Skikda, Algiers, Jan. 20, 2004 R.A. Hawrelak CBE 497 CBE 317

The Incident A defective, high pressure, steam boiler ruptured in a large refinery in Algiers. High vibrations were heard just before the boiler ruptured. (Two Phase Slug Flow?) The resultant explosion on rupture of the 1500 psig boiler damaged nearby vessels containing flammables. The flammable Loss Of Containment resulted in further fires and explosions.

Results 23 workers were killed. Nine are still missing. 74 were injured. $800,000,000 (U.S.) estimated property damage. We have another “Flixborough” incident.

Observations / Possible Causes A foreman in a storage depot at the complex said he heard “Strange noises and abnormal vibrations coming from a boiler and valves before the main explosion.” This is often symptomatic of two phase flow in the line to the boiler KO drum. Two phase flow in the “Slug Flow” Regime will give you high vibrations.

Flames light the sky after an explosion at Algeria's largest refinery and principal oil exporter in the port city of Skikda, 500 km (310 miles) east of the capital Algiers, early January 20, Rescue workers searched through rubble for missing worker on Tuesday after a huge explosion at its key gas installations killed 23 people on Monday evening, official media said.

Lessons To Be Learned

Lesson To Be Learned High pressure (1500 psig) steam boilers have high potential energy. If opened to atmosphere rapidly, the energy released can be equivalent to many lbs of TNT. Steam boilers, by design, have two phase flow to the KO Drum. On upsets, this flow can get into the “Slug Flow Regime” where high vibrations can cause rupture of the line.

Lessons Learned - Continued If the line rupture, the energy released can damage nearby equipment. If this equipment contains flammables, the LOC can be very hazardous. Early ignition is almost always happens and the resulting fires cause more vessel ruptures and explosions in domino fashion.

End of Presentation Be prepared for exam questions on this type of incident.