JP4972547B2 - Multistage flash evaporator - Google Patents

Description

  The present invention relates to a multistage flash evaporator used for seawater desalination, for example.

Conventionally, as a multistage flash evaporator (MSF) used for seawater desalination, as shown in Patent Documents 1 and 2 below, a plurality of housings maintained in a reduced pressure state are provided, and upper portions of the respective housings are provided. A condensate tube bundle is provided, a bowl-shaped condensate receptacle is provided below the condensate tube bundle, and a demister is provided at at least one of the front and rear steam inlets of the condensate tube bundle in the housing. The evaporating chamber and the condensing part are divided by the demister and the bowl-shaped condensate receiver, and heated brine (seawater) is introduced into the evaporating chamber of each housing through the orifice and flash-evaporated.
JP 2000-84302 A JP 2000-107501 A

  In the conventional multistage flash evaporator described in Patent Documents 1 and 2, is the demister provided in each housing a demister (20) made of a knitted wire mesh as shown in FIG. 8, for example? Or, for example, as shown in FIG. 9, it was an expandable wire mesh demister (21).

  However, the conventional knitted woven wire mesh demister (20) shown in FIG. 8 is formed by knitting a thin wire mesh into a knit shape, and by laminating these, the opening between the wire meshes is small, and the scale is deposited around the wire mesh. The structure is such that the wire mesh closes after a while, and in particular, a scale mainly composed of magnesium hydroxide: Mg (OH) 2 in seawater precipitates and accumulates in the high temperature stage of the evaporator, Due to the blockage of the demister (20), the purity of the produced distilled water has deteriorated, the seawater desalination unit must be frequently stopped, the wire demister (20) must be pickled and the scale removed. There was a problem that the cleaning work was very troublesome and troublesome.

  On the other hand, in the conventional expanded wire mesh demister (21) shown in FIG. 9, since the opening between the meshes is wide and the surface area is small, the salt content accompanying the water vapor during the passage of the demister (21) is reduced. There was a problem that the minute water droplets (mist) contained could not be sufficiently removed, and the mist removal efficiency was poor.

  The object of the present invention is to solve the above-mentioned problems of the prior art, use a vane type demister in a multi-stage flash evaporator, greatly increase the efficiency of mist removal, and reduce scale deposition and deposition on the demister. In order to provide a multi-stage flash evaporator that can be operated continuously for a long time without shutting down the equipment, and can reduce the loss of distilled water produced by shutting down the equipment and the cost of pickling the demister. It is in.

  As a result of intensive research in view of the above points, the present inventors have used, as a demister of a multi-stage flash evaporator, a demister that is composed of a vane-type demister composed of vapor colliding plates having a corrugated cross section arranged in parallel. The inventors have found that the deposition and deposition of scale on the surface can be reduced, and have completed the present invention.

In order to achieve the above object, the invention of a multistage flash evaporator according to claim 1 includes a plurality of housings maintained in a reduced pressure state, and a condenser tube bundle is provided at the top of each housing. A bowl-shaped condensate receptacle is provided below, and a demister is provided at a steam inflow portion on at least one of the front and rear sides of the condenser tube bundle in the housing. The lower portion of the housing serves as an evaporation chamber. In the multistage flash evaporator, in which the upper part is a condensation chamber, and heated brine is sequentially flowed into the evaporation chamber of each housing through the orifice and flash-evaporated, in the multi-stage flash evaporator, the demisters provided at the steam inflow portions on both sides of the condenser tube bundle in each housing Is constituted by a vane type demister consisting of steam impingement plates with a corrugated cross section arranged in parallel at predetermined intervals. , The vane-type demister is disposed in a vertical direction on both sides of the steam inlet portion before and after the condensation tube bundle in each housing, zigzag gap between the steam impingement plate between the demister is formed in the horizontal direction, the housings A plurality of rectifying plates for guiding water vapor generated in the lower part of the evaporation chamber of the housing to a horizontal zigzag gap between the vapor collision plates of the vane type demister are provided at the upper part of the evaporation chamber of each of the housings. After the water vapor generated in the lower part of the evaporation chamber is guided by a plurality of rectifying plates, it passes through the zigzag gap between the cross-sectional corrugated vapor collision plates of the vane type demister in the horizontal direction , and during the passage, scale Lumpur component of trace water droplets (mist) in contained in water vapor, it flows down the evaporation chamber side along the wall surface with water droplets adhering to the wall surface of the cross-sectional waveform steam impingement plate, the vane demister Steam having passed through the zigzag gap between the steam impingement plate to each other, it is characterized in that is adapted to contact the condensing tube bundle.

