Should You Use Packing or Trays for Distillation?
The team at AMACS are experts in helping you select process column internals, such as packings and trays. We are constantly asked which perform best for a particular operation or application. Unfortunately, there is no one size fits all, simple answer. Below we will give you a general guide on whether you should use packing or trays for distillation.
Understanding the Distillation Process Before Choosing Packings or Trays
In lay terms, think of a glass of raw orange juice complete with pulp, seeds, skin bits, and more. What would it take a tower internally to turn raw juice entering at the top into clean juice ready for drinking at the end?
The distillation process is generally made up of a required range of vapor and liquid ﬂow, desired physical properties of the vapor and liquid throughout the tower, and they all need to be selected to deliver the final product of the separation, quickly and efficiently. This data will also help you select how many stages your tower needs to achieve the purity of the final product. Other factors for the distillation process to consider include:
- Maximum temperature.
- Operating temperature.
- Ongoing chemical reactions.
- Tendency to foul.
- Corrosiveness and toxicity of chemicals.
- Contamination sensitivity.
- And many others.
Packings Versus Trays for Distillation
Tower internals are often selected by desired liquid rates. For example, applications with liquid rates of 30 m3 /m2 -h and above generally use trays. Trays are also preferable where fouling issues may arise. Opt for packings (structured) in applications with lower liquid rates and for when you want to reduce column pressure drop. Choose random packings in higher liquid rate applications, as well as when you desire a reduced pressure drop.
There are also other considerations when selecting packing or trays. For example, many distillation towers can be very small. Towers with a diameter of 2 feet or under often use random packing or trays (cartridge tray assemblies) to meet the construction demands. Other towers can have diameters of up to 30 feet or more and experience hydraulic gradient issues that only packing can address. If looking to save money, trays plus vessel is usually the best way to go if it meets your distillation demands. Of course, many other factors come into play such as high or low pressure applications, vacuums, pressure drop sensitive applications, low liquid or vapor ratio needs, applications that foam, non-metallic needs, and many others. Additionally, many applications use multiple feeds and products to achieve the desired end result. In these and all cases, it is essential to select experts in the area to help you choose the right packing and/or trays the first time.
The AMACS team are experienced experts in all things trays and packings. We can help you select the best choice for the most efficient results at the most economical cost. AMACS manufactures these products for a variety of industries such as petrochemical, water treatment, food and beverage, oil and gas, and many others. Contact us to help you sort through the numerous combinations of packings, trays, and more for your exact process.