A Novel Safety Control Hierarchical Architecture for Prevention and Mitigation of Critical Faults in Process Industries based on Defense-in-depth, Reactive Systems and Safety-diagnosability

摘要

Safety is an important issue that has increasingly been focused on. The reasons are the numerous accidents in process industries which require a hard look at current practices such as process design, process control, risk analysis and control, and risk assessment. Critical faults in process industries could lead to loss of lives, environmental damage and significant financial losses of property and equipment. Accidents typically result from the absence or breach of defenses or breach of security restrictions. The so-called defense-in-depth principle embodies the idea of multiple lines of defense and safety barriers along the accident scene; and this principle avoids ensuring the dependence of safety on a single element. Additionally, for several accidents, the identification of concealed faults and/or non observability of critical faults have been reported, during the evolution of faults following the accident, as relevant factors in the occurrence of catastrophic accidents. Finally, as process industries, are complex systems that interact with the environment, the disturbances caused by the environment must be properly diagnosed and treated by these systems. Based on these issues, this work initially proposes a safety control architecture that integrates the concept of reactivity associated with de principles of defense-in-depth, and safety-diagnosability addressing aspects related to critical faults prevention, mitigation and description of the development of failures. We believe that the safety control architecture is a change in paradigm contributing to risk analysis, risk and hazard control, and risk assessment.