3 replies to this topic

[riven]

In addition, i would like to know if a vacuum distillation column could be designed either as a tray or a structured packing?

Both can be used. I know for styrene distillation trains, the main reason for using structured packing is to have a low pressure drop across the column to avoid high temperatures in the column which in turn limited the amount of polymerisatiuon that occurs.

Vacuum systems some examples can be found at
http://www.graham-mf....asp?pageId=113

[Padmakar Katre]

I came across simplified drawing of vacuum distillation @ wikipedia recently for oil refinery. But now, I'm curious of how does a Vacuum Distillation for other types of chemical (monoethylene glycol column, Styrene distillation column and others) looks like. Does it has a features similar to those found at oil refinery as per attached?

Hi,
Vacuum distillation term is used to define the distillation column operating under vacuum compared with the pressure distillation which operates at either atmospheric of elevated pressures. The attached thumbnail of the column by you is merely an output of the sizing based on the operating/design parameters.

Next, I would like to know how does the column maintains a vacuum conditions in the vessel itself? Is there any devices attached directly to the vessel such as shown at the picture where it is connected to vacuum system for it to maintain at vacuum conditions?

There are ways to maintain pressure below atmospheric or simply vacuum, e.g. Vacuum Ejectors, Vacuum Pumps etc. The link given by Riven is useful to understand about how to create/maintain vacuum.

In addition, i would like to know if a vacuum distillation column could be designed either as a tray or a structured packing?

The decision is not so straight forward but with many basic assumptions/constraints like delta P allowed, Turn-down required and so on.

According to the column simplified drawing attached in previous post, the top & bottom of the vessel is attached to vacuum system & vacuum residuum. As of my experience on distillation column, it suppose to be connected condenser & reflux drum at the top, while for bottom it should be connected to a reboiler. Why does the features of the simplified drawing attached varies from what it suppose to be? Hope someone could enlighten me regarding this.

Read the Vacuum Distillation Unit portion and things will be clear about the column configuration.