JPS61125406A - Method and apparatus for separating liquid mixture - Google Patents

Abstract

PURPOSE:To reduce the flow resistance of a gas by condensing forcibly the vapor in a vapor chamber to reduce the partial pressure of the vapor, increasing the vaporization velocity on the surface of a separation membrane, and decreasing the flow rate of the gas in a discharge pipeline in the pervaporation method. CONSTITUTION:A liq. chamber 2 and a vapor chamber 3 are separated by a separation membrane 1, and the cooling surface 4 of a shell and tube heat exchanger, etc. is provided in the vapor chamber 3. A liq. mixture to be treated is supplied into the liq. chamber 2 from a liq. supply port 7, and the pressure in the vapor chamber 3 is reduced by a vacuum pump 6. A liq. component which is vaporized after permeating through the separation membrane 1 from the liq. chamber 2 is brought into contact with the cooling surface 4, and a part of the whole of the vapor is condensed. Consequently, the partial pressure of the vapor in the vapor chamber is reduced, the amt. of gas to be discharged from a gas discharge port 10 is reduced, and hence the flow resistance of the gas in a discharge pipe-line connected to the gas discharge port 10 is decreased.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to the production of mixtures of two or more organic liquids, mixtures of water and organic liquids, solutions of organic compounds, etc. (hereinafter referred to as these) by a pervaporation method. (collectively called liquid mixture)
This invention relates to a novel method and apparatus for separating specific liquid components from.

[Prior art] In the pervaporation method, one chamber separated by a separation membrane is used as a liquid chamber and the other chamber as a vaporized gas chamber, and a liquid mixture is supplied to the liquid chamber and the pressure in the vaporized gas chamber is reduced. Therefore, this is a method in which liquid components passing through a separation membrane are separated by vaporizing them from the membrane surface. As a device used in the above method, the device shown in FIG. 2 is generally known. In FIG. 2, the device has a liquid chamber 2 and a vaporized gas chamber 3, which are separated by a separation B1, and a condenser 12 and a gas-liquid separator 5 are used as means for reducing the pressure in the vaporized gas chamber 3. It has a pressure reducing pump 6. In a method using such an apparatus, the liquid component in the liquid mixture that has passed through the separation Ht from the liquid chamber 2 is vaporized in the vaporization gas chamber 3, and then condensed in the condenser 12 to form a gas-liquid component l1.
1115. Further, a liquid mixture is supplied to the liquid chamber 2 from a liquid supply lower and taken out from a liquid discharge port 8.

[Problems to be Solved by the Invention] However, when attempting to implement the pervaporation method using the above-mentioned apparatus, the following problems arise. That is, since the liquid component is vaporized in the vaporized gas chamber 3, when the chamber is pulled by the vacuum pump 6, a considerable amount of gas flows through the pipe between the vaporized gas chamber 3 and the condenser 12. Therefore, due to the flow resistance of the piping, the vaporized gas chamber 3 cannot be sufficiently depressurized, and the vaporization on the surface of the separation membrane 1 facing the chamber is controlled, which not only reduces the permeate rate of the liquid component but also reduces the pressure of the specific liquid component. There is also a problem that the separation effect of

To solve this problem, we increased the flow path area of the piping section,
A method of reducing the flow resistance may be considered, but it not only has the drawback that the thickness of the flow path in the vaporized gas chamber increases, resulting in a decrease in the membrane area per unit volume of the separation device, but it also has the disadvantage of reducing the flow resistance until the predetermined operating vacuum level is reached. This method also has the disadvantage of increasing the evacuation time, which is disadvantageous in industrial implementation.

[Means for Solving the Problems] The present invention has been made in view of the above problems, and includes forcibly condensing part or all of the vaporized gas vaporized from the surface of the separation membrane in the vaporized gas chamber. This lowers the partial pressure of the vaporized gas in the vaporized gas chamber, increases the amount of vaporized gas from the separation membrane surface, and lowers the gas flow rate in the piping connected to the vaporized gas chamber to reduce the gas flow resistance. The present invention provides a method and device for separating mixed liquids that solves the above problems.

