Sulfur oxide and particulate removal system

A catalytic cracking and gas purification system, comprising:

• a catalytic cracker for cracking a hydrocarbon feedstock in the presence of a catalytic cracking catalyst;
• a cracking catalyst regenerator positioned downstream of and communicating with said catalytic cracker for regenerating spent catalytic cracking catalyst and emitting regenerator off-gases containing sulfur oxides and particulates;
• a granular bed filter comprising an elongated, substantially upright, sulfur oxide-capturing and particulate-removing vessel, said vessel positioned downstream and communicating with said cracking catalyst regenerator for substantially filtering said particulates and substantially removing said sulfur oxides from said regenerator off-gases to form substantially purified gases having a substantially lower concentration of sulfur oxides and particulates than said combustion off-gases, said vessel having a roof, a frustoconical bottom portion having flared walls converging generally downwardly, and sidewalls connecting said roof and said bottom portion, said vessel defining a vertical axis and containing a downwardly moving bed of balls comprising sulfur oxide-capturing and particulate-removing material, said vessel having an elongated upright conduit defining a substantially vertical gas inlet extending downwardly through said roof along said vertical axis into said bed for passing said regenerator off-gases into said bed, said vessel having a purified gas outlet line having an intake mouth located above said bed and a frustoconical collection reservoir with flared sidewalls extending below the mouth of said purified gas outlet line, said flared sidewalls diverging generally downwardly from and cooperating with said roof for holding balls comprising regenerated sulfur oxide-capturing and particulate-removing material, said reservoir positioned above said bed and circumferentially surrounding a portion of said upright conduit, and a plurality of chutes extending between and communicating with said reservoir and said bed for feeding said balls comprising said regenerated sulfur oxide-capturing and particulate-removing material from said reservoir to said bed, said chutes including a vertical chute concentrically position about a portion of said conduit below said reservoir and a plurality of substantially symmetrical inclined chutes positioned at an angle of inclination relative to the vertical axis of said vessel in a direction away from said vertical gas inlet;
• said sulfur oxide-capturing and particulate-removing material selected from the group consisting essentially of adsorbers and adsorbers with at least one promoter thereon, said adsorbers substantially comprising an oxide of at least one metal selected from the group consisting of aluminum, bismuth, manganese, yttrium, antimony, tin, a rare earth metal, a Group 1a metal, and a Group 2a metal, and said promoter selected from the group consisting essentially of a rare earth metal, a Group 8 metal, chromium, vanadium, rhenium, and combinations thereof;
• an upright elongated, lift pipe riser spaced laterally from and communicating with said granular bed filter for regenerating spent balls comprising spent sulfur oxide-capturing and particulate-removing material, said lift pipe riser spaced laterally away from said cracking catalyst regenerator, said lift pipe riser having a lower portion and an upper portion, an overhead collection vessel connected to and communicating with said upper portion, and injector means for injecting a gas selected from the group consisting essentially of a reducing gas and an oxygen-containing, combustion-sustaining gas, into said lower portion of said lift pipe riser with a sufficient velocity and pressure to propel and carry said spent material generally upwardly through said lift pipe riser into said overhead collection vessel, said reducing gas selected from the group consisting essentially of hydrogen, ammonium, carbon monoxide, light hydrocarbon gases, and combinations thereof;
• a spent material feedline extending between and connecting said frustoconical bottom portion of said sulfur oxide-capturing and particulate-removing vessel to the bottom portion of said lift pipe riser for feeding said spent balls comprising spent sulfur oxide-capturing and particulate-removing material from said sulfur oxide-capturing and particulate-removing vessel to said life pipe riser;
• a regenerated material feed line extending between and connecting said overhead collection vessel to said roof of said sulfur oxide-capturing and particulate-removing vessel for feeding regenerated balls comprising said regenerated material from said overhead collection vessel to said reservoir of said granular bed filter;
• solid-gas separation means positioned downstream and communicating with said overhead collection vessel of said lift pipe riser for substantially removing particulates from effluent gases emitted from said overhead collection vessel;
• and
• sulfur recovery means positioned downstream and communicating with said solid-gas separation means for recovering elemental sulfur from said effluent gases.