煤灰对玉米秸秆焦气化过程中固钾及其灰熔融性的研究

Influence of coal ash on potassium retention and ash fusibility during gasification of corn stalk coke

在管式炉中,研究了煤灰对玉米秸秆焦在不同气化条件下钾的固留率和灰渣熔融性的影响。采用电感耦合等离子体发射光谱(ICP-AES)、X射线衍射(XRD)以及灰熔点测定仪等检测表征手段对气化灰渣中的钾元素含量、矿物质组成以及其熔融点进行了分析。实验以高岭土为参考,研究发现,煤灰如同高岭土具有一定的固钾能力,且随着添加量的增加钾固留率呈现增加的趋势,同时灰渣熔点也得到了提升。灰渣产物的XRD组成分析表明,挥发至气相中的钾以及灰渣中以熔融态存在的钾盐与煤灰中的硅铝化合物反应生成了高熔点的KAlSi_3O_8、KAlSi_2O_6和KAlSiO_4,从而达到固钾的效果并提升了灰渣的熔点。

The potassium fixation ability and ash fusibility in gasification of corn stalk coke blended with coal ash were studied in CO 2 atmosphere using a tube reactor.The ash samples were analyzed by inductively coupled plasma atomic emission spectrometer(ICP-AES),X-ray diffraction(XRD)and ash-melting point measuring device.The results show that coal ash has a certain ability of fixing potassium in the biomass ash as the reference of kaolin and the potassium retention ratio(PRR)increases when adding more coal ash.On the other hand,ash fusion temperatures(AFTs)of the blended ash increase by adding the coal ash,compared with the biomass ash.XRD patterns show that the reaction between alumina/silica compounds in coal ash and potassium that volatilized into the gas phase and existed in slag phase leads to formation of potassium aluminosilicates(KAlSi3O8,KAlSi2O6 and KAlSiO4),which are high melting point compounds.It confirms that coal ash is a potential additive for not only fixing potassium,but also increasing the ash fusion temperatures of easy-to-slagging biomass.