JP6555034B2 - Organic solvent recovery device - Google Patents

Description

  The present invention relates to an organic solvent recovery apparatus suitable for treatment of a highly reactive organic solvent-containing gas such as ketone or diene.

  In recent years, emission concentration regulations for air pollution-causing substances such as organic solvents have been strengthened, and a technique for reducing the exhaust gas concentration at the outlet of a gas processing apparatus that performs processing of organic solvents is required.

  The gas treatment apparatus has a plurality of adsorption tanks filled with granular activated carbon or activated carbon fiber as an adsorbent, an adsorption means for supplying a gas to be treated containing an organic solvent to each adsorption tank, A desorption means for ejecting water vapor is provided, and the step of adsorbing the organic solvent-containing gas to be treated in the adsorption tank and the step of desorbing the organic solvent adsorbed on the adsorbent with water vapor are alternately performed. The structure which provided the system which collect | recovers organic solvents is utilized (for example, refer patent document 1, 2).

  However, in the gas treatment system, particularly when a highly reactive organic solvent such as a ketone or diene is treated, the solvent remaining in the step of desorbing the organic solvent adsorbed by the adsorbent with water vapor, There was a problem that the solvent reacted on the adsorbent and caused abnormal heat generation.

  Therefore, as a method of treating the organic solvent having high reactivity, a method of depressurizing an adsorption tank at the time of adsorption treatment and performing desorption with low-temperature steam at 60 ° C. to 85 ° C. (for example, see Patent Document 3), before and after the adsorption treatment When the temperature inside the adsorption tank is replaced with an inert gas (see, for example, Patent Document 4), the activated carbon mounted in the adsorption tank and the exhaust gas outlet side, and the detected temperature reaches a certain condition A method of introducing nitrogen gas into the gas (see, for example, Patent Document 5) has been proposed.

  It is possible to increase safety when adsorbing and desorbing a highly reactive organic solvent by using the above technique, but when a large amount of highly reactive organic solvent adheres to activated carbon as an adsorbent, There was a problem that the risk of abnormal heat generation increased.

  The possibility of a large amount of highly reactive organic solvent adhering to the activated carbon is that the condenser from the tank drain pipe connected to the lower part of the adsorption tank in order to discharge the drain water condensed in the adsorption tank during the desorption process The condensate that has been cooled and recovered in (1) flows backward.

  In order to solve this problem, by providing a baffle consisting of a support column and a backflow prevention plate at the upper part of the outlet of the adsorption tank of the tank drain pipe connected to the lower part of the adsorption tank, the reverse flow of the organic solvent from the tank drain pipe is prevented. A technique for preventing this has been proposed (for example, see Patent Document 6).

  However, in such a solution, it is possible to prevent the backflow of the condensate from the tank drain pipe, but the condensate staying in the tank drain pipe is heated by the heat of water vapor in the desorption process, causing bumping. Therefore, it is difficult to completely prevent the generated droplets from adhering to the adsorbent, and a safer recovery method has been desired.

Japanese Patent Laid-Open No. 51-38278 Japanese Examined Patent Publication No. 64-11326 JP-A-63-264119 JP2013-71115A JP 2000-5554 A JP 2003-53131 A

  This invention makes it a subject to provide the organic-solvent collection | recovery apparatus which can be processed safely, when processing the organic solvent with high reactivity.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have reached the present invention. That is, the present invention is as follows.

1. It comprises a plurality of adsorption tanks filled with an adsorbent that adsorbs an organic solvent by contacting a gas to be treated containing an organic solvent, and desorbs the adsorbed organic solvent by contacting water vapor,
An adsorption step of adsorbing an organic solvent to the adsorbent by supplying a gas to be treated to the adsorbent filled in the adsorption tank and discharging it as a treatment gas;
A desorption step of desorbing the organic solvent from the adsorbent by supplying water vapor to the adsorbent filled in the adsorption tank and discharging it as a desorption gas containing the organic solvent;
Repeat alternately,
An organic solvent recovery device that cools and recovers a desorption gas containing an organic solvent discharged in a desorption process with a condenser,
An organic solvent recovery apparatus comprising a system for cooling a tank drain pipe connected to the lower part of the adsorption tank in order to discharge drain water condensed in the adsorption tank in the desorption step.
2. 2. The organic solvent recovery according to 1 above, wherein in the means for cooling the tank drain pipe, a temperature detector is installed in the tank drain pipe, and the condensate temperature in the tank drain is set to be equal to or lower than the azeotropic temperature of the organic solvent and water. apparatus.
3. As a means for cooling the tank drain pipe, a double pipe type cooler is connected to the tank drain pipe, and the tank drain pipe is cooled by introducing cooling water and cold water into the double pipe type cooler. 2. The organic solvent recovery device according to 2.
4). 4. The organic solvent recovery device according to any one of 1 to 3, wherein the organic solvent contained in the gas to be treated is a ketone-based or diene-based organic solvent.

