High quality syngas produced from the co-pyrolysis of wet sewage sludge with sawdust

A method for wet sewage sludge (WS) direct pyrolysis with sawdust (SD) at high temperature for syngas production in a screw moving bed reactor was proposed to solve the issue of direct WS utilization. Meanwhile, the co-pyrolysis characteristics of WS with SD at 900 °C was investigated by TG, Py-GC/MS analysis. The TG analysis showed that significant interactive effects, including inhibition and acceleration occurred when the ratio of SD increased from 20 to 80 wt%. According to Py-GC/MS and co-pyrolysis experiment results, lowest yields of O-containing compounds, aromatic hydrocarbons and the liquid were found under 40 wt% SD addition ratio. Meanwhile, synergetic effects - effects of acceleration as well as moisture on syngas, became more distinct in the same addition ratio. The catalytic in-situ steam, which performed as an oxidizer, promoted steam reforming reaction and secondary cracking of macromolecular. Under the optimum SD addition ratio (40 wt%), the quality of syngas was improved, e.g. H2+CO content increased about 10.19%, H2/CO increased about 0.14, syngas heat produced from 1 kg raw material increased about 4.04 MJ/kg and carbon conversion increased about 12.75%, respectively.