JPH03188916A - Solvent recovery device - Google Patents

Abstract

PURPOSE:To improve the condensation efficiency of solvent and to carry out the concn. process by an adsorption tower with high efficiency by cooling and condensing the solvent containing gas in the dried state dehumidified with a dehumidifying means after the solvent contg. gas is concentrated through the adsorption tower. CONSTITUTION:The solvent adsorption body consisting of monolithically formed adsorption material the main component of which is an activated carbon and of the heat supply member brought into contact with the adsorption material is packed in plural adsorption towers 1, 2. The blower means 22, 23 of the solvent containing gas selectively flow the solvent contg. gas to be treated through the adsorption towers 1, 2 to obtain clean gas. The gas discharged from the adsorption tower 1, 2, is dehumidified by dehumidifying means 10, 11. The discharged gas dehumidified by the dehumidifying means 10, 11 is introduced into a condensation cooler 7 to be cooled to condense the solvent in the discharged gas. As a result, the condensation efficiency of solvent is improved, and the concn. process through the adsorption tower is carried out with high efficiency, and the required amount of adsorption material and the equipment cost are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a batch-type solvent recovery device for recovering a solvent from a process gas containing a solvent such as fluorocarbons, and in particular, a method for recovering a solvent without using water vapor during regeneration. It is related to the device.

[Prior Art] Recently, there has been an increased interest in environmental pollution, and regulations have been tightened from the standpoint of environmental conservation, and there is a tendency to prohibit the release of carbon waste into the atmosphere. In particular, air pollution caused by fluorocarbon gases containing chlorine is attracting attention as a serious problem on a global scale, and for this reason, regulations on the emission of fluorocarbon gases are being implemented.

Although these fluorocarbon gas emission regulations call for the complete discontinuation of the use of fluorocarbon gas in the future, during the current period until a replacement product is developed, fluorocarbon gas, which was previously released into the atmosphere, will be converted to lh. The next best option is to collect and reuse the waste to prevent it from being emitted. For this reason, various fluorocarbon gas recovery devices have been developed.

In conventional batch-type fluorocarbon gas recovery equipment, fluorocarbon-containing gas is selectively and alternately passed through multiple adsorption towers storing adsorbent material, and the fluorocarbons are adsorbed by the adsorbent material in the adsorption towers. clean gas is obtained. After adsorbing fluorocarbons, high-temperature steam is passed through the adsorbent in the adsorption tower, and the adsorbent is heated by this steam.
The adsorbent is regenerated by desorbing fluorocarbons from the adsorbent. In this way, by alternately repeating adsorption and desorption in a plurality of adsorption towers, fluorocarbons are removed from fluorocarbon-containing air and clean air is obtained. If necessary, a cooling gas at room temperature or other low temperature is passed through the adsorption tower after the desorption process to cool the adsorbent and increase its adsorption efficiency before moving on to the adsorption process. There is.

However, such conventional fluorocarbon gas recovery apparatuses have a drawback in that, because water vapor is used to regenerate the adsorbent, it is difficult to avoid the decomposition of fluorocarbons, that is, the generation of acids. That is, when fluorocarbons remain adsorbed on activated carbon for a long time under conditions where they are exposed to water vapor, a portion of the fluorocarbons decomposes, generating hydrochloric acid and hydrofluoric acid. This causes problems such as a decrease in the purity of fluorocarbons in the recovered fluorocarbons and the mixing of acids into waste water and purified gas. Also,
When recovering azeotropic CFCs containing alcohol, the alcohol dissolves in water and most of it is discharged along with the large amount of wastewater.
There are also problems such as the need to take measures against OD and COD.

Therefore, the present inventor proposed a solvent recovery device that does not use water vapor to regenerate the adsorbent (Japanese Patent Application No. 1-144987). This solvent recovery device is designed to heat the adsorbent with a sheet heater, and an example thereof is shown in FIG. That is, adsorbents 40 shown in FIG. 3 are housed in the two adsorption towers 1 and 2.

This adsorbent 40 has a sheet heater 42 interposed between a plurality of activated carbon adsorbents 41. and,
By energizing this seat heater 42, it generates resistance heat, thereby causing the adsorbent 41 in contact with the seat heater 42 to
It is designed to heat up. By stopping the power supply to the seat heater 42, the adsorbent 41 is allowed to cool.

