BACKGROUND OF THE INVENTION
Field of the Invention
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The present invention relates a condenser that serves as a plate-heat exchanger in which a plurality of heat exchange plates are combined together into a united body, and especially to such a condenser, which permits to remove quickly condense generated on the plates so as to ensure an effective progress of heat exchange of a gaseous fluid and condensation thereof.
Description of the Related Art
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Concerning condensers used in gradient power generation, steam power, chemical plants, food engineering plants, refrigerators and heat pumps, for the purpose of making heat exchange between a high temperature fluid and a low temperature fluid to conduct a phase change of the high temperature fluid from a gaseous phase to a liquid phase, there have been known various types of condenser such as a multitubular condenser, a plate-type condenser or a spiral condenser. Such a condenser is used also for an apparatus for extracting fresh water from seawater (a desalination apparatus) so as to condense steam supplied through evaporation of seawater to obtain fresh water in the condenser.
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In the condenser, a temperature of the low temperature fluid is increased by heat exchange made between the high temperature fluid and the low temperature fluid through heat transfer sections, while the high temperature fluid passing through an independent passage is condensed into condensate. The condensate is normally discharged from an outlet for the high temperature fluid, which is provided on the lower side of the above-mentioned passage. However, the condensate, which has been generated through condensation, flows directly down within the condenser, with the result that an amount of condensate becomes larger toward the lower side of the condenser. The condensate flowing down may spread over the surface of the heat transfer section in the form of a layer to inhibit a smooth heat transfer between the gaseous high temperature fluid and the heat transfer section, thud deteriorating condensation efficiency.
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Especially, the plate-type heat exchanger, which is used as a condenser, has a structure in which a plurality of plates are placed one upon another in parallel with each other so as to provide alternately high temperature fluid-passages and low temperature fluid-passages in gaps between the plates, thus permitting to make heat exchange between the fluids through the plates. The gaps, which are provided between the plates to form the passages for the fluids, are relatively small, with the result that a smooth discharge of condensate may not be ensured. Retention of the condensate in the condenser has an adverse influence on heat transfer performance between the gaseous high temperature fluid and the plates.
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There has recently been proposed a condenser that utilized plate-shaped heat transfer sections placed by a relatively short distance as in the plate-type heat exchanger and had an improved configuration of the heat transfer sections to discharge smoothly condensate.
Japanese Patent Provisional Publication No. 2000-346583 discloses an example of the condenser in which the heat transfer sections are provided on the surface thereof with a plurality of grooves to enhance discharging property of condensate.
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Such a conventional condenser includes plates having heat transfer sections, each of which has condensate-discharging gutters provided in the form of grooves on plate-shaped heat transfer sections in an oblique direction, and a condensate passage area provided in the form of a groove so as to extend in a longitudinal direction at a center of the heat transfer section and communicate with the above-mentioned condensate-discharging gutters. The condensate, which is generated on the surface of the heat transfer section through condensation and flows down, is collected by the condensate-discharging gutters and then gathered into the condensate passage area, thus enabling the condensate to flow down along the condensate passage area toward a discharge port of the condenser. It is possible to effectively prevent the condensate from being retained on the surface of the heat transfer section, enhance contact efficiency between the gaseous high fluid and the heat transfer section and improve heat transfer from the high temperature fluid to the low temperature fluid through the heat transfer sections, thus increasing condensation efficiency of the gaseous high temperature fluid.
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The conventional condenser that has a structure described in
Japanese Patent Provisional Publication No. 2000-346583 seeks to use the groove or gutter portions to quickly remove the condensate from the surface of the heat transfer sections. However, there is no substantial difference between this conventional condenser and further previously existing condensers in a discharging system in which the condensate flows down to the lower side of the heat transfer sections and then is discharged from the condenser. More specifically, a certain shape of a discharge port of the condensate may causes the condensate to be retained on the lower side of the passage to hinder an appropriate contact between the surface of the heat transfer sections and the gaseous high temperature fluid on the lower side of the heat transfer sections. Slow flow of the condensate, which flows down via the groove or gutter portions from the surface of the heat transfer sections, may overflow from these groove or gutter portions to spread over the surface of the heat transfer sections in the form of a layer. There is also involved a problem of hindrance in contact between the surface of the heat transfer sections and the gaseous fluid.
