Gas Fired Oven Explosion

摘要

A natural gas fired industrial oven exploded during an attempted restart a few hours after a coldstart. The explosion was caused by accumulation of natural gas during the hours preceding therestart. The oven had a fully-automated control system, and the start, shutdown, and restart werecontrolled by process controls and a flame safeguard system. A malfunction of the flamedetector allowed the automated controls to complete the start sequence and establish normaloperating status without a flame present in the burner. The UV flame sensor gave a falsepositive signal, which allowed unburned natural gas to enter the oven. The investigationexplored the cause of the incident and the failure modes of the flame detector.