Mechanical pretreatment of typical agricultural biomass on shape characterization and NO emissions during combustion

The impact of mechanical pretreatment of corn straw (CS), pea straw (PS), and wheat straw (WS), on shape characterization and NO emissions during combustion were investigated in this research. Particle size ranges were obtained and characterized their shape factors using Image J correction. The thermal properties and NO emissions of the different-sized particles were investigated by TG-MS and fixed-bed reactor. Compared with CS and PS, WS is more likely to break into smaller particles due to its moderate strength. Amine-N completely disappeared after pyrolysis, whereas pyrrolic-N and pyridinic-N were the main N functionalities in char-N. During the volatile burning stage, the maximum peak of NO concentration was 270, 354 and 311 ppm for CS, PS and WS, respectively. NO was detected at a steady level during the semicoke combustion stage, and the duration increased with particle size. The NO concentration decreased sharply in a short duration during the fixed carbon combustion stage.