煤中钠元素赋存形态对亚微米颗粒物形成的影响研究

将原煤通过三步化学提取实验(水洗,NH_3OAc洗,HCl洗),然后通过浸溶实验(Impregnation Experiment),将煤中羧基(-COOH)中的H离子置换成Na离子.并将原煤、提取实验后煤和浸溶实验后的三种煤样在沉降炉中热解和燃烧,研究煤中钠的有机/无机赋存形态对其气化特征和亚微米颗粒物形成的影响.实验结果发现:提取实验后的煤样,Na元素大部分以硅酸盐形式存在,两种煤在沉降炉中的热解结果表明以硅酸盐形式存在于煤中的钠元素很难气化.浸溶实验后的煤样中,Na元素大部分以羧酸(COO-Na)的形式存在,两种煤在沉降炉中的热解实验结果表明以有机结合态存在于煤中的钠元素非常易气化.Na元素赋存形态对其燃烧过程中气化有重要影响,最终表现在亚微米颗粒物中的含量上.

STUDY OF OCCURRENCE MODE OF SODIUM EFFECT ON THE SUBMICRON ASH PARTICLE FORMATION DURING COAL COMBUSTION

Chemical fractionation WaS used to selectively extract elements,from the raw coal based on solubility(water,ammonium acetate and hydrochloric acid),and reflects their association in the coal.The residue was an H-form coal sample.Then an impregnation experiment of H-form coal used to change Na~+ cations through ion-exchange process in coal matrix was carried out.The residue was a Na-form coal sample.Finally,the raw coal,H-form coal and Na-form coal samples were pyrolyzed and combusted in the drop tube furnace.The experimental results indicate that,in the H-form coal,the presence of element Na was mostly associated with inorganic silicate mineral species and this form of Na was difficult to be vapored during coal pyrolysis and combustion.In the Na-form coal,the Dresence of element Na was mostly associated with organic carbon matrix and this form of Na was easy to be vapored during coal pyrolysis and combustion.The submicron ash particles were formed with the vaporization and condensation.Hence,the occurrence mode of Na in coal was greatly influenced submicron ash particle formation.