JP5944240B2 - Steam valve device and power generation equipment - Google Patents

Description

  Embodiments described herein relate generally to a steam valve device and a power generation facility.

  Normally, a steam control valve for sending steam to the steam turbine is used in a power generation facility including the steam turbine. In the steam control valve, a valve rod inserted into a cylindrical bush reciprocates on the inner surface of the bush.

  By the way, the gap between the bush and the valve stem should be as small as possible so that steam does not leak outside. However, if the gap is made too small, the valve stem itself may not move due to the effects of thermal expansion of the valve stem and adhesion of oxides when the steam control valve is operated.

JP 2010-159829 A

  In recent years, steam pressure and steam temperature conditions have risen to improve the performance of power generation facilities, and the external changes such as thermal expansion and oxide adhesion of the reciprocating valve stem when the steam control valve operates. The gap design size between the bush and the valve stem must be increased, and as a result, the amount of steam leakage tends to increase.

  Problems to be solved by the present invention are a steam valve device and a power generation facility that are resistant to thermal expansion and oxide adhesion, can reduce the amount of leaked steam, and can further improve the efficiency of the steam turbine and the power generation facility as a whole Is to provide.

The steam valve device of the embodiment includes a valve stem, a valve body, a valve stem support portion, and a seal portion. A valve body is provided at the tip of the valve stem. The valve body includes a steam inlet, an outlet through which steam flowing in from the inlet flows out, and an opening provided to face the outlet. The valve body opens and closes the outlet by the valve body by the axial movement of the valve stem inserted through the opening. The valve stem support portion is provided above the opening of the valve body so as to surround the valve stem. The valve stem support portion supports the valve stem moving in the axial direction. The seal portion is fixed to the valve stem support portion at the position of the opening of the valve body. The seal portion has an annular inner edge portion through which the valve rod passes. The seal portion includes a material whose inner edge portion is softer than an oxide attached to the valve stem.

It is a figure which shows the structure of the power generation equipment of 1st Embodiment. It is sectional drawing which shows the structure of a steam control valve. It is an enlarged view of the part of the code | symbol A of FIG. It is a figure which shows an example of a sealing member. It is a figure which shows the modification of a sealing member. It is a figure which shows the modification of a sealing member. It is a figure which shows the structure of 3rd Embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration of the power generation facility according to the first embodiment.
As shown in FIG. 1, the power generation equipment of the first embodiment includes a boiler 700, a main steam stop valve 701, a steam control valve 702 as a steam valve device, a high pressure turbine 710, a check valve 707, and a reheat steam stop valve. 703, an intercept valve 704, an intermediate pressure turbine 711, a low pressure turbine 712, a condenser 713, a feed water pump 714, and the like.

  In this power generation facility, the steam from the boiler 700 passes through the main steam stop valve 701 and the steam control valve 702, works on the high-pressure turbine 710, and then returns to the boiler 700 reheater via the check valve 707. And then flows into the intermediate pressure turbine 711 and the low pressure turbine 712 through the reheat steam stop valve 703 and the intercept valve 704 to work.

  The steam that flows out from the low-pressure turbine 712 is returned to water by the condenser 713, and is pressurized by the feed water pump 714 to be supplied to the boiler 700 again.

  Further, in this power generation facility, in order to increase the operation efficiency of the plant, the high-pressure turbine bypass valve 705 and the boiler 700 provided in the flow path connecting the inflow side of the main steam stop valve 701 and the inflow side of the reheater of the boiler 700 are used. A low-pressure turbine bypass valve 706 is installed in the flow path connected between the outflow side of the reheater and the condenser 713 so that the boiler system can be circulated independently of the operation of the turbine. ing.

  As shown in FIG. 2, the steam control valve 702 used in the front stage of the high-pressure turbine 710 includes a steam valve main body 200, a bush 201, an upper cover 202, a valve seat 203 as a steam outlet, a valve body 204, and a valve stem 205. , An opening 207 serving as a steam inlet, an opening 208 serving as a steam outlet, an opening 209 serving as an insertion port for the valve rod 205 and the valve body 204, and a seal member 301 serving as a seal portion.

