Fire Incidents at Ethylene Oxide Reactors in Ethylene Glycol Plant

PresentationIn September 26, 2012 NYPC Mailiao Ethylene Glycol (EG-4) plant reported a fire incident on the spool piece flanges of inlet pipeline of both two Ethylene Oxide (EO) reactors, R-1/R-2, which were founded 43 minutes later after Recycle Compressor tripped. 1. The deformed bolts were founded on the Inlet pipeline spool piece flanges of both R-1 and R-2 reactors, which were caused by unexpected extra high temperature, leaded to the leakage of ethylene mixed gas and spontaneous combustion. 2. The insufficient and invalidated emergency vent, following the Recycle Compressor trip, triggered the abnormal oxidation reaction of ethylene/oxygen mixed gas at the front-end of both two reactors, 180 seconds after compressor trip, which gave rise to the extra high temperature in the reactor inlet pipeline and reactor dome. 3. The 6 inches valve of emergency vent kept open 90 seconds following the compressor trip, but the pressure drop was only 1.5 Bar, less than safety criterion 3.0 Bar. It indicated an insufficient vent quantity and created a possible pocket of gas of explosive concentration. 4. Recycle Compressor was tripped by low oil pressure while its affiliate main and auxiliary oil pumps losing its 380V power supply at the same time. 5. The ACB(air circuit breaker) of 380V power panel, MCC-100/200, was tripped by ground fault relay protection resulted in stopping of power supply for all its distributed seventeen equipment, which included not only the main and auxiliary oil pumps of Recycle Compressor but also the air cooler fan motors of CO2 stripper condenser. 6. The stator winding damage of air cooler fan motor caused an unexpected trip of the upstream ACB of 380V power distribution panel for its improper setting of ground fault relay protection. Tripping the MCCB(molded case circuit breaker) of motor itself to be treated a satisfactory way for protection of power supply system