(286a) A Chemical Process Design Framework Including Different Stages of Environmental, Health and Safety (EHS) Assessment

Needs are growing to include environmental, health and safety (EHS) aspects in every decision-making throughout process development. In particular, decisions on reaction path, solvents, unit operations and operating conditions have a significant influence on the EHS performance of the process. Various methods have been proposed to reflect such aspects of early stages into decision-makings (e.g. Waste Reduction Algorithm by Hilaly and Sikdar, 1994; Environmental Hazard Index by Cave and Edwards, 1997; Inherent Safety Index by Heikkilä, 1999). Selection of these evaluation methods should be appropriate in order to cover EHS aspects comprehensively at every design stage. Some authors distinguished different stages of process design, and proposed two-steps procedures with one environmental evaluation method using different amount of available information (e.g. Hoffmann et al., 2001; Chen and Shonnard, 2004).

In this work, we present a novel framework for the design of chemical processes. This framework includes four design stages and aims at a multiobjective decision-making at each stage using suitable EHS assessment methods in conjunction with technical and economic performance indicators. The different stages that have been defined comprise decisions on the synthesis route, the general process structure, the type of unit operations and the corresponding operating conditions. We reviewed a set of existing EHS assessment methods and selected suitable ones for each design stage, to cover EHS aspects comprehensively in combination with technical and economic issues.

The proposed framework is demonstrated on the design of methyl methacrylate (MMA) processes. By mimicking the framework, several reaction routes for this chemical are eliminated in a step-by-step procedure to obtain the most promising routes together with their optimal process structures and operating conditions.