JP2010210126A - Gasket for plate type heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasket for a plate type heat exchanger having high durability even in a high-temperature environment. <P>SOLUTION: The gasket 12 is used for sealing a flow passage formed between heat transfer plates 11, 11 of the plate type heat exchanger. The gasket 12 includes: a central core rubber part 21 formed of rubber; and first and second canvas 31, 32 covering the outer peripheral faces of the central core rubber part 21. The first canvas 31 covers the outer peripheral faces of three sides out of the outer peripheral faces of the central core rubber part 21 having a hexagonal cross section. The second canvas 32 covers the outer peripheral faces of remaining three sides out of the outer peripheral faces of the central core rubber part 21 having the hexagonal cross section. The first and second canvas 31, 32 has stretchable woofs 34 arranged along the width direction of the gasket 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gasket for a plate heat exchanger used in, for example, a chemical plant or a food factory.

  In the plate heat exchanger, a large number of heat transfer plates are stacked at intervals, and a flow path is formed between adjacent heat transfer plates. In the plate heat exchanger, the flow path through which the low-temperature fluid flows and the flow path through which the high-temperature fluid flow are alternately formed, whereby heat exchange is performed between the low-temperature fluid and the high-temperature fluid. The heat transfer plate in the plate heat exchanger has a gasket groove formed so as to surround the flow path, and is laminated via a gasket fitted in the gasket groove. In the plate heat exchanger, the airtightness of the flow path is ensured by such a gasket.

  The gasket of the plate heat exchanger is generally made of a material having high heat resistance and chemical resistance because it contacts a high-temperature fluid flowing through the flow path. Specifically, the outer periphery of the rubber is coated with a fluororesin as described in Patent Document 1 as described in Patent Document 1, and the wetted surface is further covered with a resin sheet from above the coating. Coated ones are known.

JP 2004-301425 A

  However, when a fluid (for example, water vapor) having a temperature of 180 ° C. or higher is used as the high temperature fluid, the gasket formed of fluororubber tends to be permanently deformed, and cracks may occur when used for a long time. . Further, the gasket described in Patent Document 1 is also covered with a hard resin sheet on the outer periphery, so that the flexibility of the entire gasket is impaired, and the occurrence of cracks or the like cannot be sufficiently reduced. Further, these gaskets have a problem that the production cost is high because fluororubber is used for the whole rubber or the gasket structure is complicated.

  Accordingly, the present invention has been made in view of the above problems, and provides a plate heat exchanger gasket having a relatively simple structure and an inexpensive material, and having sufficient heat resistance and durability. For the purpose.

  A gasket according to the present invention is for sealing a flow path formed between heat transfer plates of a plate heat exchanger, and includes an inner core rubber portion formed of rubber and an outer periphery of the inner core rubber portion. And a canvas covering the surface.

  For example, the core rubber portion has a polygonal cross section, and the gasket includes first and second canvases that cover the outer peripheral surface of the core rubber portion. In this case, it is preferable that at least one side of the polygon is covered with the first canvas and the remaining side of the polygon is covered with the second canvas on the outer peripheral surface of the core rubber portion. More preferably, both ends of the first canvas are respectively connected to both ends of the second canvas at the vertexes of the polygon. For example, the entire circumference of the core rubber portion is covered with canvas.

  For example, at least a part of the yarn is made of elastic yarn, and the canvas preferably has elasticity, and the canvas more preferably has elasticity in the width direction of the gasket. In this case, the canvas is, for example, a woven fabric woven from a first thread disposed along the longitudinal direction of the gasket and a second thread disposed along the width direction of the gasket, The yarn is a non-stretchable yarn and the second yarn is a stretchable yarn. The canvas is preferably impregnated with rubber glue or coated with a coating agent.

  In the present invention, even when the gasket is used so as to be in contact with a high-temperature fluid of, for example, 180 ° C. or higher, cracks generated in the gasket can be suppressed and the durability of the gasket can be improved.

