JPH0466605B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a continuous circulation type adsorption/desorption method with high recovery efficiency of organic solvents, etc., and in particular, to a desorption method of a primary organic solvent adsorption/desorption device that performs continuous adsorption. The non-condensed exhaust air from the condensing device installed in the exhaust line is guided to a separately installed secondary organic solvent adsorption/desorption device to reduce the release of organic components as much as possible, and the desorption exhaust from the secondary organic solvent adsorption/desorption device is The present invention relates to a continuous circulation type adsorption/desorption method in which the non-condensable gas is recirculated to a primary organic solvent adsorption/desorption device after being condensed, thereby performing efficient organic solvent adsorption/desorption using a small amount of equipment.

[Prior Art] The basic structure of a means for treating vaporized organic solvents with an adsorbent or the like for the purpose of recovering vaporized organic solvents or removing harmful components in the air is shown conceptually in Figure 1. I can do it. That is, adsorption tanks 1 and 2 filled with an adsorbent such as powdered activated carbon are placed next to each other as shown in the figure, and are connected by crossed piping as shown in the figure, so that adsorption and desorption are alternately repeated. Therefore, if the valves 3 and 4 are closed and the valves 5 and 6 are opened, the gas to be treated G flows in the directions of arrows A, A', and A'', and adsorption is performed in the adsorption tank 1. If the valves 7 and 8 are closed on the 2nd side and the valves 9 and 10 are opened, the desorption gas (usually steam) S flows in the directions of arrows B, B', and B'' to perform desorption. This desorbed gas is then sent to a processing device, for example a condensing device 11, where organic solvents and the like are condensed. Further, after a certain period of time has elapsed, the opening and closing of the valves are all reversed, and desorption is performed on the adsorption tank 1 side and adsorption is performed on the adsorption tank 2 side.

However, the above method has the following drawbacks. That is, as is clear from the figure, it is necessary to provide a large number of valves, which not only complicates the structure and operation of the device, but also prevents malfunctions or breakdowns even though valve 3 and valve 10 are not open. When the desorption gas is blown into the adsorption tanks 1 and 2, the interiors of the adsorption tanks 1 and 2 become overpressured, exposing them to dangers such as explosion.

Therefore, it is desired to solve the above-mentioned drawbacks, and the present applicant has proposed a continuous organic solvent adsorption/desorption device as shown in FIG. 2 (Japanese Patent Publication No. 54-30917). This device 12
includes a distribution chamber 13, adsorption chambers 14 and 15, and a gathering chamber 1.
6 is defined, and adsorbents 26 and 27 made of activated carbon fiber or the like are arranged in the adsorption chambers 14 and 15. In addition, desorption gas exhaust pipes 17, 17a are provided at the inlets 19, 20 and outlets 21, 22 of each adsorption chamber 14, 15.
and desorption gas introduction pipes 18, 18a are provided, which are movable in the vertical direction of the drawing by an operating air cylinder 23. And in the figure, the discharge pipe 17
Since the introduction pipe 18 is in pressure contact with the adsorption chamber 14, the desorption gas S is transferred from the flexible hose to the adsorption chamber 14.
The gas to be treated G enters the inlet 2 and is desorbed.
After entering the adsorption chamber 15 from 0 and being adsorbed, it is released from the outlet 22. Therefore, in the case of this apparatus, even if the desorption gas exhaust pipe or desorption gas introduction pipe is incorrectly connected, there is no risk of overpressure inside the apparatus as described above, and there is no risk of explosion. However, as the research progressed further, it was discovered that the devices shown in Figures 1 and 2 had a common drawback. That is, the recovery of the desorption solvent in the condensing device 11 is performed by cooling and condensing the vaporized solvent diffused in the steam. Cooling does not result in sufficient condensation, and a considerable amount of the solvent remains uncondensed and is discharged in the direction of arrow S'. Also, when the solvent concentration is dilute, condensation tends to be insufficient, and the amount released also increases. Therefore, in each of the above-mentioned apparatuses, the recovery rate is poor when low boiling point organic solvents or low concentration organic solvents are to be recovered, and there remains room for improving the recovery rate, in other words, the removal rate of harmful components. In particular, when a gas mixed with a low concentration of a low boiling point organic solvent is to be treated, condensation and separation tend to be insufficient, and the above-mentioned tendency is strong.

