JPS6134844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting a liquid component from a high-pressure container by applying pressure to a solid-liquid coexistence state reached by high-pressure crystallization and squeezing the solid-liquid coexistence state under high pressure.

In the high-pressure crystallization method, a raw material such as a mixed liquid or slurry consisting of multiple components is introduced into a high-pressure container equipped with a filter, and high pressure is applied to the raw material such as the mixed liquid or slurry to crystallize specific components. This is a way to promote this. By this operation, a state is obtained in which the crystals of the specific component (hereinafter sometimes referred to as the captured component) and the liquid of the remaining liquid phase component (hereinafter sometimes referred to as the removed component) are mixed. Therefore, the outlet drain pipe is unblocked, pressure is applied to the solid-liquid coexistence state, the liquid removed component is discharged from the system via the filter, and then the lid of the high-pressure container is opened or the container itself is closed. The assembly is released, and the solid collection component remaining in the container is taken out of the container as it is or after being dissolved and used as a product. In other words, if the pressure crystallization procedure is divided into process units,
The above steps can be roughly divided into the following steps: raw material introduction, pressure crystallization, straining/squeezing, and solid extraction, but all of them involve considerable high pressure, so the widely used temperature crystallization technique is directly applied. However, various problems must be overcome in each step before the high-pressure crystallization method can be commercially implemented.

The over-squeezing/squeezing process according to the present invention also has the following problems. In other words, straining/squeezing occurs between the pressure crystallization process and the solid extraction process,
A special circumstance is that the over-squeezing and squeezing operations themselves are carried out under high pressure. Therefore, unlike the general temperature crystallization method, it is not possible to perform the crystallization operation and the filtration/squeezing operation separately and independently using containers or equipment suitable for each. It must be understood that pressing is carried out using a common container or device under conditions that are interrelated with each other but cannot be said to be completely independent. Therefore, even in the straining/squeezing process, pressure crystallization is still in progress. For example, if excessive squeezing pressure is suddenly applied, the solids tend to become excessively compacted at the front of the filter, resulting in an increase in overresistance. come,
Therefore, there is a risk that the removed components may remain or some of the removed components may solidify as a result of the compaction, leading to a decrease in the purity of the collected components. Furthermore, if the final squeezing pressure is maximized, it may block the outflow of minute liquid phase components remaining inside or cause damage to the filter structure. Therefore, the present inventors set the standard of reducing the liquid pressure after passing through the filter (the discharge pressure of the removed components), and if necessary, further reduced the unseparated mother liquor (liquid removed components remaining in the pressure vessel). ) by controlling the pressure so as not to accumulate, the surface of the solid collecting component that is compacted on the front surface of the filter is melted, improving the purity of the collecting component crystal itself and promoting liquid discharge. The technology to be achieved has already been completed, and has already been published in JP-A-54-52678 and JP-A-54-52678.
54-53362.

The present invention was made as a result of studying the actual situation of the straining/squeezing process from another perspective, and as mentioned above, the pressure crystallization and straining/squeezing are performed in the same container or device, and the straining/squeezing is carried out under pressure. The purpose is to eliminate as much as possible the various difficulties that may arise due to the fact that the crystallization process is carried out under considerably high pressure, and is particularly suitable for products containing scavenging components. As long as the purity is not substantially reduced,
By avoiding excessive loads being applied to the solids of the collected components, we have established a compression separation method that can protect internal structures such as filters without imposing unnecessary loads on them. This is the purpose.

The compression separation method of the present invention that satisfies the above objectives is as follows:
In the step of further squeezing the solid component after most of the liquid removed component has been filtered out and taking out the removed component out of the filter, the pressure of the piston for squeezing is lowered stepwise or continuously to remove excess of the solid component to be collected. The purpose is to suppress the pressure load.

