JPH10244102A - Crystallizer and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate an agitator, to prevent increase in cooling time and to prevent deterioration of filterability of crystals by bringing a crystallizing liquid into direct contact with immiscible liquid refrigerant with it, in a crystallization method crystallizing by cooling. SOLUTION: In the case that the crystallization is performed by cooling, the liquid refrigerant 3 cooled with a cooler C1 is introduced into a crystallizing tank 1 through a pipe 6, and the crystallizing liquid 2 is introduced into the upper part from an introduction port 8. Next, the liquid refrigerant 3 immisible with the liquid 2 cooled with the cooler C1 is introduced through a pipe 7 (in some case, simultaneously from the pipe 6 too) into the tank 1. At this time, the liquid refrigerant 3 is introduced aslant along the inside wall of the crystallizing tank 1 and the crystallizing liquid 2 is cooled while it is fluidized, and during some time until crystals deposit, the liquid refrigerant 3 is repeatedly circulated. When the crystal starts to deposit, the liquid is stayed calmly for a specified time to separate the crystallizing liquid 2 from the liquid refrigerant 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystallization apparatus and a crystallization method wherein a solution to be crystallized is brought into direct contact with a liquid refrigerant immiscible with the solution.

[0002]

2. Description of the Related Art Crystallization is an operation for depositing crystals from a liquid phase or a gaseous phase, and the precipitation of crystals occurs in a supersaturated state. The supersaturated state is caused by cooling (heating when the saturation concentration is reduced by raising the temperature), evaporation, reaction, pressurization, and the like. In the present invention, the supersaturated state is a liquid phase and is intended for cooling.

[0003] There are various cases of crystallization depending on the solution state of the target substance and the demand for the obtained crystals, and it is important to select a crystallization apparatus and method according to the target.

For example, many conventional crystallization apparatuses have a cooling jacket and a stirrer, and maintain a crystal suspension state by stirring. On the other hand, there is a problem that crystal breakage occurs due to stirring. In some cases, the filterability is reduced.

[0005] Therefore, in the case of a material having poor filterability, for example, a certain kind of organic compound (for example, a coupler for a photosensitive material), the crystallization must be performed in a stationary state due to the above-mentioned problems. . Further, when cooling is performed by a jacket or the like, the crystals precipitated on the cooling surface are solidified like a block, making it difficult to discharge from the crystallizer, and using a stirrer to discharge the blocked crystals from the crystallizer. When the block is crushed, there is a problem that some crystals are crushed at that time, and the filterability is deteriorated.

[0006] Therefore, the cooling temperature cannot be reduced so much, and the cooling efficiency (transmission) by the above-mentioned block is affected, thereby increasing the cooling time.

[0007] To solve such a problem, there is a method of directly contacting a refrigerant without using a fixed heat transfer surface. However, in such a case, a device for recompressing and using a refrigerant such as propane, butane, or methane is required, which is costly, and has a problem that scale is easily generated on the nozzle surface. As such an example, see, for example,
No. 27802 describes a direct contact crystallization apparatus that uses a draft tube in combination with a gas or liquid injection nozzle to cool and agitate the crystal slurry. And circulate through the draft tube.

In such a case, since there is no fixed heat transfer surface,
As the refrigerant, nitrogen, helium, and other vaporized liquids are used, and the above-mentioned problems of cost, scale, and the like still remain. In addition, the vaporized liquid causes a violent fluid state due to rapid volume expansion when vaporized, and there is a risk that crystal breakage due to particle collision may occur particularly in a soft organic compound crystal. Further, the supersaturation of the part of the solution in contact with the vaporized liquid at a very low temperature rapidly increases, and very fine natural nuclei are generated, which may deteriorate the filterability.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to prevent an increase in cooling time without using a stirrer in a solution to be crystallized, and to further improve the operability of discharging crystals. It is an object of the present invention to provide a crystallization apparatus and a crystallization method which are excellent in crystallinity and can prevent deterioration of filterability of obtained crystals.

[0010]

The above object of the present invention is achieved by the following means.

[0011] A crystallization method in which crystallization is performed by cooling, wherein a solution to be crystallized is brought into direct contact with a liquid refrigerant immiscible with the solution.

The crystallization method according to the above item, wherein the liquid refrigerant is circulated.

[0013] A crystallizer for performing crystallization by cooling, wherein a solution to be crystallized is brought into direct contact with a liquid refrigerant immiscible with the solution.

[0014] The crystallization apparatus according to the above item, wherein the liquid refrigerant is circulated.

[0015] The crystallization apparatus according to the above or the item, further comprising a stirrer in the liquid refrigerant.

Hereinafter, the present invention will be described specifically.

The crystallization method of the present invention is applied to crystallization when it is not preferable to use a stirrer. In the present invention, since the liquid refrigerant and the liquid to be crystallized come into direct contact with each other and do not use a liquefied gas as in the so-called direct method, the apparatus costs and running costs are not required, and the operability and the discharge property of the crystal slurry are good. It is.

The liquid refrigerant in the present invention is not particularly limited as long as it is immiscible with the solution to be crystallized and does not dissolve the solution to be crystallized. Examples of such a combination include methanol / toluene and methanol / hexane, but it is necessary that the solute to be crystallized is not dissolved.

