JP2009202056A - Solvent removing method and solvent removing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a foam formation produced in distilling a process liquid and normally remove solvent with a good accuracy from the process liquid. <P>SOLUTION: The solvent removing method comprises the step of removing an organic solvent 1 from the process liquid 2 by distilling the process liquid 2 containing the organic solvent 1 under a reduced-pressure environment, and, as a pretreatment process of the distillation, the process liquid 2 is dispersed to deaerate the gas existing in solution in the process liquid in a temperature range producing no quality deterioration of the process liquid 2 and under the reduced-pressure environment in a range of temperatures producing no boil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solvent removal method for removing the organic solvent from the treatment liquid by distilling the treatment liquid containing the organic solvent in a reduced pressure environment, and a solvent removal apparatus used directly for carrying out the method.

Conventionally, as this type of solvent removal technology, for example, as a solvent removal apparatus (a circulation system capable of circulating a treatment liquid containing an organic solvent is provided, and the treatment liquid is contained in a deaeration can incorporated in the circulation system). Is provided with a dispersion means that can freely discharge and discharge, a pressure reduction means for making the inside of the deaeration can be in a reduced pressure environment, a temperature raising means for raising the temperature of the processing liquid is provided, and an operation control unit that controls the operation thereof. The dispersion means, the decompression means, and the ascending temperature are set such that the temperature of the treatment liquid is raised to a temperature range in which the organic solvent in the treatment liquid boils, and the organic solvent and water vapor are evaporated and separated from the treatment liquid. A solvent removal apparatus configured to control operation of the temperature means), while circulating the treatment liquid in the circulation system, the temperature of the treatment liquid is raised by the temperature raising means, and the desorption is performed. The inside of the air can has a reduced pressure environment, By distributing discharging the processing liquid by, it was implementing a method for separating and removing (distillation) the organic solvent and water from the treatment liquid is evaporated by boiling from the processing liquid.
Such a prior art is widely known among those skilled in the art. However, since there is no patent document or the like that specifically refers to the solvent removal technique, no prior art document is shown.

According to the conventional solvent removal technique described above, during the distillation, the dissolved gas in the treatment liquid cannot be completely removed, so that dissolved gas is generated from the treatment liquid accumulated in the degassing can, and the treatment liquid is removed. There is a phenomenon of foaming in the space above the liquid level.
When foaming is severe, there is a risk that the bubbles may enter the condensation mechanism side of the gas to be distilled, which may hinder the distillation process.

  Accordingly, an object of the present invention is to provide a solvent removal technique capable of solving the above-described problems, suppressing foaming that occurs during distillation of the treatment liquid, and normally removing the solvent from the treatment liquid with high accuracy.

  A first characteristic configuration of the present invention is a solvent removal method for removing the organic solvent from the treatment liquid by distilling the treatment liquid containing the organic solvent under a reduced pressure environment, wherein the treatment is performed as a pretreatment step for distillation. The processing liquid is dispersed and the dissolved gas in the processing liquid is degassed in a reduced pressure environment where the quality of the liquid does not deteriorate and in a temperature range where boiling does not occur. In this solvent removal method, first, a pretreatment step for degassing dissolved gas (a degassing step shown later) is performed, and then a step of removing the organic solvent from the treatment liquid by distillation (a distillation step shown later). Execute.

According to the first characteristic configuration of the present invention, as the pretreatment step for distillation, the treatment liquid is dispersed in a temperature range in which the quality of the treatment liquid does not deteriorate and in a reduced pressure environment in a temperature range in which boiling does not occur. Therefore, the dissolved gas is mainly vaporized in the dispersed state in the space inside the degassing can, and the dissolved gas is removed before the dispersed processing solution falls and accumulates in the degassing can. Degassing can be performed efficiently. Therefore, when carrying out distillation, the target treatment liquid does not contain dissolved gas or can be in a state where the dissolved gas is less than in the conventional case, and the foaming caused by the dissolved gas is a degassing can. It becomes possible to prevent the occurrence of violence in the inside.
As a result, it is possible to prevent foaming in the degassing can from reaching the condensation mechanism used for distillation, and smoothly perform the distillation step, thereby efficiently removing the organic solvent from the treatment liquid.
In addition, since the pretreatment process described above is performed in a temperature range that does not cause quality deterioration of the treatment liquid and in a reduced pressure environment in a temperature range that does not boil, the pretreatment process causes quality deterioration of the treatment liquid. There is nothing.

