JPH0380901A - Method and apparatus for refining crystal - Google Patents

Abstract

PURPOSE:To improve the productivity in refining, promote the maintainability, and heighten the effect of refining by providing a transfer means to transfer crystals forcibly toward a hot melting section. CONSTITUTION:There are provided at one end of a vessel 1 a hot melting section 2 and a discharge port 3 for a melted liquid M1 which is melted in the section 2, while, at the other and thereof, a feed port 4 for crystal slurry M0, a discharge port 5 for reflux and mother liquor M2 having been used in refining and a transfer means 6 to forcibly transfer crystals from said other end toward one end in the vessel 1 are disposed. The crystals in the crystal slurry M0 fed from the port 5 of the refining apparatus 1 is forcibly moved by the means 6 so that the crystals are introduced into the melting section 2 to be melted on or near the surfaces thereof. Further, part of the melted liquid M1 is taken out as a product through the port 3, while part of the melted liquid is transferred as reflux liquid from one end of the other end of the vessel 1 to be countercurrently brought into contact with the moving crystals, while the crystals and mother liquor are taken out from the discharge port 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for purifying crystals of eutectic organic substances, etc., and an apparatus therefor.

[Conventional technology]

It may be required to melt and purify crystals of one component from a mother liquor of eutectic organics. For example, it is the melt purification of naphthalene, vala-xylene, vala-dichlorobenzene (PDCB), etc.

As this type of melt purification method, those described in Japanese Patent Publication No. 415733 and Japanese Patent Publication No. 54-34705 are known. In each of these prior examples, a heating melting section consisting of an electric heater is provided at the bottom of the purification tower, but the mother liquor and the crystals contained therein are adapted to move downward due to natural gravity settling.

[Problem to be solved by the invention]

However, in the conventional example, the mother liquor and the crystals contained therein move downward due to natural gravity sedimentation, so the productivity per unit time is extremely poor.

In addition, as shown in Fig. 5, the generated crystals do not settle to the base of the 9 groups of heating tubes installed in the lower part of the refining column 1 in the height direction, but instead connect the top levels of the 9 groups of heating tubes. A void or dead space D that causes a bridging phenomenon (the lower surface of the bridge is indicated by symbols B and r) and below which crystals do not migrate.
The crystals are often taken out from the outlet 3 without being purified. However, when such a bridging phenomenon occurs, the adhering crystals must be scraped off, which requires a great deal of maintenance and reduces the crystal purification effect.

Furthermore, inside the crystal bed B, the smooth 1
Since there is no downward movement, as shown in Figure 5,
A lump C of crystal is likely to be formed, and a space d is created below this lump C as the descent of the crystal is blocked by this lump C.At some point, the lump C suddenly falls, and during this fall, a space d is created. The air may suddenly rise and disturb the downward flow and reflux flow of the crystal, reducing the purification effect.

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide a method and apparatus for refining crystals, which significantly increases productivity during purification, is easy to maintain, and has a high purification effect.

[Means to solve the problem]

The method of the present invention for solving the above problems has a heating melting part for the crystals at one end in the container and an outlet for the melt melted by the heating melting part, and a crystal slurry at the other end. A supply port, a discharge port for the reflux liquid and mother liquor subjected to purification, and a moving means for forcibly moving the crystals from the other end side to the one end side inside the container, and the crystal slurry supply port and the reflux The discharge port for the liquid and mother liquor is formed using a refining device formed on the other end side of the moving means, and the crystals in the crystal slurry supplied from the supply port are forcibly moved by the moving means while heating one end. The crystals are melted on the surface of the melting zone or in the vicinity of the heated melting zone, and a part of the melt is taken out as a product from the outlet, while a part of the melt is passed from one end to the other as a reflux liquid. During this moving process, the crystals are brought into countercurrent contact with the crystals moving toward one end, and the crystals and mother liquor are taken out from the outlet.

