Fire at a Chlorine Electrolyzer
Two successive fires broke out in an interval of few minutes in four cells in the electrolysis room of a chlorine production plant. The technicians brought the fire under control using the fire-fighting equipment located nearby. In both cases presence of hydrogen, ignited by a short circuit spark, was responsible for the two accidents. Case (1): the hydrogen leaked when a rubber-plastic pipe was manually disconnected from a hydrogen trap. Despite the fact that that this operation is covered by a specific procedure, it was performed when hydrogen quality was not good enough to be collected. Case (2): the hydrogen leaked when a sleeve failed locally by corrosion.
Event Date
June 26, 2003
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
The two fires have different root causes. In case (1) was a wrong operation (in presence of a formal procedure). In case (2) it was probably a design or inspection shortcoming (corrosion)The immediate cause of the Ignition of the released hydrogen is an electrical spark caused by a short-circuit. Different potential causes of the short-circuit were identified:- the compatibility of insulating material has not been checked- lack of wet-proofing between anode and cathode- not enough distance between anode and hydrogen pipe due to a modification of the connection and a miss-alignment of the cells
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
electrolyzer's cells
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Currency
Lessons Learned
Lessons Learned
The analysis of the accident and the corrective actions retained were presented to the company Committee hygiene, safety and working conditions before operations could resume. These included (a) choice of a better suited insulating material, (b) improving process orifice to reduce the presence of chlorine in the hydrogen and avoid disconnection of the pipe from the trap, (c) improving quality control and supervision by team leader, (d) re-designing hydrogen flanges to space them out from the anode, (e) communicating the lessons learnt from the accident to the staff, (f) improving procedures and guidelines, (g) taking stock of all insulation malfunctions of all cells.
Event Nature
Emergency Action
The two release of hydrogen ignites within a couple of minutes. The fire is extinguished by the operators.
Release Type
Release Substance
Hydrogen Release Concentration (%)
100.00
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
References
Event description in the French database ARIA
https://www.aria.developpement-durable.gouv.fr/accident/25112/
(accessed January 2023)