JPS605205A - Solvent recovery apparatus - Google Patents

Abstract

PURPOSE:To attain to conserve energy, by evaporating water by utilizing the heat of condensation of used steam and solvent vapor while supplying the aforementioned steam to a steam generating means only after an initial stage for desorbing a solvent from an adsorbent is elapsed. CONSTITUTION:An adsorbent is charged in an adsorbing tank 21 while the solvent in a solvent atmosphere introduced into said tank 21 from a drying apparatus through an opening and closing valve 23 is adsorbed with the adsorbent 22 and air from which the solvent is removed is exhausted to the outside from an opening and closing valve 24. In this case, desorbing steam formed in a boiler 21 and a compresser 27 constituting a steam generating means is enabled to be supplied to the adsorbing tank 21 through an opening and closing valve 25. That is, after the solvent adsorbing process with the adsorbent 22 is completed and the opening and closing valves 23, 24 are closed, the opening and closing valve 25 is opened and the solvent adsorbed with the adsorbent 22 is desorbed by the desorbing steam at a predetermined temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solvent recovery device for recovering a solvent from a solvent atmosphere.

Generally, a solvent recovery device is used in an adhesive tape production line as shown in FIG. 1, for example.

That is, in this adhesive tape production line, rubber as an adhesive is applied to the surface of the tape 2 by the application roll 3 in a state in which a solvent is added in the sizing device 1 . The solvent applied to the surface of the tape 2 together with the rubber is then evaporated and removed from the surface of the tape 2 in the drying device 4.

In this way, the acidic atmosphere generated in the drying device 4 is
The solvent is sent to a solvent recovery device 5 shown in detail in the figure, and the solvent is adsorbed by an adsorbent 6A such as activated carbon in an adsorption tank 6. The air from which the solvent has been removed is discharged to the outside as shown by broken line arrows in FIGS. 1 and 2.

After the adsorption process is completed, the solvent adsorbed by the adsorbent is desorbed by desorption steam at a predetermined temperature generated in the boiler 7, and becomes solvent vapor. The spent steam used for this desorption and the desorbed solvent vapor are condensed in a boiler feed water heater 8 and a cooler 9, respectively, and then subjected to specific gravity separation in a solvent separation type 10, or in a distillation column 11. The solvent is separated by distillation, making it possible to recover the solvent.

Here, in the conventional solvent recovery device 5, as shown in the energy flow chart of FIG. Although a part of the condensation heat is reused as heating energy for boiler water in the boiler water heater 8, most of the condensation heat is released into the atmosphere from the cooling tower 12 connected to the cooler 9. Note that, as shown in FIG. 3, part of the energy that the boiler 7 gives to the adsorption tank 6 is consumed by increasing the temperature of the adsorption tank 6 and releasing heat to the atmosphere.

That is, the conventional solvent recovery apparatus has a problem in that the reuse rate of the heat of condensation of used steam and solvent vapor is low.

In addition, in the solvent desorption process in the solvent recovery device 5, the mixed concentration of the desorbed solvent vapor with respect to the used water vapor subjected to desorption changes with the passage of time after desorption, and the mixed vapor The vapor temperature and condensation temperature of will increase with time after desorption. Therefore, when attempting to reuse the condensation heat of spent steam and solvent vapor in a solvent recovery device, the energy fluctuations of the spent steam and solvent vapor may lead to instability in the operability of the scraping recovery process. An unprecedented assignment is necessary.

An object of the present invention is to provide a solvent recovery device that can save energy by effectively reusing the heat of condensation of spent steam and solvent vapor while ensuring stable operation of the solvent recovery process. shall be.

In order to achieve the above object, the solvent recovery device according to the present invention includes a steam generating means for evaporating water by using the heat of condensation of used steam and solvent vapor to obtain desorption steam at a predetermined temperature, and an adsorption device. and switching means for supplying the used steam and solvent vapor to the steam generating means only after the initial stage of the desorption process in which the solvent is desorbed from the solvent.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 4, the adsorption tank 21 contains an adsorbent 22 such as activated carbon, and absorbs the solvent in the solvent atmosphere introduced from the drying device 4 shown in FIG. 2
The air from which the solvent has been removed can be discharged to the outside from an on-off valve 24.

In addition, for the adsorption@21, a predetermined temperature, for example 105° C., is generated in a boiler 26 and a compressor 27 constituting steam generating means, which will be described in detail later, via an on-off valve 25.
It is said that it is possible to supply water vapor for desorption. That is, the adsorption process of the solvent by the adsorbent 22 is completed, and the on-off valve 2
3.24 is closed, the on-off valve 25 is opened, and the solvent adsorbed on the adsorbent 22 is desorbed by the desorption water vapor at the predetermined temperature.

Here, the mixed concentration of the desorbed solvent vapor with respect to the used steam subjected to desorption decreases with the passage of time after desorption, and the vapor temperature and condensation temperature of the mixed vapor after desorption are It increases over time. Therefore, at the initial stage of the desorption process in which the solvent is desorbed from the adsorbent 22,
A compressor 2 in which the steam temperature and condensation temperature of used steam and solvent vapor are relatively low and constitutes a steam generating means to be described later.
7, it is difficult to obtain desorption water vapor at a predetermined temperature.

Therefore, the adsorption tank 21 is equipped with switching valves 288 and 28B as switching means for switching the route of the condensation and reuse process of used steam and solvent vapor.

