The Study Of Process Controlling In Ethanol Fermentation

The process of microorganism fermentation had the characteristic of nonlining, Changability and posteriority, the inner mechanism of which was very complexed. The traditional metheod cannot measure some important parameters in the process of fermentation on line, which maked it very difficult to control the whole process of fermentation optimizationally. This article taked the on-line detect equipment which commonly used on industrial fermentation study the process controlling of high cell-density and intensity ethanol fermentation, and then took the technology of software sensor pre-estimate the glucose concentration in the fermentation process, which in order to establish an on-line feeding method of glucose feedback. The main methods and results were as follows:1 Cultivating condition of Saccharomyces cerevisiae in this shaking flask medium was optimized and then obtained the best culture condition: using YEPD as the seed medium, culturing seed broth for 12 h,initial pH 4.5, inoculation size 8 %, initial glucose concentration 40 g/L.2 The effect of feeding strategy on ethanol fermentation was investigated using stirred tank fermentor,. It showed that, in the prophase of fermentation, glucose feedback feeding was advantaged to thalli growth; in the anaphase, discontinuous feeding was advantaged to the synthesize of ethanol, and then, we determined mixed feed as the relatively suitable feeding mode.3 In stirred tank fermentor,we studied the high cell-density and intensity ethanol fermentation through the dissolved oxygen control strategy, and gained the optimize strategy(stir 100 r/min, aeration rate 0.22vvm, aeration time 12 h): the biomass amounted to 0.55～0.60 billion/mL , the fermentation intensity reached 2.71 g/L·h , and fermentation time was 48 h.4 Taking the theory of software sensor as the study basis, we put forward the method of Date-driven aiming to measure the key biomass in the fermentation process. The key of the method lied in that it takes the Principal Component Regression(PCR) as the way to realize the software sensor and then took this algorithm to pre-estimate the concentration of residual sugar in the process of ethanol fermentation, the net test also testified the feasiblity and effectiveness of the method. On this basis, this thesis designed a digital control system for the bio-fermentation to realize the on-line control of the glucose concentration and feeding in the process of ethanol fermentation. The study provided a new way for the on-line measurement of the key biomass and the feeding strategy in the process control.