INTERNALLY CIRCULATING FLUIDIZED BED AS A REACTION/ REGENERATION SYSTEM FOR CATALYTIC CRACKING

摘要

An internally circulating fluidized bed system has been developed for continuous catalytic cracking and regenerating. This system can be used more generally for several other reaction/ regeneration operations (e.g. alkylation, isomerisation, upgrading of oils from biological sources and biomass pyrolysis). The feed is vaporized on entering the reactor through the feed pipe and then pushes the cracking catalyst upwards in the riser. At the same time the cracking reaction is completed in this reactor zone. The gas-solid-separation is accomplished through a conical particle separator as the catalyst-oil-mixture exits the riser, whereby the product gas leaves the reactor through the top, the coke-loaded catalyst falls in a concentric return flow around the riser to the bottom and is then transported through a siphon into the regeneration zone. In this reactor zone the partially deactivated catalyst is regenerated by burning off the coke layer on its surface and is then pushed into the central riser from the lowest part of the regeneration zone. Important fluid dynamic parameters were determined in an acrylic model at room temperature. Scaling relationships were used as much as possible to apply the results from the acrylic model to the reactor itself. The trials in the-hot cracking unit were carried out with gas oil and FCC-equilibrium catalyst. The degrees of conversion obtained are about 70-90%.