Freon-containing air is supplied to the processing blower 3 via piping 21. The processing blower 3 is connected to a cooler 4 via a pipe 22, and the cooler 4 connects the first and second adsorption towers 1, 1, 2, 3, 3, 4, 3, 3, 3, 4 to 4 using a pipe 23 and pipes 23a, 23b branched from this pipe 23, respectively. It is connected to 2. Freon-containing air is transferred to piping 22, 23.23a by processing blower 3.
, 23b to the first and second adsorption towers 1 and 2. Cooling water is supplied to the cooler 4 to pre-cool the fluorocarbon-containing air sent into the adsorption tower 1.2. Note that on-off valves vI and V3 are interposed in the pipes 23a and 23b, respectively.

The purified air discharged from the first and second adsorption towers 1 and 2 is discharged into the atmosphere via pipes 24a and 24b and a main pipe 24 to which these pipes 24a and 24b are connected.

The pipes 24a and 24b each have on-off valves V2. V4 is installed.

In addition, the piping 24 includes the piping 2B'a, 27a and the piping 26b,
27b to one end of each of the first and second adsorption towers 1 and 2, respectively. Each of the pipes 26a and 28b has an atmosphere release valve v6. V8 is interposed, and piping 27
A and 27b each have a carrier air flow rate regulating valve VIOI.
V12 is installed. The other ends of the first and second adsorption towers 1 and 2 are provided with pipes 25a and 25b, respectively.
and piping 28a, 28b are connected. Piping 25a
.

25b joins the pipe 25, and this pipe 25 is connected to the pipe 22. Then, the pipe 25 has a pipe 25
A cooling blower 5 is interposed to suck air from the adsorption towers 1 and 2 through channels 25a and 25b, and on-off valves V5. V7 is installed.

Furthermore, the pipes 28a and 28b merge into a pipe 28, and are connected to the separator 8 via this pipe 28.

A vacuum pump 6 and a cooler 7 are interposed in this pipe 28, and the air inside the adsorption towers 1 and 2 is sucked by the vacuum pump 6 through the pipes 28a, 28b, and 28, and the air inside the adsorption towers 1 and 2 is sucked into the cooler 7. After cooling this suction air, it is sent to the separator 8.

Chill cooling water is supplied to the cooler 7, and the air containing fluorocarbons in the adsorption towers 1 and 2 sucked by the vacuum pump 6 is cooled by this chill cooling water, and the fluorocarbons and water in the air containing fluorocarbons are condensed. , these fluorocarbon liquids and water are supplied to the separator 8 together with air containing uncondensed fluorocarbons.

In the separator 8, water and fluorocarbon liquid are separated, and the fluorocarbon liquid is collected in a tank 9 for recovery.

Moisture is discharged from separator 8. On the other hand, the air containing uncondensed fluorocarbons is returned to the pipe 21 via the pipe 29 and is again subjected to the adsorption and desorption process together with the treated air.

Next, the operation of the fluorocarbon recovery device configured as described above will be explained.

First, the adsorbent stored in the first adsorption tower 1 has been regenerated and is in an active state, and the adsorbent stored in the second adsorption tower 2 has been adsorbed and has sufficiently adsorbed fluorocarbons. Suppose we are in a state where Therefore, the first adsorption tower 1 carries out the adsorption process, and the second adsorption tower 2 carries out the desorption process.

In this case, the on-off valves Vl and V2 are opened, and the on-off valves V5,
Leave Vo and V9 quiet. Flow rate adjustment valve V IO+ V
1° is set so that a predetermined amount of regeneration gas flows through when the pressure inside the adsorption tower is reduced. Also, on-off valve V3+V4+V7+
V8 is closed, on-off valve Vll is opened, and flow rate adjustment valve V1° is set to a predetermined opening degree to allow a predetermined flow rate of regeneration gas to flow through this flow rate adjustment valve V1°. In addition, processing blower 3
is always driven, and the vacuum pump 6 and cooling cleaning blower 5 are selectively driven.

Note that at the beginning of this process, the vacuum pump 6 is in an operating state, and the cooling cleaning blower 5 is in an inoperative state.

Then, the air containing fluorocarbons is sucked by the blower 3 through the piping 21, and is supplied to the cooler 4 through the piping 22 to be cooled. As a result, the fluorocarbon-containing air is cooled to a low temperature at which the adsorption efficiency of the adsorbent is high, and then sent into the first adsorption tower 1 by the blower 3 via the pipes 23 and 23a. An adsorbent 40 is housed in the adsorption tower 1,
The air containing fluorocarbons passes through the adsorbent 41 of the adsorbent 40, and the fluorocarbons contained therein are adsorbed by the adsorbent 41. The clean air from which Freon has been removed is supplied to the pipe 24a.

24 to the atmosphere.

