The Development, Documentation, and Applications of the Integrated Environmental, Health, and Safety Index (IEHS)

Abstract

During the conceptual design phase of industrial processes, there is a need to make quick decisions on the screening and selection of alternatives. These decisions are typically based on techno-economic criteria and sometimes include environmental aspects. Safety considerations usually come as an afterthought. A designer charged with developing the conceptual process flowsheet for a new plant often cannot access the information needed for conventional safety analysis due to the lack of sufficiently detailed design data and time restraints. This is heightened in operations without extensive historical data such as processes that are small, produce specialty chemicals, or use novel processes. Given the significant gains that can accrue by including safety considerations during the conceptual design phases, there is a critical need to develop systematic approaches that aid the process designer in incorporating safety during the early stages of process design. This thesis turns a literature index into a process flowsheet development tool. The revised index is referred to as the Integrated Environmental, Health, and Safety index (IEHS). It accommodates the nature of early process synthesis and conceptual design work. It also accounts for categories not directly covered before such as maintainability, process control and overall process structure. The main focus of IEHS is to provide the designer with insights about the consequences of making design decisions and to provide a rational basis for the incorporation of safety issues on par with design methodologies and economic metrics. Through the use of IEHS, process designs failing to meet quantitative risk limits are eliminated from further consideration or revised to meet the desired limits early enough in the design work process. A case study is solved for the design of a dimethyl ether process to illustrate the applicability of IEHS in the early design phase.