Evaluation of a Failure in a Chlorine Production Facility

A process upset at a chlorine production facility resulted in a release that forced the partial evacuation of a nearby town. Investigations revealed that the events commenced with the failure of a shell and tube heat exchanger (liquefier) used to condense chlorine gas. Post-incident inspections revealed a cloth at the liquefier coolant inlet that accelerated the flow in that region, causing certain tubes to be breached. As a result, the water-based brine liquefier coolant was entrained in the chlorine process stream, forming a highly acidic oxidizing mixture. This corrosive mixture then flowed to the chlorine storage tanks destroying an elbow in the tank inlet piping and rendering the tank shut-off tank valve ineffective, thus allowing chlorine to vent into the atmosphere. This paper discusses the multi-disciplinary approach used to investigate this incident. In particular, this paper discusses the detailed physical inspections performed, the finite element analyses used to determine the flow conditions, and the corrosion testing conducted to evaluate the failure.