高碱煤中碱金属含量测定及应用进展

Determination of alkali metal content in high alkali coal and its application

GB/T 1574—2007高温灰化法测定高碱煤中碱金属含量过程中由于部分碱金属释放,无法获得准确的测定值。分析了测定碱金属含量的影响因素以及基于高碱煤中碱金属特殊赋存形式的测定方法与应用现状。测定碱金属含量的影响因素主要包括碱金属赋存形式、预处理温度、升温速率、气氛等。基于高碱煤中碱金属特殊赋存形式的测定方法主要有低温灰化法、直接溶样法、逐级萃取法和氧弹法等,但其重复性和再现性还需进一步验证。未来应重点研究煤中碱金属测定方法的重复性和再现性,建立科学、可靠、便捷的标准方法,开发便捷、高效、低成本的碱金属在线监测技术,以及实现气相碱金属含量与沾污、结渣等工程问题相关性的快速预测。如基于燃烧或气化过程碱金属气相浓度的在线/原位监测技术实用性强,是高碱煤中碱金属定量的发展方向。

According to the national standard method,the high temperature ashing method is widely used to determine the content of alkali metals in coal,but it is difficult to obtain accurate measured values due to release of partial active alkali metals during the ash process.The influencing factors of the determination of alkali metals were analyzed in term of the occurrence form of alkali metals,pretreatment temperature,heating rate,atmosphere,etc.Furthermore,the development and application status of the determination methods based on the special occurrence modes of alkali metals in high alkali coal in recent years,such as low temperature ashing method,direct dissolution method,extraction method and oxygen bomb method,etc.were also discussed. In the future,research should be focud on the repeatability and reproducibility of alkali metal determination methods in coal,establishing scientific,reliable and convenient standard methods,developing convenient,efficient and low-cost on-line alkali metal monitoring technology and realizing rapid prediction of correlation between alkali metal content in gas phase and engineering problems such as contamination and slagging.It proposes that the in-situ monitoring technology based on the concentration of alkali metals in combustion or gasification process is highly practical and may be the research direction of the quantitative determination of alkali metals in high alkali coal.