http://www.brighthub.com/engineering/mechanical/articles/59525.aspx
Safety-smelt-water explosions
One of the main hazards in operation of recovery boilers is the smelt-water explosion. This can happen if even a small amount of water is mixed with the solids in high temperature. Smelt-water explosion is purely a physical phenomenon. The smelt water explosion phenomena have been studied by Grace [14]. By 1980 there were about 700 recovery boilers in the world [8]. The liquid - liquid type explosion mechanism has been established as one of the main causes of recovery boiler explosions. Source-Wikipedia
Special thanks to Dr V T Sathyanathan for sharing the "Smelt Water Explosion in Chemical Recovery Boiler.," article
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Recovery boiler