Research on the Influence of Combustion Methods on NO x Emissions from Co-combustion of Various Tannery Wastes.

Abstract

To further increase combustion efficiency and reduce nitrogen oxide pollution caused by tannery wastes, three raw materials, including tannery sludge, chrome-tanned buffing dust, and chrome shavings, were burned together in a dual-bed model reactor under various conditions. In addition, a thermogravimetric analysis of co-combustion of three tannery wastes was studied in this study, which was conducive to understanding the combustion characteristics and positive effects. The comprehensive combustibility index S, the flammability index Kr, and the stable combustion characteristic index Gb all increased when the tannery sludge was blended with chrome-tanned buffing dust and chrome shavings, indicating that the combustion behavior was improved by co-combustion. For normal combustion, decreasing the gas volume flow and temperature resulted in a decrease in the oxidation of nitrogen compounds, consequently lowering the NOx emission. During air staged combustion, at an appropriate secondary gas ratio of about 10–40%, the NOx reduction would be increased from 10.9 to 19.3%. By increasing the tertiary gas volume flow from 0.2 to 1.1 L/min in decoupling combustion, an average relative NOx reduction efficiency of 47% was attained compared with normal combustion. The results offered a viable technology that resulted in a lower NOx emission and realized the application of decoupling combustion.