RELEASE OF HYDROGEN CHLORIDE
During operations to clear a blockage in a reactor run-off line there was a spill of part of the reactor contents. The batch contained anhydrous aluminium chloride. On contact with water in a nearby effluent sump some HCI was released. The leak was stopped by applying vacuum to the reactor and then re-fitting the blank which had been removed for clearance of the blockage. The bottom outlet valve (BOV) on the reactor, a 'mushroom' valve, must have been passing although no fault was found subsequently.
Actions to prevent recurrence included:
- The installation of a second valve immediately downstream of the BOV
- Spading to be done before attempting to clear blockages
- Secondary containment around the reactor so as to prevent a spill running into the effluent sump.
An alternative to 'mushroom' valves, which will cope with suspended solids in the reactor, is being sought.