煤焦气化反应过程中灰的熔融特性变化

Change of ash fusing characteristic in char gasification

抽样选出具有代表性的一种高灰熔点煤种和一种低灰熔点煤种,在TGA-51H型高温热天平上进行煤焦-O2、煤焦-CO2和煤焦-水蒸气气化反应实验,通过扫描电镜(SEM)考察了不同气氛下煤焦气化反应过程中高、低灰熔点煤灰的熔融变化过程,并利用EDX分析了灰的熔融机制。实验结果表明:同种煤样还原性气氛下的灰熔点比氧化性气氛下低;相同条件下灰在CO2气氛下的灰熔点比其在水蒸气气氛下低。在气化反应的过程中,由于气化反应为强吸热过程,大部分热量提供给煤炭气化反应,导致Ca与Fe元素的还原反应进行缓慢,灰熔融温度比较高。

Two typical coals which one is high ash fusion temperature coal and the other is low ash fusion temperature, were selected for being gasified in oxygen, carbon dioxide and steam separately with using TGA -51H. The process of melting char was studied under various gasification conditions with SEM and mechanism of that was ana- lyzed with EDX. The results showed that ash melting point in deoxidized atmosphere was lower than that in oxidation atmosphere; Comparison on ash fusibility temperature was made between gasification in coal-CO2 reducing atmosphere and in coal-H2O reducing atmosphere, of which result showed that ash fusibility temperature in coal-CO2 reducing atmosphere is lower. Due to the intense decalescence that most of heat was supplied to gasification, it is the reason of high ash fusibility temperature that there is hardly any Ca and Fe can be deoxidized in gasification.