That is, at the initial stage of the desorption process in the adsorption tank 21, the switching valve 28A is opened and the switching valve 28A is opened.
After B is closed and the mixed vapor of spent steam and solvent vapor is condensed into water and solvent in the cooler 29, a solvent separator 10 similar to that shown in FIG. , water and solvent are separated, and the solvent can be recovered. Note that 30 is a cooling tower connected to the cooler 29.

Next, after the initial stage of the desorption process in the adsorption tank 21, when the vapor temperature and condensation temperature of the spent steam and solvent vapor reach a predetermined temperature, for example, 95°C, the switching valve 28A is closed and the switching valve 28A is closed. The valve 28B is opened, and the mixed vapor of used steam and solvent vapor is guided to the liquid film evaporator 31, where it is condensed into water and solvent. The water and solvent thus condensed are cooled in the boiler water heater 32 and the cooler 331, and then led to the solvent separator 1° or the distillation column where they are separated into water and bath agent.
It is assumed that the solvent can be recovered.

Here, the liquid film evaporator 31, together with the pump 34, the steam separator 35, and the compressor 27, constitutes water vapor generating means. That is, the pump 34 supplies, for example, water at about 90° C. as a liquid film flow to the inner surfaces of the evaporation tubes arranged in large numbers in the liquid film evaporator 31, and the liquid film evaporator 31 supplies the liquid film flow on the inner surfaces of the evaporation tubes. It is evaporated with a high heat transfer coefficient to obtain water vapor at, for example, about 90°C. The steam separator 35 separates the water vapor at about 90°C from water and supplies it to the compressor 27. The compressor 27 compresses the water vapor to obtain desorption water vapor at a predetermined temperature, for example, 105°C. possible. This desorption steam is
As described above, the solvent supplied to the adsorption tank 21 and adsorbed on the adsorbent 22 can be desorbed. In addition, the steam separator 3
5 can be replenished with boiler water in order to compensate for the amount of water vapor flowing out to the compressor 27 and adsorption tank 21 side.

According to the above example, as shown in the energy MfC curve in Figure 5, most of the heat of condensation of the spent steam used to desorb the solvent from the adsorbent 22 and the desorbed solvent vapor is absorbed into the liquid. By recovering the water vapor in the membrane evaporator 31 and replenishing it with a small amount of energy of about a few percent in the compressor 27, it becomes possible to obtain most of the desorption water vapor, making it possible to achieve a large energy saving.

In addition, a liquid film evaporator 31 is used as a part of the water vapor generating means.
As a result, the heat transfer coefficient becomes large and it becomes possible to downsize the device. Furthermore, since heat is exchanged using the latent heat of vaporization, the capacity of the pump 34 can be made smaller than when heat is exchanged using the sensible heat of water.

Further, the used steam and solvent vapor are not supplied to the steam generating means at the initial stage of the desorption process.

It is supplied to the steam generating means only after the initial stage has passed. Therefore, the steam generating means always generates the action of the spent steam and solvent vapor having a high steam temperature and a high condensation temperature after the above-mentioned initial stage has passed from one of the plurality of adsorption tanks 21 arranged in parallel with each other. and a predetermined temperature, for example 105
It is possible to continuously obtain water vapor for desorption at a temperature of 0.degree. C., and it is possible to ensure stable operation of the solvent recovery process.

Note that in the above embodiment, the case where the liquid film evaporator 31 is used as a part of the water vapor generating means has been described. However, in the steam generating means of the present invention, instead of the liquid film evaporator 31, another type of evaporator is used, such as a combination of a heater that exchanges heat using sensible heat of water and an evaporator consisting of a flash tank. It may be something.

As described above, the solvent recovery device according to the present invention evaporates water by utilizing the heat of condensation of used steam and solvent vapor, and includes a steam generating means for obtaining desorption steam at a predetermined temperature, and The switching means is provided for supplying the used steam and solvent vapor to the steam generating means only after the initial stage of the desorption process in which the solvent is desorbed. Therefore, while ensuring stable operability of the solvent recovery process, it is possible to save energy by effectively reusing the heat of condensation of the spent steam and solvent vapor.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a general adhesive tape manufacturing line, Fig. 2 is a system diagram showing a conventional solvent recovery device, Fig. 3 is an energy flow diagram of a conventional solvent recovery device, and Fig. 4 is a system diagram showing a conventional adhesive tape production line.
The figure is a system diagram showing a solvent recovery device according to an embodiment of the present invention, and FIG. 5 is an energy flow chart of the solvent recovery device according to the same embodiment. DESCRIPTION OF SYMBOLS 10...Solvent separator, 21...Adsorption tank, 22...Adsorbent, 27...Compressor, 28A, 28B・Switching valve, 3
1...Liquid film evaporator, 34.Pump, 35...Steam water separator.

Claims (1)

[Claims] (1) The solvent in the solvent atmosphere is adsorbed on an adsorbent, the solvent adsorbed on the adsorbent is desorbed by desorption steam at a predetermined temperature, and the spent steam subjected to the desorption and the desorbed solvent vapor In a solvent recovery device that recovers a solvent from a solvent atmosphere by condensing water and separating the condensed water and solvent from each other, the heat of condensation of the spent steam and solvent vapor is utilized to evaporate water and maintain the temperature at a predetermined temperature. and a switching means for supplying spent steam and solvent vapor to the steam generating means only after the initial stage of the desorption process of desorbing the solvent from the adsorbent. Solvent recovery device d characterized by