JPH04298222A - Membrane separation of liquid mixture - Google Patents

Abstract

PURPOSE:To improve the sepn. performance of a liquid mixture and to reduce an initial cost by using membrane module units of an internal heating type and external heating type respectively having the blocks partitioned by pervaporation membranes. CONSTITUTION:The liquid mixture F is introduced into the one block partitioned by the pervaporation membrane 3 of the membrane module 1 of the internal heating type provided internally with a heater 2. The liquid mixture F concd. without penetrating the membrane 3 is introduced into the one block partitioned by the pervaporation membrane 3 of the membrane module unit 11 of the external heating type externally having a heater 10 and is reconcentrated. The membrane area is substantially the same and the initial cost is reduced as compared with the case of using only the internal heating type when, for example, 94% ethanol is going to be concentrated up to 99.8% by this method.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for membrane separation of mixed liquids, which has excellent mixed liquid separation properties by combining an internally heated membrane module unit and an externally heated membrane module unit. .

0002

[Prior Art] As an advanced separation technology that has been attracting attention in recent years, a mixed liquid to be separated is introduced into one compartment separated by a pervaporation membrane, and the mixed liquid is brought into contact with the active layer of the pervaporation membrane. In the other compartment, vapor from the permeate is brought into contact with the inert porous layer of the membrane, and the difference in chemical potential on both sides of the pervaporation membrane is used to separate the mixed liquid. A pervaporation method that performs concentration and concentration is known.

[0003] As a method for separating a mixed liquid by such a pervaporation method, for example, a plurality of membrane module units using pervaporation membranes similar to those described above are used, and the residual liquid of a first module unit is transferred to a second module unit. are connected in series so that the residual liquid of the n-1th module unit is introduced into the nth module unit, and the mixed liquid is heated before being introduced into each module unit. A mixed liquid separation method characterized by (see Japanese Patent Publication No. 2-21288)
In this case, it is known that a group of externally heated membrane module units are connected in series.

On the other hand, in a method of separating or concentrating by a pervaporation process using a polymer membrane, the polymer membrane is used in multiple stages and the temperature of the liquid mixture in the part to be separated or concentrated by each polymer membrane is set at a predetermined temperature. There has been a method for separating or concentrating a liquid mixture (see JP-A-58-128107), which is characterized by adjusting the temperature to a temperature range of Either an external heating type using a heat exchange device or an internal heating type using a heat exchanger installed inside the separation device is used.

As described above, heating the feed liquid introduced into each membrane module unit by either the external heating type or the internal heating type separates the mixed liquid with extremely excellent separation performance and permeability. It is known that it can also be concentrated. However, in the conventional method for separating mixed liquids using the above-mentioned pervaporation method, in a system in which multiple membrane module units are connected in series, the heating method for the liquid flowing into each membrane module unit is an external heating type or an internal heating type. Since all methods are standardized to one type or another, there is a waste in terms of cost and energy efficiency.

[0006] Therefore, the inventors of the present invention conducted various experiments on each of the internal heating type and external heating type membrane module units as described above, and compared their performance and equipment costs. As a result, the amount of membrane permeation was It was found that the internal heating type has superior performance in areas where there is a lot of water, that is, where there is a lot of moisture, and the external heating type has an advantage in terms of equipment cost in areas where the amount of membrane permeation is small, that is, where there is not much moisture. The present invention has been made by paying attention to each of the advantages.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to incorporate the advantages of the internal heating type and the external heating type by combining membrane module units of both heating types, thereby improving the performance of the conventional heating type. The object of the present invention is to provide a membrane separation method for mixed liquids that has superior performance and is inexpensive in equipment cost.

[0008]

[Means for Solving the Problems] That is, the method for membrane separation of a mixed liquid of the present invention is an internal heating type method in which a mixed liquid is separated by a pervaporation method through two partitions separated by a pervaporation membrane. and one external heating type membrane module unit similar to the above, or one heating type membrane module unit and the other heating type membrane module unit two or more, and This external heating type membrane module unit is characterized by using a plurality of both types of heating type membrane module units in appropriate combinations in series and/or parallel, and has a simple structure and low equipment cost. and an internally heated membrane module unit that can maintain the same temperature at all times while the mixed liquid is in contact with the membrane and achieve sufficient membrane performance with a small membrane area. By taking advantage of these advantages, a comprehensively superior membrane separation system can be obtained.

