Production of low-tar producer gas from air gasification of mixed plastic waste in a two-stage gasifier using olivine combined with activated carbon

• Stable gasification was conducted over 3 h in a two-stage gasifier.
• Strong tar removal was achieved with the combination of activated carbon and olivine.
• Only two-stage gasifier with additives and condenser were enough for tar removal.
• About 98% of tar removal efficiency was achieved in the work.

A fraction of mixed plastic waste was gasified using olivine as a bed material and activated carbon as a tar-cracking additive in a two-stage gasifier. The effects of the amount of activated carbon, the use of an activated carbon filter, and the removal of an EP (electrostatic precipitator) from the process on the gas composition and tar amount generated were investigated. The effects of the ER (equivalence ratio), the type of distributor, the use of steam and the use of a wire mesh basket for activated carbon on the coke removal were also examined. As a result, H2 concentrations of around 30 vol% were obtained with 1500 g of activated carbon. The tar removal efficiency was maximized at about 98% with the application of 1500 g of activated carbon and steam. The LHVs (lower heating values) of the producer gases obtained with the two additives at ERs of about 0.31 were in the range of 5.3–6.2 MJ/Nm3.