JP7599132B2 - Continuous liquid-liquid separator and continuous liquid-liquid separation method - Google Patents

Description

The present invention relates to a continuous liquid-liquid separator and a continuous liquid-liquid separation method that continuously separates a two-phase liquid consisting of at least two components that are completely immiscible with each other and separate into two phases, a light liquid and a heavy liquid, according to the specific gravity of each component.

In the past, chemical synthesis processes were carried out using a batch method in which reactions and separation/purification were repeated in multiple stages, but this manufacturing method produced a large amount of waste and had a low product yield.In recent years, therefore, in order to reduce the environmental impact and improve cost competitiveness, efforts have been made to switch to a flow method in which multiple stages of reactions and separation/purification of reaction products are carried out continuously, achieving both reduced waste and high yields, as well as aiming for automated operation and compactness.
As a means for separating and purifying a product in a flow method, a prior art is known in which a liquid to be extracted containing the product is contacted with an extracting agent that is immiscible with the liquid to be extracted, and a two-phase liquid consisting of an extracting liquid containing the product and the liquid to be extracted is separated into liquid-liquid separation according to the specific gravities of the liquids.

For example, Patent Document 1 describes a continuous liquid separation device that separates a mixture of liquids with different specific gravities that flows into a chamber from a liquid inlet, and then discharges the upper and lower liquids from an upper and lower outlet, respectively, and that monitors the position of the interface in the chamber using an interface detection means and controls a flow rate adjustment means provided on at least one of the outlet paths to maintain the position of this interface at a predetermined position.

Patent Document 2 also describes a continuous liquid-liquid separator that separates a two-phase liquid into a light liquid and a heavy liquid, discharging the light liquid from an upper light liquid outlet and the heavy liquid from a lower heavy liquid outlet, in which a heavy liquid permeable porous membrane is installed at the heavy liquid outlet, and the heavy liquid permeable porous membrane has a material and pore size that generates a heavy liquid retention force that prevents the light liquid from passing through even when there is a pressure difference between the upstream and downstream of the heavy liquid permeable porous membrane, and the light liquid outlet is equipped with a light liquid permeable porous membrane that has a pore size and membrane area such that the pressure upstream of the heavy liquid permeable porous membrane does not exceed the heavy liquid retention force.

JP 2008-6387 A JP 2019-130484 A

As described in Patent Document 1, conventional continuous liquid-liquid separators required auxiliary devices, such as an interface monitor and a flow rate adjuster, for adjusting the liquid feed amount and liquid feed speed conditions in order to keep the interface position between the separated upper and lower layers constant.
On the other hand, in the continuous liquid-liquid separator described in Patent Document 2, a porous membrane that allows only one of the heavy liquid and the light liquid to pass through and does not allow the other to pass through is used to separate the heavy liquid and the light liquid, so that no additional device is required to monitor the interface or adjust the flow rate. However, since Patent Document 2 utilizes the selectivity of the permeability and non-permeability of the porous membrane for different liquid types, it is necessary to adjust the material and pore size of the porous membrane according to the wettability of each of the heavy liquid and the light liquid, and it is poor in versatility.

The present invention was made in consideration of the current situation, and aims to provide a continuous liquid-liquid separator that can perform phase separation of various solution systems with a simple configuration, without requiring additional devices to monitor the interface or adjust the flow rate.

The inventors have conducted intensive research to solve the above problems, and have found that the above problems can be solved by providing an interface adjustment mechanism that fixes the height of the interface between the two phases in a chamber into which a two-phase liquid that separates into two phases, a light liquid and a heavy liquid, which are not completely miscible with each other, flows continuously, and by making the heights of the interface, the light liquid outlet, and the heavy liquid outlet the same.

