Process for subjecting a material to a chemical reaction or to a physical change in a fluidised bed, and the modified fluidised bed used.

摘要

A process (and apparatus therefor) for carrying out thermally initiated chemical reactions or physical changes by heating a particular substrate in a fluidised bed having hotter zone(s) and cooler zone(s) between which the fluidised particles circulate, the dwell time in the hotter zone(s) being sufficiently short so as to prevent the particles undergoing an undesirable thermal transformation, and/or the dwell time in the cooler zone(s) being sufficiently long to allow chemical reaction and/or physical changes to take place which prevent undesirable thermal transformations occurring in the hotter zone(s). The fluidised bed process is applicable, for example, to the polymerisation of a low molecular weight poly(ethylene terephthalate) and to a process for the preparation of poly (ethylene terephthalate) from a terephthalic acid and ethylene oxide.