Desiccant Air Dryers
Desiccant (Adsorption) Air Dryer
Dryers that remove moisture from compressed air with a desiccant to deliver dry air with a dew point of around -40 °C. By regeneration method they divide into purge types (heatless, heater purge, blower heater purge) and non-purge types (heat of compression, blower heater). GENEQ designs and builds all five series in-house.
Drying by capturing moisture with a desiccant
A desiccant air dryer uses a desiccant such as activated alumina or molecular sieve to capture and remove moisture from compressed air.
It achieves sub-zero dew points (-40 °C standard) that a refrigerated dryer cannot reach, so it is used in processes that must prevent condensation in piping, instrument malfunctions and product defects.
Two adsorption towers alternate between adsorption (drying) → regeneration (moisture release) for continuous operation.
The heat source and air used for regeneration are what set the models apart, and what determine the operating cost.
Purge and non-purge types
Item | Purge type | Non-purge type |
|---|---|---|
Regeneration method | Uses dried compressed air for regeneration and vents it | Uses no compressed air for regeneration |
Compressed air loss | Yes (about 4–15% depending on model) | None (zero) |
Character | Energy-consuming, lower initial investment | Energy-saving, lower operating cost |
Models | SPL (heatless) · SPH (heater purge) · SPBH (blower heater purge) | SNHH (heat-of-compression heater) · SNBH (blower heater) |
The compressed air that a purge-type dryer vents is compressor power. The longer the operating hours and the larger the capacity, the greater the payback from a non-purge dryer.
Model lineup
Series | Type | Regeneration heat source / compressed air used | Best suited to |
|---|---|---|---|
SNBH | Blower heater non-purge | Ambient air (blower) + heater / 0% | The most common energy-saving type. Large capacity, long operating hours |
SNHH | Heat-of-compression heater non-purge | Compressor heat of compression (about 100 °C) + heater / 0% | Sites where heat of compression is available. Saves heater power as well |
SPBH | Blower heater purge | Ambient air (blower) + heater / about 4% | The most economical of the purge types |
SPH | Heater purge | Heater / about 8% | Simple design, stable very low dew point |
SPL | Heatless | None (pressure swing, PSA) / about 15% | Small to medium capacity, when installation and operation must be simple |
Standard design conditions
Item | Standard condition (STD) |
|---|---|
Inlet air pressure | 7 barg |
Inlet air temperature | 40℃ |
Guaranteed outlet dew point | -40℃ |
Cycle time | 8 hr/cycle (4 hr adsorption, 4 hr regeneration) · SPL: 10 min/cycle |
The standard specifications above vary with site conditions; please contact us for your capacity, dew point and pressure requirements.
Desiccant selection
The desiccant fill is chosen to match the required dew point. For a standard low dew point (-40 °C) we use activated alumina; for a very low dew point (-80 °C) we combine activated alumina with molecular sieve.
Item | Active Alumina | Molecular Sieve | Alumina Silica |
|---|---|---|---|
SIZE | 4 ~ 6 | 3 ~ 4 | 2.4 ~ 4.75 |
Al2O3 | 93% | - | 15% |
SiO2 | 0.02% | - | 85% |
Total Pore Volume | 0.5 cc/g | 0.4 cc/g | 0.45 cc/g |
Bulk Density | 769 g/l | 700 g/l | 760 g/l |
Crush Strength | 25 ~ 32 kg | 20 kg | 15 ~ 20 kg |
Surface area | 360 ㎥/g | 750 ㎥/g | 600 ㎥/g |
Packing density | 750 kg/㎥ | 780 kg/㎥ | 600 kg/㎥ |
Regeneration temperature | 180 ~ 200℃ | 200 ~ 230℃ | 140 ~ 150℃ |
Regeneration heat required | 824 kcal/kg | 850 kcal/kg | 670 kcal/kg |
Dewpoint (@ATM) | -40 ~ -60℃ | -50 ~ -80℃ | -40 ~ -80℃ |
Integrated monitoring (HMI) · PLC
Custom HMI screens that show temperatures, valve status and operating time as a P&ID flow diagram
Choice of PLC brand (Siemens, Melsec, LS and others; Siemens standard) / screen 10.4" to 15" (10.4" standard)
With a communication link to a supervisory control room, data transfer and remote control are possible (optional)
Monitoring, operation and alarms / heating temperature, dew point operation and temperature control settings / dew point, temperature and pressure trend screens
In-house design and manufacturing capability
GENEQ holds numerous patents related to desiccant dryers (balanced-load flow control, closed-loop circuit, multi-dew-point desiccant control, microwave vacuum regeneration, closed-loop moisture and CO2 removal and more). Beyond standard products, we also carry out retrofits and energy diagnostics of existing equipment.
We also design and build non-standard equipment such as CO2 removal and N2 gas dryers and combination systems that pair an indirect refrigerated dryer with a desiccant dryer.
Sales inquiries
We propose the optimal model based on your required dew point, capacity, pressure and temperature conditions, and whether heat of compression is available.
From design, manufacturing, installation and commissioning through to later maintenance and parts supply, GENEQ takes full responsibility.
