When the exhaust air connects with a medium where the contaminant dissolves more successfully than in the air, the contaminant passes into the medium, releasing the purified air from the system. This phenomenon is known as the sorptive process.
Sorptive processes comprise two parts, i.e., Absorption and Adsorption. These two processes differ significantly in the way that they operate.
The two kinds of sorptive processes are mentioned below in detail:
- Absorption Process
In Absorption, a substance dissolves another substance. The contaminant or pollutant here is usually a gas, while the absorbing medium is often a liquid but can also be a solid.
Gas scrubbing is widely applied. In this process, the by-products of combustion or non-essential exhaust gas pollutants like halogens and their acids and chemicals, such as ammonia and sulphur oxides, are eliminated from exhaust gases or exhaust air. This phase works on the oxidation process and many times precedes it. Dürr Air Pollution Control System Maintenance Services in India provides a wide array of acid gas removal technologies comprising wet acid gas absorbers, dry sorbent injection, wet scrubbers, and spray dryer absorbers.
Absorption separates pollutants from the exhaust air and is used for cleaning flue gases.
- Adsorption process
The adsorption process helps in the concentration of pollutants. It’s required when the exhaust air comprises a low to medium pollutant concentration. The pollutants here form a physical connection with the adsorbent. As a result, they are drawn out of the air and directed into the adsorbent. Activated carbons and zeolite materials are the most utilized adsorbents.
When the contaminants have been concentrated, they are moved to thermal or catalytic oxidation. At this location, concentrated pollutants are eliminated. After this, the purified air is released from the system. This procedure is an affordable and productive process for cleaning exhaust air with a low concentration of contaminants. If materials recycling is needed, systems like solvent recovery and condensation are used after the adsorption process.
The adsorbents are regenerated after a certain period to ensure pollutants do not become saturated and become unable to take in any more material. This process is known as desorption. It makes use of steam, inert gas, or hot air.
There are two kinds of adsorption processes available. The first process is fixed-bed adsorption, where many adsorbers are utilized alternately in desorption and adsorption modes. The second adsorption process is done with a substantially rotating rotor system comprising a particularly designed concentration rotor.
Sorpt.X SW
Dürr Air Pollution Control System provides certified solutions for emission control using both adsorption and absorption technologies.
Adsorption is used for concentrating the pollutants. The pollutants are separated from the exhaust air after adsorption by a sorptive system. In Absorption, contaminants are removed from the exhaust air. This process is usually used for purifying flue gases.
In India, Dürr Air Pollution Control System Maintenance Services India provides many Sorpt.X SW wet scrubbers, including packed tower designs, tray towers, and spray towers for industrial acid gas emission control.
Benefits of Sorpt.X SW
- Minimal pressure drop
- Easier operation and construction
- Not susceptible to plugging
- The removal efficiency is high for a range of acid gases such as HF, SOx (SO2 and SO3), and HCl.
- The cost for capital equipment and installation is less
- Footprint is small
- Flexibility of functioning (acid gas concentration, gas volume etc.)
Functionality of Sorpt.X SW
Following the principle of acid gas removal, the acid gas is exposed to an alkaline agent, and by chemical reaction, it creates a stable salt. It can be subsequently removed with the liquid. This result is achieved in a spray chamber, like a vertical tower, where water incorporating the reagent supplies a contact surface for the chemical reaction to occur.
The reagents used often include:
- Sodium carbonate (soda ash) Na2CO3
- Sodium hydroxide (caustic) NaOH
- Calcium hydroxide (hydrated lime) Ca(OH)2
- Magnesium hydroxide Mg(OH)2