JPH0624606B2 - Solvent vapor recovery device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solvent vapor recovery apparatus, and more particularly to a solvent vapor recovery apparatus that combines a regenerator and an activated carbon adsorption tower.

2. Description of the Related Art Conventionally, in this type of device, a regenerator is provided in the front stage and an activated carbon adsorption tower is provided in the rear stage, and they are operated as separate devices. That is, in the former regenerator, the solvent vapor in the gas is cooled to the surface temperature of the regenerator material in the regenerator, and the solvent vapor is condensed to the equilibrium concentration at that temperature. However, the equilibrium concentration is sent to the activated carbon adsorption tower while remaining in the gas. The remaining solvent vapor is adsorbed on the activated carbon and almost removed. Although the temperature of the gas leaving the regenerator is low, the temperature of the activated carbon adsorption tower hardly changes due to the heat generated during adsorption. Therefore, the adsorption characteristic of the solvent by the activated carbon is governed by the adsorption temperature line at room temperature. As the adsorption of the solvent progresses, the activated carbon reaches saturation, the adsorption capacity of the activated carbon decreases, and regeneration is required.

Regeneration of activated carbon according to the prior art is performed by a thermal desorption operation using steam. That is, when the activated carbon is heated, the adsorbed solvent is desorbed while the concentration of the solvent vapor in the gas and the adsorption amount of the activated carbon maintain an equilibrium relationship at that temperature. When fully desorbed, the activated carbon is regenerated. The desorbed solvent vapor is a mixed gas with steam, but it is cooled by cooling water with a condenser,
Condenses into solvent. Water generated by condensation of the solvent and steam is separated by a gravity separator, and the solvent is recovered. On the other hand, water is discharged as drain water.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned conventional technique, the fluorocarbon 1 used for cleaning or the like is used.
In the case of solvent such as 13, etc., 120 ℃ at the time of desorption of activated carbon
It has to be heated to a certain degree, and there are drawbacks such as the use of a large amount of steam and the large latent heat of steam contained in the condensation of the desorption gas, and the use of a large amount of cooling water.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a solvent vapor recovery apparatus that combines a regenerator and an activated carbon adsorption tower without using a large amount of steam and cooling water.

Means for Solving the Problems In the present invention, when solvent vapor is adsorbed on and recovered by activated carbon, if the temperature at the time of adsorption is lowered, the desorption performance is large even if the desorption temperature by heating is relatively low. It was made paying attention to that it does not decrease. Then, as means for lowering the adsorption temperature, cooling of the target gas by the regenerator and cooling by the heat transfer tube installed in the activated carbon adsorption tower are used, and the refrigerant pressurized by the compressor is condensed by the condenser to regenerator and activated carbon adsorption tower. The above problem is solved by directly supplying the hot gas of the refrigerant which is supplied to the activated carbon adsorption tower to the activated carbon adsorption tower so that it can be heated. These pipes were connected by valve operation for each operation of adsorption, desorption and cold storage.

That is, in the solvent vapor recovery apparatus according to the present invention, a regenerator having a heat transfer tube and an activated carbon adsorption tower provided with a heat transfer tube inside are connected by a pipe, and the heat transfer tubes of the regenerator and the activated carbon adsorption tower are connected to a refrigerant compressor to a valve. The refrigerant is supplied via the expansion valve and the condenser via the heat transfer tube of the activated carbon adsorption tower, and further, a pipe for directly supplying the hot refrigerant hot gas from the compressor is attached, and further, from the activated carbon adsorption tower. The outflow pipe and the inflow pipe to the regenerator are connected by a desorption gas circulation pipe.

Action The heat transfer tube for activated carbon provided in the activated carbon adsorption tower cools the activated carbon with a refrigerant during adsorption to lower the adsorption temperature. Since the adsorption is performed at a low temperature, desorption by heating is also possible at a low temperature. The refrigerant pressurized by the compressor is condensed by the condenser and supplied to the regenerator and the heat transfer tubes in the activated carbon adsorption tower to cool the regenerator material and the activated carbon, and the hot gas of the refrigerant heats and desorbs the activated carbon.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a flow sheet showing one embodiment of the solvent vapor recovery apparatus according to the present invention.