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If it is possible to prevent the condensate from flowing down while spreading over the surface of the heat transfer section, it is expected to increase an effective contact area between the gaseous heat exchange fluid and the plates to improve condensation efficiency.
SUMMARY OF THE INVENTION
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An object of the present invention, which was made to solve the above-mentioned problems, is therefore to provide a condenser, which includes a plurality of holes scattered over a predetermined area of a plate to discharge quickly condensate generated on the surface of the plate from a gap between the plates, permits prevention of deterioration of heat transfer efficiency due to retention of the condensate in the condenser, and ensure an appropriate contact between a gaseous heat exchange fluid and the surface of the plate to provide a high condensation efficiency.
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In order to attain the aforementioned object, a condenser of the first aspect of the present invention comprises a plurality of heat exchange plates each having first and second opposite surfaces, the heat exchange plates being combined together into a united body in a stacked state in which adjacent two plates of the heat exchange plates face each other on a same surface to provide alternately first and second gap portions between the heat exchange plates in a stacking direction thereof, each of the first gap portions being defined by the first surfaces of a pair of adjacent two plates of the heat exchange plates and each of the second gap portions being defined by the second surfaces of another pair of adjacent plates thereof, heat exchange being made between a first heat exchange fluid, which passes through the first gap portions, and a second heat exchange fluid, which passes through the second gap portions, through the heat exchange plates to make a phase change from a gaseous phase in a form of which the first heat exchange fluid is introduced, into a liquid phase, wherein: each of the heat exchange plates is provided on at least part thereof with a heat transfer section having a predetermined pattern of irregularity, the heat transfer section having opposite surfaces which are brought into contact with the first and second heat exchange fluids, respectively, each of the heat exchange plates having a predetermined configuration so that the adjacent plates of the heat exchange plates as stacked come into contact with each other at a part of the heat transfer section and at least a part of a peripheral portion of the heat exchange plate, to provide alternately the first and second gap portions between the heat exchange plates; the heat transfer section of each of the heat exchange plates has a plurality of condensate-discharging grooves and a plurality of condensate-discharging holes, the condensate-discharging grooves being formed on the heat exchange plate so as to continuously extend in an oblique direction, by a predetermined distance, relative to a direction along which the first heat exchange fluid flows down in the first gap portion, by a predetermined angle, and each of the condensate-discharging holes being formed at intersections of the condensate-discharging grooves; the heat transfer section has a plurality of tubular projections formed on the second surface of the heat exchange plate and a plurality of tongue-shaped projections formed on the first surface of the heat exchange plate, each of the tubular projections projecting, on the second surface of the heat exchange plate, from a portion of the heat transfer section, which defines the condensate-discharging hole, and each of the tongue-shaped projections projecting, on the first surface of the heat exchange plate, from the portion of the heat transfer section, which defines the condensate-discharging hole in an opposite direction to the tubular projection; and combining the heat exchange plates together into the united body causes the tubular projections of the heat exchange plate to be connected to the corresponding tubular projections of the adjacent heat exchange plate in a form of conduits to provide a non-communicating state between the condensate-discharging holes and the second gap portions, on one hand, and the tongue-shaped projections of the heat exchange plate to be connected to the corresponding tongue-shaped projections of the adjacent heat exchange plate in a form of gutters to provide a communicating state between the condensate-discharging holes and the first gap portions, on the other hand, so as to form a continuous passage, which passes linearly through the heat exchange plates in the stacking direction thereof, includes the condensate-discharging holes, and communicates only with the first gap portions, the continuous passage enabling condensate generated in the first gap portions to move in the stacking direction of the heat exchange plates.
