Abstract
The number of products used as agro-chemicals, food additives, flavors, aromas, pharmaceuticals and nutraceuticals which are made by fermentation or extraction from plants has increased significantly. Despite this growth, initial predictions for a potential product purification process for these complex mixtures remains entirely experimentally based. The present work represents an initial study to demonstrate the benefits of a systematic approach. For process development of chemically well-studied systems model based process design methods are already available. Therefore the proposed approach focuses on a method for the efficient characterization of the physical properties of the key components. Once this is adequately defined, unit operations and their potential to separate the feed components can be modeled. The current state of research is discussed. Based on this evaluation the most efficient method for conceptual process development has been identified and further developed. The resulting methodology consists of model-based cost accounting accompanied by experimental model-parameter determination. The latter is carried out at in miniaturized laboratory-scale measurement cells for each unit operation using the complete original feed. The model-based modelparameter determination from these experiments is accompanied by a comprehensive error analysis. The experimental plan currently includes the determination of thermodynamic equilibrium conditions in the mixture directly from the raw material mixture. Transport kinetics and fluid dynamic parameters are first estimated from known correlations or preexisting knowledge. Later on these parameters are determined exactly in mini-plant experiments. Furthermore, biological and botanical-based guidelines are developed to identify thermodynamically favored basic operations. Finally, the developed approaches are successfully validated using two plant extracts. Firstly, it could be proven that the botanical pre-selection can reduce the experimental plan significantly. Secondly, it was shown that the experimental equilibrium data of the kinetics and fluid dynamics can have a significant impact on the separation costs. Therefore, detailed rigorous modeling approaches have to be chosen instead of short-cut methods in order to make any valid process development conclusions or to further optimize the system.
Highlights
The design and development of a separation process passes through multiple phases e.g. product development, basic and detailed engineering
To make decisions between alternative unit operations and their sequencing requires models of these unit operations which are sufficiently precise. These decisions are in most cases quite in a narrow range, they can not be filed on the basis of a rough estimation like it would be if only separation coefficients between target and side components are considered if so called short-cut-calculations would be applied
The aim of this work is to propose and prove an initial systematic methodology and the necessary tools required for the conceptual process design of complex mixtures
Summary
The design and development of a separation process passes through multiple phases e.g. product development, basic and detailed engineering. The possibility of cost effective improvements in process management which can be developed with increasing knowledge, decreases (see Figure 1). Over 70% of the manufacturing costs are already defined in the conceptual process design (CPD) and the first development of the first flow-sheet set-up [2]. The fundamental limitation which has to be taken into account is the limited availability of feedstock, usually of the order of a few liters. At this stage of the project, when the probability of project failure is high, there is limited analytical and experimental resource to be exploited
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