Furthermore, the apparatus of the present invention has a heating melting section for crystals and an outlet for the melt melted by the heating melting section at one end of the container, and a supply port for crystal slurry and a refining port at the other end. The supply port for the crystal slurry and the discharge port for the reflux liquid and mother liquor are provided, and a moving means for forcibly moving the crystals from the other end side to the one end side inside the container. The present invention is characterized in that the outlet is formed closer to the other end than the moving means.

[Effect]

In the present invention, since the movement of the crystals is promoted by providing a moving means for forcibly moving the crystals toward the heated melting zone, the productivity per unit time is improved compared to the conventional natural gravity sedimentation. For example, as in the examples below, 6 to 8
It will increase twice as much.

Additionally, due to the forced movement of the crystals, the movement speed of the crystals is faster than in the case of natural settling of the crystals, and it is possible to prevent the crystals from adhering to the inner surface of the refining column or the aforementioned heating tube group, and forming bridging.
This allows continuous operation for long periods of time. Furthermore, it is possible to prevent blocking and uneven distribution of crystals inside the production bed to generate a uniform crystal bed, and to prevent disturbances in the movement of crystals and reflux liquid, which also improves the purification effect. can be increased.

[Specific structure of the invention]

The present invention will be explained in detail below with reference to specific examples shown in the drawings.

Note that the purification tower according to the present invention may be of a horizontal type as well as a vertical type, but the following description will mainly be based on an example of a vertical type.

Figure 1 shows an example of the apparatus of the present invention, in which 1 is a cylindrical refining tower serving as a vertical vessel, and a crystal heating and melting section 2 is located at the bottom of the column.
and an outlet 3 for the molten liquid M1 melted by the heating melting section 2.

Further, in the upper part of the purification tower 1, a supply port 4 for crystal slurry, a discharge port 5 for the mother liquor M2 subjected to purification, a moving means 6 for forcibly flowing the crystals in the crystal slurry downward, and In the example, it is equipped with a flow means.

Further, in the lower part of the purification tower I, an upper tube sheet 7 and a lower tube sheet 8 are vertically spaced apart to partition the inside of the tower, and from the upper tube sheet 7 to a large number of bottomed heating tubes 9, 9, . . . is installed protrudingly. On the other hand, a supply pipe 10 that is open vertically from the lower tube plate 8
．． 10 are provided protrudingly and inserted into the heating tube 9 at intervals. Furthermore, the lower tube plate 8 and the bottom plate I of the tower
A heating medium H0, for example, a hot water supply port 1, is connected to the heating medium H0.
1 is formed. Further, a discharge port 12 for the used heat medium H3 is formed in communication between the lower tube sheet 8 and the upper tube sheet 7. On the other hand, a screen 13 is provided at the middle in the height direction of the heating tube 9 via a support member 14, and between this screen 13 and the upper tube plate T, the above-mentioned outlet 3 is provided.
are communicating. The mesh of the screen 13 is sized so that it does not transmit any or very little through the target crystal.

On the other hand, a screen 15 is also disposed in front of the discharge port 5 at the upper part of the purification tower 1, and this mesh is also sized to not allow any or almost any target crystals to pass through.

Furthermore, a screw conveyor 6 is provided passing through the upper plate IA of the purification tower 1, and its shaft is attached to a seal box 16.
It is sealed by. This screw conveyor 6 is rotated by the output of a motor 17 via a reduction gear 18.

On the other hand, a bracket I9 is fixed to the upper plate IA, and a reciprocating cylinder 20 for vertical movement and a guide shaft 21 are vertically fixed to this bracket 19.

22 is a movable plate, and the rod tip of the cylinder 20 is fixed. It also holds the motor 17, the reducer 18, and the shaft of the screw conveyor 6. Further, a guide shaft 21 passes through the guide tube 21, and a guide tube 23 is held therein to guide the guide shaft.

In the refining apparatus configured in this manner, crystal slurry M0 containing crystals is supplied from the supply port 4. The crystals in the supplied crystal slurry are forcibly moved downward mainly by the rotation of the screw conveyor 6. As a result, the crystal bed B is below the lower end of the screw conveyor 6.
is generated.

The lower crystals in this crystal bed B contact the vicinity or surface of the heating tube 9 and melt. During this melting, impurities inside the crystal are eluted.