On the other hand, in the second adsorption tower 2, the inside of the adsorption tower 2 is sucked by the vacuum pump 6 through the piping 28, 28b, and the purified air flowing through the piping 24 is supplied to a predetermined level through the flow rate adjustment valve ■1°. is introduced at a flow rate of

In the adsorbent 40 in the adsorption tower 2, electricity is supplied to the sheet heater 42 to cause the sheet heater 42 to generate resistance heat, and the adsorbent 40 in contact with the sheet heater 42
Heat 1. As a result, the fluorocarbons adsorbed on this adsorbent 41 are desorbed, and the fluorocarbons desorbed from the adsorbent 41 are removed using the purified air introduced into the adsorption tower 2 through the flow rate regulating valve v1 as a carrier gas. is sucked by the vacuum pump 6 and supplied to the cooler 7. The air discharged from the adsorption tower 2 in which the fluorocarbons are concentrated is cooled by chilled water in the cooler 7, and the fluorocarbons and water in the discharged air are condensed to form a fluorocarbon liquid and water, which are then supplied to the separator 8. The air containing uncondensed fluorocarbons is returned from the separator 8 to the piping 21 via the piping 29, and together with the fluorocarbon-containing air sent through the piping 21, it is sent to the processing blower 3.
is introduced into the first adsorption tower 1 where an adsorption process is being carried out. Therefore, the air containing uncondensed fluorocarbons after condensing fluorocarbons and moisture from the fluorocarbon-concentrated air in the cooler 8 is supplied to the first adsorption tower 1, where the uncondensed fluorocarbons are adsorbed and removed.

In the separator 8, the Freon liquid and water are separated by specific gravity,
The water is discharged and the fluorocarbon liquid is collected in the tank 9.

Next, after sufficiently desorbing Freon 10- from the adsorbent in the second adsorption tower 2, the first adsorption tower engineer removes the second adsorption tower 2 from the desorption process while the adsorption process is still being performed. Move to cooling process. That is, valve Vl+V2. ■5. v6.
v8 and valve V3. Leave v4 as is, open on-off valve v8,
Close the on-off valve V11.

By doing this, air is supplied through the pipe 26b into the adsorption tower 2, which had been under reduced pressure until then, and the pressure becomes normal. Next, on-off valve V8 is opened, leaving the other on-off valves as they are, and on-off valve V4. V7 is closed.

Further, the vacuum pump 6 stops its operation, and the cooling cleaning blower 5 starts its operation. Then, the purified air flowing through the pipe 24 is sucked by the cooling cleaning blower 5 and introduced into the second adsorption tower 2 via the pipe 24b. After this purified air cools the adsorbent in the second adsorption tower 2 as a cooling gas, it is returned to the pipe 22 via the pipes 25b and 25, and is supplied to the first adsorption tower 1 together with the fluorocarbon-containing air. As a result, the fluorocarbons mixed into the cooling gas when flowing through the second adsorption tower 2 are adsorbed by the adsorbent in the first adsorption tower 1 and removed.

Thereafter, the first adsorption tower 1 is switched to the desorption process, and the second adsorption tower 2 is switched to the adsorption process, and thereafter, such operations are alternately repeated to recover fluorocarbons from the fluorocarbon-containing air.

In this way, the adsorbent can be regenerated without the use of water vapor, which may generate acids.

[Problems to be Solved by the Invention] However, the dual fluorocarbon recovery device has the following drawbacks.

When the fluorocarbon concentration in the fluorocarbon-containing air to be treated is low, the fluorocarbon concentration in the fluorocarbon concentrated gas sucked by the vacuum pump 6 and sent to the cooler 7 is also low.As a result, the cooling condensation in the cooler 7 Efficiency is low and separator 8
A large amount of uncondensed fluorocarbon is contained in the air returned to the piping 21 from the air. Therefore, in the adsorption towers 1 and 2, in addition to the fluorocarbons in the fluorocarbon-containing air that is sent into the device via the two pipes, it is also necessary to adsorb and process the fluorocarbons in the return air that is circulated within the device. Moreover, since the amount of fluorocarbon in this return air is relatively large, the required amount of adsorbent to be stored in the adsorption tower increases. For this reason,
The disadvantage is that the equipment cost is high.

In addition, since the amount of return air returned from the separator 8 to the adsorption towers 1 and 2 increases, in the adsorption towers 1 and 2, -
The ratio of highly concentrated air being reconcentrated as return air increases, resulting in a wasteful concentration (adsorption and desorption) process.

