JP2001252632A - Removal of harmful contaminant from porous material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of removing harmful contaminants from porous materials, more specifically, a technique of removing PCB from porous materials, such as timber, paper ands polymer films to be used for manufacture of electric apparatus. SOLUTION: The method for removing the harmful contaminants from the porous materials comprises (a) a step of putting the porous materials into a drum having a horizontal axis, (b) a step of putting a liquid solvent to the harmful contaminants in the drum, (c) a step for rotating the drum around its horizontal axis for the time sufficient for mixing of the prescribed amount of the harmful contaminants with the solvent, and (d) a step of removing the fluid solvent from the drum thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to the removal of contaminants from porous materials, and more particularly to techniques for removing PCBs from porous materials such as wood, paper, and polymer membranes used in the manufacture of electrical equipment.

[0002] Electrically insulating fluids containing polychlorinated biphenyl (PCB) were once frequently used in electrical transformers, choke coils, and capacitors. However, such PCB-containing insulating fluids are physiologically and environmentally hazardous and include transformers, choke coils,
It has been found that capacitors should be replaced with equipment that does not contain environmentally harmful insulating fluids. Strict regulations are in place to eliminate unusable PCB containing insulating fluids as well as PCB saturated or PCB impregnated materials. For example, many jurisdictions have legal restrictions that only allow the destruction of organic waste in a licensed incinerator or storage in a licensed hazardous waste dump. To minimize such costly waste disposal, PCBs should be removed from electrical components until the components have a PCB content below the legal maximum allowed. Is desirable.

As known in the prior art, to reduce PCB compound levels in these materials to non-harmful levels, (a) at a temperature sufficient to remove absorbed PCB compounds, and Contacting the material containing the PCB compound with the extraction solvent for a time sufficient for that; and (b) separating the extraction solvent containing the PCB compound from the material.

[0004] US Patent No. 4,983,983 to Green et al.
No. 222, US Pat. No. 5,203, issued to Fesmire et al.
No. 359 and U.S. Pat. No. 49 issued to Bormann et al.
All of 88391 teaches agitating a material in a solvent to remove contaminants from the material. However, Green et al., Fesmire et al., And Bormann et al. All teach how to remove contaminants from non-porous materials, but teach that porous materials should be discarded.

[0005] The purification of solid porous insulating parts of electrical equipment is particularly difficult. Such insulation is made from insulating paper, insulating press board, resin bonded paper, resin bonded cloth, insulating wood, polypropylene or other polymer films or synthetic resin bonded compressed wood. Since such insulating parts are in contact with the insulating fluid in the appliance, the holes in these insulating parts are
Completely saturated with an insulating medium containing. Cleaning such an insulator with a solvent for PCB removal cannot substantially remove the insulating fluid from the interior of the insulating component, but only the surface of the insulating component. .

The prior art teaches a method of removing contaminants from porous materials contaminated with various substances, such as PCBs. U.S. Pat. No. 4,826,538 to Sanders et al teaches repeatedly injecting a cleaning solvent into a porous material, draining and stirring the porous material in solution until the desired level of decontamination is reached. States that the stirring includes rotating the porous material about its vertical axis in the solution. Also, U.S. Pat. No. 3,739,791 to Fry et al. Teaches a contaminant removal system for a variety of articles including rotating about a vertical axis.

The present invention is a method for removing toxic contaminants from a porous material, comprising: (a) placing the porous material in a drum having a horizontal axis; (b) toxic contaminants in the drum. Introducing a fluid solvent for the substance; (c) rotating the drum about its horizontal axis for a time sufficient for a predetermined amount of the toxic contaminant to mix with the solvent; and (d) subsequently removing the fluid solvent from the drum. It provides a method comprising the step of removing. This cycle can be repeated until the evaluation for the amount of toxic contaminant indicates that the desired amount of toxic contaminant has been obtained. Preferably, the contaminant is PCB. Preferably, the solvent is n-
It is selected from the group consisting of hexane, xylene, perchlorethylene, tetrachloroethylene, trichlorofluoroethane or any other solvent of the hydrofluoroethers. Preferably, the porous material is an electrically insulating material, earth,
It is selected from the group consisting of sand, natural polymer materials and synthetic polymer materials.

