Food waste treatment using in situ gasification after pyrolysis to produce hydrogen-rich syngas

In this work, food waste was treated using a novel method of in situ gasification after pyrolysis (IGP) at the same temperature of 700 °C. This was done with the expectation that IGP would result in a higher hydrogen fraction in syngas as opposed to hydrogen fraction from a more conventional approach of overlapping pyrolysis and gasification (OGP). Firstly, both IGP and OGP were carried out at the same steam flow rate (SFR) of 0.625 mL/min and then only IGP was carried out by changing the flow rate from 0.625 to 0.375 mL/min. Comparative data obtained from OGP and IGP was presented for syngas characteristics (syngas yield, syngas composition, hydrogen yield, high heating value (HHV)). The syngas yield from OGP and IGP at the same flow rate of 0.625 mL/min was found to be 1.31 Nm3/kg and 1.48 Nm3/kg, respectively. The hydrogen fraction in syngas from OGP was found to be 54.5%, which increased significantly to 66.7% in syngas from the gasification part of IGP. Consecutively, HHV increased with an increase in hydrogen fraction in syngas from 12.1 to 17.4 MJ/kg. Additionally, the syngas yield obtained from IGP did not change much on changing the SFR to 0.375 mL/min; however, the hydrogen fraction changed to a lower value of 61.04%. Furthermore, performance parameters such as carbon conversion efficiency (CCE) and cold gas efficiency (CGE) are also presented to evaluate the performance of proposed method.