Q1: For gas absorption, low viscosity solvents are preferred, because of their

ANS:D - all (a), (b) and (c).

Better flow characteristics:

1. • Low viscosity solvents offer improved flow characteristics compared to high viscosity solvents. Viscosity refers to the resistance of a fluid to flow.
   • With low viscosity solvents, the resistance to flow is reduced, resulting in smoother and more uniform flow patterns within the absorption system.
   • This enhanced flow promotes better mixing and distribution of the solvent within the system, ensuring more efficient contact between the gas and liquid phases.
   • As a result, low viscosity solvents facilitate more effective mass transfer between the gas and liquid phases, leading to improved absorption efficiency.
2. Low pumping pressure drop:
   • When a solvent is pumped through the absorption system, it experiences resistance to flow due to frictional forces acting on it.
   • Low viscosity solvents have lower resistance to flow, meaning they experience less frictional resistance as they are pumped through pipes, valves, and other components of the absorption system.
   • As a result, low viscosity solvents require less energy to overcome pumping resistance, leading to lower pumping pressure drop.
   • Lower pumping pressure drop translates to reduced energy consumption, lower operating costs, and less wear and tear on pumping equipment.
3. Rapid absorption rates:
   • In gas absorption processes, the rate at which gas molecules are absorbed into the liquid phase depends on the mass transfer rate between the two phases.
   • Low viscosity solvents allow gas molecules to diffuse more rapidly into the liquid phase due to their reduced resistance to mass transfer.
   • The faster diffusion of gas molecules into the liquid phase results in more rapid absorption rates when low viscosity solvents are used.
   • This means that low viscosity solvents can achieve higher rates of gas absorption per unit time compared to high viscosity solvents, leading to quicker removal of gases from the gas phase.

In summary, low viscosity solvents offer better flow characteristics, low pumping pressure drop, and rapid absorption rates in gas absorption processes. These attributes contribute to more efficient and cost-effective operation of absorption systems, making low viscosity solvents preferred choices for many absorption applications.