Fire at a electrolyser in a chemical plant

The fire started in a electrolysis cell. The fire originated from a hydrogen leak in the hydrogen over pressure control system of the cell and an unidentified ignition source. The ARIA report (sew references) calls this control system a "hydrogen guard".

The hydrogen leak comes from a lack of water in the guard due to the lack of filling of the guards by the operators and their flushing.

The flushing of the hydrogen through the guard was caused by the rise in pressure of the hydrogen line due to the activation of the chlorine burner. This one had detected a drop in hydrogen pressure probably due to pressure losses due to frost-related blockages. In addition, operators had not performed the filling of the water sear in the hydrogen guard because of to the imminent shutdown of electrolysis.
They were also busy managing smokes on several cells. There were no clear instructions to prioritize level verification in the hydrogen water sear.

electrolyer, hydrogen guards

The ARIA report does not directly lesson learnt elements.
Nevertheless, it should be investigated if it is possible to provide efficient passive barriers in case of active barriers deactivation. Also procedures (control) and their priority should be reviewed.