Note: Descriptions are shown in the official language in which they were submitted.
21~713~
Refri~erant Recovery and Recycling System
FIELD OF THE INVENTION
The present invention relates to a method of recovering and
5 recycling refrigerants such as chlorofluorocarbon compounds (CFCs)
from refrigeration and air conditioning devices.
The present invention also relates to an apparatus for recovering
and recycling refrigerants such as CFC compounds.
BACKGROUND OF THE INVENTION
Most modern refrigeration equipment employs one of several
organic solvent compositions, such as chlorofluorocarbon compounds
(CFCs), as a working fluid (refrigerant).
For various reasons, such as wearing of the seals in the
15 refrigeration equipment's compressor, the refrigerants in the equipment
may eventually become cont~min~te~l with dirt, oil and/or moisture.
These con~min~nt~ affect the efficiency of the equipment and may
eventually lead to damage of the compressor and other components in the
equipment. Thus, it is typically required that the refrigerant in the
20 equipment be replaced at intervals to avoid damage to the equipment and
to restore the equipment's overall efficiency. Also, in the event of a
failure of the equipment, it is typically required that the refrigerant be
removed from the equipment prior to servicing.
Previously, the most common method of removing the refrigerant
25 from the equipment was to vent the refrigerant into the atmosphere and
to replace it with virgin refrigerant as required. However, problems
exist with this method of removing the refrigerant.
The release of CFC compounds into the atmosphere results in the
depletion of the ozone layer therein. As the ozone layer is the principal
-2 -
filter in the atmosphere for removing the sun's ultraviolet radiation,
much concern has been expressed about its depletion as it is expected to
lead to many problems. For example, it is expected that an upturn in
related health problems such as skin cancer will occur. Accordingly,
5 many governments are passing legislation restricting or prohibiting the
use of and/or release of CFC compounds into the atmosphere. These
restrictions pose a serious problem to refrigeration equipment
manufacturers and servicers who no longer can release CFC-type
refrigerants into the atmosphere.
A second problem in regard of venting of refrigerants to the
atmosphere exists, albeit one with a lesser impact, is the fact that the
virgin refrigerant compounds required for replacement of vented
refrigerants are expensive and, in the case of CFCs, may be difficult to
obtain.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel
apparatus for recovering and recycling refrigerant compounds.
According to one aspect of the present invention there is provided
20 apparatus for recovering and recycling refrigerant compounds from
refrigeration equipment comprising: a separation unit for separating
refrigerant from cont~min~nt.~, said separation unit including means
operable to heat a mixture of liquid refrigerant and liquid cont~min~nts
to vaporize at least some of said liquid refrigerant and means to separate
25 suspended liquid cont~min~nt~ from gaseous refrigerant including means
to collect liquid cont~rnin~nt~; an expansion valve to vaporize liquid
refrigerant not vaporized in said separation unit; first valve means
~sl.~
-3 -
operable to connect said separation unit to said refrigeration equipment;
means to draw gaseous refrigerant from at least one of said separation
unit and said expansion valve and to pressurize said gaseous refrigerant,
said means to draw operable to create a reduced pressure in said
separation unit and said reduced pressure drawing liquid and/or gaseous
refrigerant and liquid cont~min~nt~ from said equipment to said
separation unit; means to remove collected cont~min~nt~ from said
separation unit; and second valve means operable to supply said
pressurized refrigerant to a storage vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
A pler~ d embodiment of the present invention will now be
described, by way of example only, with reference to the attached
figures wherein:
Figure 1 shows a schematic representation of a recovery and
recycling system in accordance with the present invention;
Figure 2 shows a cut-away view of a recovery and separation unit;
Figure 3 shows a perspective view of an embodiment of the
portable recovery and recycling system shown in Figure l;
Figure 4 shows the recovery and recycling system of Figure 1 in
use;
Figure 5 shows the path of refrigerant through the system of
Figure 1 during evacuation;
Figure 6 shows the path of refrigerant through the system of
Figure 1 during recovery and recycling;
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Figure 7 shows a schematic representation of another embodiment
of a recovery and recycling system in accordance with the present
invention;
Figure 8 shows a perspective view of the portable recovery and
recycling system shown in Figure 7;
Figure 9 shows a perspective view from the rear of the portable
recovery and recycling system shown in Figure 7;
Figure 10 shows the configuration of the recovery and recycling
system of Figure 7 in a first and second mode of operation;
Figure 11 shows the recovery and recycling system of Figure 7
during the first mode of operation;
Figure 12 shows the recovery and recycling system of Figure 7
during the second mode of operation;
Figure 13 shows the recovery and recycling system of Figure 7
configured for a third mode of operation;
Figure 14 shows the recovery and recycling system of Figure 7
during the third mode of operation; and
Figure 15 shows the recovery and recycling system of Figure 7
during a fourth of operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A schematic representation of a recovery and recycling system in
accordance with the present invention is indicated generally at 20 in
Figure 1. The system includes a recovery and separation unit 24, a
compressor 28, and a condenser 32. Recovery and separation unit 24 is
a pressure vessel suitable for cont~ining a vacuum and includes a
pressure relief valve 36, a level sensor 40 and a heating coil 44.
