Air compression involves making the molecules come closer, and thus force them to fit into a smaller space. This process involves an increase in temperature and is known as the heat of compression. In any air compressor or compression air dryer, this same process is involved and thus results in a lot of heat emission. It is dangerous to leave the heat emitted unattended because it can easily overheat the compressor and can result in an explosion.
Activated alumina balls as the drying medium in a heatless compression air dryer is the best choice to avoid this overheating of the compressor. Let’s look at the heatless compressed air dryer.
Heatless compressed Air dryer
By using activated alumina for the air dryers, we can devise the heatless compressed air desiccant dryer. A dual-chambered arrangement filled with desiccants is aligned to adsorb the water molecules from compressed air. The final output would be hot dry air. The heat of adsorption is retained by the desiccant balls and is prevented from being accumulated at the chamber outlet. This heat is further used for regeneration in the subsequent cycle to nullify the heat accumulation. Effective heat retention, a dense medium of high volumetric heat capacity can be introduced at the end of the adsorption chamber.
But this process consumes a portion of the dry air output from a compressed air dryer. The amount of this consumption can be reduced by the below methods:
There are majorly two types of desiccant air dryers which are pressure swing compressed air dryers and externally heated compressed air dryers. The pressure swing regenerative dryers and the high-pressure swing dryers are efficient in reducing the accumulated heat from the entire system. These regenerative dryers make use of the adsorption heat energy retention concept to maintain the heat of compression within limits.
Air drying desiccant balls
The best air dryer desiccant beads in use are activated alumina. It is very important to keep compressed air free of moisture because moist compressed air can cause various damages to the compressor. The valves, motors, and insulations can be affected, the final product can be altered, rusting and corrosion, damage to pipes, total blockage of the system are some examples of the adverse effects of moisture content in the compressed air. So, it is very important to maintain the PDP of a compressor system as low as -40 degrees centigrade.
Regeneration dryers that involve activated alumina balls as adsorbents have doubtlessly proven to be highly efficient and effective. Activated alumina uses the concept of adsorption to trap water molecules that come in contact with the desiccant surface. With no chemical or thermal reactions involved, the use of desiccant air dryer beads is of low operating and maintenance cost. Activated alumina balls are non-toxic, colorless, tasteless, and insoluble, and have high thermal and mechanical strength.
The ease of regeneration of activated alumina balls is a highly recommendable feature. Activated alumina balls in the desorption chamber of the dryer are triggered to action as they saturate with the moisture content from the compressed air. It does not require any additional systems involved and in the context of heatless air compressor dryers, this regeneration phase helps to reduce the heat retained during the adsorption.
Sorbead India is one of the leading manufacturer of activated alumina balls over the years. The quality of desiccant balls, a wide range of quantities available, and easy access to products has helped us remain your trusted partner in all kinds of desiccant requirements. Our heatless compressor air dryer desiccant balls have proven to be highly efficient.
Activated alumina is one of the high performing desiccants among its counterparts. It is used for the purification of various liquids and gases. Been available in various grade, activated alumina balls have a huge surface area that can go above 200 sqm/gm.
AD101 is the finest grade of activated alumina balls as it has a surface area of around 415sqm/gm. It is made of aluminium oxide and ranges from 1 - 3 mm (2mm), 2 - 5 mm (3.2mm), 5 - 8 mm (6.2mm), etc.
Activated alumina balls specifications and parameters (AD101) are as below:
Bulk density (Kg / m3 )
BET Surface area (m2 / gm)
Pore Volume (cc / gm)
Adsorption Capacity (60% RH)
Attrition Loss (%)
Application of AD101 grade alumina balls
Being an excellent performing adsorbent, AD101 grade alumina finds its application in compressed air dryers, air separation plants and heatless air dryers. One of the major applications is the fluoride removal by activated alumina. Fluoride levels in water if crosses a level can prove dangerous and lead to fluorosis.
By letting water through these powerful desiccants, the fluoride content from water is adsorbed that reducing the levels from 5ppm to less than 1ppm.
Other applications of AD101 grade alumina balls are removal of HCL from contaminated gas flow, Catalyst Bed Support, and Drying of Feed air to N2 – O2 Cryogenic plan,
Sorbead India is one of the prime activated alumina suppliers and manufacturers who deliver high-quality products to their clients across the globe. Contact for more details
If you wonder the connection between dew point and activated alumina then here, we are explaining the same to you. But before we get into more details let us define dew point first.
