JPH02307527A - Solvent adsorbing material and solvent recovery apparatus - Google Patents

Abstract

PURPOSE:To enhance adsorbing capacity by compounding a non-conductive substance with activated carbon being a main component and setting said activated carbon to specific resistivity. CONSTITUTION:Opening and closing valves 10, 12 are opened and an opening and closing valve 14 is closed to supply fluorocarbon-containing air to an adsorbing tower 1 by a blower 5. Fluorocarbon in fluorocarbon-containing air is adsorbed by an adsorbing material at room temp. and purified gas from which fluorocarbon is removed is discharged from the adsorbing tower L. After the adsorbing capacity of the adsorbing material 2 of a honeycomb molded body is saturated, the supply of fluorocarbon-containing air is stopped and, when a switch 4 is turned ON, the adsorbing material 2 receives the supply of current from a power supply 33 to be subjected to resistance heating. Therefore, the adsorbed fluorocarbon is desorbed to be sucked by a pump 6 and supplied to a condenser 7 to be condensed while the condensate is separated into water and a fluorocarbon liquid by a separator 8. As the adsorbing material, a molded body prepared by molding a compound of a non-conductive substance with activated carbon is used. By this method, energy can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solvent adsorbent that adsorbs a solvent and a batch-type solvent recovery device that uses this solvent adsorbent to recover the solvent from a solvent-containing gas. In particular, we propose a solvent recovery technique in which the solvent adsorbent is heated with electricity during regeneration.

[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. Among them, air pollution caused by fluorocarbon gases containing fluoride is attracting attention as a serious problem on a global scale, and for this reason, fluorocarbon gas emissions are being regulated.

The use of these fluorocarbon gas emission regulations has been advocated to be discontinued in the future, but until a replacement product is developed, the current state of the art is to prevent the fluorocarbon gas that was previously released into the atmosphere from being emitted outside the system. The next best option is to collect and reuse it. For this reason, various fluorocarbon gas recovery devices are used.

FIG. 5 is a block diagram showing a conventional patch type fluorocarbon gas recovery device.

The fluorocarbon gas recovery equipment can be used for various industrial solvents other than fluorocarbons, just by changing the conditions, but here, the fluorocarbon gas recovery equipment will be described for a typical fluorocarbon gas among various fluorinated hydrocarbon gases. do. That is, this fluorocarbon gas recovery device has two adsorption towers, a first adsorption tower 21 and a second adsorption tower 22, and by alternately repeating a batch-type adsorption process and a desorption process (release of gas from an adsorbent). , both adsorption towers 21 and 22 enable continuous fluorocarbon gas recovery processing. Each of the adsorption towers 21 and 22 is filled with a fluorocarbon adsorbent such as activated carbon.

The fluorocarbon-containing air 23 is passed through the pipe 41 (
41a, 41b) to be branched and supplied to the adsorption tower 21.22. On-off valves 28 and 29 are installed in each of the pipes 41 at 4 l b, and these on-off valves 28 and 29 are used to control the fluorocarbon-containing air 2 to each adsorption tower 21 and 22.
Control the supply of 3.

The cooling air 24 is supplied to the piping 42 (42a, 42a,
42 b) to the adsorption column 21.22. And, on-off valves 30 are provided in the pipes 42a and 42b, respectively.
．． 31 is interposed, and this on-off valve 30.31 controls the supply of cooling air to each adsorption tower 21.22.

Further, the steam 25 is branched and supplied to the adsorption towers 21.22 via piping 43 (43a, 43b), and on-off valves 34.35 are interposed in the piping 43a, 43b, respectively. These on-off valves 34 and 36 are connected to adsorption towers 41 and 41, respectively.
The supply of steam for regenerating the adsorbent to 42 is controlled.

On the other hand, pipes 44 are provided at the gas discharge ports of the adsorption towers 21 and 22, respectively.
a, 44b are connected, and these pipes 44a, 44b
are collectively connected to a pipe 44. Each pipe 44a
, 44 b is equipped with on-off valves 32 and 33,
The discharge of purified air 26 from the adsorption towers 21,22 is controlled.

Purified air 26 is released from the pipe 44 into the atmosphere.

