Processes for Distillation Columns

All distilling systems use the same certain fundamental principles. Columns can be continuous, multi-stage, countercurrent, or vapor-liquid contacting systems. They are mostly designed to separate two or more materials at various temperatures. There are different types of distillation columns for various processes. We will tell you more below.

Packed Beds

The beds are used often for absorption purposes which can be useful in many industries, such as oil and gas. Additionally, they are used to distill vapor-liquid mixtures. Packing beds provide a large surface area for liquid-vapor contact to increase the effectiveness of the column’s performance. Packing bed types include random, packed, stacked packing, dumped, and others. These types of of columns can be used to recover solvents. Advantages include the ability to handle corrosive materials and thermally sensitive liquids, lower pressure drop than plates, and are cost efficient when the column’s diameter is under 2 feet / 0.6 meters.

Plates

This distillation process is one of the most widely used across the globe. The height of the column all depends on the number stages to achieve the desired purity and separation. Generally, the feed enters the plate column towards the column’s middle. The less volatile components  transfer from the vapor stream to the liquid stream due to concentration differences. The most volatile components exit the condenser as a vapor. The least volatile component or components exit via the reboiler in the liquid stream. Plate distillation columns are most often used to recover solvents from process wastes. They can handle high liquid flow rates effectively, cooling coils can be added for cryogenic applications, and they are most effective when the column’s diameter is larger than 2 feet / 0.6 meters.

Cryogenic

A cryogenic distillation column uses heat exchangers and cooling coils to lower the interior temperature. Cryogenic gases are fed into this cold box and distilled at low temperatures, usually under -238°F / -150°C. The column can use a plate design or packed bed. However, plate columns are usually the choice given that packed bedding is less efficient at lower temperatures. Applications seeking air separation is the general use for this process. They are useful for producing large quantities of high purity oxygen, they can produce products in both gas and liquid forms, which is advantageous because many forms of cryogenic gas are cheaper to move as a liquid.

Vacuum

This process involves maintaining the column’s pressure by vacuum pump to lower it to the temperature needed to vaporize the liquid. It is useful in scenarios involving liquids with low viscosities, liquids that can foam or foul, or heat sensitive products. Oil refineries use vacuum distillation to separate impurities and lighter hydrocarbons from the heavier hydrocarbons. Advantages include being able to operate in lower temperatures, it can help avoid degradation of some materials, and is more cost effective than separation of components at high temperatures.

The AMACS team leads the industry in manufacturing and installing various types of components for distillation columns, including trays, packing, and much more. Contact us if you need help choosing the right solution for your industry and application.