JPS6218201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystallization method and a crystallization apparatus for growing crystal grains as large as possible using pressure as a parameter.

[Conventional technology]

In the conventional crystallization method using temperature as a parameter, a mixture containing two or more components is used as a starting material, and by cooling it, a specific component is solidified, and then solid-liquid is separated. Often, a large amount of fine crystals flow out, and the remaining solid phase contains fine particles, which hinders sufficient solid-liquid separation.

[Problems to be solved by the invention] Therefore, a method has been proposed in which a circulation method is adopted to obtain high-quality crystals. That is, the process of separating the mother liquor from the solid-liquid coexistence system, heating up the fine crystals contained therein, melting them, and returning them to the coexistence system is repeated, thereby suppressing the generation of new nuclei and suppressing the growth of existing crystal grains. This is a method of sequentially prompting (hereinafter referred to as providing temperature history). The heating and melting temperature here refers to the temperature at which not only the fine crystals in the mother liquor melt, but also until the molecular structure of the molten liquid phase becomes completely disordered, that is, a state called a cluster (despite being in the liquid phase, Note that it is necessary to raise the temperature to a state where the remaining molecular groups as crystals are dissolved. Therefore, it is sometimes necessary to raise the temperature by more than 10°C above the melting temperature, and it is necessary to repeatedly and continuously perform cooling operations to return it to a solid-liquid coexistence system and grow crystals, which consumes a large amount of energy. There are production problems associated with this.

The present inventors have long proposed and researched a crystallization method using high pressure as a parameter, but in general, viscosity increases under pressure reaching several thousand atmospheres, and solidification progresses rapidly under such high pressure. In this case, the proportion of fine crystals often increases, causing a decrease in solid-liquid separation. Further, as mentioned above, fine particles may be mixed into the separated liquid phase, reducing the yield. It is difficult to give the mother liquor separated by such high-pressure crystallization the temperature history under pressure. That is, high-pressure vessels and piping have very thick structures, and if a device for heating or cooling them from the outside is used, thermal efficiency will be impaired. Putting a heat exchanger inside would make the high-pressure container itself very large and the mechanism would be difficult.

The present invention has been made in view of these circumstances, and its purpose is to not only recover the fine crystals that flow out together with the mother liquor in a crystallization method that uses pressure as a parameter, but also to recover as many crystal grains as possible. The purpose is to provide a method and apparatus for growing large plants.

[Means for solving problems]

The basic structure of the present invention that achieves the above object is as follows.

First, a mixture in which a specific component is supersaturated under high pressure is made into a fluid state, and after generation and/or supply of crystal nuclei consisting of the specific component, crystals of the specific component are grown and increased in a high-pressure container to solidify. A liquid coexistence product is obtained, and the mother liquor separated from this system together with fine crystals is depressurized to melt the crystals, and the pressure is further reduced to eliminate the clusters, and then the pressure is applied again to obtain supersaturation in which no crystals are precipitated. The gist lies in that the crystal grains are injected again into the high-pressure vessel in which the crystals remain in this state and brought into contact with the crystals in the high-pressure vessel to promote the growth of the crystal grains. The mother liquor, which has been once depressurized and repressurized, may be cooled as necessary to prevent temperature rise in the circulation system, and then injected into the high-pressure container in a state in which specific components are supersaturated.

In addition, a device having the following configuration is provided as a suitable device for carrying out these operations. That is, a pressurization and pressure adjustment device for a raw material mixture, a high-pressure container that stores the raw material under pressure, a mother liquid separation pipe and an outflow that separates mainly the mother liquor in a solid-liquid coexistence state in the high-pressure container while keeping it in a pressurized state. A basic device including a mother liquor pressure regulating device and a mother liquor return pipe, as well as a seed crystal generation or supply device, and variations thereof are provided.
With this device the basic pressure history operation described above can be carried out conveniently.

[Function and Examples]

The configuration and effects of these inventions will be explained below. However, the following example explanations are not intended to limit the present invention like the embodiments described in the claims, and are not intended to limit the present invention. It is within the technical scope of the present invention to carry out modifications according to the purpose.