Further, pipes 46a and 45b are connected to other gas discharge ports of the adsorption towers 41 and 42, respectively.
5b are arranged to gather at the pipe 45. and,
Each pipe 45a, 45b is provided with an on-off valve 38, 37, respectively, to control the discharge of the regenerated gas from each adsorption tower 21, 22. A condenser 38 is connected to the pipe 45, and the gas after regeneration is sent to the condenser 38.
It is cooled by cooling water and liquefied. This liquid is sent to the water separator 39 via piping 46, and the water in the liquid and the fluorocarbon liquid are separated by the water separator 39. This fluorocarbon liquid is sent to the storage tank 40 via piping 47 and stored therein.

Next, the operation of the batch type fluorocarbon gas recovery apparatus configured as described above will be explained.

First, the adsorbent stored in the first adsorption tower 21 has been regenerated and is in an active state, and the adsorbent stored in the second adsorption tower 22 has been adsorbed and has sufficiently absorbed CFCs. Suppose that it is in a state of adsorption.

In this case, open the on-off valves 28 and 32, and open the on-off valves 29 and 33.
Close the on-off valve 30.31, close the on-off valve 34°3θ,
Open the on-off valves 35 and 37. Then, the fluorocarbon-containing air 23 is sent into the adsorption tower 21 via the pipe 41a by the blower 27a.

This fluorocarbon-containing air 23 passes through an adsorbent in the adsorption tower 21, and after the fluorocarbons are adsorbed and removed, it is discharged from the adsorption tower 21 as purified air 26 via a pipe 44a.

On the other hand, water vapor (hereinafter simply referred to as steam) 25 is supplied to the adsorption tower 22 through a pipe 43b, and this vapor passes through an adsorbent in the adsorption tower 22 and is adsorbed by this adsorption material in the previous adsorption step. The energy of the steam heats and desorbs the fluorocarbons and moisture. This fluorocarbon and moisture are sent to the condenser 38 through the pipe 45 together with the exhaust steam, and are cooled in the condenser 38. As a result, the fluorocarbon gas and water are liquefied and become a mixed liquid of fluorocarbon liquid and water, and this mixed liquid is sent to the water separator 39.
Separated into water and Freon liquid. The fluorocarbon liquid is collected in the storage tank 40.

Next, after a certain period of time has elapsed, the on-off valves 28 and 32 remain open and the adsorption process in the first adsorption tower 21 is continued, while the on-off valves 3 and 32 remain open.
5.37 is closed to stop the desorption process of the second adsorption tower 22. Then, the on-off valves 31 and 33 are opened to supply the cooling air 24 containing little or no CFCs to the adsorption tower 22, and this cooling air is passed through the adsorbent in the adsorption tower 22, allowing the desorption by steam to be carried out as before. The adsorbent such as activated carbon that has absorbed moisture during the process is dried and cooled. The cooled gas discharged from the adsorption tower 22 is discharged to the atmosphere together with purified air via pipes 44b and 44.

Next, after a certain period of time has passed, the on-off valve 29 is opened, and the on-off valve 34 is opened.
．． 38 is opened, the on-off valve 28.32 is closed, and the on-off valve 31' is closed.The on-off valve 33 remains open, and the on-off valve 30.3 is closed.
5.37 remains closed.

As a result, the fluorocarbon-containing air 23 passes through the adsorbent of the second adsorption tower 22, and the fluorocarbons are adsorbed.

Further, the steam 25 passes through the adsorbent of the first adsorption tower to desorb fluorocarbons. The gas containing fluorocarbons and moisture is sent to the condenser 38 and the moisture mWA 39, and the fluorocarbon liquid is recovered.

Then, after a certain period of time has passed, the on-off valves 34 and 38 are closed,
The on-off valves 30 and 32 are opened to supply cooling air 24 to the first adsorption tower. Thereby, the first adsorption tower moves from the desorption process to the cooling (drying) process.

In this way, the adsorption process, desorption process and cooling process are carried out in one step.
Each on-off valve switches as a cycle, and the fluorocarbon-containing air 2
Collect the Freon liquid from 3. When the first adsorption tower 21 is in the adsorption process, the second adsorption tower 22 is in the desorption process and the cooling process, and when the second adsorption tower 22 is in the adsorption process, the first adsorption tower is in the adsorption process. 21 is carrying out the desorption process and the cooling process. As a result, fluorocarbon gas can be continuously recovered from the exhaust air. In addition, when the recovery of fluorocarbon gas does not need to be continuous, the adsorption, desorption, and cooling steps may be performed at fixed time intervals using only one adsorption tower. Furthermore, if the time for the adsorption step and the total time for the desorption and cooling steps do not match, three or more adsorption towers may be used.