-5 -
Recovery and separation unit 24 also includes a product inlet 48, a
product outlet 52 and a con~min~nt outlet 56. Heating coil 44 is located
within recovery and separation unit 24 and is connected between an inlet
60 and an outlet 64 mounted thereon.
Product inlet 48 is connected to a product-in control solenoid
valve 68 which is in turn connected to a product-in control valve 72.
Control valve 72 is connected to a suitable pressure connector 76, such
as a female 1/4" connector.
Similarly, cont~min~nt outlet 56 is connected to a cont~min~nt-out
control valve 80 and a suitable drainage connector 84. Cont~min~nt-out
control valve 80 enables the draining of collected cont~min:~nt~ from
recovery and separation tank 24 as required.
Product outlet 52 is connected to the low pressure side of
compressor 28 and to one side of an evacuation solenoid valve 88. The
high pressure side of compressor 28 is connected to an evacuation
control valve 92 and to one side of a discharge solenoid valve 96.
Evacuation control valve 92 is connected to a suitable pressure connector
100 while the other side of discharge solenoid valve 96 is connected to
heating coil inlet 60.
The other side of evacuation solenoid valve 88 is connected to the
inlet of condenser 32 and to outlet 64 of heating coil 44. The outlet of
condenser 32 is connected to a product-out control valve 104, which is in
turn connected to a suitable pressure connector 108.
Figure 2 shows the presently preferred embodiment of recovery
and separation unit 24 in more detail. Unit 24 is an insulated, vertically
mounted four litre tank. As shown in the Figure, product inlet 48,
which is spaced from product outlet 52, includes a portion 49 which
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extends into the tank while product outlet 52 is mounted flush with the
top of the tank. As is also shown in the Figure, he~tin~ coil 44
comprises two coils of pressure line located adjacent the bottom of the
tank and cont~min~nt outlet 56 extends from the bottom of the tank.
This particular configuration of recovery and separation unit 24
has been found to provide the necessary performance characteristics, as
will be explained in more detail below, at a reasonable cost of
m~mlf~cture.
Compressor 28 may be any compressor for compressing
refrigerant as will be understood by those of skill in the art. In the
pl~r~ d embodiment, compressor 28 is a 280 CFM (16800 CFH) at 4.5
lb positive pressure compressor. Compressor 28 is capable of producing
a vacuum of 10 inches of mercury in recovery and separation unit 24 and
operates to allow system 20 to draw between 1.75 and 2.5 lbs of liquid
or vapour refrigerant per minute and 5 lbs per minute or more during
liquid lift.
Condenser 32 may be any suitable condenser for refrigerant as
will be understood by those of skill in the art. In the preferred
embodiment, condenser 32 is an air cooled 6000 BTUH capacity
condenser. As will be understood by those of skill in the art, an
electrically driven cooling fan (not shown) may be provided for use with
condenser 32, if required.
A ~;ullelllly plerell~d embodiment of the present invention is
indicated generally at 200 in Figure 3. As is shown, the prer~ d
embodiment comprises a substantially portable and self-contained unit
which is provided with a handle 210, a pair of wheels 214 and a pair of
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front support legs 218 to allow the unit to be easily wheeled between
sites.
