Application of Human Factors Evaluation in Engineering Design and Safe Operation of Dense Phase Ethylene Treaters

Abstract

Ethylene treaters are widely used in the petrochemical industry to remove impurities from ethylene feedstock imported from pipeline networks or storage caverns. The safety concerns of dense phase ethylene treaters due to the reactive and highly flammable nature of ethylene are well known and studied. Under certain conditions, ethylene may self-polymerize and decompose violently with heat release. If vented too fast, ethylene will auto-refrigerate generating cold liquids that may cause potential brittle fracture hazards. Due to these safety concerns, it is a challenge to select the appropriate engineering design options for dense phase ethylene treaters and the associated regeneration facilities. Totally automated treater regeneration systems add complexity and instrument maintenance requirements and manually operated systems rely heavily on operator training and procedures. This paper presents a risk assessment method to evaluate the engineering design and safe operation options for dense phase ethylene treaters. The proposed risk assessment method integrates human factor analysis into the traditional HAZOP, LOPA and fault tree analysis to allow evaluation of automated, manual and hybrid approaches with a goal of selecting and optimizing design options to ensure plant safety.