JP2004154619A - Circulation and scrape-off type crystallizer for forming crystals from liquid to be treated - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circulation and scrape-off type crystallizer for forming chrystals from a liquid to be treated capable of largely growing crystals while preventing the abrasion, crushing or the like of crystals and capable of reducing fine crystals. <P>SOLUTION: The circulation and scrape-off type crystallizer for forming crystals from a liquid to be treated is equipped with a crystallizing tank 6, a draft tube 7, an outside rotary blade 8, scrape-off blades 9 rotated around a peripheral wall shaft to scrape off the crystals adhering to the inner surface 3A of a peripheral wall 3 and a revolution suppressing plate 10 for the liquid P to be treated extending from a bottom material 4 toward the peripheral wall shaft. An inside rotary blade 12 for promoting the liquid P to be treated toward the revolution suppressing plate 10 is provided to the inside lower end part of the draft tube 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scraping type crystallization apparatus that circulates a liquid to be treated.
[0002]
[Prior art]
Conventionally, crystallization methods include, for example, an adiabatic cooling method, a direct cooling method by blowing refrigerant, an indirect cooling method using a jacket or a heat exchanger, an evaporative concentration method, and a salting-out method. These crystallization methods are appropriately selected and used depending on the characteristics of the crystal, the relationship with the pre- and post-processes, economic efficiency, and the like.
[0003]
In addition, in order to avoid the drawback of "indirect cooling method, in which crystals adhere to the cooling surface to lower the heat transfer coefficient and reduce operability," a new stock solution is supplied or once the cooling surface is used. Is used to dissolve the crystals attached to the cooling surface by heating (batch type), or to scrape the crystals attached to the cooling surface with a scraper (so-called scraper) (scraping type). However, in the batch type indirect cooling method, an operation problem occurs when the throughput increases, and in reality, the scraping type indirect cooling method is generally used.
[0004]
FIG. 1 shows an example of a crystallization apparatus using this indirect cooling method of the scraping type.
That is, a crystallization tank 105 having a cylindrical peripheral wall 101 and a bottom member 104 to which the liquid P to be treated is supplied, a draft tube 102 provided in the crystallization tank 105, and an inside of the draft tube 102 A liquid circulation type scraper having an inner rotating blade 103 provided, and a not-shown scraping blade (scraping blade) that rotates around the axis of the surrounding wall 101 and scrapes crystals attached to the inner wall surface 101A of the surrounding wall 101. It is a precipitating crystallizer 100 (the symbol M in the figure is a driving device such as a motor for rotating the inner rotating blade 103. In this device 100, a scraping blade not shown is a driving device such as this. M was driven by another driving device.)
[0005]
However, since the crystallization apparatus 100 has a problem of abrasion and crushing of the crystal due to the high-speed rotation of the inner rotating blade 103, a rotating blade 206 as shown in FIG. A crystallization apparatus 200 in a provided form has been proposed and used (note that 201 is a peripheral wall, 201A is an inner wall surface of the peripheral wall, 204 is a bottom material, and 205 is a crystallization tank. Some devices M rotate not-shown scraping blades in addition to the outer rotating blades 206.) In order to further improve the circulation of the liquid P to be processed, the apparatus 200 further includes a rotation suppressing plate 207 that further suppresses the rotation of the liquid P that has been swirled by the rotating blades 206 and changes the circulation direction to upstream and downstream. (For example, see Patent Document 1).
[0006]
The crystallization apparatus 200 is very useful because it prevents the crushing of the crystals and the rotation of the liquid to be treated.
[Patent Document 1]
JP-B-61-25402 (Fig. 1)
[0007]
[Problems to be solved by the invention]
However, in recent years, a crystallizer capable of growing crystals larger and reducing the number of fine crystals has been required, and further improvement of the crystallizer is expected. Of course, it is conceivable that the crystal may grow larger by increasing the rotation speed of the rotating blades to generate a large circulating flow. However, in this case, the abrasion and crushing of the crystal are likely to occur, and the advantage of such a device is reduced. Will be done.
[0008]
Therefore, a main object of the present invention is to provide a liquid circulation type scraping-type crystallizer capable of growing a large crystal and reducing the number of fine crystals while preventing abrasion and crushing of the crystal. Is to provide.