In addition, fine crystals are adsorbed around large crystals, causing recrystallization, and recrystallization occurs in a highly pure melt. Purification proceeds in this manner.

A part of the molten liquid accompanying the melting of the crystals is taken out of the system from the outlet 3 as a product. The molten liquid taken out is
It is crystallized by subsequent crystallization means or used as a product as it is.

In addition, another part of the melt rises as a reflux liquid. During this ascending process, it comes into countercurrent contact with the descending crystals, and reaches the upper part of the purification tower 1 while promoting purification of the crystals.While being mixed with the mother liquor, the spent mother liquor passes through the screen 15 and is discharged from the outlet 5. .

By the way, the screw conveyor 6 is rotated substantially continuously during the course of the refining operation, but it repeatedly descends and ascends. For example, the rod of the cylinder 20 is moved back and forth at a frequency of 0.1 to several tens of times per minute, preferably 0.2 to 7 times, thereby repeating the raising and lowering. Further, the vertical movement stroke S is preferably 10 to 150M.

By providing the screw conveyor 6, a crystal bed B is generated, and by consolidating this crystal bed B, the crystals in the lower part of the crystal bed B are transferred to the adjacent heating tube 9.9.
As a result, the formation of a bridge connecting the tops of adjacent heating tubes 9.9 and the generation of dead space D below the tops of the heating tubes 9.9, as in the conventional case, are prevented. Furthermore, uneven distribution of crystals, blocking, and generation of voids inside the crystal bed B in the column 1 can be prevented.

Further, by raising and lowering the screw conveyor 6, the supply of crystals to the heating melting section 2 becomes smoother than when the screw conveyor 6 is not raised and lowered. That is, if the screw conveyor 6 is simply rotated, the crystal bed B may become excessively compacted and hardened, and the crystals will not be smoothly transferred to the lower part, and bridging will occur as in the conventional case. Sometimes. On the other hand, raising and lowering the screw conveyor 6 has the effect of breaking the hardened crystal bed B, and as a result, the transition of the crystals to the heating tube 9 becomes smooth.

The vertical movement of the screw conveyor 6 is performed in correlation with the degree of consolidation of the crystal bed B, as described above. For example, as shown in FIG. 1, a torque detector 25 is provided on the drive shaft of the screw conveyor 6, and a detection target 2
6 and a position detector 27 for detecting the same are provided, and since the torque signal from the torque detector 25 is an index of the degree of consolidation of the crystal bed B, the torque signal is taken into a position controller 28 and the position controller 28 Accordingly, the lifting cylinder 2
0, control outputs such as the height direction position of the screw conveyor 6, the length of the vertical stroke, and the frequency of the vertical stroke can be given. In this case, the screw conveyor 6
The current position of is detected by a position detector such as "Magnescale" manufactured by Sony. The screw conveyor 6 can be moved up and down using a screw system as well as a cylinder.

Furthermore, when changing the position of the screw conveyor 6, the amount of crystal slurry supplied can be changed. for example,
When the screw conveyor 6 is raised, the amount of crystal slurry supplied can be increased, and vice versa.

In the present invention, the heating and melting part may be formed by an electric heater or the like in addition to the circulation of a heat medium. but,
If the heating melting means is arranged flat along the cross section of the container, the melting and refining effect will be low, so as in the example above, the heating melting section consisting of a group of heating tubes etc. is arranged along the axial direction of the container. is preferable. In addition, if there is a concern that crystals may adhere to the inner wall surface of the purification tower 1, a heating sheath 29 that passes steam or the like is installed on the outer wall surface, as shown in Fig. 1, to melt the crystals that are about to adhere. can be prevented.

In addition, in the present invention, the supply port 4 is not located at the upper end but at the second
As shown in the figure, it may be located in the middle (but above the lower end of the screw conveyor 6). In addition, in order to more reliably prevent uneven distribution of crystals inside the crystal bed B, and to ensure countercurrent contact between the descending crystals and the reflux liquid,
As shown in FIG. 2, stirring means, for example slowly rotating stirring blades 30, can be provided in the crystal bed B.