Incidentally, the above-mentioned batch-type fluorocarbon gas recovery apparatus has conventionally used activated carbon in the form of pellets, granules, or fibers (Japanese Patent Application Laid-Open No. 174923/1983).

These are made by arranging a large number of granules with a particle size of about 0.5 to 1 wm and allowing the fluorocarbon-containing gas to pass between the particles, or by making it into a felt shape with thin fibers and passing the fluorocarbon-containing gas through the felt. The Freon is removed by passing it through.

Such an adsorbent is not defined as a molded body here.

[Problems to be Solved by the Invention] However, in the vapor desorption method in which organic solvents such as fluorocarbons adsorbed on adsorbents are desorbed by steam, there is a problem that generation of acids cannot be avoided. be. In other words, fluorocarbons themselves are mainly composed of carbon, chlorine, and fluorine, and are extremely stable substances, but if they remain adsorbed on activated carbon for a long time under conditions exposed to steam, some of the fluorocarbons will decompose. However, hydrochloric acid and hydrofluoric acid are generated. Therefore, if the recovered fluorocarbon is repeatedly collected and reused under such circumstances, the fluorocarbon purity in the recovered fluorocarbon will decrease and the acid concentration will increase, eventually making it unfit for normal use. Furthermore, the generated acid will also be mixed into the waste water and purified gas, resulting in new secondary pollution.

Furthermore, when recovering azeotropic CFCs containing alcohol, the alcohol dissolves in water and most of it is discharged with the wastewater, so BOD and CO in the wastewater are
Measures D will have to be taken.

,Furthermore, when using steam as the regeneration gas,
Since it is necessary to install new steam piping and a steam boiler, there is a drawback that equipment costs, maintenance costs, and running costs are high. Furthermore, in the vapor desorption method, since water basically remains on the surface of the adsorbent, it is necessary to provide a drying step to remove the water on the surface of the adsorbent prior to the adsorption step, but in the conventional method, Since the adsorbent cannot be sufficiently dried, it cannot fully demonstrate its inherent adsorption ability, and a large amount of adsorbent is required.

As described above, the conventional techniques that use water vapor due to its recovery principle have various drawbacks due to moisture.

The present invention has been made in view of such problems, and includes:
By regenerating the adsorbent in a dry state without using steam to regenerate the adsorbent, it simplifies wastewater treatment, prevents the generation of acids, improves the recovery efficiency of alcohol content, and improves the quality of recovered organic fluorocarbons. The purpose of the present invention is to provide a heated air regeneration type fluorocarbon recovery device that can improve the Another object of the present invention is to provide a solvent adsorbent having a molded body structure that can be used therein.

゛ [Means for Solving the Problems] The solvent adsorption i according to the present invention is a molded product whose main component is activated carbon and contains 10 to 25% by weight of a non-conductive substance, and which has a specific resistance as a molded product. value! ,0×lθ~1.2X
It is characterized by having a resistance of 10'Ω11 cm.

Further, the fluorocarbon recovery device according to the present invention includes an adsorption tower containing the solvent adsorbent, a continuous gas flow means for passing the solvent-containing gas through the adsorption tower to obtain clean gas, and an energizing heating means for heating the material by energizing it; an evacuation means for exhausting the inside of the adsorption tower; a condensing means for cooling the exhaust gas from the adsorption tower to condense the solvent; and flowing a solvent-containing gas through the adsorption tower. and selection means for selectively selecting between energization heating and exhaust.

[Function] The solvent adsorbent according to the present invention is a molded product whose main component is highly conductive activated carbon, to which is added 10 to 25% by weight of a non-conductive substance, and molded using an appropriate amount of binder. Therefore, a structure can be obtained in which a passage of an appropriate size is provided for passing the gas to be processed. And its specific resistance value is! , 0XIO~1.2X10QΩe as
becomes.

Essentially, if only activated carbon has solvent adsorption properties, it is necessary to recover the adsorbed solvent by the water vapor purge method described above, even if the molded body is formed as described above.

