煤灰掺杂对气化条件下生物质中不同无机形态钾迁移转化的影响  

Effects of the addition of coal ash on the transformation of different types of inorganic K in biomass during gasification

作　　者：何紫萌 邓玉洁 石文举 曹景沛[1] 赵小燕 HE Zimeng;DENG Yujie;SHI Wenju;CAO Jingpei;ZHAO Xiaoyan(Jiangsu Province Engineering Research Center of Fine Utilization of Carbon Resources,China University of Mining&Technology,Xuzhou221116,China)

机构地区：[1]中国矿业大学江苏省碳资源精细化利用工程研究中心,江苏徐州221116

出　　处：《煤炭学报》2023年第6期2326-2339,共14页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(22108292)。

摘　　要：钾(K)是生物质中一种主要无机元素,在生物质气化过程中它的迁移转化会造成结渣、积灰和灰团聚等问题,掺杂富含硅(Si)和铝(Al)的煤灰是解决这些问题的有效途径之一。大部分生物质中K主要以K_(2)CO_(3)、K_(2)SO_(4)和KCl等水溶性无机盐形式存在,但不同种类生物质中这几种无机K盐组成差异较大,导致气化过程中灰团聚、结渣行为有较大差异。因此,该研究利用了负载K_(2)CO_(3)、K_(2)SO_(4)和KCl的松木模拟含不同无机形态K的生物质,在水蒸气和CO_(2)气氛下,系统研究了气化过程中煤灰对不同无机形态K迁移转化和在流化床条件下(石英砂为床料)灰团聚行为的影响。研究发现,尽管2种煤灰的晶体矿物组成不同,在气化过程中它们均与负载K_(2)CO_(3)和K_(2)SO_(4)的松木反应形成了钾霞石(KAlSiO_(4))。然而,对于负载KCl的松木,相比于水蒸气气氛,由于煤灰在CO_(2)气氛下生成钾霞石的能力较弱,因此大部分KCl主要通过物理吸附保留,导致K保留比较低。另外,负载KCl的松木气化残渣中K的保留比显著低于负载K_(2)CO_(3)或K_(2)SO_(4)的松木,说明生物质中KCl易挥发且与煤灰的反应较弱,更易造成灰沉积和腐蚀等问题。然而,热力学平衡计算表明3种K盐和煤灰反应主要生成白榴石或长石,与实验结果差别较大。最后,尽管煤灰的加入不能阻止团聚物形成,但抑制了负载K盐的松木和石英砂生成低温熔融硅酸钾的过程,使形成的团聚物更易破碎,可以有效缓解流化床中的灰团聚等问题。Potassium(K)is a major inorganic element in biomass.The transformation of K during biomass gasification can cause slagging,ash deposition and agglomeration problems.The addition of coal ash rich in Si and Al is one of the effective methods to solve these problems.In most biomass,K mainly exists in the form of water-soluble inorganic salts,such as K_(2)CO_(3),K_(2)SO_(4) and KCl.However,the content of these K salts varies significantly with the species of biomass,which leads to the significant differences in the agglomeration and slagging behaviors during gasification. Therefore, the research utilized pine wood doped with K_(2)CO_(3), K_(2)SO_(4) and KCl to simulate different types of inorganic K in biomass. The effect of coal ash on the agglomeration in the fluidized-bed reactors (silica sand as the bed material) and the transforma-tion of different types of inorganic K in biomass was studied systematically during steam and CO_(2) gasification. Although two kinds of coal ash with different mineral compositions were used, the K_(2)CO_(3)-doped and K_(2)SO_(4)-doped pine wood react with both kinds of ash to form kaliophilite (KAlSiO_(4)) during gasification. However, under the CO_(2) atmosphere, for the KCl-doped pine wood, most of KCl is mainly retained by physical adsorption because the ability to form KAlSiO_(4) is weaker than that under the steam atmosphere, which results in a lower K retention ratio under the CO_(2) atmosphere. In ad-dition, the K retention ratio of KCl-doped pine wood is significantly lower than that of pine wood loaded with K_(2)CO_(3) and K_(2)SO_(4), which suggests that KCl in biomass tends to release and reacts with coal ash only to a limited extent. Therefore, KCl in biomass is more likely to cause ash deposition or corrosion problems. However, the results of thermodynamic equi-librium calculations indicate that the reaction between the three types of K salts and coal ash mainly forms leucite or feld-spar, which are significantly different from the experimental results. Lastly, although

关 键 词：生物质 煤灰 无机形态钾 气化 迁移转化 灰团聚 

分 类 号：TK62[动力工程及工程热物理—生物能]