STUDY ON CHEMICAL STRUCTURE EVOLUTION AND REACTIVE MECHANISM OF BIOMASS CHAR PREPARED IN CO2/H2O ATMOSPHERE
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摘要: 以水稻秸秆(RS)为研究对象,研究了CO2/H2O气氛对其脱挥发分过程中焦产率、结构及其反应性的影响。采用傅里叶红外光谱(FTIR)及拉曼光谱(Raman)对不同条件下制备的RS焦进行表征,阐明不同反应气氛下RS焦的微观化学结构演化规律。采用热重分析仪(TGA)对制备的RS焦的燃烧反应性进行分析,揭示了CO2气氛、H2O气氛与CO2/H2O混合气氛对RS焦微观化学结构演化及反应性的作用机理。结果表明:CO2/H2O气氛下,生物质焦产率随着反应终温升高而降低,且在700 ℃以上焦产率差异较大;CO2/H2O混合气氛更有利于促进生物质焦中小芳香环系统的消耗和缩聚,CO2和H2O气氛在高温下对生物质焦的反应存在协同作用和竞争关系;制焦温度在700 ℃以上时,CO2/H2O气氛有助于改善生物质焦的燃烧特性。Abstract: With rice straw(RS) as the research object, the effects of CO2/H2O atmosphere on biomass yield, structure and reactivity of RS in the process of volatilization were investigated. Fourier transform infrared spectroscopy (FTIR)and Raman spectroscopy (Raman) were used to characterize the RS char, and the evolution law of the microchemical structure of RS char under different reaction atmospheres was investigated. The combustion reactivity of RS char was analyzed by a thermogravimetric analyzer (TGA), and the effects of CO2 atmosphere, H2O atmosphere and CO2/H2O mixture atmosphere on the microstructure evolution and reaction mechanism of RS char were revealed. The results showed that the yield of biomass char decreased with the increase of final reaction temperature in CO2/H2O atmosphere, and the difference of yield of biomass char was obvious when the reaction temperature was above 700 ℃. CO2/H2O mixture atmosphere was more conducive to the consumption and condensation of the small aromatic ring system of biomass char. CO2 atmosphere and H2O atmosphere had a synergistic effect and competitive relation in the reaction of biomass char at high temperature. CO2/H2O atmosphere could improve the combustion characteristics of biomass char when the char-making temperature was 700 ℃ above.
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Key words:
- rice straw /
- oxy-fuel combustion /
- biomass char /
- chemical structure /
- reactivity
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