US3664147A

US3664147A - Purge apparatus for refrigeration system

Info

Publication number: US3664147A
Application number: US65217A
Authority: US
Inventors: John G Blackmon
Original assignee: Carolina Products Inc
Current assignee: Carolina Products Inc
Priority date: 1970-08-19
Filing date: 1970-08-19
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23

Abstract

A purge apparatus for removing foreign non-condensable gases from a refrigeration system including a closed vessel adapted to receive the foreign gases together with a portion of the refrigerant from the high pressure region of the system. The vessel is cooled to condense the refrigerant, and a float actuated electrical switch is provided within the vessel to open a first valve for discharging the condensed refrigerant upon the refrigerant reaching a predetermined level, and a second valve for venting the non-condensable gases to the atmosphere upon a drop in the refrigerant level. The discharged condensed refrigerant is utilized to cool the vessel by evaporating the same in an area about the outer walls of the vessel, and then returned to the low pressure region of the system.

Description

United States Patent [54] PURGEAPPARATUSFOR REFRIGERATION SYSTEM [72] Inventor:

Primary Examiner-William E. Wayner Att0rneyParrott, Bell, Seltzer, Park & Gibson John G. Blackmon, Charlotte, NC.

ABSTRACT [73] Assignee: Carolina Products, Inc., Charlotte, NC

A purge apparatus for removing foreign non-condensable gases from a refrigeration system including a closed vessel adapted to receive the foreign gases together with a portion of the refrigerant from the high pressure region of the system. The vessel is cooled to condense the refrigerant, and a float actuated electrical switch is provided within the vessel to open a first valve for discharging the condensed refrigerant upon 5 5 9m wa .0% 54 2 BF 2 m 0 m m 7 u u 9 n n w 7 1 u w mm" 5 h A 6 m mm Q m In N in el O .0 m. d m P S M F A UhF l 1]] 2 1 2 00 2 2 555 l l[[ the refrigerant reaching a predetermined level, and a second References Cited valve for venting the non-condensable gases to the atv .e wbhm g ti ma ma s se .m m.m e wg e m mm 3 m mm w. o nm mtuw r 0 g w bb i? m mun m m ftm m m 6 h d .m mm D. eu l mm a C d6 .1 4 am 1 nmmme m m u ewmm r a mf e m WdW e mwm mCevW XXXfiX 544 5 65m M22u 266 "2 m m A m mL P m ma S was mm m n mn e kvwoke m mm m S MfdM-u D ZBEZE mgoilfil N 40346 U 99999 HHHHH 3 252 11 l 7904 3 920 42503 6630 2 23 PATENTEDmzamz I 3.664.147

I SHEET 2 UF 2 Y ii z 24 y INVENTOR. no 25 n5 J'oHN G BLACKMON ATTORNEYS PURGE APPARATUS FOR REFRIGERATION SYSTEM The present invention relates to a refrigeration system, and more particularly to an apparatus for purging non-condensable gases from the system.

In a conventional refrigeration system, particularly in low pressure centrifugal compressor systems, the leakage of air and other foreign gases into the system is a recognized problem. Such gases reduce the efficiency of the system since they tend to elevate the total pressure in the condenser, and thus more power is required from the compressor per unit of refrigeration. Also these foreign gases, which are largely noncondensable, tend to cling to the condenser tubes thereby reducing the total condensing surface area.

To remove these foreign gases from the system, it is common practice to draw a mixture of the gaseous refrigerant and foreign gases from the high pressure region in the condenser or receiver where they normally accummulate, condense the refrigerant and any water vapor by cooling or by compression and cooling, vent off the non-condensables, separate and drain the water, and return the condensed refrigerant to the low pressure region of the system. The purge unit itself typically comprises a separation chamber wherein the non-condensables gather above the liquid refrigerant and water. A pressure actuated mechanical relief valve automatically opens to vent the non-condensables, and a manual drain is provided to drain off the water which floats on top of the liquid refrigerant. A mechanical valve adjacent the bottom of the unit is opened by a float when the refrigerant reaches a predetermined level to drain the refrigerant and return it to the system.