The apparatus shown in FIG. 1 is installed to collect the solvent vapor in the exhaust gas discharged from the cleaning apparatus using Freon 113 as a solvent. The activated carbon adsorption tower 1, the regenerator 2, the compressor 3, It is composed of a condenser 4, a fan 5, a solvent recovery tank 6 and a piping system connecting these.

The cleaning device 21 includes a valve 11, a fan 5, and an inflow pipe 2.
It is connected to the regenerator 2 via 2, and the regenerator 2 is connected to the pipe 2
3 is connected to the activated carbon adsorption tower 1 and communicates with the outside air via a valve 12. Further, the desorption gas circulation pipe 24 is branched between the activated carbon adsorption tower 1 and the valve 12, and the fan 2
0 and the valve 17 are connected to the inflow pipe 22 to the regenerator 2.

Inside the activated carbon adsorption tower 1, a heat transfer tube 7 for activated carbon is installed, and an activated carbon 8 is filled between the heat transfer tubes 7. Further, a heat transfer tube 9 for regenerator material is installed inside the regenerator 2, and a regenerator material 10 is filled between the heat transfer tubes 9.

Refrigerant is supplied from the compressor 3 to the heat transfer tube for activated carbon 7 through the valve 13, the condenser 4, the valve 19 and the valve 14, and from the compressor 3 in the regeneration cycle of the activated carbon adsorption tower. Valve 1
The hot gas can be supplied via No. 6.

On the other hand, valves 14 and 19 are provided for the heat transfer tube 9 for the cold storage material.
The refrigerant is supplied through a valve 15 from a branch pipe obtained by branching the refrigerant pipe.

Refrigerant and / or in heat transfer tube 7 for activated carbon and heat transfer tube 9 for regenerator material
Alternatively, the hot gas is returned to the suction side of the compressor 3.

Next, the operation of the apparatus shown in FIG. 1 will be described. In the cleaning device 21, the cleaning of the object to be cleaned is performed in the steps of charging, spraying, drying and taking out. In the spraying process, the CFC 113 of the solvent is vaporized, so that the cleaning device 2
The internal pressure of 1 rises. At this time, since the internal pressure rises, the pressure control device 18 is activated, the valve 11 is opened and the fan 5 is activated, and the gas containing 20 to 30% by volume of the steam of the flon 113 in the cleaning device 21 is introduced into the inflow pipe. First, it is sent to the regenerator 2 from 22.

The regenerator material 10 in the regenerator 2 is -2 by the low-temperature refrigerant supplied from the compressor 3 to the regenerator material heat transfer pipe 9 via the valve 13, the condenser 4, the expansion valve 19 and the valve 15.
Cool to 0 ° C. Therefore, the gas is cooled in the regenerator 2, and the chlorofluorocarbon contained in the gas is condensed until the gas concentration becomes about 5% by volume. The condensed chlorofluorocarbon is introduced into the solvent recovery tank 6 and stored.

Further, the gas in the regenerator 2 is supplied to the activated carbon adsorption tower 1 through the pipe 23. The activated carbon 8 in the activated carbon adsorption tower 1 includes the compressor 3, the valve 13, the condenser 4, and the expansion valve 1.
It is cooled to −20 ° C. by the low-temperature refrigerant supplied to the activated carbon heat transfer tube 7 via 9 and the valve 14. Here, the vapor of the Freon 113 in the gas is activated carbon 8 at -20 ° C.
And is adsorbed by the pores of the activated carbon 8. The amount of Freon adsorbed on the activated carbon at this time is governed by the temperature and the concentration of Freon gas in the gas, and follows the adsorption isotherm as shown in Fig. 2, that is, at -20 ° C, it is the same as at room temperature of 20 ° C. The equilibrium amount of activated carbon freon adsorption at the gas concentration is high, and many freon can be adsorbed.
The gas from which the CFC has been adsorbed and removed by the activated carbon adsorption tower 1 is released to the outside air through the valve 12.

