An Explosion in an Electrolyzer for the Production of Chlorine
An explosion occurred in a electrolyzer cell, the vent blew up and caused a pipe rupture on the low pressure chlorine pipeline. The event occurred when two operators were improving the tightness of the diaphragm by injecting a suspension of silica and magnesium chloride or glass fiber. A reaction between hydrogen and chlorine in the cell vapor space was responsible for the explosion. The migration of hydrogen towards the chlorine, producing an explosive mix, was due to excess pressure in the cathodic compartment.
Event Date
September 5, 2005
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes (Select all applicable options):
Cause Comments
The diaphragm separating chlorine and hydrogen compartment was not of the required quality. It was cured at 275C instead of 355C due to a failure of the regulation system of the oven. It led to a faster aging of the diaphragm.Explosive mixture of hydrogen and chlorine may also be due to : - a wrong positioning of the injection pipe of soda leading to a too high level of soda in the compartment- clogging of the soda exit pipe- clogging of the hydrogen exit pipe
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
Production of chlorine by electrolysis
Storage/Process Medium
Location Type
Location description
Industrial Area
Operational Condition
Pre-event Summary
During routine controls a malfunction was observed at the level of the diaphragm..The accident occurred when proceeding to a cell vaccination procedure, consisting in improving the seal of the orifice plate (diaphragm) separating chlorine and hydrogen. This is achieved by injecting suspended silica and magnesium chloride or glass fibers
Number of Injured Persons
2
Number of Fatalities
3
Currency
Lessons Learned
The remedial measures adopted were:1) replacing those cells whose diaphragms had been produced under the same temperature conditions; 2) clarifying intervention guidelines relative to cell vaccination; 3) modifying hydrogen outlet pipes to facilitate controls and cleaning, thereby limiting the risk of plugging.
Emergency Action
The production unit is stopped
Release Type
Release Substance
Release Amount (kg)
3.00
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Source Category
References
Event no. 30637 of the French database ARIA (accessed December 2020)