Investigation on the emission characteristics of NO and SO2 in the sewage sludge char co-combustion with biomass.

Abstract

The emission of nitrogen oxides (NO_x) and sulfur dioxide (SO₂) during the combustion of fuels remains a critical environmental concern. This work systematically examined the emission characteristics of NO and SO₂ in sewage sludge (SS) char (SC) co-combustion with corn straw (CS) at the different blending ratios and combustion temperatures. The novelty of this work is the detailed investigation of the co-combustion emissions of NO and SO₂, considering various blending ratios of SC and CS and combustion temperatures. This work advances previous research by focusing on the synergistic effects of SC and CS blends, offering cleaner energy conversion by reducing NO_x and SO₂ emissions more effectively than individual combustion of these fuels. The combustion tests were conducted using a tubular furnace system, where the emission concentrations of NO and SO₂ in the flue gas were measured in real-time. The results revealed that as the proportion of CS increased, the NO emissions increased while the SO₂ emissions decreased, demonstrating a clear synergistic effect that reduced emissions compared with the theoretical calculated values. Combustion temperature also significantly influenced the emissions, with higher temperatures leading to an increase in NO emission but a decrease in SO₂ emission in some cases. Overall, this work offers insights into optimizing the co-combustion process of SC and CS for cleaner energy production, contributing to the reduction of combustion-related air pollutants and enhancing the sustainable use of SS and agricultural biomass as renewable energy sources.