JPH0412161B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has been improved to prevent the precipitation of crystals in high-pressure piping for discharging mother liquor, and to smoothly carry out pressure crystallization separation operations. This relates to pressure crystallization separation method.

[Prior art] The pressure crystallization method is a method in which a raw material consisting of a liquid phase or slurry containing multiple components is introduced into a high-pressure container, and the mother liquor discharge pipe is closed and the raw material is heated to a high pressure (for example, 1000
This is a method of accelerating crystallization of a specific component by applying high pressure (exceeding atmospheric pressure), and by this operation, a solid-liquid mixed state consisting of crystals of the specific component and residual liquid (mother liquor) is obtained. At that point, the mother liquor discharge pipe is unblocked, piston pressure is applied to the above-mentioned solid-liquid coexistence state, the mother liquor is discharged out of the system via the filter, and the remaining solid phase is squeezed to further separate the solid and liquid. By discharging the gas, high-purity specific components can be recovered.

For example, FIG. 4 is a schematic flow diagram showing a pressure crystallizer, in which the raw material mixture A is cooled to an appropriate temperature in a preliminary cooling tank 1, and then passed from a slurry pump 2 to a raw material supply pipe _L1 to the pressure crystallizer. 3 into the high pressure chamber 4. After driving the piston 5 to pressurize the raw material in the high pressure chamber 4 and increase or generate crystals of specific components in the raw material, the liquid phase component (mother liquor) is squeezed from the screen through the mother liquor discharge pipes L ₂ and L ₃ .・The crystals of the specific component remaining in the high pressure chamber 4 are recovered after the discharge. In the figure, V ₁ ,
V ₂ , V ₃ , V ₄ , V ₅ are on-off valves, N is a discharge nozzle, 6
7 indicates a drain tank, and 7 indicates a pressurizing unit.

The steps of the pressure crystallization method described above are as follows.

: Close the on-off valve V ₂ and open the on-off valve V ₁ to supply the raw material mixture into the high pressure chamber 4 of the pressure crystallizer 3. : Close the on-off valves V ₁ and V ₃ and operate the piston 5. A process of applying high pressure to the raw material mixture to increase or increase the generation of crystals of a specific component: Opening the on-off valves V ₂ and V ₃ and draining the mother liquor in the high pressure chamber 4 via the screen and the mother liquor discharge pipes L ₂ and L ₃ : A process of operating the piston 5 to squeeze out the mother liquor remaining in the high pressure chamber; : A process of opening the high pressure chamber to take out crystals of a specific component.

After completing the above steps, the process returns to the next step, and by repeating this operation, the specific components are continuously separated and recovered. FIG. 5 conceptually shows the pressure change over time during the above series of steps.

[Problems to be solved by the invention] The present inventors have been conducting research on the practical application of pressure crystallization separation method in accordance with the above-mentioned method, but have encountered the following problems during the research process. . That is, the problem was that the mother liquor discharge pipes L ₂ and L ₃ were clogged, and continuous operation was occasionally interrupted. The present invention has been made in view of these problems, and includes:
The purpose is to provide a pressure crystallization separation method that can smoothly carry out the series of repeated operations without causing the problem of pipe clogging.

[Means for Solving the Problems] The structure of the method of the present invention that has achieved the above object is that in a pressure crystallization separation method that concentrates and purifies a specific component using pressure as a variable, a pressure increasing step in a high pressure chamber is used. Open the nozzle of the mother liquor discharge pipe from the beginning or at any point during the pressurization process, raise the pressure in the high pressure chamber to a predetermined pressure while letting the mother liquor flow out, form crystals of a specific component in the high pressure chamber, and increase the pressure or The gist of this method is that the mother liquor is further separated at a pressure close to that level and then squeezed.

[Operations and Examples] In order to solve the above-mentioned problems found in the prior art, the present inventors first investigated the cause of their occurrence. As a result, the following facts have become clear. That is, the above-mentioned method adopted in the conventional method
In a particular step of the above steps, the pressure inside the high-pressure container is released and the liquid phase component is squeezed out.
At this point, the amount of liquid phase components remaining in the high-pressure container is small, and when adding an operation to self-clean the surface of the solid phase by melting the surface of the solid phase under reduced pressure, some of the specific components may be removed. is melted and mixed into the mother liquor, so the liquid phase component discharged in the final process of mother liquor discharge has a considerably high concentration of specific components. The extraction (process) of specific component crystals is
The high concentration liquid phase component flows from the high pressure chamber 4 in Fig. 4 to the on-off valve.
After the mother liquor discharge pipes (hereinafter simply referred to as drain pipes) up to V ₂ and V 3 are carried out while L ₂ and L ₃ remain full, the raw material mixture is subsequently supplied ₍ process),
Pressure crystallization (process) and separation and discharge of the mother liquor (process) are performed, but an on-off valve V ₂ ,
Since the drain pipes L ₂ and L ₃ up to V ₃ communicate with the high pressure chamber 4, the high pressure applied to the high pressure chamber 4 is substantially directly applied to the drain pipes L ₂ and L ₃ . come. On the other hand, the drain pipes L ₂ and L ₃ are filled with the liquid phase component having a high specific component concentration squeezed out from the high pressure chamber 4 at the end of the compression process as described above, so that these liquid phase components are extracted from the high pressure chamber 4 at the end of the compression process. It is thought that when pressure is applied at the same time, specific components crystallize in the drainage pipes L ₂ and L ₃ and cause pipe clogging. If this phenomenon occurs, it becomes impossible to separate and discharge the mother liquor (process), so take measures such as stopping the operation and heating the pipes L ₂ and L ₃ to melt the precipitated crystals in the pipes. As a result, productivity will drop significantly.

