Abstract:
An apparatus for recovering a compressible refrigeration fluid from a refrigeration system and delivering the recovered fluid to a receiver as disclosed. The apparatus includes a discriminator tank for discriminating between influent liquid phase fluid and gas phase fluid. Liquid phase fluid is directed to the receiver. Gas phase fluid is condensed and directed to the receiver. The apparatus further includes a safety tank for preventing overfilling of the receiver and a compressor particularly adapted to refrigerant recovery.

Description:
TECHNICAL FIELD 
     The present invention pertains to the art of refrigeration systems. 
     BACKGROUND 
     In view of global concern regarding the environmental consequences attending the release of chlorofluorocarbon refrigerants into the atmosphere, there is now world-wide agreement regarding regulation of the production and use of chlorofluorocarbons. As a result of this regulation, the cost of chlorofluorocarbon refrigerants is expected to rise dramatically. 
     Accordingly, there has arisen an interest in recovering refrigerant fluids. Commonly assigned U.S. Pat. No. 4,766,733, the disclosure of which is incorporated herein by reference, describes an apparatus for recovering chlorofluorocarbon refrigerants. 
     SUMMARY OF THE INVENTION 
     An apparatus for recovering a compressible refrigeration fluid from a refrigeration system and delivering the recovered fluid to a refrigerant receiver is disclosed. The apparatus includes discriminator means for discriminating between gas phase fluid and liquid phase fluid, first conduit means for directing a stream of fluid from the refrigerant system to the discriminator, and second conduit means for directing a stream of liquid phase fluid from the discriminator means to the receiver. The apparatus further includes means for condensing a stream of gas phase fluid from the discriminator means to form a low pressure stream of substantially liquid phase fluid, third conduit means for directing the low pressure stream of substantially liquid phase fluid from the means for condensing to the receiver means, and vent means for directing a stream of fluid from the receiver to the means for condensing. The apparatus of the present invention provides improved efficiency compared to the apparatus described in U.S. Pat. No.4,766,733 and allows refrigerant to be removed from the refrigeration unit in significantly less time than possible with the prior art apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a schematic diagram of the apparatus of the present invention. 
     FIG. 2 shows a schematic top view of the compressor of the present invention. 
     FIG. 3 shows a cross sectional view of a portion of the compressor of the present invention. 
     FIG. 4 shows a cross sectional view of a portion of the compressor of the present invention. 
     FIG. 5 shows a cross sectional view of a portion of the compressor of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The apparatus of the present invention allows recovery of a compressible refrigeration fluid from a refrigeration system 2 and delivery of the recovered fluid to a refrigerant receiver 6. The refrigeration system includes a port 4, the receiver includes first port 8 and second port 10. 
     The apparatus of the present invention includes a discriminator chamber 12. The discriminator chamber 12 includes an inlet port 14, a liquid inlet port 15, a liquid outlet port 16, and a gas outlet port 18. Conduit 20 provides a fluid flow connection between refrigeration system port 4 and inlet port 14 of the discriminator chamber 12. A valve 22 allows control of flow through conduit 20 and a filter dryer 24 allows removal of moisture and particulate contaminants from the refrigerant removed from the refrigeration system 2. A conduit 26 is provided for directing liquid phase refrigeration fluid from port 16 of discriminator chamber 12 to port 8 of receiver 6. Conduit 26 is provided with a solenoid valve 28 for controlling flow through conduit 26 and an actuator 30 for opening and closing solenoid valve 28. 
     The apparatus of the present invention includes a compressor 32, a condenser 34 and a back pressure regulator 36 for condensing gas phase refrigerant fluid and providing a low pressure stream of substantially liquid phase fluid to conduit 26. Conduit 38 allows gas phase refrigerant fluid to flow from port 18 of discriminator chamber 12 to compressor 32. Conduit 38 is provided with a solenoid valve 40 for controlling flow through conduit 38. An actuator 42 is provided for opening and closing valve 40. Conduit 44 establishes a fluid flow connection between compressor 32 and condenser 34. Fan 46 provides a flow of air for removing heat from condensor 34. Conduit 48 establishes a fluid flow connection between the condenser 34 and the back pressure regulator 36. Conduit 50 establishes a fluid flow connection between back pressure regulator 36 and conduit 26. 