A second aspect of the invention is the multistage flash evaporator according to the first aspect, wherein water vapor generated in the lower part of the evaporation chamber of each housing is placed between the vapor collision plates of the vane type demister between the upper parts of the evaporation chambers of the housings. A plurality of rectifying plates are provided to guide the horizontal zigzag gap between the steam corrugated steam collision plates of the vane demister after the water vapor generated in the lower part of the evaporation chamber is guided by the plurality of rectifying plates. It is characterized in that it passes through a zigzag gap between them in the horizontal direction .

The invention of claim 1 includes a large number of housings maintained in a reduced pressure state, and a condensate tube bundle is provided at the top of each housing, and a bowl-shaped condensate receiver is provided below the condensate tube bundle. A demister is provided at at least one of the front and rear sides of the condenser tube bundle, and a lower part of the housing serves as an evaporation chamber, and an upper part of the housing serves as a condensation chamber, which heats the evaporation chamber of each housing. In a multi-stage flash evaporator, in which brine is sequentially introduced through an orifice and flash-evaporated, demisters provided in the steam inflow portions on both sides of the condenser tube bundle in each housing are arranged in parallel at predetermined intervals. The vane demister is composed of a corrugated steam impingement plate, and the vane demister is disposed in front of the condenser tube bundle in each housing. Both sides of the steam inlet is arranged in a vertical direction, zigzag gap between the steam impingement plate between the demister is formed in the horizontal direction, water vapor generated in the evaporation chamber the bottom of each housing, vane-type demister the zigzag gap between the cross-sectional waveform steam impingement plates are passed through a horizontal, during its passage, scale Lumpur component traces in water droplets (mist) is contained in water vapor, cross-sectional waveform steam collide Water droplets that flow along the wall surface to the evaporation chamber side along with the water droplets adhering to the wall surface of the plate and pass through the zigzag gap between the vapor collision plates of the vane type demister are brought into contact with the condensation tube bundle. Therefore, according to the present invention, using a vane type demister in a multistage flash evaporator, the passage of water vapor to the demister is extremely smooth, and the deposition and deposition of scale on the demister Reduced, exhibits as a possible long-term continuous operation without stopping the apparatus, loss and the production of distilled water by stopping the device, the effect of reducing the cost of pickling the demister.

A second aspect of the invention is the multistage flash evaporator according to the first aspect, wherein water vapor generated in the lower part of the evaporation chamber of each housing is placed between the vapor collision plates of the vane type demister between the upper parts of the evaporation chambers of the housings. A plurality of rectifying plates are provided to guide the horizontal zigzag gap between the steam corrugated steam collision plates of the vane demister after the water vapor generated in the lower part of the evaporation chamber is guided by the plurality of rectifying plates. in which the zigzag gap are adapted to pass through in the horizontal direction between the, according to the present invention, by the action of the rectifying plate, drift of the mist entrained steam entering a vane demister installed in front condensing unit It is possible to suppress mist and to obtain mist removal efficiency as designed. Moreover, it is possible to take a countermeasure against drift without significantly changing the structure of the multistage flash evaporator. In addition, since the current plate plays the role of a mist scattering prevention plate, the mist load on the demister can be reduced.

It is an expanded cross-sectional view which shows embodiment of a multistage flash evaporator. It is an expansion perspective view of a vane type demister part. It is an expanded cross-sectional view of a multistage flash evaporator, and shows the modification of a baffle plate. The enlarged cross-sectional view shows another modification of the current plate. It is an enlarged front view which shows the example of the conventional knitting type | mold metal mesh demister. It is an enlarged front view which shows the example of the conventional expand type metal-mesh demister.

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  1 and 2 show an embodiment of a multi-stage flash evaporator according to the present invention. Here, FIG. 1 is a schematic cross-sectional view of a multistage flash evaporator according to the present invention, and FIG. 2 is a schematic perspective view of a vane demister.

