In HOC type dryer, hot air at 140 degree Celsius to 160 degree Celsius from Compressor discharge is directly used for the desiccant regeneration. Running cost of this dryer is virtually NIL. It has two drying towers filled with the Activated alumina / Molecular sieve desiccant and they alternate in process every 4-hour automatically.
Compressed air directly from air compressor discharge is taken to air dryer inlet through pipelines at 140 degree Celsius (Min) temperature. This hot air is passed one drying vessel where saturated desiccant is regenerated by this high temperature air. After picking up moisture from bed, this air is cooled in an intermediate cooler. Here moisture is condensed and removed by an auto drain trap. At 40 degree Celsius temperature this air passes through second drying vessel where moisture gets adsorbed and dry air comes out. Cycle time is (2 + 2)hours regeneration and (2 + 2)hours drying. After 4-hours changeover of vessels takes place. In the regeneration cycle heating of the bed is only for 2-hours and thereafter the bed is cooled by dry air. Dry air is cooled to 40 degree Celsius temperature before going out of the air dryer.
Due to NIL operating cost, this design is becoming more popular. To utilize full heat energy of compressor discharge, HOC type dryer should be located very close to compressor discharge. These dryers are recommended only for Dew-Point (-) 40 degree Celsius and the capacities above 500 Nm3 /hr. In smaller capacity the hot air discharge does not reach 140 degree Celsius and hence this design can’t be used.
Energy conservation by heat of Compression type compressed air dryer is a breakthrough in compressed air drying technology. The hot air from the compressor at 140 °C and higher temperature is used directly for regeneration of the desiccant. After regeneration, this air is cooled down to 40 °C and then it is dried in second tower. Thus the use of heaters is eliminated cycle the hot air is fed for regeneration for 4 hours and for balance 2 hrs. a changeover takes place where the air is first cooled in cooler, then dried and before going to the outlet, cools the regenerated desiccant bed, thus bringing it down to ambient temperature.
This cycle is reversed for next 4 hours where the adsorbed drying the air in the previous cycle goes for regeneration and vice versa. The dryer is fully automatic with pneumatically actuated Ball/plug valves. A sequence timer controls operation of these valves. There is considerable power saving in this type of Air Dryers and the dew point is also better than the refrigerated type of dryers whereas, the power consumption is almost negligible.
Salient Features
- After Filter are Provided (1W + 1S) . Sintered branss type only.
- Moisture Cum Pre filters Provided Because Of High Temperature.
- HOC Dryer is no purge loss design.
- Maintenance is easy and simple as there are no heaters and no other moving parts except 4- way valves.
- Fully automatic, continuous operation without any attention of operator.
- Negligible operating cost. It neither requires electric power for regeneration nor there do any purge loss of compressed air.
- Minimizes potential for wear and mechanical failure.
- Lower initial cost than other regenerative dryer designs.
- The design consumes none of your valuable dry air
