I am working on Enhanced Distillations schemes for separation of azeotropic mixtures. can i get the suggestions regarding this topic. Which distillations Schemes should i opt and what should be my choice of azeotropic systems. I have to work on Aspen Plus, no experimental work will be possible.
The usually way to break an azeotrope is to add another component (like toluene for etahanol water) changing pressure may also work. The other techniquie is to use a different separation process (freezing, adsorption, etc) for all or part of the separation process
Thank you all for your comments. I want to do some novel work in my project, Basically want expert advise for that.
@Rick Manner Sir. I have selected some azeotropic mixtures but want to work on few more which be very interesting for for work. Can you suggest some,
I don't actually know very much about azeotropes: but here are a couple of links that might help: Good Luck
http://cool.conservation-us.org/waac/wn/wn28/wn28-3/wn28-304.pdf
http://folk.ntnu.no/skoge/publications/thesis/2000_hilmen/Thesis_Hilmen.pdf
Farid Benyahia thanks. Did you mean experimental data for vapor-liquid equilibrium or some other thing. Please clear.
sir that data is only used to compare our VLE data so that the best suitable thermodynamic ,odel can be selected...simulated resiuts can't be validated with that data.
Asma, I'm not sure I understand your point. Isn't choosing a thermodynamic model because it fits the availbe data better than other thermodynamic models a form of validation?
I suggest you try to break an azeotrope by using two columns running at different pressures. Many but not all azeotropes from the standard tables in CRC hand book can be broken in this way. It allows you to experiment with double effect heat exchangers as condensers and reboilers also compressors.
Second you can model breaking an azeotrope of the butanol water type where the condenser gets two liquid layers that are decanted and redistilled in separate columns. Beware of the NTRL property set. If it is optimized for distillation, as in the usual case, it may get the decanter wrong. This is an example of a continuous function trying to describe a discontinuous graph. Remedy is to separate the upper and lower parts of the x-y diagram into different flow sheet sections and declare different Uniquac property sets optimized for each.
Asma, are you familiar with the Ryan-Holmes Process? It is used to separate the azeotropic mixture of ethane and CO2. Say you have a feed that is 40% CO2, 30% ethane, 15% propane and 15% n-butane. If you feed that to a distillation column, you can get maybe 65% CO2 at the overhead, not purer. at the bottom, the ratio of CO2 to the ethane should be 0.0035. TO get a better separation, you can feed a butane stream to the top of the column. It will enable you to get a 90% or higher CO2 purity. Then you need another distillation column to take the bottom of the first column and separate the ethane and propane from the butane. Cool the butane and recycle part of it to the first column.
It is a neat project for you. Assume that the feed is at 600 psia. You will also need a multistage refrigeration cycle. You can also keep it simple and use Peng-Robinson for this. You do not need to research the VLE. If you have any questions, let me know.
C4 separations have always been of interest to many and several C4 fractions are azeotropic or very narrow boiling systems. I keep hearing about a solvent being use to increase the relative volatility and break the azeotrope, if present. I do not know what the solvent is, but maybe you can google it.
Somebody above mentioned divided wall columns. To understand divided wall columns, read up on "distributed distillation". again, let me know if you have any questions.
@ Jerry Decker sir. Thank you so much for your valuable suggestion. I will try to work to butanol-water azeotropic mixture. thanks once again.
@ Hazem Haddad Sir. Thanks for the idea which you have provided to me. But sorry to say that i am unaware about the Ryan-Holmes Process . Can i have your email ID so that i can discuss in detail about your suggestion.
Asma, Here is a link to some information about Ryan-Holmes:
http://slideplayer.com/slide/3400284/
There are many ways to overcome azeotropic distillation problem. You can use two distillation columns with different pressure at each column (pressure swing distillation). I have used this technique for many mixtures and it is really powerful solution.
I suggest acetic acid and water to study the azeotropic distillation. I know that there is not azeotrope between these two components. However the relative volatility for high purities of water is close to 1 and the conventional distillation cannot be used for high purities of acetic acid.
I suggest making a comparison of several alternative technologies using economic and environmental indicators. The best way is to carry out a multi-objective optimization (2 objectives: Economic and Environmental) of the alternatives to obtain the pareto diagrams. I suggest using the Eco-Indicator 99 as an environmental indicator.
Article The Eco-Indicator 99: A Damage Oriented Method for Life Cycl...
The WAR algorithm is also an interesting option as an environmental indicator.
It is important that you choose an azeotrope that has enough experimental data to perform the validation of thermodynamic properties, not only phase equilibria but also properties such as density, Cp, enthalpy of formation, viscosity and among many others.
An exemplary case of a question-answer session !
The question became nicely defined in course of free & frank discussions.
Hope, your research project at the Aligarh Muslim University (AMU), India, is nicely progressing.
With best wishes,
ARB
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