Fire on an alkaline electrolyser

A fire broke out on the insulating plastic elements of an alkaline electrolyser in a unit of a chemical plant. The shift saw the smoke from the control room.
The first action was to drain the potash into a tank provided for this purpose and to shut down the electrolyser. The on-call electrician interrupted the electricity.
The safety technician brought the fire under control in less than 10 minutes using CO2 extinguishers. After approximately six hours, the unit was restarted.

The INITIATING CAUSE of the event was potash leak on the electrolyser block that induced an electric arc between the electric block and the bus bar. This ignition caused a rise in temperature followed by the outbreak of fire.
ROOT CAUSE unknown.

Alkaline electrolyser

The following steps were taken:
• The potash was drained into a tank provided for this purpose and to shut down the electrolyser.
• The on-call electrician interrupted the electricity.
• A no-go area is defined with ribbons and the metallic curtain are opened to provide natural ventilation.
• The technician controls the electrolyser using a thermal camera.
• The safety technician brought the fire under control in less than 10 minutes using CO2 extinguishers.
• After approximately six hours, the unit is restarted.

Following the event, the operator implemented the following actions:
• Increase the frequency of predictive and preventive maintenance: preventive visit to each electrolyser with cleaning or repair if necessary;
• Add to the return of experience the occurrence of this event;
• Increase operator awareness.