Condensate harvester with liquid level sensing and control for air compressor system including a refrigerated dryer

Abstract

An air compressor system useful for supplying a stream of compressed air for an end user is disclosed which includes a refrigerated dryer useful to remove moisture and harvest it from the compressed air. The refrigerated dryer includes an evaporator and a condenser, where the evaporator is useful to produce the moisture from the compressed air. The air compressor system includes an expansion tank which collects the harvested moisture from the evaporator. The expansion tank can include a low liquid level sensor and a high liquid level sensor useful to determine level of condensate in the expansion tank. The low liquid level sensor can produce a useful to permit ingress of water from a utility water supply into the expansion tank, and the high liquid level sensor can produce a signal useful to venting excess liquid from the tank.

What is claimed is: 
     
         1 . An apparatus comprising:
 a gas compressor having an output flow of compressed air in thermal communication with an evaporator of a refrigerated dryer, the evaporator structured to cool the compressed air and thereby produce a condensate formed from water vapor in the compressed air, the refrigerated dryer also including a refrigeration pump for pressurizing a refrigeration fluid, a condenser configured to receive refrigeration fluid from the refrigeration pump, an expansion tank structured to receive the condensate produced by the evaporator during operation of the refrigerated dryer, and a condensate pump in fluid communication with the expansion tank and configured to provide condensate from the expansion tank to the condenser, the expansion tank also connected to a utility water supply via a valve and water conduit, the valve actuated by a sensor of the expansion tank that detects a low water level within the expansion tank.   
     
     
         2 . The apparatus of  claim 1 , wherein the valve includes a movable member that is energized to move as a result of a change in signal from the sensor. 
     
     
         3 . The apparatus of  claim 2 , wherein the moveable member is a solenoid that is energized to open the valve when the sensor detects the low water level. 
     
     
         4 . The apparatus of  claim 2 , which further includes a timer structured to keep the valve open for a pre-determined period of time after the sensor detects the low water level to ensure a quantity of water is delivered from the utility water supply to the expansion tank. 
     
     
         5 . The apparatus of  claim 4 , wherein the refrigerated dryer further includes a controller configured to receive input including a signal from the sensor and a high water signal from a high water sensor, and configured to provide an output excitation signal to the valve, the controller structured to override the timer and close the valve if water reaches the high water sensor prior to expiration of the pre-determined period of time. 
     
     
         6 . The apparatus of  claim 1 , wherein the expansion tank further includes a high water level sensor structured to detect a high water level in the expansion tank. 
     
     
         7 . The apparatus of  claim 6 , which further includes a temperature sensor to detect temperature of a refrigeration fluid associated with an outlet of the condenser, and a controller which is structured to: fill the expansion tank in case of low water level, and regulate the condensate pump according to a signal provided from the temperature sensor. 
     
     
         8 . An apparatus comprising:
 a compressor system including a refrigerated dryer in flow communication with a compressor and structured to remove water vapor from a compressed flow stream of the compressor, the refrigerated dryer including:   a first pump structured to convey a refrigeration cycle fluid;   a condenser for receiving the refrigeration cycle fluid from the pump and cooling the refrigeration fluid;   an evaporator in refrigeration cycle fluid communication with the condenser and in thermal communication with the compressed flow stream of the compressor;   an expansion tank structured to receive condensate formed from the water vapor by the evaporator as a result of operation of the refrigerated dryer, the expansion tank having a sensor to detect a low fluid level, a first conduit for delivering condensate to the expansion tank from the evaporator, and a second conduit for delivering water from a utility water source;   a valve structured to open the second conduit and permit water from the utility water source to enter the expansion tank when the sensor detects a low fluid level in the expansion tank; and   a second pump in fluid communication with the expansion tank and structured to provide water from within the expansion tank to the condenser.   
     
     
         9 . The apparatus of  claim 8 , which further includes an overflow valve and an overflow sensor, the overflow sensor structured to detect a high fluid level in the expansion tank 
     
     
         10 . The apparatus of  claim 9 , wherein the compressor system includes a timer used to command valve open for a pre-determined period of time. 
     
     
         12 . The apparatus of  claim 10 , wherein the valve is commanded closed by the compressor system to halt the flow of water from the utility water supply if a level of water within the expansion tank reaches the overflow sensor before expiration of the pre-determined period of time. 
     
     
         13 . The apparatus of  claim 9 , wherein the valve remains open until water reaches the overflow sensor. 
     
     
         14 . The apparatus of  claim 9 , which further includes a temperature sensor at an outlet of the condenser, wherein the pump is regulated to provide water to the condenser from the expansion tank in response to a temperature signal from the temperature sensor. 
     
     
         15 . The apparatus of  claim 14 , wherein the compressor system is structured to keep the valve open for a pre-determined period of time. 
     
     
         16 . A method comprising:
 operating a gas compressor system having a refrigerated dryer structured to dry a compressed gas stream from the compressor system;   harvesting condensate from the compressed gas stream by operation of an evaporator of the refrigerated dryer;   filling an expansion tank from condensate harvested from the evaporator;   providing condensate from the expansion tank to a condenser of the refrigerated dryer through use of a pump;   detecting a low condensate level in the expansion tank; and   supplementing the expansion tank with water from a utility water source upon the detecting a low condensate level.   
     
     
         17 . The method of  claim 16 , which further includes detecting a high water level in the expansion tank. 
     
     
         18 . The method of  claim 17 , which further includes closing a valve to halt water contribution from the utility water source upon the detecting a high water level. 
     
     
         19 . The method of  claim 18 , which further includes limiting the filling to a pre-determined time such that a valve associated with a conduit of the water supply line remains open only during the pre-determined time. 
     
     
         20 . The method of  claim 19 , which further includes sensing a temperature of refrigeration fluid in proximity to an outlet of the condenser. 
     
     
         21 . The method of  claim 20 , which further includes regulating the pump based upon the sensing a temperature of the refrigeration fluid.