  In this specification, front and rear, left and right are based on FIG. 1, front is the right side of FIG. 1, rear is the same left side, and left and right are frontward.

  First, referring to FIG. 1 and FIG. 2, the multistage flash evaporator of the present invention used for seawater desalination is provided with a large number of housings (1) maintained in a decompressed state in parallel. A condensate tube bundle (5) is provided over the entire length in the longitudinal direction of the housing (1) at the top of each housing (1), and a bowl-shaped condensate receptacle (6) is provided under the condensate tube bundle (5) over the entire length. The demisters (7) are provided over the entire length on both the front and rear sides of the condenser tube bundle (5) in the housing (1). The demister (7) and the bowl-shaped condensate receptacle (6) 1) The inside is divided into an upper evaporation chamber (2) and a lower condensing part (3).

  A pair of hanging plates (4) and (4) are arranged in the upper half of the central portion of each housing (1) in the longitudinal direction of the housing (1) and at a predetermined distance from each other. It is arranged in a state of entering the part from above. These hanging plates (4) and (4) are fixed to the ceiling (1d) of the housing (1) in a hanging shape at the center of the width of the housing (1) by means such as welding.

  And in this invention, as shown in FIG. 2, the demister (7) provided in the steam inflow part of the both sides before and behind the condensation pipe bundle (5) in each housing (1) of a multistage flash evaporator is a predetermined space | interval. It is comprised by the vane type | mold demister which consists of the vapor | steam collision board (8) of the cross-sectional waveform which was arrange | positioned in parallel and bent and produced the thin plate.

In each housing (1) of the multi-stage flash evaporator, a vane demister (7) made of parallel cross-sectional corrugated steam impingement plates (8) is disposed on both front and rear sides of the condenser tube bundle (5) in each housing (1). The steam impingement plate (8) (8) of the demister (7) is disposed in a vertical direction between the bowl-shaped condensate receptacle (6) and the ceiling (1d) inner surface of the housing (1). Zigzag-shaped gaps (9) between them are formed in the horizontal direction , and water vapor generated in the lower part of the evaporation chamber (2) of each housing (1) is corrugated in the cross section of the vane type demister (7). The zigzag gap (9) between the steam impingement plates (8) and (8) passes in the horizontal direction .

  Here, the water vapor generated in the lower part of the evaporation chamber (2) of each housing (1) passes through the zigzag gap (9) between the corrugated vapor collision plates (8) of the cross section of the vane type demister (7). However, during the passage, scale components such as magnesium hydroxide in a minute amount of water droplets (mist) contained in water vapor evaporate along the wall surface together with water droplets adhering to the wall surface of the corrugated vapor collision plate (8). Water vapor flowing down to the chamber (2) side and passing through the zigzag gap (9) between the vapor collision plates (8) and (8) of the vane type demister (7) is brought into contact with the condensation tube bundle (5). Has been made. Therefore, scale adherence hardly occurs to the demister (7), and even if the scale adheres, the gap (9) is difficult to close.

  In the evaporation chamber (2) below each housing (1), the orifice (10) includes a lower end portion of the rear side wall (1a) of the housing (1) and a lower end portion of the front side wall (1b) of each housing (1). A dam (13) having a horizontal wall (14) for increasing the exposed area at the upper end is provided on the downstream side of each orifice (10). Near the upper side of 13), a brine splash prevention plate (15) is provided horizontally.

  In the illustrated multistage flash evaporator, the housing (1) maintained in a decompressed state has a length in the left-right direction of, for example, 20 meters, and for example, 15 to 25 units of the housing (1) are arranged in parallel in the front and rear. Is provided. The length of the evaporation chamber of each housing (1) is, for example, about 3.5 meters.

  However, there are various scales of the multistage flash evaporator, particularly the length and shape of the housing (1), the number of installed bases, etc., and the multistage flash evaporator according to the present invention is not limited to the illustrated one.

  In the multistage flash evaporator, when heated brine (seawater) is introduced from the rear side of the evaporation chamber (2) through the multiple orifices (10) at the lower end of the rear wall (1a) of the housing (1), the heated brine is It flows over a dam (13) having a horizontal wall (14) at its upper end. In the meantime, it flashes and vapor is generated. The brine further flows into the evaporation chamber (2) of the next housing (1) from a number of orifices (10) at the lower end of the front side wall (1b) of the housing (1).