Then, the adsorbent is used to adsorb and recover the fluorocarbons in this return air, and the proportion of the adsorbent that should be used to treat the fluorocarbon-containing air that should originally be adsorbed and recovered, that is, the fluorocarbon-containing air supplied from the outside system, is reduced. This is extremely inefficient. For example, in Freon 113, the cooler 7 has a temperature of 5°C.
Even if the carrier gas is cooled and condensed and separated, the carrier gas contains a high concentration of uncondensed fluorocarbons, which is theoretically 18%, but actually exceeds 20%, and is returned to the inlet of the adsorption towers 1 and 2. Become. The Freon 11 contains an even higher concentration of uncondensed Freon, about 53%, and is returned to the inlets of the adsorption towers 1 and 2. Because of the large amount of uncondensed fluorocarbons in the return air, there is a drawback that the concentration process using the adsorption tower 1.2 is not effectively used to condense the fluorocarbon-containing air introduced from the outside system. .

Furthermore, fluorocarbons are sometimes used as a mixture of fluorocarbon 113 and ethanol, but in this case, ethanol is dissolved in the water that is condensed in the condenser cooler 7 and collected together with the fluorocarbon liquid in the separator 8. Because of this,
The composition of the recovered fluorocarbon solution (mixing ratio of fluorocarbon solution and ethanol) is significantly different from that of the unused (undiluted) solution.

For this reason, it cannot be reused as it is, and for reuse it must be prepared again, which has the drawback of requiring double effort.

The present invention has been made in view of such problems, and includes:
The purpose of the present invention is to provide a solvent recovery device that can improve the condensation efficiency of the solvent, make the concentration process using an adsorption tower highly efficient, and reduce the amount of adsorbent required and the cost of the device. do.

[Means for Solving the Problems] 14- The solvent recovery device according to the present invention comprises a plurality of solvent adsorbents each containing a monolithic adsorbent whose main component is activated carbon and a heat supply member in contact with the adsorbent. an adsorption tower; a solvent-containing gas flow means for selectively passing a solvent-containing process gas through the plurality of adsorption towers to obtain clean gas; and a dehumidification means for dehumidifying the exhaust gas from the adsorption tower. and a condensing cooler that introduces and cools the exhaust gas dehumidified by the dehumidifying means and condenses the solvent in the exhaust gas.

[Operation] In the present invention, among the plurality of adsorption towers, in the adsorption tower performing the solvent desorption process, the monolithic adsorbent is heated by its heat supply member, and the solvent that has been adsorbed up to that point is heated. Attach and detach.

The solvent-concentrated gas containing the solvent desorbed from the adsorbent is dehumidified by a dehumidifying means and then cooled by a condensing cooler to condense the solvent and separate it from the gas. In this case, since the solvent concentrated gas is dehumidified in advance before being condensed by the condensing cooler, the water will freeze in the condensing cooler even if it is cooled to an extremely low temperature. Never. For this reason, while conventional recovery equipment could only cool down to 5°C using a condensing cooler,
In the present invention, it is possible to cool down to several tens of degrees Celsius below zero, for example. As a result, the concentration of uncondensed solvent that is not condensed in the condensing cooler can be extremely reduced, so that the solvent can be recovered with high efficiency. Therefore, even if the solvent-containing gas supplied to the adsorption tower from the outside has a relatively low concentration, and therefore the concentration of the solvent desorbed from the adsorption tower is low, the solvent introduced into the condensing cooler Since the condensed gas is a dry gas with a dew point of, for example, −60° C., its cooling temperature can be made extremely low, and extremely high condensation efficiency can be obtained in the condensing cooler.

In addition, when a gas containing uncondensed solvent is reintroduced into the adsorption tower and the uncondensed solvent is adsorbed by the adsorption tower, the concentration of solvent in this return gas becomes extremely low, so it is necessary to reconcentrate it using the adsorption tower. The amount of uncondensed solvent in the return gas can be significantly reduced. Therefore, since the adsorption tower is effectively used for concentrating the solvent-containing gas introduced from the outside system, the required amount of adsorbent in the adsorption tower is reduced, and the equipment cost is low.

Furthermore, since the amount of water in the condensed liquid is significantly reduced, a separator for separating the condensed fluorocarbon liquid and water by specific gravity becomes unnecessary. For example, when recovering ethanol-containing fluorocarbons, since there is no water in the recovered liquid, the ethanol does not dissolve in water and disappear, and the component ratio is almost the same as that of unused ethanol-containing fluorocarbon liquids. The ethanol is mixed into the fluorocarbon solution and recovered. Therefore, this recovered ethanol-containing fluorocarbon solution does not have to be re-formulated.
It can be reused as is.

