steam introduction hole 30 provided over the lower part of the valve casing 2 and the cylindrical guide part 23. The cooling steam is diverted from the cooling steam manifold 29 to a plurality of cooling steam holes 31 arranged in the circumferential direction so as to surround the bush 25, thereby causing the bush 25 and the valve rod 22 to circumferentially pass through the guide portion 23. Cool almost uniformly in the direction.
The cooling steam that has finished heat exchange with the guide portion 23 is then discharged toward the valve rod 22 inside the valve chamber 5 through the cooling steam discharge hole 32. The valve stem 22 is directly cooled by the discharged cooling steam. The cooling steam is then mixed with the main steam that has passed through the gap between the valve body 8 and the valve seat 6, and is finally discharged from the main steam outlet 4.

  In this way, the cooling steam is mixed with the main steam and discharged from the combined reheat high-temperature steam valve 1 and introduced into a steam turbine (not shown). The amount of cooling steam is larger than the amount of main steam. Since it is so small, it does not affect the steam introduced into the steam turbine.

As described above, according to this embodiment, the cooling steam introduction holes 19 and 30, the cooling steam manifolds 18 and 29, and the cooling steam holes 20 and 31 provided in the valve lid 12 and the guide portion 23 of the valve casing 2 are provided. By configuring the cooling steam to flow at a temperature lower than 610 ° C., the valve stem penetrating portion can be effectively cooled to an appropriate temperature. Furthermore, since the valve rods 10 and 22 in the valve chamber 5 are directly cooled by the cooling steam discharged into the valve chamber 5 through the cooling steam discharge holes 21 and 32, respectively, the amount of heat reaching the sliding portion can be reduced.
As a result, the sliding portion between the bush 14 and the valve stem 10 and the sliding portion between the bush 25 and the valve stem 22 can be maintained at a temperature of less than 610 ° C., thereby preventing oxide scale from being deposited on the sliding portion. Even if a conventionally used material such as a nitriding material is used for the sliding portions of the valve stem 10, the bush 14, the bush 25, and the valve stem 22, it can be used for a long time.

(Example 2)
A second embodiment of the present invention will be described with reference to FIGS. As in the first embodiment, this embodiment is also applied to a combined reheat high temperature steam valve, and the same reference numerals are given to the portions corresponding to those in FIG.

  In FIG. 2, the main feature of the second embodiment is that piston rings 33 and 34 are arranged on both sides so as to sandwich the openings of the steam vent holes 16 and 27 facing the outer periphery of the valve rods 10 and 22. Further, the bushes 14 and 25 are divided into a plurality of parts in the circumferential direction, and other configurations are the same as those in FIG.

  In the case of the second embodiment, the bush 14 is embedded from the inside of the valve to the substantially middle part in the thickness direction of the valve lid 12 without penetrating the valve lid 12, and the valve rod 10 positioned outside the piston ring 33. The gap between the valve lid 12 and the through hole is set to be slightly larger than that in the first embodiment shown in FIG. A pair of annular grooves are provided in the valve lid 12 so as to sandwich the opening of the steam vent hole 16 facing the outer periphery of the valve stem 10, and the piston ring 33 is accommodated in these grooves. By fitting the rod 10, steam does not escape from the gap between the valve rod 10 and the through hole of the valve lid 12. As shown in FIG. 4, the piston ring 33 is formed by bending a single flat bar having step portions with different directions at both ends into an annular shape, and overlapping the step portions at both ends. By providing a gap 332 next to the overlapping portion 331, a spring effect is provided.

  On the other hand, the lower end portion of the bush 25 does not penetrate the guide portion 23 as shown in FIG. 1 but is embedded up to the length before the steam vent hole 127, and the valve rod 22 penetrating the guide portion 23 and the guide portion 23 penetrate. The gap with the hole is also set slightly larger than in the case of FIG. An annular groove is provided in the valve casing 2 so as to sandwich the opening of the steam vent hole 27 facing the outer periphery of the valve rod 22, and the piston ring 34 is accommodated in the groove, and the valve rod 22 is inserted into the piston ring 34. By fitting, steam does not escape from the gap between the valve stem 22 and the through hole of the guide portion 23. The piston ring 34 is formed in the same manner as the piston ring 33.

  As a result of adopting such a configuration, the composite reheat high temperature steam valve according to the second embodiment has a large gap between the bush 14 and the valve stem 10 and between the bush 25 and the valve stem 22, which facilitates sliding. . When the gap becomes larger, the cooling steam that has exited from the cooling steam holes 20 and 31 is likely to leak in the direction of the steam vent holes 16 and 27, but the flow is blocked by the piston rings 33 and 34, so that the leakage can be stopped. The piston rings 33, 34 have a spring effect due to the action of the overlapping portion 41 and the gap 42, and even if the valve stems 10, 22 expand and contract due to heat, the valve stems 10, 22 and the piston rings 33, 34 Since the gap can be almost eliminated, leakage can be stopped.

  Further, as shown in FIG. 5, the bushes 14 and 25 have a divided portion 141 in the circumferential direction, and the bushes 14 and 25 are thermally deformed or a temperature difference is generated between the valve rods 10 and 22. Even when the gap becomes narrow, it is configured so that no galling or sticking occurs.

  Therefore, the combined reheat high temperature steam valve of the second embodiment can be used for a long period of time, exhibits high slidability and a high leakage prevention function, and further, galling and sticking that can arise from thermal deformation due to cooling. Can also be prevented.

