准东地区粉煤灰改性做高碱煤缓焦剂的熔融性能评估
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摘要
准东煤高含量碱金属引起的严重结渣和沾污问题已引起了广泛关注。目前电站锅炉大多采用添加高岭土的方式来缓解结渣,但由于高岭土成本较高,以及当地大量粉煤灰无法处理,因此提出将粉煤灰处理后用作高碱煤缓焦剂。本文针对粉煤灰缓焦剂的熔融特性进行评估,并采用X射线荧光光谱分析(XRF)和X射线衍射分析(XRD)对不同处理方式下的粉煤灰进行分析,获得其熔点发生变化的原因。结果表明:不同粒径下的原粉煤灰熔点基本相同,经过水洗后的粉煤灰在中等粒径下熔点升高仅30℃左右,而<37μm和>100μm的粉煤灰经过水洗后不变;酸洗粉煤灰后>100μm的粉煤灰熔点升高超过100℃,而其他处理方式下的粉煤灰熔点基本不变;>100μm的粉煤灰主要来源于外来矿物和添加的高岭土,经过酸洗,Na和Ca的氧化物或无机盐溶于盐酸,使灰中SiO2含量大幅度升高,进而使灰熔点升高。
The serious slagging and fouling problems caused by high alkali content in Zhundong coal has drawn wide attentions. At present, most of the power plants add kaolin in Zhundong coal to remit the slagging problems.However, the economy of this method reduces due to the high price of kaolin. On the other hand, large quantities of fly ash in Zhundong coal are unavailable for treatment. So the fly ash is proposed to use as slagging inhibitor for coals with high alkali metal content. This study evaluates the fusion characteristics of the slagging inhibitor,and analyzes the fly ash treated by different ways via X-ray fluorescence spectrum analysis(XRF) and X-ray diffraction analysis(XRD). The reason of fusion points variation was determined. The results indicated that, the fusion points of the raw fly ash with different sizes were basically identical. The fusion points of the fly ash(37～100 μm) increased by only 30 ℃ after water-washing, while that of the other fly ashes(<37 μm and >100 μm)almost unchanged. After the fly ash was washed by acid, the fusion points of large particles(>100 μm) increased by over 100 ℃, while the fusion temperatures variation of the small particles was inconspicuous. The largeparticles(>100 μm) in fly ash mainly came from the foreign minerals and the Kaolin additives. After the fly ash was washed by acid, the alkali and alkaline metal adhered on the surface of the particles was removed into the acid solution, causing significant increase in SiO_2 proportion in the ash, so the fusion points increased.
The serious slagging and fouling problems caused by high alkali content in Zhundong coal has drawn wide attentions. At present, most of the power plants add kaolin in Zhundong coal to remit the slagging problems.However, the economy of this method reduces due to the high price of kaolin. On the other hand, large quantities of fly ash in Zhundong coal are unavailable for treatment. So the fly ash is proposed to use as slagging inhibitor for coals with high alkali metal content. This study evaluates the fusion characteristics of the slagging inhibitor,and analyzes the fly ash treated by different ways via X-ray fluorescence spectrum analysis(XRF) and X-ray diffraction analysis(XRD). The reason of fusion points variation was determined. The results indicated that, the fusion points of the raw fly ash with different sizes were basically identical. The fusion points of the fly ash(37～100 μm) increased by only 30 ℃ after water-washing, while that of the other fly ashes(<37 μm and >100 μm)almost unchanged. After the fly ash was washed by acid, the fusion points of large particles(>100 μm) increased by over 100 ℃, while the fusion temperatures variation of the small particles was inconspicuous. The largeparticles(>100 μm) in fly ash mainly came from the foreign minerals and the Kaolin additives. After the fly ash was washed by acid, the alkali and alkaline metal adhered on the surface of the particles was removed into the acid solution, causing significant increase in SiO_2 proportion in the ash, so the fusion points increased.
引文
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[11]韩怀强,蒋挺大.粉煤灰利用技术[M].北京:化学工业出版社,2001:18-23.HAN Huaiqiang,JIANG Tingda.Utilization technology of fly ash[M].Beijing:Chemical Industry Press,2001:18-23.
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[13]BRYERS R W.Fireside slagging,fouling,and high-temperature corrosion of heat-transfer surface due to impurities in steam-raising fuels[J].Progress in Energy and Combustion Science,1996,22(1):29-120.
[14]刘敬,王智化,项飞鹏,等.准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究[J].燃料化学学报,2014,42(3):316-322.LIU Jing,WANG Zhihua,XIANG Feipeng,et al.Modes of occurrence and transformation of alkali metals in Zhundong coal during combustion[J].Journal of Fuel Chemistry and Technology,2014,42(3):316-322.
