Internally heated regenerative air dryer is the full line industrial duty internally heated regenerative air dryer. The compressed air laded with moisture vapor enters the system through the right inlet valve and proceeds to enter the desiccant bed through the stainless steel diffuser screen. The air flows up from the bottom of the tank to the top allowing separated and condensed liquid to remain at the bottom of the vessel not contaminating the rest of the desiccant. The dehydrated compressed air then exits the right vessel through the top stainless steel diffuser screen, and past the outlet check-valve. The adsorbent purge air enters the vessel in the primary heater tube flowing down while it reaches regeneration temperature. It then enters the secondary heater tube where the purge flow returns to the top of the desiccant bed and flows down heating the desiccant bed and collecting moisture from the desiccant.