The drive source for the stirring blades 30 can be the same as the drive source for the screw conveyor 6.

On the other hand, when the screw conveyor 6 is used as a moving means, the consolidation force of the screw conveyor 6, in other words, the moving force, does not act sufficiently on the portion of the crystal bed B whose shaft portion is extended. Therefore, as shown in Figure 3, the screw conveyor 6
A partition cylinder 31 whose upper end is close to the lower end of the partition cylinder 31 is provided, and a heating pipe 9
If a group is provided and the crystal bed B is generated and heated and melted in the annular portion, the descent of the crystals and the rise of the reflux liquid are made uniform.

As a modification of the screw conveyor 6, a screw conveyor 6A having intermittent blades as shown in FIG. 4 can also be used. A plurality of moving means in the present invention may be provided within the purification tower.

In addition to the above-mentioned examples of eutectic organic substances, the present invention may also be directed to p-nitrochlorobenzene, styrene monomer, naphthalene and thionaphthalene as examples of solid solutions, or frozen concentrates such as juices and coffee. .

In the case of frozen concentrates, the low density of ice allows the device to be operated upside down. Further, the device of the present invention can be operated even if it is placed horizontally.

Although the detailed dimensions of the present invention are appropriately determined depending on the object, etc., it is generally preferable that the dimensions shown in FIG. 1 be 20 cb. It is also possible to provide a plurality of apparatuses of the present invention so that the upstream purification apparatus performs rough purification and the downstream purification apparatus performs precise purification.

On the other hand, the temperature difference between the heated melting zone and the upper part of the column 1 can be selected as appropriate depending on the target crystal system, but is 30°C.
Below, the temperature is particularly preferably 15°C or lower.

〔Example〕

The effects of the present invention will be explained below with reference to Examples.

(Example 1) A purification tower with a height of 1,500 mm and a cylindrical diameter of 250 mm was prepared, and a heating tube with a height of 400 mm and an outer diameter of 25 mm was installed at the bottom of the tower, and the heat transfer area of the heating tube group was 0.45 c/h and heated. A melting section was formed. In addition, we installed a screw conveyor whose blades are almost close to the inner surface of the tower, and adjusted the rotation speed of the screw conveyor so that the degree of consolidation of the crystal bed was constant, and moved it up and down at a frequency of 20 times/min with a stroke of 10 mm. The crystal slurry was supplied so that the level of the crystal bed remained constant.

As this mother liquor, p-xylene 85%, 0-xylene 1
A material containing p-xylene crystals having a composition of 5% is supplied, the temperature of the heating melting part is 13 ° C., the upper temperature is 7 ° C.,
The reflux ratio was operated to be 0.2.

As a result, p-xylene with a purity of 99.90% was produced at 160%
kg/hr.

(Comparative Example I) In Example 1, the operation was performed under the same conditions except that the screw conveyor was not moved up and down.

As a result, the purity was the same, but the production amount was 2.
It was extremely low at 3 kg/hr.

(Example 2) The apparatus was the same, but a mother liquor containing p-dichlorobenzene crystals with a composition of 70% p-dichlorobenzene and 30% 0-dichlorobenzene was used, and the reflux ratio was It was operated in the same manner as in Example t, except that the temperature was changed to 0.3.

As a result, p-dichlorobenzene with a purity of 99.92% could be obtained at a production rate of 245 kg/hr.

(Comparative Example 2) Operation was carried out under the same conditions as in Example 2, except that the amount of heat medium supplied to the heating and melting zone was reduced and reflux was not performed.

As a result, the purity decreased to 97.0%.

(Comparative Example 3) Operation was carried out under the same conditions as in Example 2 except that the screw conveyor was not operated.

As a result, the purity was almost the same, but the production amount was 3.5
kg/hr.

(Example 3) The same operation as in Example 1 was carried out by supplying a crystal slurry containing naphthalene having a composition of 90% naphthalene and 20% thionaphthalene, and setting the reflux ratio to 0.2.

