再燃温度对稻壳焦理化结构演变的影响

利用高温携带流装置,在再燃条件下获得了不同的稻壳焦。采用元素分析、SEM-EDS分析、N2吸附-脱附、ICP-AES、XRD和FT-IR等手段对稻壳焦的理化结构进行了分析与表征,研究了再燃温度对稻壳再燃过程中灰焦理化结构演化规律的影响。结果表明,在850-1 150℃,反应温度的升高有利于稻壳焦孔隙结构的形成,进而有效提高稻壳焦的比表面积和孔容积。稻壳中碱(土)金属元素的释放顺序为NaCaMgK,且随温度升高,碱(土)金属元素的释放率呈现先略微升高后逐渐趋于稳定的趋势,氯的释放率逐渐增大。稻壳焦中的碱(土)金属主要以硅酸盐和硫酸盐的形式存在。稻壳焦表面含氧官能团随反应温度的升高逐渐减少。

Effect of reburning temperature on physico-chemical characteristics evolution of rice husk char

Different kinds of rice husk (RH) char were prepared in an entrained flow reactor under reburning conditions. The physico-chemical properties of pyrolyzed RH chars were characterized by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), specific surface area and pore size analyzer, X-ray diffraction (XRD) and Fourier transform infra-red (FT-IR) spectroscopy, respectively. The effects of temperature on evolution of physico-chemical structures of RH chars were discussed. The results indicate that the specific surface area and pore volume of RH chars increase significantly from 850 to 1 150 ℃. The order of release of alkaline and alkaline earth metals (AAEMs) bound in RH is Na > Ca > Mg > K. With increasing reaction temperature, release fractions of AAEMs generally increase firstly and then being stable, and the chlorine release fraction increases gradually. AAEMs in RH chars are mainly in the form of silicate and sulfate. The surface oxygen-containing functional groups in RH chars decrease significantly with increasing temperature.