Gasification of pellets produced from blends of biomass wastes and refuse derived fuel char

Refuse derived fuel (RDF) is a highly heterogeneous material that contains carbonaceous components with a good calorific value but also significant moisture and ash contents. The torrefaction process can help to upgrade RDF and obtain a fuel with improved properties for combustion or gasification because the RDF char is easier to grind, more hydrophobic and more homogeneous. The main purpose of this work is to test the gasification of biomass wastes, supplemented with different percentages of an industrial RDF char. RDF produced from non-hazardous industrial waste was carbonized at 300 °C for 30 minutes in a rotary pyrolysis furnace. The RDF char was incorporated in biomass pellets at 5 and 10% fortification levels. The pellets with higher incorporation of RDF char presented higher contents of fixed carbon and lower contents of volatile matter, leading to a slight increase in their high heating value. The reference pellets and the pellets fortified with RDF char were subject to gasification in a 1 kg/h bubbling-fluidized-bed gasifier (BFBG) at different temperatures (800 and 850 ºC) and equivalence ratios (0.25 and 0.30). The results suggest that an increase in the RDF char incorporation is negatively correlated with the producer gas concentration. However, this decrease appears to be negligible, since the values obtained for the absolute yields of CO and H2 were found to be between 0.22-0.40 m ³ /kg and 0.08-0.30 m ³ /kg, respectively. Samples with incorporation of RDF char presented heavy PAHs in their tar extracts (in very low percentages) as well as a significant ash amount in the cyclone, after each run. The RDF char represents an upgrade of a waste material with low commercial value enhancing its physical-chemical properties and enabling its use as a gasification additive at moderate incorporation ratios in order to avoid an excessive increase in ash and tar and a decrease in gas productivity.