化工进展 ›› 2020, Vol. 39 ›› Issue (2): 496-505.DOI: 10.16085/j.issn.1000-6613.2019-0921

• 能源加工与技术 • 上一篇    下一篇

碱性氧化物对煤灰熔融特征行为的影响

郑烨1(),李建波2,关彦军1,杨凤玲3,张锴1(),程芳琴3   

  1. 1.华北电力大学热电生产过程污染物监测与控制北京市重点实验室,北京 102206
    2.低品位能源利用技术及系统教育部重点实验室,重庆大学,重庆 400044
    3.山西大学资源与环境工程研究所,国家环境保护煤炭废弃物 资源化高效利用技术重点实验室,山西 太原 030006
  • 收稿日期:2019-06-10 出版日期:2020-02-05 发布日期:2020-03-12
  • 通讯作者: 张锴
  • 作者简介:郑烨(1987—),男,博士研究生,研究方向为煤灰化学。E-mail:1142102039@ncepu.edu.cn
  • 基金资助:
    国家自然科学基金委与陕西煤基低碳联合基金重点项目(U1610254);中央高校基本科研业务费专项(JB2017155)

Effects of basic oxides on ash fusion characteristic of coal ash

Ye ZHENG1(),Jianbo LI2,Yanjun GUAN1,Fengling YANG3,Kai ZHANG1(),Fangqin CHENG3   

  1. 1.Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation, North China Electric Power University, Beijing 102206, China
    2.Key Laboratory of Low-grade Energy Utilization Technologies and Systems of the Ministry of Education of China, Chongqing University, Chongqing 400044, China
    3.Institute of Resources and Environment Engineering, School of Environmental & Resource Sciences, State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Shanxi University, Taiyuan 030006, Shanxi, China
  • Received:2019-06-10 Online:2020-02-05 Published:2020-03-12
  • Contact: Kai ZHANG

摘要:

利用分析纯试剂制备了酸碱比为0.82,但Na2O、CaO、MgO和Fe2O3含量不同的合成灰,并在815℃下在马弗炉中进行灼烧后,对其熔融温度进行测定。同时利用扫描电子显微镜-能谱仪(SEM-EDS)和X射线衍射仪(XRD)对样品微观形貌和矿物组成进行表征。结果表明:随着Na2O质量分数从4%升高到12%,合成灰变形温度(DT)、软化温度(ST)、半球温度(HT)和流动温度(FT)分别从1225℃、1233℃、1255℃和1297℃下降为1162℃、1174℃、1181℃和1189℃,意味着Na2O对合成灰具有较强的助熔效果;随着CaO和MgO含量在合成灰中分别增加,DT、ST和HT均单调上升,而FT则呈先下降后上升趋势,说明二者含量变化与合成灰熔融温度呈非线性关系;随着Fe2O3质量分数由5%增加至30%,FT由1215℃上升至1308℃,而其他3个熔融特征温度并无显著变化。通过SEM-EDS和XRD表征发现,合成灰中耐熔矿物(SiO2和CaAl2Si2O8等)和助熔矿物(CaMgSi2O6和NaAlSiO4等)的比例变化和含钠矿物、含钙矿物之间低温共熔反应程度是影响其熔融温度的主要原因。综合对比所有合成煤灰熔融特征温度和化学组成发现,对于具有相同酸碱比的煤灰,DT主要与样品中Na2O含量和碱土金属总量(CaO+MgO)密切相关影响,而FT主要受Na2O和Fe2O3含量影响。

关键词: 煤灰, 碱性氧化物, 灰熔融温度, 矿物组成, 微观形貌

Abstract:

The fusion characteristics of twenty-three synthetic ashes with the same acidic to basic ratio (Ra/b) of 0.82 but with varying acidic oxides including Na2O, CaO, MgO, and Fe2O3 were investigated. The synthetic ashes were prepared in accordance with the Ra/b of Zhundong coal ash, and then ashed in a muffle furnace at 815℃. These ashes were then subjected to ash fusion analyzer, SEM-EDS and XRD analysis for their fusion temperatures (AFTs), microstructures and mineralogical composition. The results showed that deformation temperature (DT), softening temperature (ST), hemispherical temperature (HT) and flow temperature (FT) of the synthetic ash decreased from 1225℃, 1233℃, 1255℃ and 1297℃, respectively, to 1162°C, 1174℃, 1181℃ and 1189℃ as Na2O content increased from 4% to 12%, indicating that Na2O played a significant role in decreasing AFTs. Likewise, as the CaO and MgO contents increased, DT, ST and HT were decreased, while FT was decreased first but increased afterwards, indicating that the effect of CaO and MgO addition on AFTs were non-linear. Furthermore, significant changes in AFTs were not observed as Fe2O3 mass fraction varied from 5% to 30%, with the exception that FT increased from 1215℃ to 1308℃. SEM-EDS and XRD analysis revealed that the variation in fusion characteristics of the synthetic ashes were mainly attributed to the proportion of refractory minerals mainly SiO2 and CaAl2Si2O8 and the fluxing minerals such as CaMgSi2O6 and NaAlSiO4, as well as the degree of eutectic formation between Na- and Ca- bearing minerals. A comprehensive comparison between the measured AFTs and their corresponding basic oxide contents showed that DT was mainly affected by the overall amount of alkaline-earth metal (CaO and MgO) and Na2O content, whereas FT was closely associated with Na2O and Fe2O contents in the synthetic ash.

Key words: coal ash, basic oxides, ash fusion temperature, mineral composition, micromorphology

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