[Example code] Examples of the present invention will be specifically described below.

FIG. 1 is a block diagram showing a solvent recovery device according to an embodiment of the present invention. In FIG. 1, the same parts as in FIG. 17-2 are given the same reference numerals, and detailed explanation thereof will be omitted.

In this embodiment, a dehumidifying adsorption tower 10.11 as a dehumidifying means is interposed in a pipe 28 that leads the exhaust gas from the adsorption towers 1 and 2 to the condensing cooler 7. The outlet of the vacuum pump 6 is
The dehumidification adsorption tower 10.
The dehumidification adsorption tower i
Concentrated gas discharge ports o and ti are connected to the condensing cooler 7 via pipes 31a and 31b, respectively. Each pipe 30a.

Opening/closing valves v21°v2°+Veal V24 are interposed in 30b, 31a, and 31b, respectively. Further, a pipe 32 communicating with the atmosphere is connected to the regenerated air inlet of the dehumidification adsorption tower 10.11 via branch pipes 32a and 32b branching from the pipe 32, respectively.

A blower 13 is installed in the pipe 32, and the blower 13 allows atmospheric air to be introduced into the dehumidification adsorption tower 10.11 via the pipes 32.32a and 32b. Each pipe 32a, 32b has an on-off valve V2B1.
V28 is installed. Furthermore, pipes 33a and 33b are connected to the regenerated air outlet of the dehumidification adsorption tower 10.11, respectively.
33b joins the pipe 33, and the dehumidification adsorption tower 10.1
The regenerated air of No. 1 is discharged into the atmosphere from a pipe 33. Pipes 33a and 33b each have an on-off valve V.
251 V27 is installed.

The dehumidifying adsorption tower 1.0.11 contains an adsorbent that adsorbs water but does not adsorb solvents such as fluorocarbons. Zeolite 3A is an example of such an adsorbent. This zeolite 3A has an adsorption pore size of 3.0 mm and adsorbs water molecules with a molecular size of 2.8 mm, but does not adsorb fluorocarbon 113 with a molecular size of 2.8 mm. Also, in the recovery of Freon 113 mixed with alcohol such as ethanol, if the zeolite 3A is used, only water molecules will be adsorbed and removed.

In addition, a heater (not shown) that generates resistance heat when energized is installed in each dehumidifying adsorption tower 10.11, and by energizing this heater, the adsorbent in the dehumidifying adsorption tower 10.11 is It is heated to approximately 200°C, thereby desorbing the moisture adsorbed by this adsorbent.

In this embodiment, the condensing cooler 7 is directly connected to the solvent tank 9, and a separator 8 (see FIG. 2) for separating water and fluorocarbon liquid by specific gravity is not installed. Therefore, the air containing uncondensed chlorofluorocarbons is returned from the solvent tank 9 to the piping 21 via the piping 29 together with the evaporated fluorocarbons in the solvent tank 9.

Next, the operation of the solvent recovery device configured as described above will be explained.

First, it is assumed that the first adsorption tower 1 carries out a fluorocarbon adsorption process, and the second adsorption tower 2 carries out a fluorocarbon desorption process. Therefore, the adsorbent in the first adsorption tower 1 is in an active state, and the adsorbent in the second adsorption tower 2 is adsorbing fluorocarbons in a saturated state or a state close to it. Further, it is assumed that the dehumidification adsorption tower 10 carries out the water adsorption process, and the dehumidification adsorption tower 11 carries out the water desorption process. Therefore, the adsorbent in the dehumidifying adsorption tower 10 is in an active state, and the adsorbent in the adsorption tower 11 is adsorbing water at or near saturation. In this case, first open the on-off valves VI and v2, then open the on-off valves V, , V6 and v9.
close. Also, on-off valve V3. v4. V7. Leap v8, open the on-off valve V I l and t7r. On the other hand, the on-off valve V2
1 + V 22 + V 27 + V 28 is open, on-off valve V 231 V 241 V 2ffiI V 2B
is closed. Then, the vacuum pump 6 is driven, and the blower 3 for blowing fluorocarbon-containing air and the blower 13 for blowing regenerated air are always driven.

Then, the fluorocarbon-containing air is supplied to the cooler 4 by the processing blower 3 and cooled, becoming low-temperature air with high adsorption efficiency, and then sent into the first adsorption tower 1. This fluorocarbon-containing air is passed through the adsorbent of the adsorbent housed in the first adsorption tower 1, and after the fluorocarbons are adsorbed and removed, it is discharged into the atmosphere as clean air.

