Design of spray distillation apparatus for ethanol purification

Abstract

One of the major problems in bioethanol production is the high amount of energy required for distillation. Alternative methods such as vacuum distillation and pervaporation were developed, however energy required to obtain vacuum condition still pose some problem. Utilizing diffusion and evaporation in droplets may further lower the energy needed for separation since it increases the droplet surface area. This research aims to develop a sprayed feed distillation column for ethanol purification and evaluating its performance in various feed concentrations. Mass, energy, and momentum balance of droplet mixture was used to develop droplet model behavior in the column. Numerical simulation of droplet behavior model was used to determine the height of the column. From this simulation, the ideal droplet falling distance for evaporation was estimated to be 50.84cm. A prototype was assembled using diameter of 25cm and height of 70cm, equipped with spray nozzle. Using 250ml feed with 12-70% v/v ethanol concentration, the process could produce output concentration of 83-93%. Whereas feed concentration of 96% ethanol could produce ethanol concentration output up to 99% v/v. The process could recover 40-80% of ethanol from the feed.