Grey relational analysis of N₂O emission from oil shale-fired circulating fluidized bed

This study aims to identify key operating variables affecting N ₂O emission from oil shale-fired circulating fluidized bed (CFB). These operating variables include bed temperature, excess air factor, particle size, secondary air ratio, Ca/S ratio, circulation rate and bed material height. Using an oil shale-fired CFB pilot setup composed of a quartz tube and heated by an electric heater, the experiments of N₂O emission were carried out with oil shale test samples obtained from Huadian, China. Grey relational method was used to treat the experimental data. Calculation results indicate that bed temperature is a variable most closely related to changes in N ₂O emission; the effects of secondary air ratio and circulation rate are negligible. The operating variables sequenced in order of decreasing effect are bed temperature, excess air factor, Ca/S ratio, particle size, bed material height, secondary air ratio, circulation rate. The experimental results and grey relational analysis can provide reference data for design of oil shale-fired CFB furnaces.