[0009]
[Means for Solving the Problems]
The present invention which has solved the above-mentioned problems is as follows.
<Invention according to claim 1>
A crystallization tank having a cylindrical peripheral wall and a bottom material, to which the liquid to be treated is supplied; a draft tube provided in the crystallization tank; and an outer rotating blade provided outside the draft tube; A scraper blade that rotates about the peripheral wall axis and scrapes crystals attached to the inner surface of the peripheral wall, and at least one swirl suppressing plate for the liquid to be treated that extends from the bottom material in the axial direction of the peripheral wall. ,
A liquid-to-be-treated circulation-type scraping-type crystallization apparatus, wherein the liquid to be treated is circulated by the rotation of the outer rotating blades, whereby the liquid to be treated rises outside the draft tube and descends inside the draft tube. ,
A liquid-to-be-processed-type scraping-type crystallization apparatus, wherein an inner rotating blade that propels the liquid to be processed toward the turning control plate is provided at an inner lower end portion of the draft tube.
[0010]
<Invention according to claim 2>
A crystallization tank having a cylindrical peripheral wall and a bottom material, to which the liquid to be treated is supplied; a draft tube provided in the crystallization tank; and an outer rotating blade provided outside the draft tube; A scraper blade that rotates about the peripheral wall axis and scrapes crystals attached to the inner surface of the peripheral wall, and at least one swirl suppressing plate for the liquid to be treated that extends from the bottom material in the axial direction of the peripheral wall. ,
A liquid-to-be-treated circulation-type scraping-type crystallization apparatus, wherein the liquid to be treated is circulated by the rotation of the outer rotating blades, whereby the liquid to be treated rises outside the draft tube and descends inside the draft tube. ,
Wherein the outer rotating blades are provided at an outer lower end portion of the draft tube, and are configured to suck up the liquid to be processed, the rotation of which is suppressed by the rotation suppressing plate. Type crystallizer.
[0011]
<Invention of Claim 3>
3. The scraping crystallization apparatus according to claim 1, further comprising at least one plate for suppressing rotation of the liquid to be processed extending from the ceiling material in the axial direction of the peripheral wall.
[0012]
<Invention of Claim 4>
4. The circulation of the liquid to be treated according to claim 1, wherein a conical protrusion is provided at the center of the bottom material, and crystal block crushing means is provided on the bottom material other than the protrusion. 5. Type scraping crystallizer.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. The liquid to be treated according to the present invention refers to, for example, a slurry-like solution in which a crystalline substance such as paradichlorobenzene, bisphenol A, or 2,6-dimethylnaphthalene is dissolved. Not done.
[0014]
(Entire device)
As shown in FIGS. 3 and 4, the liquid-to-be-processed scraping-type crystallization apparatus 1 of the present embodiment has a peripheral wall 3, a bottom material 4, and a top material 5, and is supplied with the liquid-to-be-processed P. The crystallization tank 6, a draft tube 7 provided in the crystallization tank 6, an outer rotating blade 8 provided outside the draft tube 7, and an inner wall 3 </ b> A of the peripheral wall 3 which is rotated around three axes of the peripheral wall. .., And at least one, in this embodiment, three rotation suppressing plates 10 for the liquid P to be treated, which extend in three axial directions from the bottom member 4 in the present embodiment. (Hereinafter, also simply referred to as the lower turning suppression plate 10), and at least one, in this embodiment, three turning suppression plates 11 for the liquid P to be processed, extending in the three axial directions from the top material 5. (Hereinafter also simply referred to as the upper turning control plate 11).
[0015]
The peripheral wall 3 of the crystallization tank 6 has a cylindrical shape, and the lower end edge of the peripheral wall 3 is connected to the bottom material 4 and the upper end edge thereof is connected to the ceiling material 5. The bottom member 4 and the top member 5 may be formed integrally with the peripheral wall 3 or may be formed as separate members from the peripheral wall 3. In the present embodiment, both the bottom member 4 and the top member 5 are formed as separate members from the peripheral wall 3. The top material 5 is provided with a liquid supply port 15, and the bottom material 4 is provided with two liquid discharge ports 16, 16.