In order to solve the above problems, the present invention employs the following means based on the above findings.
(1) A continuous liquid-liquid separator having a structure in which a two-phase liquid consisting of at least two or more components that are not completely miscible with each other and separate into two phases, a light liquid and a heavy liquid, is introduced through an inlet provided on one side of a chamber, and the light liquid and the heavy liquid are discharged through a light liquid outlet and a heavy liquid outlet provided on the other side, respectively, and is provided with an interface adjustment mechanism between the inlet and both outlets for adjusting the interface between the light liquid and the heavy liquid, and the interface adjustment mechanism comprises two mesh plates whose upper and lower distance gradually decreases from the upstream side to the downstream side and which separate the two-phase liquid into upper and lower layers, and an upper and lower layer separator adjacent to the downstream ends of the two mesh plates and which forms a Y-shaped cross section together with the two mesh plates, and the height of the interface between the upper and lower layers fixed by the upper and lower layer separator is the same as the height of the light liquid outlet and the heavy liquid outlet.
(2) The continuous liquid-liquid separation device according to (1) above, wherein the two mesh plates have minute gaps at their ends on both the outlet ports side for removing air bubbles.
(3) A method for continuously separating a two-phase liquid consisting of at least two or more types of components that are not completely miscible with each other and separate into two phases, a light liquid and a heavy liquid, comprising the steps of: continuously introducing the two-phase liquid into a chamber having an inlet on one side and a light liquid outlet and a heavy liquid outlet of the same height on the other side; separating the two-phase liquid into upper and lower layers using two mesh plates that are installed between the inlet and both outlets with the vertical distance therebetween gradually decreasing from the upstream side to the downstream side, suppressing the permeation of the heavy liquid and allowing the floating light liquid to permeate; forming a Y-shaped cross section together with the two mesh plates and fixing the interface between the upper and lower layers using upper and lower layer separators that are the same height as the both outlets; and discharging the light liquid and the heavy liquid from the light liquid outlet and the heavy liquid outlet, respectively.

The present invention provides a highly versatile continuous liquid-liquid separator and a continuous liquid-liquid separation method that can perform phase separation of various solution systems without requiring any additional devices for monitoring or adjusting the interface.

FIG. 1 is a side view showing a schematic overview of a continuous liquid-liquid separator according to the present invention. A diagram illustrating a conventional settler in which the light liquid outlet and the heavy liquid outlet are provided at different heights. An explanatory diagram of the same settler when the heights of both outlets are the same but the heights of the interfaces are different An explanatory diagram of the settler when the height of both outlets and the interface are the same Schematic diagram of capillary force when the heavy liquid is an aqueous phase, the mesh plate is hydrophilic, and there is no pressure applied from the aqueous phase to the mesh plate. Schematic diagram of capillary force when the heavy liquid is an aqueous phase, the mesh plate is hydrophilic, and there is pressure from the aqueous phase to the mesh plate. Photographs showing the liquid transfer state when the amount of heavy liquid in the separator according to the present invention is greater (Example 1) and when the amount of light liquid is greater (Example 2)

The present invention relates to a continuous liquid-liquid separation device and method, which are capable of separating a two-phase liquid consisting of at least two or more components that are not completely miscible with each other and separate into two phases, a light liquid and a heavy liquid, into upper and lower layers with a certain interfacial height while flowing in a mixed state, and discharging each phase from a light liquid outlet and a heavy liquid outlet, which are at the same height as the interfacial height, and is characterized in that an interface adjustment mechanism consisting of two mesh plates and upper and lower layer separators is installed to fix the liquid-liquid interface separated into the upper and lower layers at the same height as both outlets.
An outline of a continuous liquid-liquid separator according to an embodiment of the present invention (hereinafter referred to as "this embodiment") is shown in FIG.
Each component of the present embodiment will be described in detail below, but these are for the purpose of explaining the present invention and do not limit the scope of the present invention.
In this specification, the use of "to" to indicate a range of values means that the values before and after it are included as the lower limit and upper limit.

