摘要
准东煤田是我国已探明的最大煤田,但由于准东煤普遍含有较高的Na,Ca,Mg,Fe等碱性元素,其燃烧利用过程中出现了严重的沾污结渣问题。为解决准东煤的沾污结渣问题,有必要对其无机元素在燃烧过程中的转化机理进行深入研究。采用逐级提取的方法对准东煤进行处理,依次制备了水洗煤、乙酸铵洗煤和盐酸洗煤,在沉降炉中开展了各煤样的颗粒物生成特性实验,研究了准东煤中不同形态无机元素向颗粒物的转化行为。燃烧温度1 300℃,模拟空气燃烧气氛,气流量10 L/min,给粉速率0. 1 g/min。使用低压撞击器(LPI)收集燃烧生成的颗粒物,使用精密电子天平称量颗粒物的质量,获得其质量粒径分布规律;采用扫描电子显微镜和能谱(SEM-EDS)分析颗粒物的成分和形貌。研究表明,准东煤中Na主要以水溶态形式存在,Ca和Mg主要以乙酸铵溶态和盐酸溶态形式存在,Fe主要以盐酸不溶态和盐酸溶态形式存在。燃烧后生成的颗粒物主要分布在1~10μm,并且主要来自煤中乙酸铵溶态和盐酸溶态Ca,Mg的转化。它们大部分形成富Ca,Mg的烧结状无规则形貌颗粒,小部分形成球形的硅铝酸盐颗粒。Na很大一部分生成PM1(尤其是PM0. 1),其他则以硅铝酸盐形式分布在PM1~10中。Fe燃烧后主要分布在PM1~10中,其中盐酸溶态Fe有较大贡献。通过本研究可以认识到有机结合态和盐酸溶态元素是引起准东煤沾污结渣的主要元素形态,通过酸洗去除准东煤中的部分无机元素是缓解其沾污结渣的一种可行方法。
Zhundong coal field is the largest coal field in China.However,the content of Na,Ca,Mg and Fe in the coal is usually very high,which has caused severe slagging and fouling problems during Zhundong coal combustion.In order to solve the slagging and fouling problems,the transformation mechanism of inorganic elements during combustion should be well understood.This study aims to investigate the transformation of inorganic elements in different forms into ash particles during Zhundong coal combustion.A set of coal samples were prepared by water washing,ammonium acetate washing and diluted hydrochloric acid washing.All the coals were burned in a drop tube furnace at 1 300 ℃ in air condition.The air flow rate was 10 L/min.Coal was fed at the rate of 0.1 g/min.The combustion generated ash particles were collected by a low pressure impactor( LPI).The mass of particles was measured by a precision balance.The composition and morphology were analyzed by SEM-EDS.The results showed that Na was mainly in water soluble form.Ca and Mg were mainly in the ammonium acetate soluble and hydrochloric acid soluble form.While Fe was mainly in the hydrochloric acid soluble and insoluble form.After combustion,most of the ash particles were distributed in the range of 1-10 μm.These particles mainly came from the ammonium acetate soluble and hydrochloric acid soluble Ca and Mg in the coal.Most of them were irregular in shape with high content of Ca and Mg.The remaining particles were Ca/Mg contained alumino-silicates with spherical shapes.Na mainly contributed to the formation of PM1( especially to PM0.1),and the rest was presented in PM1-10.Fe was mainly distributed in PM1-10,and the contribution of acid soluble Fe was significant.From this study,it can be found that inorganic elements in the form of ammonium acetate soluble and hydrochloric acid soluble were the key that resulted in the ash deposition of Zhundong coal.The use of acid to remove the inorganics in the coal is a way to mitigate the ash deposition problem.
作者
曾宪鹏
于敦喜
于戈
刘芳琪
刘虎平
徐明厚
ZENG Xianpeng;YU Dunxi;YU Ge;LIU Fangqi;LIU Huping;XU Minghou(State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2019年第2期588-595,共8页
Journal of China Coal Society
基金
国家重点研发计划资助项目(2016YFB0600601)
国家自然科学基金面上资助项目(51676075)
国家自然科学基金重点国际合作资助项目(51520105008)
关键词
准东煤
无机元素
赋存形态
灰形成
颗粒物
Zhundong coal
inorganic elements
mode of occurrence
ash formation
particulate matter