[0016]
An outer jacket 17 is provided on the peripheral wall 3 of the crystallization tank 6 so as to surround the same. Refrigerant is passed through the outer jacket 17 via a refrigerant supply / discharge port 17A, whereby the liquid P to be treated in the crystallization tank 6 is indirectly cooled.
[0017]
The draft tube 7 is disposed coaxially with the peripheral wall 3 and at a position separated from the bottom member 4. The draft tube 7 is attached to a shaft 19 via bar-shaped support spokes 18 extending in the horizontal direction. The shaft 19 is arranged at the axis of the peripheral wall 3 so as to extend in the vertical direction, and is supported by a bearing 20. When the shaft 19 is rotated by a motor M which is a driving device attached to the upper part of the heavenly material 5, the draft tube 7 is also rotated in accordance with the rotation (the device 1 is driven by the motor M via the uniaxial shaft 19). Therefore, the mechanical structure in which all of the scraping blade 9, the outer rotating blade 8 and the inner rotating blade 12 are rotated is not complicated.)
[0018]
An outer rotating blade 8 is provided at an outer lower end of the draft tube 7. Due to the rotation of the outer rotating blades 8, the liquid P to be processed circulates upward on the outside of the draft tube 7 and descends on the inside thereof. This circulation promotes crystal growth. The method of providing the outer rotating blades 8 is not particularly limited. For example, as in the present embodiment, it can be attached to the outer wall surface of the draft tube 7 or can be attached to the shaft 19 via a rod-shaped support spoke (18) (of course, it does not collide with other members). is necessary.). However, from the viewpoint of preventing the rotation of the liquid P to be treated, it is preferable that the liquid P is directly attached to the draft tube 7 without using a support spoke or the like.
[0019]
In the present invention, unlike the conventional configuration in which the outer rotating blades are provided at the outer central portion of the draft tube, the outer rotating blades are provided at the outer lower end portion of the draft tube. That's why. In other words, the liquid to be treated whose circulation speed has decreased due to the contact with the swirl suppressing plate is rounded up, and the circulation speed is recovered, thereby maintaining a suitable circulation. When the liquid to be treated circulates regularly, the growth of crystals proceeds effectively, and the supersaturation in the crystallization tank becomes uniform, preventing the local supersaturation from increasing. Can be
[0020]
In the present embodiment, an inner rotating blade 12 is further provided at an inner lower end of the draft tube 7. The method of providing the inner rotating blades 12 is not particularly limited. For example, as in the present embodiment, the base end may be attached to the shaft 19 and the tip end may be attached to the inner wall surface of the draft tube 7, or the base end may be attached to the shaft 19. However, the distal end portion may not be attached to the inner wall surface of the draft tube 7. However, if both the base end and the front end are attached (former form), the inner rotating blade 12 can have the same function as the above-described support spokes 18, 18,.
[0021]
In the present invention, unlike the conventional embodiment in which the inner rotating blade is not provided, the inner rotating blade is provided at the inner lower end portion of the draft tube in order to propel the liquid to be processed toward the swirl suppressing plate. By this propulsion, it is possible to prevent the liquid to be treated from hitting the swirl suppressing plate and lowering its circulation speed as much as possible. In other words, by slightly increasing the circulation speed of the liquid to be processed before hitting the swirl control plate, the circulation speed in the vicinity of the swirl control plate becomes the same as the circulation speed in the other parts, and therefore, the liquid to be processed is in the vicinity of the swirl control plate. And turbulence can be prevented.
[0022]
Note that the inner rotating blades merely serve as an auxiliary role of adjusting the flow in circulating the entire liquid to be treated (passive action). Therefore, abrasion and crushing of the crystal do not occur.
[0023]
The range of the “lower end” of the draft tube provided with the outer rotating blades and the inner rotating blades is determined by the rotation speed, diameter, area, properties of the liquid to be treated, diameter of the peripheral wall, diameter of the draft tube, and the like. Therefore, it is set appropriately within a range in which the abrasion / crushing of the crystal does not occur (when the rotation speed is high, the range of the lower end portion is widened, but the abrasion / crushing of the crystal increases). In the present embodiment, the outer rotating blades 8 are provided at the same height position as the swirl suppressing plate 10, and the inner rotating blades 12 are provided slightly above.
