Specific application of activated alumina in air dryer
Time:2025-03-07
In industrial compressed air systems, residual moisture can cause equipment corrosion, valve jamming, spray defects, and other issues. Activated alumina, as an efficient desiccant, has become a core material in the field of compressed air dryer due to its unique physical and chemical properties. This article deeply analyzes the core value of activated alumina in air compressor systems from technical principles to practical applications.
1. Core characteristics and advantages of activated alumina
- High specific surface area: 300-340m2 /g, providing dense adsorption sites.
- Multi level pore structure: dominated by micropores (2-5nm), with consideration given to mesopores (5-50nm), suitable for rapid diffusion of water molecules (0.28nm).
- Surface characteristics: Polar adsorption ability, strong affinity for water molecules.
- Crush strength: 3-5mm ≥ 150N/particle (ASTM standard), reducing powdering loss.
2. Application principle in compressed air drying system
1#. Working process of adsorption dryer
1) Compressed air enters: Wet and hot air (dew point 40 ℃~80 ℃) passes through a pre filter.
2) Twin tower adsorption:
- Tower A adsorption: Air passes through the activated alumina bed, water molecules are adsorbed, and the dew point drops to -40 ℃ to -70 ℃.
- Tower B regeneration: 5-15% dry air is heated in reverse (180-220 ℃) to desorb moisture and discharge.
3) Cycle switching: Switch the adsorption/regeneration tower every 4-10 minutes to achieve continuous drying.
2#. Adsorption efficiency of activated alumina
- Adsorption rate: Under a pressure of 0.7MPa, the diffusion coefficient of water molecules reaches 5 × 10 ⁻⁶ cm ²/s, and 90% adsorption is completed within 30 seconds.
- Penetration curve: When the dew point of the bed outlet air rises by 3 ℃, adsorption saturation is determined (typical penetration time 4-8 hours).
- Regeneration efficiency: Hot blowing at 180 ℃ for 4 hours, regeneration rate>95%, residual water content<1.5wt%.
3. Application condition and technical parameters
1#. General industrial compressed air drying
- Operating requirements: Dew point -40 ℃, processing capacity 10-100Nm ³/min, pressure 0.7-1.0MPa.
- The loading plan is as follows:
* Double layer bed design: The bottom layer of activated alumina (common 3-5mm and 4-6mm) adsorbs moisture and protects the upper layer of molecular sieve (such as 4A molecular sieve) particles from damage, thereby achieving deep drying.
* Single tower loading capacity: 25-30kg of activated alumina needs to be loaded for every 1Nm ³/min of air processed.
2#. Electronic manufacturing industry
- Requirement: To prevent oxidation of the circuit board, with a dew point below -70 ℃.
- Composite solution: Pre activated alumina adsorption (dew point -40 ℃) → post molecular sieve deep drying (dew point -70 ℃).
In industrial compressed air systems, residual moisture can cause equipment corrosion, valve jamming, spray defects, and other issues. Activated alumina, as an efficient desiccant, has become a core material in the field of compressed air dryer due to its unique physical and chemical properties. This article deeply analyzes the core value of activated alumina in air compressor systems from technical principles to practical applications.
1. Core characteristics and advantages of activated alumina
- High specific surface area: 300-340m2 /g, providing dense adsorption sites.
- Multi level pore structure: dominated by micropores (2-5nm), with consideration given to mesopores (5-50nm), suitable for rapid diffusion of water molecules (0.28nm).
- Surface characteristics: Polar adsorption ability, strong affinity for water molecules.
- Crush strength: 3-5mm ≥ 150N/particle (ASTM standard), reducing powdering loss.
2. Application principle in compressed air drying system
1#. Working process of adsorption dryer
1) Compressed air enters: Wet and hot air (dew point 40 ℃~80 ℃) passes through a pre filter.
2) Twin tower adsorption:
- Tower A adsorption: Air passes through the activated alumina bed, water molecules are adsorbed, and the dew point drops to -40 ℃ to -70 ℃.
- Tower B regeneration: 5-15% dry air is heated in reverse (180-220 ℃) to desorb moisture and discharge.
3) Cycle switching: Switch the adsorption/regeneration tower every 4-10 minutes to achieve continuous drying.
2#. Adsorption efficiency of activated alumina
- Adsorption rate: Under a pressure of 0.7MPa, the diffusion coefficient of water molecules reaches 5 × 10 ⁻⁶ cm ²/s, and 90% adsorption is completed within 30 seconds.
- Penetration curve: When the dew point of the bed outlet air rises by 3 ℃, adsorption saturation is determined (typical penetration time 4-8 hours).
- Regeneration efficiency: Hot blowing at 180 ℃ for 4 hours, regeneration rate>95%, residual water content<1.5wt%.
3. Application condition and technical parameters
1#. General industrial compressed air drying
- Operating requirements: Dew point -40 ℃, processing capacity 10-100Nm ³/min, pressure 0.7-1.0MPa.
- The loading plan is as follows:
* Double layer bed design: The bottom layer of activated alumina (common 3-5mm and 4-6mm) adsorbs moisture and protects the upper layer of molecular sieve (such as 4A molecular sieve) particles from damage, thereby achieving deep drying.
* Single tower loading capacity: 25-30kg of activated alumina needs to be loaded for every 1Nm ³/min of air processed.
2#. Electronic manufacturing industry
- Requirement: To prevent oxidation of the circuit board, with a dew point below -70 ℃.
- Composite solution: Pre activated alumina adsorption (dew point -40 ℃) → post molecular sieve deep drying (dew point -70 ℃).
