Abstract: In order to improve the capability of system risk management of propane dehydrogenation (PDH) unit, a risk influencing factor model of PDH unit system was established. Hazardous factors were identified by the Preliminary Hazard Analysis (PHA).Unsafe events and risk management objects of the PDH unit were obtainedby using Failure Mode and Effect Analysis (FMEA) method.The set of risk influencing factorsto identifythe risks of fire, explosion and dehydrogenation reaction out-of-control in the reactor andto analyze the cause of the risk andcontrol measures were put forward. This paper summarizedtheriskfactors of thePDH unit system in five dimensions: plant operator, operation equipment, materialitself, plant safety management situation, plant operation environment. The relationship between the safety risk factors of the PDH unit systemwas analyzed bythe Decision Making Trial andEvaluation Laboratory (DEMATEL) algorithm. The results showed that the relationship between 7 causal factors and 13 result factors should be considered in the system safety risk control of PDH unit;the corrosion of the materials had the greatest influenceon the risk of the PDH unitsystem;the safety risk awareness was easily affected by other factors;and education and training playedthe most important role in the PDH unit system.

Key words: propanedehydrogenation unit, security risk factors, failure mode and effect analysis, Decision Making Trial and Evaluation Laboratory algorithm, correlation