Method and apparatus for withdrawal of small catalyst particles in FCC systems

摘要

Disclosed is a method of and apparatus for reducing the level of extremely small catalyst particles ("fines") in an FCC system by temporarily retaining particles separated from the secondary cyclone separator in a reactor vessel or catalyst regenerator. These particles can be intermittently withdrawn from the temporary retaining area in order to achieve particle flow at a low volume rate, which takes them out of the active catalyst inventory within the reactor/regenerator system. The intermittent withdrawing of catalyst "fines"]reduces the particulate contamination both in flue gas exhausted to the atmosphere from the catalyst regenreator and in the main column bottom (MCB) produces from the fractionation stage. Preferred embodiments include intermittent withdrawal of "fines" from either the regenerator or the reactor vessels and the secondary cyclones contained in each of these vessels.