Plate heat exchanger

Abstract

A flow-path forming gasket is interposed between peripheries of each adjacent ones of stacked heat transfer plates; communicating-path forming gaskets are each installed, surrounding the passage holes in each adjacent ones of the heat transfer plates alternately; and thereby a first flow path adapted to pass a high-temperature fluid, a second flow path adapted to pass a low-temperature fluid, and communicating paths adapted to cause the fluids, respectively, to flow in and out of the first and second flow paths are formed alternately on opposite sides of each heat transfer plate. A drain hole is formed in each of the heat transfer plates to discharge fluid leaking from the first flow path, the second flow path, or the communicating path. The drain hole is surrounded by gaskets isolated from the first flow path, the second flow path, or the communicating path. A leakage flow path or a leakage collector is formed by the gaskets.

Claims

1. A plate heat exchanger wherein: a plurality of heat transfer plates are stacked, each being provided with a plurality of passage holes; a flow-path forming gasket is interposed between peripheries of each adjacent ones of the plurality of heat transfer plates, thereby alternately forming a first flow path adapted to pass a high-temperature fluid and a second flow path adapted to pass a low-temperature fluid on opposite sides of each heat transfer plate; communicating-path forming gaskets surrounding the passage holes are each interposed between each adjacent ones of the plurality of heat transfer plates, thereby forming a communicating path adapted to cause a fluid to flow in and out of the first flow path and a communicating path adapted to cause a fluid to flow in and out the second flow path; a drain hole is formed in each of the heat transfer plates to discharge fluid leaking from the first flow path, the second flow path, or the communicating path; and the drain hole is isolated from the first flow path, the second flow path, or the communicating path by a plurality of gaskets, forming a leakage flow path or a leakage collector, and an entire circumference of a first flow-path forming gasket which forms the first flow path is surrounded by a peripheral gasket; and the leakage flow path is formed between the first flow-path forming gasket and the peripheral gasket.

2. The plate heat exchanger according to claim 1, wherein each of the communicating-path forming gaskets is a double-line gasket made up of an inner gasket member and an outer gasket member; the drain hole is formed between the inner gasket member and the outer gasket member; the leakage flow path is provided between the inner gasket member and the outer gasket member; and the drain holes exposed to the first flow path or the second flow path by being located next to the leakage flow path are communicated together by an annular gasket.

3. The plate heat exchanger according to claim 1, wherein the passage holes are formed in respective corners of the heat transfer plate.

4. A plate heat exchanger wherein: a plurality of heat transfer plates are stacked, each being provided with a plurality of passage holes; a flow-path forming gasket is interposed between peripheries of each adjacent ones of the plurality of heat transfer plates, thereby alternately forming a first flow path adapted to pass a high-temperature fluid and a second flow path adapted to pass a low-temperature fluid on opposite sides of each heat transfer plate; communicating-path forming gaskets surrounding the passage holes are each interposed between each adjacent ones of the plurality of heat transfer plates, thereby forming a communicating path adapted to cause a fluid to flow in and out of the first flow path and a communicating path adapted to cause a fluid to flow in and out the second flow path; a drain hole is formed in each of the heat transfer plates to discharge fluid leaking from the first flow path, the second flow path, or the communicating path; and the drain hole is isolated from the first flow path, the second flow path, or the communicating path by a plurality of gaskets, forming a leakage flow path or a leakage collector, and a fluid supply hole is formed in the heat transfer plate to supply a third fluid into the leakage flow path or the leakage collector.

5. The plate heat exchanger according to claim 4, wherein respective communicating-path forming gaskets are enclosed by a second flow-path forming gasket adapted to form the second flow path and a local gasket; and the leakage collector is formed among the respective communicating-path forming gaskets, the second flow-path forming gasket, and the local gasket.

6. A plate heat exchanger wherein: a plurality of heat transfer plates are stacked, each being provided with a plurality of passage holes; a flow-path forming gasket is interposed between peripheries of each adjacent ones of the plurality of heat transfer plates, thereby alternately forming a first flow path adapted to pass a high-temperature fluid and a second flow path adapted to pass a low-temperature fluid on opposite sides of each heat transfer plate; communicating-path forming gaskets surrounding the passage holes are each interposed between each adjacent ones of the plurality of heat transfer plates, thereby forming a communicating path adapted to cause a fluid to flow in and out of the first flow path and a communicating path adapted to cause a fluid to flow in and out the second flow path; a drain hole is formed in each of the heat transfer plates to discharge fluid leaking from the first flow path, the second flow path, or the communicating path; and the drain hole is isolated from the first flow path, the second flow path, or the communicating path by a plurality of gaskets, forming a leakage flow path or a leakage collector, and a drain channel continuous with the drain hole is formed in one of a fixed frame and a movable frame which sandwich the plurality of stacked heat transfer plates; a drain nozzle is mounted on the drain channel; and a sensor adapted to detect a fluid is connected to the drain nozzle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic exploded perspective view showing principal part of a plate heat exchanger according to a first embodiment of the present invention.