It is a perspective view showing an example of a plate type heat exchanger in a 1st embodiment of the present invention. It is a top view which shows the heat-transfer plate which comprises a plate type heat exchanger. It is a perspective view which shows the gasket and gasket groove | channel in 1st Embodiment. It is sectional drawing which shows the gasket in 1st Embodiment. It is sectional drawing which shows the gasket in 2nd Embodiment. It is sectional drawing which shows the gasket in 3rd Embodiment. It is sectional drawing which shows the modification of a gasket. It is sectional drawing which shows the modification of a gasket. It is sectional drawing which shows the modification of a gasket.

Embodiments of the present invention will be described below with reference to the drawings.
Drawing 1 is a figure showing an example of a plate type heat exchanger with which a gasket concerning a 1st embodiment of the present invention is installed. The plate heat exchanger 10 is configured by laminating a plurality of metal heat transfer plates 11 press-molded into wave shapes via gaskets 12. Each heat transfer plate 11 is provided with a fluid passage hole 13 for heat exchange medium at four corners, a heat transfer surface 14 at the center, and a gasket 12 is mounted so as to surround the heat transfer surface 14 and the fluid passage hole 13. Is done.

  As shown in FIG. 2, the gasket 12 includes upper and lower fluid passage holes 13 on one side of the heat transfer plate 11 and a large ring portion 12 a surrounding the heat transfer surface 14, and the remaining two fluid passage holes 13 of the heat transfer plate 11. It consists of a small ring portion 12b that encloses. Such heat transfer plates 11 are vertically inverted and laminated by 180 °, and as shown in FIG. 1, the first solid arrow indicated by the solid line in which the first heat exchange medium flows between the heat transfer plates 11. The flow paths 16 and the second flow paths 17 indicated by chain lines through which the second heat exchange medium flows are alternately formed. One of the first and second heat exchange media is a hot fluid and the other is a cold fluid. The high temperature fluid in the present embodiment is, for example, a fluid having a temperature of 180 ° C. or higher, and more specifically, water vapor or the like.

  As shown in FIG. 3, a gasket groove 19 is formed on one surface 11A of each heat transfer plate 11 by, for example, pressing the groove side surface from the other surface 11B side to the one surface 11A side by press molding. The The gasket 12 is fitted into the gasket groove 19 and attached to one surface 11 </ b> A of the heat transfer plate 11.

  As shown in FIGS. 3 and 4, the gasket 12 includes a core rubber portion 21 that constitutes the gasket body, and first and second canvases 31 and 32 that cover the outer peripheral surface 21 </ b> A of the core rubber portion 21. The The core rubber portion 21 is formed of rubber such as EPDM (ethylene propylene diene rubber), H-NBR (hydrogenated nitrile rubber), NBR (nitrile rubber), and is preferably formed of EPDM.

  The center rubber portion 21 has a hexagonal cross section that is flattened so as to be long in the width direction D of the gasket 12. The hexagon has two sides 22A and 22D that are substantially parallel to the width direction D and are opposed to each other, two sides 22B and 22C that are connected to the side 22A so that the inner angle forms an obtuse angle, and the inner angle to the side 22D. Is composed of two sides 22E and 22F connected so as to form an obtuse angle.

  The first canvas 31 covers the outer peripheral surface 21A of the three sides 22A to 22C, and the second canvas 32 covers the outer peripheral surface 21A of the three sides 22D to 22F. Both ends 31E and 31F in the width direction D of the first canvas 31 are respectively in the width direction of the second canvas 32 at the vertex 21G that is the intersection of the sides 22B and 22E and the vertex 21H that is the intersection of the sides 22C and 22F. Are connected to both ends 32E and 32F. Thereby, as for the center rubber part 21, the perimeter of 21 A of outer peripheral surfaces is coat | covered with a canvas. Note that the end portions 31E, 31F, 32E, and 32F of the first and second canvases 31 and 32 protrude outward from the outer peripheral surface 21A of the core rubber portion 21, as shown in FIG. The parts are bonded to each other by, for example, rubber paste impregnated in canvas as described later.

  As shown in FIG. 3, the gasket groove 19 provided on one surface 11 </ b> A of the heat transfer plate 11 has a trapezoidal shape, and the inner peripheral surface 19 </ b> A of the gasket groove 19 is a first covering the three sides 22 </ b> A to 22 </ b> C. The shape along the outer peripheral surface of the canvas 31 is exhibited.

