Yarn and gland packing

Abstract

To provide a gland packing that can be used even under a high-temperature and high-pressure use condition.SOLUTION: A yarn includes: a cylindrical member configured by knitting a metal wire; and a filling fiber that is filled into the cylindrical member, where the filling fiber is constituted of at least one fiber material selected from an alumina fiber, a silicon carbide fiber, a boron fiber, an AES fiber, and a basalt fiber. A gland packing is constituted of braiding a plurality of the yarn.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to yarns and gland packings. [Background technology]

[0002] Conventionally, fluid devices such as pumps and valves are equipped with gland packings, which are shaft sealing components. A known example of such a gland packing is one made by braiding a plurality of yarns (see, for example, Patent Document 1). The yarn described in Patent Document 1 is constructed by filling a cylindrical member made by knitting wires with a plurality of filler materials formed into strips. In this yarn, the filler material used is, for example, an expanded graphite material.

[0003] Recently, thermal storage technology using molten salt has been investigated as a renewable energy source for achieving carbon neutrality. Molten salt thermal storage power generation equipment, one example of this thermal storage technology, converts electricity into heat using a rotating heating machine, stores the heat in high-temperature molten salt, and uses the molten salt as a heat source to generate steam when needed to drive a turbine generator. Gland packing is also used in such molten salt thermal storage power generation equipment, but in this case, it is sometimes required to be able to withstand an operating temperature of 900°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-11667 Summary of the Invention [Problem to be solved by the invention]

[0005] Expanded graphite oxidizes and disappears when heated above 400°C in an oxygen atmosphere. Therefore, gland packings that use expanded graphite as a filler are not suitable for use at 900°C. Ceramic fiber etc. can be considered as a constituent material for gland packing that is planned to be used at 900°C. Ceramic fiber has excellent heat resistance, so it may be suitable as a constituent material for gland packing that is used at high temperatures.

[0006] On the other hand, ceramic fibers are generally manufactured through a spinning process. Ceramic fibers manufactured through a spinning process have a spun fiber structure. Therefore, when ceramic fibers are used for gland packing, they have the following drawbacks: The first drawback is that they tend to have low abrasion resistance, which means they are less able to withstand friction and rubbing, making them unsuitable for use under high pressure conditions. The second drawback is poor fiber bonding: ceramic fibers produced through the spinning process tend to have loose bonds between the fibers, which means the fibers are not tightly bound together.

[0007] Because ceramic fibers have these drawbacks, it has been difficult to use gland packings made of braided ceramic fibers alone in applications requiring high pressure resistance.

[0008] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a gland packing that can be used under high temperature (e.g., operating temperature 900°C) and high pressure (e.g., operating pressure 40 MPa) conditions. [Means for solving the problem]

[0009] (1) The yarn of the present disclosure includes a tubular member formed by knitting metal wires and a filling fiber filled into the tubular member, The filling fibers are made of at least one fiber material selected from the group consisting of alumina fibers, silicon carbide fibers, boron fibers, AES fibers, and basalt fibers.

[0010] The yarn is composed of a filling fiber made of at least one fiber material selected from alumina fiber, silicon carbide fiber, boron fiber, AES fiber, and basalt fiber, and a tubular member surrounding the filling fiber. These fiber materials have a high heat resistance of 900°C or higher. Therefore, the yarn has excellent heat resistance and abrasion resistance. Therefore, this yarn can provide a gland packing that can be used under high temperature and high pressure conditions.

[0011] (2) In the yarn of (1) above, the wire is preferably made of a nickel alloy. This wire is suitable for protecting the filler fibers and ensuring good abrasion resistance.

[0012] (3) The yarn of (1) or (2) above preferably has an inorganic filler impregnated into the filler fibers. In this case the yarn has better abrasion resistance.

[0013] (4) The gland packing of the present disclosure is formed by braiding a plurality of yarns according to any one of (1) to (3) above. The gland packing of the present disclosure can be suitably used even under high temperature and high pressure conditions. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a gland packing that can be suitably used even under high-temperature and high-pressure conditions, and a yarn for producing such a gland packing. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a part of a fluid device provided with a gland packing according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the gland packing of FIG. [Figure 3]FIG. 3 is a front view showing a part of the yarn according to the embodiment. [Figure 4] FIG. 4 is a diagram showing a method for manufacturing a yarn according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, preferred embodiments will be described with reference to the accompanying drawings. [Gland packing configuration] 1 is a cross-sectional view showing a part of a fluid device equipped with a gland packing according to an embodiment. The fluid device is, for example, a pump, a valve, or a dresser joint, and includes a packing box 1, a shaft 2 disposed in the packing box 1, and a plurality of gland packings 3 that seal between the packing box 1 and the shaft 2.

