Air Dryer

This is the simplest type of Air Dryer with Activated Alumina desiccant. It consists of

2-Drying Vessels which alternate every 5-minutes. Regeneration of the desiccant is by

pressure swing method in which around 7% dry compressed Air Working pressure of

60-psig minimum otherwise desiccant does not regenerate by Heatless method. In the higher pressures range these are suitable upto 70 Kg / cm²g pressure.    

Compressed air is becoming more and more costly due to high power costs. Therefore,

In smaller capacities this air purge loss is not that significant and therefore, upto

500 NM³/hr Capacitirs Heatless Dryer is preferable. Cost wise also this design is the

CHEAPEST.These are virtually maintenance free, fully automatic and require no attention for years.
Recommended for capacities from 2 NM³ / hr to 500 NM³ /hr. Minimum Air pressure should be 4 Kg /cm²g.

When lower Dew point of the order of(-) 60 to (-) 80⁰C are needed, internally Heat Reactivated Dryer is the ONLY CHOIE. It this design the regeneration of the desiccant is by little dry purge assisted by electrical heating. In each desiccant tower an electrical heater is provided in a central which heats the desiccant to around 100⁰C. Since regeneration is by dry air, even 100⁰C.regeneration temperature is quite adequate for complete regeneration. Up to Minus 60⁰C. Dew point desiccant used is Activated Alumina while Molecular sieves is used for (-)80⁰C.dew point.     

 In capacities bigger then 500 NM³/hr, this deign is more economical as compared to Heatless type as in this design purge loss of air is very small. However, in smaller capacities also this Design is preferred for lower Dew point of (-) 60 to (-) 80⁰C.  

Cost wise these dryers are around 40 % costlier then Heatless type. Operating pressure can be from 0.5 Kg/cm²g to 80 Kg /cm² a.

In all Heat Reactivated designs described above, thermal energy is required from outside for regenerating the desiccant. In HOC type Dryer there is no requirement of external heat energy. Hot air at 120 to 140⁰C. from Compressor discharge is directly used for desiccant regeneration. Running cost of this dryer is virtually NIL. It has 2-Drying towers filled with Silica Gel desiccant and alternate every 6 hours automatically. Due to large size of vessels, big quantity of desiccant, initial cost of this type Air Dryer is also high.

This is the latest design in Air Dryers and is feasible only in capacities above 300 NM3 / hr. ( in smaller capacity Air Compressor, the hot air discharge temperature of 140⁰C. is not available and hence this design cannot be used ). Due to NIL operating cost, these dryers are becoming popular. To utilize full heat energy of compressor discharge, HOC

Type dryers should be located very close to Air Compressor discharge.

These Dryers are recommended only for Dew point upto (-) 400C and for capacities above 300 NM³ /hr. Operating pressures can be from 7 Kg/ cm² to 20 Kg /hr cm² .

Use of these dryer has increased in last few year. As suggested in name it cool the air up to 3⁰C at certain pressure. So, its give 3⁰C pressure dew point and (-30 to -20)⁰C atm dew point depending upon the pressure of air. There is no air loss in this type of air dryer.

Recommended for capacities from 2 NM³ / hr to 500 NM³ /hr. Minimum Air pressure should be 4 Kg /cm²g. These air dryer are not suggested to rural remote place, where availability of technician is difficult.