What is the dew point?
Dew point is the temperature below which water droplets start to condense and form dew. To reach dew point the air is cooled. This condensation process happens in stages. Once the air is cooled at first it becomes saturated with water vapors, next it forms liquid water and finally upon reaching dew points, the water vapor condenses and forms dew. Dew point measures the atmospheric moisture. Greater the dew point greater will be the moisture content in the atmosphere.
Use of activated alumina ball for better dew point
Activated alumina is used for various industrial applications to remove moisture content or impurities. With excellent surface area, perfect mechanical strength, great resistance to thermal shocks, activated alumina is used in multiple applications. Be it activated alumina for gas drying, activated alumina for fluoride removal or activated alumina for water treatment, all of these procedures require a dew point to be reached -40 ° C.
Conditions such as compressed air dryers where the reaching of dew point is quite an affair, activated alumina can be used. Most of the manufacturers design their activated alumina to give a dew point of -40 ° C (to the minimum) but under certain conditions such high pressure-activated alumina can be used to giver a dew point of -70 ° C.
Make proper use of activated alumina for better dew points. Only buy high-quality and good grade ones and never overuse the activated alumina.
Activated alumina has the highest water adsorption capacity when compared to its other counterpart. This desiccant is used in numerous applications.
Let’s see below the use of activated alumina balls in three applications namely:
Application of activated alumina in heatless air dryers
Heatless air dryers are one of the effective gas or air dryers that work on the principle absorption. A dew point of -40 °C is required for these dryers. Activated alumina balls used in these dryers help in the prevention of channeling of compressed air flow thus keeping the bed velocities at lower levels.
These regenerative heatless air dryers are mostly operated in two separate towered chambers. Both the towers are filled with activated alumina balls for the simultaneous air drying and regeneration process. Now let us understand the operation below:
The inlet air is directed from a pre-filter, wherein the dust particles and other impurities are removed, into an oil removing filter. Once the inlet air is freed from any impurities it is redirected into the first chamber which consists of the air dryer desiccant beads, the activated alumina balls. Thus, the air now travels through the desiccant bed leaving the moisture to be adsorbed by the activation alumina balls. The moisture-free air is then directed for the end-user.
Now the operation of chambers is reversed (by reversing the control valves) and the saturated alumina balls in the first chamber are regenerated while the compressed air dries in the second chamber. Both the process takes place simultaneously. The regeneration of saturated alumina balls is done by purging dry air or gas at atmospheric pressure and temperature in reverse direction.
Application of activated alumina in heat reactivated air dyers
Heat reactivated air dryers use desiccants such as activated alumina balls to generate compressed air and gasses at a very low dew point. When compared to heatless air dryers, the purge loss is less in heat reactivated air dryers and is best suitable for dew points lower than -60 °C to -80°C.
The operation part involves two carbon steel pressure vessels which are packed with the desiccant air dryer beads(activated alumina balls). The inlet air is directed into a pre-filter that removes any dust particles present in the air. This air is then passed into the 1st chamber with activated alumina that adsorbs the moisture content present. This drying process can go up to 4 hours and once the desiccant bed is saturated, the tower beds are reversed. Here, the compressed air drying and regeneration process happens simultaneously. Now the tower with the saturated alumina balls is put to regeneration by purging hot air generated from the electric heaters for 2 hours. By this time the temperature of the alumina balls reaches above 100°C which causes the moisture to leave them thus leading to a complete regeneration process.
Application of activated alumina in HOC dryers
IN HOC (Heat of compression) type air dryers, the compressed air/gas is generated based on the principle of adsorption. Here too, activated alumina is the air dryer desiccant used. Just as the other two air dryers(Heatless and heat-reactivated), the operation of HOC dryers also involves two chambers filled with activated alumina balls. The air drying and regeneration process happens simultaneously in these vessels and are automatically interchanged after every 4 hours. The main advantage of HOC type air dryer is that the operational cost is minimized by eliminating the need for electrical heaters.
The hot air from the compressor is used for the regeneration process of saturated alumina balls. With a minimum temperature of 130°C, this hot air discharged from the compressor is directed to pass through the saturated desiccant, from where it absorbs the moisture content. This air is then cooled and condensed at 40 °C and made to pass through the other drying vessel. The dried air cools the desiccant bed to an optimum temperature. The whole process involves 4 + 4 hours of drying and regeneration process. For being economical, HOC type air dryers are gaining huge popularity.
