含钙和含铁矿物对粉煤气化堵渣的影响机理

Effect mechanism of calcium-bearing and iron-bearing minerals on slag blockage of pulverized coal gasification

为了研究粉煤气化的堵渣机理,选取气流床粉煤气化过程中产生的工业渣样(正常渣样和非正常渣样)和在不同还原性气氛与温度下烧制的试验渣样,利用X-射线荧光光谱(XRF)、X-射线衍射仪(XRD)、扫描电子显微镜和能谱仪(SEM-EDX)等研究渣样的灰成分、晶体矿物组成、微观形貌和微区化学组成等性质,结果表明:非正常渣中钙长石的生成和铁的析出是导致堵渣的主要原因;熔渣析铁的主要原因是在还原性气氛下,赤铁矿被还原的中间产物FeO、FeSx转变的中间产物FeS形成Fe-O-S共熔体;气化炉操作温度的波动易导致钙长石晶体生成,而钙长石的大量析出与铁质矿物的富集和单质铁的析出存在内在联系。

In order to study the mechanism of slag blockage of pulverized coal gasification,the industrial slag samples( normal slag samples and unnormal slag samples) taken from coal gasification unit and the XZ coal ash slag samples( experimental slag samples) obtained from bench scale tube furnace in different temperature and reducing atmosphere were investigated.The ash chemical composition,crystal mineral composition,microscopic morphology and chemical composition of the micro-zone of slag samples were studied by X-ray Fluorescence( XRF),X-ray diffractometer( XRD) and Scanning Electronic Microscopy combined with energy Dispersive X-ray Spectrometer( SEMEDX) respectively.The results show that the main reasons of slag blockage of coal gasification is the formation of anorthite and iron precipation in slag samples.The iron precipation in slag under reducing atmosphere is caused by the formation Fe-O-S eutectic,which is converted by Fe O,Fe Sxand Fe S.The temperature fluctuations of gasifier operation is likely to lead to the formation of anorthite,and the massive formation of anorthite in slag is intrinsically linked to the enrichment of iron minerals and the precipitation of elemental iron.