As an example in which water is used as such a liquid refrigerant, for example, the compound is crystallized from a solution of a certain organic compound (for example, a coupler used in photographic light-sensitive materials) dissolved in an organic solvent. There are cases.

In the present invention, the liquid refrigerant is preferably flowing. As the liquid refrigerant flows,
The crystallization solution in contact therewith also flows, and the precipitated crystals become a crystal slurry having fluidity. In other words, the use of a stirrer for the solution to be crystallized may cause the above-described problem because the breaking force of the blade is strong.
There is almost no problem when the crystallized liquid flows due to the flow of the contacting refrigerant.

The flow of the liquid refrigerant depends on the state of the target crystal slurry, for example, its physical properties (viscosity,
Specific gravity, etc.) and the liquid refrigerant combined therewith, but as a method of improving the flow, it is preferable to circulate the liquid refrigerant and increase the flow rate and circulation speed at the time of introduction,
In addition, the introduction of the liquid refrigerant is performed diagonally along the wall,
Alternatively, there is a method in which a solvent is mixed into the solution to be crystallized, the separated solvent is suctioned and mixed again, and the liquid refrigerant is positively stirred, and only the liquid refrigerant is stirred. . A liquid refrigerant is introduced into the solution to be crystallized, temporarily mixed, cooled, and then allowed to stand. The solution to be crystallized and the refrigerant are naturally separated by a difference in specific gravity, and the solution to be crystallized is discharged.

By flowing the liquid solvent in this manner, a stirring effect is given to the solution to be crystallized in contact with the liquid solvent, and the crystal slurry can be suspended to cause good crystal growth.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The crystallization apparatus and the crystallization method of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the crystallization apparatus of the present invention. FIG. 1 shows the case where the specific gravity of the liquid refrigerant is larger than the solution to be crystallized, and FIG. Is small.

In FIG. 1, reference numeral 1 denotes a crystallization tank provided with a cooling jacket 4a or 4b. 2 is a liquid to be crystallized, and 3 is a liquid refrigerant. The crystallization method can be performed in the following cases.

The liquid refrigerant 3 cooled by the cooler C ₁ is introduced into the crystallization tank 1 through a pipe 6, and a liquid to be crystallized on the upper part is introduced through an inlet 8. However, when the specific gravity of the liquid refrigerant is larger than the liquid to be crystallized.

First, the liquid 2 to be crystallized is introduced into the crystallization tank 1, and the liquid refrigerant 3 cooled by the cooler C ₁ is introduced into the crystallization tank 1 from the pipe 7 (in some cases, simultaneously introduced from the pipe 6). be introduced. At this time, it is preferable that the liquid refrigerant is introduced obliquely along the inner wall of the crystallization tank, so that the liquid to be crystallized is cooled while flowing. It is effective to repeatedly circulate the liquid refrigerant for this operation until the crystals are deposited.

After that, when the crystal starts to precipitate, the liquid to be crystallized is separated from the liquid refrigerant by standing still for a certain period of time. At this time, the upper and lower parts to be separated are reversed due to the specific gravity difference between the liquid 2 and the liquid refrigerant 3 to be crystallized. That is, FIG.
FIG. 2 shows a case where the specific gravity of the liquid 2 to be crystallized is large.

In the initial stage of crystal precipitation, the mixture is allowed to stand for an appropriate time, and after the two layers are separated, a stirrer 9 having a stirring blade 10
May be used to stir the liquid refrigerant 3. As a result, the liquid refrigerant 3 is effectively cooled by the cooling jacket 4a or 4b in contact with the liquid refrigerant, and at the same time, the liquid refrigerant 3 flows, thereby giving a flow also to the crystallizing liquid 2 in contact with the liquid refrigerant 3 to cool and crystallize. Good results can be obtained.

As a result of applying the above-described apparatus and method to the crystallization of a coupler for a photographic light-sensitive material, a satisfactory crystal slurry can be obtained without any problem in discharging the crystal slurry. And could be filtered.

[0031]

Industrial Applicability According to the present invention, a crystal capable of preventing an increase in cooling time without using a stirrer in a solution to be crystallized, having excellent operability of discharging the crystal, and preventing deterioration of filterability of the obtained crystal. The present invention has provided a crystallizer and a crystallization method.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a crystallization apparatus of the present invention.

FIG. 2 is a sectional view showing an example of the crystallization apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystallization tank 2 Liquid to crystallize 3 Liquid refrigerant 4a, 4b Cooling jacket 5 Three-way valve 6,7 Introduction pipe 8 Liquid introduction port to crystallize 9 Stirrer 10 Stirrer blade

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 9/02 611 B01D 9/02 611C

Claims (5)

[Claims] 1. A crystallization method in which crystallization is carried out by cooling, wherein a solution to be crystallized is brought into direct contact with a liquid refrigerant immiscible with the solution. 2. The crystallization method according to claim 1, wherein the liquid refrigerant circulates. 3. A crystallization apparatus for performing crystallization by cooling, wherein a solution to be crystallized is brought into direct contact with a liquid refrigerant immiscible with the crystallization solution. 4. The crystallization apparatus according to claim 3, wherein said liquid refrigerant circulates. 5. The crystallization apparatus according to claim 3, wherein a stirrer is provided in the liquid refrigerant.