碱金属钾对秸秆燃烧成灰特性的影响

THE INFLUENCE OF POTASSIUM ON ASH CHARACTERISTIC DURING STRAW COMBUSTION

以麦秆灰和稻秆灰为研究对象,利用灰熔融实验和XRD、SEM等分析测试手段结合K的形态分布预测,考查碱金属K对秸秆成灰特性的影响。结果表明:麦秆灰和稻秆灰中K的主要存在形式分别为K2SO4和K2O·2SiO2。K含量增多对麦秆灰和稻秆灰中K2SO4、KAlSiO4、KAlSiO4(K)、KAlSi3O8含量的影响较小。K2CO3、K2O·2SiO2、K2O·SiO2的物质的量分数随K含量的增加而增多是诱发灰熔融特征温度下降的重要原因之一,此外它们与其他矿物质形成复杂的低熔点共熔物也对其起到重要作用。

The form of potassium in ashes plays an important role in energy utilization and fusing characteristics of straw ashes. The effects of potassium on the ash characteristics of wheat and rice straw were studied by ash melting point apparatus, X-ray powder diffraction （XRD） and scanning electron microscope （SEM）. In addition thermo- dynamic equilibrium calculations were used to predict the morphology and distribution of potassium in solid phase and interpret the experimental results. It was found that K2SO4 and K2O·2SiO2 are the main form of wheat and rice straw ashes, respectively. It has little effect on the amount of K2SO4, KAlSiO4, KAlSiO4（K） and KA1Si3Osin wheat and rice straw ashes as increasing potassium content in fuels. Increasing molar fraction of K2O·2SiO2, K/CO3 and K2O·2SiO2 with potassium content increasing was one of important reasons that caused the reduction of ash fusion temperature. Meanwhile, it was related to the complex low melting point eutectic mixtures formed by K2O·2SiO2, K2CO3,K2O·2SiO2 with other minerals.