This invention relates generally to removal of impurities or contaminants from refrigerants used in refrigeration systems, and in particular to apparatus for separating and removing those impurities or contaminants from the refrigerant of such systems. The invention is applicable to vapour compression refrigeration systems used in air conditioning plants and equipment, and it will be convenient to hereinafter describe the invention in relation to that exemplary application. It is to be appreciated, however, that the invention is not limited to that application.

After an extended period of use, refrigerant used in a vapour compression refrigeration system tends to become contaminated with foreign impurities. This may include liquid matter such as oil as well as solid impurities including waxes and metal particles. The impurities reduce the efficiency of operation and retard the cooling ability of the refrigeration system. Therefore, after contamination reaches unacceptable levels, the refrigerant needs to be replaced. At present the contaminated refrigerant is usually released into the atmosphere and replaced with fresh refrigerant. As some of the most commonly used refrigerants are fluorocarbons such as

R-ll (CC1-F) , and because of the adverse effects that fluorocarbons are known to have one the ozone layer of the upper atmosphere, this should no longer be considered an acceptable option.

It is therefore preferably that the refrigerant be recycled by removing the impurities and re-using the cleaned or de-contaminated refrigerant. Driers are available for removing liquid impurities from refrigerants. However, these

driers are not able to effectively remove solid impurities from the contaminated refrigerants.

Therefore, it is an object of the present invention to provide an apparatus for separating contaminants, particularly solid impurities, from the refrigerant.

With that in mind, the present invention provides apparatus for separating and removing contaminants from refrigerant of a vapour compression refrigeration system, including: a primary separation chamber; a refrigerant inlet through which contaminated refrigerant is introduced into the primary separation chamber; a refrigerant outlet through which de-contaminated refrigerant is removed from the apparatus; a contaminant outlet through which contaminants separated from the refrigerant are discharged from the apparatus; and, heating means for heating to vapourize the contaminated refrigerant, wherein vapourized refrigerant in the primary separation chamber separates from solid contaminants and liquid contaminants having a boiling point higher than the refrigerant, the de-contaminated refrigerant being removed through the refrigerant outlet while the separated contaminates accumulate within the apparatus for subsequent discharge through the contaminant outlet.

In at least one embodiment, the apparatus further includes a secondary separation chamber and communication means permitting fluid communication between the primary and secondary separation chambers. In this embodiment, the refrigerant outlet is connected to the secondary separation chamber so that in use, vapourized de-contaminated refrigerant in the primary separation chamber flows to the secondary separation chamber and from there flows through the

refrigerant outlet out of the apparatus, with contaminants entrained in the vapourized refrigerant in the secondary separation chamber tend to separating out from the refrigerant in the secondary separation chamber. in at least one embodiment of the apparatus, a primary separation vessel providing the primary separation chamber and a secondary separation vessel provides the secondary separation chamber. Moreover, at least one connection tube extends between the separation vessels providing the co munication means in this at least one embodiment.

In at least one embodiment, the heating means includes one or more heating elements located in the primary separation chamber for vaporizing contaminated refrigerant entering through the refrigerant inlet. The heating element(s) may include a heating tube extending within the primary separation chamber and through which a heated fluid is passed to transfer heat energy to refrigerant within the primary separation chamber.

In at least one embodiment, the apparatus further includes control means for controlling flow of refrigerant through the refrigerant inlet and outlet and flow of contaminants through the contaminant outlet, wherein during an operating cycle of the apparatus, the control means initially opens the refrigerant inlet and refrigerant outlet to introduce contaminated refrigerant into the primary separation chamber and simultaneously remove from the apparatus de-contaminated refrigerant. Thereafter the refrigerant inlet and refrigerant outlet are closed, and the contaminant outlet is opened for discharge of accumulated contaminants from the apparatus. The control means then operated to close the

contaminant outlet.

The control means may include control valves actuable to open and close the refrigerant inlet and refrigerant outlet and contaminant outlet. Moreover, at least one timer device may be provided and operable to cause timed actuation of the control valve(s) to open and/or close the inlet and outle (s) . The control means may further include at least one pressure sensitive switch. That switch is operable to cause actuation of the control valve to open the contaminant outlet when refrigerant vapour pressure within the primary separation chamber reaches a predetermined upper level and thereby discharge the accumulated contaminants through the contaminant outlet, and to subsequently close the contaminant cutlet when that refrigerant vapour pressure drops to a predetermined lower level.

The following description refers to a preferred embodiment of the apparatus of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the apparatus is illustrated in that preferred embodiment. It is to be understood that the apparatus is not limited to the preferred embodiment as hereinafter described and as illustrated in the drawings. In the drawings: Fig. 1 is a schematic side view of an apparatus according to a preferred embodiment of the present invention; and

Fig. 2 is a schematic diagram of the control means of the apparatus of Fig. 1. Referring initially to Fig. 1 there is generally shown

apparatus 1 having primary separation vessel 2 providing primary separation chamber 3 as well as secondary separation vessel 4 providing secondary separation chamber 5. In this embodiment, separation vessel 4 is located above separation vessel 2 for use of apparatus 1. This assists in minimizing transfer of contaminants from separation chamber 3 as will become more apparent hereinafter.

