Assessment of Flammulina velutipes residue as potential fuels for co-combustion with pine sawdust from characteristics of combustion process, flue gases and ashes

Abstract Large quantities of Flammulina velutipes residue needs to be disposed of in a scientific and timely manner. In this work experiments were carried about thermogravimetry, flue gas detection and ash formation to assess the potential of this residue as fuels for co-combustion with pine sawdust. For all the studied feedstocks, curves of combustion displayed the similar patterns and trends under impacts of elevated heating rates and residue ratios, laying the foundation of co-combustion. Synergistic effects between blend components occurred and lowered the ignition temperature and combustion intensity, resulting in the relatively smaller apparent activation energy fluctuating between 22.95 and 48.51 kJ·mol-1. Higher ash and lower volatile contents in residue leaded to the inferior co-combustion characteristics reflected by the decreased combustion indices. The maximum NOX emission reached 106.60 mg·Nm-3 with 40 wt. % residue in blends and could meet the most stringent standard requirements. Ashes presented a high or medium tendency of fouling and slagging, as one main barrier for thermal conversion. Risks of self-ignition indicated the medium or low chance of spontaneous combustion, benefitting to the logistics. On the whole, Flammulina velutipes residue can be considered a suitable addition to pine sawdust in co-combustion.