CLC method and plant with recovery of gaseous oxygen produced by an oxygen carrier

A method for combustion of a hydrocarbon feedstock (8) by redox-based chemical looping combustion, wherein a redox active mass in form of particles circulates between an oxidation zone and a reduction zone (R0) operating in a fluidized bed, comprising:

• combustion of said hydrocarbon feedstock (8) through contact with said redox active mass in reduction zone (R0),
• oxidation of said redox active mass from said reduction zone (R0) through contact with an oxidizing gas in said oxidation zone,
• feeding said oxidized redox active mass into at least one sealing device (S1) operating in a dual fluidized bed, positioned downstream from said oxidation zone on a transport line carrying said redox active mass to said reduction zone (R0), said sealing device being supplied with at least one neutral fluidizing gas (4, 19), so as to form at least a first stream (7) comprising at least part of said redox active mass sent to said reduction zone (R0), and a second gaseous stream (6) comprising part of said neutral fluidizing gas (4) and gaseous dioxygen released by said redox active mass,
• mixing said second gaseous stream (6) with part (16) of combustion fumes (15) so as to form a combustion fumes recycle stream (9) sent at least partly, after being successively cooled, compressed and heated, to said reduction zone (R0) for the fluidized bed operation thereof.