Abstract:

Aiming at the problems of high Na content in the coal of the Xinjiang Naomaohu coal mine, which may cause corrosion and contamination of the inner wall of the gasifier, gasifier slagging and contamination and poor slag discharge during the gasification process, the migration behavior of sodium in Naomaohu coal during CO₂ gasification process was studied by laboratory gasification test and Factsage thermodynamic simulation test. The gasification reaction characteristics of Naomaohu coal were studied by thermogravimetric experiment. Using SEM-EDS, XRD, ICP-OES and other methods, the residue of Naomaohu coal at 800—1100℃ under the CO₂ gasification conditions was analyzed and characterized. Combined with the calculation method of chemical thermodynamic equilibrium, the distribution of Na in Naomaohu coal in the gas phase during CO₂ gasification was studied, and the precipitation characteristics of Na during the gasification process were analyzed. The results showed, as the temperature increased within a certain reaction time, the precipitation amount of Na in Naomaohu coal gradually increased at 900—1000℃. The sodium element in the flue gas mainly existed in the form of NaCl(g), NaOH(g) and Na(g). This part of Na was not concentrated in the residue, but was discharged with the flue gas. The main component in the residue at 800℃ was CaCO₃. When the gasification temperature was higher than 900℃, the residue began to melt, and the amount of the eutectic in the residue increased with the increase of temperature. Na in Naomaohu coal existed in the form of aluminosilicate at 800—1100℃.

Key words: Naomaohu, high-sodium coal, gasification, migration behavior, thermodynamic simulation

摘要：

针对新疆淖毛湖煤矿煤中Na含量高，在气化过程中可能会导致气化炉内壁腐蚀、沾污等问题，本文通过开展实验室气化实验和Factsage热力学模拟实验，研究了淖毛湖煤中钠在CO₂气化过程时的迁移行为。通过热重实验研究了淖毛湖煤的气化反应特性；利用扫描电镜-能谱（SEM-EDS）、X射线衍射（XRD）及电感耦合等离子体-原子发射光谱（ICP-OES）等手段，对淖毛湖煤在800～1100℃下CO₂气化条件下得到的残渣进行了分析表征，研究了不同温度下得到的残渣形貌以及残渣中Na的赋存形态、含量变化等；同时，结合化学热力学平衡计算方法，研究了CO₂气化过程中淖毛湖煤中Na在气相中的分布情况，分析了气化过程中Na的析出特性。结果表明，在一定的反应时间内，随着气化温度的逐渐升高， 在温度为900~1100℃下淖毛湖煤中Na的析出量逐渐增加。在煤气中钠元素主要以NaCl（g）、NaOH（g）和Na（g）的形态存在，这部分形态的Na随着煤气排出而未富集于残渣中。800℃时残渣中主要成分为CaCO₃，当气化温度高于900℃时，残渣开始熔融，且随温度的升高残渣中共熔物增加。当温度在800～1100℃时，淖毛湖煤中Na主要以硅铝酸盐的形式存在。

关键词: 淖毛湖, 高钠煤, 煤气化, 迁移行为, 热力学模拟