On the other hand, in the second adsorption tower 2, the adsorbent 41 is heated by energizing the sheet heater 42 of the adsorbent 40, and the adsorbent 41 desorbs the fluorocarbons adsorbed in the previous adsorption step. The second suction 21-adsorption tower 2 is suctioned by the vacuum pump 6 and placed under negative pressure, so a small amount of purified air is introduced into the second adsorption tower 2 through the flow rate regulating valve V1°. has been done. The fluorocarbons desorbed from the adsorbent in the second adsorption tower 2 are sucked by the vacuum pump 6 using the purified air as carrier air and supplied to the dehumidification adsorption tower 10. The fluorocarbon-enriched air containing the desorbed fluorocarbons is passed through a moisture adsorbent in the dehumidification adsorption tower 10 to remove its moisture.

Next, it is dehumidified by this dehumidification adsorption tower 10 to a low dew point (
For example, the dried fluorocarbon condensed air at -60°C is supplied to the condensing cooler 7. The fluorocarbons contained in this fluorocarbon-concentrated air are cooled and condensed by the condensing cooler 7 to become a fluorocarbon liquid, which is collected and stored in the solvent tank 9. Air containing uncondensed fluorocarbons discharged from the cooler 7 is supplied from the solvent tank 9 to the pipe 21 via the pipe 29.

This uncondensed CFC-containing air flows through the first adsorption tower 1 (22-) together with the treated air (CFC-containing air) introduced via the pipe 21, and the remaining CFCs are removed from the first adsorption tower 1. It is adsorbed by an adsorbent and is discharged into the atmosphere as clean air.

In addition, in the dehumidification and adsorption tower 11, the adsorbent in the dehumidification and adsorption tower 11 is heated by energizing the heater, and as a result, this adsorption material absorbs the water that was adsorbed in the previous moisture adsorption process. Attach and detach.

The blower 13 is connected to the piping 32. Since air is passed through the dehumidification and adsorption tower 11 through the dehumidification and adsorption tower 11 through the dehumidification and adsorption tower 11, the water desorbed from the adsorbent in the dehumidification and adsorption tower 11 is discharged from the dehumidification and adsorption tower 11 using this air as a carrier gas. It will be done. In this manner, while the dehumidification and adsorption tower 10 is performing the dehumidification process of the concentrated fluorocarbon gas, the dehumidification and adsorption tower 11 is performing the regeneration process of the adsorbent.

Next, after the adsorbent in the dehumidification and adsorption tower 11 is sufficiently regenerated, the power supply to the heater in the dehumidification and adsorption tower 11 is stopped. Then, the adsorbent in the dehumidification adsorption tower 11 is absorbed by the blower 13.
It is cooled by the flow of air sent in by. This increases the adsorption efficiency in the next adsorption step.

Next, after the adsorbent in the second adsorption tower 2 has been sufficiently desorbed, the second adsorption tower 2 moves to a step of cooling the adsorbent. That is, after closing the on-off valve V++ and opening the on-off valve V8 to bring the inside of the adsorption tower 2 to normal pressure, the on-off valve V8 is closed again. and,
The vacuum pump 6 is stopped, and then the on-off valve V4. Open V7 and start driving the cooling blower 5. Further, the power supply to the seat heater 42 of the adsorbent 40 housed in the second adsorption tower 2 is stopped.

As a result, inside the second adsorption tower 2, the pipes 24b, 25
The purified air sucked into the cooling blower 5 through the cooling blower 5 through the cooling blower 5 flows as cooling air, and the adsorbent in the second adsorption tower 2, which has been heated in the previous desorption step, is cooled. While this cooling air flows through the second adsorption tower 2, fluorocarbons in the second adsorption tower 2 are mixed into the cooling air, so the cooling air discharged from the second adsorption tower 2 is passed through the cooler. After being returned to the upstream side of 4, it is supplied to the first adsorption tower 1 which is performing an adsorption step, and the mixed fluorocarbons are adsorbed and removed.

Next, after the adsorbent in the first adsorption tower 1 is saturated or has reached a state close to it, the first adsorption tower 1 undergoes a desorption process and a second adsorption process.
The adsorption tower 2 moves to the adsorption step.

That is, the on-off valve vl, ■2. V6. Close vo, open/close valve V8
Set to open. Also, open the on-off valves V a and V 4,
Close the on-off valve V71V11. And vacuum pump 6
is driven, and the cooling blower 5 is stopped. Further, the sheet heater 42 of the adsorbent 40 housed in the first adsorption tower 1 is energized to heat the adsorbent 41, thereby desorbing fluorocarbons from the adsorbent 41 in the first adsorption tower 1.

