Fluidized bed co-gasification of industrial wastes for flexible end-use of syngas

The search of alternative to fossil fuels for both energy generation and production of organic chemicals (Chum et al. 2001) calls for usage of renewable and waste materials. In this framework, industrial wastes and residual biomass play an important role, as a possible option for substituting oil and natural gas (Consonni et al. 2009). Thermo-chemical processes can be employed for converting the wastes of interest into valuable gaseous or liquid streams. In particular, thermal gasification is the most attractive process due to multiplicity and versatility of syngas applications, such as a chemical feedstock for producing a number of chemical intermediates, a fuel by itself and an intermediate for the production of other fuels or biofuels. As concerns the fuel production, the possibility to match the producer gas output to the synthesis gas specification during the gasification process is a crucial challenge for researchers due to the significant effect that it could have on the overall process economics. In this work an experimental study of waste co-gasification with biomass was conducted using a pre-pilot plant fluidized bed gasifier in order to explore the possibility of producing a syngas with the specifications required by methanol synthesis. The bed was made of either Ni/γ-alumina or pure γ-alumina particles. More specifically a series of experiments were performed to investigate the effect of bed temperature and steam-to-fuel ratio (S/F) on the outlet gas composition, while keeping fixed the equivalence ratio. The results confirm that the fluidized bed co-gasification of selected biomass and wastes (olive husk/PET and olive husk/Tyre pellets) yields a syngas composition suitable for subsequent methanol production. This is true for 0.6 ≤ S/F ≤ 1, the optimum temperature being about 840 °C for both fuels. The presently reported results represent a sound milestone before further optimization work of the process experimental conditions