1 reply to this topic

[icebear]

Hi there

I am doing my senior design and I want to evaluate 3 columns separating Benzene, Toluene, and p,o,m Xylenes. I need to set them up in a pressure cascading arrangement...all I know about this is that the products of the Toluene column are sent into the reboiler of the Benzene column (in my case). I don't care about the third column that much as of now.

My question is that how do you set that up in Hysys3.2? Do you use a refluxed absorber column and a separator to send the feed back into the benzen column through a heat exchanger to which is the toluene columns product feed is connected to...if so how do you go about doing this connection.

Any papers on this topic would be of a lot of help and also any feedback and help is appreciated...

Thank you very much

[Zauberberg]

Icebear, this is an interesting topic: the process itself and the way of configuring the flowsheet in process simulator.

I don't know how exactly your application looks like - do you fractionate pure BTX stream, or it is a mixed feed from Naphtha Reformer or Pygas Hydrotreater unit, or something else - the configuration of columns is very important. But here is what you can try to do... I made this template once, for simulating the tower with recirculating thermosyphon reboiler; as you may know, HYSYS offers only kettle-type reboilers which are equal to one theoretical stage of separation. So every time when there is some other type of reboiler, certain changes have to be made in order to represent the system in a correct manner.

1. See uploaded case flowsheet, how I represented recirculating thermosyphon reboiler without baffle by using phase separator vessel, heater, mixer/tee and recycle arrangement.

2. By using heat balance operation, try to link your toluene bottoms product cooler duty with the reboiler duty in the first column.

If you can upload the flowsheet showing your system configuration, maybe I can think up of something more helpful. This was only an advice for possible ways of thinking.
Greetings,

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