  A second characteristic configuration of the present invention is that the temperature of the processing liquid is raised within the temperature range in the pretreatment step.

According to the second characteristic configuration of the present invention, in addition to being able to achieve the above-described operational effects according to the first characteristic configuration of the present invention, the processing liquid is dissolved in the above-described range of conditions, thereby being dissolved. Gas vaporization is promoted, and dissolved gas can be efficiently degassed from the treatment liquid.
Therefore, it is possible to further suppress foaming in the degassing can during distillation.

  According to a third feature of the present invention, there is provided a circulation system capable of circulating a treatment liquid containing an organic solvent, and dispersion means capable of dispersing and discharging the treatment liquid in a degassing can incorporated in the circulation system. In the solvent removal apparatus provided with a pressure reducing means for providing a reduced pressure environment inside the degassing can and having a temperature raising means capable of raising the temperature of the processing liquid, a temperature range in which the quality of the processing liquid does not deteriorate And after performing a degassing step of degassing the dissolved gas in the treatment liquid by dispersing the treatment liquid in a reduced pressure environment in a temperature range that does not boil, the distillation is performed on the treatment liquid from the treatment liquid. An operation control unit that controls the operation of the dispersing means, the pressure reducing means, and the temperature raising means is provided so as to execute a distillation step for removing the organic solvent.

According to the third characteristic configuration of the present invention, the solvent removal method according to the first or second characteristic configuration of the present invention can be implemented more reliably and efficiently.
That is, the operation control unit disperses the treatment liquid and degass the dissolved gas in the treatment liquid in a reduced pressure environment in which the quality of the treatment liquid does not deteriorate and does not boil. After performing the deaeration process, the dispersion means, the pressure reducing means, and the temperature raising means are controlled to operate so as to execute a distillation step of removing the organic solvent from the treatment liquid by distillation with respect to the treatment liquid. In the degassing step, the dissolved gas can be mainly degassed before evaporating the organic solvent from the treatment liquid. In the subsequent distillation step, the target treatment liquid does not contain the dissolved gas. Or it can be made into a state where there is little dissolved gas compared with the past, and it becomes possible to prevent now that foaming caused by dissolved gas is generated violently in the deaeration can.
As a result, it is possible to prevent foaming in the degassing can from reaching the condensation mechanism used for distillation, and smoothly perform the distillation step, thereby efficiently removing the organic solvent from the treatment liquid.
Further, since the degassing step described above is performed in a reduced pressure environment in a temperature range in which the quality of the processing liquid does not deteriorate and in a temperature range in which the processing liquid does not boil, the quality of the processing liquid is deteriorated by the pretreatment step. There is nothing.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the parts indicated by the same reference numerals as those in the conventional example indicate the same or corresponding parts.

FIG. 1 shows an example of a solvent removal apparatus S that implements the solvent removal technique of the present invention. The solvent removal apparatus S1 of this embodiment is a process that includes an organic solvent 1 (for example, methyl isobutyl ketone or ethanol). A circulation system R that can freely circulate a liquid (for example, paint, liquid fermented food, etc.) 2 is provided, and a dispersion means 3a that can disperse and discharge the treatment liquid 2 in a deaeration can 3 incorporated in the circulation system R. A depressurizing means 4 for making the inside of the degassing can 3 a depressurizing environment, a temperature raising means 5 capable of raising the temperature of the treatment liquid 2 is provided, the dispersing means 3a, the depressurizing means 4 and the An operation control unit 6 that controls the temperature raising means 5 and the like is provided.
And according to the said apparatus, the organic solvent 1 can be removed from the said process liquid 2 by distillation, and the process liquid 2 with high purity can be refine | purified.
Here, the boiling point of the organic solvent contained in the treatment liquid and the dissolved gas dissolved in the treatment liquid to be degassed in the present application (specifically, inert gases such as oxygen, nitrogen and carbon dioxide) The temperature at which the gas is degassed from the processing solution is lower in the latter than in the former under the same reduced pressure.

