Explosion and Fire in a Chemical Plant Producing Aromatic Hydrocarbon
A gaseous mixture of hydrogen (H2), methane (CH4) and ethane (CH3-CH3) at 54 bar was cooled in a heat exchanger upstream of a hydrogen purification system. The accident started with a double explosion followed by a fire.The heater used to regenerate the adsorbent beds of the purification unit had been repaired a few hours earlier, but the automatic heating mode had not been activated upon restart. Therefore, two regeneration cycles had been carried out cold, causing an overload of the adsorber and the fouling of the heat exchanger. The operators detected a pressure problem in the exchanger and shut down the installation; the explosion occurred 40 minutes later. The investigation showed advanced corrosion at the seals and fins of the exchanger due to the condensation of acidic and basic aqueous products in the H2 purification system. The facility had been in operation for 20 years.
Event Date
July 10, 2007
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
According to the ARIA report (see references), the immediate cause was the failing of switching on the automatic heating of the heating of the catalyst bed. The weakening of the line due to corrosion was then the principal cause for the containment failure and of the release. The report however does not explain the relationship between the abnormal operative condition of the catalytic system and loss of containment (probably due a increase of pressure). The failing of guaranteeing the required operative condition seems to suggest an inadequacy of the maintenance procedures and/or lack of training by the workers.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
haromatic hydrocarbons plant, heat exchanger, hydrogen purification unit
Storage/Process Medium
Actual Pressure
54
Location Type
Location description
Industrial Area
Pre-event Summary
The plant was restarted after repairing the catalytic absorbed bed. Its heater however was not switched on as required.
Currency
Lessons Learned
Lessons Learned
The operator reviewed its corrosion monitoring system and considered regular replacement of all or part of the equipment.Although not mentioned by the ARIA report (see references), the failing of switching on the heater of the catalytic bed would probably require a review of the maintenance procedures and their implementation.
Event Nature
Emergency Action
The fire was extinguished in 2 hours by the site security teams and the fire brigade.
Release Type
Release Substance
Release Amount (kg)
1320.00
Release Pressure (bar)
54.00
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Flame Type
Source Category
References
References
Event description in the French database ARIA
https://www.aria.developpement-durable.gouv.fr/accident/43736/
(accessed October 2020)