Oxy-fuel and air atmosphere combustions of Chinese medicine residues: Performances, mechanisms, flue gas emission, and ash properties

This study aims to quantify the combustion performances, mechanisms, and ash characteristics of Chinese medicine residues (CMR) in the air and oxy-fuel atmospheres. The CMR combustion underwent water loss (<150 degrees C) and the decomposition of the main organic components (150-560 degrees C). The CMR combustion performed better in the air than 8-2/CO2-O-2 atmosphere experimentally, as was also evidenced by the joint optimization based on artificial neural network. The rising oxygen fraction of the three oxy-fuel atmospheres improved the oxy-fuel combustion performance by 76.7%. The air atmosphere led to a higher activation energy at the start (275.15 kJ/mol) and end (520.91 kJ/mol) of the main reaction, while the oxy-fuel atmosphere resulted in a higher activation energy of 400.22 kJ/mol with the conversion degree of 0.7. Its reaction mechanism followed the sequence type (Fn) and changed from F3 to F2 in the 8-2/CO2-O-2 atmosphere and from F2.4 to F2.5 in the air atmosphere and flue gas functional groups included CO2, H2O, C=O, and C-(O)H. The oxy-fuel atmosphere was more prone to slagging than the air atmosphere. The ash in the oxy-fuel atmosphere was easily formed calcium carbonate and calcium hydroxyphosphate. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the combustion performance and mechanism of Chinese medicine residues in different atmospheres. The results showed that Chinese medicine residues performed better in air atmosphere than in oxy-fuel atmosphere, with the increasing oxygen fraction improving oxy-fuel combustion performance. The ash composition in oxy-fuel atmosphere mainly consisted of calcium carbonate and calcium hydroxyphosphate.