(2) FIG. 2 is a schematic perspective view showing the plate heat exchanger according to the first embodiment of the present invention.

(3) FIG. 3 is a schematic exploded perspective view showing principal part of the plate heat exchanger according to a second embodiment of the present invention.

(4) FIG. 4 is a schematic exploded perspective view showing principal part of the plate heat exchanger according to a third embodiment of the present invention.

(5) FIG. 5A is an enlarged plan view showing principal part in the upper left of the plate heat exchanger according to the third embodiment of the present invention.

(6) FIG. 5B is an enlarged sectional view of the plate heat exchanger according to the third embodiment of the present invention taken along line V-V in FIG. 5A.

(7) FIG. 5C is an enlarged sectional view of the plate heat exchanger according to the third embodiment of the present invention taken along line V-V in FIG. 5A.

(8) FIG. 6A is an enlarged plan view showing principal part in the lower left of the plate heat exchanger according to the third embodiment of the present invention.

(9) FIG. 6B is an enlarged sectional view of the plate heat exchanger according to the third embodiment of the present invention taken along line VI-VI in FIG. 6A.

(10) FIG. 6C is an enlarged sectional view of the plate heat exchanger according to the third embodiment of the present invention taken along line VI-VI in FIG. 6A.

(11) FIG. 7 is a schematic exploded perspective view showing principal part of the plate heat exchanger according to a fourth embodiment of the present invention.

(12) FIG. 8 is a schematic perspective view showing a conventional plate heat exchanger.

(13) FIG. 9 is a schematic exploded perspective view showing the conventional plate heat exchanger.

DESCRIPTION OF EMBODIMENTS

First Embodiment

(14) A plate heat exchanger according to a first embodiment of the present invention is described below with reference to FIGS. 1 and 2. The same components as in conventional components are denoted by the same reference numerals as the corresponding conventional components. In the following description, positional terms such as upper, lower, right, and left are exemplary in each embodiment, and, needless to say, may represent different positions depending on actual usage.

(15) As is conventionally the case, the plate heat exchanger according to the first embodiment is an apparatus in which a first flow path 1 and a second flow path 2 are formed alternately between heat transfer plates 20 as shown in FIG. 1, and a high-temperature fluid H is passed through the first flow path 1 while a low-temperature fluid C is passed through the second flow path 2. That is, the first flow path 1 adapted to pass the high-temperature fluid H and the second flow path 2 adapted to pass the low-temperature fluid C are formed alternately on opposite sides of each heat transfer plate 20.

(16) The first flow path 1 is formed by a first flow-path forming gasket 31a which surrounds upper and lower left passage holes 21 and 22 and a heat transfer portion (trapezoidal shape in figures) of the heat transfer plate 20. Then, low-temperature-fluid communicating paths 3c are formed by low-temperature-fluid communicating-path forming gaskets 32c which surround upper and lower right passage holes 23 and 24 of the heat transfer plate 20, respectively.

(17) As the low-temperature-fluid communicating-path forming gaskets 32c are interposed between the heat transfer plates 20 which form the first flow path 1, the low-temperature fluid C is supplied into the second flow path 2 from below without flowing between the heat transfer plates 20 which form the first flow path 1 and discharged from an upper side of the second flow path 2.

(18) An entire circumference of the first flow-path forming gasket 31a as well as the two low-temperature-fluid communicating-path forming gaskets 32c are surrounded by a peripheral gasket 33 interposed along an outer peripheral edges of the heat transfer plate 20, and a leakage flow path 4 is provided between the peripheral gasket 33 and a set of gaskets made up of the first flow-path forming gasket 31a and the two low-temperature-fluid communicating-path forming gaskets 32c.

(19) The second flow path 2 is formed by a second flow-path forming gasket 31b which surrounds the upper and lower right passage holes 23 and 24 and the heat transfer portion (trapezoidal shape in figures) of the heat transfer plate 20 adjacent to the aforesaid heat transfer plate 20. Also, high-temperature-fluid communicating paths 3h are formed by high-temperature-fluid communicating-path forming gaskets 32h which surround the upper and lower left passage holes 21 and 22 of this heat transfer plate 20, respectively.

(20) As the high-temperature-fluid communicating-path forming gaskets 32h are interposed between the heat transfer plates 20 which form the second flow path 2, the high-temperature fluid H is supplied into the first flow path 1 from above without flowing between the heat transfer plates 20 which form the second flow path 2 and discharged from a lower side of the first flow path 1.

(21) The high-temperature-fluid communicating-path forming gaskets 32h are surrounded by a local gasket 34 and part of the second flow-path forming gasket 31b (that portion which is inclined in close vicinity to the high-temperature-fluid communicating-path forming gaskets 32h, in figures) and first and second leakage collectors 5a and 5b (triangular shape in figures) are provided among the gaskets 32h, 34, and 31b to collect high-temperature fluid Hm leaking from the high-temperature-fluid communicating-path forming gaskets 32h.

