Abstract: Heat generated by the first stage compressor while it is running (either loaded or unloaded in the recycled purge air dryer system is recaptured by a stream of dried, cool system air drawn off of the outlet of a online drying tower in an air compressor system via a purge heat exchanger placed after the first stage compressor. The dried, hot air is used help regenerate the offline tower. This regenerating, pressurized, and heated purge air is then cooled in its passage across or through the desiccant in the regenerating tower. It then reenters the main airflow at the outlet of the first stage air compressor as wet cool pressurized purge air. This process is completely closed loop within the system, achieving zero air loss, and avoiding dew point spikes, increasing the efficiency of the air compressor system.

Abstract: Air and oil from an oil flooded screw compressor is directed through an air-oil separator. The air is cooled to extract moisture therefrom. Then the cooled air is fed to a drying tower and from the tower the air, together with hot oil from the air-oil separator, is fed to a heat exchanger which heats the air to a desired temperature for use and cools the oil to a desired temperature for re-use by the compressor. The regenerating portion of the tower communicates with the outlet of the heat exchanger for supplying dry heated air as purge air for efficient regeneration.