  The steam valve main body 200 includes an opening 207 that is an inlet of steam, a valve seat 203 that is an outlet from which the steam that flows in from the opening 207 flows out, an opening 209 that is provided to face the valve seat 203, A steam chamber 210 which is a space provided in the center is provided.

  A valve seat 203 is provided in the steam chamber 210 of the steam valve main body 200. The valve seat 203 is provided with an opening 208 serving as a steam outlet. The opening 208 allows the steam to flow out from the steam valve main body 200.

  In the steam valve main body 200, the valve body 204 opens and closes the opening 208 (outlet) of the valve seat 203 by the axial movement of the valve rod 205 inserted into the steam chamber 210 through the opening 209.

  The upper lid 202 is fixed to the upper part of the opening 209 of the steam valve main body 200 and closes the upper surface of the steam valve main body 200. The upper lid 202 is provided with a through-hole penetrating in the vertical direction and continues to the opening 209. A hydraulic drive mechanism 206 is supported above the upper lid 202. A valve stem 205 is supported (connected) downward (vertically) by the hydraulic drive mechanism 206.

  The valve rod 205 is reciprocated up and down by a hydraulic drive mechanism 206. In the case of this example, since the through hole of the upper lid 202 becomes a sliding surface with the valve rod 205, a cylindrical bush 201 made of a metal resistant to friction is inserted into this portion.

  The bush 201 and the upper lid 202 are collectively referred to as a valve stem support portion. This valve stem support portion is provided above the opening 209 of the steam valve main body 200 so as to surround the valve stem 205. The valve stem support portion supports (guides) the valve stem 205 that moves in the axial direction so that it does not shake sideways.

  That is, the steam control valve 702 causes the steam from the boiler 700 to flow In into the steam chamber 210 through the opening 207, and the hydraulic drive mechanism 206 pulls up or presses the valve body 204 at the tip of the valve rod 205 (reciprocating operation). By doing so, the opening 208 of the valve seat 203 is opened and closed, and the outflow of steam from the steam chamber 210 is controlled.

  The valve body 204 is provided so as to contact the valve seat 203 and open and close the opening of the valve seat 203. The valve body 204 is provided at the tip of a valve rod 205 inserted into the through hole of the upper lid 202 inside the steam valve main body 200.

  The seal member 301 is an annular member, and has an annular inner edge portion through which the valve rod 205 passes. The inner edge portion has at least a surface made of a material softer than an oxide adhering to the valve stem 205, such as an oxide scale. The seal member 301 is fixed to the valve stem support portion (upper lid 202) at the position of the opening 209 of the steam valve main body 200.

  In the steam control valve 702 having such a structure, when the valve rod 205 is driven in the vertical direction by the hydraulic drive mechanism 206, the valve body 204 contacts or separates from the valve seat 203 to open and close the steam flow path, By controlling the amount of steam flowing to the high pressure turbine 710, the rotational speed of the high pressure turbine 710 is controlled.

  In designing the portion of the valve stem 205 and the bush 201, the gap between the inner diameter of the bush 201 and the outer diameter of the valve stem 205, which is the sliding surface of the valve stem 205, is as follows. The reciprocation of the valve stem 205 is not obstructed in consideration of the difference in thermal expansion due to the combination of materials, the amount of oxide scale adhering to the valve stem 205 and the bush 201 expected from the scheduled operation period (the valve stem stick It is determined to the extent that it does not cause.

Here, the configuration in the vicinity of the valve stem 205, the bush 201 and the seal member 301 (portion A in FIG. 2) will be described in detail with reference to FIG.
The gap dimension between the outer diameter of the valve stem 205 and the inner diameter of the bush 201 inserted into the through hole of the upper lid 202 into which the valve stem 205 is inserted is assumed even when the steam valve main body 200 is heated further in the future. Keep the design dimensions so far.

  As shown in FIG. 3, the valve rod 205 is passed through an annular seal member 301, and bolts 302 are attached to the bottom surface of the upper lid 202 with the seal member 301 sandwiched between annular protective covers 303 a and 303 b disposed above and below the seal member 301. Secure with. The inner diameters of the protective covers 303 a and 303 b are larger (wider) than the inner diameter of the seal member 301.

