One of the most important factors in unit operations is distillation. The distillation and cooling processes occur by utilizing the internals. Internals, as important as they are to the operation, are not easily accessible. This is why it is imperative to choose the proper internals for the tower. Having the best option possible will allow for less down time and more production.
Here is a list of differences between packed and tray towers as well as the advantages of choosing tower packing technology.
Tray Tower Operation
This type of tower creates liquid holdup to achieve optimal separation in the vapor-liquid mass transfer. The tower has stacks of horizontal trays and a weir on each tray creates the holdup. The liquid runs across the trays and then flows over to a downcomer to the next stage of separation. Trays used in those towers can be different, some of the models being valve trays, sieve trays and bubble cap trays.
Packed Tower Design and Applications
Tower packing creates a large amount of surface area per volume where the liquid-vapor mass transfer will occur. The vertical positioning of the surfaces allows for far more even flow during which the vapor and liquid remain in continuous contact with the packed bed surfaces. Unlike the step*based contact of the tray bed tower, this process is uninterrupted, improving flow and increasing the overall volume of processed vapor.
Random Vs. Structured Tower Packing
There are two primary models of packed bed towers, the random and structured tower packing versions.
- Random Tower Packing is when the tower is constructed from a variety of metals, ceramics and plastics which provide the surface areas where distillation is to occur.
- Structured Tower Packing offers a better usage of surface areas and lower pressure drops which might hinder the flow. It mainly employs corrugated sheets or perforated metal, wire mesh and certain grades of plastic, such as PTFE. The structure this creates is very open with exceptionally low flow resistance and a high capacity and efficiency levels.
There are certain cases where you would prefer random packed beds over the structured modules, and sometimes plate towers may be preferable, but whenever applicable, the structured packed tower technology is much more efficient and cost effective than the alternatives.
This was a brief overview of the packed tower design and applications. If you’d like to consult our specialists and decide which of them is best for your process, feel free to contact us.
