irst step in this process was to design the experiments in order to extract useful results, which would facilitate the scale-up process to the 1-foot in diameter by 40-foot high existing tower. In the design of experiments the voltage supplied to the reboiler heaters and the flow rate of cooling water through the condenser were varied. (Appendix B, p. 5-6) At each trial condition the composition of the reflux and reboiler was analyzed. The distillate and bottoms compositions of ethanol were used to step off stages at total reflux, which was the condition that the lab column was operated. This operating condition is where all the overhead vapors are returned to the column as reflux, and all the underflow is returned as boil-up. Total reflux gives the minimum number of stages required for a given separations. (1, p. 177-78) At total reflux the x-y line is the operating line and the process of stepping off stages was started with the distillate composition of ethanol. The HETP for each lab simulation trial was calculated using the minimum number of stages from McCabe-Thiele analysis through equation 1. The average HETP determined through McCabe-Thiele analysis was 3.76 inches, with a standard deviation of 0.5427.An alternate method of calculating the minimum number of stages was determined, Equation 2 was used to determine the HETP value. The Fenske results gave an average HETP of 4.55 inches with a standard deviation of 0.4939. The Fenske Method gives a comparable HETP result when compared to McCabe-Thiele results, but has a lower standard deviation. Hence, the Fenske analysis is more consistent that the McCabe Thiele analysis. A summary for the design of experiments with the corresponding HETP values for both methods is located in Appendix B, p. 5-6.Once the HETP was determined, the vapor velocity needed to be analyzed to generate the HETP vs. vapor velocity graph. Again, the two methods were analyzed to determine the optim...
