JPH06246137A - Separator for mixed liquid - Google Patents

Abstract

PURPOSE:To improve the efficiency of a heat exchanger and to miniaturize equipment when condensing and liquefying permeated gas permeating though a separation membrane module by using the heat exchanger by installing a circulating line for dispersing a part of the condensed and liquefied components over the heat transfer surface of the heat transfer in a liquid state. CONSTITUTION:A separation membrane module 1 is evacuated on the secondary side through a line and a heat exchanger 5 by a line 10 connected to a vacuum pump. Components permeable through a membrane 1a permeate though the membrane 1a by a difference in vapor pressure between the primary and secondary sides of the membrane 1a to attain the heat exchanger 5 through the line 4. Since the heat transfer surface of the heat exchanger 5 is wetted by the condensation and liquefaction of the permeated components dispersed through a circulating line 8, the permeated vapor fed from the line 4 is effectively condensed. The permeated components condensed by the heat exchanger 5 are temporarily accumulated in a condensate tank 6 and a part of the condensate is circulated to the heat exchanger 5 through the circulating line 8 by a pump 7 to intermittently or continuously discharge all or part of that part from a line 9 to outside the system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus and method for separating mixed liquids by pervaporation or vapor permeation.
More specifically, the present invention relates to a mixed liquid separation device in which the heat transfer area of a heat exchanger for condensing a gas that has permeated by the pervaporation method or the vapor permeation method is reduced to reduce the device space and the device cost.

[0002]

2. Description of the Related Art A device for separating a mixed liquid by a pervaporation method or a vapor permeation method is widely known. The pervaporation method uses a membrane that has a special affinity with certain components of the mixed liquid, and puts the mixed liquid on one side (primary side) of the membrane and depressurizes the other side (secondary side) with a vacuum pump. , Or a separation method of separating a specific component by purging with an inert gas and maintaining the vapor partial pressure of the permeating component on the secondary side at a value smaller than the equilibrium vapor pressure on the primary side. This is a method in which the mixed liquid is heated and previously supplied as vapor to the primary side of the membrane, and similarly separated. In these methods, the permeation component permeates the membrane in a gas state, and therefore needs to be condensed and liquefied.

[0003]

Generally, for condensing liquefaction, a heat exchanger that transfers heat through a heat transfer surface is used, but the required heat transfer area is large and it is difficult to save space.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above problems, and as a result, a part of the condensed liquid is circulated and sprayed on the heat transfer surface, so that the heat transfer efficiency can be improved. Found that the heat transfer area can be reduced as
The present invention has been reached. That is, the gist of the present invention is to supply a mixed liquid to a separation membrane module, selectively permeate the membrane as a gas with a specific component by a permeation method or a vapor permeation method in the separation membrane module, and pass the permeated gas by a heat exchanger. In a separation device for a mixed liquid to be condensed and liquefied, a separation device for a mixed liquid, characterized in that a circulation line for spraying a part of the condensed and liquefied permeated component in a liquid state on the heat transfer surface of the heat exchanger is provided. An apparatus is characterized in that the flow rate of the permeating component liquid to be circulated and dispersed when the separation is performed is 1 to 50 liter / min per unit area (1 m ² ) of the heat transfer surface of the heat exchanger.

[0005]

According to the present invention, the gas passing through the separation membrane is condensed and liquefied by a heat exchanger that transfers heat through the heat transfer surface, and a part of the condensed liquid is circulated and sprayed in a liquid state on the heat transfer surface. As a result, the heat transfer surface is wetted by the liquid of the permeation component, and heat transfer is performed in a thin film, so that the overall heat transfer coefficient of the heat exchanger is increased. as a result,
The heat transfer area required for condensing the permeated gas can be reduced, and the size of the entire separation device can be reduced.

Hereinafter, description will be made based on the specific example shown in FIG. FIG. 1 is a schematic view showing an example of the device of the present invention. In the figure, 1 is a separation membrane module, 5 is a heat exchanger, and 7 is a circulation pump. The mixed liquid to be separated is not limited as long as it is a mixed liquid that can be separated by the pervaporation method or the vapor permeation method, but in this example, an alcohol-water mixed liquid, more specifically, isopropyl alcohol (I
Separation of (abbreviated as PA) -water mixed liquid is typical.

