JP2009034660A - Distillation method and distillation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distillation method capable of achieving an excellent energy efficiency in the method for distilling a mixture liquid containing a polar solvent and a non-polar solvent, and to provide a distillation apparatus used in such a distillation method. <P>SOLUTION: In the method for distilling a liquid mixture containing the polar solvent and the non-polar solvent, the distillation method is characterized in that the liquid mixture is irradiated with a micro-wave. The polar solvent is preferably a solvent having relative permittivity of ≥4, and the non-polar solvent is preferably a solvent having relative permittivity of <4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a distillation method for distilling a mixed solution containing a polar solvent and a nonpolar solvent, and a distillation apparatus used for this distillation method. More specifically, the present invention does not require a distillation facility having a large number of theoretical plates, The present invention relates to a distillation method and a distillation apparatus excellent in efficiency.

  In the industrial field of high-mix low-volume production including the chemical industry, food industry, pharmaceutical industry, etc., the distillation operation is extremely important and is a general-purpose unit operation. Distillation is usually an operation in which a liquid mixture composed of two or more liquids having different boiling points is heated and vaporized to condense a vapor mainly composed of low-boiling components to separate components in the liquid mixture.

  Various types of distillation apparatuses are known as apparatuses used for such distillation operations. Usually, each component that has evaporated by heating is cooled and condensed to be taken out, and its composition is determined by the vapor pressure of each component. The ratio is almost the same, and distillation in only one stage (simple distillation) cannot achieve sufficient separation. Therefore, in order to separate a plurality of components having particularly close boiling points (vapor pressures are substantially equal), it is necessary to perform a distillation operation by using a plurality of multistage distillation columns having a large number of theoretical plates and increasing the reflux ratio. Therefore, heating and cooling are repeated, and there is a problem that energy efficiency is not good. For example, in Patent Document 1, in order to reduce the number of necessary distillation columns, it is attempted to divide one distillation column to have a plurality of distillation columns.

  However, even in the method described in Patent Document 1, it is necessary to use a multi-stage distillation column having a large number of theoretical plates, which requires a large facility and repeats heating and cooling, so that energy efficiency is sufficiently improved. There was no problem.

JP 11-312002 A

  The present invention has been made in view of such a situation, and in a method of distilling a mixed solution containing a polar solvent and a nonpolar solvent, a distillation method having a large number of theoretical plates is not required, and the distillation method is excellent in energy efficiency. It aims at providing the distillation apparatus used for such a distillation method.

  In order to achieve the above-mentioned object, the present inventors have conducted intensive studies. By irradiating a mixed liquid containing a polar solvent and a nonpolar solvent with microwaves and performing distillation by microwave irradiation, The present inventors have found that the above object can be achieved and have completed the present invention.

That is, according to the present invention,
(1) A method of distilling a mixed solution containing a polar solvent and a nonpolar solvent, the method comprising irradiating the mixed solution with microwaves,
(2) The polar solvent is a solvent having a relative dielectric constant of 4 or more, and the nonpolar solvent is a solvent having a relative dielectric constant of less than 4, and (3) a polar solvent, A distillation tank for containing a mixed solution containing a nonpolar solvent, a microwave irradiation device for irradiating the mixed solution in the distillation tank with a microwave, and the microwave connected to the distillation tank. A distillation apparatus comprising: a cooling device that cools and liquefies the gas generated by the irradiation; and a recovery tank for recovering the solvent liquefied by the cooling device;
Is provided.

  The present invention performs distillation of a mixed solution by irradiating a mixed solution containing a polar solvent and a nonpolar solvent with microwaves. And while the polar solvent which has the property of being easy to perform molecular motion by microwave irradiation can be preferentially heated, the non-polar solvent which is difficult to move by microwave irradiation is hardly heated. As a result, since the preferentially heated polar solvent selectively evaporates, distillation is possible without heating to the boiling point of the polar solvent, and the separation capability is high. Therefore, even if a large reflux ratio is not applied using a distillation apparatus having a large theoretical plate number (that is, a distillation apparatus having a small theoretical plate number and a small reflux ratio), only polar solvent can be selectively recovered. . Therefore, there is little heat loss and it is excellent in energy efficiency.

Hereinafter, the distillation method of the present invention will be described in detail.
The distillation method of the present invention is characterized in that microwaves are irradiated to a mixed solution containing a polar solvent and a nonpolar solvent.

  It does not specifically limit as a polar solvent and a nonpolar solvent which comprise the liquid mixture distilled by the method of this invention, For example, the following solvents can be used.

  That is, the polar solvent is not particularly limited as long as it has polarity and is usually used in various fields, but the relative dielectric constant is preferably 4 or more, more preferably 10 or more, Preferably it is 15 or more. The relative dielectric constant is preferably 100 or less.