Now, a mixture containing two or more components is made to coexist with solid and liquid under pressure, including the case where a specific component contains a slight impurity. The raw material in this case may be in a liquid phase under atmospheric pressure or in the form of a slurry containing a solid phase, but the amount of solid phase generally increases by pressurization. Furthermore, by cooling after pressurization, a solid phase can be generated at a much higher temperature than under atmospheric pressure, or an increase in the amount of solid phase can be promoted. The crystal grain size of the solid-liquid coexistence state obtained under pressure is as non-uniform as under atmospheric pressure.
The distribution shown in the figure is shown. Assuming that the crystals smaller than the grain size Df are incompatible, we first select a from the distribution 1 obtained in the first crystallization.
An amount of microcrystals corresponding to the area within the loop surrounded by Df·a′ is separated from other large-diameter crystals and melted. In reality, when the mother liquor is separated, it often flows out of the filter together with the mother liquor. When this is pressurized as it is or mixed with a liquid phase raw material mixture to form a supersaturated solution, it is poured into a high-pressure container containing crystals (or further pressurized), and the remaining crystals in the container are used as seed crystals to form crystal grains. growth occurs, and a solid phase of distribution 2, which has many larger particles than distribution 1, is obtained. So, for the same reason as last time, b.
An amount of microcrystals corresponding to the area within the loop surrounded by Df·b′ is separated and melted. When this is further processed according to the same procedure as above, a crystal exhibiting a new distribution 3 is obtained. In this way, loop c.
If the small grain size crystals of Df・c′, loop d・Df・d′ are successively separated and melted and crystallization continues, distribution 5 will eventually be reached, and a solid phase consisting of crystal groups larger than desired will be formed. can get.

The above is the basic principle of the method of the present invention. Generally, when separating solids and liquids coexisting in a high-pressure container, a filter is used, and crystals larger than the mesh of the filter are captured by the filter. Crystals smaller than the mesh are allowed to pass along with the mother liquor. Therefore, when a filter consisting of a predetermined mesh mesh is attached to a high-pressure container and solidification is proceeded by or under pressure, for example, a solid phase consisting of a crystal group of distribution 1 and a mother liquor coexisting therewith are obtained. When this solid phase is filtered and the mother liquor is discharged from the filter, crystals smaller in particle size than the mesh are also discharged together with the mother liquor. Therefore, assuming that all of the small grain size crystals pass through the filter without being trapped in the solid phase, it is possible to separate and remove the small grain size crystals that are smaller than Df. However, the crystal distribution at that time remains 1, and it is not possible to obtain a distribution like 5 explained earlier, and the crystal grain size is generally small and corresponds to the loop a, Df, a' portion. Since certain components must be discarded, the yield will naturally be low. Moreover, as a practical matter, there are small-sized crystals that are trapped in the solid phase, and it is not possible to obtain a suitable crystal distribution simply by draining the liquid.

The present invention takes this point into consideration, and attempts to provide a distribution as close to 5 as possible by returning the small-sized crystals separated by the filter to the high-pressure vessel together with the mother liquor and bringing them into contact with the crystals in the vessel. We are trying to measure the sequential growth of crystals. However, if the small-sized crystals that passed through the filter were returned to the high-pressure container,
The small particle size crystals and mother liquor are simply sent back and forth as they are through a filter, and although some specific components in the mother liquor may precipitate, the distribution is essentially 1.
It cannot be something that escapes. Therefore, we found that it is necessary to melt the small-sized crystals and then return them to the high-pressure vessel, and measure their growth using the crystals in the high-pressure vessel as nuclei. However, there are two methods for melting these small-sized crystals: a method of heating and increasing the temperature while maintaining the pressure at which it exits the filter as described above, and a method of reducing the pressure. The former method is not preferable because the heated molten raw material is again injected into the high-pressure container, which increases the temperature inside the container and impairs the progress of solidification. Therefore, it becomes necessary to cool it again. I have already mentioned the problems at that time. In comparison, the latter method is based on the basic idea of the present invention that pressure is used as a parameter, and it is possible to adopt a repeated pattern of reducing pressure with a pressure regulator and then increasing pressure with the same or another pressure regulator. Therefore, for example, carrying out the procedure of sequentially shifting the distribution from (1) to (5) as shown in Figure 1 is extremely difficult in terms of energy, equipment, and time. It's advantageous. Therefore, in the present invention, the small-sized crystals taken out together with the liquid phase from the solid-liquid coexistence system are melted by lowering the pressure.

