4 replies to this topic

[Himanshu Parikh]

I am working on one project for hexane and methanol seperation by distillation. I would like to design distillation coulmn, can any body help me out for finding distillation column height, tower diameter, type of column, packed height require/
Total flow rate is 3300 lits/day, Hexane compostion by vol 90% and methanol by 10%. Hexane is top product whoile methanol is bottom product. Steam is avaailable .

Is any body guide me or can send excel spread sheet with VLE Data as i do not have these data.

Himanshu

[breizh]

Attached the link where you can find the VLE :

http://infosys.korea.../kdb/index.html

Click on hydrocarbon (left) , then you will get access to VLE , enter the componants and eventually you will get your data .


Hope this helps

Breizh

Edited by breizh, 19 June 2011 - 06:26 AM.

[Madhan Kumar]

Dear Himanshu,

Methanol and Hexane forms azeotrope , hence separation by fractional distillation in to purer compound will be difficult.
I would suggest liquid liquid extraction using water to separate methanol from hexane, separating aqueous layer containing methanol and organic layer as hexane.


Now your system will be methanol & water which can be separated easily.

Hope this may help you.

Cheer's
MK_Chem

[paulhorth]

Himanshu,

Have you actually studied chemical engineering at university? Beacuse what you are asking for is the content of a number of lectures on a typical university course. In my view, this forum is not intended to provide degree-level distance learning, but to deal with specific questions.

You could start by reviewing your old lecture notes, if you were there.
Here is a summary of steps to tackle a typical distillation problem:

• do a mass balance.
• decide on the required purity of the overhead and bottom products, This has a major influence on the column design.
• decide on the column pressure. This is driven by the temperatures you have for the heating and cooling utilities.
• determine the best combination of number of theoretical stages and reflux ratio neede to meet your product specs. This used to be done by hand but can now be done by running a simulation package. This is the heart of the design process and requires process design experience.
• You now have the reboiler and condenser duties for your chosen reflux ratio. Decide if these are reasonable, then determine the heating and cooling utility flowrates..
• column diameter is determined by the vapour and liquid flowrates in the column, and the tray design, the height is determined by the number of actual trays (theoretical stages divided by tray efficiency).

PS - I didn't know there was an aeotrope, as MK_CHEM says. In that case, forget the above, since distillation won't work.

Paul

Edited by paulhorth, 19 June 2011 - 07:44 AM.

[cnaren]

This is an interesting problem, and you can find some data to get you started here http://www.scm.com/D...ial/page44.html. MK_CHEM is tight, the two do form an azeotrope. But one that can be separated.


Step 1 - For a distillation feed of 150 kg/h, you can get 90 kg/h relatively pure hexane from the bottom. The top would be 60 kg/h with about 25% methanol & 75% Hexane (azeotrope - all in weight fractions).

Step 2 - The top fraction can be subjected to a phase separation, and you will get a lighter fraction quite close to your feed composition – this can be sent back to the distillation column. The heavier fraction would contain more methanol and less hexane.

Step 3 - If you send this heavier fraction into a distillation column, you would get methanol at one end and the azeotrope at the other end. You can send the azeotrope back to phase separation.

There is probably an easier way of doing this, and I hope others can help you out. It may be worth looking at how the Methanol gets into Hexane in the first place and tackle the problem at source.

I am working on one project for hexane and methanol seperation by distillation. I would like to design distillation coulmn, can any body help me out for finding distillation column height, tower diameter, type of column, packed height require/
Total flow rate is 3300 lits/day, Hexane compostion by vol 90% and methanol by 10%. Hexane is top product whoile methanol is bottom product. Steam is avaailable .

Is any body guide me or can send excel spread sheet with VLE Data as i do not have these data.

Himanshu