JPH0286803A - Apparatus and method for pressure crystallization - Google Patents

Abstract

PURPOSE:To improve a yield of product of pressure crystallization and to reduce the time required for the preparation of raw material into a vessel by providing freely attachably and detachably a bottomed cylindrical vessel having at least a filter in the cylindrical part of the vessel, to the inside surface side of a high pressure vessel. CONSTITUTION:The high pressure vessel is constituted of a pressure resistant cylinder 1, a cover 2 disposed freely attachably and detachably to one end of the cylinder 1, and a pressurizing mechanism 5 provided to another end of the cylinder 1. The bottomed cylindrical vessel 18 having a filter in at least its cylindrical part of the vessel is housed freely attachably and detachably to the inside surface side of the high pressure vessel. As the result, the concn. of a solid phase of liquid slurry of the raw material is not limited, so a yield of produced crystal is improved. Moreover, the time required for the prepn. of the raw material in the high pressure vessel is reduced. At the same time, required time necessary for stages from opening the vessel in order to discharge the final product to a reassembling stage of the vessel after opening, is reduced. Thus, the time required for performing one cycle of the operation is reduced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a pressure crystallizer and a pressure crystallization method.

(Conventional technology) Pressure crystallization has great potential for application to raw material systems that are difficult to separate using conventional distillation or cooling crystallization, is easy to obtain high-purity products, and has high It is a separation and purification technology that has been attracting a lot of attention as the chemical industry has become increasingly refined in recent years because of its high yield and low energy consumption.

An overview of such pressure crystallization method and pressure crystallizer is given in, for example, Kagaku Kogyo Vol. 1.50. No, 5. P331 335
Described in 'Overview of Pressure Crystallization Method and Apparatus'. This will be explained below.

FIG. 8 shows a process flow diagram of the pressure crystallization method. Part 9 shows a side sectional view of the pressure crystallizer.

As shown in these figures, the pressure-resistant cylindrical body (1) is provided with a lid body (lower rim (2)) at the bottom, and the piston (5) is moved into the cylindrical body (1) by the operation of the hydraulic unit (3). ), and these constitute a high-pressure container.A cylindrical filter 01 is fixedly provided on the inner surface of the container (as shown in FIG. 9), and , a crystallization chamber (4) is formed therein.

The crystallization chamber (4) and the drain tank (6) are connected to a pressure reducing mechanism θ
(1) and is connected by a liquid discharge pipe (9) via a valve (It). Further, the crystallization chamber (4) and the pre-crystallizer (7) are connected to each other by a liquid injection pipe via a raw material supply pump (8) and a valve θ.

The raw material is fed from the raw material tank θ to the pre-crystallizer (7) to generate seed crystals for pressure crystallization. This is because when raw materials without seed crystals are subjected to pressure crystallization, the supersaturation pressure is generally relatively high, typically several hundred atmospheres or more, and high pressure is required for initial crystal formation. This is because there is a risk that the slurry containing seed crystals will be supplied, which has the advantage that not only is there no need to worry about such supersaturation pressure, but crystal growth can be expected without nucleation due to pressurization.

Next, the raw material is transferred to the crystallization chamber (4) via the piping θ (valve 02).
). When the crystallization chamber (4) is filled with the raw material, the liquid begins to flow out through the overflow pipe (05) having an opening at the tip of the piston.This is detected and the valve (021)
Close O[9 and start pressurizing with the piston (5). When the raw material liquid is pressurized, crystallization of a specific substance in the raw material progresses, and the inside of the crystallization chamber (4) is in solid-liquid equilibrium under high pressure. state.

The solid produced at this time is generally a substance of extremely high purity. In addition, due to the latent heat of solidification generated as solidification progresses,
Although the temperature inside the crystallization chamber (4) increases, in the pressure crystallization method, generally no cooling is performed to prevent this temperature increase, and a method of adiabatically pressurizing is adopted. The temperature reached after temperature rise, that is, the temperature at which solid-liquid separation starts, affects the purity and yield of the product.
This is adjusted by taking into account the specific heat, latent heat of solidification, etc. of the raw material mixture and adjusting the temperature of the supplied liquid.

Next, the pressure is increased to a predetermined pressure, and when the predetermined solid-liquid ratio is reached, valve 00 is opened and the hydraulic unit (3) is connected to the piston (
If the piston continues to descend while maintaining the pressure in the crystallization chamber (4) by maintaining the pressure acting on the crystallization chamber (4),
The crystal grain groups within are squeezed under pressure, and the remaining liquid between the crystal grains undergoes a so-called "squeezing action" and is discharged to a drain tank (6).