As a result, the first adsorption tower 1 performs the desorption process, and the second adsorption tower 2 performs the adsorption process. After the adsorbent in the first adsorption tower 1 has sufficiently desorbed fluorocarbons, the first adsorption tower 1 moves to a cooling process. That is, the power supply to the seat heater 42 is stopped, the on-off valve v9 is closed, and the on-off valve V is closed. After opening the adsorption tower 1 to normal pressure, the on-off valve v6 is closed again.

Also, the vacuum pump 6 is stopped, and then the on-off valve v2. ■
5 is opened, and the processing blower 5 is started to be driven (25-). As a result, the purified air in the pipe 24 is introduced into the first adsorption tower 1, and the adsorbent in the first adsorption tower 1, which had been heated in the previous desorption process, is cooled by the flow of purified air. be done.

Thereafter, the first adsorption tower 1 and the second adsorption tower 2 alternately repeat the adsorption process and the desorption and cooling process. As a result, the fluorocarbon-containing air is continuously adsorbed and clean air is obtained, and the condensed and separated fluorocarbon liquid is collected into the solvent tank 9.

On the other hand, in the dehumidification adsorption tower 10, when the built-in adsorbent is saturated or in a state close to it, the on-off valve V21
1 V221 V271 V2g open/close valve V 25
゜V 281 V 2] Open I V 24. Further, the heater in the dehumidifying adsorption tower 10 is energized to heat the adsorbent.

As a result, the freon-enriched air discharged from the first adsorption tower 1 or the second adsorption tower 2 is introduced into the dehumidification and adsorption tower 11, and is dehumidified by flowing through the adsorbent in the dehumidification and adsorption tower 11. On the other hand, in the dehumidification adsorption tower 10, the adsorbent is heated by the resistance heat generated by the heater, and as a result, the moisture adsorbed in the previous adsorption step is desorbed. This desorbed water is transferred to the blower 1.
3 is discharged from the dehumidification adsorption tower 10. After the regeneration process in the dehumidification/adsorption tower 10 is completed, the dehumidification/adsorption tower 10 stops energizing the heater and moves to a cooling process.

In this manner, the dehumidification adsorption tower 10.11 also continuously dehumidifies the freon-concentrated air supplied by the vacuum pump 6 by alternately repeating the adsorption process and the regeneration (desorption) and cooling process.

In this case, the switching timing between the adsorption process in the dehumidification adsorption tower 10.11 and the regeneration and cooling process is the same as the adsorption process in the first and second adsorption towers 1 and 2 concentrating the fluorocarbon-containing air and the desorption The timing may be the same as the timing at which the cooling process and the cooling process are switched, or the timing may be different.

In this embodiment, air containing fluorocarbons introduced into the apparatus from an external system passes through adsorption towers 1 and 2, and the fluorocarbons contained therein are adsorbed and removed by adsorbents in the adsorption towers 1 and 2. Then, by applying electricity to the seat heater and heating the adsorbent, the fluorocarbons adsorbed by the adsorbent are desorbed. In this case, when the fluorocarbon concentration in the fluorocarbon-containing air introduced into the apparatus is low, the fluorocarbon concentration in the fluorocarbon-enriched air desorbed from the adsorption tower 1.2 is also low. but,
This medium-concentration freon-enriched air is dehumidified by adsorption towers 10 and 11, and then supplied to the condensing cooler 7. In this way, Freon-enriched air is dehumidified to a low dew point (e.g. -60
℃) is supplied to the condensing cooler 7 as dry air.
In the condensing cooler 7, the freon-concentrated air can be cooled to an extremely low temperature of, for example, -30°C.

Therefore, this fluorocarbon-concentrated air can be condensed with extremely high efficiency, and the fluorocarbon liquid can be recovered with high efficiency. In addition, when fluorocarbons are not used alone but in a mixture with other solvents such as ethanol,
Before these solvents condense, water is removed from the condensed air, so there is substantially no water in the condensate. Therefore, even if a water-soluble solvent such as ethanol is mixed, a chlorofluorocarbon/ethanol mixture having substantially the same composition as the initial composition is recovered in the solvent tank 9.