[0017] The shaft 2 rotates about an axis C of the shaft 2 and moves back and forth in the axial direction relative to the packing box 1. In the fluid equipment shown in Fig. 1, the axis C of the shaft 2 is arranged vertically, but in fluid equipment equipped with the gland packing 3, the axis C may be arranged horizontally.

[0018] The gland packings 3 are each formed in an annular shape and are arranged side by side in the axial direction in an annular space A formed in the packing box 1. The annular space A is defined by an inner circumferential surface 1a and a stepped surface 1b on the atmosphere side of the packing box 1 and an outer circumferential surface 2a of the shaft 2.

[0019] The gland packings 3 are pressed against the interior side (lower side in Fig. 1) by a packing gland 4 arranged on the atmosphere side (upper side in Fig. 1) of the annular space A. The packing gland 4 is cylindrical and has an annular flange portion 4a. A plurality of bolts 5 (only one bolt is shown in Fig. 1) pass through the flange portion 4a in the axial direction in the circumferential direction, and each of these bolts 5 is threaded into a threaded hole 6 formed in the end face of the packing box 1 on the atmosphere side.

[0020] By tightening the bolts 5, the packing gland 4 moves toward the inside of the machine, pressing each gland packing 3 toward the inside of the machine. This causes each gland packing 3 to be crushed in the axial direction, and the outer peripheral surface 3a and inner peripheral surface 3b of each gland packing 3 come into close contact with the inner peripheral surface 1a of the packing box 1 and the outer peripheral surface 2a of the shaft 2, which are radially opposed to each other. In this way, each gland packing 3 prevents the sealed fluid in the fluid equipment from leaking to the atmosphere.

[0021] 2 is a perspective view showing the gland packing 3. The gland packing 3 is formed by rolling a string-like member 3', which is made by braiding a plurality of yarns 12 around a core material 11, into a ring shape and compression molding it. As a result, the gland packing 3 is formed into a ring shape with a rectangular cross section. The core material 11 may be made of yarn 12 or another material.

[0022] Examples of fluid equipment suitable for use with the gland packing 3 include molten salt thermal storage power generation equipment. Specifically, the gland packing 3 is suitable for use in a valve in a pipe through which a heat exchange medium flows in a molten salt thermal storage power generation equipment.

[0023] [Yarn composition] 3 is a front view showing a part of the yarn 12 according to the embodiment. The yarn 12 constitutes the gland packing 3. The yarn 12 includes a tubular member 13 and filler fibers 14 filled in the tubular member 13. In other words, the yarn 12 has the filler fibers 14 wrapped around the tubular member. The yarn 12 is constructed by filling the tubular member 13 with the length direction of the filling fibers 14 aligned along the axial direction of the tubular member 13. In the yarn 12, the sides of the filling fibers 14 are covered with knitted wires. The filler fiber 14 is made of a fibrous material and may be, for example, made of a single twisted thread or a plurality of twisted threads arranged side by side.

[0024] The tubular member 13 is formed by knitting wire 16 to form stitches 15. The wire 16 is made of a metal such as an iron-based alloy such as stainless steel, or a nickel-based alloy such as Inconel or Monel. By knitting the wire 16, the wire 16 has a plurality of arc portions 16a formed into an arc shape and linear portions 16b extending linearly from both ends of each arc portion 16a.

[0025] From the viewpoint of excellent heat resistance, a nickel alloy is preferable as the material of the wire 16. A more preferable material of the wire 16 is Inconel.

[0026] The arc portions 16a are arranged in a spiral pattern in the circumferential direction of the cylindrical member 13, and adjacent arc portions 16a are arranged so that they protrude in opposite directions. The straight portions 16b are arranged in a spiral pattern at predetermined intervals in the circumferential direction of the cylindrical member 13.

[0027] The stitches 15 are formed by a pair of linear portions 16b adjacent to each other in the circumferential direction, an arc portion 16a connecting one longitudinal end of the linear portions 16b, and another arc portion 16a arranged across the other longitudinal end of the linear portions 16b. As a result, the tubular member 13 is formed with a plurality of stitches 15 arranged continuously in a spiral shape in the circumferential direction, and these stitches 15 are formed to be of a generally uniform size.