(Example 3)
A third embodiment of the present invention will be described with reference to FIGS. 3, 4, and 5. FIG. This embodiment shows an example applied to a main steam stop valve.
3, since the main steam stop valve 100 of the third embodiment has one valve body, the valve lid 12 is not provided with the valve rod penetrating portion 13 as shown in FIG. A rod penetrating portion 24 is provided. The valve casing 2 of the present embodiment is provided with a main steam inlet 3 on the left side in the figure, and a main steam outlet 4 on the opposite lower side in the figure, and between the main steam inlet part 3 and the main steam outlet part 4. A valve seat 6 and a valve body 8 driven from the lower part of the figure with respect to the valve seat 6 are disposed in the valve chamber 5 in the vertical position formed in the figure. The shutoff and outflow of the main steam are adjusted by the movement of the valve body 8 with respect to the valve seat 6.

In the third embodiment, as in the second embodiment, the valve rod 22 has one end connected to the center of the lower end of the valve body 8 and the other end slidably passed through the cylindrical bush 25. Thus, the actuator 26 is connected. The actuator 26 moves the valve body 8 up and down via the valve rod 22 according to a command from the outside, and adjusts the cutoff and outflow of the main steam.
In addition, since the cooling structure of the valve stem penetrating portion and the structure for preventing vapor leakage from the valve stem penetrating portion in the present embodiment are substantially the same as those in the second embodiment described above, description thereof will be omitted.

  The high-temperature main steam stop valve 100 of the third embodiment can be used for a long period of time, exhibits high slidability and a high leakage prevention function, and also has galling and sticking that can occur from thermal deformation due to cooling. To prevent.

  Furthermore, in order to improve the slidability, the clearance between the bush 25 and the valve stem 22 is made slightly larger than before, and a piston ring 34 for preventing leakage is provided before and after steam removal in order to prevent an increase in the leakage of cooling steam. By arranging it, it can be used for a long time, and also exhibits high slidability and high leakage prevention function. Further, by adopting a structure in which the bush 25 is vertically divided, it is possible to prevent galling and sticking that may occur due to thermal deformation due to cooling.

  In addition, although the above Example described the case where it applies to a composite type reheat steam valve and a main steam stop valve, this invention is not limited to this, The main steam control applied to a high temperature steam system The present invention can also be applied to steam valves such as valves, reheat steam stop valves, and reheat steam control valves.

Sectional drawing for demonstrating Example 1 of this invention. Sectional drawing explaining Example 2 of this invention. Sectional drawing explaining Example 3 of this invention. The perspective view of the piston ring employ | adopted as Example 1,2. The perspective view of the split type bush employ | adopted as Example 1,2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Valve casing, 3 ... Main steam inlet, 4 ... Main steam outlet, 5 ... Valve chamber, 6 ... Valve seat, 7 ... Valve body, 8 ... Valve body, 9 ... Strainer, 10 ... Valve rod, 11 ... Guide part , 12 ... Valve lid, 13 ... Valve rod penetration, 14 ... Bush, 15 ... Actuator, 16 ... Steam vent, 17 ... Cooling steam passage, 18 ... Cooling steam manifold, 19 ... Cooling steam inlet, 20 ... Cooling steam Hole: 21 ... Cooling steam discharge hole, 22 ... Valve rod, 23 ... Guide part, 24 ... Valve rod penetrating part, 25 ... Bush, 26 ... Actuator, 27 ... Vapor vent hole, 28 ... Cooling steam passage, 29 ... Cooling steam Manifold, 30 ... cooling steam introduction hole, 31 ... cooling steam hole, 32 ... cooling steam discharge hole, 33 ... piston ring, 34 ... piston ring, 331 ... overlapping part, 332 ... gap, 141 ... divided part.

Claims (7)

A main steam inlet, a main steam outlet and a valve casing having a valve chamber therein, a valve seat disposed in the valve chamber, a valve body provided opposite to the valve seat, and slidably penetrating the valve casing In a high temperature steam valve provided with a valve rod for driving the valve body,
A cooling steam passage is provided so as to surround the valve rod penetration part of the valve casing, cooling steam is introduced into the cooling steam passage from the outside, and the cooling steam passing through the cooling steam passage is discharged toward the valve rod in the valve chamber. A high temperature steam valve characterized by being configured to do so.   The high-temperature steam valve according to claim 1, wherein a bush for smooth sliding of the valve shaft is fitted in a valve rod penetrating portion of the valve casing.   The cooling steam passage is branched from the cooling steam manifold, a cooling steam introduction hole for introducing cooling steam from the outside, a cooling steam manifold formed so as to communicate with the cooling steam introduction hole and surround the valve rod penetrating portion, and 2. The cooling steam hole formed in parallel with the valve stem penetrating portion and the cooling steam discharge hole for discharging the steam having finished heat exchange in the cooling steam hole into the valve chamber. High temperature steam valve.   2. The high temperature steam valve according to claim 1, wherein a steam vent hole is provided in the valve rod penetrating portion, and a piston ring for preventing steam leakage is disposed before and after the opening facing the valve shaft of the steam vent hole.   The high-temperature steam valve according to claim 2, wherein the bush is divided into a plurality of parts in the circumferential direction.   The high temperature steam valve according to any one of claims 1 to 5, wherein the main steam temperature is 610 ° C or higher and the cooling steam temperature is lower than 610 ° C. The steam turbine plant provided with the high temperature steam valve in any one of Claims 1 thru | or 6.

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