<Light liquid outlet, heavy liquid outlet, and height of interface between light liquid and heavy liquid>
First, the need to make the height of the light liquid outlet and the heavy liquid outlet the same as the interface between the light liquid and the heavy liquid will be described.
As shown in Figure 2, in the case of a settler having a light liquid outlet and a heavy liquid outlet provided above and below, if there is a difference in the pressure that the two outlets receive from the liquid, the heavy liquid outlet of the lower phase will be preferentially discharged, so an interface monitoring device, a discharge control valve, etc. are required.
Furthermore, as shown in FIG. 3, if both outlets are at the same height, when the interface is lower than both outlets, the light liquid is preferentially discharged, and when the interface is higher than both outlets, the heavy liquid is preferentially discharged.
Therefore, if the height of both the light liquid outlet and the heavy liquid outlet and the height of the liquid-liquid interface are made the same as shown in Figure 4, the upper and lower phases will flow out in a balanced manner from the outlets. However, since the liquid-liquid interface is not always constant, it is necessary to fix the height of the liquid-liquid interface so that it is the same as the height of both outlets.

The present invention is characterized by the installation of an interface adjustment mechanism consisting of two mesh plates and an upper and lower layer separator to separate the two-phase liquid into upper and lower layers and fix the liquid-liquid interface at the same height as both outlets.

In reality, each outlet has a finite size in the vertical direction, so "same height" means, more precisely, that the lower end of the light liquid outlet and the upper end of the heavy liquid outlet are at the same height as the liquid-liquid interface fixed by the upper and lower layer separators.

<Mesh plate>
The two mesh plates in this embodiment have openings that have a force (capillary force) that fixes the heavy liquid to the mesh plates. The capillary force in the mesh plates, i.e., the wettability, needs to be controlled only for the heavy liquid.
The shape of the opening may be either square or round, but if it is square, it shall have an opening diameter converted into a circle of radius r.
The capillary pressure Pc of a heavy liquid at an opening of radius r is expressed by the following equation 1, so the capillary force depends on the opening diameter r.
(Equation 1)
Pc=2γcosθ/r
(γ: interfacial tension between heavy liquid and light liquid, θ: contact angle of heavy liquid)

Fig. 5 shows the capillary force when the heavy liquid is an aqueous phase, the material of the mesh plate is hydrophilic, and there is no pressure of the aqueous phase on the mesh plate, while Fig. 6 is a diagram explaining the capillary force when the heavy liquid is an aqueous phase, the material of the mesh plate is hydrophilic, and there is pressure of the aqueous phase on the mesh plate. If the mesh plate has affinity for the heavy liquid (aqueous phase), the heavy liquid (aqueous phase) will be fixed to the mesh plate by the capillary force of the openings in the mesh plate, regardless of whether there is pressure from the aqueous phase.
When the heavy liquid is an oil phase, a hydrophobic mesh plate can be used regardless of whether the light liquid is an oil phase or an aqueous phase.

The opening diameter of the mesh plate is preferably about 0.2 to 5.0 mm, and more preferably about 0.75 to 2.0 mm, allowing for the separation of two-phase solutions in various combinations.

In this embodiment, the material of the mesh plate is not particularly limited, but examples of hydrophilic materials include hydrophilized polytetrafluoroethylene, acrylic resin, polyamide, polyimide, polyester, polycarbonate, polyether, polyurethane, ceramics, metal, etc. In particular, polymethacrylate is preferable.
Examples of hydrophobic materials include polytetrafluoroethylene (PTFE), polyolefin, polystyrene, polyphenylene vinylene, and polyvinyl chloride.

These two mesh plates divide the flow path into three parts, upper, middle, and lower, on the upstream side of the chamber, but are arranged so that the spacing between the top and bottom gradually decreases toward the downstream side, so that the middle flow path gradually narrows, and on the downstream side, only the upper and lower flow paths remain.
When the amount of heavy liquid in the chamber of the two-phase liquid exceeds the height of the separator, the light liquid flows through the gaps at the upstream end of the mesh plates and is collected in the upper flow path, while the heavy liquid is collected in the lower flow path and the intermediate flow path. However, since the intermediate flow path gradually narrows, the two-phase liquid is separated into upper and lower layers of light liquid and heavy liquid at the downstream ends of the two mesh plates.
When the amount of heavy liquid in the chamber falls below the height of the separator, the light liquid flows through the upper flow path and the intermediate flow path, but the intermediate flow path gradually narrows, so that the light liquid and the heavy liquid are separated into two layers, upper and lower, at the downstream ends of the two mesh plates, as described above.

