A reburning process using sewage sludge-derived syngas

The motivation for this work was to define the reburning potential of sewage sludge (SS) gasification gas (syngas). A numerical simulation of the co-combustion process of syngas in a hard coal-fired boiler was made. All calculations were performed using the Chemkin program and a plug-flow reactor model was used. The calculations were modelled using the GRI-Mech 3.0 mechanism. The highest conversions for nitric oxide (NO) were obtained at temperatures of approximately 1000 K to 1200 K. The highest reduction efficiency was achieved when the molar flow-ratio of the syngas was 15 %. The combustion of hard coal with sewage sludge-derived syngas reduces NO emissions and the amount of coal needed to produce electricity and heat. Furthermore, advanced reburning, a more complex process, achieved an efficiency of up to 80 %. Calculations show that the syngas thus analysed can provide better results.