The separation membrane module 1 may have any shape as long as it is a module used in the pervaporation method or the vapor permeation method, and may have a flat membrane shape, a spiral membrane shape, a hollow fiber membrane shape or the like. The hollow fiber membrane bundle module is suitable because it has a wide membrane area and can withstand the pressure difference between the primary side (raw material liquid side) and the secondary side (permeate side). A raw material liquid to be separated is supplied from a line 2 to the primary side of the separation membrane module 1. The non-permeable fluid that does not permeate the selectively permeable membrane 1a flows to the line 3.

The secondary side of the separation membrane module 1 is line 4,
The pressure is reduced from the line 10 via the heat exchanger 5. The component that permeates the selectively permeable membrane 1a permeates the membrane 1a due to the difference in vapor pressure between the primary side and the secondary side of the membrane and reaches the heat exchanger 5 through the line 4. The surface of the heat transfer surface of the heat exchanger 5 is wet with the condensate of the permeation component dispersed through the line 8, and the permeated vapor supplied from the line 4 is efficiently condensed. The tip of the line 8 is preferably a disperser that disperses the condensate throughout the heat exchanger 5.

The permeated component condensed by the heat exchanger 5 is temporarily stored in the condensate tank 6, and a part of the condensate is circulated to the heat exchanger 5 through the line 8 by the pump 7 and intermittently or continuously. The whole amount or a part of it is extracted from the system 9.
The line 10 is connected to a vacuum pump (not shown) so that the secondary side of the membrane and thereafter are in a reduced pressure state. It is preferable that the end of the line 10 on the condensation tank 6 side is opened downward or sideways so that the condensate does not enter the line 10.

Although the circulating liquid tank 6 is not shown, it is preferable that the outside has a double jacket structure and the outside of the condensate tank 6 is cooled by a refrigerant. This is because the inside of the condensate tank 6 is depressurized from the line 10, and the condensate is vaporized again when the temperature rises. The flow rate of the condensate circulated from the line 8 to the heat exchanger 5 is 1 to 50 liter / min per 1 m ^{2 of the} heat transfer surface, preferably 5
~ 20 liters / min. If it is less than this, the effect of circulating the condensate is small, and if it is larger, the efficiency of the heat exchanger 5 is hardly improved and the load of the pump 7 is increased, which is not preferable.

[0011]

EXAMPLES Examples will be shown below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 and Comparative Example 1 An example in which IPA-water system is taken as an example of a mixed liquid and water is selectively permeated and separated by a hydrophilic hollow fiber membrane module using the apparatus schematically shown in FIG. Will be specifically described by showing numerical values. Line 8 of FIG. 1 of Example 1
This is an example in which the condensate is circulated and sprayed according to Comparative Example 1
Shows an example in which the condensate was not circulated or sprayed through the line 8. Table 1 shows the operating conditions.

[0012]

[Table 1]

[0013]

According to the separation apparatus of the present invention, the condenser can be downsized, and the separation apparatus as a whole can be made compact.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus of the present invention.

[Explanation of symbols]

 1 Separation Membrane Module 1a Selective Permeation Membrane 2 Raw Fluid 3 Non-Permeation Fluid 4 Permeation Fluid 5 Heat Exchanger 6 Condensate Tank 7 Circulation Pump 8 Spray Liquid Circulation Line 9 Permeate Extraction 10 Decompression Line

Claims (2)

[Claims] 1. A mixed liquid is supplied to a separation membrane module,
In the separation membrane module, where a specific component is selectively permeated as a gas by permeation vaporization or vapor permeation in a separation membrane module, and the permeated gas is condensed and liquefied by a heat exchanger A separating device for a mixed liquid, wherein a circulation line for spraying the liquid in a liquid state is provided on the heat transfer surface of the heat exchanger. 2. The separation apparatus according to claim 1, wherein the flow rate of the permeating component liquid to be circulated and scattered is 1 to 50 liters / min per unit area (1 m ² ) of the heat transfer surface of the heat exchanger. .