  By using the organic solvent recovery device of the present invention, by cooling the tank drain pipe connected to the lower part of the adsorption tank when treating a highly reactive organic solvent, the bumping of the condensate is suppressed and the adsorbent is supplied to the adsorbent. By reducing adhesion, it can be processed safely.

1 shows an example of an organic solvent recovery device according to the present invention. An example at the time of installing the baffle 19 (adsorption tank lower part enlarged view) is shown. 1 shows an example of a general organic solvent recovery device. It is a measurement result of the temperature in the tank drain piping 17 in the adsorption / desorption process in Example 1. It is the measurement result of the temperature in the tank drain piping 17 in the adsorption / desorption process in the comparative example 1.

  The organic solvent recovery device of the present invention is configured to adsorb an organic solvent by bringing a gas to be treated containing the organic solvent into contact with each other and to adsorb an adsorbent that desorbs the adsorbed organic solvent by bringing into contact with water vapor. An adsorption step comprising an adsorption tank, supplying a gas to be treated to the adsorbent filled in the adsorption tank, adsorbing the organic solvent to the adsorbent and discharging it as a processing gas, and an adsorption filled in the adsorption tank A desorption gas containing the organic solvent discharged in the desorption step is alternately repeated by desorbing the organic solvent from the adsorbent by supplying water vapor to the material and discharging it as a desorption gas containing the organic solvent. An organic solvent recovery device that cools and collects water in a condenser, and cools a tank drain pipe connected to the lower part of the adsorption tank to discharge drain water condensed in the adsorption tank in the desorption step. It characterized by having a system that.

  In the system which cools the said tank drain piping, it is preferable to make a tank drain piping into a double pipe structure, and to introduce | transduce cooling water and cold water to the outer side of a double pipe. As the cooling water and cold water used here, the cooling water and cold water used in the condenser for condensing the organic solvent-containing water vapor generated during the regeneration of the organic solvent recovery apparatus may be reused. By reusing, the amount of cooling water and cold water used can be reduced.

  It is preferable that the temperature at which the tank drain pipe is cooled is equal to or lower than the azeotropic temperature of the organic solvent and water contained in the gas to be treated. By setting it as azeotropic temperature or less, the splash of the solvent from a tank drain piping can be suppressed significantly.

  Examples of the organic solvent contained in the gas to be treated preferably recovered by the organic solvent recovery apparatus of the present invention include ketone-based or diene-based organic solvents. The ketone-based or diene-based organic solvent is very reactive, and is an organic solvent that generates a peroxide in the reaction process and may burn when accumulated in a large amount in the adsorbent. In particular, when the liquid adheres to the adsorbent, a more remarkable reaction is exhibited. Therefore, by using the organic solvent recovery apparatus of the present invention, it becomes possible to safely treat highly reactive organic solvents such as ketone-based or diene-based organic solvents.

  A preferred embodiment of the present invention is illustrated in FIG. The organic solvent-containing treated gas 2 is sent to an adsorption tank 7 which is in an adsorption process by opening and closing automatic lower dampers 5 and 6 by a blower 3, and the organic solvent contained in the treated gas is an adsorbent in the adsorption tank 7. As a result, the gas to be treated becomes a treated gas, is sent to the exhaust port 9 and is released into the atmosphere.

  On the other hand, the adsorbent 8 on which the organic solvent in the adsorption tank 7, which is in the desorption process by automatically opening and closing the upper dampers 10 and 11, is desorbed by water vapor introduced from the water vapor line 12, and is condensed through the recovery line 13. The organic solvent which has been introduced into 15 and liquefied / condensed in the cooling water 16 and aggregated is recovered as the recovery solvent 14. Further, the water vapor containing the organic solvent condensed in the adsorption tank 7 is sent to the recovery solvent 14 through the tank drain pipe 17.

  When the drain water containing the organic solvent condensed in the adsorption tank 7 during the desorption process stays in the tank drain pipe 17 and bumps by the heat of water vapor, the organic solvent is introduced from the lower part of the adsorption tank 7. In order to prevent the mixed liquid of water and water from adhering to the adsorbent 8, a double pipe type cooler 18 is attached to the tank drain pipe 17 as shown in FIG. 1 and the cooling water 16 stays in the tank drain pipe 17. We have devised a system for cooling drain water containing organic solvents.

  Further, in order to prevent the organic solvent and water scattered from the lower part of the adsorption tank 7 from adhering to the adsorbent 8, a baffle 19 is provided at the outlet to the tank drain pipe 17 connected to the adsorption tank 7, as shown in FIG. Providing is also a preferred embodiment. By providing the baffle 19, it is possible to further prevent the organic solvent and water from scattering from the tank drain pipe 17, and the safety of the apparatus is further improved.

  The shape of the baffle 19 may be a flat plate shape, an umbrella shape, or a hemispherical shape, and is preferably a conical shape or a divergent shape with respect to the discharge port. The baffle 19 is installed by a support so as to be positioned above the discharge port. As the material of the baffle 19, it is preferable to use a material that does not dissolve in the organic solvent contained in the organic solvent-containing gas 2 to be treated.

