Q1: In distillation columns, the number of bubble caps per tray primarily depends upon the

ANS:C - allowable gas and liquid velocities.

The number of bubble caps per tray in distillation columns primarily depends on the allowable gas and liquid velocities. Explanation:

1. Bubble Caps:
   • Bubble caps are one of the types of trays used in distillation columns for facilitating mass transfer between the vapor and liquid phases.
   • They consist of perforated plates with cylindrical or dome-shaped caps over each perforation. These caps allow vapor to pass through while promoting liquid-vapor contact and bubble formation.
   • The number of bubble caps per tray determines the efficiency of the distillation process by influencing the degree of vapor-liquid contact and mass transfer.
2. Gas and Liquid Velocities:
   • The design of the distillation column trays, including the number of bubble caps per tray, is influenced by the allowable gas and liquid velocities.
   • The gas velocity must be controlled to ensure that the bubbles formed by the vapor passing through the bubble caps have sufficient residence time in the liquid phase for efficient mass transfer to occur.
   • Similarly, the liquid velocity across the tray is also critical for proper distribution and coverage of the tray area, ensuring effective contact with the rising vapor.
   • The number of bubble caps is typically adjusted based on these velocities to optimize the balance between gas-liquid contact efficiency and hydraulic performance.
3. Feed Composition:
   • While the feed composition can influence the overall design and operation of the distillation column, including factors such as tray spacing and column diameter, it is not the primary determinant of the number of bubble caps per tray.
   • Instead, the feed composition may influence other aspects of tray design and column operation, such as the selection of column internals and the reflux ratio, to achieve the desired separation efficiency.