IPA and EtOH Spearation via Distilation Column

[ChEtobe14]

Hi,

So I am wondering if anyone would have any ideas on to how to maximize the most of my data collection efforts into characterizing a distillation column that we are using in my senior design course to separate a mixture of IPA and EtOH. The column contains sieve trays, with 5 of them residing in the enriching section and 10 of them in stripping section. I will be operating this column at total reflux. We are asked to find a design based on the experimental data obtained to design a system that will recover 90% of the EtOH with a purity level no less than 85%.


I spoke to my professor regarding what data I need to collect, however I am not sure as to how to go about doing this. He said I need to use the HTU-NTU method and find the mass transfer coefficients. Problem is, I never learned this in my separations course. Another problem is, I cannot access the trays to attempt to analyze the compositions at each stage. I only have access to the product exiting from the top of the column.

I have only two manipulated variables the condenser water flow rate and the power input into the reboiler. Here is what I am planning on doing:

1. Start analyzing, by gas chromatography, different mixtures of IPA and EtOH. Generate a calibration curve base don that. Calibrate the water flow meter since it is unit-less and relate it to the amount of water exiting the condenser over an interval of 2 minutes. 5 different trials will be performed.

2. I am stuck :/ . I am not sure how to proceed from here to gather the required data needed for full characterization.

If anyone could be so kind as to point me in the right direction, I would really really appreciate it!

Thanks!

 

[Achy47]

Thank you for your question. It sounds like you have a challenging project ahead of you! In order to maximize your data collection efforts, here are a few suggestions:

1. Begin by thoroughly researching the HTU-NTU method and mass transfer coefficients. There are many resources available online, such as textbooks, articles, and videos, that can provide you with a basic understanding of these concepts. It is important to have a solid understanding of the theory behind these methods before attempting to use them in your project.

2. Since you do not have access to the trays in the column, you will need to gather data from the product stream exiting the top of the column. This will require you to measure the composition of the product stream at various points in time. One way to do this is to use a gas chromatograph, as you mentioned in your post. However, you may also need to consider other methods, such as using a refractometer or a density meter, to gather additional data on the composition of the product stream.

3. In addition to composition data, you will also need to gather data on the manipulated variables (condenser water flow rate and reboiler power input) and the product flow rate. This will allow you to calculate the mass transfer coefficients and other important parameters needed for your design.

4. It may also be helpful to simulate the distillation column using software such as Aspen Plus or HYSYS. This will allow you to input your experimental data and simulate different operating conditions to determine the optimal design for recovering 90% of EtOH with a purity level of at least 85%.

I hope these suggestions are helpful to you. Good luck with your project!