超级芦竹在CFB燃烧过程的积灰特性实验研究

An Experimental Investigation into Ash Deposition Characteristics During Combustion of Super-arundo Donax in CFB

超级芦竹是一种新型能源植物,具有固碳能力强、发热量高的特点。为研究超级芦竹燃用过程的灰沉积问题,在小型(0.2 t/d)循环流化床(circulating fluidized bed,CFB)上进行了超级芦竹的纯燃以及其与煤共燃的实验,利用空冷取样探针,结合扫描电子显微镜耦合能谱仪(SEM‒EDS)、X射线衍射仪(XRD)及FactSage 8.2热力学计算软件,研究了燃烧过程的积灰特性。研究结果显示,超级芦竹在CFB纯燃时,取样探针上形成致密烧结灰层。灰层富含碱金属钾(K)且主要以KCl、K_(2)SO_(4)等低熔点矿物存在。同时,氯元素(Cl)的存在也导致取样探针发生严重腐蚀。当超级芦竹与煤耦合燃烧时,沉积灰中的K、Cl、硫(S)含量及对应的低熔点硫酸盐/硅酸盐含量逐渐降低,受热面积灰倾向明显减弱。同时飞灰中高熔点钾/钙/钠硅铝酸盐含量相应地增加,飞灰灰熔融特征温度得以提升,研究结果为CFB清洁高效利用超级芦竹提供了可行性借鉴。

Super-arundo donax(SAD)is considered a new energy plants due to its efficient carbon sequestration and high calorific value.In order to study the problem of ash deposition during its combustion,super-arundo donax combustion and super-arundo donax-coal co-combustion experiments are conducted on a 0.2 t/d circulat⁃ing fluidized bed(CFB).Moreover,the ash deposition characteristics on the heating surface during super-arun⁃do donax combustion are analyzed by air-cooled sampling probes,environmental scanning electron microscopy coupled with energy dispersive X-ray spectroscopy(SEM-EDS),X-ray diffraction(XRD)and FactSage 8.2 thermodynamic calculation software.The results showed that,a dense sintered layer is formed on the sampling probe during super-arundo donax combustion,which is rich in alkali metal K existing in the form of low melting point minerals such as K2SO4 and KCl. At the same time, the presence of Cl also lead to severe corrosion of thesampling probe. When the combustion of arundo donax and coal is coupled,the K, Cl,S content and correspond⁃ing low melting point sulfate/silicate contents in the deposition ash gradually decrease as the proportion of superarundodonax blending decrease. The tendency of ash deposition is significantly weakened when the proportion ofsuper-arundo donax decrease. While the contents of high melting point K/Ca/Na silicoaluminates increase ac⁃cordingly,resulting an increase in the ash fusion temperature of fly ash. The results provide feasible reference forthe clean and efficient utilization of super-arundo donax by CFB.