The above purging system has presented a serious proble in that the mechanical valves utilized in the purge unit to vent the non-condensable gases and drain the condensed refrigerant have a tendency to stick either in the open or closed position. A malfunction of this type can result in the loss of the refrigerant, and usually necessitates stopping the entire refrigeration system to repair the valves. Obviously, this could present a serious problem when perishable goods are under refrigeration.

In another type known purge apparatus, the return line for the condensed refrigerant leads directly from the purge unit back into the condenser such that the liquid refrigerant is free to pass to and fro therebetween. Thus the liquid refrigerant serves as the seal in preventing the non-condensable gases from returning to the condenser, and the relative pressures in the purge unit and condenser must be closely controlled to maintain the refrigerant in the return line. Also, this type unit must be primed with liquid refrigerant to initiate operation of the apparatus.

It is accordingly an object of the present invention to provide a purging apparatus of high reliability and efficiency. More particularly, it is an object to provide a purging apparatus having an electrical float switch operatively connected to solenoid operated valves for venting the non-condensables and draining the refrigerant, with the drain valve acting to insure the retention of at least a portion of the liquified refrigerant in the purge unit to act as a seal in preventing the return of the non-condensable gases to the system.

It is a further object of the present invention to provide a purging apparatus which may be operated while the entire refrigeration system is running, or which may be operated independently of the refrigeration system.

It is a further object of the present invention to provide an auxiliary compressor which may be utilized to operate the purge apparatus when the refrigeration system is not operating and which may be utilized independently of the main refrigeration system to accomplish other functions periodically required for the proper operation of the system.

It is still another object of the present invention to utilize the condensed refrigerant in the purge apparatus to cool the same and thereby facilitate condensation of the gaseous refrigerant and water vapor entering the apparatus.

These and other objects and advantages of the present invention are achieved in the embodiment illustrated herein by the provision of a purge apparatus which comprises a closed vessel having an inlet for introducing the gaseous refrigerant and non-condensables from the high pressure region of the system thereinto, a first outlet adjacent the bottom of the vessel and including an electrically operable valve for discharging the condensed refrigerant therefrom, and a second outlet adjacent the top of the vessel and including an electrically operable valve for venting the non-condensable gases therefrom. A magnet equipped float switch positioned within the vessel opens the first outlet valve upon the liquid refrigerant reaching a predetermined level, and opens the second outlet valve upon the liquid dropping below the predetermined level. The walls of the vessel are cooled to facilitate condensation of the entering refrigerant and any water vapor, and such cooling is accomplished by means of an outer shell surrounding the vessel in spaced apart relation to define an enclosed area therebetween. The condensed refrigerant discharged from the vessel is directed into the enclosed area and through a restrictive orifice such that the pressure is reduced to about that in the low pressure region and the refrigerant at least partially evaporates within the area and thereby cools the outer walls of the vessel.

Some of the objects and advantages of the invention having been stated, others will appear as the description proceeds when taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a typical centrifugal refrigeration system incorporating the purging apparatus of the present invention;

FIG. 2 is a fragmentary schematic view similar to F IG. 1 and illustrating the manner in which oil is removed from the system;

FIG. 3 is a fragmentary schematic view similar to FIG. 2 and illustrating the manner in which oil is added to the system;

FIG. 4 is a similar fragmentary schematic view illustrating the manner for removing the refrigerant from the system;

FIG. 5 is a similar fragmentary schematic view illustrating the manner for charging refrigerant to the system; and

FIG. 6 is a schematic wiring diagram for the refrigeration system.

Referring more particularly to the drawings, a refrigeration system embodying the novel features of the present invention is illustrated schematically in FIG. 1, and includes a centrifugal compressor 10, a condenser 12, and a cooler or evaporator 14. A line 16 conducts the condensed refrigerant betwen the condenser and evaporator, and includes a conventional restrictive means (not shown) such as an expansion valve, which divides the system into a high pressure region in the condenser and a low pressure region in the evaporator. The line 18 provides a path of flow for the gaseous refrigerant formed in the evaporator to the compressor 10, where the pressure of the refrigerant is elevated. The pressurized gaseous refrigerant is then discharged through line 20 to the condenser to complete the refrigeration cycle. In the illustrated embodiment, the compressor 10 includes an oil reservoir 21 having a manually controlled discharge valve 22, and the evaporator 14 includes a refrigerant storage tank 23 having a manually controlled discharge valve 24.