  Hereinafter, the present invention will be described in more detail with reference to examples. Example 1 in which methyl ethyl ketone is treated using the apparatus of the present invention that cools the tank drain pipe connected to the lower part of the adsorption tank is referred to as Example 1, and an example in which methyl ethyl ketone is treated in a normal solvent recovery apparatus as Comparative Example 1. It is shown below.

[Example 1]
In the organic solvent recovery apparatus of the present invention shown in FIG. 1, the gas to be processed was normalized under the following conditions to recover the organic solvent. Note that the present invention is not limited to this.

As the organic solvent-containing gas to be treated 2, a 45 ° C. solvent mixed gas containing 4000 ppm of methyl ethyl ketone, which is a kind of ketone-based organic solvent, is sent to the adsorption tank 7 by the blower 3 at an air volume of 4.0 Nm ³ / min. For 10 minutes. After the adsorption treatment, desorption was performed with water vapor for 10 minutes. A mixed gas of methyl ethyl ketone and water vapor, which is a desorption gas, was sent to the condenser 15 and condensed in the cooling water 16 to recover methyl ethyl ketone. Here, in order to cool the drain water of methyl ethyl ketone discharged and retained from the adsorption tank 7 to the tank drain pipe 17 in the desorption process, the tank drain pipe 17 was cooled by the double pipe cooler 18. At that time, the temperature in the tank drain pipe 17 in a series of methyl ethyl ketone adsorption / desorption treatment was measured. The results are shown in FIG.

[Comparative Example 1]
In the general organic solvent recovery apparatus shown in FIG. 3, the gas to be processed was normalized under the following conditions, and the organic solvent was recovered.

As the organic solvent-containing gas to be treated 2, a 45 ° C. solvent mixed gas containing 4000 ppm of methyl ethyl ketone, which is a kind of ketone-based organic solvent, is sent to the adsorption tank 7 by the blower 3 at an air volume of 4.0 Nm ³ / min. For 10 minutes. After the adsorption treatment, desorption was performed with water vapor for 10 minutes. A mixed gas of methyl ethyl ketone and water vapor, which is a desorption gas, was sent to the condenser 15 and condensed in the cooling water 16 to recover methyl ethyl ketone. At that time, the temperature in the tank drain pipe 17 in a series of methyl ethyl ketone adsorption / desorption treatment was measured. The results are shown in FIG.

  As can be seen by comparing the graphs shown in FIGS. 4 and 5, by using the apparatus of the invention of Example 1, the temperature in the tank drain pipe 17 is 73 ° C. or lower, which is the azeotropic temperature of methyl ethyl ketone and water. It is clear that it is possible to suppress the sudden boiling of drain water containing methyl ethyl ketone in the tank drain pipe 17.

  The organic solvent recovery processing device includes the organic solvent in the tank drain pipe by cooling the tank drain pipe connected to the lower part of the adsorption tank when processing a gas to be processed containing a highly reactive organic solvent. It contributes to the industry because it can suppress the sudden boiling of drain water and process it more safely.

1. Organic solvent recovery device 2. Gas to be treated containing organic solvent Blower 4 Blower duct 5. Automatic lower damper 6. Automatic lower damper 7. Adsorption tank 8. Adsorbent 9. Exhaust port 10. Automatic upper damper 11. Automatic upper damper 12. Steam line 13. Collection line 14. Collected solvent 15. Condenser 16. Cooling water
17. Tank drain piping 18. Double tube cooler 19. Baffle

Claims (4)

It comprises a plurality of adsorption tanks filled with an adsorbent that adsorbs an organic solvent by contacting a gas to be treated containing an organic solvent, and desorbs the adsorbed organic solvent by contacting water vapor,
An adsorption step of adsorbing an organic solvent to the adsorbent by supplying a gas to be treated to the adsorbent filled in the adsorption tank and discharging it as a treatment gas;
A desorption step of desorbing the organic solvent from the adsorbent by supplying water vapor to the adsorbent filled in the adsorption tank and discharging it as a desorption gas containing the organic solvent;
Repeat alternately,
An organic solvent recovery device that cools and recovers a desorption gas containing an organic solvent discharged in a desorption process with a condenser,
An organic solvent recovery apparatus comprising a system for cooling a tank drain pipe connected to the lower part of the adsorption tank in order to discharge drain water condensed in the adsorption tank in the desorption step.   2. The organic solvent according to claim 1, wherein in the means for cooling the tank drain pipe, a temperature detector is installed in the tank drain pipe, and the condensate temperature in the tank drain is made equal to or lower than the azeotropic temperature of the organic solvent and water. Recovery device.   2. As a means for cooling the tank drain pipe, a double pipe type cooler is connected to the tank drain pipe, and the tank drain pipe is cooled by introducing cooling water and cold water into the double pipe type cooler. Or the organic-solvent collection apparatus of 2.   The organic solvent recovery apparatus according to any one of claims 1 to 3, wherein the organic solvent contained in the gas to be treated is a ketone-based or diene-based organic solvent.