ETHYLENE FRACTIONATOR AUTO-REFRIGERATION INCIDENTCHEVRON PHILLIPS CHEMICAL ETHYLENE UNIT 1544

摘要

Auto-refrigeration of carbon-steel equipment during abnormal events is an ongoing concern inethylene units. In late 2002, while changing out a power supply on the electronic governor forthe propylene refrigeration compressor turbine drive at Chevron Phillips Chemical’s Port ArthurEthylene Unit, the turbine tripped resulting in loss of refrigeration to the ethylene fractionatoroverhead condensers. As the tower warmed up and the pressure increased, the pressurecontrolled flare dump valves and the pressure relief valves opened to the flare system. One ofthe pressure relief valves failed to close causing the tower to depressure down to 12 psig.This presented a potential brittle fracture hazard for an impact tested carbon steel tower.The paper will review the incident, the response that brought the tower to a safe state, andthe mechanical reliability evaluation performed to ensure the tower was safe to re-pressurizeand start up.