Apparatus for reclaiming and purifying chlorinated fluorocarbons

The invention is a device for recovering contaminated chlorinated fluorocarbons (CFCs) from refrigeration apparatus, and purifying them for reuse. The CFC can be received in either vapor or liquid state, and is distilled and purified first in vapor state. The vapor is then superheated, compressed and condensed to a liquid state and is further purified in the liquid state. Heat of the condensed liquid stream is applied to help vaporize incoming CFC to heat the vapor so as to prevent recondensation, and to superheat the vapor prior to compression.

FIELD OF THE INVENTION 
This invention relates to the recovery and purification of old or 
contaminated chlorinated fluorocarbons (CFCs) from refrigeration units and 
the like. 
BACKGROUND OF THE INVENTION 
For many years CFCs, of which DuPont's "Freon" is a well known commercial 
brand, have been the standard heat transfer media in refrigeration units, 
air conditioners, heat pumps, and the like. The reason for their wide 
spread use is that CFCs are stable and nonflammable, boil and condense in 
a useful temperature and pressure range, and were believed relatively 
inert and free of harmful side affects. Recently, however, a serious 
impact on the ozone layer of CFCs released into the atmosphere has been 
discovered, and it is now necessary to avoid open air release of CFCs from 
equipment which contains them. In the normal use of CFC-containing 
equipment, the CFC is, of course, constantly recycled and is not released 
to the atmosphere. However, over time the CFC gradually becomes 
contaminated in the equipment and loses its effectiveness. The common 
contaminants include water, air, compressor oil, hydrochloric acid, waxes, 
varnishes, and the like. Such contamination accelerates the rate of 
breakdown of the CFC, because it increases compressor operating 
temperature. Moreover, prolonged operation at higher temperatures can 
cause compressor or compressor drive failure. 
For many years it was common practice in the industry simply to release 
contaminated CFC to the atmosphere. Now, however, that is no longer 
acceptable practice; nor is it responsible to abandon CFC containing 
equipment because it would eventually leak out. It thus is becoming 
increasingly desirable to service CFC containing units to purify the CFC 
in them or replace it with pure CFC in a manner which prevents any loss to 
the atmosphere or the environment. 
THE PRIOR ART 
While different types of apparatus have been proposed for removing CFC from 
existing units and purifying it for replacement or reuse, such equipment 
has been limited in application, inefficient in use, and does not 
sufficiently avoid loss of CFC. Some previous apparatus was adapted to 
receive CFC only in the vapor phase or in the liquid phase, but not both, 
and thus was of limited utility. In other apparatus, CFC was not fully 
recovered from the old unit, and a portion was lost to atmosphere; and/or 
purification was relatively poor. Even an impurity level of as little as 
1% can significantly impair the heat exchange capabilities of the CFC in a 
given piece of equipment and shorten its life span. Moreover, the act of 
recovery of itself can impart some impurities to the CFC, for example, 
compressor oil, which previous apparatus has neglected to remove. 
BRIEF DESCRIPTION 
This invention provides a highly efficient apparatus which can be attached 
to a unit containing old or contaminated CFC for removing and purifying 
substantially all the CFC in the old unit, whether in liquid form, vapor 
form, or partly in each, and for purifying the CFC to a high level of 
purity. Such recovery and purification are achieved without release of any 
CFC to the atmosphere. The apparatus may be connected "on line" to an 
existing unit to purify the CFC of that unit, or the recovered purified 
CFC may be delivered to a storage container for reuse or resale. Tests of 
material so purified have shown it to be as pure or even purer than 
commercially available new CFC. 
In the preferred embodiment of the present invention, the contaminated CFC 
is withdrawn from the old unit into the apparatus of the invention, in 
which it is first distilled to convert it all to a vapor state rather than 
merely expanding it by pressure reduction. It is first purified in the 
vapor phase by removing entrained liquid droplets, water and vapor-phase 
contaminants. The vapor is then superheated and compressed. Any compressor 
oil which has become admixed with the compressed vapor is removed, and 
noncondensable gases such as air are separated from the compressed vapor. 
The vapor is then condensed; and the condensed, partly purified liquid CFC 
is then further purified by removing water and/or other liquid 
contaminants. The CFC is returned to the unit from which it was removed, 
or is sent to a separate container for reuse or disposal. 
The apparatus minimizes the total expenditure of energy in the purification 
process. In part this is achieved by initially converting the received CFC 
to the vapor phase and then purifying the CFC as vapor, before compressing 
and condensing it, then further purifying it in the liquid phase. 
