Question

Which one of the given statements is correct with reference to gas-liquid contactors for mass transfer applications?

• A. A tray tower is more suitable for foaming systems than a packed tower.
• B. Tray towers are preferred over packed towers for systems requiring frequent cleaning.
• C. For a given liquid flow rate, the gas flow rate in the loading region is greater than that in the flooding region.
• D. Flooding can never occur for counter-current contact.

Hint:

For gas-liquid contactors, consider factors like cleaning requirements, fouling tendencies, and operational limits (e.g., flooding) when selecting between tray and packed towers.

Answer 1

The Correct Option is B

Step 1: Analyze the suitability of tray towers and packed towers.
- Tray towers are generally easier to clean compared to packed towers due to their open design and accessibility. This makes them preferable for systems requiring frequent cleaning, such as those handling viscous or fouling liquids.
- Packed towers, on the other hand, are more prone to fouling, and cleaning them is more challenging due to the packing materials.
Step 2: Evaluate the other options.
1. A tray tower is more suitable for foaming systems than a packed tower. This is incorrect. Packed towers are generally better for handling foaming systems as they minimize foam generation due to the low liquid holdup compared to tray towers.
2. For a given liquid flow rate, the gas flow rate in the loading region is greater than that in the flooding region.
This is incorrect. The gas flow rate in the flooding region exceeds that in the loading region, as flooding occurs at higher gas velocities.
3. Flooding can never occur for counter-current contact. This is incorrect. Flooding can occur in counter-current gas-liquid contactors when the gas flow rate is too high, causing liquid to back up or be entrained.
Step 3: Conclusion: The correct statement is that tray towers are preferred over packed towers for systems requiring frequent cleaning.