(22) Also, a drain hole (hereinafter referred to as a “first drain hole”) 6a is formed in lower end part of the first leakage collector 5a by penetrating the heat transfer plate 20 in order for the high-temperature fluid Hm leaking into the first leakage collector 5a to be discharged into the leakage flow path 4.

(23) Besides, a drain hole (hereinafter referred to as a “second drain hole”) 6b is formed in lower end part of the leakage flow path 4 in order for the high-temperature fluid Hm flowing down in the leakage flow path 4 to be discharged therethrough. By penetrating the heat transfer plate 20, the second drain hole 6b is communicated with the leakage flow path 4 and the second leakage collector 5b placed next to each other via the heat transfer plate 20.

(24) Therefore, the second drain hole 6b is continuous among adjacent heat transfer plates 20. Also, a drain channel (not numbered) through which the leaking high-temperature fluid Hm flows is installed such that the second drain hole 6b is made to be continuous. Also, a drain hole (not shown) continuous with the drain channel is formed on the fixed frame 11 and a drain nozzle 8 is mounted in the drain hole as shown in FIG. 2.

(25) Sensors (not shown) adapted to detect the temperature, pressure, leakage amount, liquid components, and the like of the leaking high-temperature fluid Hm are mounted on the drain nozzle 8 according to needs and circumstances. Sensors adapted to convert the temperature or the like into electrical signals may be used for that, and a system adapted to send the electrical signals may be constructed in an administration office.

(26) Furthermore, in the first leakage collector 5a, a third fluid supply hole 7 communicated with the leakage flow path 4 is formed by penetrating the heat transfer plate 20. The third fluid supply hole 7 is formed in a portion where the leakage flow path 4 formed between the adjacent heat transfer plates 20 overlaps the first leakage collector 5a, i.e., in upper part of the heat transfer plates 20. A third fluid supply hole (not shown) is formed also in the fixed frame 11, and a third fluid supply nozzle 9 is mounted in the third fluid supply hole 7 as shown in FIG. 2.

(27) An inert gas such as nitrogen or a fluid such as pure water is supplied from the third fluid supply nozzle 9 into the leakage flow path 4 and the first and second leakage collectors 5a and 5b through the third fluid supply hole 7 to expel oxygen from the air initially existing in this space and thereby protect entire areas of the gaskets 31a, 32h, and 32c and inner sides of the gaskets 31b, 33, and 34 from oxidation. The third fluid supply hole 7 is formed at such a location as to be used as the second drain hole 6b when the heat transfer plate 20 is assembled upside down.

(28) With the first and second drain holes 6a and 6b formed in the heat transfer plates 20 and with the first and second leakage collectors 5a and 5b provided in this way, the plate heat exchanger according to the first embodiment also exchanges heat between the high-temperature fluid H flowing through the first flow paths 1 and the low-temperature fluid C flowing through the second flow paths 2.

(29) Then, when any of the first flow paths 1 and the high-temperature-fluid communicating-path forming gaskets 32h in contact with the high-temperature fluid H degrade in a thermal load environment, the plate heat exchanger according to the first embodiment enables ease of determination through detection of the leaking high-temperature fluid Hm, that leakage of the high-temperature fluid Hm has occurred.

(30) That is, when any of the first flow-path forming gaskets 31a degrades, the high-temperature fluid Hm leaks out of the first flow-path forming gasket 31a into the leakage flow path 4. Also, when any of the high-temperature-fluid communicating-path forming gaskets 32h degrades, the leaking high-temperature fluid Hm leaks out of the high-temperature-fluid communicating path 3h into the leakage flow path 4 through the first drain hole 6a formed in the first leakage collector 5a.

(31) Then, the high-temperature fluid Hm leaking out into the leakage flow path 4 passes through the second drain hole 6b and the drain channel and is discharged through the drain nozzle 8. Therefore, by detecting that the high-temperature fluid Hm is being discharged through the drain nozzle 8, it is possible to determine that leakage of the high-temperature fluid Hm has occurred due to degradation of the first flow-path forming gasket 31a or the high-temperature-fluid communicating-path forming gasket 32h.

(32) Note that when pure water is constantly supplied from the third fluid supply nozzle 9, the pure water is discharged constantly through the drain nozzle 8. Pure water and leaking high-temperature fluid Hm can be distinguished by a sensor, and thus by detecting that high-temperature fluid Hm is being discharged through the drain nozzle 8, it is possible to determine that leakage of the high-temperature fluid Hm has occurred due to degradation of the first flow-path forming gasket 31a or the high-temperature-fluid communicating-path forming gasket 32h.

Second Embodiment

(33) Next, a plate heat exchanger according to a second embodiment of the present invention is described with reference to FIG. 3. The same components as in the first embodiment are denoted by the same reference numerals as the corresponding components of the first embodiment.

