JP5695831B2 - Crystallizer - Google Patents

Description

  The present invention relates to a crystallizer. More specifically, the present invention relates to a crystallization apparatus having an internal circulation type microcrystal dissolution function. The crystallization apparatus of the present invention is particularly effective in the case of cooling crystallization and poor solvent crystallization.

  As a crystallization method, a method of crystallization by evaporating a solvent and increasing a concentration of a solute is known. In addition, there are a crystallization method in which a crystal is grown by cooling the solution and lowering the solubility, a crystallization method in which the crystal is grown by mixing the solution and a poor solvent to lower the solubility, and a crystallization method combining these. It is common. In the crystallization process that places importance on filterability, large crystals with a small particle size and a uniform particle size are usually desired.

  However, in the method of crystallizing by evaporating the solvent, the concentration of the substance to be crystallized increases in the solution, and when stirring and mixing is not sufficient, the rate of evaporation of the solvent decreases, so the crystallization proceeds only gradually. First, there is a problem that the particle size distribution of the obtained crystal particles becomes broad. Further, there is a cost problem that the solvent must be evaporated for a long time. In the case of cooling crystallization and poor solvent crystallization, fine crystals may be generated with cooling or mixing with a poor solvent, which may make filtration difficult.

  In order to solve such a problem, in Patent Document 1, when cooling crystallization or poor solvent crystallization is performed, a heating unit is provided on the wall of the stirring tank, and a liquid ejection device is used to include microcrystals. A crystallization apparatus is disclosed in which a liquid, slurry, or the like is sprayed on the inner wall of a stirring tank to dissolve microcrystals.

  However, since the crystallizer described in Patent Document 1 spreads the slurry on the inner wall of the stirring tank, for example, a low-viscosity liquid, slurry or the like immediately flows down from the inner wall of the stirring tank and sufficiently dissolves the microcrystals. There are cases where it is not possible. Further, since the liquid containing the crystal is sprayed on the inner wall, the scattered crystal may remain attached to the inner wall surface. Furthermore, it is necessary to install a heating jacket or the like on the outer wall of the stirring tank in order to dissolve minute crystals, which is difficult to install with an existing crystallizer.

International Publication No. 2001/14037

  An object of the present invention is to provide a crystallizer capable of dissolving microcrystals without spraying liquid, slurry or the like containing microcrystals on the inner wall of a stirring tank, and obtaining large crystals with uniform particle diameters. It is in.

  The present invention is a crystallization apparatus comprising a stirring tank, a stirring shaft, a crystal dissolving means, and a heating means for heating the crystal dissolving means, the crystal dissolving means being arranged around the stirring shaft. The contents in the agitation tank are introduced into the crystal dissolution means as the crystal dissolution means rotates, and the fine crystals in the contents are dissolved. A crystallizer is provided.

  In one embodiment, the crystal dissolving means is composed of a hollow truncated cone shape; or a hollow truncated cone portion and a cylindrical portion, and an end portion of the truncated cone portion having a large outer diameter and an end of the cylindrical portion. And the contents in the agitation tank are introduced into the crystal dissolving means from the end portion of the truncated cone portion having a small outer diameter.

  In one embodiment, the heating means is provided on the outer wall surface or the inner wall surface of the crystal melting means.

  In another embodiment, the heating means is a cable heater, electromagnetic induction heating, steam or a heating medium.

  According to the present invention, there is provided a crystallizer capable of dissolving microcrystals without spraying a liquid, slurry, or the like containing microcrystals on the inner wall of a stirring tank, and obtaining large crystals with uniform particle diameters. Can do.

It is the schematic which shows one embodiment of the crystallizer of this invention. In the crystallization apparatus of the present invention, one embodiment is shown in which a stirring tank is provided with a stirring shaft, a crystal dissolution means, and a crystal dissolution means fixed shaft, (a) shows a top sectional view, (b) shows ( a) AA ′ longitudinal sectional view, and (c) a BB ′ longitudinal sectional view of (a). It is a graph which shows the cumulative weight distribution of the glycine crystal obtained using the crystallizer of this invention.

  The crystallization apparatus of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing an embodiment of the crystallization apparatus of the present invention. The crystallization apparatus 1 of FIG. 1 includes a stirring tank 2, a stirring shaft 3, a crystal dissolving means 4, and a heating means (hereinafter sometimes simply referred to as a heating means) 6 for heating the crystal dissolving means. The crystallization apparatus of the present invention further includes an apparatus for mixing a solution and a poor solvent when used for poor solvent crystallization.

  The stirring tank 2 is not particularly limited in terms of material and shape as long as it can be used for stirring liquid, slurry and the like. The size (capacity) of the stirring tank 2 can be appropriately set depending on the substance to be crystallized, the amount, and the like.

