循环灰吸附碱金属机理研究

加入添加剂脱除蒸汽中的碱金属盐是防止准东煤等高钠煤在应用过程中由于高碱金属含量造成沾污、结渣及高温腐蚀等风险的重要手段。在实验室条件下用山东临沂135 MW循环流化床循环灰作为添加剂与钠盐(NaCl)进行掺烧,分别采用热重分析仪(TGA)和马弗炉进行,对不同温度(800,850,900℃)、不同掺混比例(1%,2%,3%,5%,8%)下循环灰掺烧碱金属盐后的样品进行XRF,XRD等测试。XRF测试结果表明,在800~900℃下,掺烧实验得到的循环灰样品中Na含量远高于Cl含量,且随着温度的升高,相同掺混比例下循环灰中Cl含量随着温度的升高而下降。在相同温度下,Na元素含量随掺混比例的增高而增加,Cl含量增长远低于Na含量增长。XRD测试结果表明:掺烧后灰样中Na主要以硅铝酸盐等不可溶钠形式存在,循环灰对NaCl的吸附以化学吸附为主。

Mechanism study of adsorption of alkali with bed material

Alkali in high sodium coal causes a variety of problems including fouling，the corrosion of heating surface.It is feasible to capture alkali vapors with bed material，which is used as adsorbent.The fundamentals of the adsorption of alkali with bed material were studied through experiments.The mixture of NaCl and bed material was heated in thermogravimetric analysis (TGA) and muffle furnace.X ray diffraction (XRD) and X ray Fluorescence (XRF) were conducted for the burned materials.The XRF test results show that the Na content is much higher than the Cl content in the burned sample at 800-900 ℃ and at the same blending ratio，the Cl content decreases as the temperature rises.At the same temperature，there is almost no Cl element in the burned sample while the Na content increases with the increase of the blending ratio.The XRD test results show that Na mainly exists in the form of unsolvable sodium in the burned materials such as sodium silicoaluminate.The test results demonstrate that the adsorption process is mainly chemical adsorption.