The front panel 222 of the unit includes all of the necessary
controls, connections and indicators for operating the unit, apart from the
5 power connection lead (not shown) and a 15 amp resettable circuit
breaker (not shown) which are mounted on the rear of the unit.
Specifically, pressure connectors 76, 100 and 108 are located on front
panel 222 as is drain connector 84. Control valves 72, 80, 92 and 104
are also conveniently located on front panel 22.
As will be discussed in further detail below, front panel 222 also
includes several other components. An industry standard connector 226
for a 24 Volt DC tank access fitting and an associated override switch
228 are provided, as are a pair of pressure gauges 230, 234 which
indicate the pressure on the high pressure and low pressure sides of
compressor 28 respectively. Also, an hour-meter 238 is provided as is a
selector switch 242, a power indicator light 246, a system evacuation
indicator light 248 and a recovery indicator light 250. Each of these
components, and their use is discussed in more detail below.
It is contemplated that, in most circumstances, it will be preferred
to filter and/or dry refrigerant, to remove particulates and moisture,
prior to entry of the refrigerant into the recovery and recycling system
20. Accordingly, a disposable filter dryer unit 254 is also provided and
is preferably mounted on unit 200, adjacent front panel 222. In the
preferred embodiment, filter dryer unit will remove particles as small as
25 microns in size. Filter drier unit 254 is connected between product-in
connector 76 and a filter-in connector 260 which allows easy use and
replacement of filter drier unit 254 as required.
~1~7~3~
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The operation of the present invention will now be described with
reference to the above-described preferred embodiment and Figure 4.
As shown in Figure 4, unit 200 is moved to a location allowing
convenient access to the refrigeration equipment 300 to be serviced.
S Valves 72, 80,92 and 104 are closed and a storage tank 304, suitable for
receiving pressurized refrigerant, is connected to connector 108 by a
standard pressure line 306.
In the configuration shown, storage tank 304 is not equipped with
a 24V DC tank access fitting so connector 226 is not connected to tank
304 and override switch 228 is instead activated to permit the unit 200 to
operate. In this configuration, the level of refrigerant in tank 304 may
be determined by a weigh scale 308 or by any other convenient method.
In configurations where tank 304 is provided with a 24V DC tank
access fitting, connector 226 would be connected to the access fitting on
the tank and override switch 228 would be deactivated. As is known to
those of skill in the art, such 24V DC tank access fittings provide a
signal when the tank to which they are attached reaches a level equal to
80% of the tank's capacity. When override switch 228 is deactivated,
connector 226 provides unit 200 with the signal from the tank's access
fitting and this signal is employed to shut-down unit 200 to avoid
exceeding the 80% level. In such a case, as will be described in more
detail below, the filled storage tank 304 may be disconnected and
replaced with a similar empty storage tank as required.
The refrigeration equipment 300 to be serviced is connected by a
standard pressure line 312 to filter dryer unit 254 which is in turn
connected to liquid-in connector 76. Pressure line 312 may be connected
to either the low pressure 316 or high pressure side 320 of refrigeration
g
equipment 300 as required, although the high pressure side is generally
preferred. Unit 200 is then connected to an applol?liate power supply
(not shown), lighting power indicator light 246 and recovery and
recycling operations may commence.
Unless performed when unit 200 was last shut down, the first step
in recovery and recycling is to ensure that any residual gases in unit 200
are evacuated. This is accomplished by opening evacuation control valve
92 and moving selector switch 242 to the Evacuation position.
Moving selector switch 242 to the Evacuation position closes
discharge solenoid valve 96, opens evacuation solenoid valve 88,
illuminates evacuation indicator light 248 and starts compressor 28. Any
residual gases in unit 200 are thus expelled by compressor 28 through
evacuation connector 100 along the path indicated by the arrows in
Figure 5. When unit 200 is substantially evacuated, which the operator
may determine by monitoring the vacuum developed within unit 200 as
shown by pressure gauge 234, evacuation control valve 92 is closed and
selector switch 242 is moved to the off position, turning compressor 28
and evacuation indicator light 248 off.
