Effect of precalciner collaborative disposal of RDF and bituminous coal on the generation and transformation of NO_x and SO₂

It is one of the current development trends to utilize cement kilns to dispose of refuse derived fuel. However, there is a problem of unstable pollutant discharge in the actual disposal process. This paper takes refuse derived fuel disposed via a cement plant in China and two kinds of standard bituminous coal as the research object and conducts experiments with a high-tempera­ture tubular furnace. The release characteristics of NO_x and SO₂ from two kinds of refuse derived fuel at 500~900 °C and two kinds of bituminous coal at 700~1000 °C were studied. The experimental results showed that the peak concentration of NO_x was more affected by temperature at low temperature (500~600 °C), and the peak concentration of NO_x refuse derived fuel was less affected by temperature at high temperature (700~900 °C). In the process of bituminous coal combustion at various temperatures, the first peak value of NO_x was less affected by temperature, and the second peak value was more affected by temperature. In the combustion process of two kinds of refuse derived fuel, the conversion rate of NO_x showed an “inverted V” shape with the change of combustion temperature, while the conversion rate of SO₂ showed a “positive V” shape with the change of combustion temperature. Both NO_x and SO₂ played a mutually inhibitory role in the formation process. At 1000 °C, the combustion efficiency of bituminous coal was low, and a few drops of substance containing N in bituminous coal would be released with the complete combustion of C, while a large amount of substances containing S in bituminous coal would be released with the complete combustion of C.