Raw Corn Simultaneous Saccharification Fermentation Of Ethanol Process Optimization And Dynamics Research

In recent years, the energy crisis and global warming have increasingly aroused the concern of the society. In order to solve these problems, people are hoping to find a new alternative energy instead of fossil fuels. As one of the promising and extensively used biomass energy souces, fuel ethanol is one of the best choices. Ethanol production by fermentation of starch materials with corn as the representative is the main production method in China. Different from the traditional fermentation, the simultaneous saccharification and fermentation is a combination of enzymatic hydrolysis and ethanol fermentation in the same fermentation tank. The method has the advantages of reducing energy consumption,simplifying fermentation process, reducing substrate inhibition, increasing ethanol yield and so on. But at the same time there are also many defects, such as parameters in the fermentation process don't reach the best condition and need to be further optimized; yeast,enzymes and other raw materials in the same tank make the fermentation process difficult to control and predict. To this end, this paper mainly aimed at optimizing the process parameters of the fermentation process, so as to find the optimal technological conditions. And the kinetics of yeast growth and ethanol production were compared, the dynamic model of the mass concentration of ethanol as a re-parameterization of the objective function was put forward.In this paper,the effects of three facators,fermentation temperature,yeast content,the addition of saccharifying enzyme, on ethanol yield were studied and following conclusion could be drawn. (1)With the increase of fermentation temperature, yeast content and the amount of saccharifying enzyme, the ethanol concentration increased at first and then decreased. With the fermentation temperature of 32?, yeast adding amount of 4.5 g/(g·raw material) raw materials, saccharifying enzyme content of 4.15 g/(g·raw material), ethanol concentration reached its maximum. (2) On the basis of single factor and through three factors and three levels of Box-Behnken combination Design and the application of Design Expert software dealing with the experimental data, the regression equation and plot of the response surface was worked out. Then the influence of various factors on the response value and the interaction of the various factors could be determined. Finally, the optimal preparation conditions were concluded that the fermentation temperature is 32.5 ?, the quantity of yeast is 4.42 g/(g·raw material), and the saccharifying enzyme amount is 4.20 g/(g- raw material).(3) The re-parameterized Logistic model and Gompertz model were used to describe the change of ethanol concentration over time under different amount of yeast during the fermentation. Their goodness of fit R2 was greater than 0.9500. Among them, the parameters of Pmax (maximum ethanol concentration) increased with the increase of yeast. ?(delay time)decreased with the increase of yeast. And the change law of Vmax (rate of ethanol production)is not obvious,which showed a small impact of adding amount of yeast on Vmax.