Environmental risk assessment of low density polyethylene unit using the method of failure mode and effect analysis

The ninth olefin plan of Arya Sasol Petrochemical Company (A.S.P.C.) is regarded the largest gas Olefin Unit located on Pars Special Economic Energy Zone (P.S.E.E.Z). Considering the importance of the petrochemical unit, its environmental assessment seems necessary to identify and reduce potential hazards. For this purpose, after determining the scope of the study area, identification and measurement of the environmental parameters, environmental risk assessment of the unit was carried out using Environment Failure Mode and Effect Analysis (EFMEA). Using the noted method, sources causing environmental risks were identified, rated and prioritized. Beside, the impacts of the environmental aspects derived from the unit activities as well as their consequences were also analyzed. Furthermore, the identified impacts were prioritized based on Risk Priority Number (RPN) and severity level of the consequences imposed on the affected environment. After performing statistical calculations, it was found that the environmental aspects owing the risk priority number higher than 15 have a high level of risk. Results obtained from Low Density Polyethylene Unit revealed that the highest risk belongs to the emergency vent system with risk priority number equal to 48. It is occurred due to imperfect performance of the reactor safety system leading to the emissions of ethylene gas, particles, and radioactive steam as well as air and noise pollutions. Results derived from secondary assessment of the environmental aspects, through difference in calculated RPN and activities risk levels showed that employing modern methods and risk assessment are have remarkably reduced the severity of risk and consequently detracted the damages and losses incurred on the environment.