ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
On-line measurement of the important state variables in fermentations, particularly cell mass concentration, remains a difficult problem. However, a number of secondary or environmental variables can be measured conventionally and on-line, such as pH, and CO2 and O2 in the exhaust gas. Stephanopoulos and San (1984) have developed a modeling approach, based on species balances, that provides relations between the environmental and important state variables. Using such a model, the important state variables can be estimated in principle from more easily accessible on-line measurements.In this article, a new adaptive estimator is developed, incorporating as its basis an underlying nonlinear model so as to utilize the best possible a priori process knowledge. Base addition rate and CO2 offgas concentration are measured on-line and periodically. Cell mass measurements are incorporated infrequently and even at irregular sampling periods, thus providing a very flexible scheme. Only a single adapted parameter is required to match the model to the plant operating characteristics. This simple but rigorous model form results in an estimator that is easy to implement and to tune and which exhibits long-term robustness due to its multirate feedback structure. Experimental results from a laboratory-scale continuous fermentor show that such a cell mass estimation scheme yields excellent performance both open-loop (without control) and as a part of conventional and nonlinear adaptive control approaches.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690390214
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