As the piston (5) continues to descend further, the crystal grains are formed into one large lumpy solid product along the shape of the crystallization chamber (4). When the liquid is almost completely separated from the solid in this way, the liquid phase pressure and force in the crystallization chamber (4), which is connected to the drain tank (6) under atmospheric pressure, gradually decreases. As a result, the crystal surface is partially melted, so-called "sweat washing" is performed, and the bulk solid product is purified.

When the pressure of the drained liquid discharged from the crystallization chamber (4) drops to a predetermined pressure, the piston (5) stops descending, and at the same time the piston begins to rise, the cylinder body (+) also rises. Solid products are placed on the lower lid (2) and placed in the container (1).
). This is taken out by a product take-out device (not shown), the cylindrical body (1) is lowered, and the lower lid (
2), then return to the raw material injection process and repeat the same process. Before injecting the raw material, purge the remaining liquid in the overflow pipe θω with a gas inert to the product, such as nitrogen gas, to prepare for full liquid detection during injection in the next process. I'll keep it.

By repeating the above steps, products are produced continuously.

(Problems to be Solved by the Invention) As described above, the conventional pressure crystallizer includes a pressure-resistant cylinder, a removable lid disposed at one end of the cylinder, and a lid at the other end of the cylinder. It has a high-pressure container configured with an internal pressure mechanism (piston) disposed on the side, and a cylindrical filter is fixedly provided on the inner surface of the high-pressure container. Furthermore, the conventional pressure crystallization method is carried out using the above-mentioned apparatus, in which a raw material (slurry liquid) containing seed crystals is injected from piping through a valve into the high-pressure vessel. The mixture is pressurized to form a solid product of specific components, and the product is removed from the high-pressure container.

However, since the raw material liquid contains seed crystals, it is a slurry liquid in which solid and liquid coexist. The higher the in-phase concentration of this slurry, the higher the yield, but it is limited by the feeding capacity of the bomb, and its upper limit is generally about 20 to 25%. Therefore, there is a problem that the product yield is limited.

Further, slurry liquid has a higher viscosity than liquid, and since such slurry liquid is injected from piping through a valve, there is a problem that it takes a long time to inject it into the high-pressure container.

Furthermore, the raw material liquid is often pre-cooled to form a slurry liquid containing seed crystals. Therefore, the temperature difference between the slurry liquid and the high-pressure container is relatively large, and the difference is usually a few degrees to a few degrees. Furthermore, it takes a long time to inject into the high-pressure container. Therefore, the temperature of the slurry increases when it is injected into the high pressure container. Therefore, there is a problem that the solid phase concentration of the slurry liquid decreases at the time when pressure is applied to start pressure crystallization, resulting in a decrease in product yield.

Furthermore, in order to take out the product formed in the high-pressure container, it is necessary to raise the piston and the high-pressure container and separate it from the lid. After taking out the product on the lid, in order to carry out the next injection process, it is necessary to lower the high-pressure container and attach it to the lower lid.

It is desired to shorten these times.

The present invention has been made with attention to these circumstances, and its purpose is to solve the above-mentioned problems of the conventional methods, and to prevent the solid phase concentration of the raw material slurry from being uniform and to achieve a uniform concentration. In addition, the time required to prepare raw materials in the high-pressure container can be improved, and the time required to prepare raw materials in the high-pressure container can be reduced, as well as the process from opening the high-pressure container to take out the product to the assembly process of the high-pressure container after taking out the product. It is an object of the present invention to provide a pressure crystallizer and a pressure crystallization method that require less time and therefore less time per cycle.

(Means for Solving the Problems) In order to achieve the above object, a pressure crystallization apparatus and a pressure crystallization method according to the present invention have the following configuration. That is, the pressure crystallizer according to the present invention includes a pressure-resistant cylinder, a removable lid disposed at one end of the cylinder, and an internal pressure mechanism disposed at the other end of the cylinder. A filter-equipped container having a cylindrical shape with a bottom and having a filter in at least the cylindrical portion is removably provided on the inner surface of the high-pressure container. This is a pressure crystallizer. Further, in the pressure crystallization method according to the present invention, a mixture of two or more components including a specific component is placed in a filter-equipped container having a cylindrical shape with a bottom and a filter at least in the cylindrical portion, and the filter Place the attached container inside the high pressure container,
Pressurizing the mixture in the high-pressure container to form a solid-liquid coexistence state, then discharging the liquid phase out of the high-pressure container to form a solid product of a specific component in the filter-equipped container, This is a pressure crystallization method characterized in that the solid product is obtained by removing the filter-equipped container from the filter-equipped container after the filter-equipped container is taken out of the high-pressure container.