Moreover, the initial distillation is accomplished with heat added from 
warm, previously compressed and condensed liquid purified CFC. The vapor, 
once obtained, is further heated by warm recondensed liquid while being 
purified; and the vapor is superheated prior to compression by heat 
extracted in condensation, that is, without supplying heat energy from an 
outside source. A significant advantage is gained by superheating the 
vapor, i.e., heating it above its saturation point, prior to compressing 
it. Superheating the vapor before compressing it facilitates the 
extraction of non-condensable gases after compression. 
Once condensed the liquid CFCs are cooled with ambient air and by loss of 
heat to vaporize incoming liquid CFC. The apparatus does not require the 
use of artificial cooling (other than a fan) to remove the heat from the 
hot compressed gas in order to condense it. The purified CFC is delivered 
to a final outlet at nearly ambient temperature and pressure.

The present apparatus may be and preferably is constructed as a 
self-contained portable package 5 which can be moved as needed to a site 
to remove CFC from an existing unit or device 10. Device 10 may be a 
refrigeration unit, a chiller, an air conditioner, a heat pump or the 
like. It is contemplated that the apparatus 5 of this invention may be 
connected to an old unit 10 (for example, to the inlet or outlet of its 
compressor 11), as needed to purge the old unit and to purify the CFC 
removed from it. Where the purified CFC is to be returned to unit 10 being 
serviced, that unit may continue to operate during the actual purification 
by shunting liquid CFC from the old unit through the apparatus 5, and 
returning it to the same liquid line. 
Apparatus 5 is adapted to receive the contaminated CFC whether it is in 
liquid state, vapor state, or portions are in both states, through an 
inlet line 15 having a manual shut-off valve 16. From valve 16 the liquid 
or vapor from the incoming material flows via line 17 through a pressure 
regulating valve 18 which prevents the entering pressure from exceeding a 
desired maximum, e.g., about 30 psig when CFC 12 is to be processed. A 
line 19 communicates from valve 18 to a still 20 (shown in more detail in 
FIG. 2). Still 20 is heated in part by a source of energy from outside the 
apparatus, such as an electric heater 21, and vaporizes liquid CFC in its 
distillation chamber 22 (see FIG. 2). The distillation separates and 
leaves behind oils, liquid acids, water, particulates, varnishes, and 
waxes. The still temperature should be less than 100.degree. F., and well 
above 32.degree. F., in order to prevent contaminate water from boiling or 
freezing. Depending on ambient temperature, the still chamber temperature 
for vaporizing CFC 12 may be about 40.degree. F. Distillation chamber 22 
contains a tubular heating coil 23, as subsequently described. Any liquid 
which cannot be vaporized accumulates at the bottom of the chamber 22 and 
can be removed through a still bottoms line 25. The distillation separates 
the CFC from the non-vaporizing contaminants, whereas expansion (i.e., 
vaporizing through a restricted orifice or metering device) permits the 
contaminants largely to carry over. The vaporized gas (which may contain 
entrained liquid droplets) leaves chamber 22 of still 20 via line 24 which 
communicates with a liquid eliminator 27 (see FIG. 3). Liquid eliminator 
27 has an upright internal chamber 28, into which line 24 extends as a 
downturned U having an outlet 29 in chamber 28. An outlet line 31 extends 
from the top of chamber 28. Liquid droplets entrained with vapor entering 
chamber 28 from line 24 lose velocity on exiting from outlet 29 into 
chamber 28 and settle by gravity to the chamber bottom while the vapor 
exits upwardly through line 31. Liquid in chamber 28 can migrate back to 
still chamber 20 through line 24, to be reheated and vaporized or drained 
off via line 25. 
Line 31 carries the vapor through a sight glass 32 wherein the presence of 
any remaining liquid can be observed, to a pressure gauge 33 and into a 
vapor drier or separator designated generally by 35. The vapor drier 
continues the purification and drying of the vapor (which began in still 
20 and continued in liquid eliminator 27), and traps any residual 
condensable liquid left at this point. The drier has an internal chamber 
which contains a vapor porous plug core of an absorptive medium such as 
activated charcoal, and is effective to absorb water, acids (such as 
hydrochloric acid, etc.) contained in the vapor in line 31. One example of 
a suitable commercially available device for this purpose is sold by 
Sporlan Valve Co., St. Louis, Missouri, under the brand name "Catchall" 
molded porous core filter-drier. Any liquid which accumulates in the 
chamber of vapor drier 35 drains by gravity past a sight glass 46 and can 
either be returned to still chamber 22 via line 25 or removed and disposed 
of separately via outlet 52. 