Activated alumina is a powerful all-purpose desiccant that is highly porous and used in multiple industrial applications. It has a high-surface-area and is highly-porous thus having greater adsorption capacity. Being an effective desiccant, activated alumina is used for air-drying units as well. In this article, we will study how activated alumina works for air drying.
Activated alumina balls are used for heated air drying, compressed air drying, van air drying and several other applications that require air drying process for obtaining the efficient end product.
Activated alumina balls will effortlessly achieve the dew point -40°F to -100°F which is required for compressed air and gas drying application. The desiccant air dryer beads (activated alumina balls) are filled in two identical towers of the air dryer unit. Among these two towers, one is used for air-drying and another one for regeneration. The functions of both the towers are interchanged or switched and are controlled by the central unit.
The compressed air is dried in the drying tower by the activated alumina balls. The second the tower which is wet and saturated undergoes regeneration by either a purge of hot air or by dried compressor air.
How is activated alumina the best desiccant for air drying?
With improved and high adsorption capacity, activated alumina desiccants work immaculately for water, moisture and pollutant adsorption from the air. Following are the features that make activated alumina the best desiccant for air drying:
Activated alumina for gas drying is another important application of this powerful desiccant. It is used for drying gasses such as Acetylene, Air, Ammonia, Argon, CO2, Cl2, Cracked Gas, Ethane, Ethylene, Freon, Furnace Gas, He, H2, HCL, H2S, CH4, N2, O2, Propane, Propylene, SO2, etc.
Activated alumina balls are a highly porous form of aluminum oxide that is known for its high adsorption capacity. This desiccant is popularly used for removal or purification of gasses, air, and liquid. Activated alumina balls have the capability of removing moisture/humidity in the fastest way possible. In this article, we will see how activated alumina balls can be used for removing moisture in ways fields of the industry.
Activate alumina balls for fluoride removal
The increased fluoride content in the water can cause a serious threat to mankind. An effective, affordable and safe way of securing this toxicity level to a safe value is by the employment of activated alumina balls. A bed of activated alumina balls is prepared and the water under treatment is made to pass through it. Due to its high surface area and high adsorption capacity, the activated alumina balls hold to be effective for the defluoridation of drinking water. The forte of the activated alumina fluoride removal process is that it adsorbs the fluoride content rather than filtering and effectively lowers the levels from 10ppm to 1ppm.
Activated alumina for water treatment
Arsenic is one of the dangerous contaminants of water. Being resistant to liquid water, this desiccant does not shrink, swell or get diluted when immersed in water for a long time. Thus, making it a perfect choice for water purification. The water to be treated is allowed to pass through a bed of activated alumina under high pressure. For improved results, more than one filter bed can be used back to back. The arsenic content gets adsorbed by activated alumina beds when passed continuously for a pre-determined time, and the processed water is collected for further use.
Due to higher surface area and maximum affinity towards water, activated alumina is one of the best air/gasses drying desiccants. The presence of humidity can contaminate the air/gasses by the ice formation or catalyst contamination. This condition can be avoided by passing the air/gas through the activated alumina balls. This cost-effective desiccant is mainly used in the industry to dry compressed air or gasses with relatively high moisture content.
Activated alumina for oil purification
Activated alumina has been used for the reconditioning of oils used in the turbine, transformer, and circuit breaker. Being resistant to shocks and abrasion, activated alumina balls are known to be highly effective in oil filtration. Oils change their characteristics with time. Acid is one of the by-products that oils generate as they deteriorate/oxidize after being in contact with moisture, air, heat, gases, etc. This if left unchecked can raise the total acid numbers causing serious damage to the mechanical parts. To avoid this, activation alumina balls can be employed in purification or removal of acids from oil. Here the number of alumina balls used depends on the total mass of oil.
Once the activated alumina balls get saturated with moisture, it becomes vital to regenerate it before further use. To remove moisture from activated alumina balls, a heatless or heated compressed air dryer is used. The hot air from the dryer is made to pass through these balls thus causing the removal of water vapors from the pores of the desiccant. Another way to regenerate saturated alumina balls is by the use of by a solution of sodium hydroxide (NaOH), hydrochloric acid (HCL), sulfuric acid (H2SO4), and alum (KAL(SO4).