Analysis of gas stripping during ethanol fermentation-I. In a continuous stirred tank reactor
Journal
Chemical Engineering Science
Journal Volume
45
Journal Issue
5
Pages
1289-1299
Date Issued
1990
Author(s)
Abstract
The method of product removal from the fermentation medium by applying gas stripping as a means of preventing product inhibition and of improving the productivity in ethanol fermentation (GSEF) using a stirred tank reactor has been analyzed. A modification of the Ghose-Tyagi specific growth rate model and the Luedeking-Piret production model have been used to formulate and simulate the GSEF model. The advantages of using gas stripping are demonstrated, namely: (1) the cell concentration increases with increase in the stripping factor for a given dilution rate, (2) the substrate consumption increases by the stripping factor for a given dilution rate, (3) ethanol concentration in the broth decreases with increase in the stripping factor for a given dilution rate, and (4) ethanol productivity increases with increase in the stripping factor for a given dilution rate. Furthermore, the maximum total productivity achievable at a given stripping factor and the corresponding optimum dilution rate is presented. It is shown that, if the kinetics have a product-substrate inhibition, they exhibit multiple steady states and an additional constraint is required for the dilution rate. This limiting dilution rate as a function of substrate feed concentration with various values of stripping factor is also presented. It shows that, below a certain feed concentration, the limiting dilution rate is independent of the stripping factor. © 1990.
Type
journal article