The adsorbent of the present invention has the features of a molded body and does not require the use of water vapor during desorption.

In the solvent adsorbent of the present invention, 10 to 25% of a non-conductive substance is added to activated carbon.

A non-conductive substance generally refers to an insulator, and the so-called apparent resistance of the substance should be about 10'Ω・C■ or more, and ordinary ceramic materials and non-conductive organic agents are used. be able to.

In addition, in this specification, “specific resistance value as a molded body”
(or 'molded object specific resistance value') is not the specific resistance value of a substance (raw material), but rather the specific resistance value of a material (raw material) that has been processed and has become a molded object as described above, when energized. The value measured by

When the blending ratio of the non-electroelectric substance in the adsorbent of the present invention is small, the specific resistance of the molded body becomes small, and when the blending ratio increases, the specific resistance value of the molded body becomes large. Under these trends, the performance as an adsorbent is better as the blending ratio of the non-conductive substance is lower, but in this case, the specific resistance of the molded body is small LS, so in order to conduct electricity to the molded body, it is better to There is a need for a means to minimize the resistance heat generation at the junctions, and temperature control at low voltage and large current is also required.

On the other hand, the higher the blending ratio of the non-conductive substance and the higher the specific resistance of the molded body, the easier it is to achieve the above-mentioned problems, but rapid heating requires high voltage application and absorption. There is a problem in that the adsorption properties of the material itself are impaired. As a result of various studies to solve this problem, the inventor of the present application has shown in Figure 1 the relationship between the two, with the horizontal axis representing the content of the non-conductive substance and the vertical axis representing the specific resistance value of the compact. As such, by understanding the relationship between the content of the non-conductive substance and the specific resistance value of the molded article, the range in which the present invention can be well implemented in practice is the addition of 10 to 25% of the non-conductive substance. The specific resistance value of the obtained molded product is 1.0XlO
It was found that it was in the range of ~1.2XI02 Ω·cm.

The adsorbent used in the present invention needs to be a molded body having a large number of communicating holes, and is preferably a molded body having a shape that has a large number of through holes in the air flow direction.

Furthermore, although the main component of the adsorbent is activated carbon, the specific resistance value of a honeycomb molded body containing almost no non-conductive material is 0.70Φc1, and as mentioned above, temperature control will be difficult if this condition is maintained. This is difficult, and increases the heat generation temperature of the adsorption section, increasing the risk of burning out the activated carbon as an adsorbent.

The solvent that was adsorbed during the adsorption process is desorbed from the adsorbent due to the resistance heat generation of the adsorbent itself.

In this way, this adsorbent adsorbs the solvent chlorofluorocarbons when electricity is not applied, and when electricity is applied, the temperature increases and the fluorocarbons are desorbed. Therefore, the solvent recovery device according to the present invention does not need to use steam to desorb the solvent.

On the other hand, in the solvent recovery device according to the present invention, first,
The solvent-containing gas is caused to flow through the adsorption tower by the solvent-containing gas flow means. Then, the solvent in the solvent-containing gas is adsorbed by the adsorbent in the adsorption tower to obtain clean gas.

Next, before the adsorption capacity of the adsorbent is saturated, the flow of the solvent-containing gas is stopped by the selection means, and instead, the electricity is applied to the adsorbent by the energization heating means to generate heat, and the temperature of the adsorbent is raised. , the inside of the adsorption tower is evacuated by an exhaust means. As a result, the solvent is desorbed from the adsorbent in the adsorption tower (Tm theory), and the exhaust gas containing the solvent at a temperature of 1°C is led to the condensing means and cooled, and the solvent in the exhaust gas condenses and becomes a liquid. It will be collected.

[Embodiments] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

Table 1 shows adsorbents according to examples of the present invention along with comparative examples thereof.

Note that the honeycomb molded bodies of Examples 1 and 2 and Comparative Example 2 used a non-conductive substance as a binder component, and the honeycomb molded body of Comparative Example 1 used activated carbon powder.

As described above, in the honeycomb formed body of Comparative Example 1, the binder component of the activated carbon is also a carbon material, so that ff1ffi of the non-conductive substance can be considered to be substantially zero.

Table 1 and FIG. 2 are graphs showing the actual temperature rise in the adsorbents of Examples 1 and 2.