From drier 35 the vapor passes through a pressure regulator 37, thence by a 
line 38 to a superheater 40 which may be of the finned coil type and in 
which the vapor is further heated, to a temperature above its saturation 
point. The superheater is heated by the passage of air over it which has 
in turn been heated by flow over a hot condenser, as will be explained. 
From superheater 40 the CFC gas passes through a line 41, having a 
compressor inlet or low pressure gauge 42, into the inlet port 43 of a 
compressor 44. The oil level in the compressor crankcase is monitored by 
bi-level sight glasses 47 and 48, which permit monitoring the maximum high 
oil level and minimum low oil level so that appropriate adjustments can be 
made. 
From outlet port 49 of compressor 44, the compressed, further heated vapor 
flows via a line 50 which has pressure gauge 51, to an oil separator 54. 
The oil separator removes any oil droplets from the compressed superheated 
vapor and returns it to the sump of compressor 44 via an oil return line 
56 having a sight glass 57 and a oil filter 59. Oil separator 54 may be of 
a type known per se. 
From oil separator 54 the hot compressed gas flows via line 60 to a 
separator 61 for separating non-condensable gas. This separator has a 
vertically elongated chamber 62 having a height substantially greater than 
its diameter. The usually encountered non-condensable gases, such as air, 
mixed with the CFC are lighter than the CFC and therefore tend to rise to 
the top of chamber 62, from which they may be removed through a valve 63. 
The CFC vapor, which is heavier than common non-condensable impurities, 
remains near the bottom of chamber 62 and exits that chamber via line 64. 
A vapor bypass line 115 extends from line 64 to the chamber of vapor 
drier/separator 35. This line 115 includes a solenoid valve 116 and a 
pressure regulator 117, which when valve 116 is open maintains a 
predetermined pressure in line 118, as will be explained. 
Below the junction with line 115, line 64 leads to a condenser 65 wherein 
the CFC is circulated through a finned heat exchanger and is cooled in air 
to a temperature sufficiently low that the CFC condenses almost completely 
to liquid state. 
From condenser 65 the now mostly liquid CFC is passed via line 66 to a 
sub-cooler 67, which condenses any remaining CFC vapor and further cools 
the CFC to a temperature several degrees below its condensing temperature. 
For reference, the boiling points at atmospheric pressure of some of the 
common CFCs are: 
______________________________________ 
"Freon" 11 (CCl.sub.3 F) 
75.degree. 
F. 
"Freon" 12 (CCl.sub.2 F.sub.2) 
-22.degree. 
F. 
"Freon" 22 (CHClF.sub.2) 
-41.degree. 
F. 
"Freon" 500 (azeotrope) 
-28.degree. 
F. 
"Freon" 502 (azeotrope) 
-50.degree. 
C. 
______________________________________ 
As indicated in FIG. 1 by the dashed line around superheater 40, condenser 
65 and sub-cooler 67, those three elements are in heat exchanging 
relationship, that is, air passing over the coils of elements 67 and 65 is 
warmed by them, then passes over superheater 40 to heat the gas in it. So 
arranged, these three elements form what may be referred to as a "tri-coil 
assembly" 69. A multi-speed fan 68, the speed of which can be electrically 
adjusted, provides the air flow across the tri-coil assembly and may be 
thermostatically controlled so as to increase air circulation rate when 
additional cooling is needed at the condenser, which adds more heat to the 
superheater. The condensed CFC, now cooled substantially below the 
temperature at which it was condensed, flows via line 70 through a liquid 
sight glass 71 to a pressure regulating means 73, by which its pressure is 
maintained at a level sufficient to assure condensation downstream of the 
condenser. 
As already noted, different CFC compounds boil at different temperatures, 
and thus the apparatus must be set to maintain a pressure appropriate for 
the particular CFC being treated. (The particular CFC content is usually 
listed on each unit 10.) To quickly set the appropriate pressure, it is 
desirable to provide a pressure regulating means 73 which is preset to 
pressures appropriate for the common specific CFC. For that purpose I 
prefer to provide two or more individually selectable, pre-set separate 
pressure regulators, which are connected in parallel. In the embodiment 
shown two separate pressure regulators are provided in parallel, one of 
which, designated at 75, maintains a pre-set higher pressure than the 
second valve pressure regulator 76. Selection of one of the regulators 75, 
76 is controlled respectively by manually operated valves 77 and 78 at 
their inlet sides. Similarly, where a larger range of different types of 
CFCs might be encountered, three, four or more pressure regulators could 
be provided in parallel, each preset to maintain an appropriate pressure 
in line 82. 