Next, control valve 72 is opened, allowing refrigerant fluid and/or
vapour to pass through pressure line 312 from equipment 300, through
filter dryer unit 254 into recovery and separation unit 24. Product-out
control valve 104 is opened to allow the refrigerant eventually recovered
and recycled by unit 200 to enter storage tank 304. Selector switch 242
is then moved to the recovery position, opening discharge solenoid valve
96, closing evacuation solenoid 88, illlllmin~ting recovery indicator 250
and starting compressor 28.
~1~71~1
-10-
The recovery and reclamation process proper now commences as
refrigerant vapour or liquid is drawn into recovery and separation unit 24
by compressor 28 which m~int~in~ a vacuum equal to approximately ten
inches of mercury in recovery and separation unit 24. When refrigerant
vapour is drawn from equipment 300, recovery and separation unit 24
acts to separate out any particulate matter or other cont~min~nt~
rem~ining in the refrigerant after passing through filter dryer unit 254.
Specifically, as best seen in Figure 2, portion 49 of product inlet 48 is
spaced from, and is disposed below, product outlet 52. In this manner,
refrigerant vapour which enters recovery and separation unit 24 must
traverse the distance between portion 49 of product inlet 48 and product
outlet 52. This distance allows particulates and other cont~min~nt~ to
separate from the refrigerant vapour and collect at the bottom of
recovery and separation unit 24.
The refrigerant vapour is drawn from recovery and separation unit
24, through product outlet 52, into compressor 28. The refrigerant
vapour is compressed to a hot, high pressure gaseous state by
compressor 28 and is first circulated through heating coil 44 in recovery
and separation unit 24 and then through condenser 32 before finally
entering storage tank 304 through pressure line 306. The path of the
refrigerant vapour through unit 200 is indicated by arrows in Figure 6.
When liquid refrigerant is drawn from equipment 300, the liquid
enters recovery and separation unit 24 where it collects. The heat from
heating coil 44 and the vacuum m~int~ined in recovery and separation
unit 24 by compressor 28 result in the liquid refrigerant boiling to form
refrigerant vapour which is drawn off by compressor 28 as previously
described. Thus, the liquid refrigerant is distilled and any oil or other
)~ tl~
- 1 1 -
cont~min~nts which are less volatile than the refrigerant collect at the
bottom of recovery and separation unit 24.
Level sensor 40 is provided to ensure that recovery and separation
unit 24 does not fill with liquid to the point were the liquid might enter
5 product outlet 52. This prevents liquid refrigerant which has yet to be
distilled and oil or other liquid cont~min~nts which have been separated
from the refrigerant from reaching compressor 28. Specifically, when
the level of liquid in recovery and separation unit 24 reaches a
predetermined level, level sensor 40 produces a signal which shuts
10 product-in control solenoid valve 68 for a predefined time period which,
in the preferred embodiment, is set at 32 seconds.
With product-in control solenoid valve 68 shut, distillation of the
refrigerant in recovery and separation unit 24 proceeds, lowering the
level of refrigerant, until the end of the predefined time period when
15 product-in control solenoid valve 68 is again opened.
While it is not contemplated that large amounts of liquid
cont~min~nts will be collected in a single use, in the event that it is the
level of separated cont~min~nt.c (oil) that activates level sensor 40, level
sensor 40 will immediately close product-in control solenoid valve each
20 time the predefined time period expires. This rapid cycling of product-in
control solenoid valve will be readily apparent to the operator of unit 200
who may then take steps to remove the cont~min~nt.s from recovery and
separation unit 24 as is described below.
As will be apparent to those of skill in the art, heating coil 44
25 makes use of the otherwise wasted heat energy in the refrigerant which
have been compressed by compressor 28 and also reduces the BTUH
capacity required for condenser 32.
-12-
If equipment 300 contains a relatively large amount of refrigerant,
storage tank 304 may be filled prior to complete evacuation of equipment
300. In such a case, filled storage tank 304 may simply be exchanged
for a replacement storage tank by moving selector switch 242 to the off
5 position, closing product-out control valve 104 and detaching the full
storage tank 304 from pressure line 306 and attaching a replacement
empty storage tank 304 to pressure line 306. Product-out control valve
104 is then re-opened and selector switch 242 is moved back to the
recovery position.
