Assessment of citrus wastes gasification through a fluidized bed reactor: experimental analysis for integration in an existing citrus juice industry

The aim of this work is to assess the integration of citrus residues gasification in a Sicilian medium size enterprise, which processes about 85,000 t/year of fresh fruit. In this work, gasification tests were performed in a bench-scale fluidized bed reactor working with both air and air-steam mixtures as gasification mediums. The gasification experiments were carried out at 700, 750, and 850 °C, and at different steam to biomass ratios (0 - 1.25). Thus, evaluations on syngas composition and gasification efficiencies were carried out. According to the experimental results, the highest net cold gas efficiency (0.71) was achieved at 850°C and S/B =0.5. After evaluating the gasification efficiencies of citrus peels, a combined heat and power (CHP) unit, using a reciprocating engine, was selected in order to simulate the combination of the gasification unit with an internal combustion engine (ICE). The results showed that the proposed system allows to produce about 8,256 MWhe/year and 10,224 MWht/year as electrical and thermal output, respectively, by using two CHP units of 516 kWe, and consuming about 7112 t/year of dry citrus peel (10%wt moisture). The thermal power output produced by CHP system may be used for drying the fresh citrus peels up to the desired water content, being this step the most energy demanding step.