Effect Of Pulsed Steam Flow On The Ethanol Solid-State Distillation

Energy is the important resource for human survival, economic development and social progress, and the energy issue is an important strategic issue of common concern to all countries. One of the effective ways to solve this problem is using fuel ethanol instead of traditional energy sources, which is widely accepted and recognized around the world. Ethanol solid-state distillation technology has obvious advantages in saving energy, reducing pollution and reducing costs, etc., and important practical significance and research value. This technology originated from traditional liquor solid-state distillation technology in China. Steam is utilized in this technology to distillate the fermented grains for extraction of ethanol. Fermented grains are porous media containing multi-component solution, and thus the process combines evaporation of multi-component solution and heat and mass transfer in porous medium. Therefore, the mechanism of solid-state distillation process is essential for researching.This study is committed to exploring and analyzing the improvement of ethanol distillation efficiency. Pulsed steam flow was utilized instead of steady flow in the fermented grains distillation experiments. Under the same steam flow and temperature, the distillation experiments of fermented grains was conducted with steam flow of different pulsation rate,2Hz,1Hz and0.5Hz to investigate the effect of pulsation frequency. Experimental results show that the maximum distillation rate turns to be higher by12%, and the yield of ethanol increases from72%to85.3%when the pulsation frequency of steam flow steps down from2Hz to0.5Hz. It is concluded that, the efficiency of the ethanol solid-state distillation is improved with pulsed steam flow. The results of solid-state distillation with pulsed superheated steam flow in comparison with the experimental results using saturated steam show that, while temperature raised to120℃and130℃the final distillation effectiveness is almost same, but the superheated steam plays a positive-role in drying the fermented grains.According to the experimental results of solid-state distillation experiments with saturated pulsed steam flow and with the consideration of the mathematical modeling process in thin-layer drying, a mathematical model which is applicable to pulsed steam flow solid-state distillation process was established. The fitting between the predictions and experiment data is favorable.