硫酸钠沉积转化特性及对灰熔融性的影响  

Deposition and Conversion Characteristics of NaSO and Its Effect on Ash Fusibility

作　　者：肖海平[1] 时浩 李昕耀 蒋炎飞 刘彦鹏 XIAO Haiping;SHI Hao;LI Xinyao;JIANG Yanfei;LIU Yanpeng(School of Energy,Power and Mechanical Engineering,North China Electric Power University,Changping District,Beijing 102206,China;Datang Thermal Power Technology Research Institute,Shiingshan District,Beijing 100040,China)

机构地区：[1]华北电力大学能源动力与机械工程学院,北京市昌平区102206 [2]中国大唐集团科学技术研究院有限公司火力发电技术研究院,北京市石景山区100040

出　　处：《中国电机工程学报》2021年第1期257-266,共10页Proceedings of the CSEE

摘　　要：Na_(2)SO_(4)是加剧高碱煤沾污结渣特性的重要中间物质。为阐明炉内固相Na_(2)SO_(4)生成转化机理及对灰熔融性的影响规律,采用气相反应动力学分析了Na_(2)SO_(4)(g)的生成,总结了渣层不同温度下Na_(2)SO_(4)的沉积和转化特性,通过灰熔融性和高温矿物演变实验研究了Na_(2)SO_(4)的高温转化及对灰熔融性的影响。结果表明:Na_(2)SO_(4)(g)是气相Na的主要赋存形式。900℃及以下Na_(2)SO_(4)(g)大量凝结并沉积,中低温渣层中的Na_(2)SO_(4)稳定存在。渣层温度沿径向升高,沉积于高烟温区域灰渣外层的Na_(2)SO_(4)熔融,并发生高温转化,与飞灰中石英、刚玉等矿物发生铝硅酸化反应,1 000℃左右大量生成钠长石,硫酸钠含量高时生成钠霞石,高于1100℃进一步转化为钙钠长石、青金石、蓝方石等矿物。Na_(2)SO_(4)高温下转化为低熔点含钠铝硅酸盐,其助熔共晶效应导致灰熔融温度大幅降低,加剧结渣。Na_(2)SO_(4) is the important intermediate substance that exacerbates the fouling and slagging characteristics of high-alkali coal-fired boilers. The study aims at clarifying the solid-phase deposition and conversion characteristics at high temperature of Na_(2)SO_(4) as well as its effect on ash fusibility in the furnace. Gas phase reaction kinetics was used to study the formation of Na_(2)SO_(4)(g). Deposition and conversion characteristics of Na_(2)SO_(4) at different temperature in the slag layers were summarized. High-temperature conversion of Na_(2)SO_(4) and its effect on ash fusibility were analyzed by experiments on ash fusion temperature and high-temperature mineral conversion. The results show that gas-phase Na primarily presents in Na_(2)SO_(4)(g). A large amount of Na_(2)SO_(4)(g) condenses and deposits at below 900 ℃, and Na_(2)SO_(4) is stable in slag layers at medium and low temperature. The temperature of slag layers increases in radial direction, thus Na_(2)SO_(4) that deposits in outer layers melts and undergoes mineral conversion at high temperature. Na_(2)SO_(4) in outer slag layers reacts with quartz, corundum and other minerals in fly ash, forming aluminosilicate at high temperature. Albite generates in a large amount at about 1000℃ and nepheline generates when Na_(2)SO_(4) content is high. Albite and nepheline further convert into minerals such as sodium-calcium feldspar, lazurite, hauyne and so on above 1100℃. The low melting temperature and eutectic effect of sodium-containing aluminosilicate converted from Na_(2)SO_(4) lead to a significant decrease in ash fusion temperature, which exacerbates slagging.

关 键 词：Na_(2)SO_(4) 反应动力学 固相沉积 矿物转化 热力学平衡 

分 类 号：TK227[动力工程及工程热物理—动力机械及工程]