Since the low pressure region of the above described refrigeration system is commonly below atmospheric pressure, it is subject to air-in leakage. The water vapor and non-condensable gases which enter with the air collect in the upper portion of the condenser 12 and mix with the gaseous refrigerant. A conduit 26 and a manually operable valve 27 are provided for removing these gases from the condenser, and during normal operations, the gases pass through the check valve 28 to the conduit 29. The conduit 29 leads through the condensing apparatus 30 where the refrigerant and water vapor are at least partially condensed, and then into the conduit 32. The condensing apparatus 30 may be supplied with cooling water or other cooling medium through the lines 34 and 36 to facilitate the cooling operation.

The purge apparatus comprises a closed vessel 40 which may, for example, be in the configuration of an elongated tubular member with closed parallel opposte ends. The vessel includes an inlet at 42 for the conduit 32 such that the refrigerant and foreign gases may be received therein. The refrigerant and water vapor will have been at least partially condensed in the condensing apparatus 30, and thus these components will enter the vessel 40 essentially in liquid form and collect at the bottom thereof. The water, being lighter than the condensed refrigerant, will float on top. The non-condensable gases entering the vessel will collect in the upper region thereof.

The vessel includes a first outlet 44 adjacent the bottom for draining the condensed refrigerant therefrom, a second outlet 46 adjacent the top for venting the non-condensable gases, and a third outlet 48 positioned at a level intermediate the first and second outlets for discharging any water floating on the top of the refrigerant. A manually removable cap 49 is operatively connected to the outlet 48 for the purpose hereinafter set forth. An outer shell 50 surrounds the vessel 40 in spaced apart relation to define an enclosed area 52 therebetween, and the shell includes an inlet 54, and an outlet 56.

The first outlet 44 of the vessel 40 is connected to a conduit 58 which leads through a valve 60 controlled by the solenoid 61, through an orifice or restriction 62, and into the area 52 via the inlet 54. The second outlet 46 adjacent the top of the vessel 40 is connected to a conduit 64 which leads through the valve 66 controlled by the solenoid 67, and then vents to the atmosphere. Positioned within the vessel is a float actuated electric switch 70 which is controlled by the level of the refrigerant and water. Generally, the switch 70 includes a magnet equipped float 75, and is designed to actuate a relay 72 (FIG. 6) upon a rise in liquid to a predetermined level. The relay 72 is operatively connected to the contact switches at 73 and 74. With the main control switch 77 closed in either the automatic or manual position, and the liquid level below the predetermined level, the contacts at 73 are open to de-energize solenoid 61 and close valve 60, and the contacts at 74 are closed such that solenoid 67 is actuated and valve 66 is open. Upon the liquid reaching the predetermined level, the float actuated switch 70 closes the relay 72, the contacts at 73 are closed to open valve 60, and the contacts at 74 are opened to close valve 66.

The switch 70 is of conventional design and includes the magnet equipped float 75 which moves with the liquid level. Upon reaching the predetermined level, the float is designed to close the contacts of the switch 70 which are positioned within sealed stem 76. A suitable switch of this type is manufactured by the Gems Company, Inc. of Farmington, Connectrcut.

In operation, the vessel 40 receives the partially condensed refrigerant and water vapor, as well as the non-condensable gases, through the inlet 42. The condensed refrigerant and water collect at the bottom until the float 75 is raised to a level sufficient to close the switch 70 and open the closed valve 60 in the manner described above. The condensed refrigerant then flows through conduit 58 and the restriction 62 and into the area 52 between the vessel and shell. The restriction 62 causes the pressure to drop within the area 52 to approximately the pressure in the low pressure region, and the refrigerant therein to evaporate. This in turn cools the walls of the vessel 40, lowering its temperature to approach that of the evaporator 14, and causing the refrigerant and water vapor not previously condensed in the apparatus 30 to be condensed in the vessel 40. The evaporated refrigerant in the area 52 is returned to the evaporator 14 of the main system via the outlet 56, conduit 78, and the manually controlled valve 79.