As shown in the figure, the circulation system R has an annular structure including a pipe 9 extending from the degassing can 3 to the degassing can 3 via a discharge pump 7 and a heat exchanger (corresponding to the temperature raising means 5) 5A. It is configured.
The treatment liquid 2 accumulated in the degassing can 3 is degassed from the pipe 9 connected to the lower end of the degassing can 3 through the discharge pump 7 and the heat exchanger 5A as the discharge pump 7 is driven. The degassing can 3 is returned to the deaeration can 3 through a pipe 9 connected to the upper end of the can 3.

  The said deaeration can 3 is comprised with the metal containers, and is comprised by the airtight structure so that the inner space part can be maintained in a pressure-reduced state. And while the circulation system R is connected in communication, the condensing device 10 for condensing the gasified by distillation in the degassing can 3 and the depressurization using the inner space of the degassing can 3 as a depressurized environment An apparatus (corresponding to the decompression means 4) 4A and the like are connected in communication via a pipe 12 different from the pipe 9.

  The dispersion means 3a, for example, achieves dispersion by discharging treated water from a nozzle in a mist form (or water droplet form, water film form), or by dropping the treatment liquid 2 onto a rotating dispersion plate. In addition to this, known dispersing means can be used.

  The heat exchanger 5A performs heat exchange through the flow path wall by bringing a warm body such as hot water or steam into contact with the outer periphery of the flow path wall, and adds heat to the treatment liquid 2 flowing in the flow path. The treatment liquid temperature is increased. Incidentally, temperature control of the warm body, contact time control to the flow path wall, and the like are performed by the operation control unit 6.

The decompression device 4A is constituted by a vacuum pump connected to the most downstream side of the pipe 12, and by operating the vacuum pump, the inside of the deaeration can 3 can be made a decompressed environment, It is possible to draw the dissolved gas, organic solvent, water vapor, etc. vaporized in the deaeration can 3 into the condenser 10 side.
The degree of pressure reduction is controlled by controlling the operation status of the vacuum pump by the operation control unit 6.

The condensing device 10 includes a heat exchanger 10A and a receiving tank 10B.
The heat exchanger 10A is configured to perform heat exchange through the flow path wall by bringing cooling water into contact with the outer peripheral portion of the flow path wall, and extract heat from the gas flowing in the flow path to condense. is there. The condensed organic solvent is accommodated in the receiving tank 10B and collected.

The operation control unit 6 removes the organic solvent 1 from the treatment liquid 2 with three control contents from 1 to 3 passes, and each device device (dispensing pump 7, dispersion means 3a, heat exchanger 5A). The pressure reducing device 4A and the heat exchanger 10A) are controlled.
The operation control is performed based on information from various sensors (not shown) and meters (not shown) respectively installed at corresponding positions in the solvent removal apparatus S1, and each flow path is further controlled. The opening / closing operation control of the opening / closing valve (not shown) is also performed by the operation control unit 6.

The solvent removal method using the solvent removal apparatus S1 will be described.
[1] The first pass is a temperature range in which quality deterioration of the treatment liquid 2 does not occur as a pretreatment step for distillation while circulating the treatment liquid 2 in the circulation system R (in the embodiment, 80 ° C. or less). In a reduced pressure environment where the organic solvent does not boil (for example, a temperature of 25 to 30 ° C. and an atmospheric pressure of −0.094 MPa), the treatment liquid 2 is dispersed by the dispersing means 3a to dissolve dissolved gas in the liquid. Deaerate.
[2] In the second pass, the dissolved gas is degassed by a process substantially the same as the process [1], but the treatment liquid temperature is kept within the temperature range by the heat exchanger 5A. The temperature is raised (for example, 35 to 40 ° C.). By this step, most of the dissolved gas in the treatment liquid 2 is degassed.
[3] The third pass enters the distillation step while circulating the treatment liquid 2 in the circulation system R. The treatment liquid 2 is heated to about 50 ° C. by the heat exchanger 5A, and is dispersed in the degassing can 3 by the dispersing means 3a. By this process, azeotropy occurs at the moment of dispersion in the treatment liquid 2, and at the stage where it accumulates in the degassing can 3, the heat of vaporization is deprived and the azeotrope ends, and foaming from the liquid is observed. Disappear. Then, the organic solvent 1 vaporized by azeotropy is introduced into the condenser 10 and recovered.