  Examples of such a polar solvent include water, methanol, ethanol, propanol, acetic acid, acetone, acetonitrile, acrylonitrile, methacrylonitrile, methylene chloride, and the like.

  The nonpolar solvent is not particularly limited as long as it has a low polarity and is usually used in various fields, and its relative dielectric constant is preferably less than 4.

  Examples of such nonpolar solvents include hexane, benzene, toluene, styrene, cyclohexane, cyclopentane, butadiene, isoprene, and the like.

  The combination of the polar solvent and the nonpolar solvent constituting the mixed solution distilled by the method of the present invention is not particularly limited. However, since the effect of the present invention becomes more remarkable, the difference in boiling point is preferably 30 ° C. or less. It is preferable that the combination is such that it is 20 ° C. or less. In addition, it is preferable that the boiling point of a nonpolar solvent is higher than a polar solvent.

  Specific examples of the combination of the polar solvent and the nonpolar solvent constituting the mixed liquid distilled by the method of the present invention include, for example, methanol / cyclohexane, acrylonitrile / styrene, acetone / cyclopentane, acrylonitrile / butadiene, acrylonitrile / isoprene, and the like. Is mentioned.

  Moreover, in this invention, you may use 2 or more types of solvents as a polar solvent and / or a nonpolar solvent which comprise a liquid mixture. That is, the mixed solution may be a combination of two or more polar solvents and one nonpolar solvent, or may be a combination of one polar solvent and two or more nonpolar solvents. Furthermore, a combination of two or more polar solvents and two or more nonpolar solvents may be used. In addition, as a combination in the case of using such 2 or more types of polar solvents and / or a nonpolar solvent, acrylonitrile / butadiene / isoprene, acrylonitrile / methanol / butadiene, etc. are mentioned, for example.

  The mixing ratio of the polar solvent to the nonpolar solvent in the mixed solution is usually a polar solvent: nonpolar solvent = 1: 99 to 99: 1, preferably 1:99 to 20:80 in terms of weight ratio. When there is too little content of a nonpolar solvent in a liquid mixture, the effect of this invention may become small.

  The method of irradiating the mixed solution with microwaves is not particularly limited. For example, a method of putting the mixed solution into a predetermined distillation tank and irradiating microwaves toward the distillation tank can be mentioned. In addition, as a distillation tank, the chemical distillation industry, food industry, pharmaceutical industry etc. WHEREIN: The normal distillation tank generally used in the case of distillation is used, and what was equipped with the stirring apparatus may be used. In addition, a cooling device for cooling the vaporized component and thereby liquefying the vaporized component is connected to the distillation tank in the vicinity of the upper portion thereof. Further, a recovery tank is connected to the cooling device and liquefied by the cooling device. It is common to allow the recovered components to be recovered. In addition, a packed tower and a reflux facility may be installed in the upper part of the distillation tank to give a certain number of theoretical plates. A multi-stage distillation column can be installed, and microwaves can be irradiated not only at the bottom kettle but also at each stage.

  The microwave is preferably an electromagnetic wave having a wavelength of 1 m (frequency: 300 MHz) to 1 mm (frequency: 300 GHz). In the present invention, the microwave applied to the mixed solution has a wavelength of preferably 60 cm (frequency: 500 MHz) to 1.5 mm (frequency: 200 GHz), particularly 30 cm (frequency: 1 GHz) to 3 cm (frequency: It is preferable to use one in the range of 10 GHz).

  Microwaves can usually be generated by a microwave generator. In the present invention, the output of the microwave generator upon irradiation with microwaves is preferably in the range of 200 W to 500 kW, more preferably in the range of 300 W to 10 kW. Note that the microwave generator may be of a magnetron type, a klystron type, or a gyrotron type. If the output of the microwave generator is too low, heating of the polar solvent in the mixed solution becomes insufficient, and the polar solvent may not be selectively evaporated. On the other hand, if the output is too high, there is a possibility that the polar solvent will boil too rapidly.

  In the present invention, the microwave output is not necessarily constant, and may be changed as necessary. For example, the output may be the same between the start of microwave irradiation and the start of boiling of the polar solvent and after the start of boiling of the polar solvent, or may be different. By making the microwave output different before and after boiling of the polar solvent, for example, the accuracy of the separated components in distillation can be controlled.

  And the distillation by the microwave in this invention advances as follows, for example. That is, a mixed liquid containing a polar solvent and a nonpolar solvent is placed in a distillation tank, and irradiated with microwaves generated by a microwave generator in a state of being placed in the distillation tank, as shown in FIG. The polar solvent undergoes molecular motion in the mixed solution, whereby the liquid temperature of the mixed solution rises continuously. In addition, FIG. 1 is a graph which shows the relationship between the microwave irradiation time and the temperature of a liquid mixture in the distillation by the microwave of this invention.