  The stirring tank 2 is preferably provided with a cooling means on its outer wall surface. Examples of the cooling means include a water cooling type cooling means as shown in FIG.

  The agitation shaft 3 is usually provided with at least one agitation blade and configured to agitate the contents in the agitation tank 2. The stirring blade is not particularly limited as long as it has a size and shape that can stir the contents in the stirring tank 2. The stirring shaft 3 preferably has a biaxial structure so that the stirring blade and the crystal dissolution means 4 can be driven independently.

  One end of the stirring shaft 3 is connected to a rotating means such as a motor in the upper part of the stirring tank 2. The other end of the stirring shaft 3 is not connected to the bottom of the stirring tank 2, but is positioned near the bottom of the stirring tank 2. The stirring blade is preferably provided near the other end of the stirring shaft 3.

  The length and outer diameter of the stirring shaft 3 are not particularly limited, and can be appropriately set depending on the size and shape of the stirring tank 2.

  The crystal dissolving means 4 dissolves microcrystals contained in the contents in the stirring tank 2. In the present specification, “microcrystal” refers to a small particle size fraction of crystals generated with a distribution in particle size, and the particle size depends on the characteristics of the substance to be crystallized.

  The crystal dissolving means 4 is provided inside the stirring tank 2 so as to rotate around the stirring shaft 3. For example, as shown in FIG. 1, the crystal dissolving means 4 is fixed to a crystal dissolving means fixing shaft 5 provided so as to cover the stirring shaft 3, and the stirring shaft 3 and the crystal dissolving means fixed shaft 5 are independent. And is configured to rotate.

  The size of the crystal dissolution means 4 is not particularly limited as long as it is a size that can enter the inside of the stirring tank 2, and can be appropriately set depending on the size of the stirring tank 2.

  The crystal dissolution means 4 is preferably made of metal (for example, aluminum, stainless steel, Hastelloy, etc.) in order to dissolve the microcrystals by heating. From the viewpoint of chemical resistance, it is more preferably made of stainless steel.

  The crystal dissolution means 4 rotates by rotating the crystal dissolution means fixed shaft 5 and pumps up the contents in the agitation tank 2 using the rotational force. The contents in the agitation tank 2 pumped up by the crystal dissolving means 4 and introduced into the crystal dissolving means 4 are heated to dissolve the microcrystals contained in the contents.

  The crystal dissolution means 4 is not particularly limited as long as the content in the stirring tank 2 is introduced and stays in the crystal dissolution means 4 and the fine crystals in the content are dissolved. For example, by providing a stirring blade inside the crystal dissolving means 4 or processing the inner wall of the crystal dissolving means 4 in a spiral shape, when the crystal dissolving means 4 rotates, a pumping force is obtained, and the inside of the stirring tank 2 The contents are pumped up to the crystal dissolution means 4.

  In order to introduce and retain the contents in the stirring tank 2 in the crystal dissolution means 4, the rotation speed of the crystal dissolution means 4 (that is, the rotation speed of the crystal dissolution means fixed shaft 5) is the viscosity of the contents, the stirring tank. It depends on the size of 2. That is, since centrifugal force is used to introduce the contents in the stirring tank 2 into the crystal dissolution means 4, it is necessary to increase the rotational speed when the stirring tank 2 is small, and when the stirring tank 2 is large. The rotational speed may be slowed down. The rotation speed is usually preferably 50 rpm to 500 rpm, more preferably 60 rpm to 400 rpm.

  For example, as shown in FIG. 1, the crystal dissolution means 4 includes a truncated cone part 41 and a cylindrical part 42 having a hollow structure, and an end part having a large outer diameter of the truncated cone part 41 and one end of the cylindrical part 42 are formed. A connected shape is preferred. With such a shape, the contents in the stirring tank 2 are introduced into the crystal dissolution means 4 from the end of the truncated cone part 41 having a small outer diameter. The content introduced into the crystal dissolving means 4 stays and the microcrystals can be easily dissolved. The content in which the microcrystals are dissolved returns to the stirring tank 2 from the upper part of the cylindrical part 42 (that is, the end opposite to the connection part with the truncated cone part 41). Further, depending on the size of the stirring tank 2 and the viscosity of the contents, the crystal dissolving means 4 may have a shape of only the truncated cone part 41 (conical trapezoidal shape).

  The heating means 6 is used for heating the crystal melting means 4. The heating means 6 is not particularly limited. For example, a cable heater provided on the outer wall surface of the crystal melting means 4, steam (such as water vapor) from the rotating shaft 3 (or the crystal melting means fixed shaft 5), a heat medium (heat medium oil) , Warm water, etc.) to the crystal dissolution means 4 (see FIG. 2), means for heating the crystal dissolution means 4 by electromagnetic induction from the outside of the stirring tank 2, and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these Examples.