In this embodiment distinct primary and secondary separation vessels 2,4 individually provide separation chambers 3,5. It is also envisaged that, in at least one alternative embodiment (not shown) , primary and secondary separation chambers 3,4 be enclosed in a single separation vessel with a partition separating those two chambers 3,4.

Separation vessels 2,4 are of any suitable shape and size. In this embodiment, vessels 2,4, each have an elongate tubular body 6 with closed ends 7 to provide cylindrical shaped separation chambers 3,5. Vessels 2,4 are conveniently constructed from materials used in the refrigeration industry, such as 16 gauge refrigeration copper pipe. Refrigerant inlet 8 communicates with separation chamber

3 by introducing contaminated refrigerant into chamber 3, whilst refrigerant outlet 9 communicates with separation chamber 5 for removing de-contaminated refrigerant from chamber 5. In addition, contaminant outlet 10 also communicates with separation chamber 3, adjacent the bottom of chamber 3 as shown, for discharging contaminants from separation chamber 3. In this embodiment, inlet 8 and outlets 9,10 to separation chambers 3,5 are provided by refrigeration standard pipe fittings mounted on vessels 2,4. Apparatus 1 further has communication means 11

permitting fluid communication between separation chambers 3,4. In this embodiment involving distinct vessels 2,4, communication means 9 includes at least one (two as shown) connection tube 12 providing a communication passage between chambers 3,5. A criteria on the selection of the number and size of tubes 12 is that they have a combined communication passage sufficient in size to allow the vaporized refrigerant to pass through into secondary separation chamber 5 at a relatively low vapour velocity. As will become more apparent hereinafter this will minimise the amount of contaminants that may be entrained by the refrigerant. If the vapour volocity is too high then excessive amounts of contaminants may be carried through connection tube(s) 12 between separation chambers 3,5. Apparatus 1 also includes heating means 13 for heating refrigerant to cause vapourization of refrigerant in separation chamber 3. In this embodiment, heating means 13 is supported within chamber 3. However, it is envisaged that, in at least one alternative embodiment (not shown) , heating means 13 is situated outside separation vessel 2 to heat tubular body 6 and thereby refrigerant within separartion chamber 3. In a further embodiment (not shown) , heating means 13 is again situated outside separation vessel 2 and arranged to heat refrigerant before it is introduced into separation chamber 3. One form of heating means 13 for refrigerants such as

R-11 includes heating element 14 passing through separation chamber 3, heating element 14 having heating tube 15 coiled within separation chamber 3 and through a heating fluid such as water flows to transfer heat energy to the refrigerant. Tube 15 is made of copper material formed into a compressed

coil, in at least one embodiment. Since the boiling temperature of R-11 is about 23 C the heat provided by hot water is normally sufficient to vaporize the contaminated refrigerant. Alternative embodiments envisage other heating means 13, such as one or more electrically powered heating elements, the selection of which may depend upon the refrigerant being de-contaminated.

In this embodiment of apparatus 1, heating tube 15 is supported in primary separation chamber 3, with opposing ends of tube 15 being connected to, or forming, heating fluid inlet 16 and outlet 17. In this apparatus embodiment of primary separation vessel 2 having elongated tubular body 6, the external diameter of coiled heating tube 15 approximately corresponds with the internal diameter of tubular body 6. That coiled heating tube 15 extends substantially along the entire length of primary separation chamber 3, in this embodiment, thereby maximizing efficiency of heat energy transfer from the heating fluid to the refrigerant.

In this embodiment, operation of apparatus 1 is controlled by control means 18 as shown in Fig. 2. Control means 18 is electrically powered and enables apparatus 1 to operate on ah automatic basis, in this embodiment. Conveniently, control means 18 is connectable to a mains A.C. electric power supply. Control means 18 includes electrical network 19 incorporating separate control valves 20,21,22 respectively at refrigerant inlet 8 and outlet 9, and at contaminant outlet 10. Those valves 20,21,22 are actuable to open and close inlet 8 and outlets 9,10 thereby to control the flow of refrigerant and contaminants through apparatus 1.

Electromagnetic or solenoid actuated control valves 20,21,22 are used in this embodiment, although alternative control valves may be equally suitable.

Control means 18 also includes timer device 23 operable to cause timed actuation of control valves 20,21 for opening inlet 8 and outlet 9 for predetermined period. Device 23 includes timer 24 and associated switch 25 which is closed for the predetermined period to connect valves 20,21 to the power supply for actuation to open inlet 8 and outlet 9. Timer 24 is conveniently adjustable to vary the predetermined period. That adjustment may be manual.