(Function) As explained above, the pressure crystallizer according to the present invention has a cylindrical shape with a bottom attached to the inner surface of the high-pressure container, and a filter-equipped container having at least a filter in the cylindrical portion can be detachably attached. I am trying to set it up. Therefore, this filter-equipped container can be taken in and out of the high-pressure container as needed. Also,
The filter has the function of allowing liquid to pass through when it is pressurized to a high pressure, and can be made so that it does not allow liquid to pass through under atmospheric pressure. Therefore, this container with a filter can be a container that does not leak liquid under atmospheric pressure, and can have a filter function under high pressure.

In the pressure crystallization method according to the present invention, a mixture is placed in a filter-equipped container having the above-mentioned functions, and the filter-equipped container is placed in a high-pressure container. With this operation,
Raw materials will be deposited into the high-pressure container. This can be done without the use of a pump, so the in-phase concentration of the raw slurry is not limited. Furthermore, since it can be carried out without using piping or valves, the time required to prepare the raw material into the high-pressure container is extremely shortened.

Further, after the raw materials are prepared in the high-pressure container, the mixture is pressurized in the high-pressure container to form a solid-liquid coexistence state, and then the liquid phase is discharged out of the high-pressure container. . At this time, the filter-equipped container has a filter in its cylindrical portion, so only the liquid passes through the filter. Therefore, solid-liquid separation occurs, and as a result, the solid state of the specific component is contained in the filter-equipped container. Can be formed into products.

After the solid product is formed, the filter-equipped container containing the product is taken out of the high-pressure container, and then the solid product is obtained by removing it from the filter-equipped container.

On the other hand, it is easy to carry out the operation of putting the mixture into another filter-equipped container in parallel with the process operations up to the step of removing the filter-equipped container. In this way, immediately after removing the filter-equipped container, another filter-equipped container is placed in the high-pressure container without waiting until the removal of the solid product from the container is completed.
Preparation of raw materials into high pressure vessels may be performed. Therefore, the time required from the process of opening the high-pressure container to take out the product to the process of assembling the high-pressure container after taking out the product can be shortened.

Regarding containers with filters, it is desirable to provide means for extruding solid products at the bottom.
For example, as shown in FIG. 1, the extrusion jig O!
All you have to do is set it up.

Further, the filter has a filter in at least the cylindrical part, and the bottom part may also be a filter if necessary.
Further, the filter-equipped container may be of an integrated type, or the bottom portion (22) may be separable as shown in FIG.

In addition, if the filter is thin and its strength is low, it is recommended to provide a protector with a liquid flow path around the container with a filter. Examples of containers with a filter having such a protector are shown in Figure 3 and FIG. Shown in Figure 4.

What is shown in Fig. 3 is a protective body 1 having a large number of slits.
It is a container with a filter provided with a width of 2 m, and during pressurization, liquid can pass through the filter and be discharged through the slit (21). Moreover, FIG. 4 shows the main part of a container with a filter provided with a protector having a sealing gasket. This sealing gasket (23) is fitted into a hole (24) provided in the protector, and closes under atmospheric pressure as shown in Figure 5, and when pressurized, it closes as shown in Figure 6. It can be opened as shown. By using a protector having such a sealing gasket, even if the filter is extremely thin, it can become a container that does not leak liquid under atmospheric pressure, and can have a filter function under high pressure.

(Example) Embodiments according to the present invention will be described with reference to the drawings.

SuJflLfLL FIG. 7 shows a pressure crystallizer according to an embodiment of the present invention.

This pressure crystallizer is a pilot plant with a crystallization capacity of 1.51. As shown in this figure, a pressure-resistant cylinder (
1), a removable lid (2) disposed at one end of the cylinder, and an internal pressure mechanism disposed at the other end of the cylinder; A container Om with a filter, which has a cylindrical shape with a garden and has a filter in the cylindrical portion, is detachably provided on the inner surface of the high-pressure container. This filter-equipped container is equipped with an extrusion jig 0ω at the bottom, similar to the one shown in FIG.

Using the above pressure crystallizer, the components of P-cresol were
02. A raw material solution (isomer mixture) for pressure crystallization separation containing 20x of ea-cresol component was subjected to pressure crystallization separation using P-cresol as the target product in the following manner.

First, the raw material liquid was pre-cooled to 15°C in a pre-cooling tank. The slurry concentration after pre-cooling was 18.3%. Next, this raw material liquid (slurry) was put into a container with a filter, and the container with a filter was placed in a high-pressure container. The body (1) was lowered and attached to the lower lid (2). By this operation, the raw material (4) is prepared in the high pressure container. The raw material preparation time was reduced by 30x compared to the conventional method.

After the above installation, the mixture is pressurized to 1500 atmospheres by the piston, then the valve of the liquid discharge pipe (9) is opened, and the piston (5) continues to descend while maintaining this pressure to compress the mixture under pressure, The liquid phase was discharged out of the high pressure vessel. The lowering of the piston (5) was continued to form - large chunks of solid product. After that, the piston (5) stops descending, and the piston (5) starts rising, and the pressure-resistant cylinder (1)
It also increased. As a result, a product was formed in the filter-equipped container a8).

