Activated alumina is usually filled in the adsorption bed in spherical or approximately spherical particles. When compressed air or feed air passes through the adsorbent bed, the moisture in the air comes into contact with the activated alumina particles and is adsorbed by the pores. Particle size will directly affect the flow state of the gas in the bed and the contact process between the gas and the adsorbent.
If the particle size of activated alumina is too small, the gaps formed between the particles are usually reduced, and the resistance when gas passes through the bed may increase, thereby increasing the system pressure drop. In some equipment that is relatively sensitive to airflow resistance, this may affect the operating efficiency of the equipment.
If the particle size is too large, although the airflow resistance of the bed may be relatively low, the mass transfer distance between the gas and the particles may increase, and the effective contact process between the gas and the adsorbent per unit time may also be affected. Therefore, the particle size of activated alumina needs to find an appropriate balance between adsorption performance and airflow resistance.
What Are the Characteristics of Small-Particle-Size Activated Alumina?
Activated alumina with a smaller particle size has a larger external contact area and, under certain conditions, can shorten the mass transfer distance for moisture to enter the interior of the adsorbent. Therefore, in some adsorption conditions that require faster mass transfer, small-particle-size particles have certain advantages.
However, at the same time, small particles may also bring a greater risk of bed resistance. When a large amount of fine particles is filled into the adsorption tower, the gaps between the particles are small, and the resistance that the gas needs to overcome when passing through the bed may increase. If the equipment itself has strict requirements for pressure drop, simply choosing smaller activated alumina particles is not necessarily a reasonable solution.
In addition, if the mechanical strength of small particles is insufficient during filling, transportation, and long-term adsorption-regeneration cycles, they may also produce more wear and dust. Therefore, for air separation equipment, particle size cannot be considered separately from mechanical strength.
What Are the Advantages of Large-Particle-Size Activated Alumina?
Relatively larger activated alumina particles can usually form larger gaps between particles, which is conducive to gas passing through the adsorption bed. In some applications with large gas flow rates and where equipment needs to control pressure drop, larger particle sizes of activated alumina may be more suitable.
However, a large particle size does not mean that it necessarily has better adsorption performance. If the particle size is too large, the mass transfer distance required for moisture to enter the internal pores from the particle surface may increase. Under rapid cycling or operating conditions with high requirements for mass transfer rate, special attention needs to be paid to its dynamic adsorption performance.
How Should the Common Particle Sizes of Activated Alumina for Air Separation Equipment Be Selected?
In actual procurement, common industrial activated alumina specifications can cover different particle sizes, such as 2–3 mm, 3–5 mm, 4–6 mm, 5–7 mm, etc., and customized particle sizes can also be provided according to customer equipment requirements.
For equipment that requires a lower pressure drop, products with larger particle sizes can be mainly evaluated; for adsorption systems that pay more attention to mass transfer speed, smaller particle sizes can be further evaluated. However, the final selection still needs to be confirmed based on gas flow rate, adsorption pressure, regeneration method, bed height, and equipment design.
For air separation equipment that has already been put into operation, if the original activated alumina has stable performance, when changing suppliers, it is also not recommended to directly change the particle specification only based on price. Replacing it with a different particle size may change the bed pressure drop, filling volume, and airflow distribution. Therefore, it is better to match it according to the original adsorbent specification and the actual operating conditions of the equipment.
Zibo Xiangrun Activated Alumina for Air Separation Equipment
Zibo Xiangrun Environmental Engineering Co., Ltd. is a professional alumina manufacturer with more than 10 years of production experience, and its products are exported worldwide. For industrial air drying and air separation equipment applications, Zibo Xiangrun can provide activated alumina products suitable for different adsorption beds and equipment operating conditions, and can provide corresponding particle size specifications according to customer equipment requirements.
Zibo Xiangrun activated alumina focuses on particle uniformity, mechanical strength, low attrition, and stable adsorption performance. It can be used for air drying, air separation equipment, PSA oxygen and nitrogen production, and industrial gas pretreatment. If you have any questions or requirements regarding activated alumina, please feel free to contact Zibo Xiangrun Environmental Engineering Co., Ltd. — a professional alumina manufacturer.