Molten-salt-heated indirect screw-type thermal processor

Abstract

A body of heat transfer fluid circulates in a first loop through an indirect screw-type thermal processor, a rundown tank, a pump, a heater and a fill tank, continuously heating the processor. With the pump operating, a first vertical distance between the fill tank bottom and the processor under the influence of gravity sets a minimum fluid pressure at the processor; a stem pipe opening in the fill tank at a second vertical distance above the processor sets a maximum pressure. With the pump inactive, the entire body of fluid passively drains to the rundown tank. Supplying the fluid may entail melting a salt, hydrating a salt, or both; such may be done in the rundown tank before circulation through the processor begins. A hydrated salt may be circulated, then heated and dehydrated, to gradually warm the processor. A dehydrated salt may be rehydrated and then stored; this may be done in the rundown tank after ceasing circulation through the processor. Also described: misting hydration and variable-speed-pump pressure regulation.