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According to the first aspect of the present invention, each of the heat exchange plates of which a plate-type heat exchanger serving as a condenser is composed, has the condensate-discharging grooves, which collects condensate and causes it flow down, and the condensate-discharging holes, which are formed at intersections of the condensate-discharging grooves. When these plates are placed one upon another in parallel with each other and combined into a united body serving as the condenser, there is provided a continuous passage, which passes linearly through the heat exchange plates in the stacking direction thereof, includes the condensate-discharging holes, and communicates only with the first gap portions, but does not communicate with the second gap portions. The continuous passage communicates with an outside of the condenser. When the condenser is operated, condensate generated on the surface of the plates through heat exchange is collected by the condensate-discharging grooves and then flows into the condensate-discharging holes, with the result that the condensate flows through the continuous passage including the condensate-discharging holes to be discharged quickly to a subsequent unit, without flowing the lower side of the condenser. It is therefore possible to decrease an amount of the condensate, which moves down to the lower side of the condenser, thus preventing the condensate from spreading over the surface of the plates in the form of a layer. As a result, a major part of the plate can serve as an effective heat transfer area for a gaseous heat exchange fluid. Heat transfer efficiency between the plates and the gaseous heat exchange fluid can therefore be enhanced to improve condensation efficiency, thus providing a high performance condenser.
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The condenser according to the second aspect of the present invention may further comprises: a shell having a box shape, the shell covering an outside of the heat exchange plates as combined together into the united body, ensuring independent flowing states of the first and second heat exchange fluids in the respective first and second gap portions, and preventing the first and second heat exchange fluids from leaking outside; the shell is provided, on positions thereof that face the condensate-discharging holes of the heat exchange plates received in the shell, with a plurality of condensate-discharging ports formed thereon so as to communicate with the condensate-discharging holes, the shell comprising at least one header that encloses the condensate-discharging ports from an outside to cause an inside of the header to communicate with the condensate-discharging ports, the header being connected to an external duct line for recovery of condensate.
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According to the second aspect of the present invention, the shell is provided, on positions thereof that face the condensate-discharging holes of the heat exchange plates received in the shell, with a plurality of condensate-discharging ports formed thereon so as to communicate with the condensate-discharging holes. The shell has the header that communicates with the condensate-discharging ports and is connected to an external duct line for recovery of condensate. Accordingly, the condensate, which has reached the condensate-discharging holes, is directly introduced to an outside of the shell at the shortest distance to be discharged smoothly without causing retention of the condensate. In addition, it is possible to recover effectively the condensate flowing out of the condensate-discharging ports and steam leaking therefrom by the header, thus supplying the recovered condensate and steam with appropriate pressure and temperature condition to a subsequent unit. The condensation efficiency can therefore be further improved, without exerting adverse influence on progress of condensation in the condenser.
BRIEF DESCRIPTION OF THE DRAWINGS
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- FIG. 1 is a front view of a condenser according to an embodiment of the present invention;
- FIG. 2 is a back view of the condenser according to the embodiment of the present invention;
- FIG. 3 is a right-hand side view of the condenser according to the embodiment of the present invention;
- FIG. 4 is a front view of a heat exchange plate of the condenser according to the embodiment of the present invention;
- FIG. 5 is an enlarged front view illustrating a condense-discharging hole of the heat exchange plate of the condenser according to the embodiment of the present invention;
- FIG. 6 is an enlarged back view illustrating the condense-discharging hole of the heat exchange plate as shown in FIG. 5;
- FIG. 7 is a cross-sectional view cut along the line VII-VII in FIG. 5;
- FIG. 8 is a cross-sectional view cut along the line VIII-VIII in FIG. 5;
- FIG. 9 is a descriptive view illustrating a staking step for placing the heat exchange plates one upon another in order to manufacture the condenser of the present invention; and
- FIG. 10 is a descriptive view illustrating the staking step in which a heat exchange plate is further placed on a set of the stacked heat exchange plates as shown in FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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Now, an embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 10. An example in which the present invention is applied to a condenser used for a desalination apparatus in the embodiment will be described below. FIG. 1 is a front view of a condenser according to the first embodiment of the present invention; FIG. 2 is a back view of the condenser according to the first embodiment of the present invention; FIG. 3 is a right-hand side view of the condenser according to the first embodiment of the present invention; FIG. 4 is a front view of a heat exchange plate of the condenser according to the first embodiment of the present invention; FIG. 5 is an enlarged front view illustrating a condense-discharging hole of the heat exchange plate of the condenser according to the first embodiment of the present invention; FIG. 6 is an enlarged back view illustrating the condense-discharging hole of the heat exchange plate as shown in FIG. 5; FIG. 7 is a cross-sectional view cut along the line VII-VII in FIG. 5; FIG. 8 is a cross-sectional view cut along the line VIII-VIII in FIG. 5; FIG. 9 is a descriptive view illustrating a staking step for placing the heat exchange plates one upon another in order to manufacture the condenser of the present invention; and
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FIG. 10 is a descriptive view illustrating the staking step in which a heat exchange plate is further placed on a set of the stacked heat exchange plates as shown in FIG. 9.