The two-phase liquid that can be used in the embodiments of the present invention is a two-phase liquid consisting of at least two components that are not completely miscible with each other and separate into two phases, a light liquid and a heavy liquid, and examples of such two-phase liquids include water/pentane, water/hexane, water/heptane, water/octane, water/nonane, water/decane, water/cyclohexane, water/decalin, water/benzene, water/toluene, water/xylene, water/nitrobenzene, water/aniline, water/phenol, water/methyl acetate, water/ethyl acetate, water/propyl acetate, water/butyl acetate, water/diene, etc. These include ethyl ether, water/dipropyl ether, water/dibutyl ether, water/diphenyl ether, water/butanol, water/hexanol, water/heptanol, water/octanol, water/nonanol, water/decanol, water/butoxyethanol, water/triethylamine, water/chloroform, water/carbon tetrachloride, Fluorinert/water, methanol/hexane, methanol/cyclohexane, N,N-dimethylformamide/hexane, and N-methyl-2-pyrrolidone/hexane.

Other examples include three- or more-component two-phase liquids in which inorganic salts or organic compounds are dissolved in the two-component two-phase liquid. Other examples include liquid mixtures such as water/acetone, water/formaldehyde, water/tetrahydrofuran, water/N,N'-dimethylformamide, water/dimethylsulfoxide, water/methanol, water/ethylene carbonate, and water/acetic acid in which inorganic salts or organic compounds are dissolved and the mixtures are separated into two phases, a light liquid and a heavy liquid.

<Upper and lower layer separator>
In this embodiment, the upper and lower layer separators are adjacent to the downstream ends of the two mesh plates and form a Y-shaped cross section together with the two mesh plates, and therefore have the effect of maintaining and fixing the interfacial height between the light liquid and the heavy liquid.
As mentioned earlier, by making the heights of the light liquid outlet and the heavy liquid outlet the same as the interface height between the light liquid and the heavy liquid, the light liquid and the heavy liquid can be discharged in a balanced manner from each outlet.

In addition, if air bubbles are entrapped in the inflowing liquid, clogging may occur, so there may be a small gap between the downstream ends of the two mesh plates and the upper and lower layer separators to allow air bubbles to escape.

Example 1
Using an acrylic monomer, a liquid-liquid separator as shown in FIG. 1 was produced using a stereolithography 3D printer (product name: form3 manufactured by formlabs).
This liquid-liquid separator has an interface adjustment section consisting of two upstream mesh plates and an upper and lower layer separator on the downstream side, within a 13 x 50 x 10 mm transparent chamber having an inlet, a light liquid outlet, and a heavy liquid outlet. The two mesh plates (13 x 15 x 0.5 mm, square opening mesh size 2 mm) have their upstream end located 20 mm away from the side of the chamber on the inlet side, and are installed so that the vertical distance between them gradually decreases symmetrically from 6 mm towards the downstream end, and the upper and lower layer separator (13 x 15 x 1 mm) is installed so as to connect the downstream ends of the two mesh plates to the side of the chamber on the outlet side, at the same height as the light liquid outlet and heavy liquid outlet.
The light liquid outlet and the heavy liquid outlet had an inner diameter of 2 mm and a length of 5 cm.
A two-phase liquid of cyclohexane (light liquid) and water colored with food coloring (heavy liquid) was fed from the inlet of the liquid-liquid separator at a flow rate of light liquid: 1.0 mL/min and heavy liquid: 0.5 mL/min for 30 minutes.
Only cyclohexane was discharged from the light liquid outlet, and only water colored with food coloring was discharged from the heavy liquid outlet.