[0008] Preferred conditions for the present invention are to rotate at a rate of 1 to 10 revolutions per minute for 20 to 30 minutes and / or to bring the solvent from ambient temperature to 20 to 50 ° C below the boiling temperature of the solvent Heating to a temperature.

In a preferred embodiment, the present invention further contemplates placing the drum in a sealable container and sealing the container after step (a) and before step (b). . The invention further proposes an apparatus for implementing this preferred embodiment, the apparatus comprising a cart for loading said drum; having a wall and enclosing said cart in a sealable container. Sealable container having a door for filling; drainage pipe through the wall of the sealable container, removable to fill and discharge solvent from the drum Filling and discharging pipes that can be attached; including a motor for rotating the drum and a power generator for powering the motor. Preferably, the motor is located on the cart. Preferably, the power generator is located outside the sealable container.

In a preferred embodiment, the present invention further allows for a track for receiving and removing the cart in a sealable container. In a further preferred embodiment, the portion of the track extending beyond the interior of the container is configured to be removable.

[0011] The present inventors have developed a method and apparatus for solvent extraction for removing toxic contaminants from porous materials. Hereinafter, a case where the present invention is applied to removing contaminants from a porous insulator filled with PCB taken out of an electric capacitor or an electric transformer will be described in detail. However, it is to be understood that the present invention is applicable to a variety of contaminant removal methods and apparatus, and in particular, to the removal of contaminants from toxic-containing insulating fluids that are physiologically or environmentally hazardous. I want to be.

In the present invention, the solid material is agitated with the solvent by rotation about a horizontal axis to cause tumbling of the porous material in the solvent. This allows the solvent to be effectively and effectively mixed into the porous material. The solvent is then discharged. This cycle can be repeated many times.

The method uses a wheeled cart. Drums are loaded on this cart. This drum is rotatable by a hydraulic motor also mounted on the cart. The drum is loaded with the contaminated porous material in half the tank. The cart can be moved in a sealable container.
Filling and discharging tubes are connected to the drum and hydraulic lines are connected to the hydraulic motor. These filling, draining and hydraulic lines penetrate the walls of the sealed container. The solvent is then injected into the drum up to half of the drum, and hydraulic fluid is passed through the motor to rotate the drum and tumble mix the porous material in the solvent. The drum can be drained and refilled a number of times until the drained solvent is analyzed and indicates that the contaminant level has been reduced to the desired level. After the solvent has been drained, the porous material is subjected to a drying step. At the end of the drying step, the line is disconnected and the container is opened. Wheels pull the cart from the container so that the washed material can be removed from the drum for disposal or possibly recycling.

"Porous material" as used herein
Denotes all materials that absorb and retain the toxic compounds considered here. For example, porous materials include various insulating materials, earth, sand, and natural and synthetic polymeric materials. Polymeric materials such as vinyl ester resins (eg, DERAKANE ^™ ), paper, cloth, plastic, etc.
What is usually coarsely divided, for example in a crushed form, is a preferred porous material in the present invention.

As used herein, "solvent" refers to all extraction solvents suitable for the toxic compounds contemplated herein, such as PCBs or similar compounds, including methylene chloride, chloroform, carbon tetrachloride, Includes trichloroethane, methylchloroform, tetrachloroethane, pentachloroethane, trichloroethylene, perchloroethylene, benzene, toluene, xylene, acetone, methyl ethyl ketone, hydrofluoroether or mixtures thereof.

"PCB" as used herein is:
All PCBs or PCB analogs are indicated, including, for example, polychlorinated biphenyls, hexachloroethane, hexachlorobutadiene, hexachlorobenzene or mixtures thereof.

As shown in FIG. 1, the apparatus of the present invention includes an autoclave or container 30 and a cart 20. Cart 20 includes a chamber 58 containing perforated basket 22.
Has a cart wall 21 which forms Basket 22
Has a suitable basket door 23 for loading and unloading of porous material. The basket door 23 can be secured in the closed position by the latch 56 when closed. Cart 20 includes cart solvent couplings 24 and 25
And a cart hydraulic coupling 26 (only one of the two is shown). Cart solvent discharge coupling 25 is connected to chamber 5 via pipe 54.
8 in fluid communication with the bottom. Cart hydraulic coupling 2
6 is in fluid communication with a hydraulic motor 28. A hydraulic motor 28 is in rotational and mechanical communication with the basket 22.

