Drum Explosion due to use of Common Vent

The Incident

A drum of waste acetone exploded during the night

The Investigation

A vessel was used to destroy unwanted thionyl chloride, following the safe destruction, the vessel was boiled out with water and then acetone, this acetone was drummed up as waste for disposal. GCMS of the remains showed the presence of aldol products as well as brominated species. The vessel used was connected to a common vent system to a scrubber, which was used to scrub acids. Adiabatic calorimetry showed that a system of acetone / acetic acid / hydrobromic acid will react exothermically, with the onset dependant on the HBr concentration.

Lessons

It is essential with a common vent system to ensure that incompatible materials cannot be sucked back into the wrong reactor. If imcompatibles are present then either they must be kept separate or ensure there is a good enough flow of inerting gas to prevent a suck back of vapours.