Fire in a fired heater of an ethylene plant

An explosion of a mixture of hydrogen and hydrocarbons occurred at a fired heater of a refinery.
A mixture of a hydrogen and hydrocarbon mixture was accidentally released into the firebox of a fired heater, where it ignited, creating a large fire at a refinery.
The fired heater that had been offline for approximately 12 hours due to an unplanned compressor shutdown. During the start-up, after the burners were ignited, the process fluid failed to flow in all four passes. This caused the tube wall temperature to reach 1500 F (815 C), exceeding the design limit. The operator turned out two of the 8 burners and reduced the flow throw the first 3 passes, to help the flow in the forth. An inspection team found the tubes gluing red, but thought to hear the flow in the fourth passes, concluding that the flow meter, which was giving no flow, was malfunctioning,
After less than a hour later, a tube in the fourth pass ruptured due to overheating), releasing 1800 kg of a mixture of hydrogen and hydrocarbons into the firebox. The mixture was ignited by the burners producing a large fire.
No injuries, estimated that the property damage from the incident was $10 million.

The INITIATING CAUSE was due to lack of flow in one of the fired heater passes, which caused the loss of confinement of one of the tube due to over-heating.
The IGNITION was provide by the burners flames
CONTRIBUTION and ROOT CAUSES were:
(i) the correct start-up procedure was not followed. This procedure required maintaining a steady flow through all four tube-passes before lighting the burners.
(ii) the fired heater lacked engineered safeguards to prevent the burners from being lit before establishing flow in each of the four passes.

heater tube, fire box, fired heater

The fired heater that had been offline for approximately 12 hours due to an unplanned compressor shutdown.

An automated safeguard would have prevented the burners from being ignited before the minimum flow was established through each of the four tube passes contributed to the incident. The fact that such a system was not present hint at a lack of realistic accidental scenarios supporting a correct risk assessment.

In response to the incident, the company modified its automated burner controls to ensure that the flow rate through every pass exceeded a predetermined minimum flow rate before operators could ignite a burner.