In the present invention, when a liquid mixture is supplied to a liquid chamber of a separation device having a liquid chamber and a vaporization gas chamber through a separation membrane, and the liquid component that passes through the separation membrane is vaporized and recovered in the vaporization gas chamber,
This is a method for separating a liquid mixture, characterized in that at least part of the vaporized gas is condensed in a vaporized gas chamber.

In the present invention, increasing the amount of vaporized gas to be condensed in the vaporizing gas chamber as much as possible reduces the partial pressure of the vaporized gas in the vaporizing gas chamber and increases the vaporization rate of the liquid component on the surface of the separation membrane. At the same time, it is preferable to reduce the amount of vaporized gas taken out from the vaporized gas chamber, lower the flow resistance in the piping, and further improve the separation characteristics in pervaporation. Therefore, the vaporized gas condenser in the vaporized gas chamber is , generally 20% of the vaporized gas generated on the surface of the separation membrane.
% or more, preferably 30% or more,
The method of condensing the vaporized gas in the vaporized gas chamber is not particularly limited, and the known methods for condensing the condensable gas are not limited. Examples include a method in which a cooling surface is provided inside the chamber, and a method in which a liquid or gas inert to the vaporized gas is blown into the vaporized gas chamber as a refrigerant.

In the method of the present invention, other conditions may be those known in the pervaporation method without particular limitation.For example, the liquid mixture supplied to the liquid chamber may be heated in advance, or a heating means may be provided in the chamber. It is preferable to heat the mixture in a range from .degree. C. to below the boiling point of the liquid mixture, and it is also desirable to reduce the pressure in the vaporizing gas chamber.Especially in this case, the effects of the present invention described below are significant. The above reduced pressure is 3
It is preferable to carry out the treatment in a range of 00+mHg or less, preferably 200s+wHg or less.

The invention also provides an apparatus for implementing the method described above. 1 and 3 are schematic diagrams showing representative embodiments of a separation apparatus for carrying out the method of the present invention.

The separation apparatus of the present invention is characterized in that it has a liquid chamber 2 and a vaporized gas chamber 3 with a separation membrane 1 in between, and that the vaporized gas chamber 3 has a cooling surface 4 therein.

In the present invention, as the separation membrane 1, any membrane conventionally used in pervaporation methods can be used without particular limitation.

W4 For example, cation exchange membranes, anion exchange membranes, cellulose polymer membranes, monopolymers such as polyethylene, polypropylene polyacrylonitrile, polyvinyl alcohol, polyvinyl acetal, polystyrene, polyester, polyamide, polytetrafluoroethylene, etc. Commonly used. Liquid enrichment 2 separated by the separation membrane 1
is a chamber in which a liquid mixture to be treated exists, and has a liquid supply lower for supplying the mixture and a discharge port 8 for discharging the treated liquid. Further, the vaporized gas chamber 3 has a gas vent port 10.
and is connected to the vacuum pump 6 as necessary.

The cooling surface 4 may be of any type as long as it has the ability to condense at least a portion of the gas vaporized from the separation membrane 1 surface in the vaporization gas chamber 3 by contacting the gas, and is used in a conventional condenser. The structure of the heat exchanger can be used without any particular restrictions. Generally, heat exchangers such as a shell-and-tube heat exchanger, a coil heat exchanger, a flat plate heat exchanger, and a jacket girder heat exchanger are used. The cooling surface 4 does not need to be present in the entire vaporized gas chamber 3, and depending on its cooling capacity, it condenses 20% or more, preferably 30% or more of the gas vaporized on the surface of the separation membrane 1 as described above. It is sufficient to make it exist in a size that makes it possible to do so.

