Multizone downcomer for slurry hydrocarbon syntheses process

A slury hydrocarbon synthesis proccss for forming hydrocarbons comprising:

• (a) contacting a synthesis gas comprising a mixture of H.sub.2 and CO with a solid, particulate hydrocarbon synthesis catalyst in a slurry body which comprises said catalyst and gas bubbles in a slurry liquid under reaction conditions effective to from said hydrocarbons from said synthesis gas, at least a portion of which are liquid at said reaction conditions and comprise said slurry liquid;
• (b) passing a portion of slurry from said slurry body into a first zone to disengage and remove a portion of said gas bubbles and catalyst to form (i) a gas and catalyst reduced slurry from one portion of slurry in said zone and (ii) a gas reduced and catalyst increased slurry from another portion and returning said gas reduced and catalyst increased slurry back into said slurry body;
• (c) passing said first gas and solids reduced slurry into at least one adjacent zone downstream of said first zone thereby creating at least two adjacent gas disengaging zones to disengage and remove more gas bubbles in each said zone and form successive gas reduced slurries, and
• (d) passing slurry from at least one said zone into a fluid conduit by which it is passed in a desired location.