(34) As with the first embodiment, the plate heat exchanger according to the second embodiment is configured such that the peripheral gasket 33 is interposed along the outer peripheral edges of each heat transfer plate 20. The peripheral gasket 33 surrounds the entire circumference of the first flow-path forming gasket 31a as well as the two low-temperature-fluid communicating-path forming gaskets 32c, and the leakage flow path 4 is not only provided, but also installed by surrounding the entire circumference of the second flow-path forming gasket 31b as well as the two high-temperature-fluid communicating-path forming gaskets 32h.

(35) That is, in the plate heat exchanger according to the second embodiment, the second flow-path forming gasket 31b surrounds (trapezoidally in figures) the upper and lower right passage holes 23 and 24 and heat transfer portion of the heat transfer plate 20, forming the second flow path 2. Also, the high-temperature-fluid communicating-path forming gaskets 32h surround the upper and lower left passage holes 21 and 22, thereby forming the high-temperature-fluid communicating paths 3h. Then, the leakage flow path 4 is provided between the peripheral gasket 33 and a set of gaskets made up of the second flow-path forming gasket 31b and the two high-temperature-fluid communicating-path forming gaskets 32h.

(36) Thus, in the second embodiment, first and second leakage collectors 5a and 5b such as those of the first embodiment are not provided, the first flow-path forming gasket 31a and the second flow-path forming gasket 31b are shaped to be bilaterally symmetrical, and the low-temperature-fluid communicating-path forming gaskets 32c and the high-temperature-fluid communicating-path forming gaskets 32h are interposed bilaterally symmetrically.

(37) However, in the second embodiment, as with the first embodiment, drain holes 6 are formed in the lower part of the leakage flow path 4, penetrating the heat transfer plate 20, and the third fluid supply holes 7 are formed in the upper part of the leakage flow path 4, penetrating the heat transfer plate 20. Plural drain holes 6 and plural third fluid supply holes 7 can be formed in desired locations of the leakage flow path 4, but preferably the drain holes 6 and the third fluid supply holes 7 are formed vertically symmetrically with respect to a horizontal center axis serving as an axis of symmetry such that the drain holes 6 and third fluid supply holes 7 can be interchanged when the heat transfer plate 20 is assembled upside down.

(38) Also, between each adjacent heat transfer plates 20, the drain holes 6 make up a drain channel (not numbered) through which the leaking high-temperature fluid Hm flows. Also, between each adjacent heat transfer plates 20, the third fluid supply holes 7 make up a third fluid supply path (not numbered) through which the leaking high-temperature fluid Hm flows.

(39) Although not illustrated, as with the first embodiment, drain holes and third fluid supply holes continuous with the drain channel and the third fluid supply path respectively are formed also in the fixed frame 11 and the drain nozzles and the third fluid supply nozzles are mounted in the drain holes and the third fluid supply holes, respectively. Even if plural drain holes and plural third fluid supply holes are formed, a single drain nozzle and a single third fluid supply nozzle may be mounted.

(40) The plate heat exchanger according to the second embodiment also exchanges heat between the high-temperature fluid H flowing through the first flow paths 1 and the low-temperature fluid C flowing through the second flow paths 2. Then, when the first flow-path forming gaskets 31a and the high-temperature-fluid communicating-path forming gaskets 32h in contact with the high-temperature fluid H degrade in a thermal load environment, it is possible to easily determine, by detecting the leaking high-temperature fluid Hm, that leakage of the high-temperature fluid Hm has occurred.

(41) That is, when the first flow-path forming gaskets 31a and the high-temperature-fluid communicating-path forming gaskets 32h degrade by being placed in contact with the high-temperature fluid H, the high-temperature fluid Hm flows down into the leakage flow path 4 from the first flow-path forming gaskets 31a and the high-temperature-fluid communicating-path forming gaskets 32h, and then the leaking high-temperature fluid Hm is discharged through the drain nozzle after passing through the drain holes 6 and the drain channel. By detecting the discharged high-temperature fluid Hm, it is possible to determine that leakage of the high-temperature fluid Hm has occurred due to degradation of the first flow-path forming gaskets 31a and the high-temperature-fluid communicating-path forming gaskets 32h.

(42) An inert gas such as nitrogen or pure water is supplied from supply nozzles to expel the air initially existing in the leakage flow path 4 and thereby protect the gaskets 31a, 31b, 32a, 32c, 32h, and 33 from oxidation. Even if pure water is supplied constantly, the leaking high-temperature fluid Hm flowing out through the drain holes 6 can be identified and detected by a sensor.

Third Embodiment

(43) Next, a plate heat exchanger according to a third embodiment of the present invention is described below with reference to FIGS. 4 to 6. The same components as in the first and second embodiments are denoted by the same reference numerals as the corresponding components of the first and second embodiments. FIGS. 5B and 5C show how the passage hole 21 is surrounded by double D gaskets 41 and 42 interposed between the fixed frame 11 and a D plate 20d while FIGS. 6B and 6C show how the passage hole 22 is surrounded by the double D gaskets 41 and 42 interposed between the fixed frame 11 and a D plate 20d as well.

