1 reply to this topic

[keby9vam]

Hi,

I would like to confirm, when using a steam ejector for a vacuum distillation column, is it positioned on the top of the column? If so, where should I place the top vapour outlet nozzle of the column which will flow to the condenser?

Thank you

Regards

Viknesh

[Art Montemayor]

Viknesh:

It is my hope and expectation that your engineering professors and instructors have not failed to instill in you and your fellow sturdents the need and the capability of always making a sketch or a drawing of your engineering problem – when it involves a Unit Operation.

It is very important to know what physical changes take place in a Unit Operation – and that is what a Unit Operation does: it makes or creates a physical change in the process involved. For example, if you make a schematic sketch of your process, you should note that you can place the overheads condenser at the top of the distillation column or at the bottom (at grade). Most installations select the grade location due to the need of having convenient, safe, and less costly maintenance and inspection operations carried out on the condenser and the vacuum equipment. However, as you will deduce, this entails a “trade off”. Almost every engineering decision you will make in your professional life will involve a trade off. Nothing comes free. In this case, you have to invest in a pump and pumping costs to return a portion of the produced condensate back to the top of the tower as reflux.

If you install the condenser at the top of the column, this will entail large structural steel costs as well as platforms, railings, ladders, and lighting. In either case, you can install the steam jet ejector producing the vacuum at any position – usually on top and close to the condenser.

If you have further questions on this topic I recommend you furnish a sketch showing your proposed installation. That way our members can easily make comments directly on the sketch if it is done on an Excel workbook.