JP2020029867A - Valve device - Google Patents

Abstract

To provide a valve device capable of reducing abrasion of a ceramic valve seat.SOLUTION: In a valve device 10 for adjusting a flow rate on the basis of a distance between a plug 12 and a valve seat 14, the valve seat 14 is fixed to a main body 11 of the valve device 10 through a seat holding member 16. The valve seat 14 is composed of a cylindrical body, the cylindrical body has a shaft center along a flowing direction of fluid, and an outer periphery of the cylindrical body is tapered to a downstream side in the flowing direction of the fluid. As the valve seat 14 has such a shape, a clearance is not formed between the valve seat 14 and the seat holding member 16. According to this constitution, the valve seat 14 does not vibrate to the seat holding member 16, so that degradation of abrasion resistance of ceramics of the valve seat 14 can be suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a valve device. More specifically, the present invention relates to a valve device for adjusting a flow rate by a distance between a plug (valve element) and a valve seat (valve seat).

  BACKGROUND ART In a plant facility or the like, a substance may be transported in a multiphase flow in which a plurality of phases (a gas phase, a liquid phase, or a solid phase) of the substance are mixed. In such a multiphase flow, abrasion due to collision of solid particles in a substance conveyed in the state of the multiphase flow is likely to occur in a member contacted by the multiphase flow. In addition, since cavitation is likely to occur, wear is increased by a change in the flow rate in a low cycle. Therefore, a member of a valve device provided at an outlet or an inlet of a substance to a device constituting a plant facility is required to have high wear resistance.

  FIG. 5 shows a front sectional view of a conventional valve device 50. In this valve device 50, the plug 52 is moved up and down with respect to the valve seat 54 fixed to the valve body 51, and the flow rate flowing through the valve device 50 is adjusted according to the distance between the plug 52 and the valve seat 54. The plug 52 is guided by a plug guide 53 and is moved up and down by a stem 55. In the valve device 50, as shown by the arrow in FIG. 5, the fluid flows in the horizontal direction (from left to right on the paper surface of FIG. 5), passes through the contraction portion between the plug 52 and the valve seat 54, and It flows out in the vertical direction (from the top to the bottom in FIG. 5). When the fluid has a high temperature and a high pressure, a part of the fluid may be vaporized in a decompression stage inside the valve device 50 to become a gas-liquid mixed fluid. In this case, cavitation is likely to occur in the contraction section due to reduced pressure.

  Patent Literature 1 discloses a valve device that employs ceramics as a member of a seat ring (valve seat) in contact with a valve plug to ensure high wear resistance. When ceramics is adopted as the member of the valve seat as described above, a member that holds and holds the valve seat (holding cylinder 51 in Patent Document 1) is used for fixing the valve device to the main body side. This is because complicated processing such as threading and drilling cannot be performed on ceramics having high wear resistance, that is, high hardness, in order to avoid stress concentration. In this case, as shown in FIG. 5, in order to hold the valve seat 54, a metal receiving portion provided downstream of the holding member (corresponding to the seat holding member 56 in FIG. 5) in the fluid flow direction. May need to be retained. At that time, the metal receiving portion comes into contact with the fluid, so that abrasion tends to proceed.

Japanese Utility Model Publication No. 1-148174

  The valve seat usually has a cylindrical shape (a shape having an outer peripheral surface equidistant from the axis). In order to fit this valve seat into the cylindrical recess of the holding member of the valve seat, the inner periphery of the holding member is provided with a predetermined fitting tolerance with respect to the outer periphery of the valve seat, that is, the inner periphery of the valve seat and the inner periphery of the holding member. It is necessary to have a gap between the circumference. In addition, since the holding member is made of metal, the coefficient of thermal expansion is larger than that of ceramics, and when the temperature of the entire valve device becomes high, the gap between the holding member and the valve seat increases. Due to this gap, the valve seat vibrates at a high frequency due to the flow of the fluid, and the wear of the valve seat may progress despite the use of ceramics having high wear resistance.

  In view of the above circumstances, an object of the present invention is to provide a valve device that can reduce wear of a ceramic valve seat.