By the way, the degree of this pressure drop should naturally be determined by the composition of the solid-liquid mixture that has flowed out of the high-pressure vessel, and when the solid-liquid mixture is returned into the high-pressure vessel, the small-sized crystals have completely melted. It is also necessary that the clusters described below have disappeared. Since the solid-liquid equilibrium pressure changes depending on the composition of the mixture, the theoretical pressure drop required to melt the solid phase in the mixture is (pressure when flowing out of the high-pressure vessel) - ( The pressure drop must be greater than that given by the solid-liquid equilibrium pressure of the effluent mixture composition. When the pressure is lowered to below the solid-liquid equilibrium pressure of the mixture composition, not only the small size crystals but also the clusters in the mixture completely disappear. A cluster here refers to a cluster that is usually an aggregate of several dozen molecules, and even when a crystal melts and becomes a liquid, the molecules are not arranged in a completely disordered state. is known to solidify again. Therefore, a large degree of supersaturation cannot be achieved, nucleation easily occurs upon cooling, and the presence of many clusters results in the generation of many fine particles. The research conducted by the present inventors has revealed that even when the pressure is reduced, this cluster exists even at pressures considerably lower than the solid-liquid equilibrium pressure. The basic idea of the present invention is to reduce the pressure to the disappearance pressure of the clusters, which is lower than the solid-liquid equilibrium pressure, but since the clusters are eliminated by molecular diffusion, the clusters must be vigorously stirred after the pressure is reduced to eliminate the clusters. You can also do it.

The completely melted effluent mixture is pressurized as it is or mixed with a new raw material mixture, and is injected into the high-pressure vessel in a supersaturated state to contact the crystals remaining in the vessel. However, since the inside of the container is maintained under a pressure higher than the solid-liquid equilibrium pressure of the newly injected mixture, certain components in the liquid phase mixture that have come into contact with the crystals in a supersaturated state can be used as seed crystals. It crystallizes and grows as crystals with larger grain size. The portion where the specific component independently crystallizes and grows sequentially is extremely small, resulting in a distribution such as 2 shown in FIG. 1, for example. However, if the ratio of crystal formation using large grain crystals as seed crystals is increased, the grain size in distribution 2
The distribution to the left of Df can also have a smaller area. This method is achieved by adjusting conditions such as matching the composition and internal pressure so that the degree of supersaturation of the reinjected mixture, such as the mother liquor, which has been once depressurized, does not become extremely high. It is clear from the nature of the cluster that such an operation can be accomplished only when the cluster has completely disappeared. It is clear that the amount of pressure reduction required to completely eliminate such clusters varies depending on the components and composition of the mixture, but it should be 50 kg/cm 2 or more, more preferably 100 kg/cm ² or more than the solid-liquid equilibrium pressure of the composition.
We learned that it is desirable to lower the pressure to a level lower than Kg/cm ² . Furthermore, 300Kg/cm ² or more may be required to be sure. By the way, high-purity benzene has solid-liquid equilibrium at about 700 kg/cm ² at 250°C. After lowering the pressure from this equilibrium pressure and confirming that the crystals were completely melted, the pressure was further reduced and then pressurized again. In this case, when the equilibrium pressure was lowered by 20 kg/cm ² , supersaturation was already eliminated when the repressurization pressure was raised to 50 kg/cm ² higher than the equilibrium pressure. Furthermore, the supersaturation pressure reached 400 Kg/cm ² when the pressure reduction amount was 70 Kg/cm ² . If the pressure is lowered to this point, no clusters will remain; therefore, the mixture that is re-pressurized and reinjected into the high-pressure container is a completely supersaturated liquid phase, and the generation of new crystal nuclei within the container is suppressed. , crystal growth can be promoted using the remaining crystals as seed crystals.

Incidentally, such promotion of crystal growth is carried out by bringing the crystals into contact with the supersaturated mother liquor in a high-pressure container, and this supersaturated state can be obtained by cooling as necessary by applying pressure. Further, the pressure of the mixture containing residual crystals in the high-pressure container may be adjusted in advance, and in short, it can be adjusted as desired to obtain appropriate supersaturation and solidification rate. Further, solidification may be promoted by gradually cooling the solid-liquid coexistence system in the high-pressure container under pressure or by removing latent heat of solidification. Note that when one cycle consists of outflowing, melting, and re-injecting small grain size crystals, the present invention achieves its purpose to some extent even with just one cycle; however,
Of course, the process can be repeated several cycles. Naturally, this process can also be carried out in continuous circulation.