  The outer peripheral surface of the first canvas 31 covering the three sides 22A to 22C is in close contact with the inner peripheral surface 19A of the groove 19 provided in one of the two adjacent heat transfer plates 11, 11. . The portion covering the side 22 </ b> D of the second canvas 32 is in close contact with the other surface 11 </ b> B of the other heat transfer plate 11. The gasket 12 is compressed in the thickness direction by the pair of heat transfer plates 11, 11, and a flow path (the first flow path 16 or the second flow path 17) formed between the two heat transfer plates 11 is Sealed by such a gasket 12.

  The first and second canvases 31 and 32 may be impregnated with rubber glue before being bonded to the core rubber part 21. The rubber paste is obtained by diluting a rubber material such as EPDM, SBR (styrene butadiene rubber), urethane rubber, H-NBR, NBR, fluorine rubber, silicon rubber with a general organic solvent such as toluene. The concentration is about 10 to 30% by mass. The rubber paste impregnation treatment is a treatment in which, for example, the first and second canvases 31 and 32 are immersed in rubber paste and then dried by heating, so that a rubber paste film is substantially formed on both surfaces thereof. is there. The first and second canvases 31 and 32 are easily bonded to the core rubber portion 21 by being impregnated with rubber paste, and the ends of the canvas (for example, 31E and 32E) are also bonded to each other. It becomes easy to be done.

  Further, the first and second canvases 31 and 32 may be coated with a coating agent. The coating agent is, for example, a product obtained by diluting fluorine rubber, silicon rubber or the like with a general organic solvent such as toluene. In the coating process, for example, the coating agent is appropriately coated on one surface of the first and second canvases 31 and 32 (the surface constituting the outer peripheral surface of the gasket) by a known coating method and then dried by heating. This is a process for forming a coating film on the one surface. At this time, it is preferable that the coating agent is coated so as not to penetrate to the other surfaces of the first and second canvases 31 and 32 (surfaces that adhere to the core rubber portion 21). This is because the coating agent does not permeate to the other surface, so that the adhesion between the canvas and the core rubber portion is not hindered. In the present embodiment, the heat resistance and chemical resistance of the gasket can be further improved by the coating agent treatment. Note that the coating treatment and the rubber paste impregnation treatment may be used in combination, or only one of them may be used.

  As shown in FIG. 3, each of the first and second canvases 31 and 32 is arranged along the warp yarn (first yarn) 33 arranged along the longitudinal direction L of the gasket and the width direction D of the gasket. It is a woven fabric woven with the weft yarn (second yarn) 34 to be made. The warp yarn 33 is a non-stretchable yarn that does not have stretchability, and is, for example, a twisted yarn formed by twisting filaments such as aramid, nylon, and polyester. The weft 34 is a crimped yarn made of a fiber such as polyester or nylon, and is a stretchable yarn having stretchability. Thereby, the 1st and 2nd canvases 31 and 32 have elasticity in the width direction D of a gasket. However, both the warp yarn 33 and the weft yarn 34 may be non-stretchable yarns.

  The thickness of the first and second canvases 31 and 32 is, for example, 0.3 mm to 0.8 mm. The thickness of the canvas is the thickness of the canvas before being impregnated before being bonded to the core rubber part 21 and before the impregnation, and measured in accordance with JIS L 1096 It is.

Next, an example of a method for manufacturing the gasket 12 according to the present embodiment will be described.
In the present embodiment, first, if desired, the first and second canvases 31 and 32 are subjected to the rubber paste impregnation treatment described above and / or the coating treatment with a coating agent, and the core rubber portion 21 is configured. An unvulcanized rubber having a flat hexagonal cross section is prepared. Next, after covering the first and second canvases 31 and 32 on the outer peripheral surfaces of the unvulcanized rubber corresponding to the three sides 22A to 22C and 22D to 22F, respectively, the gaskets 12 are formed by press molding. And heating in a thickness direction (perpendicular to the outer peripheral surface 21A of the sides 22A and 22D). The unvulcanized rubber is vulcanized by this press molding, and the first and second canvases 31 and 32 are vulcanized and bonded to the core rubber part 21, and the canvas ends 31E and 32E (or 31F and 32F). ) Are bonded together to obtain the gasket 12. Note that the bonded end portions 31E and 32E (or 31F and 32F) protrude from the outer peripheral surface of the core rubber portion 21, but when the protruding portion is too long, the portions are appropriately cut. May be.