A valve device according to a first aspect of the present invention is a valve device for adjusting a flow rate by a distance between a plug and a valve seat, wherein the valve seat is fixed to a main body of the valve device via a seat holding member. The valve seat is a tubular body having an axis along the flow direction of the fluid,
The outer periphery thereof is formed in a taper shape in which the downstream side in the flow direction becomes narrower, and the sheet holding member is provided with a taper receiving surface facing the taper.
A valve device according to a second invention is characterized in that, in the first invention, the taper is equal to or greater than 1/200 and equal to or less than 1/50.
In the valve device according to a third aspect, in the first aspect or the second aspect, sealing between the seat holding member and the main body is performed by an O-ring, and a screw connection between the seat holding member and the main body is performed. The O-ring is provided on an upstream side in the flow direction from a portion.
A valve device according to a fourth aspect of the present invention is the valve device according to any one of the first to third aspects, wherein a non-contact portion with the tapered receiving surface is provided on an outer periphery of the tubular body of the valve seat. Are sandwiched by a contact portion with the tapered receiving surface in the direction of the axis.

According to the first invention, since the outer periphery of the tubular body of the valve seat and the inner periphery of the seat holding member are formed in a tapered shape in which they are in close contact with each other, a gap is generated between the valve seat and the seat holding member. Disappears. With this configuration, the valve seat does not vibrate with respect to the seat holding member, and a decrease in the wear resistance of the ceramic of the valve seat can be suppressed. Further, even when the temperature of the valve device becomes high, the gap between the valve seat and the seat holding member does not increase, and in this regard, it is also possible to suppress a decrease in the wear resistance of the ceramic of the valve seat. When the valve seat is held by the metal receiving portion provided on the downstream side in the flow direction of the fluid of the seat holding member, wear of the metal receiving portion can be prevented.
According to the second aspect, since the taper is not less than 1/200 and not more than 1/50, it is possible to prevent the gap on the side where the diameter of the taper is large from becoming too large when the temperature rises, and to provide a valve for the seat holding member. Sheet positioning becomes easy. Further, the valve seat does not drop off downstream in the flow direction.
According to the third aspect, the O-ring for sealing between the sheet holding member and the main body is provided on the upstream side in the flow direction from the screw connecting portion between the sheet holding member and the main body. Corrosion can be prevented.
According to the fourth invention, since the non-contact portion with the tapered receiving surface is provided on the outer periphery of the tubular body of the valve seat, the valve seat is easily removed from the seat holding member when replacing the valve seat. be able to. Further, since the non-contact portion with the taper receiving surface is sandwiched between the contact portions with the taper receiving surface in the direction of the axis, the contact portion between the taper surface and the taper receiving surface is separated, and the seat is separated. The posture of the valve seat with respect to the holding member is more stable.

It is a sectional view from the front direction of the valve device concerning a 1st embodiment of the present invention. (A) is sectional drawing from the front direction of the valve seat of the valve apparatus of FIG. FIG. 2B is a cross-sectional view of the seat holding member of the valve device of FIG. 1 as viewed from the front. It is sectional drawing from the front direction of the valve apparatus which concerns on 2nd Embodiment of this invention. (A) is sectional drawing from the front direction of the valve seat of the valve apparatus which concerns on 3rd Embodiment of this invention. (B) is a sectional view from the front of a seat holding member of a valve device according to a third embodiment of the present invention. It is sectional drawing from the front direction of the conventional valve apparatus.

  Next, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a valve device 10 for embodying the technical idea of the present invention, and the present invention does not specify the valve device 10 as follows. In addition, the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of description. Further, in the following description, the same names and reference numerals denote the same or similar members, and a detailed description thereof will be omitted as appropriate.

(1st Embodiment)
FIG. 1 is a cross-sectional view of a valve device 10 according to a first embodiment of the present invention as viewed from the front, and FIG. 2 is a valve seat 14 and a seat holding member 16 that constitute the valve device 10 according to the first embodiment. 2 shows a sectional view from the front direction of FIG. FIG. 2A is a sectional view of the valve seat 14, and FIG. 2B is a sectional view of the seat holding member 16.

  In the valve device 10 according to the first embodiment of the present invention, the plug 12 is moved up and down with respect to the valve seat 14 fixed to the main body 11, and the valve device 10 is moved by the distance between the plug 12 and the valve seat 14. To adjust the flow rate of the fluid flowing through. The plug 12 is guided by a plug guide 13 and driven up and down by a stem 15. In the valve device 10, as shown by the arrow in FIG. 1, the fluid flows in from the horizontal direction (from left to right on the paper surface of FIG. 1), passes through the contraction portion between the plug 12 and the valve seat 14, It flows out in the vertical direction (from the top to the bottom in FIG. 1). The valve device 10 of the present invention can reduce abrasion of a ceramic valve seat, for example, even when a high-temperature and high-pressure fluid flows.