On the other hand, the water vapor flash-evaporated in the evaporation chamber (2) of the housing (1) is sent to the steam inflow portions on both the front and rear sides of the condenser tube bundle (5), and the bowl-shaped condensate receptacle (6) and the ceiling ( 1d) Condensing section (3) passing horizontally through a zigzag gap (9) between steam impingement plates (8) and (8) of demister (7) disposed vertically with respect to the inner surface Thus, during the passage of the demister (7), minute water droplets (mist) containing salt accompanying the water vapor are removed.

Such flash evaporation of the heating brine occurs over the entire length of the evaporation chamber (2), but the condensation section (3) of the housing (1) is provided with a condensation tube bundle (5) over the entire length, The flash vapor generated in 2) and passing through the demisters (7) arranged in the vertical direction to the steam inflow portions on both the front and rear sides of the condenser tube bundle (5) is connected to a number of condensing tubes (5) in the condensing unit (3). It quickly contacts and condenses, and the condensed water droplets are received by the bowl-shaped condensate receiver (6). For this reason, the passage of the steam to the demister (7) is smooth, the amount of passage of the flash steam is uniform, and the flow velocity distribution of the demister passing steam in the evaporation chamber (2) does not become uneven. As a result, the local water droplet separation performance of the demister (7) can be prevented from being deteriorated, the performance of the demister (7) can be maintained evenly as a whole, and the quality of the produced water is maintained at a high level. It is something that can be done.

  As described above, according to the present invention, the vane type demister (7) is used in the multi-stage flash evaporator to reduce the deposition and deposition of the scale (7) on the demister and can be continued for a long time without stopping the apparatus. It is possible to operate, and it is possible to reduce the amount of distilled water produced due to the shutdown of the apparatus and the cost of pickling the demister.

  The vane demister (7) does not need to be provided over the entire length of the condenser tube bundle (5) in the housing (1), and may be provided partially depending on circumstances. In this case, for example, a partition plate or the like is appropriately installed between the partial vane type demisters (7) so that the upper evaporation chamber (2) and the lower condensing part ( 3), it is necessary to prevent the water vapor flash-evaporated in the evaporation chamber (2) from contacting the condenser tube (5) without passing through the demister (7).

In this embodiment, the vapor generated in the lower part of the evaporation chamber (2) of the housing (1) is converted into the vapor collision plate (8) of the vane type demister (7) in the upper part of the evaporation chamber (2) of each housing (1). (8) A number of rectifying plates (11) and (12) are provided to guide the horizontal zigzag gap (9) between them.

  In each evaporation chamber (2), three sheets are provided between the front and rear side walls of the bowl-shaped condensate receptacle (6) and the inner surfaces of the front and rear side walls of the housing (1) on both front and rear sides of the condensation tube bundle (5). Vertical rectifying plates (11) are arranged in parallel with a predetermined distance from each other.

  Here, the first vertical rectifying plates (11a) (11a) close to the front and rear side walls of the bowl-shaped condensate receptacle (6) have the lowest height, and both the front and rear side walls of the bowl-shaped condensate receptacle (6). It is located so as to correspond to the middle part of the height.

  The next second vertical rectifying plates (11b) and (11b) have a height approximately 1.5 times the height of the first vertical rectifying plates (11a) and (11a), and the upper ends thereof are the first vertical rectifying plates. It has the same level as the upper ends of the plates (11a) and (11a), and extends downward from the lower ends of the first vertical rectifying plates (11a) and (11a).

  The third vertical rectifying plates (11c) and (11c) near the front and rear side walls of the housing (1) have the highest height and are approximately twice the height of the first vertical rectifying plates (11a) and (11a). The upper end of which is at the same level as the upper ends of the first vertical rectifying plates (11a) and (11a), and extends further downward from the lower ends of the second vertical rectifying plates (11b) and (11b), The lower end is arranged to be close to the heating brine (seawater) of the evaporation chamber (2).

In each evaporation chamber (2), between the vane demister (7) and the inner surface of the same side wall of the housing (1) on both sides of the vane demister (7) arranged in the vertical direction. Each of the three curved rectifying plates (12) is arranged in parallel with a predetermined distance from each other.

