Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
Refrigerant Reclaim Unit
FIELD OF THE INVENTION
This invention relates to a method and apparatus
for the reclaiming of gases and refers particularly, though
not exclusively, to a method and apparatus for the
recovery, cleaning and recycling of air-conditioning and
refrigeration gases, commonly known as Chlorina~ed Fluoro
Carbons (C.F.C.).
DISCUSSION OF PRIOR ART
For many years, it was the practice when dealing
with air-conditioning units with gas as the refrigerant to
allow the gas to escape into the atmosphere when repairing
the system, or re-gassing the system. Over the last few
years, it has been realised that this releasing of the
refrigerant gases into the atmosphere has been the cause of
much pollution and, specifically, a contributor to the
reduction of the ozone layer around the earth. It is
therefore now a requirement in some countries and highly
recommended in others that such gases be reclaimed and,
where possible, cleaned and recycled for future use. Where
this is not possible, they should be recovered and
destroyed in a way so as to not increase pollution nor
reduce the ozone layer.
A number of proposals have been made for such
recovery, cleaning and recycling systems. Most of these
are very large and complex pieces of equipment that are
beyond the financial reach of most of those who deal in
air-conditioning units. Furthermore, their almost inherent
lack of portability means they are not very suitable for
on-site work. As this is a significant percentage of the
work, the development of a unit that is portable to enable
on-site work to be done has been the subject of a great
deal of research.
It is therefore the principal object of the present
invention to provide a recovery, cleaning and recycling
system and apparatus for gases, particularly refrigerant
gases, and which is able to be relatively easily moved.
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SUMMARY OF THE INVENTION ~04
According to the present invention there is
provided apparatus for the recovery, cleaning and recycling
of gases comprising a portable frame containing means to
collect the gas, preferably refrigerant gas from
refrigeration equipment, first filter means to scrub the
gas to remove large contaminants, second filter means to
dry and further filter the gas, a compressor to compress
the filtered gas, an oil separator to remove oil that may
have contaminated the gas whilst in the compressor, said
separator returning the collected oil bac]c to the
compressor, a condenser to cool the gas and collection
means to collect the gas in liquid form whereby the gas can
be recovered, cleaned and charged for recycling in a single
pass.
According to the present invention there is
provided a method of recovering, cleaning and recycling a
gas preferably refrigerant gas including the steps of
passing the gas through a scrubber to remove large
: contaminants, passing the gas through a dryer to filter and
dry the gas, passing the gas through a compressor, passing
the gas through an oil separator to prevent discharge of
oil from the compressor, passing the gas through a
condenser to cool the gas and passing the gas to collection
means in liquia form whereby in a single pass the gas is
recovered cleaned and charged ready for recycling.
DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be
.~ described by way of example only with reference to the
accompanying drawings in which:
Figure 1 is a schematic layout of one form of
refrigerant reclaim unit,
Figure 2 is a perspective view of the unit when
: mounted on a small trolley,
: Figures 3 and 3A are schematic system layouts of an
~ alternative form of reclaim unit.
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DESCRIPTION OF THE PREFERRED EMBODI~ENTS Z~4525
The reclaim unit described hereunder provides
C.F.C. gas recovery, cleaning and recycling in a single
unit that can be mounted on a portable trolley. One
embodiment of the invention is illustrated with reference
to Figures 1 and 2. The C.F.C. gas that is the subject to
the invention is a refrigerant such as, for example, a
refrigerant used in domestic or commercial appliances of
the nature of refrigerators and freezers, air-conditioning
units including automotive air-conditioning units. The
invention does however embrace any other gas where
recycling is a possibility.
As shown in the schematic layout of Figure 1 r the
gas is passed into the unit via a suction pick-up hose T.
A discharge pic~-up hose U is also provided. A set of
pressures gauges A enables an operator to keep a careful
watch upon the pressure to ensure proper and adequate
operation so that the equipment cannot be damaged by over
pressure or under pressure operations.