When the refrigerant level in the vessel 40 drops below the predetermined level, the float 75 opens switch 70 to close valve 60 and open valve 66 in the manner described above. The non-condensable gases which have accumulated above the liquid level then escape through the conduit 64 and vent to the atmosphere.

The water floating on top of the refrigerant may be periodically drained through outlet 48 by manually removing the cap 49. A sight glass of conventional design (not shown) could be operatively connected to the vessel 40 to facilitate observation of the water level.

The above described purging system is essentially automatic, and will operate whenever the compressor 10 of the main system is running, and the

valves

27 and 79 are opened. It is a further aspect of the present invention to provide a manually controlled system which is adapted to operate when the main refrigerating system is shut down. In this regard, a conduit 80 is connected in parallel with a portion of the conduit 26, and leads past a first manually controlled outlet valve 82, a valve 84 and controlling solenoid 85, through an auxiliary compressor 86, past a second manually controlled outlet valve 88, a check valve 90, and into the conduit 29. In addition, the outlet side ofthe compressor 86 is connected across a capillary tube 92 to the low pressure side of the system via the conduit 78 for the purposes set forth below.

The double pole throw switch 77 (FIG. 6) is provided for selectively operating the apparatus in either its automatic mode wherein an auxiliary compressor 86 is disengaged or its manual mode wherein the auxiliary compressor 86, which may for example be of the diaphragm type, is engaged for positive circulation of refrigerant through the purge system. The switch 77 also includes an off position wherein the purge system is shut down. The valve 84, which is closed during automatic operation, is open during manual operation, such that the gases in the compressor 12 are drawn through the

conduits

26 and 80, and into the compressor 86. From the compressor 86, the gases pass through the check valve and into the conduit 29. The operation from this point is identical to the automatic system described above.

Viewing FIG. 6, it will be seen that the system may be provided with a number of pilot lights to visually indicate the mode of operation. In particular, the light 95 is energized during operation in either the automatic or manual mode, the light 96 is energized during manual operation, and the light 97 is energized whenever the float equipped switch 70 is closed. Also, a counter 98 may be provided to record the number of times the switch 70 is closed to thereby indicate the cumulative cycles of the apparatus and thus the amount of air-in leakage.

As indicated above, the valve 84 at the inlet side of the compressor 86 is closed during non operation of the compressor. During such periods, the capillary 92 permits any pressurized refrigerant in the compressor to slowly exhaust into the conduit 78 until the pressure in the compressor equals that in the evaporator 14. This reduces the power required to start the compressor 86, and thus reduces the required size of the compressor motor.

In the apparatus as described above, it is periodically desired to remove and change the oil in the oil reservoir 21 of the compressor 10. This may be accomplished without contaminating the refrigerant in the manner illustrated in FIGS. 2 and 3. In particular, the valve 27 on the condenser 12 is closed, and line 102, which includes a sight glass 103, is connected between outlet valve 22 and an empty container 105. Line 106 is connected between the container and valve 82. The valves 82 and 88 are opened, the valve 22 on the oil reservoir is opened, and the apparatus is switched to manual operation such that the solenoid 85 is actuated and valve 84 is opened. This will also energize the compressor 86 and draw a vacuum on the container 105 to thereby draw the oil from the reservoir through line 102 and into the container 105. By viewing the sight glass 103, the operator will be able to determine when all of the oil has been removed and deposited in the container 105. When this has been accomplished, valve 22 is closed, and the switch 94 turned off to stop the compressor 86 and close valve 84. Upon closure of valves 82 and 88 the

lines

102 and 106 may be removed.

The connections required to return oil to the reservoir 21 are illustrated in FIG. 3. In this case, line 106 is connected to outlet valve 88, and valve 82 is opened to the atmosphere. The line 102 is again connected to the valve 22. After the valve 22 is opened, and the purge apparatus set to manual operation, the compressor 86 will operate to force the oil from the container 105 into the reservoir 21. By observing the sight glass 103, it may be determined when all of the oil has been returned.