FIG. 2 is a graph showing the temperature increase characteristics of the adsorbent, with the horizontal axis representing the current application time and the vertical axis representing the temperature of the adsorbent. An example of this adsorbent is clay material in activated carbon of 15.3 to 24.
It contains 8% by weight. In the figure, . represents non-conductive material (impurity) at 15.3% by weight, O represents 18.7% by weight, and Δ represents 2% by weight.
This is for an adsorbent containing 1.9% by weight and 24.8% by weight.

As shown in FIG. 2, when the content of the non-conductive material is as described above, the heating time to approximately e o 'c is 2.
Within minutes, the temperature of the adsorbent rises extremely quickly, and therefore, the desorption of the solvent begins immediately after the start of energization.

In the case of Comparative Example 1 shown in Table 1, the resistance value is small, so
In order to obtain the required amount of resistance heat generation, it is necessary to increase the current density, which makes it difficult to ensure uniformity of the current density distribution, and the contact resistance at the contact part with the electrode is excessive. It is difficult to put it into practical use because heat generation increases at the contact part.Also, in the case of Comparative Example 2, the resistance value is large, so the specified amount of heat generation cannot be obtained unless a high voltage is applied. It is not practical as a material.

FIG. 3 is a block diagram showing a solvent recovery device according to an embodiment of the present invention. The type of solvent is Freon (Freon 113).

Inside the adsorption tower 1, an adsorbent 2 formed into a honeycomb shape is housed. This adsorbent 2 contains activated carbon as a main component and 20% by weight of a non-conductive substance consisting of kaolin, which is a type of clay material, and metrose, which is a type of organic material.

An adsorbent having such a composition has sufficient adsorption ability as a fluorocarbon adsorbent. Also, its resistance value is 5.
Since it is 2×10ΩφC■, the temperature rises sufficiently quickly by energization.

A power source 3 is connected to the adsorbent 2, and a switch 4 is interposed between the adsorbent 2 and the power source 3. As a result, when the switch 4 is turned on, power is supplied to the adsorbent 2 from the power supply 3, and the adsorbent 2 itself generates heat through resistance.

In addition, air containing fluorocarbons is supplied into the adsorption tower 1 via piping 8, and this air containing fluorocarbons is supplied to the adsorbent 2 in the adsorption tower 1.
The fluorocarbons are adsorbed and removed. The obtained clean gas is discharged from the adsorption tower 1 to the atmosphere through the pipe 11.

A blower 5 is installed in the piping 9 to feed air containing fluorocarbons to the adsorption tower 1, and the piping 9,
11 is provided with on-off valves 10 and 12, respectively, to control the supply and discharge of gas to and from the adsorption tower 1, respectively.

Further, a pipe 13 is also connected to the gas outlet of the adsorption tower 1 , and the exhaust gas from the adsorption tower 1 is supplied to the condenser 7 via the vacuum pump 6 through the pipe 13 . That is, the vacuum pump 6 vacuums the inside of the adsorption tower 1 and sends the exhaust gas from the adsorption tower 1 to the condenser 7. Note that the piping 13 is provided with an on-off valve 14 that controls suction within the adsorption tower 1 .

Cooling water is allowed to flow through the condenser 7, and the gas fed into the condenser 7 is cooled in the condenser 7, and the fluorocarbons and moisture in the gas are condensed and become liquid. . This liquid is sent to the separator 8 via piping 16 and separated into water and fluorocarbon liquid by specific gravity, and the fluorocarbon liquid is stored in a storage tank 8.
It is collected in a.

In the fluorocarbon recovery apparatus configured as described above, first, the on-off valves 10 and 12 are opened, the on-off valve 14 is closed, and air containing fluorocarbons is supplied to the adsorption tower 1 by the blower 5. Also,
Switch 4 is turned off.

Then, the adsorbent 2 at room temperature adsorbs fluorocarbons in the fluorocarbon-containing air, and clean gas from which fluorocarbons have been removed is discharged from the adsorption tower 1. This clean gas is diffused into the atmosphere via piping 11.

After a predetermined period of time has passed and the adsorption capacity of the adsorbent 2 made of a honeycomb molded body is saturated, or just before saturation, the on-off valve 10 is closed to stop the supply of fluorocarbon-containing air, and the on-off valve 12 is closed, opened and closed. Open valve 14.