Control means 18 further includes pressure sensitive switch device 26 operable to cause actuation of control valve 22 for opening outlet 10 when pressure of refrigerant vapour in separation chambers 3,4 reaches a predetermined upper level. In particular, at that predetermined upper level, valve 22 is connected to the power supply for actuation thereof to open outlet 10. Subsequently, as refrigerant vapour pressure drops to a predetermined lower level, pressure switch device 26 operates to disconnect the power supply and valve 22 thereby resulting in the closing of outlet 10.

Pressure sensitive switch device 26 is also interposed in network 19 between the power supply and switch 24, and operable to supply power to timer deivce 23 only when pressure within separation chambers 3,5 is below the predetermined upper level. In this way, pressure sensitive switch device 26 alternatively connects the power supply to control valve 22 and timer device 23. (and thus control valves 20,21). Conveniently, switch device 26 is exposed to refrigerant vapour pressure in secondary separation chamber 5. Switch

device 26 may be adjustable to vary the predetermined upper and lower levels at which switching occurs that adjustment may be manual.

As a fail safe measure, float switch 27 may be provided in a waste container (not shown) receiving the discharged contaminants from outlet 10, to prevent the operation of apparatus 1 should the level of contaminants within the container reach a predetermined maximum level. Float switch 27 operates to disconnect the supply power from network 19 and thereby disable apparatus 1.

In this embodiment, control means 18 also includes check valve 28 provided downstream of contaminant outlet control valve 22 to prevent the contaminants from returning through contaminant outlet 10 into chambers 3,5. In use, apparatus 1 can be installed as a permanent part of a refrigeration system. Thus, apparatus 1 will operate to periodically or continuously de-contaminate the refrigerant of that system. Alternatively, apparatus 1 may be portable for use in de-contaminating refrigerant from a plurality of refrigeration systems, apparatus 1 being transported to those systems as required. In a further arrangement, apparatus 1 may be permanently located at a de-contamination plant remote from refrigeration systems, and the refrigerant from those systems transported in containers to the apparatus for de-contamination and subsequent return to the refrigeration systems.

During a normal operating cycle of apparatus 1 according to this preferred embodiment, refrigerant inlet and outlet control valves 20,21 are initially actuated to respectively allow contaminated liquid refrigerant to be introduced through

open inlet 8 into primary separation chamber 3 and allow de-contaminated refrigerant to be removed from secondary separation chamber 5 through open outlet 9. Contaminant outlet control valve 21 is initially actuated to close outlet 10 during this cycle period. During this cycle period vaporized refrigerant in separation chamber 3 separates from contaminants and flows into separation chamber 5 and finally through outlet 9 to leave apparatus 1. Contaminants, separated from the refrigerant settle and accumulate at the bottom of separation chamber 3. Secondary separation chamber 5 allows any remaining contaminates that may be entrained in the refrigerant to separate out as well as allowing the refrigerant to partially cool before being removed from apparatus 1. Those separated contaminants may drain back to primary separation chamber 3 through connection tubes 12. The refrigerant vapour velocity along connection tubes 12 is such that contaminants in primary separation chamber 3 are not generally entrained into the refrigerant vapour and carried up to secondary separation chamber 5.. After a predetermined period (as set by timer 24), timer device 23 initiates actuation of refrigeration control valves 20,21 to close inlet 8 and outlet 9. In one embodiment the predetermined period is of the order of about 30 minutes.

Closure of inlet 8 and outlet 9 causes the refrigerant vapour pressure to rise within separation chambers 3,5. When that pressure reaches a predetermined upper level (as set by switch device 26), then switch device 26 operates to initiate actuation of contaminant control valve 22 to open outlet 10. In one embodiment, the predetermined upper level of vapour pressure is of the order of 21 Kpa. The refrigerant vapour

pressure which has built up within separation chamber 3, causes contaminants accumulated within chamber 3 to disgorge out through contaminant outlet 10 to a waste container.

Thereafter, the refrigerant vapour pressure within chambers 3,5 drops to the predetermined lower level (as set by switch device 26), whereupon switch device 26 again operates to actuate contaminant outlet control valve 22 to close outlet 10. That operation also reconnects the supply power to timer device 23 which again initiates actuation of valves 20,21 to open inlet 8 and outlet 9 for the predetermined period. The operation cycle thus re-commences.

The apparatus of the present invention enables relatively simple and inexpensive re-cycling of refrigerant from refrigeration systems. As such, costs of operating those sytems may be minimized.

In addition, the ability to re-use the refrigerant means that it does not have to be discharged into the atmosphere as presently occurs, to cause pollution of and damage to the atmosphere. Finally, it is to be understood that various modifications and/or alterations may be made to the apparatus without departing from the ambit of the present invention as defined in the claims appended hereto.