  In the valve device 10 according to the present embodiment, the valve seat 14 is fixed to the main body 11 of the valve device 10 via the seat holding member 16. That is, in the valve device 10, the seat holding member 16 is inserted into an insertion hole for inserting the seat holding member 16 provided in the main body 11 of the valve device 10, and further, the valve is inserted into the through hole 16 a of the seat holding member 16. This is a configuration in which the seat 14 is arranged.

  The valve seat 14 is made of ceramics in consideration of wear resistance. Fine ceramics that are often used industrially include, for example, boron nitride, silicon nitride, ferrite, and the like. In the present embodiment, in consideration of wear resistance in a high-temperature acidic and oxidizing atmosphere, a valve is used. The material of the sheet 14 is aluminum oxide.

  The valve seat 14 has the shape of a cylindrical body having a concentric cross section. The outer periphery of the cylindrical body is tapered such that the diameter on the downstream side in the fluid flow direction decreases. That is, on the paper surface of FIG. 1 or FIG. 2, the diameter of the outer periphery of the cylindrical body decreases from the upper side to the lower side. Further, as shown in FIG. 2A, a line representing the taper of the outer periphery of the cylindrical body is a straight line. That is, the diameter of the outer periphery of the cylindrical body decreases from the upper side to the lower side at a constant rate. The taper may be formed over the entire outer periphery of the valve seat 14 or may be formed partially. The inner circumference has a passage hole 14a having the same inner diameter from the upper side to the lower side. The fluid passes through the passage hole 14a. The shape of the passage hole 14a is not limited to this.

  Here, as shown in FIG. 2A, when the upper diameter of the valve seat 14 is L1, the lower diameter of the valve seat 14 is L2, and the length of the valve seat 14 in the axial direction is L3, the taper is Is represented as (L1-L2) / L3. In the present embodiment, it is preferable that the taper is not less than 1/200 and not more than 1/50.

  If the taper is smaller than 1/200, it becomes difficult to secure processing accuracy for positioning the valve seat 14 with respect to the seat holding member 16, and the large diameter side of the valve seat 14 protrudes from the upper end surface 16 b of the seat holding member 16. , And often become depressed. Further, in a use mode in which the substance is conveyed in a multiphase flow state at a high flow velocity toward the downstream side in the flow direction, the valve seat may fall to the downstream side in the flow direction. Further, if the taper is larger than 1/50, the valve seat 10 and the seat holding member 16 may be separated by a difference in coefficient of thermal expansion when the valve device 10 is heated to a high temperature in a portion where the outer diameter of the cylindrical body is large. The gap between them is too large.

  The seat holding member 16 is made of metal having a larger coefficient of thermal expansion than ceramics such as aluminum oxide used as a material of the valve seat 14, and is made of stainless steel in consideration of easiness of processing, corrosion resistance, and availability. is there. More specifically, SUS316L, which is an austenitic stainless steel, is desirable.

  The seat holding member 16 has a through hole 16a having a tapered receiving surface on the inner periphery so that the valve seat 14 is fitted. The through hole 16a has a taper receiving surface that opposes the taper of the valve seat 14. And this taper receiving surface has a structure to which the valve seat 14 can adhere. That is, the taper receiving surface is a taper in which the inner diameter on the downstream side in the fluid flow direction becomes smaller. Further, as shown in FIG. 2B, the line representing the taper of the inner periphery of the through hole 16a is a straight line. That is, the diameter of the inner circumference of the tapered receiving surface decreases from the upper side to the lower side at a constant rate. The size of the inner diameter of the taper receiving surface is such that the upper end of the valve seat 14 substantially matches the upper end surface 16b of the seat holding member 16 when the valve seat 14 is fitted. In addition, the tapered receiving surface may cover the entire inner surface of the through hole 16a or may be a part.

  The upper and lower positions of the sheet holding member 16 with respect to the main body 11 are determined by a shoulder 16d provided at an upper portion. Before the plug guide 13 and the like are assembled, the sheet holding member 16 is inserted from above in the plane of FIG. 1 and is screwed by being rotated about the axis of the sheet holding member 16. A male screw 16c is provided on the outer periphery of the sheet holding member 16, and when a circumferential force is applied to the projection by a jig or the like, the sheet holding member 16 rotates and is screwed and fastened to the main body 11. You.