The purging apparatus of the present invention is also adapted to facilitate removal of the refrigerant from the system in the event that major repair is required, note FIGS. 4 and 5. In this case, valve 27 on the condenser is closed, and line 110, leading from the storage tank 112, is connected to the valve 24 at the evaporator storage tank 23. Line 114 from the tank 112 is connected to valve 82. With the valves 82 and 88 open, and the entire apparatus switched to manual operation to open valve 84, the auxiliary compressor 86 will operate to remove the refrigerant from the evaporator 14 and fill the tank 112. The refrigerant can be viewed through a sight glass 115 to determine when all of the refrigerant has been removed. The system is then turned off,

valves

24, 82 and 88 are closed, and the lines 110 and 114 removed.

To recharge the refrigerant as shown in FIG. 5, line 110 is again connected to the valve 24, and line 114 is connected to valve 88. Valve 27 of the condenser and valve 24 at the evaporator are then opened. When the system is manually operated, the compressor 86 will force the refrigerant from the tank 112 back into the evaporator tank 23. When the

valves

24 and 88 are closed, and the lines 110 and 114 removed, the system is ready for normal operation.

In the drawings and specification, there has been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

Iclaim:

1. In a refrigeration system including a compressor, a relatively high pressure region including a condenser, and a relatively low pressure region including an evaporator, the combination herewith of a purge apparatus for removing non-condensable gases from the refrigerant comprising,

a separation vessel including an outer wall,

inlet means communicating with said high pressure region of the system for transferring refrigerant and non-condensable gases through said wall and into the vessel, and including condensing means for at least partially condensing the refrigerant before entry into said separation vessel,

first outlet means for transferring condensed refrigerant from said vessel to said low pressure region and including an electrically operable valve, orifice means for creating a pressure differential to at least partially evaporate the refrigerant transferred thereacross, and means for contacting the vessel outer wall with the evaporated refrigerant to cool the vessel and thereby condense the refrigerant therein,

second outlet means adjacent the top of the vessel and including an electrically operable valve for discharging the non-condensable gases therefrom, and

electrical switch means operatively controlled by the level of the condensed refrigerant in the vessel and connected to said first outlet valve and said second outlet valve for opening said first outlet valve only when the refrigerant reaches a predetermined level and for opening said second outlet valve only when the refrigerant is below said predetermined level.

2. A refrigeration system as defined in claim 1 wherein said means for contacting the vessel outer wall with the evaporated refrigerant includes a shell surrounding said vessel wall in spaced apart relation to define an enclosed area therebetween.

3. A refrigeration system as defined in claim 1 wherein said separation vessel includes third outlet means positioned at a level intermediate said first and second outlet means for discharging condensed water which may enter the system.

4. A refrigeration system as defined in claim 1 wherein said inlet means includes a conduit having first and second parallel paths, means for independently connecting either one of said first and second paths into said inlet means such that the gaseous refrigerant and non-condensable gases are transferred through the selected path, and an auxiliary compressor operatively connected in one of said paths such that the refrigerant and non-condensable gases may be transferred into said vessel by said auxiliary compressor.

5. A refrigeration system as defined in claim 4 further comprising means for disconnecting said auxiliary compressor from the system whereby the auxiliary compressor may be used independently thereof.

6. A refrigeration system as defined in claim 4 wherein said auxiliary compressor includes an inlet side and an outlet side, said inlet side including valve means for closing the same during non-operation of the auxiliary compressor and said outlet side including capillary means for venting the auxiliary compressor into said evaporator during periods of non-operation of the auxiliary compressor.

7. A purge apparatus for removing non-condensable gases from the refrigerant in a refrigeration system having a relatively high pressure region and a relatively low pressure region comprising,

a closed vessel,

inlet means for introducing the refrigerant containing noncondensable gases from the high pressure region into said closed vessel and including condensing means for at least partially condensing the refrigerant before entry into said closed vessel,

means for cooling said vessel to condense the refrigerant therein,

an electric switch operatively controlled by the level of the condensed refrigerant in said vessel, first outlet means including an electrically operable valve operatively controlled by said switch for discharging a portion of the condensed refrigerant from the vessel into said low pressure region upon the rise of condensed refrigerant above a predetermined level, and second outlet means including an electrically operable valve operatively controlled by said switch for discharging the non-condensable gases from said vessel upon a drop in condensed refrigerant level below said predetermined level. 8. The apparatus as defined in claim 7 wherein said cooling means comprises an outer shell surrounding said vessel in spaced apart relation to define an enclosed area therebetween, and said first outlet means includes means for admitting the condensed refrigerant into said enclosed area and orifice means for maintaining the pressure in said enclosed area substantially equal to that in said low pressure region such that the refrigerant at least partially evaporates therein.