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As shown in these figures, the condenser 1 according to the embodiment of the present invention serves as one of structural components of a desalination apparatus. The condenser is composed of a shell 20 having a box shape, which is connected, through conduits, to a decompressing vessel of a flash vaporizer (not shown) that also serves as another of the structural components of the desalination apparatus, and of a plurality of heat exchange plates 10, which are received in the shell 20 in a combined state. Of gap portions provided between the plates, there are provided alternately the first gap portions 51 through which steam, which is supplied in the form of the first heat exchange fluid from the vaporizer, passes, on the one hand, and there are provided alternately the second gap portions 52 through which a cooling water serving as the second heat exchange fluid, passes, so as to condense the supplied steam through heat exchange between the steam and the cooling water through the heat exchange plates 10.
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Each of the heat exchange plates is press-formed of a metallic thin sheet having a rectangular shape into a plate, which is provided in the center thereof with one or more heat transfer section 11 having a pattern of irregularity, and at a peripheral portion of the plate, with which the heat transfer section 11 is surrounded, with a flange 12.
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The above-mentioned heat transfer section 11 is a region, which has the optimized pattern of irregularities, so that a high temperature heat exchange fluid (i.e., the first heat exchange fluid) is to come into contact with one surface of the heat transfer section 11 and a low temperature heat exchange fluid (i.e., the second heat exchange fluid) is to come into contact with the other surface thereof, in order to make heat exchange. As shown in FIG. 4, the heat transfer section 11 has three sub-sections, and each sub-section has openings 11a, 11b, which are formed thereon at opposite end side portions in the vertical direction so as to serve as an inlet and an outlet through which the first heat exchange fluid, i.e., steam is supplied and discharged, respectively. The sub-section has fluid guiding zones 11c, which have a pattern of irregularity for ensuring introduce and discharge of the first heat exchange fluid are formed in the vicinity of the openings 11a, 11b on the opposite sides of the sub-section so to substantially surround the respective openings 11a, 11b. The fluid guiding zone 11c has projections 11e formed on the surface of the plate so as to be aligned along curved lines extending from the openings 11a, 11b to a boundary of a main heat transfer zone 11d. The projections 11e are placed so as to be symmetrical relative to the opening 11a or 11b.
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The main heat transfer zone 11d, which is placed in the center of the heat transfer section 11, is provided with condense-discharging grooves 13 that are formed on the surface (i.e., the first surface) of the plate so as to extend in an oblique direction, by a predetermined distance, to the vertical line of the heat exchange plate 10 placed vertically. More specifically, the condense-discharging grooves 13 are provided in the form of a plurality of pairs of V-shaped grooves. In addition, condensate-discharging holes 14 are formed at intersections of the condensate-discharging grooves 13, i.e., at the lowermost position of the V-shaped groove. The main heat transfer zone 11d has a known pattern of irregularity for providing an excellent heat transfer performance, except for the above-described specific structure.
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The heat transfer section 11 is symmetrical relative to a central vertical line in positions of the condense-discharging grooves 13, the condensate-discharging holes 14 and the other projections and recesses. In addition, the heat transfer section 11 is also symmetrical relative to a central horizontal line in positions of the openings 11a, 11b, the fluid guiding zones 11c and the condensate-discharging holes 14. When the heat exchange plate 10 is placed on the other heat exchange plate 10 having the same structure so that the inner surfaces of them face each other and the latter is positioned upside down, these plates have a face-to-face relationship in positions of the openings, the holes and the fluid guiding zones 11c. Accordingly, these two plates come into contact with each other at their projected portions.