[0009]

[Embodiment] An embodiment to which the membrane separation method of the present invention is applied will be described below with reference to the drawings. First, in this example shown in the drawings, an ethanol mixture was supplied at a feed rate of 500 kg/h and 95°C as a 94% by weight mixed liquid F.
At a supply temperature of This mixed liquid F is separated or concentrated by a pervaporation method.

The vapor of the liquid component that has permeated the pervaporation membrane 3 of this first membrane module unit 1 is sucked from the other compartment by the vacuum pump 5 and cooled by the chiller 6, and is further cooled by the pump 7. It is taken out from inside the device. On the other hand, pervaporation film 3
The concentrated mixed liquid F that does not pass through the membrane module unit 1 is led out from the membrane module unit 1 by a pump 9, and is transferred to one section across the pervaporation membrane 3 of an external heating type membrane module unit 11 having an external heater 10. The vapor of the liquid component that has passed through the pervaporation membrane 3 is sucked into the vacuum pump 5 from the other compartment, cooled through the chiller 6, and then extracted from the device by the pump 7.

[0011] Furthermore, the mixed liquid F that does not pass through the pervaporation membrane 3 of this membrane module unit 11 is
For example, 99. 8% by weight of concentrated final product ethanol. As in the above example, an experiment in which the ethanol mixture was used as the mixed liquid F, was concentrated in the internal heating type membrane module unit 1, and then further concentrated in the external heating type membrane module unit 11 to the ethanol concentration of the final product. , 99% of the final ethanol product can be produced using only the internally heated membrane module unit. The table below shows the results of a comparison with a conventional experiment in which the concentration was 8% by weight.

In this table, case 1 has only an internal heating type membrane module unit and the final concentration is 99. A conventional example is shown in which the membrane module unit 1 is an internal heating type and the concentration is 99.9% by weight. After concentrating to 2% by weight, the final concentration was 99% by external heating type membrane module unit 11. 8% by weight is shown in this example,
Case 3 is an internally heated membrane module unit 1.
So 97. Up to 7% by weight, 99.9% by external heating type membrane module unit 11. 8% by weight is shown.

[0013] In this table, the membrane area of each membrane module unit is expressed as 100 in case 1, and the plant cost is also expressed as 100 in the case 1, and other values are expressed in comparison to that. There is. From this table, it can be seen that case 2 and case 3 can reduce the plant cost more than case 1, but case 2 requires less membrane area than case 3, and case 2 is the best because it is cheaper. It shows that there is.

That is, as in this embodiment shown in the drawings, 99% of the mixed liquid F containing 94% by weight of ethanol is mixed. 8
In a separation system that concentrates to more than 94% by weight, 99% by weight is used. up to 2% by weight by the internally heated membrane module unit 1 and 99% by weight. 2% to 99% by weight. When concentrating up to 8% by weight using the externally heated membrane module unit 11, the membrane area is almost the same as in the conventional case using only the internally heated membrane module unit, and the plant cost is reduced to about 95%. The experimental results revealed that.

In the above embodiment, one internal heating type membrane module unit 1 and one external heating type membrane module unit 11 are combined, but in the membrane separation method of the present invention, a combination of the above embodiments is used. It is not limited to
As mentioned above, the internal heating type membrane module unit 1
The number of external heating type membrane module units 11 may be plural, and the combination method may be series or parallel, or a combination thereof, depending on the type, properties, conditions, etc. of the mixed liquid to be separated and concentrated. shall be selected.

Further, the mixed liquid is not limited to the ethanol solution of the above embodiment, but any mixed liquid that has been conventionally applied to separation and concentration by the pervaporation method can be applied.

[0017]

[Effects of the Invention] As explained above, according to the membrane separation method for a mixed liquid of the present invention, by appropriately combining internal heating type and external heating type membrane module units, Compared to traditional methods using membrane module units of either type,
Its performance is excellent and the equipment cost is low.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of membrane separation equipment to which the membrane separation method for mixed liquids according to the present invention is applied.

[Explanation of symbols]

1 Internal heating type membrane module unit 2 Heater 3 Pervaporation membrane 10 Heater 11 External heating type membrane module unit F Mixed liquid

Claims (1)

[Claims] Claim 1: Uses a combination of an internally heated membrane module unit that separates a mixed liquid through two partitions separated by a pervaporation membrane, and an externally heated membrane module unit similar to the above. Membrane separation method for mixed liquids.