Couplings 40, 41, 42, 24, 2
5, 26 are preferably standard one inch (2.4 cm) quick-release couplings. This type of coupling is adapted to be immediately closed when the inlet and outlet valves are decoupled. The connection of the solvent line through the autoclave wall 31 or the cart wall 21 can be formed from black carbon steel tubing using threaded fittings and chemically resistant compounds as screw sealants. Below the solvent lines 32 and 34 near the couplings 40, 41, 24, 25, a spill pan can be placed to receive droplets that might come out during hose connection and disconnection. The bend of each line is rolled in this spill pan to provide for any leaks. A gear pump with pressure bypass (not shown) is used to transfer liquid in the contaminant removal system. Depending on the design and technology of this system, PCB line and P
Cross contamination with lines not containing CB is prevented.

The autoclave 30 has an autoclave wall 31, an autoclave door 38, and an autoclave opening 37. The autoclave opening 37 is
The size is suitable for loading and unloading. Autoclave door 38 is attached to autoclave 30 using hinges 39, and door 38 is suitable for sealing autoclave opening 37.

The autoclave 30 further has a plurality of hydraulic lines 36 and solvent lines 32 and 34 that penetrate the autoclave wall 31. Autoclave 3
Outside of the hydraulic line 36 is in communication with the hydraulic generator 80 of FIG. Similarly, outside the autoclave 30, the solvent supply line 32 is connected to the clean solvent holding tank 66 shown in FIG.
And the solvent discharge line 34 is in communication with the second solvent storage tank 70 of FIG. As shown in FIG. 1, inside the autoclave 30, the hydraulic line 36 terminates in a hydraulic line coupling 42,
The solvent lines 32 and 34 terminate at the solvent line couplings 40 and 41.

An autoclave track 52 extends to the autoclave opening 37, which facilitates moving the cart 20 into and out of the autoclave 30. When the removable track 50 is outside the autoclave 30 and the door 38 is open, the track and the autoclave track 52 can be aligned and used for introducing and unloading the cart 20. Detachable track 50
Can be removed to facilitate closing the door 38.

When the cart 20 is placed in the autoclave 30, the hydraulic line coupling 42 can be removably connected to the cart hydraulic line coupling 26, and the solvent discharge coupling 40 can be removably connected to the cart discharge coupling 25. Yes, and the solvent supply coupling 41 can be removably connected to the cart supply coupling 24. When they are connected, hydraulic line coupling 42 is in fluid communication with cart hydraulic line coupling 26, solvent discharge coupling 40 is in fluid communication with cart discharge coupling 25, and solvent supply coupling 41
Is in flow communication with the cart supply coupling 24.

In use with respect to FIGS. 1 and 2, the PCB
The porous material 62 contaminated with, for example, the PCB capacitor core insulation material is crushed by feeding to a shredder or crusher 60. After passing through the crusher 60, the contaminated material 62 is placed in a perforated metal basket 22 in the decontamination cart 20. Once the basket 22 has been loaded with the material, the cart 20 is placed in the autoclave 30. A solvent supply coupling 41 is connected to the cart supply coupling 24, a solvent discharge coupling 40 is connected to the cart discharge coupling 25, and a hydraulic line coupling 42 is connected to the cart hydraulic coupling 26, after which the hinge 39 The door 38 of the autoclave 30 is closed and sealed. The device is now ready for the start of the pollutant removal cycle.

A clean solvent 68, for example perchlorethylene, is pumped from the holding tank 66 through the solvent supply line 32 to the contaminant removal cart 20. After filling the desired volume of solvent 68, the hydraulic motor is started and the basket 22 begins to rotate. In a preferred embodiment, the volume of the solvent is sufficient to allow the level of the solvent to reach half the height of the basket 22. Because the basket 22 is perforated, the solvent flows through the basket 22 and is in free contact with the porous material. Mixing the porous material by rotating the basket 22 in a solvent increases the rate of contaminant removal from the material.