  Here, the 1st curve baffle plate (12a) (12a) corresponding to near the lower end part of vane type demister (7) is constituted by the arc-shaped part with the narrowest width and corresponding to a central angle of about 90 degrees. . The upper ends of the first curved rectifying plates (12a) and (12a) are arranged near the lower end of the demister (7) so as to face from the rear or the front, and the lower ends of the first curved rectifying plates (12a) and (12a) are The first vertical rectifying plate (11a) and the second vertical rectifying plate (11b) are arranged so as to face each other from above and slightly close to the second vertical rectifying plate (11b).

  The next second curved rectifying plates (12b) and (12b) positioned so as to correspond to the intermediate portion of the height of the vane type demister (7) are approximately 2 in width of the first curved rectifying plates (12a) and (12a). The arcuate portion having a double width and corresponding to a central angle of approximately 90 ° and a horizontal portion extending horizontally to the demister (7) side are formed. The upper ends of the second curved rectifying plates (12b) and (12b) are arranged so as to face the intermediate portion of the height of the demister (7) from the rear or the front. (12a) It is farther from the demister (7) than the upper end of (12a). The lower ends of the second curved rectifying plates (12b) and (12b) are respectively opposed to the intermediate portions of the second vertical rectifying plate (11b) and the third vertical rectifying plate (11c) from above, and are slightly third vertical rectifying plates. (11c) It is arranged so as to be located closer to it.

  The third curved rectifying plates (12c) (12c) near the front and rear side walls of the housing (1) are the widest and have a width approximately three times the width of the first curved rectifying plates (12a) (12a). And an arcuate portion corresponding to a central angle of approximately 90 ° and a wide horizontal portion extending horizontally to the demister (7) side. The upper ends of the third curved rectifying plates (12c) and (12c) are arranged so as to face the upper end of the demister (7) from the rear or the front, but the second curved rectifying plates (12b) ) (12b) is farther from the demister (7) than the upper end. The lower ends of the third curved rectifying plates (12c) and (12c) are opposed to the middle portions of the third vertical rectifying plate (11c) and the front and rear side walls of the housing (1) from above, and slightly of the housing (1). It is arranged so that it is located near both front and rear side walls.

In the multistage flash evaporator according to the present invention, the vapor generated in the lower part of the evaporation chamber (2) of the housing (1) is transferred to the upper part of the evaporation chamber (2) of each housing (1) by the vapor collision of the vane type demister (7). A total of six baffle plates (11) are provided to guide the horizontal zigzag gap (9) between the plates (8) and (8), and water vapor generated in the lower part of the evaporation chamber (2) After being guided by the three vertical rectifying plates (11a) (11b) (11c) and subsequently the three curved rectifying plates (12a) (12b) (12c), the crossing of the vane type demister (7) It passes through the zigzag gap (9) between the surface corrugated steam impingement plates (8) (8) in the horizontal direction .

  Therefore, by the action of these current plates (11a) (11b) (11c) (12a) (12b) (12c), the mist accompanying steam flowing into the vane type demister (7) installed in front of the condensing part (3) It is possible to suppress the drift and obtain the mist removal efficiency as designed. Moreover, it is possible to take a countermeasure against drift without significantly changing the structure of the multistage flash evaporator. Moreover, since the rectifying plates (11a), (11b), (11c), (12a), (12b), and (12c) serve as mist scattering prevention plates, the mist load applied to the demister (7) can be reduced.

  Note that the steam passing through the vane type demister (7) generally has a high flow rate of steam passing through the lower part of the demister (7) and a low flow rate of steam passing through the upper part of the demister (7). The first vertical rectifying plates (11a) and (11a) near the front and rear side walls of the bowl-shaped condensate receptacle (6) have the lowest height, and the second vertical rectifying plates (11b) and (11b) are The third vertical rectifying plates (11c) and (11c), which are approximately 1.5 times the height of the vertical rectifying plates (11a) and (11a) and are close to the front and rear side walls of the housing (1), The first curve corresponding to the height of the first vertical rectifying plate (11a) (11a) is approximately twice the height of the first vertical rectifying plate (11a) (11a) and corresponding to the vicinity of the lower end of the vane type demister (7). The current plates (12a) and (12a) have the narrowest width, and the second curved current plate (12b) ( 2b) has a width approximately twice the width of the first curved rectifying plates (12a) (12a), and the third curved rectifying plates (12c) (12c) near the front and rear side walls of the housing (1) are: It is the widest and has a width approximately three times the width of the first curved rectifying plates (12a) (12a), and the first to third vertical rectifying plates (11a) (11b) (11c) and The steam flow rectification by the first to third curved flow straightening plates (12a) (12b) (12c) is gradually increased so that the flow velocity of the steam passing through the vane demister (7) is averaged. Has been.

