Ethanol Production (May 2007)

­ We document an experimental study to optimize yield of an ethanol distillation process. The yield is expressed in terms of concentration of the ethanol obtained, and the profit from the process. Concentration is a function of six input factors that can be varied within a given range. Profit is a function of the revenue (which depends on the concentration of ethanol achieved) and costs (which vary with the input factor settings). We started by determining a practical operating range for the six input parameters where the constraints of the system (pressure in the distillation column and holding tanks) were not violated. We then conducted a factorial experimental analysis and used a response surface method (path of steepest ascent) to determine an operating point where the desired concentration level is achieved. Finally, we used a space filling experimental design in a narrow region around the operating point to determine the effect of various input parameters on robustness and profit.