Date of Award

Fall 1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Demetri P. Petrides

Second Advisor

Piero M. Armenante

Third Advisor

Basil Baltzis

Fourth Advisor

James Geller

Fifth Advisor

Dana E. Knox

Abstract

Problems related to process design with environmental considerations have been studied in this dissertation. A new heuristic design methodology has been formulated with the objective of minimizing the adverse environmental impact of chemical processes.

This hierarchical methodology starts with the definition and analysis of a process flowsheet followed by quantification of the process environmental loads. The quantification of environmental loads is an essential aspect of this methodology, because it serves as the comparative measure for environmental performance.

If the calculated environmental loads do not satisfy the environmental constraints (e.g., regulatory limits), waste minimization is investigated in the following order:

  • Pollution prevention; process modifications aiming at pollution prevention are identified, prioritized, and evaluated.
  • Pollution control; pollution control flowsheets are synthesized, analyzed, and evaluated based on the environmental loads.

The main focus of this research has been the partial implementation of this methodology on the computer to assist in the synthesis, analysis, and evaluation of pollution control flowsheets. Two separate programs have been developed:

  • WasteMin Expert, a knowledge-based system which provides an organized framework for assisting the designer in the synthesis of pollution control flowsheets. It is an interactive rule-based expert system, which follows the task decomposition paradigm to accomplish the flowsheet synthesis task. The output of WasteMin Expert provides a conceptual flowsheet in the form of an ordered list of key unit operations for pollution control. This list serves as a good starting point for the creation of detailed designs using a process simulator.
  • EnviroCAD, a simulator developed for the analysis and evaluation of pollution control processes. EnviroCAD includes a variety of unit operation models used for waste treatment and disposal. EnviroCAD accounts for environmental loads on the basis of individual pollutants as well as aggregate environmental properties. Tracking the fate of individual pollutants facilitates retrofitting efforts to achieve the environmental objectives.

The methodology has been demonstrated in several examples, including the design of a wastewater treatment facility. The results of this case study are in good agreement with field data.

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