Example 2
A two-phase liquid of cyclohexane (light liquid) and water colored with food coloring (heavy liquid) was pumped for 30 minutes at a flow rate of 1.0 mL/min for the light liquid and 0.5 mL/min for the heavy liquid. Only cyclohexane was discharged from the light liquid outlet and only water colored with food coloring from the heavy liquid outlet.

Example 3
Except for changing the mesh size of the rectangular openings of the two mesh plates to 1 mm, the same liquid-liquid separator as in Example 1 was used and liquid was pumped under the same conditions as in Example 1. Only cyclohexane was discharged from the light liquid outlet and water colored with food coloring was discharged from the heavy liquid outlet.

Example 4
Except for changing the flow rates of the two-phase liquid to light liquid: 1 mL/min and heavy liquid: 1 mL/min, the liquids were sent in the same manner as in Example 1. Only cyclohexane was discharged from the light liquid outlet, and only water colored with food coloring was discharged from the heavy liquid outlet.

Example 5
Except for changing the flow rates of the two-phase liquid to light liquid: 4 mL/min and heavy liquid: 4 mL/min, the liquid was pumped in the same manner as in Example 1. Only cyclohexane was discharged from the light liquid outlet, and only water colored with food coloring was discharged from the heavy liquid outlet.

Example 6
The liquid was sent in the same manner as in Example 1, except that the light liquid was a mixed solution of 80 vol% 1-butanol/20 vol% water, the heavy liquid was a mixed solution of 90 vol% water/10 vol% 1-butanol, the inner diameter of the light liquid outlet and the heavy liquid outlet were 1 mm, the length was 45 cm, and the flow rate of the two-phase liquid was light liquid: 1 mL/min, heavy liquid: 1 mL/min. The light liquid was discharged from the light liquid outlet, and the heavy liquid was discharged from the heavy liquid outlet.

(Example 7)
Using polyamide powder, a liquid-liquid separator of the same size as in Example 1 was produced using a laser sintering 3D printer (product name: LISA-PRO manufactured by Sinterit) with the exception that the inner diameter of the light liquid outlet and the heavy liquid outlet were 1 mm and the mesh size of the openings was 1 mm. The light liquid was changed to ethyl acetate, the heavy liquid to water, and the flow rate of the two-phase liquid was changed to light liquid: 1 mL/min and heavy liquid: 1 mL/min, and the liquid was sent in the same manner as in Example 1. Light liquid was discharged from the light liquid outlet, and heavy liquid was discharged from the heavy liquid outlet.

(Example 8)
Using polyamide powder, a liquid-liquid separator of the same size as in Example 1 was produced using the same 3D printer as in Example 7, except that the inner diameter of the pipe of the heavy liquid outlet was 1 mm, the length was 45 cm, and the mesh size of the opening was 1 mm. The light liquid was a mixed solution of 10 vol% methanol/90 vol% n-hexane, and the heavy liquid was a mixed solution of 40 vol% methanol/60 vol% n-hexane, and the flow rate of the two-phase liquid was changed to light liquid: 1 mL/min and heavy liquid: 1 mL/min. The liquid was delivered in the same manner as in Example 1. Light liquid was discharged from the light liquid outlet, and heavy liquid was discharged from the heavy liquid outlet.

(Example 9)
Using polyamide powder, a liquid-liquid separator of the same size as in Example 1 was produced using the same 3D printer as in Example 7, except that the inner diameter of the light liquid outlet and the heavy liquid outlet were changed to 1 mm and the mesh size of the opening was changed to 1 mm. The light liquid was a mixed solution of 5 vol% N,N-dimethylformamide/95 vol% n-hexane, and the heavy liquid was a mixed solution of 90 vol% N,N-dimethylformamide/10 vol% hexane, and the liquid was delivered in the same manner as in Example 1. Light liquid was discharged from the light liquid outlet, and heavy liquid was discharged from the heavy liquid outlet.