Freon vapor generated during cleaning due to such operation is
It is recovered in the activated carbon adsorption tower 1. However, if the number of washings increases and the amount of CFC adsorption on activated carbon increases, the CFC adsorption capacity of activated carbon disappears. Therefore, regeneration by desorption of activated carbon is required.

The desorption operation is performed as follows.

First, the valves 11 and 12 are closed, the valve 17 is opened, the fan 20 is started, and the gas slowly circulates in the system. At the same time as the adsorption, a low temperature refrigerant is supplied to the regenerator 2, and the regenerator material 10 is maintained at a low temperature. On the other hand, with respect to the activated carbon adsorption tower 1, the refrigerant discharged from the compressor 3 is supplied as hot gas to the activated carbon heat transfer tube 7 as a heating gas through the valve 16 to gradually heat the activated carbon 8 to adsorb the flon. Desorption. By such an operation, the temperature of the activated carbon 8 rises to about 60 ° C., and the cool storage material 10 reaches −20 ° C. in the lowest temperature part. Therefore, the CFC concentration of the circulating gas at the inlet of the activated carbon adsorption tower 1 becomes an equilibrium concentration of about 5% by volume at the temperature of the regenerator material −20 ° C., and the activated carbon 8
The CFC adsorption amount of 0 is desorbed to the adsorption amount equilibrium with the gas concentration of 5% by volume in the adsorption isotherm at 60 ° C. shown in FIG. The desorbed CFC vapor is condensed in the regenerator 2 until it reaches the above concentration, and is recovered in the solvent recovery tank 6.

When the desorption is sufficiently carried out, the valve 16 is closed, the adsorption of the hot gas to the activated carbon adsorption tower 1 is stopped, the cooled refrigerant is supplied instead, and the temperature of the activated carbon 8 is lowered.
When the temperature of the activated carbon 8 is lowered, the residual CFC vapor in the circulating gas is adsorbed by the activated carbon 8 again, the gas concentration is lowered, and the desorption operation is completed after reaching a concentration that can be released to the outside of the system. In this way, the vapor of the solvent (CFC) in the gas discharged from the cleaning device can be recovered.

EFFECT OF THE INVENTION According to the solvent recovery apparatus of the present invention, the hot gas of the refrigerant is used for heating the activated carbon when the activated carbon is regenerated.
No steam or cooling water is required and significant energy savings are achieved.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an embodiment of the solvent recovery device of the present invention, and FIG. 2 is an adsorption isotherm diagram of chlorofluorocarbon of activated carbon. 1 ... Activated carbon adsorption tower, 2 ... Regenerator, 3 ... Compressor, 4 ... Condenser, 6 ... Solvent recovery tank, 7 ... Heat transfer tube for activated carbon, 9 ... Heat transfer tube for cold storage material

Claims (1)

[Claims] 1. A solvent vapor recovery apparatus in which a vaporized solvent is partially condensed and recovered through a regenerator, and the remaining solvent is further recovered by an activated carbon adsorption tower, in a regenerator having an electric heating tube and a heat transfer tube inside. The activated carbon adsorption tower provided with is connected by a pipe, to the heat transfer tubes of the regenerator and the activated carbon adsorption tower, the refrigerant is supplied from the refrigerant compressor through the valve through the expansion valve and the condenser, and to the heat transfer tube of the activated carbon adsorption tower. Further, a pipe for supplying high-temperature refrigerant hot gas directly from the compressor is provided, and the outflow pipe from the activated carbon adsorption tower and the inflow pipe to the regenerator are connected by a desorption gas circulation pipe. A solvent vapor recovery device characterized by the above.