高碱煤热烟气强化水洗脱碱机制及动力学分析

Mechanism and Kinetic Analysis of Flue Gas Enhanced Water Leaching Dealkalization on High Alkali Coal

基于低p H浸洗促进高碱煤中碱金属和碱土金属(AAEM)的增溶原理,将电厂烟气(CO_(2))作为酸源并将余热资源化利用,团队前期开发出一种针对高碱煤的热烟气强化水洗脱碱技术(FG-WL)。本文对不同形态AAEM的脱除及关键参数的影响规律和机制进行了较详细讨论,通过动力学计算确定AAEM不同时间段的控制步骤和参数。结果表明,FG-WL的温度从25℃升至60℃,高碱煤120 min的脱钠率从80.7%升至94.7%,40 min的脱钙率从32.5%提升至38.7%;处理0~40 min的碱金属(Na、K)脱除主体为水溶态,且为固膜扩散控制,40 min后以醋酸铵溶态为主,且为化学反应控制;碱土金属(Ca、Mg)的全程以醋酸铵溶态脱除为主并伴随部分盐酸溶态,且为固体膜控制。本研究可为此方法的工艺优化和参数调节提供一定指导。

Based on the principle of low pH leaching to promote the solubilization of alkali and alkaline earth metals(AAEM)in high alkali coals,using power plant flue gas(CO_(2))as an acid source and resource utilization of waste heat,the authors’team has developed a hot flue gas enhanced water leaching dealkalization technology(FG-WL)for high alkali coals in advance.In this paper,the removal of different forms of AAEM and the influence laws and mechanisms of key parameters are discussed in more detail,and the control steps and parameters of AAEM in different durations are determined by kinetic calculations.The results showed that the temperature of FG-WL was increased from 25℃ to 60℃,and the removal rate of Na increased from 80.7%to 94.7%for 120 min,and the removal rate of Ca increased from 32.5%to 38.7%for 40 min;The main subject of alkali metal(Na,K)removal from treatment 0∼40 min was water soluble state and controlled by solid film diffusion,and after 40 min the ammonium acetate soluble state was dominant and controlled by chemical reaction;The removal of alkaline earth metals(Ca,Mg)throughout the process is dominated by the ammonium acetate solvation state accompanied by some hydrochloric acid solvation state,and is controlled by a solid film.This study can provide some guidance for process optimization and parameter adjustment of this method.