JP4086257B2 - Tower-type crystallizer with inclined refining section - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a novel crystallizer, and more particularly to a columnar crystallizer having a gradient purification unit that can be used in a field where a high degree of separation and purification is required.
[0002]
[Prior art]
In recent years, the demand for advanced separation / purification has increased, and purification by crystallization for that purpose has been demanded on an industrial scale.
Various crystallization towers for purification purposes (column-type crystallization apparatuses having a concentration and temperature distribution in the axial direction in the apparatus) are known. In many of these crystallization towers, the gravity settled crystal particles are brought into countercurrent contact with the reflux liquid to increase the purification efficiency. Therefore, separation and purification has been considered difficult in systems where the density difference between solid and liquid is small.
Crystallization towers have been developed for the purpose of purifying organic substances, but in the case of organic substance solutions, the difference in density between solid and liquid is generally small, so the use of crystallization towers is limited and good crystal particles It is difficult to obtain (spherical and large particle size particles).
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a column type crystallization apparatus suitable for high-purification based on a completely different principle from a conventional crystallization column.
[0004]
[Means for Solving the Problems]
The present invention provides a crystallization apparatus having at least a purification section and a crystallization section, wherein at least the purification section is inclined with respect to a vertical line.
[0005]
The refining section is preferably inclined at a maximum of 60 degrees from the vertical line. If the inclination angle exceeds 60 degrees, an increase in the sedimentation rate of the crystal particles cannot be expected, which is not preferable. In the present invention, the inclination angle θ from the vertical line must not be zero. The inclination angle θ is preferably selected from 20 to 60 degrees depending on the type of liquid to be treated and the dimensions of the apparatus.
[0006]
In one embodiment of the present invention, the purification section comprises a hollow housing having a crystal recovery section at the bottom. The inner cross-sectional shape of the hollow housing is preferably circular, but may be a polygon such as a quadrangle.
[0007]
It is preferable to provide means for scraping off crystals adhering to the inner wall of the hollow housing. In the case of a hollow housing having a circular cross section, a rotary scraper can be used as scraping means. The rotating scraper must be rotated at a low speed that does not adversely affect the crystallization operation. As the scraping means, any known mechanism other than the rotary scraper can be used.
[0008]
In a preferred embodiment of the present invention, the purification section and the crystallization section are constituted by a single hollow housing, and a supply portion for the liquid to be treated is provided between the purification section and the crystallization section. In another embodiment of the present invention, the crystallization part is provided separately, and the slurry coming from the crystallization part is supplied to the upper part of the purification part.
[0009]
[Action]
A crystal particle group (low density difference, small particle size, non-granularity) having a slow sedimentation rate is difficult to form a dense layer of crystal particle groups. This is made more difficult by the presence of rising reflux. By inclining the crystallizer wall with respect to the vertical line, the present inventor uses the so-called principle of the inclined plate settling tank, and separates the settling particles from the rising flow of the exclusion liquid as described above. I thought about solving the shortcomings.
[0010]
On the other hand, the inclined tower increases the sedimentation speed, but the countercurrent contact action between the solid and the liquid decreases. Therefore, in the present invention, it is preferable to maintain good contact by gently stirring the slurry in the tower. Stirring for this purpose can be simultaneously performed by a rotary scraper that performs a scraping operation of the inner wall.
[0011]
In the crystallization apparatus of the present invention, the entire crystallization tower or the refined part thereof is inclined to promote the precipitation of the crystal particle group, and the liquid and the crystal group are gently mixed to make good contact between the solid and the liquid. . As a result, efficient purification is performed.
[0012]
Hereinafter, the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing the principle of the present invention. In this crystallizing apparatus, a housing 1 is disposed with an inclination of θ with respect to a vertical line. This θ is 60 degrees at the maximum. The substantially lower half 2 of the housing 1 serves as a purification part, and the substantially upper half 3 constitutes a crystallization part. The liquid to be treated 4 is supplied from an intermediate part between the purification unit 2 and the crystallization unit 3, and the obtained crystal 5 is extracted from the bottom of the housing 1, and the exclusion liquid 6 overflows from the upper edge of the housing 1.
[0013]
FIG. 2 is a conceptual cross-sectional view of a crystallization apparatus used in a preliminary experiment conducted to confirm the effect of the present invention. This preliminary experiment is for observing crystal growth from the outside by using a transparent glass tube 1 in total reflux operation (no supply / discharge). The bottom of the glass tube 1 is closed with a plug 26. A heater 25 is wound around the protrusion formed at the inner center of 26. A cooling jacket 3 a is wound around the upper portion of the glass tube 1, and the rotating scraper 7 is rotatably supported inside the glass tube 1.
[0014]
FIG. 3 is a conceptual cross-sectional view of one embodiment of the crystallization apparatus of the present invention. In this crystallization apparatus, a temperature control jacket 3a is attached to the upper portion of the housing 1 constituting the crystallization section, and the purification is performed. A melting heater 2 a is attached to the lower end portion of the housing 1 constituting the portion 2. A rotating scraper 7 for scraping off crystals adhering to the inner wall of the housing 1 is rotatably supported in the housing 1 by appropriate means (not shown). The supply / discharge (4, 5, 6) of the liquid is performed according to the principle diagram of the present invention shown in FIG. The rotating scraper 7 does not collide with the supply pipe 4. The illustrated rotary scraper 7 is attached in a staggered manner along the axial direction of the rotating shaft of the rod extending radially from the rotating shaft, and a spatula for scraping the entire inner wall of the housing 1 is attached to the tip of each rod.