Example 1
Using a crystallizer as shown in FIG. 1, glycine was crystallized.

  A stirring shaft was attached to a stirring tank having a capacity of 3.0 L, and one end of the stirring shaft was fixed to the motor. 1.7 L of a solution in which glycine was dissolved at a rate of 250 mg / mL at 70 ° C. was put into a stirring tank. Next, a crystal melting means composed of a hollow aluminum truncated cone part and an aluminum cylindrical part, in which the end part having a large outer diameter of the truncated cone part and one end of the cylindrical part are connected, It fixed to the crystal-dissolving means fixed shaft so that the edge part with a small outer diameter of a base part might be immersed in a glycine solution. A cable heater was wound around the outer wall surface of the crystal melting means.

  Next, after the glycine solution was cooled to 40 ° C., it was cooled to 25 ° C., which became supersaturated, at a rate of 10 ° C. per hour. The crystal dissolution means was heated by controlling the output of the cable heater to 150 W while cooling the glycine solution while rotating the stirring shaft at 400 rpm and the rotation speed of the crystal dissolution means fixing shaft at 400 rpm.

  For 30 minutes after the temperature of the solution in the stirring tank reached 25 ° C., both the stirring shaft and the crystal dissolution means fixing shaft were continuously rotated. Thereafter, heating of the crystal dissolution means and rotation of the crystal dissolution means fixed shaft were stopped, only the stirring shaft was rotated, and the glycine solution was further stirred for 1 hour. The reason why the solution is stirred for 1 hour after stopping the heating of the crystal dissolving means is to allow the glycine dissolved by heating to grow again. In addition, it is not necessary to continue this stirring, when a crystal | crystallization is crushed and a microcrystal increases by continuing stirring after stopping the heating of a crystal dissolution means.

  The obtained crystals of glycine were subjected to suction filtration, and after drying the crystals, the particle size and particle size distribution of the crystals were measured by sieving. The results are shown in FIG. Note that 0 W in FIG. 3 indicates the result (control experiment) in which the crystal dissolution means was not heated and rotated.

(Example 2)
A glycine crystal was obtained in the same procedure as in Example 1 except that the output of the cable heater was 210 W, and the crystal grain size and particle size distribution were measured. The results are shown in FIG.

(Example 3)
Except that the output of the cable heater was 270 W, glycine crystals were obtained in the same procedure as in Example 1, and the crystal grain size and particle size distribution were measured. The results are shown in FIG.

  As shown in FIG. 3, it can be seen that the ratio of microcrystals decreases and the ratio of large crystals increases when the output of the cable heater is 150 W, 210 W, or 270 W. In particular, it can be seen that there are fewer microcrystals at 210 W than at 150 W. This is presumably because the temperature of the crystal dissolution means was higher at 210 W, and the microcrystals were sufficiently dissolved. In addition, it is assumed that there is almost no difference in particle size distribution between 210 W and 270 W because the crystallites are sufficiently dissolved in either case. The amount of crystals obtained was almost the same in any of Examples 1 to 3.

  According to the present invention, there is provided a crystallizer capable of dissolving microcrystals without spraying a liquid, slurry, or the like containing microcrystals on the inner wall of a stirring tank, and obtaining large crystals with uniform particle diameters. Can do.

DESCRIPTION OF SYMBOLS 1 Crystallizer 2 Stirrer tank 3 Stirring shaft 4 Crystal dissolution means 41 Frustum part of hollow structure 42 Cylindrical part 5 Crystal dissolution means fixed shaft 6 Heating means

Claims (4)

A crystallization apparatus comprising a stirring tank, a stirring shaft, a crystal dissolving means, and a heating means for heating the crystal dissolving means,
The crystal dissolving means is provided to rotate independently around the stirring shaft inside the stirring tank;
A crystallizer configured so that the contents in the stirring tank are introduced into the crystal dissolving means and stays with the rotation of the crystal dissolving means, and the fine crystals in the contents are dissolved. .   The crystal dissolving means is formed of a hollow truncated cone shape; or a hollow truncated cone portion and a cylindrical portion, and a shape in which an end portion of the truncated cone portion having a large outer diameter is connected to one end of the cylindrical portion. The crystallization apparatus according to claim 1, wherein the content in the stirring tank is introduced into the crystal dissolving means from an end portion of the truncated cone portion having a small outer diameter.   The crystallization apparatus according to claim 1 or 2, wherein the heating means is provided on an outer wall surface or an inner wall surface of the crystal melting means.   The crystallization apparatus according to any one of claims 1 to 3, wherein the heating means is a cable heater, electromagnetic induction heating, steam, or a heating medium.

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