[Problems to be Solved by the Invention] The present invention has been made in view of these circumstances, and although it is capable of continuously processing gas containing an organic solvent, it is capable of treating a gas containing an organic solvent using a device with a simple structure. This was done with the aim of providing a method for increasing the recovery rate of.

[Means for Solving the Problems] The present invention, which has achieved the above object, is a primary organic solvent adsorption/desorption device equipped with a plurality of adsorption chambers, and continuous adsorption by switching adsorption in each adsorption chamber at set time intervals. Each adsorption chamber is completed and desorbed in a time shorter than the set adsorption time, and the desorption exhaust gas from this primary adsorption/desorption device through the condensing device is transferred to the secondary organic solvent adsorption device connected to the condensing device. Water vapor for desorption is introduced into the secondary adsorption/desorption device during the intermittent adsorption of the secondary organic solvent adsorption/desorption device, and this desorption exhaust gas is transferred to the desorption device. The gist is to supply the gas to a condensing device for processing, and to flow the exhaust gas from the secondary adsorption/desorption device through the condensation device into the processing gas introduction section of the primary adsorption/desorption device.

[Operations and Examples] Hereinafter, typical examples of the present invention will be described based on the drawings. However, the following examples are representative examples and do not limit the present invention, and are compatible with the spirit of the above and below. It is also possible to carry out the invention with appropriate changes within the scope possible, and all of these are included within the technical scope of the present invention.

FIG. 3 is a flow diagram showing an example of continuous circulation adsorption/desorption of an organic solvent. The adsorption/desorption device consists of a primary organic solvent adsorption/desorption device (for dilute gas) 12, a condensation device 11, a secondary organic solvent adsorption/desorption device (for condensed gas) 29, and piping and switching means connecting these. Since the structure of the adsorption/desorption device 12 is essentially the same as that shown in FIG. 2, the details are omitted in FIG.
However, the structure of the adsorption/desorption device itself does not limit the present invention.

The operating method shown in FIG. 3 using the adsorption/desorption device shown in FIG. 2 is as follows. Although it varies depending on the type of gas to be treated and the adsorption capacity, in general, after the adsorption operation in either adsorption chamber 14 or 15 continues for 10 minutes, the exhaust pipe and the inlet pipe are switched to desorb the adsorption chamber. The cycle is often repeated in which the operation is performed for 3 minutes, followed by a 7-minute pause period until the adsorption time (10 minutes) in the other side of the adsorption chamber has elapsed, and then the adsorption operation starts again. The following will focus on the operating method under such conditions.

When treating low-boiling point solvents such as those mentioned above, since a large amount of organic solvents are present in the exhaust gas from the condensing device, the present invention is designed to transfer the organic solvents to a secondary adsorption/desorption device via a pipe. It will be introduced on 29th. The secondary adsorption/desorption device 29 is smaller due to its smaller processing capacity, but since exhaust gas containing a fairly high concentration of organic solvent is introduced, low boiling point organic solvents can be absorbed in the same way as the primary adsorption/desorption device. Adsorbed efficiently. As shown in Fig. 4, the gas discharge from the condensing device 11 is completed in 3 minutes for the reason mentioned above, but the adsorption in the secondary adsorption/desorption device 29 is also completed in 3 minutes, and thereafter, during the rest period. No desorption gas is discharged from the primary adsorption/desorption device for a certain 7 minutes. That is, unlike the primary adsorption/desorption device, the secondary adsorption/desorption device performs adsorption and desorption alternately and intermittently, so it can be operated continuously with a single adsorption chamber. That is, during the pause period after the adsorption operation is completed, water vapor S'' is introduced into the secondary adsorption/desorption device 29 from the opposite direction,
The adsorbed organic solvent is desorbed, and the discharged steam containing a high concentration of organic solvent is introduced into the condensing device 11 via the pipe 31, where the organic solvent is efficiently recovered. However, this exhaust gas from the condensing device 11 still contains some organic solvent, so in order to prevent the organic solvent in the exhaust gas from being discharged outside the system, the exhaust gas is transferred to the primary adsorption/desorption device 12 to be treated. The gas is introduced into the gas introduction pipe 32, merged with the gas to be treated that is being sent into the adsorption chamber 14 or 15, and subjected to the adsorption/desorption cycle again.