  Thereafter, the liquid temperature of the mixed liquid rises to a predetermined temperature (temperature T1 shown in FIG. 1, where T1 may be lower than the boiling point of the polar solvent), and the temperature rises at a predetermined temperature (temperature T1 shown in FIG. 1). Stops or decreases, and boiling of the polar solvent starts. And energy by microwave irradiation continues to be preferentially consumed for vaporization by boiling of the polar solvent, and finally boiling of the polar solvent is completed. In addition, the component vaporized by the distillation by the microwave of the present invention is cooled by a cooling device connected to the distillation tank, and is thereby liquefied and collected in a recovery tank connected to the cooling device. That is, by the distillation method of the present invention, components in the mixed solution are separated into a distillation tank and a recovery tank, respectively. In this way, distillation by microwaves in the present invention is performed.

  In the microwave distillation according to the present invention thus performed, a distillation residue mainly containing a nonpolar solvent remains in the distillation tank, while a distillate mainly containing the polar solvent moves to the recovery tank; Become.

  As described above, according to the distillation method of the present invention, a polar solvent having the property of being easily molecularly moved by irradiation with microwaves can be preferentially heated, so that a distillation facility having a large number of theoretical plates is not required and energy efficiency is excellent. .

  In addition, in the distillation by microwave in the present invention, after the boiling of the polar solvent, the component that undergoes molecular motion by microwave irradiation such as the polar solvent hardly remains, so even if microwave irradiation continues, The temperature of the mixed solution will hardly increase.

While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.
For example, as long as the effects of the present invention are not impaired, the present invention may be used in combination with a distillation method other than the microwave distillation method of the present invention. Further, for example, a method may be employed in which heating is performed with a heater or the like up to a temperature at which the polar solvent and the nonpolar solvent in the mixed solution are not substantially vaporized, and then switching to microwave heating and distillation.

  The present invention will be specifically described below with reference to examples and comparative examples. [Part] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited only to these examples.

Example 1
First, a distillation apparatus shown in FIG. 2 was prepared.
The distillation apparatus shown in FIG. 2 has a configuration in which a distillation flask 2 for containing a mixed solution 4 distilled by the method of the present invention is provided in a microwave heating furnace 6. The microwave can be irradiated toward the mixed liquid 4 inside. Specifically, the microwave can be generated by the microwave oscillator 8, and the generated microwave is guided into the microwave heating furnace 6 through the waveguide 10, thereby being used for distillation. The mixed solution 4 in the flask 2 is irradiated. The microwave heating furnace 6 is provided with a door (not shown) that can be opened and closed so that a sample can be taken in and out, and the inside of the microwave heating furnace 6 can be sealed by closing the door. Yes.

  And the component vaporized in the mixed liquid 4 by the microwave irradiated from the waveguide 10 passes through the glass tube 12 and is cooled and liquefied in the cooling tube 14, and finally passes through the glass tube 16. The liquid is recovered in the recovery flask 18 connected to the cooling pipe 14. In the distillation apparatus shown in FIG. 2, the distillation flask 2 containing the mixed solution 4 is disposed on the magnetic stirrer 20, and the stirrer 22 in the distillation flask 2 is rotated by the magnetic stirrer 20. Thus, the liquid mixture 4 can be stirred. The cooling pipe 14 can cool the gas and / or liquid inside the cooling pipe 14 by passing the refrigerant 14a.

  And the distillation by a microwave was performed using the distillation apparatus prepared above. Specifically, first, a methanol / cyclohexane mixed solution (methanol: cyclohexane = 5 parts: 95 parts) was prepared as the mixed solution 4 to be subjected to distillation. Note that methanol has a boiling point of 64.7 ° C. and a relative dielectric constant of 33.0, and cyclohexane has a boiling point of 80.7 ° C. and a relative dielectric constant of 2.0.

  Next, 100 parts of the methanol / cyclohexane mixture prepared above is put into the distillation flask 2, and the methanol / cyclohexane mixture put into the distillation flask 2 is stirred by the magnetic stirrer 20 and the stirrer 22. Stirring was performed at 400 rpm.

  Then, with the methanol / cyclohexane mixed liquid being stirred, the door of the microwave heating furnace 6 is closed, the inside of the microwave heating furnace 6 is closed, and then the methanol / cyclohexane in the distillation flask 2 is checked with a data logger. Data collection of cyclohexane mixture temperature, vapor temperature, and microwave output was started, followed by microwave irradiation. In this example, the vapor temperature was measured in the vicinity of the top of the glass tube 12 of the distillation apparatus shown in FIG. Moreover, the output of the microwave oscillator 8 at the time of microwave irradiation was 364 W, and the frequency was 2.45 GHz. The data collected by the data logger is graphed and shown in FIG. In FIG. 3A, in the vertical axis direction, the microwave output is shown below, and the methanol / cyclohexane mixture temperature and vapor temperature are shown above.