Once equipment 300 has been substantially emptied of refrigerant,
as determined by monitoring the pressure on the high pressure side of
compressor 28 with pressure gauge 230, product-in and product-out
control valves 72 and 104 are shut and unit 200 is detached from
equipment 300 and storage tank 304.
The refrigerant rem~ining in unit 200 is evacuated, as was
described above, by moving selector switch 242 to the evacuation
position and opening evacuation control valve 92. In the pl~r~lled
embodiment, the pressure lines used to cormect the various components
of unit 200 is of a small diameter and short lengths and thus, only a
20 minim~l amount of refrigerant remains in unit 200 to be evacuated.
Once evacuated, unit 200 may be brought back to ambient
pressure and the cont~min~nt~ rem~ining in recovery and separation unit
24 may now be removed by opening cont~min~nt-out control valve 80.
As will be understood by those of skill in the art, the frequency with
25 which cont~min~nt~ need be removed from unit 200 will vary depending
upon the particular equipment 300 from which the refrigerant are
recovered and the degree to which the refrigerant had been cont~min~ted.
-13-
It is contemplated that hour-meter 238 will provide a useful indication as
to when such removal need be effected.
It is ~r~relled that unit 200 be evacuated of refrigerant after each
use to allow removal of cont~min~nt~ and to ensure that refrigerant is not
vented to the atmosphere.
The present invention provides an additional function which it is
contemplated will prove to be useful. In the past, refrigeration
equipment was charged with refrigerant by connecting the low pressure
side of the equipment to a supply of virgin refrigerant and allowing the
refrigerant to be vaporized and drawn into the refrigeration equipment by
the equipment's compressor. However, some refrigeration equipment
now in use employs SUVA refrigerants which include a blend of three
different CFC compounds with differing physical characteristics
(including their volatility). Thus, if attempts are made to charge
refrigeration equipment in the conventional manner with SUVA
refrigerants, the most volatile components of the blend charge the system
while the components with a lower degree of volatility remain in the
supply tank. This obviously results in an iml)roper SUVA mixture in the
refrigeration equipment.
With the present invention, the liquid out connecter of a supply of
SUVA refrigerant may be connected to product-in connector 76 and the
high pressure side of the equipment to be charged may be connected to
product-out connector 108. The unit, in accordance with the present
invention, is then operated in the recovery mode, as described above, to
actively 'pump' liquid SUVA refrigerant from a supply tank into the
recovery and separation unit and then to the refrigeration equipment. In
this fashion, the SUVA refrigerant is drawn from the supply in the liquid
-14-
state, ensuring the proper mixture, before being pressurized and supplied
to the refrigeration equipment.
A schematic representation of another recovery and recycling
system in accordance with the present invention is indicated generally at
20' in Figure 7. System 20' includes an oil separator 402, an in-line
filter/dryer 400, an automatic expansion valve 404, a heat exchanger
408, a compressor 28' and a condenser 32'. Oil separator 402 includes
a product inlet 48', a product outlet 52' and a cont~lnin~nt outlet 56'.
Control valves 416, 420 and 424 are all three-position valves
which allow their one inlet to be connected to either of their first and
second outlets or placed in a closed position. Product inlet 48' is
connected between the first outlet of control valve 416 and the second
outlet of valve 424. The inlet of control valve 416 is connected to a
sight glass 412, equipped with a moisture indicator, which is in turn
connected to a four port cross-over valve 428 having first and second
positions. In the first position, ports 1 and 2 are interconnected as are
ports 3 and 4. In the second position, ports 1 and 4 are interconnected
as are ports 2 and 3.
Product outlet 52' is connected via filter/dryer 400, automatic
expansion valve 404 and the low temperature side of heat exchanger 408,
to the low pressure side of compressor 28'. The high pressure side of
compressor 28' is connected to the high temperature inlet of heat
exchanger 408. The high temperature outlet of heat exchanger 408 is
connected to inlet 60' of heating coil 44'. Outlet 64' of he~ting coil 44'
is connected to the inlet of control valve 420.
First outlet 420a of control valve 420 is connected to the inlet of
condenser 32'. The outlet of condenser 32' is connected to the inlet of
-1S- 2~ 113~
valve 424. Second outlet 420b of valve 420 is cormected to second
outlet 416b of valve 416, first outlet 424a of valve 424 and to port 4 of
cross-over valve 428.