  According to such a multistage flash evaporator of the present invention, the passage of water vapor to the demister (7) is extremely smooth, reducing the deposition and deposition of scale on the demister (7), and without stopping the apparatus. Long-term continuous operation is possible, and the loss of production distilled water due to the stoppage of the apparatus and the cost of pickling the demister can be reduced.

FIG. 3 shows a first modification of the rectifying plate in the above embodiment of the multistage flash evaporator according to the present invention. Here, the difference from the case of the above embodiment is that the water vapor generated in the lower portion of the evaporation chamber (2) of the housing (1) is converted into a horizontal space between the steam collision plates (8) and (8) of the vane type demister (7). The rectifying plate for guiding to the zigzag gap (9) in the direction is constituted by three curved rectifying plates (12a) (12b) (12c), and the vertical rectifying plates (11a) (11b) (11c) The installation is omitted.

  Here, the shape of the three curved rectifying plates (12a), (12b), and (12c) and the arrangement locations are the same as those in FIG. That is, the first curved rectifying plate (12a) (12a) corresponding to the vicinity of the lower end of the vane type demister (7) is constituted by an arcuate portion having the narrowest width and corresponding to a central angle of approximately 90 °. The upper ends of the first curved rectifying plates (12a) and (12a) are arranged near the lower end of the demister (7) so as to face from the rear or the front, and the lower ends of the first curved rectifying plates (12a) and (12a) are The evaporating chamber (2) is disposed so as to face the brine at the bottom from above.

  The next second curved rectifying plates (12b) and (12b) positioned so as to correspond to the intermediate portion of the height of the vane type demister (7) are approximately 2 in width of the first curved rectifying plates (12a) and (12a). The arcuate portion having a double width and corresponding to a central angle of approximately 90 ° and a horizontal portion extending horizontally to the demister (7) side are formed. The upper ends of the second curved rectifying plates (12b) and (12b) are arranged so as to face the intermediate portion of the height of the demister (7) from the rear or the front. (12a) It is farther from the demister (7) than the upper end of (12a). The lower ends of the second curved flow rectifying plates (12b) and (12b) are arranged so as to face the brine below the evaporation chamber (2) from above.

  The third curved rectifying plates (12c) (12c) near the front and rear side walls of the housing (1) are the widest and have a width approximately three times the width of the first curved rectifying plates (12a) (12a). And an arcuate portion corresponding to a central angle of approximately 90 ° and a wide horizontal portion extending horizontally to the demister (7) side. The upper ends of the third curved rectifying plates (12c) and (12c) are arranged so as to face the upper end of the demister (7) from the rear or the front, but the second curved rectifying plates (12b) ) (12b) is farther from the demister (7) than the upper end. The lower ends of the third curved flow rectifying plates (12c) and (12c) are arranged so as to face the brine below the evaporation chamber (2) from above and slightly located near the front and rear side walls of the housing (1). ing.

According to the first modified example, although three vertical rectifying plates (11a), (11b), and (11c) are not attached, the water vapor generated in the lower portion of the evaporation chamber (2) is three pieces each. After being guided by the curved flow straightening plates (12a), (12b) and (12c), the zigzag gap (9) between the cross-sectional corrugated steam collision plates (8) and (8) of the vane type demister (7) is formed. It is designed to pass horizontally .

  Therefore, the curved rectifying plates (12a), (12b), and (12c) act to suppress the drift of the mist accompanying steam flowing into the vane type demister (7) installed in front of the condensing unit (3). Mist removal efficiency can be obtained. Moreover, it is possible to take a countermeasure against drift without significantly changing the structure of the multistage flash evaporator. In addition, since the curved rectifying plates (12a), (12b), and (12c) serve as mist scattering prevention plates, the mist load applied to the demister (7) can be reduced.