(44) In the plate heat exchanger according to the third embodiment, as with the plate heat exchanger according to the second embodiment, the peripheral gasket 33 interposed along outer peripheries of each heat transfer plates 20 surrounds the first flow-path forming gasket 31a and the two low-temperature-fluid communicating-path forming gaskets 32c, while the peripheral gasket 33 interposed between each adjacent ones of the heat transfer plates 20 surrounds the second flow-path forming gasket 31b and the two high-temperature-fluid communicating-path forming gaskets 32h.

(45) According to the third embodiment, both the low-temperature-fluid communicating-path forming gasket 32c and the high-temperature-fluid communicating-path forming gasket 32h are double-line gaskets made up of an inner gasket member 32c′ or 32h′ and an outer gasket member 32c″ or 32h′ and a low-temperature fluid drain hole 5c and a high-temperature fluid drain hole 5h are formed between each pair of the gasket members 32c′ and 32c″ and between each pair of the gasket members 32h′ and 32h,″ respectively, penetrating the heat transfer plate 20. The low-temperature fluid drain holes 5c and the high-temperature fluid drain holes 5h are formed below the passage holes 21 to 24.

(46) Therefore, to keep the low-temperature fluid drain holes 5c from being exposed in the second flow path 2, the low-temperature fluid drain holes 5c are communicated together by annular gaskets 35c interposed between the heat transfer plates 20 which form the second flow path 2. Also, to keep the high-temperature fluid drain holes 5h from being exposed in the first flow path 1, the high-temperature fluid drain holes 5h are communicated together by annular gaskets 35h interposed between the heat transfer plates 20 which form the first flow path 1.

(47) Then, a high-temperature fluid leak detection drain hole 5d and a low-temperature fluid leak detection drain hole 5e are formed below the leakage flow path 4 formed inside the peripheral gasket 33. As shown in FIG. 6, the high-temperature fluid leak detection drain hole 5d is placed adjacent to the high-temperature fluid drain hole 5h with a lower part of the first flow-path forming gasket 31a or a lower part of the outer gasket member 32h″ therebetween. Also, the low-temperature fluid leak detection drain hole 5e is placed adjacent to the low-temperature fluid drain hole 5c with a lower part of the second flow-path forming gasket 31b or a lower part of the outer gasket member 32c″ therebetween.

(48) In the plate heat exchanger, the drain holes 5h are communicated together by the annular gaskets 35h while the drain holes 5c are communicated together by the annular gaskets 35c. That is, while being sandwiched between the adjacent heat transfer plates 20, the annular gaskets 35h and 35c isolate the drain holes 5h and 5c, respectively, from the first flow paths 1 and the second flow paths 2.

(49) Each of the drain holes 5c, 5h, 5d, and 5e forms a drain channel 5v by means of the annular gasket 35c or 35h interposed between the adjacent heat transfer plates 20. The drain nozzles 8 continuous with the respective drain channels 5v are mounted on the fixed frame 11. A sensor may be mounted also on each drain nozzle 8 although not illustrated.

(50) The plate heat exchanger according to the third embodiment configured as described above also exchanges heat between the high-temperature fluid H flowing through the first flow paths 1 and the low-temperature fluid C flowing through the second flow paths 2. Then, when the first flow-path forming gaskets 31a and the high-temperature-fluid communicating-path forming gaskets 32h in contact with the high-temperature fluid H degrade in a thermal load environment, it is possible to easily determine, by detecting the leaking high-temperature fluid Hm, that leakage of the high-temperature fluid Hm has occurred.

(51) For example, if any of the first flow-path forming gaskets 31a degrades and the high-temperature fluid Hm leaks out of the first flow path 1 into the leakage flow path 4 as shown in FIG. 4, the leaking high-temperature fluid Hm is discharged through the drain nozzle 8 after passing through the high-temperature fluid leak detection drain hole 5d. The leaking high-temperature fluid Hm does not flow into the low-temperature fluid leak detection drain hole 5e surrounded by an annular gasket 35e, and thus by detecting the high-temperature fluid Hm flowing out of the drain nozzle 8, it is possible to determine that leakage of the high-temperature fluid Hm has occurred due to degradation of the first flow-path forming gasket 31a.

(52) Also, if the inner gasket member 32h′ of the high-temperature-fluid communicating-path forming gasket 32h degrades as shown in FIG. 5C or if the annular gasket 35h surrounding the high-temperature fluid drain hole 5h degrades as shown in FIG. 5B, causing the high-temperature fluid Hm to leak, the leaking high-temperature fluid Hm is discharged through the drain nozzle 8.

(53) Also, if the annular gasket 35h or the inner gasket member 32h′ of the high-temperature-fluid communicating-path forming gasket 32h degrades as shown in FIG. 6B or if the first flow-path forming gasket 31a degrades as shown in FIG. 6C, the leaking high-temperature fluid Hm is discharged through the drain nozzle 8, making it possible to determine that leakage of the high-temperature fluid Hm has occurred due to degradation of the annular gasket 35h or the inner gasket member 32h′.