Port 3 of cross-over valve 428 is cormected to product outlet 108',
and port 1 of cross-over valve 428 is cormected to product inlet 76' via a
safety solenoid valve 432. Both inlet 76' and outlet 108' are provided
with suitable pressure connectors, such as 1/4" female cormectors.
Similarly, cont~min~nt outlet 56' and compressor oil drain 111 '
are provided with suitable drainage connectors 84' and 436 respectively.
Safety solenoid valve 432 is normally closed when the power to
system 20' is off. Solenoid valve 432 prevents refrigerant from passing
through system 20' and being accidentally released to the atmosphere.
This situation could otherwise occur if control valves 416, 420, and 424
are left in an open position when cormecting the system 20' to a system
requiring repair.
In the preferred embodiment, oil separator 402 is m~mlf~ctured by
Parker as their model "Oil Separator, Size B". Heating coil 44'
comprises a plurality of coils of pressure line which wrap the lower
portion of the exterior surface of tank 24'.
Filter/dryer 400 is placed downstream of oil separator 402 to
remove particles and moisture from the refrigerant prior to the
refrigerant entering compressor 28'. Preferably, filter/dryer unit 400 is
dlsposable and is selected to remove particles as small as 25 microns in
slze.
Automatic expansion valve 404, is an ALCO model ACP9, and
senses the pressure of refrigerant at the valve outlet and adjusts the size
of its orifice to m~in~in a constant pressure to compressor 28'.
-16-
Automatic expansion valve 404 is provided with an adjustable outlet
pressure control, which in the presently preferred embodiment, is set to
approximately 45 psi.
Heat exchanger 408 may be any suitable heat exchanger for
refrigerant as would be apparent to those of skill in the art. In the
preferred embodiment, heat exchanger 408 is a Doucette Industries
model SLHEl/3 which is a finned tube-in-tube type heat exchanger rated
at 4000 BTUH.
Compressor 28' may be any compressor suitable for compressing
refrigerant as will be understood by those of skill in the art. In the
pl~fell~d embodiment, compressor 28' is a 0.32 CFM, 1/6 HP
compressor m~nllf~ctured by Embraco, model # EM 55 NR.
Compressor 28' is capable of producing a vacuum of 20" of mercury in
system 20' and operates at a normal capacity of up to 4.5 lbs per minute
of liquid or up to .55 lbs per minute of vapour refrigerant.
Condenser 32' may be any suitable condenser designed for
refrigerant purposes. In the pl~r~ d embodiment, condenser 32' is an
air cooled 2560 BTUH (at 20TD) capacity condenser m~mlf~ctured by
Astro Air, model #30226. An electrically driven cooling fan (not
shown) may be optionally provided for use with condenser 32', as would
be apparent to one of skill in the art.
As shown in Figure 8, system 20' comprises a substantially
portable, self contained unit which is provided with a handle 210'. The
handle 210' allows system 20' to be carried between work sites.
A front panel 222' includes all of the necessary controls, and
indicators for operating system 20'. A power connection lead (not
shown) is located at the rear of the unit. Pressure and drain connectors
2 ~ 2 ~
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76', 108', 84', and 436 are located on a side panel 456. Control valves
416, 420, and 424 and sight glass 412 are located on front panel 222'.
As will be discussed in ffirther detail below, front panel 222' also
includes several other components. An industry standard 24 Volt DC
5 tank-access connector 226' is provided. Also, a low-pressure-side gauge
234' is provided which indicates pressure on the low pressure side of
compressor 28'. A power switch with integral indicator light 246' is
also included.
As seen in Figure 9, rear panel 448 includes a removable portion
452 which provides access to filter/dryer unit 400. Storage for the
power cord, a 24 Volt DC tank-full connection cord and operating hoses
is also provided behind panel 452.
The operating modes of this embodiment will now be described
with reference to Figures 10 through 15. The presently preferred
embodiment provides four modes of operation, including a self-
evacuation mode.
