Emissions of nitrogenous pollutants in chemical looping gasification of high nitrogen wood waste using a K-modified copper slag oxygen carrier

This study uses K-modified copper slag as an oxygen carrier (OC) candidate to examine the characteristics of Chemical Looping Gasification (CLG) of high nitrogen wood waste (HNWW) and investigated the emissions of nitrogenous pollutants (NH3/HCN). K modification significantly improves the reactivity of original copper slag because some new species were generated. The calcined copper slag loaded with 10 mass% K (10 K-CS) has relatively higher performance, thus, it was selected as an OC in the CLG of HNWW. The presence of 10 K-CS significantly promotes the conversion of HNWW, especially the char conversion. A suitable HNWW to 10 K-CS mass ratio was determined as 3:7. The OC not only promotes the release of nitrogen (N) in HNWW and oxidizes the reducing nitrogenous-pollutants, thus, the generated NH3 and HCN content decrease significantly. Compared with HNWW pyrolysis, the NH3 and HCN content decrease by 78.86% and 46.20%, respectively, at the mass ratio of HNWW to 10 K-CS of 1:10. High temperature promotes the non-gas-phase nitrogen in char/tar to be converted into the nitrogenous pollutants. A long residence time facilitates the oxidization of nitrogenous pollutants. The introduction of steam promotes the release of nitrogenous pollutants, especially NH3.

Automated summary

This study investigates the characteristics of Chemical Looping Gasification of high nitrogen wood waste (HNWW) using K-modified copper slag as an oxygen carrier (OC) candidate, and examines the emissions of nitrogenous pollutants. The findings show that 10% mass-loaded K-modified copper slag has higher reactivity and can significantly reduce the content of nitrogenous pollutants in HNWW.