Quantifying human error probability in independent protection layers for a batch reactor system using dynamic simulations

The batch processing facilities with features involving in large-scale human intervention are generally considered to be relatively hazardous processes due to frequent change in operating conditions. Therefore, sufficient protection layers should be implemented against the hazards inherent in the batch processing facilities, especially for batch reactor systems. The human operations involved in the batch process play an important role to maintain process production and also take responsibility for reducing risks in specific possible accident scenarios. However, in practice, a number of companies initially did not take any credits for human actions in Layer of Protection Analysis (LOPA) or were overly optimistic in a few cases, which result in unwarranted safety expenditures or inadequate risk reductions. In this study, we propose a simulation-oriented methodology for quantifying human error probability (HEP) in independent protection layers (IPLs). The methodology integrates dynamic simulations with human reliability analysis (HRA) to give a comprehensive analysis of human actions. Case study for a batch reactor system shows that risk reductions of human response are expected to be greater than that determined using other methods. The present study provides a solution for analyzing the risk reductions of human elements within the IPL and serves as a reference for improving the emergency response for operators.