As a result, naphthalene with a purity of 99% could be obtained at a production rate of 95 kg/hr. Note that the temperature of the melting zone was 79.5°C.

(Example 4) The apparatus of Example 1 was turned upside down, a crystal slurry containing ice crystals with a composition of 15% salt and 85% water was supplied, and the reflux ratio was set to 0.2, and the same procedure as in Example 1 was carried out. performed the operation.

As a result, water with a purity of 99.9% could be obtained at a production rate of 500 kg/hr. In this case, the temperature of the upper melting zone was 0°C.

〔Effect of the invention〕

As described above, according to the present invention, the productivity in purification is significantly increased, the maintainability is excellent, and the purification effect is high.

[Brief explanation of drawings]

1 to 3 are schematic vertical sectional views of the first to third embodiments of the apparatus of the present invention, FIG. 4 is a front view of main parts of a modified example of the screw conveyor, and FIG. 5 is a conventional example of the present invention. FIG. 3 is a longitudinal cross-sectional view shown in relation to the device. 1... Purification tower, 2... Heating melting section, 3... Output port, 4... Supply port, 5... Discharge port, 6.6A... Screw conveyor, 9... Heating Tube, 13.15...
Screen, 17...Motor, 20...Cylinder, M. ...crystal slurry, Ml...melt liquid, M,...
... Spent mother liquor, H, ... Heat medium. Figure 4

Claims (8)

[Claims] (1) One end of the container has a heating melting section for crystals and an outlet for the melt melted by the heating melting section, and the other end has a supply port for crystal slurry and a reflux liquid used for purification. a discharge port for the mother liquor, and a moving means for forcibly moving the crystals from the other end side to the one end side within the container, and the supply port for the crystal slurry and the discharge port for the reflux liquid and the mother liquor are provided for the movement means. Using a refining device formed on the other end side of the means,
The crystals in the crystal slurry supplied from the supply port are forcibly moved by the moving means and guided to the heating melting section at one end, and the crystals are melted on or near the surface of the heating melting section, and the molten liquid is While a part of the melt is taken out as a product from the outlet, a part of the melt is moved as a reflux liquid from one end to the other, and in this movement process, it is countercurrently moved with the crystals moving towards one end. A method for purifying crystals of a eutectic organic substance, which comprises bringing the crystals into contact with the mother liquor and taking out the crystals and the mother liquor from the outlet. (2) The method according to claim 1, wherein the moving means comprises a screw conveyor arranged along the axial direction of the container, and the screw portion of the screw conveyor repeatedly moves in the axial direction during the refining operation. (3) During the refining operation, the moving means adjusts the position of the moving means in the axial direction of the container according to the degree of consolidation of the crystal bed generated on the one end side from the tip of the moving means, and adjusts the position of the moving means in the container axial direction. 2. The method according to claim 1, wherein the amount of crystal slurry supplied is adjusted accordingly. (4) One end of the container has a crystal heating melting section and an outlet for the melt melted by the heating melting section, and the other end has a crystal slurry supply port and a reflux liquid used for purification. a discharge port for the mother liquor, and a moving means for forcibly moving the crystals from the other end side to the one end side within the container, and the supply port for the crystal slurry and the discharge port for the reflux liquid and the mother liquor are provided for the movement means. A crystal refining device characterized in that the device is formed closer to the other end than the means. (5) The refining device according to claim 4, wherein the moving means comprises a screw conveyor arranged in the axial direction of the container, and further includes a cylinder for moving the screw conveyor in the axial direction. (6) The moving means consists of a screw conveyor disposed on the other end side in the axial direction of the container, and a partition cylinder having approximately the same diameter as the shaft diameter of the screw conveyor extends from the one end to near the tip of the screw conveyor. 5. The refining device according to claim 4, wherein the heating melting section is provided on the one end side of the annular portion between the partition tube and the inner surface of the container. (7) The purification apparatus according to claim 4, wherein the heating and melting section comprises a group of heating tubes arranged in the axial direction of the container. (8) The apparatus according to claim 4, wherein stirring means is provided inside the crystal bed generation region between the moving means and the heating melting section.