System for transporting particulate solids from high temperature to low

Abstract

Fluidizable particulate solids are removed from a first zone operating at a relatively higher temperature and pressure to a second zone or collector operating or maintained at a lower temperature and pressure by an improved drain or particle removal system. The improved system includes moving the particles from the first zone downwardly within a substantially vertical inlet conduit or leg into the lower regions of a first chamber and upwardly through that chamber under fluidized particle transport conditions energized by a fluidizing media provided in the chamber. The particles move to a second chamber by overflowing a weir separating the first and second chambers and are mixed with cooler particles which extract heat within the second chamber under fluidized particle transport conditions energized by a second fluidizing gas source which further transports the particles to the collector or second zone. Heat is removed from the second chamber by indirect heat exchange. The volume of fluidizing gas for the second chamber is much larger than that for the first chamber and provides for particle flow rate control in combination with a flow restriction. Particle flow is interrupted by stopping the particle flow out of, and the gas flow into, the second chamber while maintaining fluidizing gas flow into the first chamber and the inlet leg. The system is particularly suited to draining unreacted alumina from a chlorination reactor for producing gaseous aluminum chloride from particulate alumina.