Gas absorption and stripping are two important separation processes used in chemical engineering to separate gas mixtures. In this process, a gas is brought into contact with a liquid, and the components of the gas mixture are either selectively absorbed or removed from the gas mixture. This process is often used to purify gas streams or to extract specific components from a gas mixture.
Gas Absorption:
Gas absorption, also known as gas scrubbing, is a process in which a gas is passed through a liquid to remove one or more of its components. In this process, the gas mixture is brought into contact with a liquid, which is typically a solvent that selectively absorbs one or more of the components in the gas mixture. The liquid is then separated from the gas, and the absorbed components are recovered from the liquid through further processing.
The gas absorption process can be carried out in various types of equipment, including packed columns, tray columns, and spray towers. Packed columns are commonly used for gas absorption because they provide a large surface area for the gas and liquid to come into contact with each other, resulting in efficient mass transfer. The solvent is fed at the top of the column and flows downward while the gas mixture is fed at the bottom and flows upward. As the gas mixture rises through the column, it comes into contact with the descending solvent, and the components of the gas mixture are selectively absorbed into the liquid. The absorbed components are then separated from the liquid, typically by distillation or evaporation.
Gas Stripping:
Gas stripping, also known as gas desorption or gas degassing, is the opposite process of gas absorption. In this process, a liquid is brought into contact with a gas mixture to remove one or more of its components. The liquid is typically a solvent, and the gas mixture is brought into contact with the liquid in a stripping column. The solvent is heated, which causes the absorbed components to vaporize and exit the liquid phase. The vaporized components are then removed from the column using a condenser and are typically condensed and collected in a separate vessel.
Gas stripping is often used in the chemical industry to remove impurities or unwanted components from a liquid stream. For example, a liquid stream containing volatile organic compounds (VOCs) can be passed through a stripping column to remove the VOCs, which can then be recovered and used as a feedstock for further processing.
Conclusion:
In summary, gas absorption and stripping are important separation processes used in the chemical industry to separate gas mixtures. Gas absorption involves the selective absorption of one or more components from a gas mixture into a liquid, while gas stripping involves the selective desorption of one or more components from a liquid into a gas. These processes are used in a wide range of applications, including air pollution control, gas purification, and the recovery of valuable components from gas or liquid streams.