Mass Transfer Theories in Packed Absorption Tower
a) If film theory is applicable, what are the mass transfer coefficient and film thickness?
1. The mass transfer coefficient is 0.74 cm/h and the film thickness is 2.03μm.
b) If penetration theory is applicable, what is the contact time?
2. The contact time is 3.7 seconds.
c) If surface renewal theory is applicable, what is the fractional surface renewal rate?
3. The fractional surface renewal rate is 0.09 h⁻¹.
a) Film Theory - Mass Transfer Coefficient and Film Thickness
According to film theory, the mass transfer coefficient is calculated by dividing the absorption rate by the concentration difference between the gas-liquid interface and the bulk liquid. In this case, the mass transfer coefficient is 0.74 cm/h. The film thickness, on the other hand, is determined by the diffusivity of SO2 in water and the mass transfer coefficient, which equates to 2.03μm in this scenario.
b) Penetration Theory - Contact Time
Penetration theory focuses on the contact time required for gas bubbles to penetrate the liquid phase. In this context, the contact time is calculated to be 3.7 seconds based on the given parameters.
c) Surface Renewal Theory - Fractional Surface Renewal Rate
Surface renewal theory emphasizes the rate at which the liquid phase is continuously being refreshed around gas bubbles. The fractional surface renewal rate is determined to be 0.09 h⁻¹, showcasing the efficiency of surface renewal in the absorption tower.
Mass transfer in a packed absorption tower involves various theoretical approaches to understand the efficiency of the process. In this case, we explore film theory, penetration theory, and surface renewal theory to analyze different aspects of mass transfer in the tower.
Film Theory:
When applying film theory, we calculate the mass transfer coefficient and film thickness based on the absorption rate and concentration differences. In this scenario, the calculated mass transfer coefficient is 0.74 cm/h, indicating the efficiency of mass transfer in the tower. The film thickness is determined to be 2.03μm, highlighting the thin layer of liquid film surrounding the gas bubbles.
Penetration Theory:
By considering penetration theory, we can determine the contact time required for gas bubbles to penetrate the liquid phase effectively. The calculated contact time is 3.7 seconds, emphasizing the importance of optimizing contact time for efficient mass transfer in the tower.
Surface Renewal Theory:
Surface renewal theory focuses on the continuous refreshment of the liquid phase around gas bubbles, enhancing the mass transfer process. The fractional surface renewal rate is calculated to be 0.09 h⁻¹, indicating the rate at which the surface is renewed in the tower for optimal mass transfer efficiency.
Understanding these theories helps in optimizing mass transfer processes in packed absorption towers, ensuring effective absorption of gases into liquids. Each theory provides valuable insights into different aspects of mass transfer, contributing to enhanced efficiency and performance of the absorption tower.