生物质与烟煤灰的理化特性及混合灰熔融特性研究

文章利用扫描电子显微镜(SEM)、X射线荧光光谱仪(XRF)、X射线荧光衍射仪(XRD)、灰熔融特性分析仪对4种生物质(海草、梨木、榛子壳、稻秆)灰与神木烟煤灰的混合灰的熔融特性进行了研究。研究发现:水生生物质(海草)灰的掺混使混合灰的熔融特性温度先升高再降低;两种木本生物质(梨木和榛子壳)灰的掺混使混合灰的熔融特性温度逐渐升高;草本生物质(稻秆)灰的掺混对混合灰熔融特性温度的影响与水生生物质灰类似。由XRF分析可知:Na2O和CaO对于混合灰的熔融特性温度有更明显的影响,随着混合灰中Na2O含量的逐渐增加,混合灰的熔融特性温度逐渐下降;随着混合灰中CaO含量的逐渐增加,混合灰的熔融特性温度逐渐上升。由XRD结果可知:水生生物质灰在高温下容易形成熔点较低的碱金属硅酸盐,使混合灰的熔点降低;木本生物质灰中的CaCO3含量较高,能够提高混合灰的熔点;草本生物质灰与水生生物质灰类似,含有的低熔点碱金属硅铝酸盐使混合灰的熔点降低。

Study on physicochemical characteristics of biomass and bituminous coal ash and melting characteristics of mixed ash

Co-firing biomass and coal is one of the effective ways to use biomass and has received extensive attention.However,problems such as ash deposition and slagging caused by the addition of biomass have not been solved.In this paper,the ash fusion characteristics of four biomass ash(seaweed,pear wood,hazelnut shell,rice straw)and Shenmu bituminous ash were studied by scanning electron microscope(SEM),X-ray fluorescence spectrometer(XRF),X-ray fluorescence diffractometer(XRD)and ash fusion spectrometer.The study found that as the mixing ratio of the four biomasses ash increases,the temperature variation trend of the mixed ash fusion characteristics is also different.Mixing of aquatic biomass(seaweed)ash increases the melting temperature of mixed ash and then decreases it;mixing of two kinds of woody biomass(pear wood and hazelnut shell)ash increases the melting temperature of mixed ash gradually;mixing of herbaceous biomass(rice straw)ash has a similar effect on the melting characteristics of mixed ash as aquatic biomass ash.Combined with the XRF analysis results,it indicates that that the fusion characteristics of ash is significantly affected by the contents of Na2O and CaO.With the increase of Na2O content in mixed ash,the temperature of mixed ash fusion characteristics decreases.While,the increasing of CaO content in mixed ash leads to an increasing of the fusion characteristic temperature of mixed ash.XRD analysis further shows that aquatic biomass ash easily forms lower-melting alkali metal silicates at high temperatures,reducing the melting point of mixed ash.Woody biomass contains more CaCO3,which can improve the melting point of mixed ash.Similar to aquatic biomass ash,herbaceous biomass ash contains low melting point alkali metal silicoaluminate which reduces the melting point of mixed ash.