[0028] In FIG. 3, angle θ is the angle formed between a center line K extending in the longitudinal direction of each stitch 15 and an axis P of the tubular member 13. 3, the angle θ is not 0°. In other words, each stitch 15 is formed at an angle with respect to the axis P of the tubular member 13. In the yarn according to the embodiment of the present disclosure, the angle θ may be 0°.

[0029] The filling fibers 14 are composed of at least one type of fiber material selected from alumina fibers, silicon carbide fibers, boron fibers, AES fibers, and basalt fibers. The filling fibers 14 may be composed of one type of fiber material or two or more types of fiber materials. These fiber materials have excellent heat resistance, specifically, a high heat resistance temperature of 900° C. or more. The heat resistance temperature of the fiber material refers to the softening temperature of the fiber material.

[0030] As the fiber material, basalt fiber is preferred from the viewpoint of low thermal loss. The above-mentioned fiber materials may be commercially available products.

[0031] Alumina fibers are fibers containing alumina (Al2O3) as a main component and silica (SiO2). The composition of the alumina fibers is, for example, 72 to 97 mass% Al2O3 and 3 to 28 mass% SiO2.

[0032] Silicon carbide fibers are fibers whose main component is SiC. Boron fibers are fibers produced by depositing boron by chemical vapor deposition (CVD).

[0033] AES (alkaline earth silicate) fibers are man-made mineral fibers that are primarily composed of SiO2, MgO, and CaO and may contain small amounts of oxides such as Al2O3, TiO2, and ZrO2. The composition of the AES fibers is, for example, 50 to 82 mass% SiO2 and 18 to 43 mass% MgO and CaO in total.

[0034] Basalt fiber is a fiber made from basalt. For example, basalt is melted in a furnace and extruded and spun into fibers.

[0035] The diameter of the filling fibers 14 is not particularly limited, and is selected taking into consideration the diameter of the yarn 12, the number of twisted yarns that make up the filling fibers 14, and the like.

[0036] The yarn 12 may have an inorganic filler (not shown) impregnated into the filler fibers 14. In this case, the abrasion resistance of the yarn 12 is improved, making the yarn more suitable for forming a gland packing used under high-pressure conditions. When the yarn 12 has an inorganic filler in this way, the inorganic filler is present on the surface or inside of the filler fibers 14.

[0037] Examples of the inorganic filler include particles mainly composed of alumina, particles mainly composed of boron nitride, graphite powder, particles mainly composed of molybdenum disulfide, particles mainly composed of silica, etc. These inorganic fillers are suitable for improving the abrasion resistance of the yarn. The shape of the inorganic filler is not particularly limited, and examples thereof include spherical, scaly, fibrous, and plate-like shapes. The method for impregnating the inorganic filler will be described later.

[0038] In the yarn 12, the proportion of the filler fibers 14 to the total amount of the tubular member 13 and the filler fibers 14 is preferably 65% by mass or more and 85% by mass or less. In this case, the tubular member 13 and the filling fiber 14 are contained in a good balance, which is suitable for achieving both excellent heat resistance and excellent pressure resistance.

[0039] The cross-sectional shape of the yarn 12 perpendicular to the axis P of the tubular member 13 may be a circle, an ellipse, or other flattened circle. The yarn 12 can be manufactured using, for example, the manufacturing apparatus described below.

[0040] [Yarn manufacturing equipment] 4 is a schematic diagram showing an example of a manufacturing apparatus for manufacturing the yarn 12. This manufacturing apparatus 30 includes a supply mechanism 31, a guide supply mechanism 33, a knitting machine 35, and a control unit 37.

[0041] The supply mechanism 31 has a reel 41 around which a yarn 42 (a twisted yarn constituting the filler fiber) is wound. The supply mechanism 31 has three reels 41. Each reel 41 is rotatably mounted on a rotation shaft 43. When each reel 41 rotates in the direction of arrow A shown in FIG. 4, the supply mechanism 31 unwinds the yarn 42 and sends it out toward the guide supply mechanism 33.

[0042] The guide supply mechanism 33 has a guide reel 45 and a cylindrical guide tube 49. The guide reel 45 is rotatably mounted on a rotary shaft 47. The guide reel 45 has a plurality of guide grooves arranged in the axial direction. The yarns 42 fed from each reel 41 are transported along the guide grooves of the guide reel 45 and their direction is changed. The yarns 42 whose direction has been changed by the guide reel 45 are transported into the guide tube 49 in a lined up state. The yarns 42 that have passed through the guide tube 49 are supplied to the knitting machine 35. In the guide supply mechanism 33, the guide tube 49 may be omitted.