FIG. 1 is a pressure change diagram when the present invention is not implemented, where P _p is the pressure corresponding to the piston load (herein referred to as piston pressure),
Approximately constant pressure is applied from the beginning to the end of the straining and squeezing process. On the other hand, P _l is the liquid pressure behind the filter (on the atmospheric pressure side) and indicates the pressure inside the drain pipe before being taken out to atmospheric pressure. That is, when entering the straining/squeezing step, the closure of the outlet drain pipe is released, and the piston is lowered to apply piston pressure to the workpiece in a solid-liquid coexistence state. The liquid appears on the back side of the filter with the same pressure as _p (liquid pressure P _l ), and is discharged into the atmosphere through the drainage pipe, but soon most of the liquid removed components in the material to be treated are passed through, and the inside of the high-pressure chamber is no longer visible. It will be filled with the collected components in the form of a hanging solid. However, microscopic observation shows that a considerable amount of mother liquor remains between each crystal of the scavenging component, and if the filtration ends at this stage, the liquid removed component will be trapped between each crystal of the scavenging component in an inclusion state. Naturally, the purity of the specific component in the collected solid will be low. Therefore, in this state, the filter is not stopped and the piston continues to be lowered to squeeze out the solid collected components, but in this case, the amount of liquid passing through the filter is smaller than that in the previous stage. From then on, the hydraulic pressure P _l gradually decreases as shown in Figure 1,
The differential pressure P _s with respect to the piston pressure P _p gradually increases. However, since the piston pressure P _p is constant and the liquid pressure P _l is decreasing, the differential pressure P _s can be thought of as the pressure acting on the solids remaining before the filter, and this solid This means that the pressure P _s applied to will gradually increase. Therefore, under the pressure action state shown in Fig. 1, all of the piston pressure acts on the solid at the final stage of compression, and a filter (generally speaking, a filter is used for compression by the piston) is placed around the solid. (The filter is arranged in a direction perpendicular to the direction of the compressed solid, so that the liquid can easily pass between the layers of the compressed solid and be discharged.) Friction occurs between the filter and the inner and outer surfaces of the filter are subjected to a high differential pressure. This poses a problem of overloading the filter, its support, and various other structures, which may have an adverse effect on them. In particular, it significantly shortens the life of the filter, which not only increases maintenance costs, but also causes problems in that the production line must be stopped while parts are replaced, reducing productivity. In addition, there is also an element in which the solid components that come into contact with the filter are melted by the frictional heat caused by the friction (an element in which minute solids flow out from the filter gap), and these are immediately passed behind the filter to collect specific components. There is also the problem that the disadvantage of a decrease in the rate of compression occurs when pressing too much pressure
Occurs when _s is given.

Therefore, in the present invention, the piston pressure P _p is reduced by decreasing the piston pressure P _p stepwise as shown in _FIG . The difference in liquid pressure P _l (pressure P _s applied to the solid) is suppressed from becoming excessive, and the occurrence of the above-mentioned adverse effects is prevented. The timing at which the piston pressure starts to decrease and the degree to which it decreases vary depending on the structure of the high-pressure crystallizer, the type of equipment material, the degree of crystallization operating pressure and squeezing pressure, and the properties of the raw materials and crystals being handled. As for the point at which the piston pressure starts to decrease, one example is a method in which the above-mentioned point in time when the solid component flows out is detected and the pressure is decreased from the point at which the symptom appears. This is because the molten liquid of a specific component melted by frictional heat immediately passes through the filter and acts in the direction of increasing the liquid pressure P _l (see Figure 4), so seize this point and lower the piston pressure. If so, at least the overload on the filter can be suppressed to a minimum. Although the subsequent drop in piston pressure can also be controlled freely, for example, as shown in FIG. 5, a method may be adopted in which the pressure is reduced in stages every time a temporary increase in the hydraulic pressure P _l is observed. However, from an industrial perspective, when using specific raw materials and specific equipment, P
The behavior of _p and P _l is almost the same and can be operated based on preset conditions.

Next, as for the method of lowering the piston pressure, any method can be adopted depending on the design of the pressurizing device (for example, a hydraulic circuit). The figure shows an example of the continuous reduction method. In these figures, 1 is a relief valve designed with a large set value, 2 is a relief valve designed with a small set value, 3 is a solenoid valve, 4 is a check valve, and 5 is a relief valve designed with a small set value.
is a variable setting value type relief valve. Although the present invention uses a piston-cylinder type high-pressure device for convenience, there is no reason why the structure of the device is limited to this, and it can be adopted to any structure including a high-pressure device having an external pressurizing mechanism.

Since the present invention is constructed as described above, it has become possible to collect a specific component as a solid with suitable purity and collection rate without overloading the high-pressure vessel structure.

[Brief explanation of the drawing]

Figure 1 is a pressure control diagram in the conventional example, and Figures 2 to 5
The figure shows a pressure control diagram in an example of the present invention, and FIGS. 6 and 7 show hydraulic circuit diagrams suitable for changing piston pressure.

Claims (1)

[Claims] 1. When squeezing the solid-liquid coexistence state under high pressure reached by high-pressure crystallization and extracting the liquid component from the high-pressure container, the solid component is further squeezed after most of the liquid component has passed through. A squeezing method in high-pressure crystallization, characterized in that in the step of extracting the liquid component out of the filter, the pressure is lowered stepwise or continuously to suppress the load of excessive pressure on the solid component.