Therefore, as we proceeded with various studies to solve these problems, we decided to open the drain pipe nozzle from the beginning of the pressure increase process in the high pressure chamber or at any point during the pressure increase process and drain the mother liquor. If a method is adopted in which the pressure in the high-pressure chamber is increased to a predetermined pressure to precipitate and increase the crystals of a specific component in the high-pressure chamber, and the mother liquor is separated at or near that pressure and then squeezed, the above problem can be solved. I found that the points were resolved perfectly.

That is, FIG. 1 is a schematic process diagram illustrating the pressure crystallization separation method according to the present invention, and the basic configuration of the apparatus used is the same as the example shown in FIG.
Identical parts will be given the same reference numerals and redundant explanation will be omitted. Moreover, FIGS. 2 and 3 conceptually show pressure changes when implementing the present invention. The present invention is different from conventional methods, and its most important feature is that the nozzle N of the drainage pipe is opened from the beginning of the pressure increase process in the high pressure chamber or at any point during the pressure increase process, and the mother liquor is allowed to flow out. However, the pressure inside the high-pressure chamber is raised to a predetermined pressure. FIG. 2 shows an example in which the nozzle N is opened at point P during the pressure increase, and FIG. 3 shows an example in which the nozzle N is opened from the beginning of the pressure increase step, and each subsequent step is the same as in the conventional example. In this way, if the nozzle N installed in the drain pipe is opened from the beginning of the pressure increasing process or in the middle of the pressure increasing process, the mother liquor will begin to be discharged as soon as the nozzle N is opened, and the mother liquor will be discharged from the high pressure chamber 4 at the end of the previous operation. _The high-concentration liquid phase components remaining filled in _the drain pipes L ₂ and L ₃ up to N The inside of the pipes L 2 and L ₃ is replaced by the mother liquor separated and discharged from the pipes L ₂ and L 3 . Therefore, even if the pressure inside the pipes L ₂ and L ₃ becomes high thereafter, there is no fear that a specific component will crystallize in the pipes, and the problem of pipe clogging is eliminated.

As can be easily understood from the above explanation, the timing when the nozzle N is opened during the pressure increase (P in Figure 2) is when the high concentration liquid phase components remaining in the drain pipes L ₂ and L ₃ are removed. It is sufficient to set the timing before the crystallization of a specific component in the liquid phase component starts, and the timing can be controlled by the operating temperature, the concentration of the specific component in the liquid phase component, etc. If the method of opening the nozzle N from the beginning of the process is adopted, the above-mentioned work will be completely unnecessary. In this case, if the nozzle opening is too large at the start of pressure increase, the rate of pressure increase in the high pressure chamber will slow down, and some of the specific components in the raw material mixture will remain uncrystallized and be discharged together with the mother liquor, reducing the recovery rate. To avoid this risk, we set the opening of nozzle N to a small value, and adjust the opening while checking the time when the high concentration liquid phase component in drain pipes L ₂ and L ₃ has been replaced with mother liquor. By performing operations such as increasing the size, the decrease in recovery rate can be minimized. However, in reality, since the initial outflow pressure is low, the outflow amount is extremely small, and if the hydraulic capacity is large, it will take a short time to reach the maximum pressure, so there is often no need to adjust the nozzle opening.

In any case, in the present invention, the discharge of the mother liquor is started before the crystals of the specific component increase due to pressurization, and it cannot be denied that recovery loss of the specific component occurs. However, if the nozzle diameter is appropriately set according to the performance of the pressurizing device, the pressure can be increased to a predetermined level in a few seconds, and the recovery loss can be suppressed to an almost negligible level.

[Effects of the Invention] The present invention is configured as described above, and its effects can be summarized as follows.

(1) There is no risk of specific components crystallizing in the drain pipe and clogging the pipe, and a series of repeated crystallization separation operations can be carried out smoothly.

(2) Since the on-off valve of the drain pipe can be omitted and the drain nozzle alone can be used, the structure of the drain pipe is not only simplified, but also the operability is improved.

[Brief explanation of drawings]

FIG. 1 is a schematic flow diagram showing an embodiment of the present invention;
Figures 2 and 3 are conceptual diagrams showing how the operating pressure changes over time when implementing the present invention, Figure 4 is a schematic flow diagram showing the conventional method, and Figure 5 shows how the operating pressure changes over time when implementing the conventional method. It is a conceptual diagram showing a change. 1: Pre-cooling tank, 2: Feed pump, 3: Pressure crystallizer, 4: High pressure chamber, 5: Piston, 6: Discharge tank, 7: Pressurizing unit, _V1 to _V5 : Opening/closing valve,
L ₁ : Raw solution supply pipe, L ₂ , L ₃ : Mother liquor discharge pipe (drainage pipe), N: Discharge nozzle.

Claims (1)

[Claims] 1. In the pressure crystallization separation method that uses pressure as a variable to concentrate and purify specific components, the nozzle of the mother liquor discharge pipe is opened from the beginning of the pressure increase process in the high pressure chamber or at any point during the pressure increase process, and the mother liquor is allowed to flow out. A pressure crystallization separation method characterized by increasing the pressure in a high-pressure chamber to a predetermined pressure to form crystals of a specific component in the high-pressure chamber, and further separating the mother liquor at or near the pressure, followed by compression.