  More specifically, the seal member is configured such that the outer surface of the valve stem 205 and the abradable coating layer 20 at the inner edge of the seal member 301 are brought close to each other and slid in a reciprocating motion (so that they rub against each other). 301 is attached to the bottom surface of the upper lid 202 with a plurality of bolts 302. Here, the approach is to make the distance (interval) between the outer diameter of the valve stem 205 and the inner diameter of the bush 201 equal or narrower (interval).

  As shown in FIG. 4, the seal member 301 is formed by applying an abradable coating to the annular (ring-shaped) base material 19 and the surface (at least the inner edge portion 304) of the base material 19. And a double coating layer 20 (a machinable gap forming film). The base material 19 is a hard metal. The material of the base material 19 shall be prescribed | regulated by the below-mentioned description.

  The inner edge portion 304 (abradable coating layer 20) of the seal member 301 is a portion (coating) that is preferentially cut when it comes into contact with an opposing component (valve stem 205).

  The seal member 301 in this example has a continuous annular shape (ring shape), and the inner diameter of the inner edge 304 facing the valve stem 205 is narrower than the gap between the valve stem 205 and the bush 201, and the valve stem It is comprised so that it may always contact without a gap between 205.

  For this reason, the seal member 301 smoothly cuts the abradable coating layer 20 of the seal member 301 when the oxide scale attached to the outer surface of the valve stem 205 passes through the reciprocating motion of the valve stem 205 ( The corner (top) of the abradable coating layer 20 is chamfered so as to be curved. In FIG. 4, a curved surface portion is indicated by a symbol r.

Here, the operation of the steam control valve 702 in the power generation facility of this embodiment will be described.
In the case of this embodiment, when the oxide scale adheres to the outer surface of the valve stem 205, the surface of the inner edge 304 of the seal member 301 on which the abradable coating layer 20 is formed is cut only in the portion where the oxide scale is attached. At the same time, it contacts the valve stem 205, and other portions are not cut while remaining in contact with the valve stem 205.

  This is because the inner surface of the seal member 301 is cut by the oxidized scale attached to the valve stem 205 as the operation time elapses, but even if the oxidized scale is attached, the valve stem 205 and the seal member 301 Means to always create a new contact state, and as a result, the gap between the valve stem 205 and the seal member 301 can be kept to a minimum, so that high steam sealability can be achieved. The inner surface of the seal member 301 does not hinder (restrain) the reciprocation of the valve stem 205.

  The thickness of the abradable coating layer 20 is an allowable cutting thickness, and is preferably about half the diameter difference between the valve stem 205 and the bush 201.

Next, a modification of the seal member 301 will be described with reference to FIG.
As shown in FIG. 5, the seal member 301 in this example is a continuous ring-shaped body (ring-shaped member), and the groove-like pocket 21 is provided in the inner edge portion 304.

  In this case, the chips of the abradable coating layer 20 on the inner surface of the cut seal member 301 enter the gap between the valve stem 205 and the bush 201 because the material of the abradable coating layer 20 itself is softer than the oxide scale. However, the reciprocation of the valve stem 205 is not obstructed (restrained), but the contact with the abradable coating layer 20 is formed in order to temporarily store the chips that have entered the gap when the amount of chips is large. Groove-shaped pockets 21 are processed in the axial direction of the surface.

  The groove-like pocket 21 may be provided in a plurality of stages according to the axial length of the contact surface, and in some cases, a small amount of the peeled oxide scale can be temporarily stored. It can be removed by cleaning at the opportunity to pause and disassemble.

  Further, the groove-like pocket 21 is further developed to provide a plurality of slits 22 at the inner edge of the seal member 301 as shown in FIG. By inserting a plurality of slits 22 into the inner edge of the seal member 301, the seal member 301 is divided in the axial direction, and the seal member 301 is configured by collecting a plurality of these pieces as a thin plate. can do.