Once the PCB distribution in the contaminated core and the PCB distribution in the extraction solvent have reached equilibrium (eg, after mixing for 20 to 30 minutes), the rotation of the basket 22 is stopped and the solvent now contaminated with PCB is removed. Can be discharged. The PCB-contaminated solvent is then discharged to the solvent discharge line 3
4 to the second holding tank 70. The fresh solvent is then refilled into the decontamination vessel through the solvent supply line 32 and the basket rotation is started again. A sample 72 of the extraction solvent is collected and analyzed to check the extraction efficiency in the cycle. The PCB extraction process determines that the results for the extraction solvent sample 72 indicate that the removal of contaminants from the material is at the desired level (typically 50 ppm
) Is reached.

The extraction process can be accelerated by increasing the temperature of the extraction mixture. Any suitable means for supplying heat to the solvent extraction process can be used. In one embodiment, the autoclave unit 30
Includes an electric heater 44 which can heat the system to a desired level when the system is loaded with contaminant material and extraction solvent. In another embodiment, the hot solvent is directly delivered from the solvent recovery system to the cart 20.
Can be supplied inside.

When the removal of contaminants from the porous material is complete, the cart 20 can be drained and the decontaminated porous material 64 inside the basket 22 can be dried. The PCB-filled solvent can be purified and reused, for example, using a thin layer evaporator 74 as described below. That is, the solvent filled with PCB is supplied to the top of the evaporator 74. Gravity and the axis of rotation of the device allow for a uniform distribution of the contaminated solvent. As the hot fluid is supplied through the jacket of the evaporator, the solvent evaporates in the center of the device and moves upwards towards the condenser. This solvent vapor is collected at the bottom of the condenser and is periodically sent to a clean holding tank 66. The PCB rich fraction 78 is collected at the bottom of the evaporator 74 and is periodically pumped to a PCB storage tank 76. At the top of the condenser is mounted a vacuum pump (not shown) so that the evaporation system can operate at low pressure and low temperature.

[0028] The PCB contaminated solvent produced by the contaminant removal process is reclaimed and reused in the process. High level PCB liquid waste separated during regeneration of the decontamination solvent is discarded through any approved PCB destruction process.

The porous material in the cart 20 immersed in the solvent is preferably subjected to a drying step before opening the autoclave 30. To dry the porous material, heater 44 in autoclave 30 is activated and air is forced through autoclave 30 and solvent condensing unit 82 using blower 84. This can be done in a closed loop. The solvent collected in the condenser 82 is then stored in the holding tank 7.
Stored at zero. The drying process is continued until the recovery of solvent in the condenser has decreased to a few milliliters per minute, indicating that the amount of solvent remaining in the porous material is negligible.

When the drying process is completed, the autoclave door 38 is opened and the cart 20 is withdrawn from the autoclave 30. Once the cart 20 has been removed from the autoclave 30, the door 23 of the basket 22 is opened and a sample of the material is taken for analysis. Once the analysis confirms that the level of contaminant removal meets regulatory standards, the material is discharged from the system and declares that the contaminant has been removed. However, if the PCB level in the material is higher than the target, the cart 20 loaded with the material is returned into the autoclave 30 and the solvent extraction operation is extended. The solvent draining, drying, and analyzing operations are repeated until the target contaminant removal level for the porous material is achieved.

To determine the extraction efficiency of the method of the present invention, US Pat. No. 3540-B, PCB from porous material
Soxhlet extraction method for extraction (US EPA Method N
o.3540-B, Soxhlet Extraction Method for Extracting
PCB from Porous Materials). This ensures that the decontamination target for the decontaminated crushed porous material 64 is achieved. The Soxhlet method ensures intimate contact between the sample matrix and the extraction solvent, and allows the quantitative separation of PCBs and other water-insoluble organic compounds from solid samples. In summary, mixing the material sample with anhydrous sodium sulfate,
Place in thimble and extract in a Soxhlet extractor using a suitable solvent. After this, the extract is dried, concentrated (if necessary) and, if necessary, replaced with a solvent suitable for the subsequent cleaning and quantification steps. The particular cleaning operation used will depend on the nature of the sample to be analyzed and the goals of data quality for measurement. General guidelines for cleaning sample extracts are provided in US EPA Method 3600. The analysis can be performed using the US EPA Method 8081 Analytical Method.