Furthermore, in the above explanation, it was stated that the small-sized crystals are melted after flowing out, but since it is possible to partially melt them even in a high-pressure container, a brief explanation will be added below. FIG. 2 is an enlarged schematic diagram showing the solid phase inside the high-pressure vessel, in which there are small crystals S _B and a liquid phase L between the large crystals S _A. When these are near the filter, both the liquid phase L and small-sized crystals S _B are released to the back side of the filter due to filtration, but when these are located away from the filter, they are sufficiently released. Rather, it should be considered that the small grain size crystals S _B remain as they are together with the liquid phase. Therefore, even if the above-mentioned cycle is repeated, the small-sized crystals S _B that have been incorporated in this manner often remain as they are, and there is a fear that the degree of crystal growth may become unbalanced. . Of course, the structure shown in FIG. 2 will be decomposed and dispersed to some extent due to the infiltration of the reinjected liquid phase mixture, but it is thought that a similar situation will eventually occur somewhere within the high-pressure vessel.

Therefore, the present inventors propose a method of slightly lowering the pressure inside the high-pressure container in the state shown in FIG. In other words, when the pressure decreases, part of the crystal melts in order to maintain the solid-liquid equilibrium under that pressure, but it is well known from thermodynamics that the higher the impurity concentration in the liquid phase, the higher the solid-liquid equilibrium pressure. Therefore, the above partial melting can be explained as follows.
That is, when the pressure is reduced from the pressure P ₁ to the pressure P ₂ , the pressure P ₂ of the mixture system having the liquid phase L containing concentrated impurities becomes lower than the solid-liquid equilibrium pressure corresponding to the liquid phase concentration. , crystals S _A and S _B are melted, but this melting reduces the impurity concentration in the liquid phase,
Along with this, the solid-liquid equilibrium pressure also decreases, and finally the pressure P ₂
and the solid-liquid equilibrium pressure become equal. In this state, the crystal melting stops, but part of the small grain size crystal S _B melts and disappears during this time, and the large grain size crystal S _A melts the impurity-containing layer that was attached to and included in the surface layer. The particles are highly purified and some of them are reduced in particle size, and as shown in FIG. 3, the fine particles are melted and lost to form a mixture of higher purity large particle size crystals _S'A and liquid phase L'. Further, the distance between the crystal grains becomes large, and a discharge path for the liquid phase L' is secured, so that the liquid phase with a high impurity concentration can be discharged extremely easily, and there is an advantage that the purification effect itself becomes high. The liquid phase that is discharged naturally contains specific melted components, as well as small-sized crystals and clusters, so the pressure must be reduced outside the high-pressure vessel to melt the entire amount, and then the liquid phase must be melted inside the high-pressure vessel. It goes without saying that the method that should be returned to is the same as the other methods mentioned above. Moreover, the internal pressure can be increased again to further enlarge the large grain size crystals, thereby suppressing reinjection of the depressurized mother liquor, etc.

The outline of the method of the present invention has been explained above, but when handling substances that are difficult to initially crystallize in a high-pressure container, it is necessary to facilitate the generation of seed crystals or to actively supply seed crystals. This is desirable. In other words, in these substances, it is often difficult to observe the precipitation of primary crystals even in supersaturated conditions that are several hundred to several thousand atmospheres higher than the solid-liquid equilibrium pressure, and it is thought that it is necessary to take special measures as described above. . A basic method for this purpose is to apply mechanical stimulation to a supersaturated liquid phase mixture under high pressure, but it is extremely difficult to stir this mixture in a high pressure container. A specific method was to create a fluid state. And in this case,
Although the temperature of the mixture is not limited, it is natural that the temperature of the mixture is preferably supercooled. Under such conditions, even certain substances that are difficult to form primary crystals can be crystallized to some extent. In a fluidized state, for example, primary crystals flowing through a transport pipe are dispersed within the liquid phase and are constantly in contact with the supersaturated mother liquor, growing sequentially as they enter the high-pressure vessel, where the same treatment is performed thereafter. If crystal nuclei are still not generated even with these methods, a later-described nucleator, such as a seed crystal holder, a cooling body, or a turbulent flow generator, may be installed in the fluid system.