  As described above, in this embodiment, since the gasket is composed of a composite material of rubber and canvas, the gasket can be reinforced without impairing the flexibility of the gasket. Therefore, even when the gasket is used so as to be in contact with a high-temperature fluid of, for example, 180 ° C. or higher, permanent deformation of the gasket is suppressed and cracking is hardly generated, and the durability of the gasket can be improved.

  Furthermore, in this embodiment, as shown in FIG. 4, the outer peripheral surfaces 21A of the sides (22A to 22C) covered with the first canvas 31 are all directed downward (one along the thickness direction of the gasket), and the second The outer peripheral surfaces 21A of the sides (22D to 22F) covered with the canvas 32 are all directed upward (the other along the thickness direction). Accordingly, the first and second canvases 21 and 22 are easily pressed from above and below in the thickness direction and easily adhered to the core rubber 21. Further, when the first yarn is a non-stretchable yarn and the second yarn is a stretchable yarn, the canvas has stretchability in the width direction D, which is easily deformed when the gasket is compressed by the heat transfer plate, and non-stretching. Since the strength of the gasket is secured by the stretchable yarn, permanent deformation of the gasket can be further suppressed.

  FIG. 5 is a cross-sectional view showing a gasket according to a second embodiment of the present invention. In the present embodiment, the core rubber portion 21 is an octagonal cross section that is flattened so as to be longer in the width direction D instead of a hexagonal cross section. In this octagon, two sides 40A and 40F that are substantially parallel to each other, and two sides 40B and 40C that are connected so that the inner angle forms an obtuse angle with the side 40A, and the inner angle forms an obtuse angle with the side 40F. It has two sides 40G and 40H to be connected, and further has a side 40D between the sides 40B and 40G, and a side 40E between the sides 40C and 40H. Note that the sides 40D and 40E are inclined at an obtuse angle with respect to the first side 40A, similarly to the sides 40B and 40C.

  In the present embodiment, the first canvas 31 covers the outer peripheral surface 21A of the five sides 40A to 40E, and the second canvas 32 covers the outer peripheral surface 21A of the three sides 40F to 40H. Then, both ends 31E and 31F of the first canvas 31 are respectively the two ends 32E and 32F of the second canvas 32 at the vertex 41A that is the intersection of the sides 40D and 40G and the vertex 41B that is the intersection of the sides 40E and 40H. Each is connected in the same manner as in the first embodiment. Also in the present embodiment, as shown in FIG. 5, the outer peripheral surfaces 21A of the sides 40A to 40E covered with the first canvas 31 are all directed downward, and the outer periphery of the sides 40F to 40H covered with the second canvas 32 Since all the surfaces 21A face upward, as in the first embodiment, pressing the canvas in the thickness direction makes it easier to bond the canvas to the core rubber portion 21.

  FIG. 6 is a cross-sectional view showing a gasket according to a third embodiment of the present invention. In the first embodiment, the cross-sectional shape of the core rubber portion 21 is a convex hexagon. However, in this embodiment, the cross-sectional shape of the core rubber portion 21 is a concave hexagon as shown in FIG. This is different from the first embodiment. That is, in this embodiment, the sides 22B and 22C are connected to the side 22A so that the inner angle forms an acute angle, and the sides 22E and 22F are connected to the side 22D so that the inner angle forms an acute angle.

  In the present invention, the cross-sectional shape of the core rubber portion 21 may be a convex polygon or a concave polygon other than a hexagon or an octagon. Moreover, the shape of the gasket 12 may not be a polygon, for example, may have a curved surface. For example, as shown in FIG. 7, the outer peripheral surface 21A has a pair of parallel planes 50A and 50B that are substantially parallel to the width direction D and face each other, and a pair of cross-sectional arcs that face each other and bulge outward. (Cross section curve) curved surfaces 50C and 50D may be used. In this case, as in the first and second embodiments, the first canvas 31 is a portion facing the lower side of the outer peripheral surface 21A, and the second canvas 32 is a portion facing the upper side of the outer peripheral surface 21A. Coated. Further, as shown in FIG. 8, the curved surfaces 50C and 50D having a cross-sectional arc shape (cross-sectional curve) may swell inward. Further, as shown in FIG. 9, a pair of curved surfaces 51A and 51B having a cross-sectional arc shape (cross-sectional curve) facing each other and bulging inward, and a pair of cross-sectional arc shapes facing each other and bulging inward ( (Curve-shaped curve) 51C and 51D. The canvas ends 31E and 32E (or 31F and 32F) may protrude as shown in FIG. 7, or may not protrude as shown in FIGS.