Then, switch 4 is turned on. Then, the adsorbent 2 of the honeycomb molded body is supplied with electricity from the power source 3, generates resistance heat, and is heated by electricity to a predetermined temperature.

As a result, the fluorocarbons that were adsorbed on the adsorbent 2 in the aforementioned adsorption process are desorbed, and the air in the adsorption tower 1 containing a high concentration of released fluorocarbons is sucked by the pump θ and supplied to the condenser 7. Ru. The exhaust gas from the adsorption tower 1 is cooled in the condenser 7, and the fluorocarbons and water are condensed to form a liquid. This liquid is sent to the separator 8 and separated into water and fluorocarbon liquid, and the fluorocarbon liquid is collected in the tank 8a.

Next, after a predetermined period of time has elapsed and the desorption process of the adsorbent 2 is completed, the on-off valves 10 and 12 are opened, the on-off valve 14 is closed, and the adsorption process is started again. In this way, by alternately performing the adsorption step and the desorption step, fluorocarbons are recovered from the fluorocarbon-containing air.

In this embodiment, since steam is not used in the regeneration process for desorbing fluorocarbons from the adsorbent, various drawbacks of conventional fluorocarbon recovery devices associated with the use of steam can be overcome.

Moreover, by using the fluorocarbon adsorbent according to the present invention, the temperature can be rapidly raised by heating with electricity, so that the processing efficiency does not decrease. In addition, when regenerating the adsorbent using steam, the adsorbent is heated to approximately 100"C, but in this example, the inside of the adsorption tower 1 is heated using a vacuum pump θ (exhaust means). Since it is exhausted, the heating temperature only needs to be as low as about 60℃.For this reason,
The heating energy required for the adsorbent is low.

FIG. 4 is a block diagram showing a batch type fluorocarbon gas recovery apparatus according to another embodiment of the present invention. This fluorocarbon gas recovery apparatus has two adsorption towers, a first adsorption tower 2'1 to a second adsorption tower 22, and by alternately repeating a batch-type adsorption process and a desorption process, both adsorption towers 21, 22 This enables continuous fluorocarbon gas recovery processing.

Each adsorption tower 21, 22 is filled with the same adsorbent as in the first embodiment (
(not shown) is housed in the adsorbent, and each adsorbent is heated and controlled by electricity.

The fluorocarbon-containing air 23 is passed through the pipe 41 (
41a, 41b) to be branched and supplied to the adsorption tower 21.22. On-off valves 28 and 29 are installed in the pipes 41a and 41b, respectively.
29 controls the supply of fluorocarbon-containing air 23 to each adsorption tower 21 and 22.

Cooling air is supplied to piping 42 (42a, 42 by blower 27b).
b) is drawn off from the adsorption tower 21.22. And, on-off valves 30.31 are interposed in each of the pipes 42a and 42b, and these on-off valves 30.31 are connected to each adsorption tower 21.
．． Controls the suction of cooling air to 22.

Further, the carrier gas for regeneration is supplied through the pipe 43 (43a).

43b) to the adsorption towers 21 and 22, and the pipes 43a and 43b are each equipped with an on-off valve 3.
4.35 is interposed. The on-off valves 34 and 35 control the supply of carrier gas for regeneration to the adsorption towers 41 and 42, respectively. Further, the piping 43 is provided with a constant pressure valve 50, and carrier gas for regeneration can be supplied from outside the adsorption tower via the constant pressure valve 50 only when the adsorption tower 21 or 22 is sucked to a predetermined pressure or less. It looks like this.

On the other hand, pipes 44 are provided at the gas discharge ports of the adsorption towers 21 and 22, respectively.
a, 44b are connected, and these pipes 44a, 44b
are collectively connected to an exhaust air tank 44. Opening/closing valves 32 and 33 are installed in each of the pipes 44a and 44b to control the discharge of purified air 26 from the adsorption towers 21 and 22. Purified air 26 is released from the exhaust air tank 44 into the atmosphere.

