Distillation Essay

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Distillation Abstract This report outlines the steps taken to separate a 50:50 by volume ethanol and isopropanol side stream. The resulting separation must contain no more than 3% alcohol impurity in each product. A laboratory column, run at total reflux, was utilized to scale up to a forty foot high by one foot diameter column. The laboratory column allowed the team to determine vapor velocities and HETP values for the 0.24 inch Pro-Pakq packing. HETP is defined as the height of packing divided by the number of theoretical column stages. The column consisted of four main sections: packing, controls, a reboiler, and a condenser. To complete the vapor velocity vs. HETP relationship, the vapor velocity must be found. The…show more content…
Finally, the actual packing height will be determined for the scaled-up column. Theory and Methods The primary goal of this project was to deterimine the design specifications for a one foot diameter by forty foot high packed distillation column. The laboratory was run at total reflux. Total reflux occurs when the entire overhead vapor flow is returned as reflux and all of the bottoms liquid is returned as boil up. Total reflux is useful for starting up columns, maintaining column operation when all or part of a plant is shut down, or for our purposes: determining column efficiency. However, since our column was a packed column and not a tray or sieve plate column, efficiency is measured not in terms of overall efficiency, but in terms of HETP. HETP is defined as follows: HETP = height of column packing y number of theoretical stages (1) There are two basic ways to determine the number of theoretical stages (Nmin): McCabe Thiele analysis and/or using the Fenske equation. Both of these methods will give Nmin, however, McCabe Thiele utilizes a graphical analysis and Fenske utilizes a numerical analysis. To use McCabe Thiele graphical analysis, the condition of constant molal overflow (CMO) must be met. The assumptions behind CMO are as follows (1, 117): 1. The column must be adiabatic 2. The specific heat changes are negligible compared to latent heat changes 3. The heat
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