Preheating and combustion characteristics of pine biomass particles
Pine biomass particles as a fuel source and integrated advanced self-preheating combustion technology was employed to achieve fluidized combustion within the furnace.The preheating modifications of woody biomass particles under different preheating temperatures were examined using a kilowatt level preheating combustion test rig.BET,SEM scanning electron microscopy and Raman spectral band comparison methods were employed to detect and analyze the specific surface area,total pore volume,nitrogen isothermal adsorption and desorption characteristics,particle morphology and other key physical property parameters of high temperature biomass semi-coke.The findings indicate that an increase in preheating temperature results in a noticeable rise in nitrogen adsorption amount,suggesting that the modified biomass semi-coke possesses a more developed pore structure.The depolymerization and devolatilization of pine biomass par-ticles at high heating rates,combined with the analysis of carbon microcrystalline structure,result in the disruption of macromolecular car-bon chains and the generation of small molecular volatiles,thereby enhancing reactivity.The modified high-temperature biomass semi-coke exhibits rapid attainment of stable combustion within the descending combustion chamber,with a remarkable combustion effi-ciency reaching 99%in terms of its combustion characteristics.In terms of NOx emissions,the combustion temperature is maintained at 1 100℃under all experimental conditions to prevent the formation of thermal NOx.It is noteworthy that the concentration of NOx emis-sions from pine biomass particles does not exhibit a linear relationship with preheating temperature.Specifically,at 842℃,the concentra-tion of NOx emissions peaks and then begins to decrease.Within the range of test temperatures,when the preheating temperature is set at 705℃,the concentration of NOx emissions reaches its lowest value,namely 97.79 mg/m3.In conclusion,for ensuring low NOx emissions and high combustion efficiency in pine biomass after preheating combustion,this study recommends an optimal preheating temperature of 705℃.
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