FIG. 4 shows the above operation in terms of time schedule. When 10 minutes of adsorption in the adsorption chamber 14 is completed and the adsorption chamber 15 is switched to adsorption and the adsorption chamber 14 is switched to desorption, there is a very small time difference. Condensation in the condensing device 11 and secondary adsorption/desorption device 29
After 3 minutes have elapsed, desorption in the secondary adsorption/desorption device 29 and condensation in the condensing device 11 are performed for 3 minutes, and the exhaust gas from the condensing device 11 is subjected to adsorption in the adsorption chamber 15. Ru. Therefore, even after the adsorption and desorption by the secondary adsorption/desorption device 29 is completed, only 6 minutes are spent during this period, and adsorption in the adsorption chamber 15 continues for another 4 minutes. Therefore, the adsorbent that has been warmed during desorption in the adsorption chamber 14 is sufficiently cooled down during the 7-minute pause period and is ready for the next adsorption.

In Fig. 3, the adsorption chambers in the primary adsorption/desorption device are explained as two, but if necessary, the number of adsorption chambers can be increased to three or more. As a preferred example, it is also recommended that the adsorbent heated by steam be sufficiently cooled.

[Effects of the Invention] Since the present invention is configured as outlined above,
Although continuous adsorption is performed by the primary organic solvent adsorption/desorption device, organic solvents that were previously discharged without being completely liquefied in the condensing device are now transferred to the secondary adsorption/desorption device without escaping out of the system. Not only can it be adsorbed, but it can also be recovered by desorption using the secondary desorption device, and the non-condensed content at this time can be returned to the primary adsorption and desorption device for cyclic adsorption.
In addition, since one condensation device is sufficient, simply adding a secondary adsorption/desorption device improves the recovery efficiency of organic solvents and almost eliminates their release into the atmosphere, contributing to the prevention of air pollution. is also extremely large.

[Brief explanation of the drawing]

Fig. 1 is a flow diagram of a valve switching type organic solvent adsorption/desorption device used in a conventional method, Fig. 2 is a schematic explanatory diagram of a conventional continuous organic solvent adsorption/desorption device, and Fig. 3 is a continuous flow diagram of a conventional continuous organic solvent adsorption/desorption device. FIG. 4 is a flowchart explaining the circulation type adsorption/desorption method, and FIG. 4 is a graph explaining the operation schedule of the flow shown in FIG. 1, 2...Adsorption tank, 3-10...Valve, 11...
Condensation device, 12...Primary adsorption/desorption device, 13...Distribution chamber, 14, 15...Adsorption chamber, 16...Collection chamber,
17...Introduction pipe, 18...Discharge pipe, 23...Air cylinder, 26, 27...Adsorption material, 29...Secondary adsorption/desorption device.

Claims (1)

[Scope of Claims] 1. When adsorbing and desorbing a processing gas containing an organic solvent using a primary organic solvent adsorption/desorption device equipped with a plurality of adsorption chambers, each adsorption chamber is used alternately at each set time. In addition to switching to perform continuous adsorption,
In a continuous circulation adsorption/desorption method for organic solvents in which the desorbed exhaust gas in the adsorption chamber is treated by a condensing device connected to the primary adsorption/desorption device, each adsorption chamber is intermittently operated at a time shorter than the adsorption set time. Desorption is carried out, and the desorbed exhaust gas from the primary adsorption/desorption device through the condensation device is sent to the secondary organic solvent adsorption/desorption device connected to the condensation device to perform intermittent adsorption; During intermittent adsorption of the adsorption/desorption device, water vapor for desorption is introduced into the secondary adsorption/desorption device, this desorption exhaust gas is sent to the condensing device for processing, and further, the secondary adsorption/desorption device side A continuous circulation type adsorption/desorption method for organic solvents, characterized in that the desorption exhaust gas that has passed through the condensing device is merged into the processing gas introduction section of the primary adsorption/desorption device.