Multistage Reaction Characteristics and Ash Mineral Evolution in Coal–Biomass Co-Combustion Process

Yun Hu, Bo Peng, Songshan Cao, Zenghui Hou, Sheng Wang and Zefeng Ge ()
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Yun Hu: State Key Laboratory of Low-Carbon Smart Coal-Fired Power Generation and Ultra-Clean Emission, China Energy Science and Technology Research Institute Co., Ltd., Nanjing 210023, China
Bo Peng: School of Energy and Environment, Southeast University, Nanjing 210096, China
Songshan Cao: State Key Laboratory of Low-Carbon Smart Coal-Fired Power Generation and Ultra-Clean Emission, China Energy Science and Technology Research Institute Co., Ltd., Nanjing 210023, China
Zenghui Hou: School of Energy and Environment, Southeast University, Nanjing 210096, China
Sheng Wang: State Key Laboratory of Low-Carbon Smart Coal-Fired Power Generation and Ultra-Clean Emission, China Energy Science and Technology Research Institute Co., Ltd., Nanjing 210023, China
Zefeng Ge: School of Energy and Environment, Southeast University, Nanjing 210096, China

Energies, 2025, vol. 18, issue 18, 1-19

Abstract: This study investigates the combustion characteristics and ash behavior of coal–biomass co-combustion using Zhujixi coal and corn straw in a fixed-bed system. The research analyzes combustion stage division, gas release patterns, and mineral evolution of ash under varying blending ratios. Results indicate that biomass addition modifies the dynamic features of the combustion process by advancing the CO 2 release peak; extending the release of CO, CH 4 , and H 2 ; and enhancing the completeness of char oxidation. At moderate blending levels (20–60%), oxygen utilization is significantly improved and combustion stability is strengthened. Ash fusion temperatures exhibit a consistent decline with increasing biomass proportion due to the formation of low-melting eutectic phases such as KAlSiO 4 and K, Ca-based phosphates. Mineralogical analysis further reveals that coal ash components promote the immobilization of alkali metals, thereby suppressing potassium volatilization. A blending ratio of 40% demonstrates the most favorable balance between burnout performance, oxygen efficiency, and alkali fixation, surpassing both pure coal and high-ratio biomass conditions. This optimized ratio not only improves energy conversion efficiency but also reduces slagging and corrosion risks, offering practical guidance for cleaner coal power transformation, stable boiler operation, and long-term reduction of carbon and pollutant emissions.

Keywords: coal-biomass co-firing; combustion characteristics; segmented analysis; ash performance; alkali metal solidification (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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