Syngas production from olive tree cuttings and olive kernels in a downdraft fixed-bed gasifier

This study presents a laboratory fixed-bed gasification of olive kernels and olive tree cuttings. Gasification took place with air, in a temperature range of 750–950 °C, for various air equivalence ratios (0.14–0.42) and under atmospheric pressure. In each run, the main components of the gas phase were CO, CO2CO2, H2H2 and CH4CH4. Experimental results showed that gasification with air at high temperatures (950 °C) favoured gas yields. Syngas production increased with reactor temperature, while CO2CO2, CH4CH4, light hydrocarbons and tar followed the opposite trend. An increase of the air equivalence ratio decreased syngas production and lowered the product gas heating value, while favouring tar destruction. It was found that gas from olive tree cuttings at 950 °C and with an air equivalence ratio of 0.42 had a higher LHV (9.41MJ/Nm3) in comparison to olive kernels (8.60MJ/Nm3). Olive kernels produced more char with a higher content of fixed carbon (16.39 w/w%) than olive tree cuttings; thus, they might be considered an attractive source for carbonaceous material production.