[0032]

EXAMPLE This example illustrates the performance characteristics of the present invention in removing PCB from a capacitor insulator contaminated with PCB. Inserted things porous material: 738Kg contaminant removal solvent: 10000 kg (reproduced again be used by the batchwise) produced was porous material: 738Kg contaminant removal solvent: 9800Kg ^* Liquid PCB (unrecovered solvent): 150 Kg * In this example, the contaminant removal solvent was also used for spray cleaning non-porous materials.

As described above, the present invention provides a method for removing toxic contaminants from a porous material, the method of the present invention overcomes the disadvantages of the previously known methods, and reduces the PCB content. It allows easy and cost-effective removal of the insulating fluid from the pores of the insulator. In particular,
Contaminants are not only removed from areas close to the surface of the porous material, but also from deep areas within the porous material.

The present invention has significant advantages over the prior art, as there is no need to create solvent passages in liquid impermeable materials as in the prior art. Compared to the prior art, the material and the solvent mix dynamically and well, facilitating the transfer of toxic contaminants from the material to the solvent phase.

The present invention further achieves several other advantages over prior art methods. For example, according to the teachings of the prior art, a drum containing contaminated porous material is rotated about a vertical axis. Thus, in order for all of the contaminated material to come into contact with the cleaning solvent, the drum must be filled with solvent. In contrast, in the present invention, the solvent may be partially filled. The contaminated material will be repeatedly immersed in the solvent during tumble mixing. Second, as the materials are rotated in the drum around their vertical axis, they tend to move to the sides of the drum and stay there. This reduces the effective mixing of solvent and material. Some prior art methods address this problem by introducing a secondary agitation movement, a piston-like vertical movement. According to the invention, such a secondary stirring movement is not necessary. This is because as a result of tumbling of the material, the contaminated material always remains in motion. Therefore, as a further advantage over the prior art, the mechanical device can be simplified and the energy efficiency can be further improved.

The present invention is also superior to the prior art in using an autoclave and cart system. The apparatus of the present invention can perform a decontamination cycle, in practice a plurality of sequential decontamination cycles, in a sealed chamber, isolated from workers and other personnel and the environment outside the autoclave. . This is very advantageous for removing pollutants that are harmful both physiologically and environmentally.

The present invention also has advantages over the prior art in using carts. Although the device taught by the prior art includes a plurality of baskets, the baskets cannot be easily moved into and out of the sealed container, and the contaminated porous material can be easily transferred to another container when moved to another location. Can not be transferred to In contrast, according to the present invention,
The use of a cart and the use of removable solvent and hydraulic lines that penetrate the walls of the enclosure, so carts or drums containing contaminated material can be easily moved to another location and the contaminated material can be directly No need to carry.

Also, the use of carts and baskets allows the solvent to be quickly and efficiently separated from the material in the discharge process. It is desirable to separate as much solvent as possible at the end of each extraction step in order to reduce the number of extraction steps required to reach the target for contaminant removal.

It is also desirable to separate as much solvent as possible in order to reduce the time required to remove residual solvent from the solid material in the final drying step.

While the invention has been described with reference to a preferred embodiment, it will be understood that various modifications of the apparatus disclosed herein are within the scope of the invention.

[Brief description of the drawings]

FIG. 1 is a perspective view, partially broken away, of one embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a method of one embodiment of the present invention.

[Explanation of symbols]

 20 Cart 22 Basket 23 Basket Door 24 Cart Solvent Supply Coupling 25 Cart Solvent Discharge Coupling 26 Cart Hydraulic Coupling 28 Hydraulic Motor 30 Autoclave 32, 34 Solvent Line 36 Hydraulic Line 37 Autoclave Opening 38 Autoclave Door 40, 41 Solvent Line Coupling 42 Hydraulic Line Coupling 44 Heater 50 Removable Track 52 Autoclave Track 60 Shredder 62 Contaminated Porous Material 64 Contaminated Porous Material 66 Clean Solvent Reservoir 68 Clean Solvent 70 Second Reservoir 72 Sample 74 Thin layer evaporator 76 PCB storage tank 78 PCB concentrated fraction 80 Hydraulic generator 82 Condenser 84 Blower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01F 15/02 B01F 15/02 AC 15/06 15/06 Z B09B 3/00 ZAB B01D 1/22 Z 5/00 E // B01D 1/22 B09B 3/00 ZABZ 5/00 304Z (72) Inventor Blair F. Singh Canada. El 6 X 1 El 5 Ontario, Brampton, English Street 23 (72) Inventor Henry E. Kowalik Canada. El 7 R 3 X 5 Ontario, Burlington, Orchard Road 2211 (72) Inventor Alexander Zett. Murinaxic Canada. M9V 1tee9 on Tario, Toronto, Kendleton Drive 65 (72) Inventor Nobuyoshi Miura Canada. M9C5E2 Ontario, Etobicoke, Elmblock Crescent 96