Further, pipes 45a and 45b are connected to other gas discharge ports of the adsorption towers 41 and 42, respectively.
5b are arranged to gather at the pipe 45. and,
Each pipe 45a, 45b is provided with an on-off valve 38, 37, respectively, to control the discharge of the regenerated gas from each adsorption tower 21, 22. A vacuum pump 51 is provided in the pipe 45, and the vacuum pump 51 sucks the gas after regeneration. Further, a pipe 52 is provided on the outlet side of the vacuum pump 51 and connected to a condenser 38, and the regenerated gas is cooled by cooling water in the condenser 38 and liquefied. This liquid is sent to the water separator 39 via piping 46, and the water in the liquid and the fluorocarbon liquid are separated by the water separator 39. This fluorocarbon liquid is delivered to the storage tank 40 via piping 47 and stored therein. In addition, the non-condensed gas in the condenser 38 is collected in the recycle air tank 53 via the water separator 3θ, and is sent to the blower 27a via piping 54 in order to perform the adsorption action again.
A part of the gas is returned to the inlet of the gas tank, and a portion thereof is used as a carrier gas for regeneration via piping 43. Note that the piping 54 is provided with a flow rate regulating valve 55 in order to prevent the supply of recycled air more than necessary.

Next, the operation of the batch type fluorocarbon gas recovery apparatus according to the present embodiment configured as described above will be explained.

First, the adsorbent stored in the first adsorption tower 21 has been regenerated and is in an active state, and the adsorbent stored in the second adsorption tower 22 has been adsorbed and has sufficiently absorbed CFCs. Suppose that it is in a state of adsorption.

In this case, on-off valves 28 and 32 are opened, on-off valves 29 and 33 are closed, on and off valves 30 and 31 are closed, on and off valves 34 and 36 are closed, and on and off valves 35 and 37 are opened. Then, the fluorocarbon-containing air 23 is sent into the adsorption tower 21 via the pipe 41a by the blower 27a.

This fluorocarbon-containing air 23 passes through an adsorbent in the adsorption tower 21 to adsorb and remove the fluorocarbons, and then is discharged from the adsorption tower 21 as purified air 26 via an exhaust air tank 44 via a pipe 44a.

On the other hand, inside the adsorption tower 22, a pipe 45 is operated by a vacuum pump 51.
b, 45, and the adsorbent in the adsorption tower 22 is further supplied with electricity from a separately provided power source, generates resistance heat, and is electrically heated to a predetermined temperature. The temperature of the adsorbent in this adsorption tower 22 is controlled by measuring the temperature with a thermocouple provided in the adsorbent.

As a result, the temperature of the adsorption tower 22 is rapidly raised under reduced pressure to desorb fluorocarbons, and the exhaust gas containing a high concentration of fluorocarbons is supplied to the condenser 38.

Furthermore, when the inside of the adsorption tower 22 reaches a predetermined pressure or lower due to the suction action of the vacuum pump 51, the gas in the recycle air tank 53 is adsorbed from the pipe 43゜43b as a carrier gas for regeneration via the constant pressure valve 50 provided in the pipe 43. It is supplied to the column 22 to promote regeneration of the adsorbent within the adsorption column 22.

The fluorocarbon gas desorbed in this way is transferred to the condenser 38.
The water and fluorocarbon are condensed and liquefied, and the fluorocarbon liquid is separated from the water in the separator 8 and then collected in the storage sink 4-0. On the other hand, the gas component that has not been condensed in the condenser 38 is led from the separator 8 to the recycle air tank 53 via the pipe 56 and is used as the carrier gas for regeneration mentioned above. The fluorocarbon gas is collected again through the fluorocarbon gas-containing air blower 27a (returned to the inlet of the air blower 27a), thereby minimizing external discharge.

Next, after a certain period of time has elapsed, the on-off valves 28 and 32 remain open and the adsorption process in the first adsorption tower 21 is continued, while the on-off valves 3 and 32 remain open.
5.37 is closed to stop the desorption process of the second adsorption tower 22. Then, the on-off valves 31 and 33 are opened, and the cooling air that does not contain most or all of the fluorocarbons is pumped into the exhaust air tank 4.
4 to the adsorption tower 22, and this cooling air is supplied to the adsorption tower 22 from
The activated carbon or other adsorbent heated in the previous desorption process is cooled. The cooled gas discharged from the adsorption tower 22 is sucked by the cooling blower 27b via the pipes 42b and 42, and then returned to the exhaust air tank 44 again. In addition, in the case of a large-capacity machine, it is better to draw the air directly into the adsorption tower 22 from the outside and discharge it to the outside through the blower 27b. Further, during this cooling step, the electricity supply to the adsorbent in the adsorption tower 22 is stopped, and the purpose is to cool the adsorbent to a temperature range in which it can perform an adsorption action.

