Process for converting carbonaceous material into low tar synthesis gas

A continuous multi-stage vertically sequenced gasification process for conversion of a solid carbonaceous fuel material into a low tar syngas in a gasifier comprising:

• i) a pyrolysis zone,
• ii) a partial oxidation zone located vertically downstream of the pyrolysis zone, and separated from the pyrolysis zone via a separation member comprising a plurality of upwardly angled vents;
• iii) a reduction zone located vertically downstream of the partial oxidation zone and comprising an angled perforated floor, an openings located centrally relative to the angled perforated floor, and a centrally located deflector;
• the angled perforated floor being sloped downwardly and inwardly toward the opening, wherein the perforated floor is configured, by sizing of perforations therein, to allow passage of a raw syngas therethrough, and to inhibit passage of a raw pyrolysis residue obtainable in the pyrolysis zone, wherein the slope of the angled perforated floor is greater than zero degrees and less than 60 degrees;
• said process comprising the steps of:
• a) feeding the solid carbonaceous fuel material through the upper portion of the pyrolysis zone vertically downwardly towards the lower portion of the pyrolysis zone, while pyrolyzing the solid carbonaceous fuel material into pyrolysis vapours comprising a hydrocarbon material, and the raw pyrolysis residue comprising char and ash;
• b) optionally adding a first oxidant to the lower portion of the pyrolysis zone to achieve a temperature greater than 200° C.;
• c) directing the pyrolysis vapours to the partial oxidation zone, and directing the raw pyrolysis residue downwardly to the reduction zone via the separation member;
• d) adding a second oxidant in the partial oxidation zone to achieve a temperature sufficient to reform the pyrolysis vapours into the raw syngas containing significantly reduced levels of tar;
• e) forming a pyrolysis residue bed having a uniform depth from the raw pyrolysis residue formed in step c) on the floor of the reduction zone;
• f) passing the raw syngas from step d) downwardly through the pyrolysis residue bed formed in step e), and carrying out an endothermic reaction between CO2 and/or H2O in the raw syngas and carbon of the char in the pyrolysis residue bed, while controlling a reduction zone pressure drop, a reduction zone residence time and a reduction zone flow space velocity of the raw syngas during the endothermic reaction to form a substantially tar free enhanced syngas and a decarbonized pyrolysis residue;
• g) passing the substantially tar free enhanced syngas from step f), in upward counter-current flow, to heat the pyrolysis zone and subsequently cool the substantially tar free syngas;
• h) collecting the substantially tar free syngas;
• and
• i) collecting the decarbonized pyrolysis residue from the bottom of the gasifier.