Packed Column Vs Tray Column

Packed column Vs Tray column

Selection of a plate column or packed column can be done on the following basis :

Plate columns

1. Plate columns can handle a wide range of gas and liquid flow rates.
2. Plate efficiency can be predicted more accurately
3. The plate column operation is considerably smooth.
4. The cooling arrangement can be provided in a plate column.
5. The plate column provides stage-wise contact.
6. When the liquid causes fouling or deposition of solids, even though the tray is blocked up, it is easier to clean it and manholes can be provided over the plate.

plate columns

Plate (Tray)

Packed column

1. Packed columns are more suitable for low capacity operations.
2. Packed columns are particularly useful in the field of vacuum distillation. Here column pressure drop is of paramount importance to minimize the pressure and temperature at the bottom of the column.
3. For separating heat-sensitive materials packed columns are useful because the liquid hold up is low.
4. When corrosion is a problem packing may be the only answer.
5. Pressure drop per unit length is less in a packed column.
6. The packed column provides continuous contact between the vapor and liquid phases.
7. Packed columns are suitable for handling a foaming system.
8. Modern high capacity pickings are available in practically any material.
9. The total weight of the packed column is less due to the use of low weight and high capacity packing.

A packed column with different packing

Disadvantages

Plate columns

1. The foaming system reduces the performance of plate columns. Anti-foaming agents can be made use of to suppress the foam.
2. The liquid hold up is very high. Therefore the pressure drop is very high.
3. For corrosive liquids, the cost of the plate column is too high due to the use of corrosion-resistant material.
4. Supporting the structure required is costly.

Packed column

1. HETP and HTU prediction may not be very accurate.
2. Packed columns are not suitable for very low liquid rates.
3. The provision of a cooling arrangement is difficult in packed columns.
4. Removal of side stream is not possible in the packed column.