9. The apparatus as defined in claim 8 wherein said electric switch includes a magnetic float in said vessel.

10. A method of purging a refrigeration system to remove non-condensable gases from the refrigerant comprising the steps of,

withdrawing gaseous refrigerant and non-condensable gases from a relatively high pressure region of the refrigeration system wherein the non-condensable gases accumulate,

cooling the refrigerant and non-condensable gases to at least partially condense the refrigerant, then transferring the same to a separation vessel,

cooling the vessel to condense the refrigerant by withdrawing a portion of the condensed refrigerant from the vessel upon its reaching a predetermined level, reducing the pressure of the withdrawn refrigerant to at least partially evaporate the same, and contacting the walls of said vessel with the evaporated refrigerant, and

venting the vessel to the atmosphere upon the refrigerant dropping below said predetermined level to exhaust the non-condensable gases.

11. The method according to claim 10 including the further step of returning the evaporated refrigeration to a relatively low pressure region of the system after contacting the walls of the vessel.

12. In a refrigeration system including a compressor, a relatively high pressure region including a condenser, and a relatively low pressure region including an evaporator, the combination herewith of a purge apparatus for removing non-condensable gases from the refrigerant comprising,

a separation vessel including an outer wall,

inlet means communicating with said high pressure region of the system for transferring gaseous refrigerant and non-condensable gases through said wall and into the vessel and including condensing means for at least partially condensing the refrigerant before entry into said separation vessel,

first outlet means for transferring condensed refrigerant from said vessel to said low pressure region and including an electrically operable valve,

13. A purge apparatus for removing non-condensable gases from the refrigerant in a refrigeration system having a relatively high pressure region and a relatively low pressure region comprising,

a closed vessel,

an electric switch operatively controlled by the level of the condensed refrigerant in said vessel, first outlet means including an electrically operable valve operatively controlled by said switch for discharging a 10 portion of the condensed refrigerant from the vessel into said low pressure region upon the rise of condensed refrigerant above a predetermined level, and second outlet means including an electrically operable valve operatively controlled by said switch for discharging the non-condensable gases from said vessel upon a drop in condensed refrigerant level below said predetermined level. 14. A method of purging a refrigeration system to remove non-condensable gases from the refrigerant comprising the steps of,

withdrawing gaseous refrigerant and non-condensable gases from a relatively high pressure region of the refrigeration system wherein the non-condensable gases accummulate. cooling the refrigerant and non-condensable gases to at least partially condense the refrigerant then transferring the withdrawn refrigerant and non-condensable gases to a separation vessel, withdrawing a portion of liquid refrigerant from the vessel upon the liquid refrigerant reaching a predetermined level therewithin, and

venting the vessel to the atmosphere upon the liquid refrigerant dropping below said predetermined level to exhaust the non-condensable gases.

Claims

1. In a refrigeration system including a compressor, a relatively high pressure region including a condenser, and a relatively low pressure region including an evaporator, the combination herewith of a purge apparatus for removing noncondensable gases from the refrigerant comprising, a separation vessel including an outer wall, inlet means communicating with said high pressure region of the system for transferring refrigerant and non-condensable gases through said wall and into the vessel, and including condensing means for at least partially condensing the refrigerant before entry into said separation vessel, first outlet means for transferring condensed refrigerant from said vessel to said low pressure region and including an electrically operable valve, orifice means for creating a pressure differential to at least partially evaporate the refrigerant transferred thereacross, and means for contacting the vessel outer wall with the evaporated refrigerant to cool the vessel and thereby condense the refrigerant therein, second outlet means adjacent the top of the vessel and including an electrically operable valve for discharging the noncondensable gases therefrom, and electrical switch means operatively controlled by the level of the condensed refrigerant in the vessel and connected to said first outlet valve and said second outlet valve for opening said first outlet valve only when the refrigerant reaches a predetermined level and for opening said second outlet valve only when the refrigerant is below said predetermined level.

