JPH04298221A - Membrane separator - Google Patents

Abstract

PURPOSE:To provide the device for improving the accuracy of separated products. CONSTITUTION:A mechanical booster pump 12 and a cold trap 6 are disposed between the unit disposed in the final stage of the device connected with plural pieces of the membrane units 1 in multiple stages in series and a vacuum pump 7 connected thereto. Then, the separation is effectively executed. The energy to be consumed by the cold trap 6 is decreased. Since the mechanical booster pump 12 is used in the final stage, this device is advantageous in terms of cost.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a membrane separation device, more preferably a membrane separation device, in which a mixed liquid is stored in one of the separation membranes with a separation membrane as a boundary, and the other side is depressurized using a vacuum pump. This invention relates to a membrane separation device that allows liquid to permeate and evaporate using a pressure difference.

0002

2. Description of the Related Art Pervaporation is known to be suitable for the fractional separation of azeotropic mixtures, that is, isomers of organic solvents with similar boiling points, which cannot be separated by ordinary distillation methods. For this pervaporation, for example, a vinyl alcohol polymer membrane, an acrylonitrile polymer membrane, or a composite membrane consisting of ethyl cellulose and polyethylene or cellulose butyl acetate is used as a separation membrane,
An organic liquid mixture is stored in one side of the separation membrane, and the other separation side is depressurized using a vacuum pump, and the pressure difference causes the liquid to permeate and be evaporated and separated.

However, in such pervaporation, the temperature decreases due to the latent heat of vaporization of the liquid, and there is a risk that the liquid may freeze, resulting in a situation where the liquid cannot be separated. Based on this liquid separation behavior, it has been proposed to divide the membrane module unit into multiple units, connect the multiple membrane modules in series, and heat the mixed liquid before introducing it into each membrane module. (
For example, Japanese Patent Publication No. 58-95523).

By the way, in this pervaporation, it is effective to maintain a high degree of vacuum inside the membrane module unit, and it is also necessary to collect the permeated vapor that has passed through the separation membrane and evaporated. Steam is introduced into a cold trap under reduced pressure and condensed, but in this case a large amount of energy is required to keep the cold trap at a low temperature.

[0005] As a means of solving such problems, it has been proposed to provide a mechanical booster pump between the membrane module and the vacuum pump (for example, Japanese Patent Laid-Open No. 6
3-93303).

[0006]

By the way, in a membrane separation apparatus in which a plurality of membrane module units as described above are arranged in series in multiple stages, it is not economical to arrange a mechanical booster pump as described above in each membrane module. Not only is there a problem with this, but there is also the problem that it cannot necessarily be effective in terms of performance.

[0007]

[Means for Solving the Problems] The present invention has been made in order to solve the above-mentioned problems of the conventional art. In a method for separating mixed liquids by pervaporation, which heats the liquid before introducing it into the unit, a mechanical booster pump is installed between the membrane module unit located at the final stage and the vacuum pump, and this mechanical booster A membrane separation device is provided in which a cold trap is placed between a pump and a vacuum pump.

[0008]

[Function] In the membrane separation apparatus of the present invention, a large amount of liquid to be separated is separated in a relatively low degree of vacuum in the membrane module unit at the front stage, and a mechanical booster pump is used in the membrane module unit at the final stage. The mixed liquid is fractionated and separated under a high degree of vacuum using a vacuum pump.

[0009]

[Embodiment] An embodiment of the membrane separation apparatus according to the present invention will be described below with reference to the drawings. In the figure 1, 2,
3 are membrane module units, and the membrane module units 1 to 3 are connected in series. In detail,
A mixed liquid L to be separated is sent to the first stage membrane module unit 1 from a line P1 by a pump 4, and a heater 5
It is supplied to the primary side 1a thereof. And the secondary side 1 of this first stage membrane module unit 1
b is connected to a vacuum pump 7 via a cold trap 6, where the mixed liquid L is primarily separated and necessary concentration is performed. This primary separated mixed liquid L is line P2
is heated by a second heater 8 and introduced into the second stage membrane module unit 2, where it is brought into contact with a cold trap 10 by a vacuum pump 9 to create a high vacuum state from the inside of the first stage membrane module unit 1. It is fractionated and separated to further increase its concentration.

Furthermore, the mixed liquid L whose concentration has been increased in the second stage membrane module unit 2 passes through a line P3 and is heated by a heater 11, and then heated by the third stage membrane module unit 3 (in this embodiment, It is introduced into the final stage (membrane module unit). This third membrane module unit 3
On the secondary side 3b, a booster pump 12, a cold trap 13, and a vacuum pump 14 are connected in series, and the degree of vacuum is higher than that of the second stage membrane module unit 2, where the mixed liquid L is finally The waste is separated into two parts. The liquid thus concentrated is the product F on line P4.
It is extracted through. In addition, line P5
are provided to guide the heating medium S to each of the heaters 5, 8, and 11.

Next, Table 1 shows the results of experiments conducted by the present inventor.

0012

Effects of the Invention As is clear from the above description, according to the membrane separation apparatus of the present invention, a plurality of membrane module units are connected in series in multiple stages, and in the final stage membrane module unit, the membrane module unit and the vacuum By placing a booster pump between the pumps, we were able to achieve the following effects. (1) Since the degree of vacuum in the membrane module unit at the final stage can be easily increased, division and separation can be carried out effectively, and as a result, the precision of the product can be improved. (2) The energy in the cold trap can be reduced. (3) When a booster pump is provided in the membrane module unit at the front stage, a large capacity booster pump is required because there is a large amount of liquid to be separated, which results in a significant increase in cost. The problem will disappear.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a membrane separation device according to the present invention.

[Explanation of symbols]

1, 2, 3 Membrane module unit 4...
Pump 5, 8, 11 Heater
6, 10, 13 Cold trap 7, 9, 14...Vacuum pump 12 Booster pump.

Claims (1)

[Claims] [Claim 1] A mixed liquid separation device using a pervaporation method, in which a plurality of membrane module units are connected in series in multiple stages and the mixed liquid is heated before being introduced into each module unit. A membrane separation device in which a mechanical booster pump is provided between the membrane module unit located in the 100-degree membrane module unit and the vacuum pump, and a cold trap is placed between the mechanical booster pump and the vacuum pump.