高钠煤气化过程中的灰化学研究进展  

Research process on ash chemistry of high-sodium coal during gasification

作　　者：张显显 白进[1] 孔令学[1] 李怀柱[1] 郭振兴[1] 白宗庆[1] 李文[1] ZHANG Xianxian;BAI Jin;KONG Lingxue;LI Huaizhu;GUO Zhenxing;BAI Zongqing;LI Wen(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry of Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,山西太原030001 [2]中国科学院大学,北京100049

出　　处：《洁净煤技术》2023年第7期110-124,共15页Clean Coal Technology

基　　金：国家自然科学基金资助项目(22178370,22078352);山西省重点研发计划资助项目(202102090301004)。

摘　　要：煤气化是发展煤基大宗化学品及清洁燃料的关键技术,也是实现双碳目标的重要途径。准东高钠煤中碱金属钠含量高,气化过程中碱金属钠释放造成严重的灰释放问题,因此,探究准东高钠煤在气化过程中灰沉积、结渣机理及煤灰流动性对准东煤的清洁高效利用具有重要意义。鉴于此,综述了近年来气化过程中高钠煤的灰化学研究最新进展。总结了煤中钠的赋存形态及含量,阐明了气化过程中钠的迁移转化机制及钠释放导致气化炉受热面造成的灰沉积、结渣问题。由于高钠煤中钠释放主要受气化温度的影响,因此成灰温度不宜高于500℃。气化过程中易生成熔点低的含钠矿物质,降低高钠煤煤灰熔融温度。高钠煤中钙、铁含量高时,煤灰中钙长石及钙铝黄长石在高温下生成低温共晶体、Fe^(2+)与煤中矿物质反应形成低熔点尖晶石均是加剧煤灰熔融的重要原因。同时,热转化过程中气氛对高钠煤中矿物演化具有一定影响。高钠煤灰的熔融区间窄,熔融速率快,表明高钠煤灰流动性强,由于Na+的离子势较低,O_(2)^(-)被Si^(4+)夺取,导致桥氧键断裂成非桥氧键,熔渣网格结构解聚,黏度降低,其熔融机理符合“熔融-溶解”机理。降温过程中晶体的析出对黏度的影响至关重要。Na_(2)O的引入降低了熔渣析晶体温度,改变晶体类型,同时降低熔渣的黏滞活化能及结晶能力。Coal gasification is a key technology to develop coal based bulk chemicals and clean fuels,and also an important way to achieve the goal of carbon neutrality.High sodium content and its volatilization of Zhundong coal during gasification lead to serious ash-release problems.Therefore,it is of great significance to clarify the ash deposition and slagging mechanism and ash fluidity during Zhundong coal gasification for the clean and efficient utilization of high-sodium coal.Given this,the research progress on the ash chemistry of high-sodium coal during gasification process was reviewed.The forms and content of sodium in coal were summarized.The migration and transformation mechanisms of sodium in gasification and the ash deposition problem caused by sodium release on the heating surface of the gasifier were clarified.The ashing temperature is set at 500℃ because the sodium release in high sodium coal is mainly affected by the gasification temperature.Low melting point sodium-containing minerals are easily generated during the gasification process,reducing the ash melting temperature of high sodium coal ash.When the content of calcium and iron in high sodium coal is high,the formation of low-temperature eutectic of anorthite and gehlenite in coal ash at high temperature,and the formation of low melting point spinel by Fe 2+reacting with minerals in coal are important reasons for reducing coal ash melting temperature.Meanwhile,the atmosphere has a certain influence on the minerals evolution of high-sodium coal during thermal conversion.The melting rate of high-sodium coal is fast,and the average melting temperature is low,indicating that the ash has a strong fluidity.The Na_(2)O can provide O_(2)^(-)and break the bridge oxygen bonds,causing the slag to depolymerize and reducing the viscosity value.The slag grid structure depolymerizes,the viscosity is reduced.The melting mechanism confirms the melting-dissolution mechanism.The precipitation of crystals in the slag during cooling has a crucial impact on the viscosi

关 键 词：气流床气化 高钠煤 灰沉积 熔融特性 黏温特性 

分 类 号：TQ53[化学工程—煤化学工程]