  As can be confirmed from FIG. 3 (A), the temperature of the methanol / cyclohexane mixture continuously increased after the start of microwave (MW) irradiation, and when 330 seconds had elapsed from the start of irradiation, The temperature of the cyclohexane mixture reached about 57 ° C., the methanol / cyclohexane mixture boiled, and steam began to be generated from the mixture. Then, as can be confirmed from FIG. 3A, even when the microwave irradiation was continued, the temperature of the methanol / cyclohexane mixed solution did not rise from about 57 ° C., and continued to boil. The temperature of the vapor generated from the methanol / cyclohexane mixture was also constant at about 52 ° C. Thereafter, after 736 seconds from the start of microwave irradiation, boiling was almost not confirmed, and microwave irradiation was terminated.

  In Example 1, finally, the amount of the distillation residue remaining in the distillation flask 2 was 94 parts, and the remaining amount of methanol was 6165 ppm. Moreover, the methanol concentration in the distillate (about 6 parts) recovered in the recovery flask 18 was 73%, and the cyclohexane concentration was 27%.

Comparative Example 1
In the distillation apparatus in FIG. 2, the microwave heating furnace 6, the microwave oscillator 8, and the waveguide 10 are not used. Instead, the flask 2 is adjusted with a mantle heater (rated 100 W, adjusted to 80% output by the slider). The methanol / cyclohexane mixture was distilled by heating.

  In Comparative Example 1, as in Example 1, each data of the methanol / cyclohexane mixed solution temperature and the vapor temperature in the distillation flask 2 was collected by the data logger. However, in the comparative example 1, since the microwave irradiation was not performed, the microwave output data was not measured. The data collected by the data logger is graphed and shown in FIG.

  As can be seen from FIG. 3B, after the start of heating with the mantle heater, the temperature of the methanol / cyclohexane mixture continuously rises, and when 340 seconds have elapsed from the start of heating, the methanol / cyclohexane The temperature of the mixture reached about 62 ° C., the methanol / cyclohexane mixture boiled, and steam began to be generated from the mixture. As can be seen from FIG. 3B, the temperature of the methanol / cyclohexane mixed solution continued to rise as the heating was continued thereafter. At this time, the temperature of the vapor generated from the methanol / cyclohexane mixture was constant at about 52 ° C. When the temperature reached about 81 ° C., higher temperature steam (steam of about 65 ° C.) was generated.

  In Comparative Example 1, finally, the amount of distillation residue remaining in the distillation flask 2 was 90 parts, and the remaining amount of methanol was not detected. The methanol concentration in the distillate (about 10 parts) recovered in the recovery flask 18 was 50%, and the cyclohexane concentration was 50%.

As described above, in Comparative Example 1 in which distillation was performed by heating with a mantle heater, the concentration of cyclohexane in the distillate recovered in the recovery flask 18 was high, and separation was insufficient. On the other hand, in Example 1 in which distillation by microwave was performed, the methanol concentration in the distillate recovered in the recovery flask 18 was high, and an excellent separation ability was shown.
Further, in Comparative Example 1 in which distillation by heating with a mantle heater was performed, distillation could not be started unless the temperature of the methanol / cyclohexane mixed solution reached about 62 ° C., but in Example 1 irradiated with microwaves, about 1 Distillation could be performed at 57 ° C. and there was little heat loss.

FIG. 1 is a graph showing the relationship between the microwave irradiation time and the temperature of the mixed solution in the microwave distillation of the present invention. FIG. 2 is a schematic view of a distillation apparatus according to an embodiment of the present invention. 3A is a graph showing measurement data in the distillation method according to the example of the present invention, and FIG. 3B is a graph showing measurement data in the distillation method according to the comparative example.

Explanation of symbols

2 ... Distillation flask 4 ... Mixture 6 ... Microwave heating furnace 8 ... Microwave oscillator 10 ... Waveguide 12 ... Glass tube 14 ... Cooling tube 16 ... Glass tube 18 ... Recovery flask 20 ... Magnetic stirrer 22 ... Stir bar

Claims (3)

  A method for distilling a mixed solution containing a polar solvent and a nonpolar solvent, the method comprising irradiating the mixed solution with microwaves.   The distillation method according to claim 1, wherein the polar solvent is a solvent having a relative dielectric constant of 4 or more, and the nonpolar solvent is a solvent having a relative dielectric constant of less than 4. A distillation tank for containing a mixed solution containing a polar solvent and a nonpolar solvent;
A microwave irradiation device for irradiating the mixed solution put in the distillation tank with microwaves;
A cooling device connected to the distillation tank for cooling and liquefying the gas generated by the microwave irradiation;
And a recovery tank for recovering the solvent liquefied by the cooling device.

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