In the device of the present invention, the vaporizing gas chamber 3 reduces the pressure inside the chamber,
In order to improve the vaporization speed of the vaporized gas, it is preferable to connect it to the vacuum pump 6. Such a connection may be made directly, but in order to prevent condensate mist or vaporized gas from leaking to the vacuum pump 6. , a gas-liquid portion M%5 having a liquid outlet 9 at the bottom as shown in FIG. 1 is provided between the vaporization gas chamber and the decompression pump 6, or a condenser 12 and Providing the gas-liquid separator 5 is a preferred embodiment. Further, the liquid condensed in the vaporized gas chamber 3 may be taken out together with the gas by the decompression pump 6, or an extraction port 11 for drawing out the liquid may be separately provided as shown in FIGS. 1 and 3. .

[Operation] According to the method of the present invention, part or almost all of the liquid component that has passed through the separation membrane 1 from the utility room 2 in the vaporization gas chamber 3 and has been vaporized is condensed. As a result, the partial pressure of the vaporized gas in the vaporized gas decreases, and the gas outlet 10
The amount of gas extracted from the gas outlet is reduced, and in some cases becomes almost zero, and the influence of piping resistance due to an increase in gas flow rate in the extraction piping connected to the gas extraction port 10 can be effectively prevented.

[Effects] Due to the above-mentioned action, even when performing the pervaporation method by reducing the pressure in the vaporization gas chamber, the pressure inside the vaporization gas chamber 3 can be highly reduced by the pressure reduction pump 6, and therefore a high permeation rate and a high permeation rate can be achieved. It is possible to process liquid mixtures with high separation efficiency. For example, mixing water heated to a liquid temperature of 50°C and isopropyl alcohol (hereinafter referred to as IPA! (Water/[PA)%/l] , ratio=20/
80) is supplied at an amount of 10'ζλ/min to a liquid chamber partitioned by a cation exchange membrane with a membrane area of 1.0 m, and when the pervaporation method is performed while taking out the overflow liquid, the third method according to the present invention In the case where 70% of the vaporized gas generated is routed through the cooling surface 4 using the device shown in the figure, and the remainder is condensed in the condenser 12, and in the case where the conventional device shown in FIG. In case of condensation, reduce pressure pump 6
When compared with the same capacity, the device of the present invention can reduce the vacancy inside the vaporized gas chamber 3 by more than 50% compared to the conventional device, and as a result, the permeation rate can be reduced by more than 80%, resulting in a separation efficiency of 50%. We were able to improve this by more than %.

[Brief explanation of drawings]

1 and 3 are schematic diagrams showing typical aspects of the separation device of the present invention, and FIG. 2 is a schematic diagram of a conventional separation device.
In the figure, 1 is a separation membrane, 2 is a liquid chamber, 3 is a vaporization gas chamber,
4 is a cooling surface, 5 is a gas-liquid separation, 6 is a pressure reduction pump, 7 is a liquid supply port, 8 is a liquid discharge port, 9 is a liquid outlet, 10 is a gas discharge port,
Reference numeral 11 indicates an outlet, and 12 indicates a condenser.

Claims (4)

[Claims] (1) When a liquid mixture is supplied to the liquid chamber of a separation device having a liquid chamber and a vaporized gas chamber through a separation membrane, and the liquid component that permeates through the separation membrane is vaporized and recovered in the vaporized gas chamber, the vaporized gas A method for separating a liquid mixture, characterized in that at least a portion of the liquid mixture is condensed in a vaporizing gas chamber. (2) The method according to claim 1, which is carried out by reducing the pressure in the vaporizing gas chamber. (3) The method according to claim 1, wherein 20% or more of the vaporized gas is condensed in the vaporized gas chamber. (4) A separation device for a liquid mixture, comprising a liquid chamber and a vaporized gas chamber via a separation membrane, and the vaporized gas chamber has a cooling surface inside.