QUALITATIVE REASONING AND OPTIMIZATION OF CHEMICAL-ENGINEERING PROCESSES

A qualitative model can be developed by two main ways; by abstraction of quantitative equations or by using e.g. a flowsheeting program to e valuate derivatives, from which the qualitative model is generated by using either direct modeling or linear synthesis. Two different modeli ng shells for qualitative model development are described. An applicat ion to a qualitative decision support system is represented. For quali tative model simplification the following methods are proposed: ignori ng equations, partial modeling and linearization. The number of soluti ons from a qualitative model can be restricted by using a qualitative question or a projection. Spurious solutions can be eliminated by nonc ausal, causal and functional constraints. The principle of qualitative optimization is presented. Qualitative optimization is defined as an activity striving to improve the value of objective function by the me thods of qualitative reasoning. Also an extension to qualitative vecto r optimization is described. An approach to flexible semiqualitative r easoning is described which can accept several types of data. Same equ ations can be used for both quantitative calculations and qualitative reasoning. Evaluation rules are used to evaluate the type (accuracy) o f data after every operation.