GB646557A - Improvements in or relating to fluidised solid systems - Google Patents

Abstract

<PICT:0646557/III/1> Finely-divided solids are contacted with gases, e.g. in the cata-lytic synthesis of hydrocarbons from CO and H2, by maintaining the catalyst solids in the form of a turbulent fluidized bed, the tendency for the particles of particular sizes to take up definite positions in the bed being negatived by classifying the feed material into two or more fractions according to particle size, and feeding the largest particles to the upper part of the bed and the smallest particles to the lower part of the bed. Intermediate size particles may be fed into the intermediate part of the bed. The return pipe 20 of the gas-solids separator 18 recirculates fines to the bottom of the bed, and this effect is increased by a pipe 19 which brings the inlet of the separator nearer to the surface L30 of the bed and thus ensures that the separator is efficiently loaded with fines. The feed hopper 1 may feed directly through a pipe 3 to an intermediate part of the bed, or it may feed an elutriator 5 which divides the material into two or more fractions, the largest particles being fed to the top of the bed through the pipe 10 and the smallest particles through the pipe 8 to the fluidizing gas-line 15. The material drawn off from the bed may be classified in an elutriator 40, the larger particles being led by a pipe 44 to the upper inlet pipe 10, and some of the fines being delivered by a pipe 42 to the lower inlet-pipe 8.