  Since the other points of the first modification are the same as those in the above embodiment, the same reference numerals are given to the same components in the drawings.

FIG. 4 shows a second modification of the rectifying plate in the above embodiment of the multistage flash evaporator according to the present invention, which is similar to the case of the first modification of the rectifying plate shown in FIG. A rectifying plate for guiding water vapor generated in the lower part of the evaporation chamber (1) of (1) to the horizontal zigzag gap (9) between the vapor collision plates (8) and (8) of the vane type demister (7). However, it is constituted by three curved rectifying plates (12a), (12b) and (12c), and mounting of the vertical rectifying plates (11a), (11b) and (11c) is omitted.

  And the difference from the case of the said 1st modification exists in the shape of three curved rectification | straightening plates (12a) (12b) (12c). That is, the first curved rectifying plate (12a) (12a) corresponding to the vicinity of the lower end portion of the vane type demister (7) is configured by a horizontal portion and a bent portion formed at the end portion on the housing side wall side. The upper ends (front ends of the horizontal portions) of the first curved rectifying plates (12a) and (12a) are arranged near the lower end portion of the demister (7) so as to face from the rear or the front, and the first curved rectifying plates (12a). The lower end of (12a) is arranged so as to face the brine below the evaporation chamber (2) from above.

  The next second curved rectifying plates (12b) and (12b) positioned so as to correspond to the intermediate portion of the height of the vane type demister (7) are approximately 2 in width of the first curved rectifying plates (12a) and (12a). It has a double width and is composed of a horizontal portion and a bent portion formed at the end portion on the side wall of the housing. The upper ends of the second curved rectifying plates (12b) and (12b) are arranged so as to face the intermediate portion of the height of the demister (7) from the rear or the front. (12a) It is farther from the demister (7) than the upper end of (12a). The lower ends of the second curved flow rectifying plates (12b) and (12b) are arranged so as to face the brine below the evaporation chamber (2) from above.

  The third curved rectifying plates (12c) (12c) near the front and rear side walls of the housing (1) are the widest and have a width approximately three times the width of the first curved rectifying plates (12a) (12a). And a horizontal part and a bent part formed at the end part on the side wall of the housing. The upper ends of the third curved rectifying plates (12c) and (12c) are arranged so as to face the upper end of the demister (7) from the rear or the front, but the second curved rectifying plates (12b) ) (12b) is farther from the demister (7) than the upper end. The lower ends of the third curved flow rectifying plates (12c) and (12c) are arranged so as to face the brine below the evaporation chamber (2) from above and slightly located near the front and rear side walls of the housing (1). ing.

According to the second modification, the three vertical rectifying plates (11a), (11b), and (11c) are omitted and the three curved rectifying plates (12a), (12b), and (12c) are omitted. Although the shape of is different from the case of the first modification, the water vapor generated in the lower part of the evaporation chamber (2) is guided by the three curved current plates (12a), (12b), and (12c), respectively, and then the vane type. The cross-sectional corrugated steam impingement plates (8) and (8) of the demister (7) pass through a zigzag gap (9) between them in the horizontal direction .

  Therefore, the curved rectifying plates (12a), (12b), and (12c) act to suppress the drift of the mist accompanying steam flowing into the vane type demister (7) installed in front of the condensing unit (3). Mist removal efficiency can be obtained. Moreover, it is possible to take a countermeasure against drift without significantly changing the structure of the multistage flash evaporator. In addition, since the curved rectifying plates (12a), (12b), and (12c) serve as mist scattering prevention plates, the mist load applied to the demister (7) can be reduced.

  Since the other points of the second modification are the same as those in the above embodiment, the same reference numerals are given to the same components in the drawings.

  Next, examples of the present invention will be described, but the present invention is not limited thereto.

  The multistage flash evaporator according to the present invention in which the vane type demister (7) according to the present invention shown in FIGS. 1 and 2 is applied to the first stage evaporator, and the conventional knitted braided wire demister (20 ) And a conventional multistage flash evaporator in which the conventional expanded wire mesh demister (21) shown in FIG. 9 was applied to the first stage evaporator, respectively, and a fresh water experiment was conducted for one year.