From pressure regulating means 73 the liquid CFC is conducted via line 80 
to a liquid drier 81. This drier, which may be similar in principle to 
vapor drier 35, contains a plug or filter of material which will absorb 
any residual water, hydrochloric acid or other common contaminants of the 
CFC, but is adapted to treat liquid flow rather than the gaseous flow 
handled by drier 35. I have found excellent results are obtained by drying 
and partly purifying before compression, and then by further purifying the 
liquid after compression and condensation. 
From drier 81 the liquid flows via line 82 to a cooling coil 83 around the 
outside of vapor drier/separator 35. The purpose of coil 83 is to 
dissipate further heat from the liquid in line 82, by using it to preheat 
the vapor in element 35 (which is at much lower temperature) just prior to 
its entry into the superheater 40. 
It should be noted that a line 110 is connected from liquid line 82 just 
upstream of coil 83, through a solenoid 113 to a manifold distributor 111 
which leads to the chamber 22 of still 20. The manifold divides the flow 
of line 110 into several smaller streams, and directs it through capillary 
tubes to multiple injector ports 112 (see FIG. 2), into the still chamber 
22, in which the liquid streams are sprayed along the length of coil 23. 
This line 110 can be opened to selectively reinject a portion of the warm, 
already purified liquid CFC from line 82 back to the still. This has been 
found useful to provide cooling of still coil 23, when needed, as will be 
explained. Solenoid valve 113 is operated electrically in response to the 
temperature in line 86, so as to reinject liquid when the still chamber 
temperature is too high for adequate heat transfer from coil 23. 
From cooling coil 83 the liquid CFCs pass via line 85 into the coil 23 in 
chamber 22 of still 20. Here the liquid in the coil gives up heat to the 
incoming cooler liquid and vapor from line 19 and thus is further cooled. 
From coil 23 the liquid then flows via line 86 through a CFC purity 
monitor 88 which preferably includes a device for infrared scanning of the 
purified CFC (to test for impurities such as moisture, oil, waxes, resins, 
varnishes and particulates) and a pH sensor (to detect acid content). Such 
monitoring devices are known per se and are not the invention. Purity 
monitor 88 may be connected to automatically operate a visual and/or 
audible warning device, and/or to shut off the apparatus, if quality 
declines beyond a predetermined level. 
Downstream of monitor 88 the CFC liquid passes through a visual sight glass 
90 by which the operator of the system can visually make a final 
inspection of the purified CFC liquid before it leaves the apparatus. From 
sight glass 90 the purified liquid flows via line 91 through a flow 
controller or throttling means 93, shown in preferred embodiment in FIG. 
4. The purpose of this device is to reduce both the pressure and the flow 
rate of the liquid, without heat gain and without permitting the liquid to 
expand sufficiently that vaporization occurs. In a preferred form of flow 
controller 93, two long coils 94, 95 of small diameter tubing, for example 
six feet long and 3/32" I.D, are separated by back-to-back needle valves 
at 96. The needle valves 96 do not function as a metering device, but 
rather as restrictors to reduce the flow rate. The pressure drops across 
them is insufficient to permit vaporization. Flow controller 93 is 
preferably in an insulated container 120, so that it allows no heat gain. 
It thus reduces the rate of flow of, and dissipates pressure in, the 
liquid without forming much vapor; and any vapor which is formed in the 
needle valve 96 is soon cooled and reconverted to liquid in coil 95. 
From flow controller 93, the liquid CFC flows via lines 97 and 98, solenoid 
valve 99, and a manual valve 100, to a tank or other receiver 101. 
Solenoid valve 99 may be operated electrically so that if for any reason 
the system fails to function properly or stops, the solenoid valve closes 
in order to prevent reverse flow of CFC from receiver 101 back into the 
apparatus. If the apparatus is being operated manually, the solenoid valve 
99 is closed (deenergized) and the transfer process is controlled through 
a hand valve 102 in a bypass line 103. 