The first mode of operation allows an operator to drain an amount
of liquid refrigerant from a system 300' under repair by employing the
pressure differential between the refrigerant in system 300' and the
industry standard storage tank 304'. This mode of operation is useful
when system 300' requires evacuation prior to servicing but the
refrigerant either does not require recycling or will be recycled at a later
time.
As shown in Figure 10, a conventional refrigerant service
manifold 436 is connected between the high and low pressure outlets 440
and 444 respectively. The outlet of manifold 436 is connected to the
product inlet 76' on system 20'. Product outlet 108' is connected to a
-18-
liquid valve 412 located on storage tank 304'. The 24 Volts DC tank-
access fitting 226' must be connected to storage tank 304' via a suitable
connector, or system 20' will not operate. Once the above described
connections have been established, service manifold 436 is set with the
low pressure valve closed and the high pressure valve open.
Figure 11 illustrates the internal operation of the first mode of
operation. With the power to system 20' turned on, solenoid valve 432
opens, allowing refrigerant from system 300' to enter system 20'.
Control valve 416 is moved to its second position to connect its inlet to
outlet port 416b. Cross over valve 428 is set to the first position and,
due to the above-mentioned pressure differential, liquid refrigerant flows
from manifold 436 outlet into product inlet 76', through control solenoid
432, and cross-over valve 428, to sight glass 412. From sight glass 412
the liquid refrigerant passes through control valve 416, back through
cross-over valve 428 and is routed through product outlet 108' into
storage tank 304'.
Sight glass 412 is used to determine when no liquid refrigerant is
present, or when the refrigerant flow has stopped thus indicating that the
pressure between the system 300' and the storage tank 304' has
equalized. At this point, the rem~ining refrigerant in the system 300' is
extracted using the second mode of operation.
The second mode of operation is achieved by turning control
valves 416, 420 and 424 to their respective first outlet positions 416a,
420a, and 424a, as indicated in Figure 12. Both high and low pressure
valves on service manifold 436 are opened and the power to system 20'
is turned on, activating compressor 28'. Solenoid valve 432 opens
allowing refrigerant liquid, vapour and any entrained cont~min~nt~ into
~271~4
-19-
system 20'. Refrigerant and cont~min~nt~ are drawn through cross-over
valve 428, sight glass 412, control valve 416 and into oil separator 402.
Liquid refrigerant and cont~min~nts settle to the bottom of oil separator
402 while refrigerant vapour exits via outlet 52'. The vapour then flows
5 through heating coil 44', where heat is transferred to the liquid
refrigerant and cont~min~nt~ in oil separator 402. Liquid refrigerant in
separation unit 24' is vaporized by heat supplied from heating coil 44'
further reducing the heat of the vapour in heating coil 44'. As
separation unit 24' is of a physical size which improves the portability of
system 20', there may be situations in which oil separator 402 becomes
"flooded" with the liquid refrigerant/cont~min~nt mixture. In this case,
the liquid mixture may leave outlet 52' without being distilled. If such a
condition occurs, filter/dryer 400 is provided to absorb and/or clean
cont~min~nt~ from the refrigerant and automatic expansion valve 404 is
provided to ensure that liquid refrigerant is throttled to a saturated
vapour state before entering the heat exchanger 408.
The vapour refrigerant continues to be drawn by compressor 28',
through filter/dryer 400 where the vapour receives a final treatment to
remove any significant rem~ining moisture and/or particles. From the
filter/dryer 400, the vapour enters automatic expansion valve 404. As
previously described, automatic expansion valve 404 m~int~in~ the
refrigerant vapour at a constant pressure of approximately 45 psi at the
valve outlet. Valve 404 ensures that the refrigerant is "throttled" to a
saturated vapour state.
The saturated vapour then passes through the low temperature side
of heat exchanger 408 and into compressor 28'. As will be apparent to
those of skill in the art, compressor 28' compresses the refrigerant
~1~ 71 ~
-20-
vapour into the superheated region. The superheated vapour then passes
through the high temperature side of heat exchanger 408, where some of
its heat is transferred to the incoming vapour in the low temperature side
of heat exchanger 408, and through heating coil 44'.
