In an FCC apparatus in which swirl arms are used to discharge gas and catalyst from a riser, the swirling movement of the catalyst particles is inhibited while impeding the catalyst particles and gaseous products from exiting the disengaging chamber and entering a reactor annulus. The catalyst particles and gaseous products pass through a tunnel comprising a vertical wall to enter the reactor annulus. The vertical wall presents a face that is opposed to the angular direction in which the catalyst particles and gaseous products swirl.
A baffle may be located at the intersection between the reactor annulus and the disengaging chamber to deflect catalyst laterally in a stripping section after exiting the reactor annulus. The baffle may be equipped with openings to fluidize the large proportion of catalyst passing over this region to effectively pre-strip this catalyst before it enters a stripping section.