Although the basics of the present invention are configured as described above,
The various aspects will be further outlined. First, as described above, various routes can be taken to obtain a solid-liquid coexistence state under pressure. The liquid or slurry may be pressurized under atmospheric pressure to increase the generation of solid phase, or the pressurization may accelerate the increase in solid phase generation due to cooling. In the present invention, it is essential to form or supply seed crystals as detailed above. Second, the pressure at which the mother liquor in the high-pressure container is separated from the coexisting system does not necessarily need to be constant, and may be arbitrarily changed or fluctuated. Detailed description has been given of the reduced pressure for flushing out small particle sizes. Thirdly, the amount of pressure reduction to reduce the pressure of the separated mother liquor, melt the fine crystals contained therein, and further eliminate clusters varies depending on the substance and composition, but a large amount of pressure reduction is not harmful and is rather preferable. In particular, the pressure is rapidly reduced adiabatically,
When pressurizing again, a large vacuum is preferable. Therefore, one effective method is to once bring the pressure to atmospheric pressure and then repressurize it. On the other hand, in order to provide a reduced pressure of, for example, 300 Kg/cm ² , solid phase growth, mother liquor separation, etc. should be performed at a higher pressure. Fourth, the temperature and pressure inside the high-pressure vessel upon injection after repressurization do not need to be the same as those at the time of mother liquor separation. Conditions in which the interior is gradually cooled or pressurized to obtain a larger amount of solid phase and which do not result in excessive supersaturation can be arbitrarily selected. Although the mixture to be re-pressurized and injected should not contain fine seed crystals, it is more preferable to adjust the temperature to a desired temperature under reduced pressure and then inject it under pressure. It's okay. The goal is to have reasonable supersaturation conditions upon contact with the crystals in the high pressure vessel after pressurization. Finally, all of this does not have to be done in stages. It goes without saying that a series of cyclic continuous operations may be performed in which the separated mother liquor is depressurized, repressurized, and reinjected. Furthermore, in order to complete the process and more completely separate the internal crystals from the mother liquor, it is natural that existing high-pressure crystallization techniques such as squeezing, vacuum washing and melting can be employed. In the above explanation, the effects of the present invention are already clear, and the main ones are as follows.

First, the method based on temperature history requires a large amount of thermal energy and time because heating and cooling are repeated. Particle melting and cluster disappearance using pressure can be performed in a short time with less energy.

Then, when pressurizing, the viscosity of the mixture liquid phase generally increases, but nucleation is generally small and a large degree of supersaturation can be obtained, allowing for a wider range of conditions to be selected during reinjection.

Although the present invention is not limited in the least in the design and configuration of a specific device for carrying out the above-mentioned method of the present invention, typical examples of devices are also proposed as described above. Therefore, the configuration and effects will be explained based on schematic diagrams illustrating the embodiment.

FIG. 4 is an example of this, in which the high-pressure vessel 1 includes a body 2,
Consisting of a bottom cover 3 and a piston 4, the inner surface of the body 4 has a heat insulating layer 5 made of a heat insulating material such as phenolic resin.
is formed, preventing heat exchange with the outside and suppressing the formation of a temperature gradient inside the container 1. In addition, the filter for extracting the mother liquor and small particle size crystals is a wire mesh 6.
a, 6b and perforated plates 7a, 7b that support them
It consists of The stock solution supplied along line 15 is supplied or pressurized by pressurizer 11, passes through line 8 from check valve 14, and is injected into container 1 (line 18 will be described later). ). Note that 22 is a valve provided as necessary. The piston 4 is inscribed in the heat insulating layer 5 and slides up and down, and when it descends, it can be used for internal pressurization and pressure adjustment by reducing the volume inside the container 1. . The piston 4 also functions as a squeezing piston when squeezing and separating the solid and liquid in the container 1. Although the partial reduced pressure melting method was previously described, in this case, the pressure within the container 1 may be reduced by raising the piston 4. The mother liquor discharge lines 9a and 9b are connected to the back of filters placed above and below the container 1, and by setting the pressure of the interposed drainage pressure regulating valves 10a and 10b, the pressure inside the pressure container 1 is set to a predetermined pressure. The mother liquor and small-sized crystals flow out without becoming smaller and immediately enter the storage tank 12. Here, the pressure regulating valve 10 can be replaced with another device that has the function of separating the mother liquor under high pressure and does not reduce the pressure inside the container even if the pressure of the separated mother liquor is reduced. Storage tank 1
2 may be maintained under high pressure, but may also be maintained under atmospheric pressure in order to completely dissolve the effluent mixture.
Note that the present invention also includes a case where the storage tank 12 is not provided.
The obtained liquid phase mixture passes through the return line 13 and further a valve 23 (or pressure regulating valve) provided as necessary, and reaches the front of the pressurizer 11, or reaches the circulating fluid booster 11', and is pressurized again. After that, it is returned to the high-pressure container 1 via the check valve 14 or 14', but at this time, it may be injected under pressure together with the stock solution from the line 15, or it may be injected after entering the container 1. It may be pressurized to a pressure higher than desired or may be injected without mixing with fresh stock solution.