  When the portion that slides with the valve stem 205 (inner edge portion 304 of the seal member 301) becomes a thin plate, the portion itself becomes an elastic body and elastic while contacting the oxide scale attached to the outer surface of the valve stem 205. Due to the deformation, a pressing force to the valve stem 205 can be further obtained, so that a high steam sealability can be obtained.

  A plurality of slits are formed in the sealing member 301 having the plurality of stages of slits 22 shown in FIG. By dividing vertically and horizontally, the elasticity of the seal member 301 is further increased, and it is easy to be elastically deformed while being in contact with the oxide scale attached to the outer surface of the valve stem 205, so that a strong pressing force against the valve stem 205 is obtained. Since it is obtained, it is needless to say that an even higher vapor sealability can be achieved.

  Here, the abradable coating layer 20, the means for forming the abradable coating layer 20, and the formation thereof are made possible so that the effect of the steam control valve 702 configured as described above can be maximized. The material of the base material (base material) of the seal member 301 is defined.

  The material of the seal member 301 is the same as that of the valve stem 205 so that the gap between the inner diameter of the seal member 301 and the outer diameter of the valve stem 205 is not changed. Preferably, the valve stem 205 has a high temperature exceeding 600 ° C. Select metals such as nickel-based and cobalt-based heat-resistant alloys called INCONEL and INCOLOY that are suitable for temperature steam. The metal material applied to the base material of the seal member 301 is most preferably the same material as the valve stem 205.

  In addition, the abradable coating layer 20 is an example of a material suitable for high temperature steam exceeding 600 ° C., the main component of which is Ni—Cr—Al—BN, aluminum oxide, zirconium oxide, silicon oxide, titanium oxide. In addition, an oxide ceramic containing at least one of magnesium oxide and beryllium oxide and a free-cutting metal excellent in heat resistance are desirable, but the present invention is not limited to this, and the above temperature condition is satisfied rather than an oxide scale. Any soft material can be used.

  Further, as a forming means for forming the abradable coating layer 20 as a film on the inner edge 304 of the seal member 301, there is a spraying method or a spraying technique in which the abradable material is heated and collided at a high speed in the form of molten fine particles. A cold spray method, electrical discharge machining method, sintering, build-up welding, plating method, and the like are desirable, but needless to say, various applications can be made without departing from the gist of the present invention.

  As described above, according to the first embodiment, the abradable coating layer 20 is formed on the inner edge portion 304 of the annular (ring-shaped) seal member 301, so that the valve rod 205 is removed as the operation time elapses. Since the abradable coating layer 20 is cut by the oxide scale that adheres to the surface and grows, and a new contact surface is always created, the valve stem 205 and the seal member 301 always come into close contact with each other. In addition, the gap between the valve stem 205 and the seal member 301 is always kept in contact (adherence), and high steam sealability can be achieved.

  For this reason, it is possible to drastically reduce the steam leaking from the gap between the bush 201 and the valve stem 205, which can greatly contribute to improving the efficiency of the steam turbine.

  Further, since the seal member 301 has a structure that fits into the position of the opening 209 in the upper part of the steam valve main body 200, the existing steam valve device can be easily added to the existing power generation equipment because it is easy to add the seal member 301. Thus, the efficiency of the steam turbine can be improved, and the efficiency of the entire power generation facility can be further improved.

(Second Embodiment)
Next, the second embodiment will be described. In the first embodiment, since the abradable coating layer 20 is cut by an oxide scale that grows by adhering to the outer surface of the valve stem 205 as the operation time elapses, the valve stem 205 and the seal member 301 are always Although the abradable coating layer 20 is expected to act in close contact with each other, the life of the abradable coating layer 20 depends on the amount of oxide scale produced, so that the oxidation adhered to the outer surface of the valve stem 205 as much as possible. It is desirable to suppress the amount of scale generated.

  Normally, the steam valve device is used under severe steam conditions under high temperature and high pressure, and further plays a role in controlling high-speed steam flow. At high temperatures, the metal surface becomes activated, It has a mechanism that reacts with high-temperature steam to generate an oxide scale by itself.