     The compressor 32 may comprise a conventional refrigerant compressor or a compressor of the present invention. Referring to FIGS. 2 and 3, a compressor of the present invention includes a tubular cylinder wall 102. The cylinder wall 102 comprises stainless steel. The cylinder head 104 enclosed one end of the tubular cylinder wall 102. The cylinder head 104 is provided with an intake port 106 and an outlet port 108 as well as an intake valve and outlet valve (not shown) for controlling flow through intake port 106 and outlet port 108. A piston 110 is slidably received within the tubular cylinder wall 102. An annular seal 112 circumscribes the piston. Annular seal 112 is a bi-directional self lubricating annular seal for sealing between the piston 110 and tubular cylinder wall 102 so that the apparatus of the present invention provides a high pressure outlet stroke and a vacuum intake stroke. A piston ring 113 is provided to maintain piston 110 axially aligned within the tubular wall 102. A piston rod 114 is provided for reciprocally moving the piston within the tubular cylinder wall 102. The piston rod 114 is rotably mounted on wrist pin 116. Wrist pin 116 is eccentrically secured to member 118. Shaft 120 is provided for rotating member 118. Gears 122 and 124 couple shaft 120 with the output shaft 126 of motor 128. 
     FIG. 4 shows one embodiment of the self lubricating bi-directional annular seal of the compressor 32 of present invention. Piston 110 defines an annular groove 130 which circumscribes the piston. Annular seal 112 is disposed within groove 130. Preferably, the annular seal 112 comprises a graphite or carbon filled flouropolymer, e.g. polytetrafluoroethylene. A chemically resistant elastomeric ring 132 urges piston ring 112 towards cylinder wall 102 to provide a bi-directional seal. Preferably, the elastomeric ring 132 comprises a chlorosulfonated polyethylene elastomer or a polychloroprene elastomer. 
     An alternative embodiment of the compressor 32 is shown in FIG. 5 in which two annular grooves 134 and 140 circumscribe piston 110. A pair of chemically resistant unidirectional seals 136 and 142 are disposed in grooves 134 and 140 respectively. Resilient members 138 and 144 urge seals 136 and 142 respectively toward tubular cylinder wall 102. 
     Valve 28 is normally closed and valve 40 is normally open. The discriminator chamber 12 includes float sensor 52 for sensing the level of liquid phase refrigerant fluid in the discriminator chamber 12. Sensor 52 is responsive to the level of liquid phase refrigerant fluid in the discrimination chamber 12 and provides a control signal if the discriminator chamber 12 is full of liquid phase refrigerant fluid. Actuators 30 and 42 are responsive to the control signal provided by sensor 52. In response to the control signal, actuator 42 closes valve 40 to prevent liquid from flowing from the discriminator chamber 12 to the compressor 32 and opens valve 28 to allow the liquid to drain from the discriminator chamber 12 through conduit 26 to receiver 6. 
     A bypass conduit 56 is provided to allow fluid to flow directly from condenser 34 to inlet port 8 of receiver 6. The bypass conduit 56 is provided with a solenoid valve 58 for controlling flow through conduit 56. An actuator 60 is provided to open and close solenoid valve 58. Valve 58 is normally closed. A pressure sensor 62 is responsive to the pressure within discriminator chamber 12 and provides a control signal if the pressure in discriminator chamber 12 falls below a predetermined value. Actuator 60 is responsive to the control signal from pressure sensor 62 and opens valve 58 in response to the control signal. 
     The recovery apparatus of the present invention includes a safety chamber 64. Safety chamber 64 includes an inlet port 66, a gas outlet port 68 and a liquid outlet port 70. A conduit 72 is provided for allowing fluid flow between port 10 of receiver 6 and inlet port 66 of safety chamber 64. Conduit 72 is provided with a solenoid valve 74 for controlling flow through conduit 72. An actuator 76 is provided for opening and closing solenoid valve 74. Conduit 78 allows fluid to flow from gas exit port 68 of safety chamber 64 to conduit 38 and on to compressor 32. Conduit 80 allows fluid to flow from liquid exit port 70 of safety chamber 64 to liquid inlet port 15 of discriminator chamber 12. Conduit 80 is provided with a solenoid valve 82 for controlling flow through conduit 80. An actuator 84 is provided for opening and closing solenoid valve 82. 
     Inlet tube 86 extends into receiver 6 through port 10 of receiver 6 to an open end 88. 