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The heat transfer section 11 of each of the heat exchange plate 10 has the condensate-discharging holes 14 as described above. The heat transfer section 11 has a plural pairs of tongue-shaped front projections 15, each pair of which is formed on the front (i.e., first) surface of the heat exchange plate so as to project from a hole-defining peripheral portion of the plate, as shown in FIG. 5. The tongue-shaped projections 15 are placed at other positions of the above-mentioned hole-defining peripheral portion of the plate, than positions at which the condense-discharging grooves 13 communicate with the condensate-discharging holes 14. In addition the above-mentioned heat transfer section 11 has a plurality of tubular rear projections 16, each of which is formed on the rear (i.e., second) surface of the heat exchange plate, so as to project from the hole-defining peripheral portion of the plate, as shown in FIG. 6.
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The flange 12 is composed of flat portions 12a, which are bent toward the rear side of the heat exchange plate 10 along the longitudinal lines thereof and bulge portions 12b, which are bent toward the front side of the heat exchange plate 10 along the lateral lines thereof so as to deviate from the flat portions 12a. When the heat exchange plates 10 are placed in parallel one upon another, the adjacent two plates come into contact with each other at their flat portions 12a and bulge portions 12b. In such a state, the non-contact portions of these two plates define upper and lower openings, which communicate with the second gap portions 52 formed between the plates so as to serve inlet and outlet portions for a cooling water, i.e., the second heat exchange fluid. The positions of the openings may be optionally set by changing the positional relationship between the flat portions 12a and the bulge 12b of the flange 12.
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Steps for stacking the heat exchange plates 10 are carried out in a manner that the heat exchange plate 10 is placed on the other heat exchange plate 10 having the same structure so that the inner surfaces of them face each other and the latter is positioned upside down, and these plates are joined, by an appropriate joining method such as a diffusion bonding, at their contact areas such as the projections of the pattern of irregularity of the heat transfer sections 11 of the adjacent plates 10, the flanges 12, the tongue-shaped projections 15 formed in the vicinity of the condensate-discharging holes 14, and the tubular rear projections 16 formed in the vicinity thereof. After completion of the step for joining the heat exchange plates 10 into a united body, there are provided, at space between non-joined portions of the plates, the first gap portions 51 that are placed alternately between the front surfaces of the plates, and the second gap portions 52 that are placed alternately between the rear surfaces of the plates. The first gap portions 51 serve as passages through which the first heat exchange fluid, i.e., steam flows, and the second gap portion 52 serve as passages through which the second heat exchange fluid, i.e., a cooling water passes. A set of plates as joined in this manner is secured into a shell 20 to provide the condenser 1.
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In the set of the heat exchange plates 10 as joined, the tubular rear projections 16, which has a function of isolating the inside of the condensate-discharging holes 14, of one of the adjacent two plates come into contact with the corresponding tubular rear projections 16 of the other thereof in the second gap portion 52 and these projections are joined together to provide a non-communicating state between the condensate-discharging holes 14 and the second gap portions 52. The tongue-shaped front projections 15 of one of the adjacent two plates come into contact with the corresponding tongue-shaped front projections 16 of the other thereof in the first gap portion 51 and these projections are joined together in a form of gutters to provide a communicating state between the condensate-discharging holes 14 and the first gap portions 51, thus permitting the condensate to flow into the condensate-discharging holes 14. The continuous passage, which passes linearly through the heat exchange plates in the stacking direction thereof, includes the condensate-discharging holes 14, and communicates only with the first gap portions 51. The continuous passage therefore enables condensate generated in the first gap portions 51 to move in the stacking direction of the heat exchange plates.
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The above-mentioned shell 20 includes a metallic box having a size encompassing the heat exchange plates 10 as joined. The shell 20 is provided on one side wall thereof with steam inlet/ outlet openings 21, 22, which are connected to the upper and lower openings 11a, 11b, as shown in FIG. 4, which are associated with the first gap portions 51 between the plates as combined in parallel with each other. In addition, the shell 20 is provided on the upper wall thereof with a cooling water discharge port 23, which is connected to the upper openings associated with the second gap portions 52 between the plates as combined in parallel with each other, and on the lower upper wall thereof with a cooling water supply port 24, which is connected to the lower openings associated with the second gap portions 52 between the plates. The shell 20 has a sealing structure that isolates the respective gap portions 51, 52 from the outside in a reliable manner, excepting these openings 21, 22, and the discharge port 23 and the supply port 24 for the heat exchange fluids. The shell 20 has in its inside a mounting device having projecting members, which are placed at predetermined intervals so as to be inserted into spaces between the flanges 12 of the heat exchange plates 10 as joined together. The heat exchange plates 10 are received in the shell 20 so that the projecting members of the mounting device are inserted into the above-mentioned spaces to hold them. As a result, the first gap portions 51 and the second gap portions 52 are completely isolated from each other in the shell 20, without communicating with each other.