As described above, according to the solvent removal technique, dissolved gas can be efficiently degassed from the treatment liquid 2 in the pretreatment stage of distillation, and foaming caused by the dissolved gas is generated violently in the degassed can. This makes it possible to carry out the subsequent distillation in a state in which this is prevented.
As a result, it is possible to prevent foaming in the degassing can from reaching the condensation mechanism used for distillation, and smoothly perform the distillation step, thereby efficiently removing the organic solvent from the treatment liquid.
In addition, since the pretreatment process described above is performed in a temperature range that does not cause quality deterioration of the treatment liquid and in a reduced pressure environment in a temperature range that does not boil, the pretreatment process causes quality deterioration of the treatment liquid. There is nothing.

[Another embodiment]
Other embodiments will be described below.

<1> The said solvent removal method is not restricted to the specification demonstrated in previous embodiment, It can change suitably.
For example, instead of the operation control divided into the three passes described in the previous embodiment, the control is a two-stage control that performs the first pass (or the second cell) and the third pass described in the previous embodiment. Or, it may be one that performs control of four or more passes.
Each control temperature, control pressure, and the like are not limited to the set values of the previous embodiment, and can be changed as appropriate. In addition, if the target processing solution is different, it is preferable to change the setting value to be suitable for the processing solution.
FIG. 2 shows six examples in which the temperature condition, the decompression condition, etc. in the control are varied. In these methods, control divided into four passes is performed, and in any method, the solvent can be removed without foaming.
Moreover, the reduced pressure state in the deaeration can is carried out while maintaining a constant value in any example. Instead of this method, it is conceivable to increase the degree of vacuum when entering the distillation process, but in this case, the treatment liquid accumulated in the degassing can is suddenly boiled due to the lowering of the boiling point, and bubbles are generated. Because it is easy to cause, attention is necessary.
<2> The solvent removal apparatus S is not limited to that described in the previous embodiment. For example, as illustrated in FIG. 3, the circulation tank 13 is provided in the circulation system R separately from the deaeration can 3. The structure which provides may be sufficient. In this case, it is preferable to provide a liquid feed pump 14 between the circulation tank 13 and the deaeration can 3. Further, according to the solvent removal apparatus S2 of this embodiment, since the treatment liquid 2 can be stored in the circulation tank 13, the inner volume of the degassing can 3 can be reduced, and this degassing requiring a high degree of vacuum. Cost reduction can be achieved by reducing the size of the can 3.

  In addition, as mentioned above, although the code | symbol was written in order to make contrast with drawing convenient, this invention is not limited to the structure of an accompanying drawing by this entry. In addition, it goes without saying that the present invention can be carried out in various modes without departing from the gist of the present invention.

Schematic diagram showing the solvent removal device Explanatory drawing showing a control example Schematic showing the solvent removal apparatus of another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic solvent 2 Processing liquid 3 Deaeration can 3a Dispersing means 4 Depressurizing means 5 Temperature raising means 6 Operation control part R Circulation system

Claims (3)

A solvent removal method for removing the organic solvent from the treatment liquid by distilling the treatment liquid containing the organic solvent under a reduced pressure environment,
As a pretreatment step for distillation, a solvent that degass the dissolved gas in the treatment liquid by dispersing the treatment liquid in a temperature range that does not cause deterioration of the quality of the treatment liquid and in a reduced pressure environment that does not boil Removal method.   The solvent removal method according to claim 1, wherein in the pretreatment step, the temperature of the treatment liquid is raised within the temperature range. A circulation system capable of circulating a treatment liquid containing an organic solvent is provided, and a dispersion means capable of dispersing and discharging the treatment liquid is provided in a deaeration can incorporated in the circulation system, and the inside of the deaeration can is depressurized. A solvent removing apparatus provided with a pressure reducing means for making an environment, and provided with a temperature raising means capable of raising the temperature of the treatment liquid,
After performing a degassing step of degassing the dissolved gas in the treatment liquid by dispersing the treatment liquid in a reduced pressure environment in a temperature range where the quality of the treatment liquid does not deteriorate and in a temperature range where boiling does not occur. Solvent removal provided with an operation control unit for controlling operation of the dispersing means, the pressure reducing means, and the temperature raising means so as to execute a distillation step of removing the organic solvent from the treatment liquid by distillation of the treatment liquid. apparatus.

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