OPTIMIZATION OF FERMENTATION PLANTS

Abstract

Techniques for estimation of investment and manufacturing costs in fermentation are discussed. A method for optimization of fermentation Plants as whole is described. 5 It necessitates knowledge of a model of the biosynthesis and equations correlating investment and manufacturing costs to the size of equipment. The Minimization of the non-linear objective function in a non-convex field is obtained by a two step method. Optimization in fermentation industry may have numerous aspects. One may envision improving the growth rate, the production rate or the yield in compound biosynthesis. In this case, the main control parameters are : substrate concentrations, temperature, pH, aeration and agitation etc... Since a mathematical model of microbial cell-growth has been formulated by Monod (1), the kinetic pattern of various fermentation systems has been intensively studied. The number of publications in this field is strongly increasing (2,3,4,5,6). The problem concerning the reduction of manufacturing costs such as those of steam, energy of agitation and aeration, consumption of air, water and raw materials belong to another category of optimization. Okabe and Aiba have recently presented solutions to these problems (7,8,9,10,11). The purpose of this paper concerns the approach of a global optimization of a new plan supposing that the annual production of a fermentation product is given, then the optimization consists in determining the size of the fermentor, power of agitation and aeration system, size of heat exchangers, pumps, filters, centrifuges etc... the required condition for temperature, pH, dissolved oxygen, substrate concentration etc... so that the investment capital and annual expenditure for the production be minimized. Since the same control variables and equipment are used in most fermentation industries, we consider that the method proposed, as regards yeast production, will also apply to various other production.