Then, after a certain period of time has elapsed, the un-close valve 29 is opened, and the on-off valve 3 is opened.
4.38 is opened, on-off valves 28.32 are closed, and on-off valves 31 are closed. . Note that the on-off valve 33 remains open, and the on-off valve 30,
35.37 remain closed.

As a result, the fluorocarbon-containing air 23 passes through the adsorbent of the second adsorption tower 22, and the fluorocarbons are adsorbed.

On the other hand, the fluorocarbons adsorbed on the first adsorbent are desorbed by electrically heating the first adsorption tower under reduced pressure.

The gas containing fluorocarbons and water is sent to a condenser 38 and a water separator 38, where a fluorocarbon liquid is recovered.

Then, after a certain period of time has passed, the on-off valve 34. ．． 3B is closed and on-off valves 30 and 32 are opened to supply cooling air to the first adsorption tower. Thereby, the first adsorption tower moves from the desorption process to the cooling process.

In this way, the adsorption process, desorption process and cooling process are carried out in one step.
Each on-off valve switches as a cycle, and the fluorocarbon-containing air 2
Collect the Freon liquid from 3. When the first adsorption tower 21 is in the adsorption process, the second adsorption tower 22 is in the desorption process and the cooling process, and when the second adsorption tower 22 is in the adsorption process, the first adsorption tower is in the adsorption process. 21 is carrying out the desorption process and the cooling process. As a result, fluorocarbon gas can be continuously recovered from the exhaust air. In addition, when the recovery of fluorocarbon gas does not need to be continuous, the adsorption, desorption, and cooling steps may be performed at fixed time intervals using only one adsorption tower. Furthermore, if the time for the adsorption step and the total time for the desorption and cooling steps do not match, three or more adsorption towers may be used. The number of towers is not limited to two, and a large number of three or more towers may be provided.

[Effects of the Invention] According to the present invention, an adsorbent is obtained that has excellent adsorption ability for solvents such as fluorocarbons, has a sufficiently high resistance value, and has a rapid temperature rise when heated with electricity. During desorption, fluorocarbons are adsorbed and desorbed (regenerated), and during desorption, fluorocarbons are desorbed by applying electricity to the adsorbent and being subjected to depressurization treatment, so steam is not used for fluorocarbon desorption (regeneration of the adsorbent). Various disadvantages associated with use can be eliminated. Further, in the present invention, since the inside of the adsorption tower is evacuated during desorption (regeneration), the required heating temperature of the adsorbent is low, so that the energy required for regeneration can be reduced.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the non-conductive substance content and the molded body specific resistance value for the adsorbent according to the example of the present invention, and Fig. 2 shows the temperature rise characteristics of the adsorbent of the example. Graph diagram, FIG. 3 is a block diagram showing a fluorocarbon recovery device according to an embodiment of the present invention, FIG. 4 is a block diagram showing a fluorocarbon recovery device according to another embodiment of the present invention, and FIG. 5 is a block diagram showing a fluorocarbon recovery device according to another embodiment of the present invention. It is a block diagram showing a collection device. 1.1a, lb; adsorption tower, 2; adsorbent, 3,3al
3b: Power supply, 4, 4a, 4b; Switch, 5; Blower, 6; Vacuum pump, 7; Condenser, 8; Separator

Claims (2)

[Claims] (1) The main component is activated carbon, and the non-conductive substance is 10 to 2
A solvent adsorbent containing 5% by weight of a solvent adsorbent, characterized in that the molded body has a specific resistance value of 1.0×10 to 1.2×10^2 Ω·cm. (2) an adsorption tower containing the solvent adsorbent according to claim 1; a solvent-containing gas flow means for passing a solvent-containing gas through the adsorption tower to obtain clean gas; and electrically heating the solvent adsorbent. an energizing heating means for energizing the adsorption tower, an exhaust means for evacuating the interior of the adsorption tower, a condensing means for cooling the exhaust gas from the adsorption tower and condensing the solvent, and supplying and heating the solvent-containing gas to the adsorption tower. 1. A solvent recovery device comprising: a selection means for selectively selecting between exhaust and exhaust.