Patent ID: 6902593
Filing Date: 2005-06-07
Classification: B01D,B01J,B04C

Abstract:
1. An external separator housing a plurality of cyclones in an external separator vessel useful in a fluidized catalytic cracking process wherein a hydrocarbon feed is catalytically cracked by contact with a regenerated cracking catalyst in a cracking reactor to produce lighter products and spent catalyst, spent catalyst is regenerated in a catalyst regenerator having one or more separators for recovery of catalyst and fines from flue gas, to produce regenerated catalyst that is recycled to the cracking reactor and regenerator flue gas containing catalyst fines, wherein the external separator removes at least a portion of the fines from the regenerator flue gas stream, wherein the cyclones comprise: a cyclone body having a length, a longitudinal axis, an inlet end and an outlet end; a flue gas inlet in fluid communication with the inlet end of the cyclone body; a gas outlet tube in the inlet end of the cyclone body for withdrawing gas with a reduced fines content; a longitudinal axis of the gas outlet tube aligned with the longitudinal axis of the cyclone body; a solids outlet in the outlet end of the cyclone body for discharge of fines and a minor amount of gas into a catch chamber in a lower portion of the external separator vessel; a gas reflux opening in the outlet end of the cyclone body for recycling a portion of the gas discharged with the solids through the solids outlet from the catch chamber back into the cyclone body; wherein the gas reflux opening is isolated from the flue gas inlet at the inlet end of the cyclone body; a shield extending downwardly from the outlet end of the cyclone body around the gas reflux opening; wherein the shield inhibits solids from being entrained in the gas recycled through the gas reflux opening into the cyclone body.