Explosion from Flammable Gases from a De-Hydrogenation Reactor
An explosion occurred in a water skim tank associated with an ethyl benzene dehydrogenation reactor system. The reaction mixture from the reactors containing styrene, ethylbenzene, benzene, toluene, hydrogen, C02 and steam. Following separation in a "separator", the water layer containing entrained hydrocarbons and styrene polymers, passes to the skin tank where future separation of the two phases taken place. An emergency plant shutdown, due to partial electric power failure, was carried out and the explosion occurred about one hour later.
Event Date
November 17, 1980
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
It was concluded that the original cause was the fall of the water level in the skim tank during the shut down. This created a vacuum and air was drawn in via an atmospheric vent, which formed a flammable mixture with the hydrocarbons and this was probably ignited frictional over heating of the neck bush on the tank's submerged pump shaft.. This could in fact, have happened at any time, since the tank is not nitrogen purged.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
pipe
Storage/Process Medium
Location Type
Location description
Unknown
Operational Condition
Lessons Learned
Lessons Learned
The main recommendations were of technical nature, to prevent the creation of flammable atmospheres: 1. Blanketing with insert gas2. Preventing air ingress3. Replacing of the submerged pump by an external pump4. Installation of a panel mounted low skim tank level alarm5. Automatic closure of the tank level control valve on air failure
Event Nature
Emergency Action
Unknown
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description extracted from the UK database ICHEME in PDF.
The ICHEME database is no longer available for purchase, but data can be download as PDF for free.
https://www.icheme.org/knowledge/safety-centre/resources/accident-data/
(accessed October 2020)