7. A purge apparatus for removing non-condensable gases from the refrigerant in a refrigeration system having a relatively high pressure region and a relatively low pressure region comprising, a closed vessel, inlet means for introducing the refrigerant containing non-condensable gases from the high pressure region into said closed vessel and including condensing means for at least partially condensing the refrigerant before entry into said closed vessel, means for cooling said vessel to condense the refrigerant therein, an electric switch operatively controlled by the level of the condensed refrigerant in said vessel, first outlet means includinG an electrically operable valve operatively controlled by said switch for discharging a portion of the condensed refrigerant from the vessel into said low pressure region upon the rise of condensed refrigerant above a predetermined level, and second outlet means including an electrically operable valve operatively controlled by said switch for discharging the non-condensable gases from said vessel upon a drop in condensed refrigerant level below said predetermined level.

8. The apparatus as defined in claim 7 wherein said cooling means comprises an outer shell surrounding said vessel in spaced apart relation to define an enclosed area therebetween, and said first outlet means includes means for admitting the condensed refrigerant into said enclosed area and orifice means for maintaining the pressure in said enclosed area substantially equal to that in said low pressure region such that the refrigerant at least partially evaporates therein.

10. A method of purging a refrigeration system to remove non-condensable gases from the refrigerant comprising the steps of, withdrawing gaseous refrigerant and non-condensable gases from a relatively high pressure region of the refrigeration system wherein the non-condensable gases accumulate, cooling the refrigerant and non-condensable gases to at least partially condense the refrigerant, then transferring the same to a separation vessel, cooling the vessel to condense the refrigerant by withdrawing a portion of the condensed refrigerant from the vessel upon its reaching a predetermined level, reducing the pressure of the withdrawn refrigerant to at least partially evaporate the same, and contacting the walls of said vessel with the evaporated refrigerant, and venting the vessel to the atmosphere upon the refrigerant dropping below said predetermined level to exhaust the non-condensable gases.

12. In a refrigeration system including a compressor, a relatively high pressure region including a condenser, and a relatively low pressure region including an evaporator, the combination herewith of a purge apparatus for removing non-condensable gases from the refrigerant comprising, a separation vessel including an outer wall, inlet means communicating with said high pressure region of the system for transferring gaseous refrigerant and non-condensable gases through said wall and into the vessel and including condensing means for at least partially condensing the refrigerant before entry into said separation vessel, first outlet means for transferring condensed refrigerant from said vessel to said low pressure region and including an electrically operable valve, second outlet means adjacent the top of the vessel and including an electrically operable valve for discharging the non-condensable gases therefrom, and electrical switch means operatively controlled by the level of the condensed refrigerant in the vessel and connected to said first outlet valve and said second outlet valve for opening said first outlet valve only when the refrigerant reaches a predetermined level and for opening said second outlet valve only when the refrigerant is below said predetermined level.

13. A purge apparatus for removing non-condensable gases from the refrigerant in a refrigeration system having a relatively high pressure region and a relatively low pressure region comprising, a closed vessel, inlet means for introducing the refrigerant containing non-condensable gases from the high pressure region into said closed vessel and including condensing means for at least partially condensing the refrigerant before entry into said closed vessel, an electric switch operatively cOntrolled by the level of the condensed refrigerant in said vessel, first outlet means including an electrically operable valve operatively controlled by said switch for discharging a portion of the condensed refrigerant from the vessel into said low pressure region upon the rise of condensed refrigerant above a predetermined level, and second outlet means including an electrically operable valve operatively controlled by said switch for discharging the non-condensable gases from said vessel upon a drop in condensed refrigerant level below said predetermined level.

14. A method of purging a refrigeration system to remove non-condensable gases from the refrigerant comprising the steps of, withdrawing gaseous refrigerant and non-condensable gases from a relatively high pressure region of the refrigeration system wherein the non-condensable gases accummulate, cooling the refrigerant and non-condensable gases to at least partially condense the refrigerant then transferring the withdrawn refrigerant and non-condensable gases to a separation vessel, withdrawing a portion of liquid refrigerant from the vessel upon the liquid refrigerant reaching a predetermined level therewithin, and venting the vessel to the atmosphere upon the liquid refrigerant dropping below said predetermined level to exhaust the non-condensable gases.