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An inlet header 27 having a box shape is mounted on the outer surface of the upper portion of the side wall of the shell 20 so as to encompass the inlet openings 21 and isolate them from the outside, as shown in FIG. 1. An outlet header 28 having the same box shape is mounted on the outer surface of the lower portion of the side wall of the shell 20 so as to encompass the outlet openings 22 and isolate them from the outside. A conduit for supplying steam is connected to the inlet header 27 and a conduit for discharging condensate is connected to the outlet header 28.
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As shown in FIG. 2, the shell 20 is provided on the other opposite side wall to the above-mentioned side wall with discharge openings 25, which communicate with the condensate-discharging holes 14 of the heat exchange plates 10 at positions on extended lines from the condensate-discharging holes 14. Headers 26 having a half round tubular shape are mounted on the outer surface of the above-mentioned side wall so as to encompass the discharge openings 25. These headers 26 are connected to external conduits. Condensate that flows from the condensate-discharging holes 14 to reach the discharge openings 25 is collected by the header 26 and then supplied to subsequent units such as an auxiliary condensation unit and a tank, which are placed on the downstream side of the condenser 1.
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Now, description will be given below of flow of the heat exchange fluids between the plates of the condenser according to the embodiment of the present invention. Roughly describing, steam free of salt content, which has been obtained through evaporation by means of an evaporator is subjected to a removing step for removing suspended liquid (mist) by a separator and then supplied to the condenser 1. The steam is subjected to heat exchange made through the heat transfer sections 11 with a cooling water serving as the second heat exchange fluid, i.e., seawater directly taken and having a relatively low temperature, to be cooled, with the result that the steam condenses on the surface of the heat transfer sections 11 to become water droplet.
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The phenomenon caused in the shell 20 of the condenser 1 will be described in detail below. High temperature steam in gaseous phase serving as the first heat exchange fluid is introduced from the outside of the shell 20 into the inside thereof through the inlet header 27 and the inlet openings on the upper side of the shell 20 and then flows into the first gap portions 51 through the openings 11a of the respective heat exchange plate 10. On the other hand, condensate obtained through condensation of the steam flows from the first gap portions 51 through the openings 11b of the heat exchange plate 10, and then passes through the outlet openings 22 and the outlet header on the lower side of the shell 20 to be discharged outside of the shell 20.
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Concerning the second gap portions 52 provided adjacently to the above-mentioned first gap portions 51 through the plates, a cooling water serving as the second heat exchange fluid is introduced from the outside of the shell 20 through the supply port 24 provided on the lower side thereof into the shell 20 and then supplied into the second gap portions 52 through the openings 22 provided on the lower side of the plates. The cooling water after completion of the heat exchange flows through the openings on the upper side of the plates, which are associated with the second gap portions 52, is discharged out of shell 20 through the upper discharge port 23. More specifically, the respective heat exchange fluids flow alternately in the respective first and second gap portions between the heat exchange plates 10 so as to provide a counter-flowing system in which the heat exchange fluids flow in the opposite directions to each other.
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In the first gap portion 51, the steam flows into a space between the heat transfer sections 11 through the upper openings 11a of the plate and comes into contact with the surface of the heat transfer section 11 in the first gap portion 51. Heat exchange between the stream and the cooling water through the heat transfer section 11 is made on the entire area of the heat transfer section 11 and the steam is cooled to progress condensation of the steam, with the result that condensate is generated on the surface of the heat transfer section 11. The generated condensate flows down along the surface of the heat transfer section 11 and flows into the adjacent condense-discharging grooves 13. The condensate flows down along the condense-discharging grooves 13 to reach the condensate-discharging holes 14. The condensate, which has reached the respective condensate-discharging holes 14, passes through the condensate-discharging holes 14 to move along the tongue-shaped front projections 15 and the tubular rear projections 16 in the stacking direction of the plates, and passes through the discharge openings 25 to reach finally the header 26. The condensate is therefore discharged outside of the condenser 1 to be supplied to the subsequent unit.