Fourth Embodiment

(54) Next, a plate heat exchanger according to a fourth embodiment of the present invention is described below with reference to FIG. 7. The same components as in the first to third embodiments are denoted by the same reference numerals as the corresponding components of the first to third embodiments.

(55) In the plate heat exchanger according to the fourth embodiment, the passage holes 21 to 24 are arranged generally in a line (or maybe exactly in a line) in the upper and lower direction. The first flow path 1 adapted to pass the high-temperature fluid H is formed by the first flow-path forming gasket 31a which surrounds the two passage holes 21 and 22 on the inner side, but does not surround the two passage holes 23 and 24 on the outer side. On the other hand, the second flow path 2 adapted to pass the low-temperature fluid C is formed by the second flow-path forming gasket 31b which surrounds the four passage holes 21 to 24.

(56) The two outer passage holes 23 and 24 located outside the first flow-path forming gasket 31a are surrounded by the respective low-temperature-fluid communicating-path forming gaskets 32c, thus forming low-temperature-fluid communicating paths 3c. Each of the low-temperature-fluid communicating-path forming gaskets 32c is a double-line gasket made up of the inner gasket member 32c′ surrounding the passage hole 23 or 24 and the outer gasket member 32c″ surrounding the inner gasket member 32c′. The low-temperature-fluid communicating path 3c adapted to pass the low-temperature fluid C is formed in the inner gasket member 32c′ of the low-temperature-fluid communicating-path forming gasket 32c.

(57) Also, the low-temperature fluid leak detection drain hole 5e is formed between the inner gasket member 32c′ and the outer gasket member 32c″, penetrating the heat transfer plate 20. Naturally, the low-temperature fluid leak detection drain hole 5e is formed also in the second flow path 2. In the second flow path 2, adjacent low-temperature fluid leak detection drain holes 5e are communicated together by the annular gasket 35c interposed between the adjacent heat transfer plates 20.

(58) The two inner passage holes 21 and 22 in the second flow path 2 are surrounded by the respective high-temperature-fluid communicating-path forming gaskets 32h, thus forming the high-temperature-fluid communicating paths 3h. Each of the high-temperature-fluid communicating-path forming gaskets 32h is also a double-line gasket made up of the inner gasket member 32h′ surrounding the passage hole 21 or 22 and the outer gasket member 32h″ surrounding the inner gasket member 32h′. The high-temperature-fluid communicating path 3h adapted to pass the high-temperature fluid H is formed in the inner gasket member 32h′ of the high-temperature-fluid communicating-path forming gaskets 32h.

(59) The high-temperature fluid leak detection drain hole 5d is formed between the inner gasket member 32h′ and the outer gasket member 32h″. Naturally, the high-temperature fluid leak detection drain hole 5d is also formed in the first flow path 1. In the first flow path 1, adjacent high-temperature fluid leak detection drain holes 5d are communicated together by the annular gasket 35c.

(60) A communicating hole (not shown) continuous with the low-temperature fluid leak detection drain hole 5e and the high-temperature fluid leak detection drain hole 5d is formed in the fixed frame (not shown) and a drain nozzle (not shown) is mounted in the communicating hole.

(61) The plate heat exchanger according to the fourth embodiment also exchanges heat between the high-temperature fluid H flowing through the first flow paths 1 and the low-temperature fluid C flowing through the second flow paths 2.

(62) When the inner gasket members 32h′ of the high-temperature-fluid communicating-path forming gasket 32h is degraded by the high-temperature fluid H flowing through the high-temperature-fluid communicating path 3h, the high-temperature fluid Hm leaks out of the inner gasket member 32h′, but does not leak into the second flow path 2 because of the outer gasket member 32h″, and the leaking high-temperature fluid Hm is discharged through the drain nozzle by moving through the annular gasket 35c.

(63) Also, when the inner gasket member 32c′ of the low-temperature-fluid communicating-path forming gasket 32c is degraded by the low-temperature fluid C flowing through the low-temperature-fluid communicating path 3c, low-temperature fluid Cm leaks out of the inner gasket member 32c′, but does not leak outside because of the outer gasket member 32c″, and the leaking low-temperature fluid Cm is discharged through the drain nozzle by moving through the annular gasket 35c.

(64) In this way, by detecting that the high-temperature fluid Hm or the low-temperature fluid Cm leaking from the drain nozzle is being discharged, it possible to determine that leakage of the high-temperature fluid Hm or the low-temperature fluid Cm has occurred due to degradation of the inner gasket member 32h′ or 32c′.