Operation 
To start operation, after apparatus 5 has been connected to a unit 10 to be 
serviced, still chamber electric heater 21 is energized and either the 
high or the low pressure control valve 77 or 78 is opened, thereby opening 
a path to which ever pressure control valve 75 or 76 is set appropriately 
for the particular CFC to be treated. Compressor 44 is started. Fan 68 may 
initially be run at slow speed, and is switched to higher speed when 
greater cooling is needed at the tri-coil assembly 69. The contaminated 
CFC enters the apparatus through valve 16 and passes through pressure 
regulating valve 18 which regulates the pressure at the entrance to still 
chamber 22 at a predetermined level appropriate for the particular CFC 
being processed. The pressure established by valve 18 is selected (e.g. 30 
psi for CFC 12) to provide ample time for liquid CFC to be vaporized. This 
prevents still 20 from receiving CFC liquid too quickly, which would slow 
the distillation process and could cause contaminates to be flushed out of 
chamber 22, instead of remaining in the bottom. The pressure established 
keeps the chamber above 32.degree. F, to prevent freeze up, which would 
make separation of contaminates difficult. Heating of chamber 22 vaporizes 
any CFC liquid so as to leave behind most of the oils, liquid acids, 
water, particulates, varnishes and waxes. Liquid droplets are trapped in 
the liquid elimination chamber 27 and either revaporize or migrate back 
into chamber 22. The vapor passes to vapor drier/separator 35 wherein it 
is cleaned and dried, and wherein any residual liquid is separated and 
allowed to return back to still chamber 22 through lines 45 and 25. Return 
of residual liquid to the still takes place because chamber 22 and 
eliminator 35 are under the same pressure. Also, chamber 35 is preferably 
located at a higher elevation than chamber 22 so that gravity will assist 
the transfer back. When liquid transfers back to still chamber 22 it is 
either vaporized or, if not vaporized, collects in the bottom and can be 
drained off via line 25 through outlet 52 to a contaminant tank (not 
shown) for safe disposal. The level of the unvaporized liquid in the still 
can be monitored at sight glass 46. 
After the CFC has been cleaned and dried in vapor drier/separator 35, it 
passes through pressure regulating valve 37 which establishes a 
predetermined pressure in outlet line 38, from which the CFC vapor enters 
superheater 40 of the tri-coil assembly which, as already noted, heats it 
above its saturation point. The superheated vapor is then compressed by 
compressor 44. 
If the condenser discharge pressure, measured at gauge 51, is above the 
condensing pressure for the particular CFC at the operating temperature, 
this indicates the presence of non-condensable contaminants which should 
be eliminated. For example, from the standard table of condensing 
pressure/temperature relationships for CFC 12, at 84.degree. F., its 
condensation pressure is 90 psig. A condenser discharge pressure of 100 
psi would therefore indicate non-condensable gases. Such gases are 
typically lighter than CFC and can be eliminated by purging them at the 
highest point on the discharge side of the compressor. They can be 
eliminated by chemical neutralization or captured in a container for safe 
disposal so that they are not discharged into the atmosphere. 
The high pressure bypass line 115, which tees from non-condensable gas 
separation chamber outlet line 64, is used when the apparatus is started 
in order to prevent the compressor from pulling a vacuum upstream of its 
inlet port 43. When the pressure in the chamber of vapor drier 35 begins 
to drop, pressure regulating valve 117 opens and admits high pressure into 
vapor drier 35, to keep the system from going into a vacuum. If a final 
pump out of the unit 10 to be purged is needed, valve 116 can be 
de-energized and a vacuum obtained in line 15. 
The CFC vapor from line 64 enters condenser 65 as a high pressure/high 
temperature vapor. Ambient air removes heat from the coil of condenser 65, 
causing the high temperature gas flowing through the coil to change state 
at its saturation point and condense into a liquid. The CFC thus condensed 
enters the coil of sub-cooler 67 where further condensing and sub-cooling 
takes place, insuring a "solid" liquid CFC column in line 70. This flow 
can be monitored at the contaminant sight glass 71, which acts as another 
monitoring point. The sight glass indicates any moisture or acid content 
(which will cause a color change in the window material of the sight 
glass) and thereby alerts the system operator that the drier/separator 
chamber 35 has lost efficiency and that its contaminant removal core must 
be changed. By using either high pressure selector valve 77 or low 
pressure selector valve 78, depending on what type of CFC is being 
recaptured, liquid CFC is maintained at a constant predetermined 
condensing pressure by valve 76 or 76. 