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The condensate generated on the heat transfer section 11 can directly be discharged out of the condenser 1 so as to avoid an unfavorable phenomenon that a full amount of condensate generated at various zones on the heat transfer section 11 flows down in the first gap portions 51 to cause the condensate to retain on the lower side of the first gap portions 51 in a large amount. It is therefore possible to prevent the condensate from spreading over the surface of the heat exchange plate 10 in the form of a layer on the lower side of the heat transfer section 11, especially of the first gap portions 51. A wide contact area between the steam and the surface of the plates can be ensured, thus causing a progress of effective condensation.
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A part of steam flows together with the condensate to reach the discharge opening 25 through the condensate-discharging holes 14, with the result that the part of steam is discharged together with the condensate from the discharge opening 25 of the condenser 1 through the header 26. However, such a part of steam may be condensed appropriately by means of an auxiliary condensation unit, which is connected to the header 26 by the conduit, thus causing no problem.
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On the lower side of the first gap portions 51, condensate after condensation flows down along the heat transfer section 11 in the form of droplets, without entering the condense-discharging grooves 13 and the condensate-discharging holes 14, and enters smoothly the lower openings 11b, so as to be discharged smoothly out of the condenser 1 through the outlet openings 22 and the outlet header 28. The condensate, which has been discharged from the condenser 1 through the outlet header 28 and the header 26, is collected once by a tank. A predetermined amount of fresh water as reserved may be supplied to an outside for use.
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According to the condenser of the embodiment of the present invention, each of the heat exchange plates 10 has the condensate-discharging grooves 13, which collects condensate and causes it flow down, and the condensate-discharging holes 14, which are formed at intersections of the condensate-discharging grooves 13. When these plates are placed one upon another in parallel with each other and combined into a united body serving as the condenser, there is provided a continuous passage, which passes linearly through the heat exchange plates in the stacking direction thereof, includes the condensate-discharging holes 14, and communicates only with the first gap portions 51, but does not communicate with the second gap portions 52. The continuous passage communicates with an outside of the condenser 1. When the condenser is operated, condensate generated on the surface of the plates through heat exchange is collected by the condensate-discharging grooves 13 and then flows into the condensate-discharging holes 14, with the result that the condensate flows through the continuous passage including the condensate-discharging holes 14 to be discharged quickly to a subsequent unit, without flowing the lower side of the condenser 1. It is therefore possible to decrease an amount of the condensate, which moves down to the lower side of the condenser 1, thus preventing the condensate from spreading over the surface of the plates in the form of a layer. As a result, a major part of the plate can serve as an effective heat transfer area for a gaseous heat exchange fluid. Heat transfer efficiency between the plates and the gaseous heat exchange fluid can therefore be enhanced to improve condensation efficiency, thus providing a high performance condenser.
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The condenser according to the embodiment of the present invention may have any suitable structure, excepting that the condense-discharging grooves 13 and the condensate-discharging holes 14 are formed on the heat transfer sections of the heat exchange plates 10 so as to discharge directly the condensate. Change in shape of the flange 12 of the heat exchange plate 10, existence of the openings 11a, 11b, positions thereof, and positions of the openings provided in the shell 20 so as to correspond thereto may be made so that an appropriate relationship of the inlet and outlet for the heat exchange fluids relative to the position of the plates in the shell 20 can be provided based on an intended use of the condenser.
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In the above-described embodiment of the condenser of the present invention, each of the heat exchange plates 10 has a plural pairs of tongue-shaped front projections 15, each pair of which is formed on the front (i.e., first) surface of the heat exchange plate so as to project from a hole-defining peripheral portion of the plate, as shown in FIG. 5, so that a single kind of plates suffices for composing the condenser, by placing the alternate plates upside down. However, the present invention is not limited only to such an embodiment. More specifically, two kinds of plates, which provide the same structure of the joined plate as described above, without placing the alternate plates upside down, may be used so that the same kind of plates is placed alternately. In this modification, the single tongue-shaped front projection 15 may be formed only on the lower side of the condensate-discharging hole 14. In such a case, it is possible to receive the condensate not only by the condense-discharging grooves 13, but also by the condensate-discharging hole 14, thus improving removability of the condensate from the surface of the plate.