The gas is first passed via a 1/4 inch diameter
pipe A2 through a pressure regulating valve B to ensure
that the gas passes through the system at as high a
pressure as possible without damaging or overloading a
downline compressor. The outlet B2 from the valve B passes
to a scrubber C via a 3/8 inch diameter pipe. The scrubber
is designed to filter and remove large contaminants such as
metal pieces, dirt and the like.
The scrubber is designed with a diameter large
enough to significantly reduce the velocity of the gas from
the 3/8 inch entry pipe to cause the contaminants to settle
out to the bottom where they can be easily removed. The
scrubber is therefore also designed to work in tandem with
a dryer D as a pre-filter of contaminants and heavy oils
and thereby increase the efficiency and life of the filter
medium in the dryer. A scrubber drain valve K is provided
together with a scrubber oil outlet P so as to be able to
remove these contaminants after each operation. The
scrubber C is in the form of a 3 inch diameter, 6 inch long
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copper hollow cylinder mounted with its axis vertical and
closed at either end with end caps C2~ C3. The scrubber
cylinder C is filled with stainless steel scrubber pads
(not shown). The gas enters the scrubber C from the top
via a pipe C4 that extends to the base of the copper
cylinder. At this stage, the velocity of the yas is
substantially reduced thereby allowing the contaminants to
collect in the base for removal via a 1/4 inch diameter
draining pipe C5 that extends from the base of the cylinder
through the top end cap C2 to the drain valve X.
The outlet C6 from the scrubber C passes the ~as to
the drier D via a 3/8 inch diameter pipe. The drier D is
fitted with a permanent and heavy duty burn-out core, to
further filter out smaller particles of contamination, acid
and moisture from the gas. The core is a hollow open ended
cylinder of activated carbon manufactured by Alco -
Controls Division of Emerson Electric Company under the
brand W48 - Activated Carbon Style Filter Drier Block.
The outlet D2 from the drier D passes into the
compressor E via pipework that is initially 3/8 inch
diameter but steps down to 1/4 inch diameter on entry to
the compressor E.
; It is to be noted that the gas is first scrubbed
and dried and all acid removed before it enters the
compressor. As the gas is cleaned and filtered before
entering the compressor the dome of the compressor is
protected resulting in a much longer compressor operating
life. The compressor serves the role of pumping the gas
through the circuit as well as increasing the temperature
and pressure of the gas. A compressor oil drain valve L
and oil outlet Q are provided off the base of the
compressor via a 1/4 inch diameter pipe E4. The compressor
oil drain valve L is used to drain excess oil from the
compressor to the oil outlet Q.
The outlet E2 from the compressor E goes onto an
oil separator F via a 1/4 inch diameter pipe. The
separator F collects oil and ensures that a minimum of oil
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contamination passes with the reclaimed refrigerant into
the gas storage cylinder. This collected oil is then
passed back to the compressor sump via a 1/4 diameter
return pipe E3 to maintain proper oil level.
The outlet F2 from the separator F is into a
condenser G via a 1/2 inch diameter pipe. The condenser G
is preferably a modine condenser to provide adequate
condensing capacity for R-12, R-22 and R-502 refrigerants
at high ambient temperatures. The condenser liquifies the
high pressure gas by extracting heat through use of an air
current from an electrically driven fan.