The configurations of the liquid-liquid separators and the liquid sending conditions of the above Examples 1 to 9 are summarized in Table 1 below.
The results of Examples 1 and 2 are shown in the photograph of FIG.

The heavy liquid is shown in dark grey in Figure 7. In both cases, Example 1 (left diagram), where the amount of heavy liquid in the chamber is greater, and Example 2 (right diagram), where the amount of light liquid in the chamber is greater, the light liquid is discharged from the light liquid outlet, and only the heavy liquid is discharged from the heavy liquid outlet, and it was found that the interface between the upper and lower layers is always maintained at a constant height.
Therefore, from Examples 1 and 2, it was found that even if the liquid amounts of the light liquid and the heavy liquid are not balanced, the interface between the upper and lower layers is always maintained at a constant height, and the light liquid outlet and the heavy liquid outlet are at the same height, so that precise liquid-liquid separation can be performed automatically.

From Examples 3 to 5, it was found that the effect of the present invention can be sufficiently obtained even when the opening size of the mesh plate and the flow rate of the two-phase liquid are within a certain range.
From Examples 6 to 9, it was found that continuous phase separation could be effectively achieved even if the material of the mesh plate or the combination of the two-phase liquid was changed.
In addition, in Examples 2 and 8, the inner diameters of the pipes of the light liquid outlet and the heavy liquid outlet are not balanced, and a load is applied by either the light liquid or the heavy liquid after discharge. However, it was found that with a difference in the inner diameters of the pipes of this magnitude, phase-separated liquid can be obtained from each outlet without any shift in the interfacial height.
From the above, it has been demonstrated that the present invention does not require strict size setting or liquid transfer conditions, and can be widely used for liquid-liquid separation of various two-phase liquids.

According to the present invention, a continuous liquid-liquid separator with a simple configuration is used to perform phase separation of various solution systems, and therefore the separator can be used in continuous precision production processes for a variety of chemical products.

Claims (3)

A continuous liquid-liquid separator having a structure in which a two-phase liquid consisting of at least two or more kinds of components which are not completely miscible with each other and separate into two phases, a light liquid and a heavy liquid, is introduced from an inlet provided on one side of a chamber, and the light liquid and the heavy liquid are discharged from a light liquid outlet and a heavy liquid outlet provided on the other side, respectively,
an interface adjustment mechanism for adjusting an interface between the light liquid and the heavy liquid between the inlet and both the outlets;
The interface adjustment mechanism includes:
Two mesh plates whose upper and lower distances gradually decrease from the upstream side to the downstream side, separating the two-phase liquid into upper and lower layers; and
an upper and lower separator adjacent to the downstream ends of the two mesh plates and forming a Y-shaped cross section together with the two mesh plates;
A continuous liquid-liquid separator, wherein the height of the interface between the upper and lower layers fixed by the upper and lower layer separators is the same as the heights of the light liquid outlet and the heavy liquid outlet. The continuous liquid-liquid separation device according to claim 1, wherein there is a minute gap between the downstream ends of the two mesh plates and the upper and lower layer separators to allow air bubbles to escape. A method for continuously separating a two-phase liquid consisting of at least two or more components that are completely immiscible with each other and separate into two phases, a light liquid and a heavy liquid, comprising the steps of:
The two-phase liquid is continuously introduced into a chamber having an inlet on one side and a light liquid outlet and a heavy liquid outlet at the same height on the other side;
Between the inlet and both of the outlets, two mesh plates are installed with a vertical distance gradually decreasing from the upstream side to the downstream side, suppressing the permeation of the heavy liquid and allowing the floating light liquid to permeate, thereby separating the two-phase liquid into upper and lower layers,
The mesh plates are joined together to form a Y-shaped cross section, and the interface between the upper and lower layers is fixed by an upper and lower layer separator having the same height as both of the exhaust ports;
A continuous liquid-liquid separation method, comprising discharging a light liquid and a heavy liquid from the light liquid discharge outlet and the heavy liquid discharge outlet, respectively.