[0015]
The shape of the rotary scraper 7 is not limited to this, and can be variously selected depending on the type of liquid to be treated, the size of the crystallizer, and the like. For example, a spiral scraper in which a spiral ribbon or a spiral wire is sequentially supported at the tip of each rod can be used. In any case, it is important that the rotating scraper 7 does not adversely affect the precipitation of crystal particles and the rise of the reflux liquid in the housing 1.
[0016]
FIG. 4 is a modification of FIG. 3 in which the crystallization part of FIG. In this case, the liquid to be treated 4 "is supplied to an arbitrary crystallization tank 8 equipped with a simple stirrer, and a solution 10 containing crystal particles generated (grown) in the crystallization tank 8 is supplied to the supply pipe 4 It is supplied to the upper part of the housing 1 through “.” The exclusion liquid 6 is provided above the position of this supply pipe 4 ′.
[0017]
FIG. 5 shows another modification of FIG. 3. In this embodiment, the liquid to be treated 23 is supplied through an internal supply pipe coaxial with the rotary shaft 21 and sent into the housing 11 through the supply port 22. In the figure, reference numeral 24 denotes a blade attached to the rotary shaft 21 constituting the rotary scraper, 40 is a crystal recovery port, and 50 is a drainage overflow port.
FIG. 6 is a conceptual diagram when the unit units of FIG. 5 are arranged in parallel.
[0018]
【Example】
Example 1
An experiment for recovering ε-caprolactam crystals from the ε-caprolactam-water system was performed using the preliminary experimental apparatus shown in FIG.
A glass cylinder having a diameter of 5 cm and a height of 100 cm was used as a crystallization tower. A temperature control jacket was attached to the upper half of the glass cylinder, and water was supplied from a thermostatic bath to maintain a constant temperature (becomes a crystallization part). A melting heater was inserted into the lower end of the glass cylinder. The lower half of the glass cylinder is the purification section. A rotating scraper having wings for scraping off crystals adhering to the inner wall was placed in the glass cylinder and rotated at a low speed at a predetermined speed.
The glass cylinder was installed with an inclination of 27 ° with respect to the vertical line.
[0019]
An ε-caprolactam-water mixture having an ε-caprolactam concentration of 96% by weight was charged in a substantially middle portion of a glass cylinder and observed under the following conditions under total reflux:
Water temperature for temperature control 45 ℃
Liquid temperature of heater section 65 ℃
Rotating shaft rotation speed 0.05 rev / sec 【0020】
When observed from outside the glass cylinder, sedimentation of the crystal particles was observed, and the reflux liquid was observed to rise along the upper surface of the glass cylinder from the lower end. When the crystals obtained after the total reflux for about 10 hours were extracted from the lower end of the glass cylinder and observed with a microscope, the crystals were good spherical and large-diameter crystal particles.
[0021]
Comparative Example 1
The example was repeated but the glass cylinder was 0 ° (ie not tilted) with respect to the vertical line.
In this case, the crystal particles generated (grown) at the upper end are fine and hardly settle. In addition, the reflux liquid was observed to rise with crystal particles, and good separation was not performed.
The crystals obtained after continuous operation for the same time as in Example 1 are fine and small in quantity.
[0022]
【The invention's effect】
In the crystallization apparatus of the present invention, the entire crystallization tower or the refined part thereof is inclined to promote the precipitation of the crystal particle group, and the liquid and the crystal group are gently mixed to make good contact between the solid and the liquid. . As a result, efficient purification is performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing the principle of the present invention.
FIG. 2 is a conceptual cross-sectional view of a crystallization apparatus used in a preliminary experiment.
FIG. 3 is a conceptual cross-sectional view of one embodiment of the crystallizer of the present invention.
4 is a conceptual cross-sectional view showing a modification of FIG.
FIG. 5 is a conceptual perspective view of another modification of FIG. 3;
6 is a conceptual perspective view of a modified example in which the units of FIG. 5 are arranged.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing of crystallizer 2 Refinement | purification part 3 Crystallization part 4 Processed liquid 5 Crystal 6 Exclusion liquid 7 Rotating shaft 8 Crystallization tank

Claims (6)

In a crystallization apparatus comprising a hollow housing having a purification part and a crystallization part, and having a crystal recovery part at the bottom of the hollow housing ,
The hollow housing is disposed inclined with respect to and the vertical line does not rotate, crystallizer, characterized in that it comprises a supply of the liquid to be treated between the purification unit and the crystallization unit. The crystallizer according to claim 1, wherein the hollow housing is inclined at an angle of 60 degrees at the maximum from the vertical line. Crystallizer according to means for scraping crystals adhering to the inner wall of the hollow housing to claim 1 or 2 further comprising in the interior of the hollow housing. The crystallizer as described in any one of Claims 1-3 comprised by the single hollow housing in which the refinement | purification part and the crystallization part continued. In a crystallization apparatus having a crystallization part and a purification part ,
The refining part is composed of a hollow housing, the hollow housing is not rotated and is arranged to be inclined with respect to the vertical line, has a crystal recovery part at the bottom of the hollow housing, and is provided as a separate crystallization part. crystallizer slurry, characterized in that it is supplied to the top of the refining section coming from. Crystallizer according to means for scraping crystals adhering to the inner wall of the hollow housing to Claim 5 having in the interior of the hollow housing.

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