     If the level of liquid phase refrigerant within receiver 6 is below the open end 88 of inlet tube 86, gas phase refrigerant fluid flows through conduit 72, safety chamber 64 and conduit 78 to compressor 32. 
     As the receiver fills with refrigeration fluid, the liquid level rises until the liquid level reaches the end 88 of inlet tube 86. Once the liquid level in the receiver is at the level of the open end 88 of inlet tube 86, the introduction of additional refrigeration fluid into receiver 6 will result in liquid phase refrigerant being forced through conduit 72 and into inlet port 66 of safety chamber 64. Sensor 90 within safety chamber 64 is responsive to liquid level within safety chamber 64. When liquid phase refrigerant enters safety chamber 64, sensor 90 provides a control signal. Actuators 30, 42, and 76 and switch 33 are responsive to sensor 90 and close valves 28, 40 and 74 and cut power to the compressor 32, respectively, in response to the control signal from sensor 90. 
     The apparatus of the present invention has two modes of operation and may be used to recover refrigeration fluid from a refrigeration system (recovery mode) and to charge refrigeration fluid from receiver to a refrigeration system (charging mode). 
     In the recovery mode compressor 32 and condensor fan 46 are turned on. Compressor 32 lowers the pressure in receiver 6 as well as compressing the influent stream 38 of gas phase fluid. Fluid evaporates from the receiver 6 is directed through conduit 72, inlet 66 chamber 64, outlet 68, conduit 78 and is combined with influent gas stream 38. Evaporation of refrigerant fluid from receiver 6 lowers the temperature of the liquid phase fluid remaining in receiver 6. The apparatus maintains a pressure differential to drive fluid from refrigeration unit 2 to receiver 6 until substantially all refrigerant has been removed from the refrigeration unit. 
     In the charging mode, the compressor 32 is turned on, fan 46 is turned off, back pressure regulator 36 is closed and valve 58 is open. Fluid is evaporated from the receiver and compressed in the compressor 32 to form a high pressure elevated temperature stream of refrigerant fluid. The high pressure elevated temperature stream of refrigerant is introduced to the receiver 6 through conduit 26 to increase the pressure within receiver 6 and force fluid from receiver 6 through a conduit (not shown) to the refrigeration system 2 being charged. 
     The discrimination chamber of the present invention allows liquid phase refrigerant to bypass the compressor, condensor and backpressure regulator as it passes from the refrigeration unit to the refrigerant receiver and thereby allows refrigerant to be removed from the refrigeration unit in significantly less time than possible with the apparatus described in U.S. Pat. No. 4,766,733. 
     Conventional refrigerant receivers are provided with a safety valve in order to preclude the generation of internal pressures within a refrigerant receiver that exceed the pressure rating of the container. The safety valve opens at a predetermined maximum pressure that is below the maximum pressure rating of the receiver. In order to avoid generating internal pressures with a receiver that would trigger the safety valve, the amount of refrigerant introduced to a receiver must be controlled. Conventionally, refrigerant containers are filled by weight. In the context of recovering refrigerant from refrigeration units in the field, a weighing apparatus constitutes a cumbersome additional piece of equipment to transport. The safety chamber of the present invention allows control of the amount of refrigerant introduced to the receiver without requiring any equipment in addition to the apparatus of the present invention. 
     The features of the compressor of the present invention offer several benefits which are particularly advantageous in the context of refrigerant recovery. Conventional refrigeration compressors are typically heavy, cumbersome devices which include a thick cast iron cylinder wall. The compressors of the present invention is light weight and easily portable. 
     Typically the materials of construction of conventional refrigerant compressors are not reactant to impurities, e.g. acids, present in used refrigerant fluids. The compressor of the present invention is adapted for transferring contaminated refrigerants. 
     Conventional refrigeration compressors operate in closed loop refrigeration systems in which a lubricating oil migrates through the loop and continuously lubricates the compressor. The recovery of used refrigerant is inherently an open loop process. Each time the used refrigerant passes from the refrigeration system through the compressor into a receiver refrigerant compressor of the present invention is self lubricating. 
     Conventional refrigerant compressor include unidirectional seals and are unable to provide a vacuum intake stroke. The seals on the piston of the refrigerant compressor of the present invention are bi-directional and the refrigerant compressor of the present invention can therefore be used to pull the inlet pressure below atmospheric pressure, and allow a refrigerant system to be completely emptied of used refrigerant. 
     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.