1. Is a Desiccant Air Dryer Necessary?

No Need (Refrigerated Air Dryer Is Sufficient)

• Required pressure dew point: 2 ~ 10 °C

Must Be Equipped with a Desiccant Air Dryer

1. Scenarios with strict air quality requirements: precision spraying, electronics & semiconductor industry, food & pharmaceutical production, lithium battery manufacturing, precision instruments and meters.
   • Required pressure dew point: -20 °C ~ -70 °C
2. Outdoor pipelines in cold northern regions or pipelines operating below 0 °C (to prevent icing).
   • Required pressure dew point: ≤ -40 °C
3. Long-distance compressed air transmission without thermal insulation (to avoid condensed water and pipeline corrosion).

Summary

2. Step-by-Step Selection Guide for Desiccant Air Dryers

2.1 Determine Pressure Dew Point (Select by Industry Requirements)

• ●-20 °C: General industrial applications & ordinary spraying → Choose heatless regenerative type.
• ●-40 °C: Automotive spraying & food packaging → Choose heated purge regenerative type (best cost-performance).
• ●-60 ~ -70 °C: Electronics, semiconductors, pharmaceutical sterile production & lithium battery industry → Choose heated purge / blower purge type with molecular sieve.

2.2 Match Air Flow Rate (Critical, Reserve Sufficient Capacity Margin)

• ●Formula: Rated flow of desiccant dryer = Compressor free air delivery × (1.2 ~ 1.5)
• ●Example: A screw compressor with an exhaust flow of 10 m³/min shall be matched with a desiccant dryer of 12 ~ 15 m³/min.
• ●For inlet air temperature above 45 °C or altitude over 1000 m: Adjust the multiplier to 1.3 ~ 1.5.
• ●For multiple compressors operating in parallel: Adopt one centralized large-capacity dryer for higher energy efficiency and easier maintenance instead of several small units.

2.3 Select Regeneration Mode (Based on Flow Rate & Energy Budget)

Heatless Regenerative Type (Flow rate ≤ 10 m³/min)

• ●Advantages: Simple structure, low procurement cost, no electric heating power consumption.
• ●Disadvantages: High purge air consumption (15% ~ 20% of total air flow for regeneration).

Heated Purge Regenerative Type (Flow rate: 10 ~ 50 m³/min, Recommended)

• ●Advantages: Low purge air consumption (5% ~ 8%), stable dew point, excellent overall cost-performance.
• ●Disadvantages: Requires a small amount of electric heating power.

Blower Purge / Compression Heat Regenerative Type (Flow rate ≥ 50 m³/min)

• ●Advantages: Nearly no purge air consumption; compression heat type reuses waste heat from air compressors.
• ●Disadvantages: Higher price and larger footprint.

2.4 Adapt to Inlet Operating Conditions (Prevent Malfunction)

• Inlet pressure: Standard range 0.7 ~ 1.0 MPa. Select special low-pressure models for pressure below 0.6 MPa, and customized high-pressure models for pressure above 1.3 MPa.
• Inlet air temperature: Standard requirement ≤ 45 °C. Install a pre-cooler if temperature exceeds 45 °C. The adsorption capacity will drop by about 15% for every 5 °C temperature rise.
• Inlet air oil content: Must be ≤ 0.1 ppm. Oil contamination will cause permanent failure of desiccants. A three-stage filter system (dust removal, oil removal, water removal) must be installed at the front end.

2.5 Select Desiccant Media (Matched with Dew Point)

• Activated Alumina: Suitable for dew point -20 ~ -40 °C. Features good wear resistance and economical cost, for general applications.
• Molecular Sieve: Suitable for dew point -60 ~ -70 °C. Superior water adsorption capacity and high precision, for high-precision working conditions.
• Silica Gel: Rarely used in industrial dryers; vulnerable to water impact, only for low-load operation.

3. Comparison: Refrigerated Air Dryer vs Desiccant Air Dryer