Maintenance-based strategies for environmental risk minimization in the process industries.

Industry, environmental agencies and the scientific community have all emphasized the need to include environmental impact considerations next to profitability objectives in the design phase of modern chemical processes, responding to the increasing social concern over environmental degradation in the past years. Most environmental impact assessment and minimization approaches, however, are rather qualitative, providing general guidelines. In this work, to overcome their limitations and rigorously represent the defining elements of environmental risk, i.e. the mechanism of occurrence of unexpected events usually related to equipment failure and the severity of their consequences, detailed process, reliability and maintenance characteristics are incorporated within a process optimization framework. The objective concerns the optimization of overall process performance defined as a system effectiveness vector characterized by both the environmental and the profitability functions of the system. Implementation of the framework on a process example identifies the optimal combination of process design and operation as well as preventive maintenance strategies that accomplish the conflicting environmental and profitability targets and quantifies the existing trade-offs between them.