A further stage of CFC purification takes place in the liquid drier 81. Any 
remaining (or added) contaminants are removed at this point. The CFC 
leaves liquid drier chamber and flows through line 82 to cooling coil 83 
around vapor drier/separator 35, where it gives up some of its heat to 
vapor in that drier, so that CFC vapor from the still does not recondense 
in the drier. From cooling coil 83 the liquid then passes through the 
internal heat exchange coil 23, previously described, in still chamber 22. 
This actual length of the tubing in chamber 22 may for example be 32 feet 
long, but it may be coiled into a 16 inch long, five inch diameter spiral. 
This coil carries the warm high pressure purified CFC liquid, which must 
be cooled to lose the rest of its heat before transfer into the receiving 
vessel 101. When filling a storage cylinder with warm CFC, the pressure of 
the cylinder and the pressure of the system might equalize which would 
cause transfer to stop. Therefore, it is desirable to provide means for 
releasing further heat at this point. Moreover, the released heat 
supplements the electric or other external heater 21, and thereby speeds 
up the distillation process. This is especially useful if still chamber 22 
is receiving a large quantity of cool, contaminated in-flowing CFC. (If 
the " finished" purified CFC liquid were being transferred back into unit 
10, such elimination of added heat may not always be necessary.) 
During high ambient temperatures, or when the contaminated CFC vapor 
entering still chamber 22 is in a vapor state rather than a liquid state, 
additional cooling is desirable for coil 23 to dissipate heat from it. For 
this purpose I have discovered that a portion of the purified liquid CFC 
can be taken from liquid drier output line 82 via line 110 and injected 
back into still chamber 22, and revaporized. Up to roughly 20% of the 
liquid CFC available in line 82 may be used in the still reinjection 
circuit. As the reinjected vaporizing liquid cools the liquid CFC in still 
coil 23, the process speeds up because as the liquid leaving the system 
and entering the receiver 101 cools the latter, its pressure is reduced 
and the flow to it is thereby promoted. As cylinder 101 chills, solenoid 
valve 113 can be cycled open and closed as needed. For this purpose 
solenoid valve 113 may be automatically controlled by a temperature sensor 
on line 86; or valve 113 can be operated manually. 
When the end of the cleaning and purifying process is nearing, liquid 
injection circuit solenoid valve 113 is de-energized and closed so that 
the contaminated unit 10 can be completely evacuated and the system will 
drain itself of almost all of its purified CFC, except up to about one 
pound by weight. This final amount can be pulled out onto an empty 
cylinder. The purge has then been completed and the apparatus can be used 
to clean and purify another batch of contaminated CFC, even if of 
different type. 
Condensing temperatures of about 80.degree. to 90.degree. F. are desirable. 
Regardless of which particular CFC is being processed, the system 
temperatures and condensing temperatures remain about the same; it is the 
pressures which vary. For purposes of illustration, as an example of how 
and where temperatures drop after compression, the temperatures at certain 
points in the apparatus during the processing of the common CFCs may be 
approximately as follows: 
______________________________________ 
Line 64 120.degree.-160.degree. F. 
Condenser 65 84.degree. 
Supercooler 67 79.degree. 
Line 82 79.degree. 
Line 85 68.degree. 
Line 91 58.degree. 
Line 97 55.degree. 
Receiver 101 55.degree. 
______________________________________ 
As previously indicated, the pressures vary with the CFC being purified; 
for CFC 12 the condensing pressure at 90.degree. F. is 100 psig, but for 
CFC 22 at the same temperature, the condensing pressure is much higher, 
about 168 psig. 
From the foregoing it can be observed that the apparatus first converts any 
incoming CFC liquid to vapor, then purifies the vapor in a first stage; 
the vapor is then superheated, compressed, condensed and returned to 
liquid state, and is then further purified in a second stage. I have found 
it much more effective to purify first vapor, then liquid in this manner, 
than to purify CFC liquid first. It can further be noted that the vapor is 
purified prior to compression and the liquid materials are purified after 
compression and condensation. Further, it can be seen that in the 
preferred embodiment there are several stages of removing heat from the 
condensed liquid, including condenser 65, sub-cooler 67, cooling coil 83 
around the vapor drier/separator 35, the coil 23 in still 20, and finally, 
flow controller 93. 
Tests have shown that badly contaminated CFC 12 can be purified by this 
apparatus to a purity equal to 99.91% that of new and unused CFC 12. The 
remaining impurity content was largely oil, which would be quite 
acceptable.