[15]WANG X,XU Z,WEI B,et al.The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium:a study from ash evaporating to condensing[J].Applied Thermal Engineering,2015,80:150-159.
[2]WANG C,XI J,WANG Y,et al.Release and transformation of sodium during pyrolysis of Zhundong coals[J].Journal of the Energy Institute,2016,89(1):48-56.
[3]XU J,YU D,FAN B,et al.Characterization of ash particles from co-combustion with a Zhundong coal for understanding ash deposition behavior[J].Energy&Fuels,2012,28(1):678-684.
[4]陶玉洁,张彦威,周俊虎,等.准东煤在燃烧过程中的矿物演变过程及Na、Ca释放规律[J].中国电机工程学报,2015,35(5):1169-1175.TAO Yujie,ZHANG Yanwei,ZHOU Junhu,et al.Mineral conversion regularity and release behavior of Na,Ca during Zhundong coal’s combustion[J].Proceedings of the CSEE,2015,35(5):1169-1175.
[5]孟建强.准东煤燃烧及结渣特性研究[D].哈尔滨:哈尔滨工业大学,2013:32-38.MENG Jianqiang.Research on combustion and slagging characteristics of Zhundong coal[D].Harbin:Harbin Institute of Technology,2013:32-38.
[6]周永刚,范建勇,李培,等.高碱金属准东煤灰熔融过程的矿物质衍变[J].浙江大学学报(工学版),2015,49(8):1559-1564.ZHOU Yonggang,FAN Jianyong,LI Pei,et at.Mineral transmutation of high alkali Zhundong coal in ash melting process[J].Journal of Zhejiang University(Engineering Science),2015,49(8):1559-1564.
[7]马岩,黄镇宇,唐慧儒,等.准东煤灰化过程中的矿物演变及矿物添加剂对其灰熔融特性的影响[J].燃料化学学报,2014,42(1):20-25.MA Yan,HUANG Zhenyu,TANG Huiru,et al.Mineral conversion of Zhundong coal during ashing process and the effect of mineral additives on its ash fusion characteristics[J].Journal of Fuel Chemistry and Technology,2014,42(1):20-25.
[8]沈铭科,邱坤赞,黄镇宇,等.准东煤掺烧高岭土对固钠率及灰熔融特性影响研究[J].燃料化学学报,2015,43(9):1044-1051.SHEN Mingke,QIU Kunzan,HUANG Zhenyu,et al.Influence of kaolin on sodium retention and ash fusion characteristic during combustion of Zhundong coal[J].Journal of Fuel Chemistry and Technology,2015,43(9):1044-1051.
[9]WEI B,WANG X B,TAN H Z,et al.Effect of silicon-aluminum additives on ash fusion and ash mineral conversion of Xinjiang high-sodium coal[J].Fuel,2016,181:1224-1229.
[10]王学斌,魏博,张利孟,等.温度和SiO2添加物对准东煤中碱金属的赋存形态及迁徙特性的影响[J].热力发电,2014,43(8):84-88.WANG Xuebin,WEI Bo,ZHANG Limeng,et al.Effect of temperature and silicon additives on occurrence and transformation characteristics of alkali metal in Zhundong coal[J].Thermal Power Generation,2014,43(8):84-88.
[11]韩怀强,蒋挺大.粉煤灰利用技术[M].北京:化学工业出版社,2001:18-23.HAN Huaiqiang,JIANG Tingda.Utilization technology of fly ash[M].Beijing:Chemical Industry Press,2001:18-23.
[12]李文.煤的灰化学[M].北京:科学出版社,2013:55-58.LI Wen.Chemistry of ash from coal[M].Beijing:Science Press,2013:55-58.
[13]BRYERS R W.Fireside slagging,fouling,and high-temperature corrosion of heat-transfer surface due to impurities in steam-raising fuels[J].Progress in Energy and Combustion Science,1996,22(1):29-120.
[14]刘敬,王智化,项飞鹏,等.准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究[J].燃料化学学报,2014,42(3):316-322.LIU Jing,WANG Zhihua,XIANG Feipeng,et al.Modes of occurrence and transformation of alkali metals in Zhundong coal during combustion[J].Journal of Fuel Chemistry and Technology,2014,42(3):316-322.
[15]WANG X,XU Z,WEI B,et al.The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium:a study from ash evaporating to condensing[J].Applied Thermal Engineering,2015,80:150-159.