Exiting heating coil 44', the refrigerant vapour, which is no
longer in a superheated state, travels through control valve 420 to
condenser 32'. Condenser 32' cools the refrigerant to a liquid state after
which the refrigerant flows through control valve 424 and is routed
through cross-over valve 428. The recycled refrigerant liquid then
passes through product outlet 108' and into storage tank 304'.
This process continues until compressor 28' has produced a
vacuum of 20 inches of mercury at which point a low pressure sensor
(not shown) turns off compressor 28' and the air fan for condenser 32'
(if present). In the pler~lled embodiment, the pressure sensor is a model
#20PS042DCV03CV20C m~mlf~ctured by Texas Instruments. At this
point, substantially all of the refrigerant and cont~min~nt~ would have
been removed from the system 300'.
As would be apparent to one of skill in the art, it is possible to
omit the first mode of operation and to operate system 20' entirely in the
second mode of operation to recover and recycle refrigerant. As
previously mentioned, the first mode of operation is suitable to
substantially evacuate a unit under repair when recycling is not required.
The third mode of operation is illustrated in Figures 13 and 14
and is referred to as "push-pull" mode. In this case, high pressure
refrigerant vapour from storage tank 304' is pressurized and used to push
liquid refrigerant from system 300' into storage tank 304'.
~1~ 71~ 1
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To achieve the third mode, a refrigerant line is connected between
the liquid valve on storage tank 304' and the high pressure side of
system 300'. The other above-described connections remain in place.
As shown in Figure 14, cross-over valve 428 is turned to the
second position which effectively reverses the function of product inlet
76' and product outlet 108' connections. Control valve 416 is turned to
first position 416a and control valve 420 is moved to second position
420b, control valve 424 is moved to the closed position. Refrigerant
vapour from storage tank 304' is drawn into product outlet 108' and is
diverted through the cross-over valve 428, sight glass 412 and control
valve 416, into oil separator 402. From separation unit 24', the vapour
passes through filter/dryer 400 and automatic expansion valve 404 to
compressor 28' where it is pressurized. The pressurized refrigerant
vapour then travels through heating coil 44' and is routed through control
valve 420, cross-over valve 428, and out through the product inlet 76'.
The pressurized vapour then enters low pressure side 444 of
system 300'. Any liquid refrigerant rem~ining in system 300' is pushed
out of high pressure outlet 440 through the liquid valve and into storage
tank 304'.
If during operation in any of the three modes, storage tank 304'
reaches a level of 80% full, the tank access fitting is triggered and
system 20' will shut down until the operator replaces storage tank 304'.
When operating in either the second or third mode, low pressure
gauge 234' indicates when system 300' has been substantially evacuated.
As previously mentioned, system 20' will continue to remove refrigerant
from system 300' until compressor 28' develops a vacuum of
approximately 20" mercury. At this point system 20' automatically shuts
-22-
off. A waiting period of approximately S mimltes is suggested to allow
any refrigerant rem~ining in the separating unit 24' with the captured
cont~min~ntc, to vaporize. If enough refrigerant vaporizes from the
captured cont~min~nt~ such that the pressure in system 20' rises above a
vacuum of approximately 20 " mercury, compressor 28' will re-start
until the predefined vacuum is again developed.
Once system 300' is subst~nti~lly evacuated, system 20' is placed
in the fourth self-evacuation mode. As Figure 15 shows, in this mode
control valve 416 is moved to the closed position and control valves 420
and 108' are both set to their respective second positions while cross-
over valve 428 is placed in its first position. With the power turned on,
compressor 28' evacuates any residual refrigerant from the high pressure
side of condenser 32' through all of the in-line components. Evacuated
refrigerant is routed through control valve 420 and out to storage tank
304' via product outlet 108'. Again, once a vacuum of 20" mercury is
developed in the system 20', compressor 28' will automatically shut off.
When the self evacuation is complete, system 20' is turned off and
captured oil and cont~min~nt~ can be drained from oil separator 402, via
drain 108', into a suitable container for disposal.
It will be apparent from the discussion above that the present
invention provides a novel system and method for the recovery and
recycling of refrigerants, such as environmentally (l~m~ging CFC
compounds. It will also be apparent that, while a particular p~ d
embodiment of the present invention is described herein, variations and
modifications will occur to those of skill in the art and should not be
considered as departing from the spirit of the invention.