  Since the outer periphery of the tubular body of the valve seat 14 is tapered such that the downstream side in the flow direction becomes thinner, no gap is formed between the valve seat 14 and the seat holding member 16. With this configuration, the valve seat 14 does not vibrate with respect to the seat holding member 16. When the valve seat 14 vibrates, uneven wear may occur even when the valve seat 14 is made of a ceramic having wear resistance. However, when the valve seat 14 is fixed to the seat holding member 16 by the taper, the valve The occurrence of uneven wear of the sheet 14 is suppressed, high wear resistance of the ceramics can be secured, and a decrease in wear resistance is suppressed.

  In addition, when the valve device 10 is heated to a high temperature, in the case of a conventional cylindrical shape (a shape having an outer peripheral surface equidistant from the axis), the gap is further increased due to a difference in coefficient of thermal expansion. Since the valve seat 14 is further fitted into the holding member 16 (the valve seat 14 moves slightly downward in FIG. 1), the gap between the valve seat 14 and the seat holding member 16 does not increase, Also in this respect, the valve seat 14 is fixed to the seat holding member 16, and a decrease in wear resistance is suppressed.

  When the taper is not less than 1/200 and not more than 1/50, it is possible to prevent the gap on the side where the diameter of the taper is large from becoming too large when the temperature rises, and to position the valve seat 14 with respect to the seat holding member 16. It will be easier. In addition, the valve seat 14 does not drop to the downstream side in the flow direction.

(2nd Embodiment)
FIG. 3 is a sectional view of a valve device 10 according to a second embodiment of the present invention as viewed from the front. The present embodiment differs from the first embodiment in that an O-ring 17 is provided between the sheet holding member 16 and the main body 11.

  In the present embodiment, the sheet holding member 16 and the main body 11 are screwed. That is, the female screw 11a provided on the inner periphery of the insertion hole for inserting the sheet holding member 16 of the main body 11 and the male screw 16c provided on the outer periphery of the sheet holding member 16 allow the main body 11 to be seated. The holding member 16 is screwed.

  In the present embodiment, an O-ring 17 is provided on the upstream side of the fluid from a portion where the sheet holding member 16 and the main body 11 are screw-connected. The provision of the O-ring 17 prevents the corrosive fluid from leaking out of the O-ring 17 to the downstream side.

  There is no problem as long as the material of the O-ring 17 is a material having high heat resistance to the operating temperature. For example, if the use temperature is about 200 ° C., Teflon (registered trademark) -based or fluorine-based rubber is suitably used as the material.

  Since the O-ring 17 for sealing between the sheet holding member 16 and the main body 11 is provided on the upstream side in the flow direction from the screw connecting portion between the sheet holding member 16 and the main body 11, corrosion of the screw connecting portion is prevented. Can be prevented. The female screw 11a is made of the same material as the main body 11, and the male screw 16c is made of the same material as the sheet holding member 16. However, since the threaded portion is finely processed with irregularities, even if the threaded portion is similarly in contact with a corrosive fluid, the threaded portion is more corroded. Therefore, by preventing the fluid from entering the threaded portion by the O-ring 17, corrosion of the threaded joint can be effectively prevented. Note that a groove for holding the O-ring may be provided in a portion of the sheet holding member 16 where the O-ring 17 contacts.

  The configuration using the O-ring 17, which is a feature of the valve device 10 according to the present embodiment, does not have the feature of the valve device 10 according to the first embodiment, that is, the valve seat 14 has a normal cylindrical shape (shaft and shaft). (A shape having an outer peripheral surface at the same distance).

(Third embodiment)
FIG. 4 is a cross-sectional view of the valve seat 14 and the seat holding member 16 constituting the valve device 10 according to the third embodiment as viewed from the front. FIG. 4A is a sectional view of the valve seat 14, and FIG. 4B is a sectional view of the seat holding member 16.

  The difference of the present embodiment from the first embodiment is that a non-contact portion 14b with the tapered receiving surface of the seat holding member 14 is provided on the outer periphery of the tubular body of the valve seat 14. The non-contact portion 14b is a concave portion and is provided over the entire circumference of the valve seat 14. However, in the axial direction of the valve seat 14, it is sandwiched between the contact portions 14c with the tapered receiving surface.

  The non-contact portion 14b with the tapered receiving surface is provided on the outer periphery of the tubular body of the valve seat 14, and the contact area between the valve seat 14 and the seat holding member 16 is reduced. In addition, the valve seat 14 can be easily removed from the seat holding member 16. Since the valve seat 14 and the seat holding member 16 are in contact with each other by the taper, there is a case where the valve seat 14 and the seat holding member 16 are fixed by the prolonged contact with the corrosive fluid. For this reason, when removing and replacing the valve seat 14 from the seat holding member 16, it takes time and effort to remove the valve seat 14, and in some cases, it is necessary to break the valve seat 14. Due to the non-contact portion 14b, the contact area between the valve seat 14 and the seat holding member 16 does not become unnecessarily large, and the valve seat 14 can be easily removed from the seat holding member 16.