(65) Thus, in the plate heat exchanger according to the present embodiment, the plurality of heat transfer plates 20 are stacked, each being provided with the plurality of passage holes 21, 22, 23, and 24; the flow-path forming gasket 31a or 31b is interposed between peripheries of each adjacent ones of the heat transfer plates 20, thereby alternately forming the first flow path 1 adapted to pass the high-temperature fluid H and the second flow path 2 adapted to pass the low-temperature fluid C on opposite sides of each heat transfer plate 20; the communicating-path forming gaskets 32c and 32h surrounding the passage holes 21, 22, 23, and 24 are interposed between adjacent ones of the heat transfer plates 20, thereby forming the communicating path 3 adapted to cause the fluid H to flow in and out of the first flow path 1 and the communicating path 3 adapted to cause the fluid C to flow in and out the second flow path 2; the drain holes 5c, 5e, 5d, 5h, 6, 6a, and 6b are formed in each of the heat transfer plates 20 to discharge fluid Hm or Cm leaking from the first flow path 1, the second flow path 2, or the communicating path 3; and the drain holes 5c, 5e, 5d, 5h, 6, 6a, and 6b are surrounded by the plurality of gaskets 31a, 31b, 32c, 32h, 33, 34, 35c, 35d, 35e, and 35h, thus forming the leakage flow path 4 or the leakage collector 5a or 5b isolated from the first flow path 1, the second flow path 2, or the communicating path 3. Consequently, the leakage flow path 4 or the leakage collector 5a or 5b including the drain holes 5c, 5e, 5d, 5h, 6, 6a, and 6b are formed by the plurality of gaskets 31a, 31b, 32c, 32h, 33, 34, 35c, 35d, 35e, and 35h, and when the first flow-path forming gasket 31a, the second flow-path forming gasket 31b, or the communicating-path forming gasket 32c or 32h degrades in a thermal load environment, causing the fluid H or C to leak from the gasket 31a or 31b of the first flow path 1, the second flow path 2, or the communicating path 3, the fluid H or C flows into the drain holes 5c, 5e, 5d, 5h, 6, 6a, and 6b through the leakage flow path 4 or the leakage collector 5a or 5b and is discharged through the drain holes 5c, 5e, 5d, 5h, 6, 6a, and 6b, making it possible to detect liquid leakage of the high-temperature fluid H due to degradation of the gaskets.

(66) Also, in the plate heat exchanger according to the present embodiment, the leakage flow path 4 is formed between the first flow-path forming gasket 31a and the peripheral gasket 33 which surrounds the entire circumference of the first flow-path forming gasket 31a. This not only allows the leakage flow path 4 to be formed between the peripheral gasket 33 and the first flow-path forming gasket 31a, but also keeps the outer side of the first flow-path forming gasket 31a from contact with the atmosphere by means of the peripheral gasket 33, making the first flow-path forming gasket 31a less prone to degradation.

(67) Also, in the plate heat exchanger according to the present embodiment, the leakage collectors 5a and 5b are formed between the communicating-path forming gaskets 32c and 32h and a set of the second flow-path forming gasket 31b and the local gasket 34 surrounding the communicating-path forming gaskets 32c and 32h. This not only allows the leakage collectors 5a and 5b to be formed by the second flow-path forming gasket 31b and the local gasket 34 which surround the first flow-path forming gasket 31a, but also keeps the outer side of the first flow-path forming gasket 31a from contact with the atmosphere by means of the local gasket 34, making the first flow-path forming gasket 31a less prone to degradation.

(68) Also, in the plate heat exchanger according to the present embodiment, each of the communicating-path forming gaskets 32c and 32h is a double-line gasket made up of the inner gasket member 32c′ or 32h′ and the outer gasket member 32c″ or 32h″; the drain holes 5c, 5e, 5d, 5h, 6, 6a, 6b are formed between the inner gasket member 32c′ or 32h′ and the outer gasket member 32c″ or 32h″; the leakage flow path 4 is provided between the inner gasket member 32c′ or 32h′ and the outer gasket member 32c″ or 32h″; and the drain holes 5c, 5e, 5d, 5h, 6, 6a, 6b exposed to the first flow path 1 or the second flow path 2 by being located next to the leakage flow path 4 are communicated together by the annular gasket 35c, 35d, 35e, or 35h. Since each of the communicating-path forming gaskets 32c and 32h is a double-line gasket made up of the inner gasket member 32c′ or 32h′ and the outer gasket member 32c″ or 32h″, even when fluid leaks out of the inner gasket member 32c′ or 32h′ due to degradation of the inner gasket member 32c′ or 32h′, fluid does not leak out of the outer gasket member 32c″ or 32h″, and can be discharged to the leakage flow path 4 through the drain holes 5c, 5e, 5d, 5h, 6, 6a, 6b. Since the drain holes 5c, 5e, 5d, 5h, 6, 6a, 6b are communicated together by the annular gasket 35c, 35d, 35e, or 35h in the adjacent first flow path 1 or second flow path 2, the fluid leaking out of the inner gasket member 32c′ or 32h′ does not flow into the first flow path 1 or the second flow path 2.

(69) Also, in the plate heat exchanger according to the present embodiment, the fluid supply hole 7 is formed in the heat transfer plate 20 to supply a third fluid into the leakage flow path 4 or the leakage collectors 5a and 5b. Since the third fluid is supplied from the fluid supply hole 7 to the leakage flow path 4 or the leakage collectors 5a and 5b, it is possible to expel oxygen from the air initially existing in the leakage flow path 4 or the leakage collectors 5a and 5b. Note that an inert gas such as nitrogen, or pure water can be used as the third fluid.