From the outlet G2 of the condenser G, the liquid
gas passes through a check valve H which is mounted in the
1/4 inch diameter delivery line H2 to ensure that the gas
that has been cleaned cannot be returned back into the
system when the system is in the "Off" cycle. A pressure
gauge J coupled via a 0.050 inch capillary line J2 is
provided so that the outlet pressure can be carefully
monitored by an operator. A delivery valve M is provided
to enable the liquid gas to be supplied through delivery
outlet R for collection in a suitable cylinder. A crystal
salts sight glass N is fitted to the 1/4 inch diameter
outlet line H3 to show the condition of the gas as this
would indicate when it would be necessary to change the
dryer core to ensure adequate and proper operation. The
sight glass that has been selected is of high quality due
to the type of indicator, e.g. Salt Crystals. These
crystals indicate the moisture content in the refrigerant
by changing colour when an unacceptable level has been
reached in excess of 15 ppm. Unlike litmus type indicators
this sight glass can withstand in excess of 1,000 accurate
colour changes without breaking down. As a "1 pass" unit
of this nature relies on this glass to indicate when the
drier core needs replacing it is essential to use a Salt
Crystal type sight glass, manufactured to the required
;~ specification, to indicate change at a 15 ppm moisture
level.
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For the unit as described above, there is
preferably included a high pressure/low pressure switch S
coupled to the outlet line G2 via 0.050 inch diameter
capillary line S2 so as to protect the system against
misuse, e.q. starting the unit with the cylinder valve
closed.
As can be readily understood, this apparatus and/or
method not only recovers or evacuates the gas, it also
cleans it and recycles it for reuse. This not only
protects the environment by decreasing the requirement for
new gas, but prevents the significant re-purchasing costs
of gas. The expression 'cleaning' embraces cleaning as
dictated by U.S. Standards. The clean gas has less than 15
parts per million moisture and less than 0.05% by volume
acid and oil.
~ t has been made possible to make a unit in
accordance with the above description of a size to be able
to fit onto a txolley such that it is transportable and
able to be used on-site. An illustration of such a unit is
shown in Figure 2 in which the pipework and exterior panels
are removed for clarity. The sight glass N and delivery
outlet M are positioned on the front panel of the unit.
The unit is arranged to be coupled to a suitable source of
mains voltage to power the componentry. Such a unit may
have a nominal capacity of the order of up to 20 ~ilograms
of gas per hour, depending on the pressure of the gas
entering the unit and the ambient temperature. The unit
provides the major advantage that it can as a small
portable unit clean for recycling gas in a single pass.
In a smaller domestic reclaim unit shown in Figures
3 and 3A, the scrubber C of the first embodiment is removed
as in the oil separator F between the compressor E and the
condenser G. The remaining circuitry is much the same with
the gas being passed through an oil separator F2 via an
inlet port B and inlet valve V. The separated oil is
tapped from the separator F2 via line F3 and outlet F4.
From the oil separator the gas flows to the dryer D and
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then into the compressor E and onto the modine condenser G
via check valve H. The remaining circuitry is
substantially as the first embodiment.
This unit is handheld weighing 15 kg and has a
capacity of cleaning 7 kg of gas per hour in contrast to
the large unit of Figures 1 and 2. The unit of Figure 3 is
particularly useful for the reclaiming, cleaning and
recycling in a single gas of C.F.C.~s in units such as
domestic fridges and freezers and small domestic
air-conditioning units.
Throughout the reclaim unit special care has been
taken with regards to pipework, sizing and assembly. If
pipework is undersized the unit will not perform at the
best possible efficiency and therefore the amount of gas
processed per hour would be reduced. On the other hand, if
the pipework was grossly oversized in parts of the circuit,
such as in the scrubber, solid contaminants and heavy oils
will separate out of the refrigerant and settle in these
low velocity areas. This condition can eventually cause
blockages and unnecessary failure.
Particularly, the relationship between components
presented by the pipework is equally important in that
components will not work in tandem and achieve peak
effi~iency if the pipework is such that there is an
efficient balance between those components. As this unit
is being used to recover and reclaim refrigerant which is
frequently contaminated with solids or heavy oils it is
even more critical that care be taken and that proper
pipework sizing and balance and installation be closely
adhered to.
Whilst there has been described in the foregoing
description a preferred construction of a gas recovery,
cleaning and recycling unit as well as a method of
recovering, cleaning and recycling a gas it would be
understood by those skilled in the art that many variations
or modifications in details of design or construction may
be made without departing from the essential nature of the
present invention.
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