Next, the filter-equipped container marked O was taken out of the high-pressure container. On the other hand, before this removal was completed, another container with a filter was separately prepared into which pre-cooled raw material liquid (slurry) was poured.

After taking out the filter-equipped container 0111, the solid product is removed from the filter-equipped container 0111, and another separately prepared filter-equipped container is placed on the lid (2),
The pressure-resistant cylinder (1) was lowered and attached to the lower lid. After installation, pressurization using the piston (5) was started, and the same operation as the first time was performed. The time required from the process of opening the high-pressure container to take out the product to the process of assembling the high-pressure container after taking out the product was reduced by 10% compared to the conventional method.

The product was produced by repeating the above steps. As a result, the time per cycle was reduced by 15% compared to the conventional method. The product yield of P-cresol is 3
It was 8%.

Actual Cresol raw material liquid having the same composition as in Example 1 was pre-cooled to 5°C in a pre-cooling tank. The slurry concentration after pre-cooling was 40%. Using the same pressure crystallizer as in Example 1, the same steps were repeated to produce a product.

As a result, the product yield of P-cresol was 43%. This is extremely high compared to the case of Example 1, but this is because the slurry concentration is high.

In addition, the conventional apparatus and method cannot feed the slurry into the high-pressure container when the slurry concentration is 25% or more.
Pressure crystallization could not be performed, which limited the yield. On the other hand, in Example 2, even when the slurry concentration was 40%, pressure crystallization could be performed without any problem, and therefore the yield could be significantly improved.

Note that the time per cycle was the same as in Example 1.

(Effects of the Invention) According to the pressure crystallizer and pressure crystallization method according to the present invention, the solid phase concentration of the slurry liquid of the raw material is not limited, and therefore the yield can be improved. In addition to reducing the time required to prepare raw materials, the time required from opening the high-pressure container to take out the product to assembling the high-pressure container after removing the product is also shortened, resulting in a reduction in time per cycle. It will be shortened.

[Brief explanation of drawings]

Figure 1 is a side sectional view of a container with a filter equipped with an extrusion jig, Figure 2 is a sectional side view of a container with a filter whose bottom can be separated, and Figure 3 is a side sectional view of a container with a filter provided with a protector having many slits. A side sectional view of a container with a filter, FIG. 4 is a side sectional view showing the main part of the container with a filter provided with a protector having a sealing gasket, and FIG. 5 is a view showing the sealing gasket in a closed state. FIG. 6 is a diagram showing the sealing gasket in an open state, FIG. 7 is a diagram showing the pressure crystallizer according to the embodiment, FIG. 8 is a schematic diagram showing the process flow of the conventional pressure crystallization method, and FIG. FIG. 9 is a side sectional view of a conventional pressure crystallizer. (1) - Pressure-resistant cylinder (2) - Lid (3) - Hydraulic unit (4) - Crystallization chamber (5) - Piston (6)
- Drainage tank (7) - Pre-crystallizer (8) - Raw material supply pump (9) - Liquid discharge piping q - Freezing pressure mechanism
Qi) Surface 0 - Valve 09 - Liquid injection pipe Round - Raw material tank θ Overflow pipe 07) - Cylindrical filter 08) - Container with filter Og) - Extrusion jig QTo Protective body with many slits (21L-Slit (22)-Bottom (23)--
Seal packing (24) - Hole Patent applicant Kobe Steel Co., Ltd. Agent Patent attorney Akira Kaneki - Figure 1 Figure 3 Figure 2 Figure 4 Figure 5 Figure 6 ○ ■ Figure 8 Figure 7 Figure 9

Claims (2)

[Claims] (1) It has a high-pressure container composed of a pressure-resistant cylinder, a removable lid placed at one end of the cylinder, and an internal pressure mechanism placed at the other end of the cylinder. A pressure crystallizer, characterized in that a filter-equipped container having a cylindrical shape with a bottom and having a filter in at least the cylindrical portion is removably provided on the inner surface of the high-pressure container. (2) A mixture consisting of two or more components including a specific component is placed in a filter-equipped container having a cylindrical shape with a bottom and a filter at least in the cylindrical portion, and the filter-equipped container is placed in a high-pressure container. , pressurize the mixture in the high-pressure container to form a solid-liquid coexistence state, and then discharge the liquid phase out of the high-pressure container to form a solid product of a specific component in the filter-equipped container. . A pressure crystallization method characterized in that the solid product is obtained by removing the filter-equipped container from the filter-equipped container after the filter-equipped container is taken out of the high-pressure container.