Thermal runaway

In chemical engineering, thermal runaway is a process by which an exothermic reaction goes out of control, often resulting in explosion.

Thermal runaway is said to occur when the reaction rate increases due to an increase in temperature, causing a further increase in temperature and hence a further increase in the reaction rate. It is a fruitiful source of industrial accidents, most notably the 1984 explosion of a Union Carbide plant in Bhopal, India that produced methyl isocyanate.

Thermal runaway is most often caused by failure of the cooling system for a reactor vessel, with addition of components in the wrong order also being a common cause.

Many chemical production facilities are designed with high-volume emergency venting to limit the extent of injury and property damage when such accidents occur.