  The amount of oxide scale produced depends on the composition of the base material of the valve stem 205 and the atmospheric conditions, and it is used for a long period of time as the operating conditions increase and the periodic inspection cycle is extended, and it is formed under the operating conditions of high-temperature and high-pressure steam. Due to the low protection due to the non-uniformity of oxidized scale, the oxide scale thickness increases, so it is not easy to suppress the amount of oxide scale produced.

  As a result of a production test of oxide scale in a high-temperature atmosphere using materials used for steam valve devices, the results are: [Cobalt-based hard alloy <nickel 30-50% nickel-based alloy <12% Cr steel <low alloy steel] It was found that the generation amount of oxide scale increased in order.

  In the case of a nickel-based alloy of 30 to 50% nickel, the amount of oxide scale produced is larger than that of a cobalt-based hard alloy called Stellite (trade name) or the like, but the rate of increase with time is relatively small, 12% As for Cr steel and low alloy steel, it was revealed that the amount of oxide scale produced was larger and the rate of increase with time was larger.

  The amount of oxide scale produced depends on the amount of Cr contained in the steel, and by increasing the Cr content, a dense Cr monolayer oxide consisting of a protective oxide film (eg, Cr2O3 is preferred) in a high temperature steam environment. This is because the film is stably generated.

  Accordingly, a cobalt-based hard alloy having a Cr content of approximately 30% by weight corresponds to this, and the amount of oxide scale generated is very small compared to other materials.

  In the main steam valve device, the cobalt base hard alloy is used for the valve seat portion in which the valve body 204 abuts against the valve seat 203 to block the steam, and even in the actual product, the valve seat portion and its surrounding members are used. The difference in the attached amount of oxide scale is recognized.

  Therefore, the second embodiment is configured by combining the abradable coating layer 20 and the valve stem 205 having a cobalt base hard alloy with a small amount of oxide scale generated on the outer surface.

  Since the outer surface of the valve stem 205 becomes a slidable contact surface with the abradable coating layer 20, the surface texture (surface roughness) is preferably finer than Rz1.6 (ISO standard compliant), and the surface texture is fine. Further, the adhesion of oxide scale can be suppressed.

  According to the second embodiment, an effect of reducing the amount of the abradable coating layer 20 cut by the oxide scale can be obtained, and the life of the steam control valve 702 can be extended.

  The valve stem 205 is made of a nickel-base alloy that has a larger amount of oxide scale than the cobalt-base hard alloy and the outer surface is nitrided, or a nickel-base alloy as described above. Any of the valve stems 205 provided with a dense Cr single layer oxide film (for example, Cr2O3) made of an oxide of a component element of the base material on the outer surface, and a combination of materials on the sliding contact surface of the abradable coating layer 20 However, these are one of effective means for obtaining the effects of this embodiment, although the life is slightly shorter than the valve stem 205 provided with the aforementioned cobalt base hard alloy on the outer surface. Needless to do.

(Third embodiment)
FIG. 7 is a cross-sectional view showing a main part of the third embodiment of the steam valve device according to the present invention. The same components as those in FIG. To do.

  In the steam control valve 702 described above, since the gap between the outer diameter of the valve rod 205 penetrating the upper lid 202 and the inner diameter of the bush 201 provided in the penetrating portion of the upper lid 202 of the valve rod 205 is as large as the current state, When the rod 205 reciprocates, the valve rod 205 may swing in a direction orthogonal to its axial direction.

  In contrast, in the configuration of the first embodiment described above, the inner surface of the seal member 301 is assembled so as to be in contact with the valve stem 205 and is fixed to the upper lid 202. Unable to follow the moving movement.

  Therefore, in the third embodiment, as shown in FIG. 7, the seal portion main body is slidable in the direction orthogonal to the reciprocating direction of the valve stem 205 and the annular block 402 is in contact with the outer surface of the valve stem 205. The fixed block 403 is provided, and the hollow disk-shaped protective covers 303a are arranged on both outer surfaces of the fixed block 403 so that the fixed block 403 and the annular block 402 are integrally attached to the upper lid 202 with bolts 302. I made it.

  That is, in the first embodiment, the seal portion is configured by one member (the seal member 301). However, in the third embodiment, the seal portion 401 is loosely fitted to the shaft of the valve stem 205. And a fixed block 403 that is fixed to the valve stem support portion and slidably supports the annular block 402 in a direction orthogonal to the axis of the valve stem 205.

