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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

HEAT EXPLOSION IN FISCHER−TROPSCH CATALYTIC GRANULE WITH LOCALIZED COBALT MICROPARTICLES

Get access (open in a dialog) DOI: 10.1615/IHTC16.cat.022368
pages 1493-1500

Sinopsis

The productivity of Fischer-Tropsch reactors is determined by the efficiency of heat and mass transfer processes inside the catalyst granules. To reduce the diffusion resistance the granules base is made of ceramic highly porous material. The porous structure of the granules causes a discrete arrangement of cobalt metallic microparticles whose size can reach a few microns. Cobalt particles are the active centers on which there are synthesis reactions. The distance between these active centers significantly exceeds their characteristic size and the homogeneous model for heat and mass transfer is incorrect. In our paper a mathematical model of heat and mass transfer processes in a porous spherical granule with localized active centers is proposed. The heat of the exothermic synthesis reaction is removed from the surface of the granule by heat transfer into the synthesis gas stream washing the granule. The components of the synthesis gas crosses the granule surface as a result of mass transfer. On the basis of the mean-field approach the values of the temperature and concentration of the synthesis gas components at the active centers inside the granule were determined. In the reactor tube, where the catalyst granules are placed, there is a critical temperature. The excess of the critical temperature leads to a thermal explosion, i.e. a substantial overheating of the active centers. In this case, the surface of the catalyst granule is slightly superheated.