In addition, since the condensation efficiency in the condensing cooler 7 is high, the solvent is returned to the piping 21 from the condensing cooler 7 via the solvent tank 9.
Furthermore, the amount of uncondensed fluorocarbon in the return air that is reintroduced to the adsorption towers 1 and 2 via the processing blower 3 and cooler 4 is small. For example, if the fluorocarbon-enriched air introduced into the condensing cooler 7 as in the past contains moisture that is unavoidably mixed in the fluorocarbon-containing air introduced from outside the system, as described above, In the condensing cooler 7, cooling is limited to 5°C to prevent freezing, and theoretically more than 18%, in practice, more than 20% of uncondensed fluorocarbons remain. When concentrated air is dehumidified in advance and then condensed, the remaining uncondensed CFC is actually 3%.
decreases to Therefore, very little of the fluorocarbons adsorbed and removed by the adsorption towers 1 and 2 are circulated within the system, and are exclusively introduced into the apparatus from outside the system. For this reason,
Adsorption towers 1 and 2 are used exclusively for adsorption treatment of fluorocarbon-containing air that should originally be adsorbed and removed.Since they can adsorb fluorocarbons extremely efficiently, the required amount of adsorbent in adsorption towers 1 and 2 is It is sufficient to have a small amount, and the cost of the device can be reduced.

Also, if the inlet concentration is as low as 200 ppm, the second
In the conventional solvent recovery device shown in the figure, even if the fluorocarbons only circulate inside the device and do not condense, in this example device, the fluorocarbon-concentrated air discharged from the adsorption tower 1.2 After being dehumidified, it is supplied to the condensing cooler 7, so that the condensing cooler 7 can sufficiently condense the fluorocarbons by strong cooling. Therefore, in the apparatus of this embodiment, fluorocarbons can be recovered with high efficiency from air containing low concentrations of fluorocarbons.

Note that the present invention is of course applicable not only to the recovery of fluorocarbons but also to the recovery of various other solvents.

[Effects of the Invention] According to the present invention, the solvent-containing gas is concentrated by the adsorption tower and then dehumidified by the dehumidifying means and cooled and condensed in a dry state, so that it is not allowed to enter the apparatus from the outside system. Even when the concentration of the solvent in the solvent-containing gas that is introduced as the gas to be treated is extremely low, the condensation efficiency in the condensing cooler is high, and the solvent is recovered with extremely high efficiency. In addition, because the condensation cooler has a high condensation efficiency, the amount of uncondensed solvent (solvent circulated within the device) is extremely small, and when this is returned to the adsorption tower and subjected to concentration again, the amount of adsorbent required in the adsorption tower is small. That's enough,
Equipment costs can be reduced. Furthermore, since the condensate does not contain water, even if a solvent that is easily soluble in water such as ethanol is mixed with the main solvent such as Freon, the solvent can be recovered with almost the same composition as before use. be able to. Therefore, the recovered solvent can be reused without being re-blended, the gas containing the solvent can be recovered without being released outside the system, and the recovered solvent can also be reused as is, resulting in environmental and industrial benefits. It can be put to good use.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a solvent recovery device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional solvent recovery device, and FIG. 3 is a schematic perspective view showing an adsorbent that does not use steam. be. 1.2; Adsorption tower, 3; Processing blower, 4; Cooler, 5; Cooling blower, 6; Vacuum pump, 7; Condensation cooler, 8; Separator, 9; Solvent tank, 10.11. ;Dehumidification adsorption tower

Claims (4)

[Claims] (1) A plurality of adsorption towers housing a solvent adsorbent consisting of a monolithic adsorbent whose main component is activated carbon and a heat supply member in contact with the adsorbent, and a treated gas containing a solvent in the plurality of adsorption towers. a solvent-containing gas flow means for selectively passing through the gas to obtain clean gas; a dehumidification means for dehumidifying the exhaust gas from the adsorption tower; and a dehumidification means for introducing and cooling the exhaust gas dehumidified by the dehumidification means. A solvent recovery device comprising: a condensing cooler that condenses the solvent in the exhaust gas. (2) The solvent according to claim 1, further comprising cooling gas flow means for cooling the adsorbent in the adsorption tower by flowing cooling gas and then returning the exhaust gas to the treated gas. Collection device. (3) The dehumidifying means includes a dehumidifying adsorption tower containing a moisture adsorbent, and a gas flow means for selectively passing the exhaust gas and high-temperature regeneration gas through the dehumidifying adsorption tower. The solvent recovery device according to claim 1 or 2. (4) A plurality of the dehumidification and adsorption towers are installed, and the exhaust gas and the regeneration gas are alternately passed through one group of dehumidification and adsorption towers and the other group of dehumidification and adsorption towers, so that the exhaust gas is continuously 4. The solvent recovery device according to claim 3, wherein the solvent recovery device performs dehumidification treatment.