  An abradable coating layer 20 (a machinable gap forming film) is formed on the annular inner edge 304 of the annular block 402 as in the first embodiment.

  In the case of this third embodiment, the inner diameter of the protective cover 303a is set to be larger than the inner diameter of the bush 201, so that it does not contact the valve stem 205.

  Therefore, with the configuration as in the third embodiment, in addition to the effects of the first and second embodiments, the reciprocating direction (axial direction) of the valve stem 205 by the fixed block 403 and the protective cover 303a. Since the annular block 402 is held so as to be slidable (movable) in a direction orthogonal to the valve rod 205, the inner edge 304 of the seal member 401 contacts the valve rod 205 even if the valve rod 205 swings in a direction orthogonal to the reciprocating motion. In this state, the movement of the valve stem 205 can be followed.

  Since the annular block 402 is separate from the fixed block 403, the annular block 402 can be easily replaced during maintenance.

  Further, since the annular block 402 is protected by a protective cover 303a attached to the fixed block 403, the annular block 402 is prevented from being damaged by foreign matter even if foreign matter flows together with steam from the steam inlet of the steam valve body. it can.

  Note that the abradable coating layer 20 formed on the inner edge 304 of the annular block 402 in the above embodiment is a consumable part because it is a part cut by the oxide scale attached to the valve stem 205, and is therefore subject to periodic inspection. In this case, the parts should be replaced systematically.

  Although the embodiments of the present invention have been described, these embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 19 ... Base material, 20 ... Abradable coating layer, 21 ... Groove-shaped pocket, 22 ... Slit, 200 ... Steam valve main body, 201 ... Bush, 202 ... Upper lid, 203 ... Valve seat, 204 ... Valve body, 205 ... Valve Rod 206, hydraulic drive mechanism, 207, 208, 209 ... opening, 210 ... steam chamber, 301 ... seal member, 302 ... bolt, 303a, 303b ... protective cover, 304 ... inner edge, 401 ... seal part, 401 ... seal Numeral: 402, annular block, 403: fixed block, 700: boiler, 701, 703 ... valve, 702 ... steam control valve, 704 ... intercept valve, 705 ... high pressure turbine bypass valve, 706 ... low pressure turbine bypass valve, 707 ... reverse Stop valve, 710 ... high pressure turbine, 711 ... medium pressure turbine, 712 ... low pressure turbine, 713 ... condenser, 714 ... Water pump.

Claims (7)

A valve stem with a valve body at the tip;
A steam inlet, an outlet through which the steam flowing in from the inlet flows out, and an opening provided to face the outlet; and the valve body inserted into the valve body by the axial movement of the valve stem. A valve body for opening and closing the outlet,
A valve stem support portion provided at an upper portion of the opening of the valve body so as to surround the valve stem, and supporting the valve stem moving in an axial direction;
The valve body is fixed to the valve stem support portion at the position of the opening, and has an annular inner edge portion through which the valve rod passes, and the inner edge portion includes a material softer than an oxide attached to the valve stem. A steam valve device. The seal portion is
An annular block having the annular inner edge and loosely fitted to the shaft of the valve stem;
The steam valve device according to claim 1, further comprising: a fixed block that is fixed to the valve stem support portion and slidably supports the annular block in a direction orthogonal to the axis of the valve stem. Steam valve assembly according to claim 1 or 2 Izu he described comprising a machinability forming gap film on a surface of the inner edge of the sealing portion. Cobalt-based hard alloy on the surface of the valve stem, chromium single layer oxide film and the steam valve assembly as claimed in any one of claims 1 to 3 comprising one of the nitride film. On the inner edge of the seal part,
The steam valve device according to any one of claims 1 to 4, wherein grooves or slits are formed in a longitudinal direction and / or a lateral direction.   The steam valve device according to any one of claims 1 to 5, wherein a material having the same expansion coefficient as the valve stem or the same material as the valve stem is used for the seal portion.   A power generation facility comprising the steam valve device according to any one of claims 1 to 6.

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