Line 18 is a seed crystal supply line, 20 indicates a nucleator or feeder, and 21 is a valve.
The line 18 also serves as a flow supply line for the stock solution, but in some cases, nuclei may be generated while flowing through the line 18 without using the nucleation or supply device 20. In this case, the entire line 18 may be cooled from the outside, or the raw material mixture coming from the line 15 may be cooled in advance. Line 8 is an injection line for the effluent mixture to be returned as described above, but if this mixture is passed through line 18 during operation, seed crystals may be generated here, which is not suitable for the purpose of the present invention. Valve 21 should remain closed during repeated cycles. Each of these described devices is a representative example of the present invention and can be used for purposes other than those described above, but the point is that the present invention can be applied as long as the device is capable of melting the effluent mixture under reduced pressure and returning it to the high-pressure container. Can be used for implementation.

〔Effect of the invention〕

Since the present invention is constructed as described above, it is possible to make the crystals grown in the high-pressure container as large and as pure as possible.

[Brief explanation of the drawing]

Figure 1 is a distribution diagram showing the principle of the present invention, Figures 2 and 3 are distribution diagrams showing the principle of the present invention.
The figure is an enlarged sectional view showing the crystalline state, and FIG. 4 is an overall conceptual diagram showing the apparatus of the present invention. 1... High pressure container, 11... Pressure machine, 13... Return line.

Claims (1)

[Claims] 1. A method for crystallizing and separating at least one specific component by applying high pressure to a raw material mixture consisting of two or more components, wherein the specific component is brought to a supersaturated state under high pressure. The resulting mixture is made into a fluid state, and after generation and/or supply of crystal nuclei consisting of the above-mentioned specific components, the crystals of the specific components are grown and increased in a high-pressure container to obtain solid-liquid coexistence. Crystals with a large particle size remain in the high-pressure vessel, while crystals with a small particle size are drawn out of the high-pressure vessel together with the liquid phase, and the pressure of the effluent mixture is reduced to a pressure lower than the solid-liquid equilibrium pressure for its composition. The grain-sized crystals are melted, and then, under repressurization, they are fed into the high-pressure container in a supersaturated state in which no crystals are precipitated, and brought into contact with the solid phase of large-grained crystals remaining in the container. A crystallization method characterized by promoting crystal growth. 2. A crystallization method according to claim 1, in which the pressure is reduced to a pressure lower than the solid-liquid equilibrium pressure of the effluent mixture composition by 50 Kg/cm ² or more when melting the small-sized crystals. 3. A crystallization method according to claim 2, in which the pressure is reduced to a pressure 100 Kg/cm ² or more lower than the solid-liquid equilibrium pressure of the effluent mixture composition when melting the small particle size crystals. 4 In claim 1, 2 or 3,
A crystallization method in which small-sized crystals are first melted by partially reducing the pressure in a high-pressure container before being extracted. 5. An apparatus for crystallizing and separating at least one specific component by applying high pressure to a raw material mixture consisting of two or more components, which pressurizes the raw material mixture,
A pressurizing device that adjusts the pressure, a transportation pipeline for the pressurized raw material, a high-pressure container that stores the raw material, and a liquid discharged through a pressure regulating valve installed after the filtration surface of the high-pressure container. a return pipe for returning the phase to the high-pressure container; further, a return liquid pressure booster is interposed in the return pipe; and a seed crystal generation or supply device is interposed in the transport pipe. A crystallizer characterized by: 6. The crystallizer according to claim 5, wherein the return liquid pressure booster also serves as a pressurizing device.