[0024]
By the way, when the swirling flow of the liquid P to be treated is mainly used, the ratio of the liquid P to be cooled cooled near the peripheral wall 3 to the inside of the draft tube 7 decreases, and the ratio between the inside of the draft tube 7 and the vicinity of the peripheral wall 3 is reduced. There is a temperature gradient between the two. Therefore, in the vicinity of the peripheral wall 3, the temperature difference between the liquid P to be treated and the refrigerant is reduced, and the heat transfer coefficient is reduced. Further, the degree of supersaturation in the crystallization tank 6 becomes non-uniform, and microcrystals are easily generated. In addition, there is a problem that the crystals adhere to and precipitate on the scraping blades (scraping blades) to stop the operation, and the crystals settle at the lower side of the crystallization tank 6, and the contact between the supersaturated mother liquor and the crystals becomes poor. Therefore, the lower swirl suppressing plate 10 is provided to convert the swirling flow of the liquid P to be processed to upstream and downstream. Therefore, the shape and the mounting position are not particularly limited, and the design can be appropriately changed. In the present embodiment, as shown in FIG. 4, the shape of the lower turning suppression plate 10 is substantially arcuate in cross section (a state in which the processing target liquid P expands in the horizontal flow direction). When the cross section is substantially arcuate, the swirling flow can be reliably received, and an effective upstream / downstream conversion can be achieved. Also, the mounting position of the lower-side turning restraint plate 10 is such that the distal end (extended length) is located at the lower end of the draft tube 7 in the up-down direction so as to be located inside the draft tube 7 in the horizontal direction. It is in a state of being intruded. The reason that the lower turning control plate 10 is inserted into the lower end portion of the draft tube 7 is to prevent the swirling flow from passing through the side of the lower turning control plate 10 and preventing the turning from being disabled. It is.
[0025]
Like the lower turning control plate 10, the upper turning suppression plate 11 is also for converting the swirling flow of the liquid P to be processed into upstream and downstream. Therefore, the shape and the mounting position are not particularly limited, and the design can be appropriately changed. In the present embodiment, as shown in FIG. 4, the shape of the upper turning control plate 11 has a substantially arcuate cross section (a state swelling in the flow direction of the liquid P to be treated). In addition, the mounting position of the upper turning restraint plate 11 extends from the outer position to the slightly inner position of the draft tube 7 in the horizontal direction. 7 is slightly higher than the upper edge.
[0026]
In this embodiment, the scraping blades 9 are attached to the outer wall surface of the draft tube 7. For example, the support spokes (18) can be attached to the shaft 19 via rod-shaped support spokes (18) or the like, or the support spokes (18) can be provided with a flat bar extending vertically and attached to the flat bar. When it is directly attached to the outer wall surface of the draft tube 7 as in the embodiment, it is possible to prevent the swirling flow of the liquid P to be processed due to the rotation of the support spoke, which is preferable. The shape and mounting position of the scraping blades 9, 9 are not particularly limited. For example, a single rod-shaped member extending from the lower end position to the upper end position of the peripheral wall 3 may be used. However, as in the present embodiment, the scraping blade groups 9A and 9B are provided at positions facing each other in the horizontal direction, and the scraping blades 9, 9... Of the scraping blade group 9A and the scraping blades 9B of the scraping blade group 9B are scraped. It is preferable that the blades 9, 9,... Are provided so as to be shifted from each other in the vertical direction. By providing the scraping blades 9, 9 in this manner, an upward circulating flow can be generated (for example, a single blade extending from the lower end position of the peripheral wall 3 to the upper end position of the peripheral wall 3). In this case, no upward circulating flow is generated.) Also, a small driving force for rotating the shaft 19 is sufficient.
[0027]
The crystals attached to the inner wall surface 3A of the peripheral wall 3 are scraped off by the above-mentioned scraping blades 9, 9,... And float in the liquid P to be treated to form a slurry. Also, it has been confirmed by an experimental machine that the radial length of the scraping blades 9, 9,... Is preferably not more than 3/100 of the diameter of the crystallization tank.