Claims (23)

[Claims] 1. A method for removing toxic contaminants from a porous material, comprising: (a) placing the material in a drum having a horizontal axis; (b) placing the drum in a sealable container. Placing and sealing the container; (c) placing a fluid solvent for the toxic contaminant in the drum;
(D) rotating the drum about the horizontal axis for a time sufficient for the predetermined amount of the toxic contaminant to mix with the fluid solvent; and (e) then removing the fluid solvent from the drum. A method comprising the steps of: 2. The method of claim 1, wherein said contaminant is PCB. 3. The method of claim 2, wherein said solvent is a hydrofluoroether or a mixture of hydrofluoroethers. 4. The method of claim 3, wherein said solvent is selected from the group consisting of tetrachloroethylene, trichlorofluoroethane, or a mixture thereof. 5. The method according to claim 1, wherein the porous material is an electrically insulating material, earth,
The method of claim 1, wherein the method is selected from the group consisting of sand, natural polymeric materials and synthetic polymeric materials. 6. The porous material is selected from the group consisting of vinyl ester resin, paper, cloth, plastic, insulating paper, insulating press board, resin bonded paper, resin bonded cloth, insulating wood and synthetic resin bonded compressed wood. A method according to claim 5, wherein 7. The method according to claim 1, wherein the rotation is one rotation per minute and 10 rotations per minute.
The method according to claim 1, wherein the method is performed at a speed between rotations for 20 to 30 minutes. 8. The method of claim 1, further comprising the step of heating said solvent from ambient temperature to a final temperature between 20 ° C. and 50 ° C. below the boiling temperature of said solvent. 9. The method of claim 1, further comprising, after step (e), assessing the amount of toxic contaminants in the solvent removed from the drum. 10. After step (e), steps (b), (c), and (c) until the desired amount of toxic contaminant has been obtained as indicated by the evaluation of the amount of toxic contaminant.
The method of claim 7, further comprising repeating (d) and (e). 11. The method of claim 1, further comprising the step of crushing the material before placing the material in the drum. 12. The method of claim 1, further comprising, after step (e), treating the solvent in a thin layer evaporator to separate the solvent from the contaminants. 13. The method of claim 12, further comprising the step of reusing said treated solvent in said drum. 14. The method of claim 1, further comprising, after step (e), removing residual solvent from the material by evaporation in a closed loop. 15. An apparatus for removing toxic contaminants from a porous material, comprising: (i) a cart including a drum; (ii) a wall and containing the cart in a sealable container. (Iii) a filling tube and a discharge tube passing through the wall of the sealable container, for filling the drum with a solvent and discharging the solvent from the drum. An apparatus comprising: a filling tube and a discharge tube removably attachable to the drum; and (iv) a motor for rotating the drum and a power generator for powering the motor. 16. The apparatus of claim 15, wherein said motor is located on said cart. 17. The apparatus of claim 15, wherein said power generator is a hydraulic power generator. 18. The apparatus according to claim 15, wherein said hydraulic power generator is located outside said sealable container and power passes through said wall in a hydraulic line. 19. The apparatus of claim 15, further comprising a track for receiving the cart from the sealable container and for delivering the cart. 20. The apparatus of claim 19, wherein a portion of said track extending beyond the interior of said container is removable. 21. The apparatus of claim 15, wherein said drum comprises a perforated basket confined within a chamber. 22. The apparatus of claim 15, wherein said drum further comprises a removably securable drum door for loading said material. 23. (V) a heater for evaporating the solvent to a gas phase, wherein the heater is disposed in the sealable container; and (vi) condensing the gas phase by condensation. 16. The apparatus of claim 15, further comprising: a condenser for producing a condensed solvent; (vii) a blower for circulating the gas phase to the condenser; and (viii) a storage tank for collecting the condensed solvent. .