[0043] The knitting machine 35 is equipped with a plurality of knitting needles (not shown), and is configured to knit the wire 16 with these knitting needles to form the tubular member 13. The knitting machine 35 knits the wire 16 so that the cross-sectional shape of the tubular member 13 perpendicular to the axis P is a perfect circle.

[0044] The knitting machine 35 continues knitting the wire 16 so that the upper end opening of the tubular member 13 is held directly below the lower end opening 51 of the guide tube 49, and sends it downward while forming a tubular portion (a part of the tubular member 13). In this way, the knitting machine 35 forms the tubular member 13 having a predetermined axial length.

[0045] At this time, the yarn 42 guided to the inlet 53 of the knitting machine 35 by the guide supply mechanism 33 is continuously introduced into the tubular member 13 from the upper end opening thereof, from a stage during the formation of the tubular member 13. As a result, the tubular member 13 is filled with the filler fibers 14, and a yarn material 59 is formed. The formation of this yarn material 59 may be considered as the completion of the yarn 12. Alternatively, the cross-sectional shape of the yarn material 59 may be deformed into a flattened circle or the like, and then the yarn 12 may be completed.

[0046] As shown in FIG. 4, the control unit 37 is configured to control the driving of the supply mechanism 31 (rotation of the reel 41) and the driving of the knitting machine .

[0047] In the manufacturing apparatus 30 configured as described above, a process is performed in which the knitting machine 35 knits the wires 16 to form the tubular member 13 while filling the tubular member 13 with the filling fibers 14, thereby obtaining a yarn material 59 having a perfectly circular cross section perpendicular to the axis P of the tubular member 13. In this way, the yarn 12 can be manufactured.

[0048] The method for producing the yarn 12 may further include an inorganic filler impregnation step. In this impregnation process, the obtained yarn material 59 is immersed in an inorganic filler dispersion in water, and then dried. By performing this impregnation process, a yarn 12 having inorganic filler impregnated into the filler fibers can be obtained. In this impregnation step, the concentration of the inorganic filler in the dispersion, the immersion time of the yarn material 59, the drying conditions, etc. may be selected as appropriate.

[0049] [Action and effect] The yarn according to this embodiment includes a filler fiber made of a fiber material having a high heat resistance temperature and a tubular member in which a knitted metal wire is wrapped around the filler fiber. This yarn has excellent heat resistance because of the high heat resistance of the fiber material. Furthermore, the yarn also has excellent abrasion resistance because the filler fiber is wrapped around the knitted metal wire. Therefore, according to this embodiment, since a plurality of the above-mentioned yarns are braided together, it is possible to provide a gland packing that can be used even under high temperature (e.g., 900°C) and high pressure (e.g., 40 MPa) conditions.

[0050] Furthermore, in the yarn according to this embodiment, basalt fiber is used as the fiber material constituting the filling fiber, and Inconel wire is used as the wire constituting the tubular member, thereby providing a yarn with excellent performance, such as high abrasion resistance, heat resistance, and corrosion resistance, and low thermal weight loss when used under high temperature conditions.

[0051] [others] The gland packing 3 is not limited to the above embodiment as long as it is formed by braiding a plurality of yarns 12 of the above embodiment.

[0052] When manufacturing a gland packing having a yarn having an inorganic filler impregnated into the filling fiber, the gland packing may be manufactured by braiding a yarn that is not impregnated with the inorganic filler, immersing the resulting braided body in a dispersion of the inorganic filler, and then drying the braided body.

[0053] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0054] 3 Gland packing 11 Core material 12 yarns 13 Cylindrical member 14 Filling Fiber Stitch 15 16 wire rod 30 Manufacturing equipment (for manufacturing yarn) P axis

Claims

1. The present invention comprises a tubular member formed by knitting metal wires, and a filling fiber filled in the tubular member, The yarn, wherein the filler fibers are composed of at least one fiber material selected from the group consisting of alumina fibers, silicon carbide fibers, boron fibers, AES fibers, and basalt fibers.

2. The yarn of claim 1 , wherein the wire is a nickel alloy wire.

3. The yarn of claim 1 having an inorganic filler impregnated in the filler fibers.

4. A gland packing formed by braiding a plurality of yarns according to any one of claims 1 to 3.

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