【摘要】 选用马弗炉和平面火焰携带流反应器(FF-EFR)开展了神华煤在不同气氛下的灰化实验,利用X射线衍射仪(XRD)、热分析仪(TG/DSC)、扫描电镜(SEM)以及能谱仪(EDS)对收集到的灰样进行表征,探究了神华煤灰熔融性温度低的原因,考察了灰熔点温度和灰分中矿物质成分含量受气氛的影响.结果表明,神华煤灰熔点普遍偏低,主要原因在于煤中存在大量的Ca和Fe,参与反应产生各种低熔点化合物;传统方式测得灰熔点可以代表实际锅炉中燃煤灰熔点,但不能直接表征高氧浓度燃烧反应时灰分实际熔融性特征;不同气氛下主要燃烧产物种类不变,区别在于富氧燃烧时会产生在空气中燃烧时没有的Ca CO3,从而降低富氧条件下灰熔点并加重结渣情况;富氧条件下Fe矿物形态相对空气气氛下玻璃体更多,赤铁矿更少,这些原因导致神华煤在富氧条件下结渣更严重.更多还原

【Abstract】 Ash sample collection of Shenhua coal with high Ca and Fe content was carried out in Muffle furnace and FF-EFR in different conditions. XRD,TG/DSC,SEM-EDS were used to characterize the ash melting behavior and mineral conversion,which have a great influence in slagging potential. The results showed that traditional ash fusion point test result can basically represent the actual coal-fired boiler ash melting point. But under high oxygen concentration,the ash melting point is somehow higher than what is known from AFT,due to their different reaction mechanisms. The presence of a large number of Ca,Fe in Shenhua coal,which are involved in the reaction to produce a variety of low-melting compounds,is the main reason for its low ash melting point. The influence of different temperatures on the fly ash crystal mineral species is mainly in the Ca. In oxygen enriched combustion,Ca CO3 will be producted,which is not found in air atmosphere,thus increasing the slagging potential. Due to the reducing atmosphere and low temperature of oxygen enriched combustion,more iron melt into glass silicates and few iron oxides are formed,hence resulting in the worsening slagging condition..更多还原