Multizone downcomer for slurry hydrocarbon synthesis process

A vessel comprising:

• an outer shell containing a three phase slurry,
• a feed inlet entering said vessel,
• an outlet from said vessel,
• at least one downcomer immersed in said slurry comprising at least one inner gas-and-solids-disengaging zone and at least one outer gas-and-solids-disengaging zone, whereby said outer zone peripherally surrounds said inner zone, and said inner and outer zones being in fluid communication,
• said outer zone comprising the area between an outer wall and an inner wall,
• said inner zone comprising the area within said inner wall,
• each said zone further comprising a zone bottoms,
• each said zone bottoms containing at least one orifice within said zone bottoms opening into at least one zone-respective hollow downcomer conduit which extends downward from said zone bottoms,
• whereby said downcomer is positioned such that said slurry will flow over said outer zone's said outer wall into said outer zone and said inner wall functions as a weir means for a gas-and-solids-reduced slurry present in said outer zone to flow over said inner wall into said inner zone,
• whereby said orifice permits slurry in said outer and inner zones to flow out of said outer and inner zones and through said downcomer conduits into said slurry.