  The multistage flash evaporator of the present invention in which the vane type demister (7) (vane type mister eliminator) shown in FIGS. 1 and 2 is applied to the first stage evaporator, and the wire mesh demister (20) shown in FIGS. (21) With respect to the conventional multi-stage flash evaporator in which (wire mesh type mister eliminator 1 and 2) is applied to the first stage evaporator, the purity of the distilled water produced in the first stage of the evaporator (electric conductivity) was measured. .

  In the above multistage flash evaporator, the length of the housing (1) maintained in a decompressed state in the left-right direction is, for example, 20 meters, and 15 units of the housing (1) are provided in parallel in the front and rear. The length of the evaporation chamber of the housing (1) was 3.5 meters.

  As a result, in the multistage flash evaporator of the present invention in which the vane type demister (7) (vane type mister eliminator) is applied to the first stage evaporator, the purity of the produced distilled water (electric conductivity) deteriorates even after one year. It was found that scale deposition and deposition on the demister (7) was prevented. On the other hand, in the conventional multistage flash evaporator in which the wire mesh demisters (20) and (21) (wire mesh type mister eliminators 1 and 2) are applied to the first stage evaporator, the scale is deposited within half a year. It was found that the metal mesh demisters (20) and (21) were blocked by the accumulation, and the purity of the produced distilled water (electrical conductivity) deteriorated.

  In general, the demand for water resources is increasing due to abnormal weather, rapid industrial development, population growth, and improvement of living standards. Therefore, immediate response is desired in countries and regions where water resources are scarce. At present, as for seawater desalination equipment, a multistage flash evaporation method and a reverse osmosis membrane method are being compared in terms of system and cost. The present invention relates to a multistage flash evaporator of a seawater desalination apparatus using a multistage flash evaporation method, and contributes to the supply of inexpensive water resources.

DESCRIPTION OF SYMBOLS 1: Housing 2: Evaporating chamber 3: Condensing part 4: Drooping plate 5: Condensation tube bundle 6: Saddle-shaped condensate receptacle 7: Vane type demister 8: Cross-sectional corrugated vapor collision plate 9: Zigzag gap 10: Orifice 11 : Vertical rectifying plate 11a: first vertical rectifying plate 11b: second vertical rectifying plate 11c: third vertical rectifying plate 12: curved rectifying plate 12a: first curved rectifying plate 12b: second curved rectifying plate 12c: third curved rectifying plate Board 13: Weir (dam)

Claims (2)

It is equipped with a number of housings that are maintained under reduced pressure. Condensation tube bundles are provided at the top of each housing, and a bowl-shaped condensate receptacle is provided below the condensation tube bundles. A demister is provided in at least one of the steam inlets, and the lower part of the housing serves as an evaporation chamber and the upper part of the housing serves as a condensing chamber. Heated brine sequentially flows into the evaporation chambers of each housing through an orifice. In the multi-stage flash evaporator for flash evaporation, the demisters provided in the steam inflow portions on both sides of the front and rear of the condenser tube bundle in each housing are formed from a steam collision plate having a corrugated cross section arranged in parallel at a predetermined interval. The vane type demister is composed of a steam inflow portion on both the front and rear sides of the bundle of condensing tubes in each housing. Disposed Oite vertically zigzag gap between the steam impingement plate between the demister is formed in the horizontal direction, water vapor generated in the evaporation chamber the bottom of each housing, the cross-section waveform of the vane-type demister passes through the zigzag gap between the steam impingement plates are horizontally, during its passage, scale Lumpur component traces in water droplets (mist) contained in the water vapor, the wall surface of the cross-sectional waveform steam impingement plate It is characterized in that water vapor that has flowed down to the evaporation chamber side along the wall surface along with the adhering water droplets and passed through the zigzag gap between the vapor impingement plates of the vane type demister is in contact with the condensation tube bundle. Multistage flash evaporator. In the upper part of the evaporation chamber of each housing, there are provided a plurality of rectifying plates for guiding water vapor generated in the lower part of the evaporation chamber of the housing to a horizontal zigzag gap between the vapor collision plates of the vane type demister. The water vapor generated in the lower part of the evaporation chamber is guided by a plurality of flow straightening plates, and then horizontally passes through a zigzag gap between the corrugated vapor collision plates of the vane type demister. The multi-stage flash evaporator according to 1.

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