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To relieve the stress of sewage sludge (SS) disposal and effectively increase the use of renewable energy, a novel renewable-energy microgrid system (REMS) was developed, specifically designed to integrate a wind power plant (WPP) with energy storage and the SS pyrolysis process for heat and power generation. Based on a lab-scale pyrolysis experiment and 7-day numerical analysis, we studied the energy-recycling potential of SS and simulated the operational behaviours of REMS. According to the results, the calorific values of the pyrolytic gaseous and liquid products were better than those of the raw material, at 16.19 and 33.53 MJ/kg, respectively. The proposed REMS performed well in power supply and energy utilization with a design performance index of 99.23 when the WPP capacity was 200 MWe and the initial wind-energy curtailment rate was 30%. It indicates that by converting SS into flammable gas, condensable liquid and carbon-rich solid residue, curtailed wind energy could be saved and the synergy between wind power and the SS pyrolysis process enabled the proposed microgrid system to effectively utilize renewable energy and provide reliable on-demand power service. The REMS installed with a 155-MWe WPP achieved the optimal design in system performance, environmental benefit and construction cost under the initial wind-curtailment rate of 34.12%. The design scheme makes REMS capable of satisfying the 15.10-GWh power demand of end users and the 1700-t/day SS disposal need, and the curtailed wind energy could be reduced to zero. [ABSTRACT FROM AUTHOR]

The interaction between flue gas and ash causes the redistribution of heavy metals and affect their emission characteristics. In this study, a double-layer fixed-bed reactor was used to investigate the effect of this interaction on Pb distribution at 800–1000 °C. Obvious gaseous Pb adsorption by ash just occurred in the case of high-Pb flue gas and less ash melting. In other cases, significant Pb release from ash occurred under the action of the high-temperature flue gas. The occurrences of Pb in ash was found to be thermally stable. Ash melting is the main reason for the Pb release. Gaseous Na in the combustion flue gas and reducing components in the pyrolysis flue gas promote the Pb release via promoting the ash melting. H 2 S and HCl in the pyrolysis flue gas also promote the Pb release by forming PbS and PbCl 2 , which are more volatile. [Display omitted] • The interaction between high-temperature flue gas and ash redistributes Pb. • Ash melting causes the significant release of Pb from ash at high temperatures. • Gaseous Na and reducing components in flue gas promote ash melting and Pb release. • H 2 S/HCl in flue gas also promotes Pb release by forming volatile PbS/PbCl 2. [ABSTRACT FROM AUTHOR]