  Since the non-contact portion 14b with the tapered receiving surface is sandwiched between the contact portions 14c with the tapered receiving surface in the axial direction, the portions where the tapered surface and the tapered receiving surface are in contact with each other are separated from each other. As a result, the posture of the valve seat 14 with respect to the seat holding member 16 becomes more stable.

(Manufacturing process using the valve device 10 of the present invention)
The valve device 10 of the present invention is preferably provided in an autoclave for leaching the slurry containing the mixed sulfide containing nickel and cobalt under pressure, and can be used for adjusting the level of the slurry in the autoclave. With the valve device 10 of the present invention, breakage and wear of the valve device 10 used for level adjustment can be suppressed, and the operation rate and productivity of the plant equipment can be improved. Hereinafter, a nickel sulfate production process will be described as an example of a process in which a slurry containing a mixed sulfide containing nickel and cobalt is leached under pressure by an autoclave.

  A mixed sulfide (MS: Mixed Sulfide) containing nickel and cobalt is used as a raw material of nickel sulfate. This nickel-cobalt mixed sulfide is obtained by subjecting low-grade nickel oxide ore to high pressure acid leaching (HPAL) to remove impurities such as iron from the pressurized acid leaching solution, and then removing nickel ions and cobalt ions. It is obtained by a wet sulfurization reaction in which hydrogen sulfide gas is blown into the leachate containing the solution. The main component of the nickel-cobalt mixed sulfide is a sulfide such as NiS.

  Next, a repulp process is performed on the nickel-cobalt mixed sulfide. In this repulp process, the nickel / cobalt mixed sulfide is repulped with water or the like to form a slurry. In the repulping step, nickel-cobalt mixed sulfide in the form of solid powder is charged into a repulping tank, mixed with water, and stirred to produce a slurry. The slurry is charged into an autoclave and subjected to pressure leaching.

  Next, a pressure leaching step is performed. In this pressure leaching step, nickel and cobalt contained in the mixed sulfide are leached by high-pressure air by an autoclave. For example, the solid content of the slurry charged into the autoclave is 200 to 300 g / L, and the flow rate is 50 to 100 L / min. The temperature in the autoclave is 150 to 220 ° C., and the pressure is 1.7 to 2.3 MPa in gauge pressure.

  A pressurized leachate, which is a mixed aqueous solution of nickel sulfate and cobalt sulfate, is discharged from the autoclave. The pressurized leachate is supplied to the next step after being reduced in pressure and cooled, and used for the production of nickel sulfate. The valve device 10 of the present invention is optimally used as an extraction valve (autoclave level control valve) for extracting the leached slurry from the autoclave and transferring the slurry to a pressure reducing device (flash tank).

  The slurry after the leaching is not only a high temperature and a high pressure but also a slurry containing a leaching residue of hard MS. And a liquid phase and a solid phase are mixed with each other.

  The valve device 10 of the present invention can be used as an autoclave level control valve as described above, but is not limited thereto, and can be used in other facilities and other applications. For example, it can also be used as a pressure control valve of an autoclave.

DESCRIPTION OF SYMBOLS 10 Valve apparatus 11 Main body 12 Plug 14 Valve seat 14b Non-contact part 14c Contact part 16 Seat holding member 17 O-ring

Claims (4)

A valve device for adjusting a flow rate according to a distance between a plug and a valve seat,
The valve seat is fixed to a main body of the valve device via a seat holding member,
The valve seat is a cylindrical body having an axial center along a fluid flow direction,
The outer periphery is formed in a taper in which the downstream side in the flow direction becomes narrower,
The sheet holding member is provided with a taper receiving surface facing the taper,
A valve device characterized by the above-mentioned. The taper is not less than 1/200 and not more than 1/50;
The valve device according to claim 1, wherein: A seal between the sheet holding member and the main body,
O-ring,
The O-ring is provided on the upstream side in the flow direction from a portion where the sheet holding member and the main body are screw-connected.
The valve device according to claim 1 or 2, wherein On the outer periphery of the tubular body of the valve seat, a non-contact portion with the tapered receiving surface is provided,
The non-contact portion is sandwiched between the contact portion with the tapered receiving surface in the direction of the axis,
The valve device according to any one of claims 1 to 3, characterized in that:

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