[0028]
By the way, in the crystallization tank 6, crystals attached to the inner wall surface of the peripheral wall 3 and the shaft 19 may fall and form a crystal block. In the case of a conventional conical bottom material having a low central portion, since the blocks are concentrated in the central portion, even if a crushing mechanism of the crystal block is provided, it is possible to completely eliminate the blockage trouble at the time of extracting the liquid to be treated. Was difficult. However, a conical protruding portion is provided at the center of the bottom member 4 (the protruding portion includes one in which the bottom member 4 itself protrudes and one in which another member is attached), and this protruding portion. By attaching the crystal block crushing means 21 on the bottom material 4 other than the portion, the crystal blocks gather outside (on the side of the peripheral wall 3), so that the crystal blocks can be loosened. Therefore, the blockage trouble at the time of extracting the slurry can be eliminated. As shown in an enlarged manner in FIG. 3, the crushing means 21 according to the present embodiment includes convex portions 21A, 21A,... Mounted on the bottom member 4, and a draft tube meshing with the convex portions 21A, 21A,. 7 are formed in a comb shape by convex portions 21B, 21B,.
[0029]
【The invention's effect】
As described above, according to the present invention, while preventing abrasion and crushing of the crystal, it is possible to grow the crystal large and to reduce the number of fine crystals. Device.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a conventional crystallization apparatus.
FIG. 2 is an explanatory view of a conventional crystallization apparatus.
FIG. 3 is a longitudinal sectional view of the crystallization apparatus of the present embodiment.
FIG. 4 is a cross-sectional view of the crystallization apparatus of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Crystallizer, 3 ... Peripheral wall, 4 ... Bottom material, 5 ... Top material, 6 ... Crystallization tank, 7 ... Draft tube, 8 ... Outer rotating blade, 9 ... Scrape blade, 10 ... Lower turning suppression plate Reference numeral 11 denotes an upper rotation suppressing plate, 12 denotes an inner rotating blade, 15 denotes a liquid to be processed, 16 denotes a liquid to be processed, 17 denotes an outer jacket, 19 denotes a shaft, 20 denotes a crushing mechanism, and P denotes a liquid to be processed.

Claims (4)

A crystallization tank having a cylindrical peripheral wall and a bottom material, to which the liquid to be treated is supplied; a draft tube provided in the crystallization tank; and an outer rotating blade provided outside the draft tube; A scraper blade that rotates about the peripheral wall axis and scrapes crystals attached to the inner surface of the peripheral wall, and at least one swirl suppressing plate for the liquid to be treated that extends from the bottom material in the axial direction of the peripheral wall. ,
A liquid-to-be-treated circulation-type scraping-type crystallization apparatus, wherein the liquid to be treated is circulated by the rotation of the outer rotating blades, whereby the liquid to be treated rises outside the draft tube and descends inside the draft tube. ,
A liquid-to-be-processed-type scraping-type crystallization apparatus, wherein an inner rotating blade that propels the liquid to be processed toward the turning control plate is provided at an inner lower end portion of the draft tube. A crystallization tank having a cylindrical peripheral wall and a bottom material, to which the liquid to be treated is supplied; a draft tube provided in the crystallization tank; and an outer rotating blade provided outside the draft tube; A scraper blade that rotates about the peripheral wall axis and scrapes crystals attached to the inner surface of the peripheral wall, and at least one swirl suppressing plate for the liquid to be treated that extends from the bottom material in the axial direction of the peripheral wall. ,
A liquid-to-be-treated circulation-type scraping-type crystallization apparatus, wherein the liquid to be treated is circulated by the rotation of the outer rotating blades, whereby the liquid to be treated rises outside the draft tube and descends inside the draft tube. ,
Wherein the outer rotating blades are provided at an outer lower end portion of the draft tube, and are configured to suck up the liquid to be processed, the rotation of which is suppressed by the rotation suppressing plate. Type crystallizer. 3. The scraping crystallization apparatus according to claim 1, further comprising at least one plate for suppressing rotation of the liquid to be processed extending from the ceiling material in the axial direction of the peripheral wall. 4. The circulation of the liquid to be treated according to claim 1, wherein a conical protrusion is provided at the center of the bottom material, and crystal block crushing means is provided on the bottom material other than the protrusion. 5. Type scraping crystallizer.

Images