Abstract: A process and apparatus for rapid stripping of fluid cracking catalyst is disclosed. A series of concentric annular beds provide rapid initial removal of hydrocarbons from the interstices of the catalyst particles. Successive stages of stripping allow time for hydrocarbon diffusion from catalyst's pores while maintaining low hydrocarbon partial pressure. Residence times increase as the catalyst passes to the different catalyst beds.

Abstract: A process for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with a solution containing solubilized iron chelates of a specified organic acid or acids. The contacting is carried out in first and second contacting zones, the first being a gas-solution mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution without plugging due to deposition of sulfur.

Abstract: A process and apparatus for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with an aqueous reactant solution containing solubilized iron chelates. The contacting is carried out in first and second contacting zones, the first being a continuous liquid phase mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution by producing an upwardly flowing continuous liquid phase mixture comprising sour gas dispersed in the aqueous reactant solution.

Abstract: Froth or foam sulfur particle accumulation during the recovery of sulfur particles from a zone containing regenerated redox solution is reduced by agitating and removing the sulfur slurry in a plurality of streams, including at least one stream at a short distance from the top of the solution in the zone and at least one stream from the bottom of the zone and optionally recombining the streams after removal.

Abstract: A process for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with a solution containing solubilized iron chelates of nitrilotriacetic acid. The contacting is carried out in first and second contacting zones, the first being a gas-solution mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution without plugging due to deposition of sulfur.

Abstract: A process for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with a solution containing solubilized iron chelates of a specified organic acid or acids. The contacting is carried out in first and second contacting zones, the first being a gas-solution mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution without plugging due to deposition of sulfur.