ANS:C - Plate

A plate column, also known as a tray column or sieve tray column, is a type of column used in chemical engineering for separation processes such as distillation, absorption, and stripping. In a plate column, the interior of the column is divided into several horizontal sections, or "plates," which are perforated to allow the passage of vapor and liquid. Each plate acts as a stage where vapor and liquid come into contact, facilitating mass transfer between the two phases. The key components of a plate column include:

1. Trays or Plates: These are horizontal sections within the column where vapor and liquid interact. The trays are typically perforated to allow vapor to pass through while retaining liquid on the surface of the tray. There are various types of trays, including sieve trays, bubble-cap trays, valve trays, and structured packing trays, each designed for specific applications and operating conditions.
2. Downcomers: These are passages located between adjacent trays that allow liquid to flow downward from one tray to the next. Downcomers help maintain a continuous flow of liquid through the column, ensuring efficient contact between the vapor and liquid phases.
3. Reboiler and Condenser: A reboiler located at the bottom of the column provides heat to vaporize the liquid feed, while a condenser located at the top of the column condenses vapor into liquid distillate. The reboiler and condenser are essential components for maintaining the distillation process.

Plate columns offer several advantages for separation processes:

• Efficient Mass Transfer: The trays provide multiple stages for vapor-liquid contact, allowing for efficient mass transfer between the two phases.
• Flexible Operation: Plate columns can be designed with different types of trays and operating conditions to achieve specific separation objectives.
• Ease of Maintenance: Plate columns are relatively easy to inspect and maintain compared to packed columns, as the trays can be accessed and replaced individually if necessary.

However, plate columns also have limitations, such as higher pressure drops compared to packed columns and potential tray fouling issues. The selection between plate and packed columns depends on factors such as the properties of the feed mixture, desired separation efficiency, and operational constraints.