Abstract:
An injector cooler control system which controls the flow of refrigerant from a common receiver that ties a common refrigeration plant to more than one injector cooler systems. The control system limits the amount of liquid refrigerant entering a cooler surge tank by limiting the amount of liquid refrigerant passing from the receiver through an injector valve, thus preventing liquid carryover to the compressor of a common refrigeration plant.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the operation of the refrigerant control system in an injector cooler and more particularly to the control of the refrigerant system when more than one injector type cooler is connected to a common refrigerant plant. 
     Heretofore, industries that use injector type cooler refrigeration systems, such as the soft drink industry, have had to use separate refrigeration plants for each injector type cooler. Individual refrigeration plants had to be used because the injector cooler system is a low side critical fixed charged unit which passed the entire charge, and thus cannot be connected to other injector coolers through a common refrigeration plant. 
     SUMMARY 
     The present invention relates to a new and improved control system for an injector type cooler in which two or more injector coolers are connected to a common refrigeration plant. 
     In the present invention liquid level control systems detect the liquid refrigerant level in a surge tank, which is located on the suction side of the compressor, and control the flow of refrigerant from a common receiver. The entire quantity of refrigerant stored in the receiver is prevented from being passed into the low side of the refrigerant system by closing a control valve in the primary liquid loop and opening a control valve in the bypass vapor loop when a high level control point is reached in the surge tank. Thus, the liquid from the receiver will no longer flow through the injector nozzle and be carried over into the compressor after flooding the surge vessel. However, vapor will now enter the injector nozzle from the receiver through the bypass loop, and draw down liquid refrigerant from the surge tank. When the level in the surge tank reaches a low level control point, the control system will close the vapor bypass loop and open the primary liquid loop. 
     It is therefore the principal object of this invention to provide means to connect two or more injector coolers into a common refrigeration system. 
     It is another object of this invention to provide a means to prevent carry over into the low side of the compressor of a common refrigeration system. 
     It is still another object of this invention to provide means to save electric energy in injector cooler systems by combining many refrigeration systems with individual components into a common refrigeration system. 
     It is a further object of this invention to provide continued normal operation of some of the connected injector coolers while other injector coolers are removed from service for maintenance. 
     It is a still further object of this invention to provide means for starting up an injector cooler system with a low load or during a cold morning start up situation. 
     In accordance with these and other objects which will be apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic view of the present invention connected to a refrigeration system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in detail to the drawing, wherein an embodiment of the present invention is shown, FIG. 1 illustrates an injector cooler system having at least two injector type coolers, A and B, connected to a common refrigeration system. Each injector cooler system generally has a heat exchange vessel 10 with cooling plates 14 connected to a surge tank 12 through inlet line 16 and outlet line 18. The heat exchanger 10 also has an inlet 22 and outlet 24 to pass the fluid to be cooled through the shell side of the heat exchanger 10. 
     The surge tank 12 is constructed such that it has two outlets, a liquid outlet 26 and a vapor outlet 28, and one inlet 32 connectable to the outlet 18 of the heat exchanger. The surge tank 12 also has at least one level detector device 30 for detecting the liquid refrigerant level in the surge tank 12. 
     The inlet line 16 of the heat exchanger 10 is connected to an injector nozzle 20 which draws down liquid from the surge tank 12 through outlet 26 when fluid flows through the injector nozzle 20. The upstream side of the injector nozzle 20 is connected to a receiver tank 40, which is common to all injector cooler systems, through two generally parallel pipe systems. One pipe system is a liquid transfer pipe 34 with a control valve 36 therein. The other pipe system is a vapor transfer pipe 38 which has a control valve 42 therein. Both liquid transfer pipe 34 and vapor transfer pipe 38 are tied together upstream of the injector nozzle 20 by a pipe tee 44, for example. 
     Generally, the upstream portion 46 of the liquid transfer pipe 34 extends near the bottom of the receiver 40, to insure a liquid suction, while the upstream portion 48 of the vapor transfer line 38 only extends to near the top of the receiver 40, to insure a vapor suction. 
     The refrigerant and vapor exiting the outlet 18 of the heat exchanger 10 enters the surge tank 12 through inlet 32. In the surge tank 10, the liquid refrigerant, for example ammonia, drops down to the bottom of the tank to be recycled through the injector nozzle 20 into the tube side 14 of the heat exchanger, while the vapor is drawn out through vapor outlet 28 to the suction of the compressor 50 where it is compressed. The discharge of the compressor 50 flows through pipe 52 to the evaporative condenser 54 where the compressed vapor is liquified and passes through pipe 56 to the common receiver 40. 
     In operation, the present invention is as follows: Vapor control valve 42 is normally closed and liquid control valve 36 is normally open, however, the control valves 42 and 36 for each individual injector cooler operate independently of the control valves 42 and 36 of each other injector cooler, that is, injector cooler system &#34;A&#34; operates independently of injector cooler system &#34;B&#34;. With liquid control valve 36 open, liquid refrigerant will flow from receiver 40 through pipe portion 46, through control valve 36, through pipe portion 34, through injector nozzle 20 where the venturi action of the injector nozzle 20 will draw liquid refrigerant from the surge tank 12 to mix with the liquid refrigerant flowing from the receiver 20, and into the tube side 14 of the heat exchanger 10. The liquid refrigerant flowing through the tubes 14 picks up heat from the cooled liquid flowing through the shell side of the heat exchanger 10. The refrigerant and vapors carrying latent heat of vaporization, flow from the tubes 14 into the surge tank 12. When the refrigerant and vapors enter the surge tank 12 through inlet 32, the liquid refrigerant drops down to the bottom of the surge tank while the vapor exits the surge tank 12 through inlet 32, the liquid refrigerant drops down to the bottom of the surge tank while the vapor exits the surge tank 12 through outlet pipe 28. Once the vapor from each surge tank exits outlet 28, it combines to a single suction line for the compressor 50. After the compressed vapor is discharged from the compressor, it is condensed and deposited in the common receiver 40. Since, however, the injector cooler systems are low side fixed charge systems, the heat exchanger will try to pass all of the liquid refrigerant stored in the common receiver 40 to the suction side of the compressor. However, as the liquid refrigerant level in the surge tank 12 rises, the level detector device 30 will sense a predetermined high level and cause a signal to be transmitted to liquid transfer control valve 36 and vapor transfer control valve 46, whereby liquid transfer control valve 36 closes and vapor transfer control valve 42 opens. Thus, the heat exchanger 10 will continue to operate, but now, vapor refrigerant will flow from the top of the receiver 40 through pipe portion 48, through vapor transfer control valve 42, through a vapor metering device 39, through pipe portion 38, through injector nozzle 20 which will continue to draw down liquid refrigerant from the surge tank 12, and into the shell 14 of the heat exchanger 10. The continued venturi action of the injector nozzle 20 will lower the level of refrigerant in the surge tank 12 until the level detector device 20 senses a predetermined level, at which time a signal will be transmitted to the control valves 36 and 42 and again the liquid transfer control valve 36 will open and the vapor transfer control valve 42 will close. Thereafter, the control valves 36 and 42 will continue to cycle to prevent a high liquid level in the surge tank 12 from carrying over into the suction of the compressor 50. 
     Since each injector cooler system, for example A or B, independently controls the liquid refrigerant level in its respective surge tank 12, the injector cooler systems A and B may be connected to a common refrigeration plant. 
     The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.