(70) Also, in the plate heat exchanger according to the present embodiment, the drain channel 5v continuous with the drain holes 5c, 5e, 5d, 5h, 6, 6a, 6b is formed in one of the fixed frame 11 and the movable frame 12 which sandwich the plurality of stacked heat transfer plates 20; the drain nozzle 8 is mounted on the drain channel 5v; and a sensor adapted to detect a fluid is connected to the drain nozzle 8. This makes it possible to detect any leakage of fluid from the drain nozzle 8. The sensor accurately detects, for example, any or all of the temperature, pressure, leakage amount, and components of the leaking fluid, and thereby allows proper remedial measures to be taken.

(71) Also, in the plate heat exchanger according to the present embodiment, the passage holes 21, 22, 23, and 24 are formed in respective corners of the heat transfer plate 20. Consequently, for example, in a certain heat transfer plate 20, if the upper left passage hole 21 is used as an inlet of the high-temperature fluid H and the lower left passage hole 22 is used as an outlet of the high-temperature fluid H, the high-temperature fluid H flows from the upper part to the lower part of the heat transfer plate 20. Also, in adjacent heat transfer plates 20, if the lower right passage hole 24 is used as an inlet of the low-temperature fluid C and the upper right passage hole 23 is used as an outlet of the low-temperature fluid C, the low-temperature fluid C flows from the lower part to the upper part of the heat transfer plate 20. This makes it possible to exchange heat efficiently between the high-temperature fluid H and the low-temperature fluid C.

(72) Also, in the plate heat exchanger according to this fourth embodiment, the passage holes 21, 22, 23, and 24 are formed generally in a line in the length direction of the heat transfer plate 20. Consequently, upper inner, lower inner, lower outer, and upper outer passage holes 21, 22, 24, and 23 are formed in a line. For example, in a certain heat transfer plate 20, if the upper inner passage hole 21 is used as an inlet of the high-temperature fluid H and the lower inner passage hole 22 is used as an outlet of the high-temperature fluid H, the high-temperature fluid H flows from the upper inner part to the lower inner part of the heat transfer plate 20. Also, in adjacent heat transfer plates 20, if the lower outer passage hole 24 is used as an inlet of the low-temperature fluid C and the upper outer passage hole 23 is used as an outlet of the low-temperature fluid C, the low-temperature fluid C flows from the lower outer part to the upper outer part of the heat transfer plate 20. This makes it possible to exchange heat efficiently between the high-temperature fluid H and the low-temperature fluid C. Note that the phrase “generally in a line” includes “exactly in a line.”

Other Embodiments

(73) The present invention is not limited to the embodiments described above and various changes can be made to the embodiments. For example, the low-temperature-fluid communicating-path forming gasket 32c and the high-temperature-fluid communicating-path forming gaskets 32h may adopt double-line gaskets in the first and second embodiment as well. On the other hand, the low-temperature-fluid communicating-path forming gasket 32c according to the third and fourth embodiments may be a single-line gasket. Also, the communicating hole continuous with the low-temperature fluid leak detection drain hole 5e and the high-temperature fluid leak detection drain hole 5d may be provided in the movable frame rather than in the fixed frame 11.

REFERENCE SIGNS LIST

(74) 1 . . . First flow path 2 . . . Second flow path 3 . . . Communicating path 3c . . . Low-temperature-fluid communicating-path 3h . . . High-temperature-fluid communicating-path 4 . . . Leakage flow path 5a . . . First leakage collector 5b . . . Second leakage collector 5c, 5e . . . Low-temperature fluid leak detection drain hole 5d, 5h . . . High-temperature fluid leak detection drain hole 5v . . . Drain channel 6, 6a, 6b . . . Drain hole 7 . . . Fluid supply hole 8 . . . Drain nozzle 9 . . . Fluid supply nozzle 11 . . . Fixed frame 12 . . . Movable frame 20 . . . Heat transfer plate 21, 22, 23, 24 . . . Passage hole 31a . . . First flow-path forming gasket 31b . . . Second flow-path forming gasket 32a . . . Inner gasket member 32b . . . Flow-path forming gasket 32c . . . Low-temperature-fluid communicating-path forming gasket 32c′ . . . Inner gasket member 32c″ . . . Outer gasket member 32h . . . High-temperature-fluid communicating-path forming gasket 32h′ . . . Inner gasket member 32h″ . . . Outer gasket member 33 . . . Peripheral gasket 34 . . . Local gasket 35c, 35d, 35e, 35h . . . Annular gasket C . . . Low-temperature fluid Cm . . . Leaking low-temperature fluid and low-temperature fluid likely to leak H . . . High-temperature fluid Hm . . . Leaking high-temperature fluid and high-temperature fluid likely to leak