  Embodiments of the present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[Example 1]
A shape as shown in FIG. 4 is formed by press-molding an outer peripheral surface of a non-vulcanized rubber having a flat hexagonal cross section formed from EPDM and covering the first and second canvases having a thickness of 0.45 mm. A gasket having a length of 100 mm, a width of 9.5 mm, and a thickness of 3.8 mm was manufactured. The first and second canvases are plain woven fabrics woven from warp yarns and weft yarns. The warp yarns are arranged in the longitudinal direction of the gasket and the weft yarns are arranged in the width direction of the gasket. Further, as the warp and weft of the first and second canvases, non-stretchable yarns of nylon 6 filaments having a fineness of 470 dtex and a twist number of 120 T / m were used.

[Comparative Example 1]
This was carried out in the same manner as in Example 1 except that the unvulcanized rubber was formed from fluororubber and the outer peripheral surface of the core rubber part was not covered with the canvas.

[Comparative Example 2]
The same operation as in Example 1 was performed except that the outer peripheral surface of the core rubber part was not covered with the canvas.

[Evaluation methods]
The compression set rate of each of the gaskets of Examples and Comparative Examples was measured based on JIS K6262. Specifically, each gasket is sandwiched between two metal plates in a compression device and compressed in the thickness direction at a pressure of 40 N · m, in a dry heat environment with a temperature of 190 ° C. and a humidity of 0%, and at 190 ° C. Each was left in a humid heat environment (under a saturated water vapor pressure of 190 ° C.) for 500 hours. And the compression set rate of the gasket was calculated from the change in the thickness of the gasket before and after being left as indicated by the following formula. Further, the appearance after the standing was visually observed. The evaluation results are shown in Table 1.
CS = (T ₀ −T ₂ ) / (T ₀ −T ₁ ) × 100
CS: compression set (%), T ₀ : original thickness of the gasket (mm), T ₁ : spacer thickness (= 2.69 mm), T ₂ : removed from the compression device, 30 minutes later Gasket thickness (mm)

DESCRIPTION OF SYMBOLS 10 Plate type heat exchanger 11 Heat transfer plate 12 Gasket 21 Core rubber part 31 1st canvas 32 2nd canvas 33 Warp yarn (1st yarn)
34 Weft thread (second thread)

Claims (8)

  A gasket for sealing a flow path formed between heat transfer plates of a plate-type heat exchanger, comprising: a core rubber portion formed of rubber; and a canvas covering an outer peripheral surface of the core rubber portion. A gasket characterized by that.   The gasket has first and second canvases covering the outer peripheral surface of the core rubber portion, the core rubber portion has a polygonal cross section, and the outer peripheral surface of the core rubber portion is: 2. The gasket according to claim 1, wherein at least one side of the polygon is covered with the first canvas, and the remaining side of the polygon is covered with the second canvas.   The gasket according to claim 2, wherein both ends of the first canvas are respectively connected to both ends of the second canvas at the apex of the polygon.   The gasket according to claim 1, wherein at least a part of the canvas is made of elastic yarn and has elasticity.   The gasket according to claim 4, wherein the canvas has elasticity in a width direction of the gasket.   The canvas is a woven fabric woven from a first yarn arranged along the longitudinal direction of the gasket and a second yarn arranged along the width direction of the gasket, and the first yarn is 6. The gasket according to claim 5, wherein the gasket is a non-stretchable yarn and the second yarn is a stretchable yarn.   2. The gasket according to claim 1, wherein the entire inner peripheral surface of the core rubber portion is covered with a canvas.   The gasket according to claim 1, wherein the canvas is impregnated with rubber glue or coated with a coating agent.

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