In a cross current-flow scrubber, what happens to gas velocity and efficiency when the cross-sectional area increases?

In a cross current-flow scrubber, what happens to gas velocity and efficiency when the cross-sectional area increases?

• A. Gas velocity decreases, efficiency increases
• B. Gas velocity increases, efficiency decreases
• C. Gas velocity decreases, efficiency decreases
• D. Gas velocity increases, efficiency increases

Answer: (C)

In a cross current-flow scrubber, gas velocity is set by the volumetric gas flow rate divided by the cross-sectional area. So when you increase the cross-sectional area while keeping the flow rate the same, the superficial gas velocity decreases. The removal efficiency in a cross-flow scrubber depends on how well the gas and liquid phases contact each other and transfer contaminants; slower gas flow reduces the interaction and mass-transfer opportunities between gas and liquid, leading to a lower removal efficiency. Therefore, increasing cross-sectional area tends to reduce both gas velocity and efficiency.

In a cross current-flow scrubber, gas velocity is set by the volumetric gas flow rate divided by the cross-sectional area. So when you increase the cross-sectional area while keeping the flow rate the same, the superficial gas velocity decreases. The removal efficiency in a cross-flow scrubber depends on how well the gas and liquid phases contact each other and transfer contaminants; slower gas flow reduces the interaction and mass-transfer opportunities between gas and liquid, leading to a lower removal efficiency. Therefore, increasing cross-sectional area tends to reduce both gas velocity and efficiency.