Integrated Synthesis and Analysis of Chemical Process Designs using Heuristics in the context of Pollution Prevention

David W. Pennington
Oak Ridge Post Doctoral Research Fellow, Systems Analysis Branch, NRMRL, US EPA.

The identification and comparison of process modifications is not typically practised consistently or routinely in the context of pollution prevention, particularly during the stage of conceptual design.  P2TCP (Pollution Prevention Tool for Continuous Processes) is a computer-based system, developed to help designers systematically identify pollution prevention opportunities.  The tool is applicable for continuous chemical processes and can be used during conceptual as well as retrofit design, thus facilitating the development of inherently cleaner processes.  Unlike other systems, case studies are used to validate P2TCP and to identify further extensions, not as the principal knowledge source.

P2TCP is based on a novel design approach.  Unlike hierarchical or step-wise design techniques, heuristics (knowledge based rules) are used to analyse each system of a chemical process (reaction and separation) independently for potential alternatives. Effects associated with the interacting streams, i.e. streams leaving the reaction system and potential recycles, are then taken into consideration to further reduce the number of options requiring consideration.

The effectiveness of this heuristic based approach has been demonstrated in a number of pollution prevention case studies.  Unlike hierarchical techniques, it is theoretically possible to consider all alternatives.  Furthermore, the case studies demonstrate that the number of design alternatives requiring consideration is not inhibitive.