-
摘要: 提出了煤灰不均匀熔融概念,有助于解决灰熔融性测定结果和锅炉实际情况不符的问题。采用山西晋城煤,将其粉磨到工业煤粉细度,通过浮沉分成不同密度级别子样,使用灰锥法测定其在弱还原气氛下的熔融温度,使用压降法测量其烧结温度,采用XRD、XRF、SEM-EDX等分析手段对灰样的不均匀熔融现象进行机理研究。结果表明,晋城煤灰软化温度为1501℃,而不同密度级别子样发生分化,软化温度从1292℃到高于1600℃变化;同样,晋煤煤灰烧结温度为885℃,子样的烧结温度从833到943℃变化。机理研究表明,不同密度级别子样Al2O3、Fe2O3和SO3含量发生不均匀分布,是造成煤灰熔融特性和烧结特性差异的根本原因。Abstract: According to the contradiction between ash melting theory and practice, an uneven melting theory was proposed. A typical Jincheng coal from Shanxi, China, was selected, which was ground into the particle size similar to the industrial use. It was separated into different density fractions through float and sink tests, and its chemical composition and mineral composition were analyzed with XRF and XRD, respectively. Ash fusion temperatures (AFTs) under light reducing atmosphere and the pressure-drop temperature(PDT) were tested. SEM-EDX was also employed to observe the melting behavior. It is found that the softening temperature of Jincheng coal is 1501℃, while that of its density fractions changes from 1292℃ to 1600℃. The sintering temperature changes from 833℃ to 943℃, while that of the raw coal ash was 885℃. The study of mechanism shows that the difference of melting and sintering behaviors is caused by the segregation of chemical composition in different density samples, mainly Al2O3, Fe2O3 and SO3.
-
Key words:
- Jincheng coal /
- density fraction /
- ash melting behavior /
- slagging
-
表 1 晋城煤的工业分析和元素分析
Table 1 Proximate and ultimate analysis of Jincheng coal
Proximate analysis w/% Ultimate analysis wdaf/% Qgr, ad/(kJ·kg-1) Mad Ad Vd C H N S O* 4.49 19.24 7.78 71.56 2.62 0.9 3.18 21.74 20467 *:by difference 表 2 粉煤密度组成和工业分析
Table 2 Density composition of pulverized Jincheng coal and their proximate analyses
Sample Density
ρ/(kg·cm-3)Content
w/%Proximate analysis w/% Mad Ad Vdaf JC1 ≤ 1.60 37.51 1.01 6.27 6.84 JC2 1.60-1.70 27.39 1.33 14.39 10.76 JC3 1.70-1.80 16.15 1.25 21.64 14.21 JC4 1.80-2.00 14.31 1.25 35.61 20.19 JC5 >2.00 4.64 0.81 65.65 35.72 表 3 晋城煤及其不同密度级别样品灰化学组成
Table 3 Ash composition analyses of pulverized Jincheng coal and its density fractions
Sample Content w/% K2O Na2O SiO2 Al2O3 CaO MgO SO3 TiO2 P2O5 Fe2O3 JC 0.96 0.18 47.50 33.05 3.07 1.12 2.20 1.17 0.058 8.39 JC1 1.01 0.25 49.23 36.21 2.96 1.40 0.60 1.00 0.060 5.72 JC2 1.00 0.22 48.52 36.74 2.56 1.14 0.72 1.10 0.061 5.34 JC3 1.00 0.23 49.84 34.57 2.83 1.10 0.78 0.86 0.060 5.56 JC4 1.04 0.20 49.08 33.91 3.18 1.16 1.82 1.07 0.056 6.18 JC5 0.69 0.06 43.09 24.45 4.28 0.95 4.34 1.02 0.047 18.99 表 4 JC和JC1的元素组成(EDX)
Table 4 Element composition of JC and JC1 (EDX)
Element content w/% C O Mg Al Si K Ca Ti Fe JC 1 8.55 41.87 0.29 28.92 14.06 0.47 1.77 0.31 3.75 2 12.31 43.03 0.35 14.84 19.2 0.55 3.1 0.51 6.11 3 13.95 49.14 0.11 18.04 14.39 0.95 1.09 0.39 1.94 4 20.16 50.7 0.09 12.4 11.26 0.82 1.07 0.69 2.81 mean value 13.74 46.19 0.21 18.55 14.73 0.7 1.76 0.48 3.65 JC1 1 25.95 40 0.58 17.23 12.22 0.67 1.25 0.67 1.43 2 11.85 49.27 0.28 19.83 12.86 0.53 1.67 1.02 2.7 3 24.36 42.51 0.8 17.92 9.38 0.61 1.97 0.37 1.6 4 14.41 46.4 0.79 19.48 12.43 0.73 2.09 0.59 2.22 mean value 19.14 44.55 0.61 18.62 11.72 0.64 1.75 0.66 1.99 -
[1] BARTELS M, LIN W, NIJENHUIS J. Agglomeration in fluidized beds at high temperatures:Mechanisms, detection and prevention[J]. Prog Energy Combust Sci, 2008, 34(5):633-666. doi: 10.1016/j.pecs.2008.04.002 [2] 李风海, 黄戒介, 房倚天, 王洋.晋城无烟煤流化床气化结渣机理的探索[J].太原理工大学学报, 2010, 41(5):666-669. http://www.wenkuxiazai.com/doc/522894ceaa00b52acfc7caf5.htmlLI Feng-hai, HUANG Jie-jie, FANG Yi-tian, WANG Yang. Exploration on slagging mechanism of Jincheng anthracite during fluidized-bed gasification[J]. J Taiyuan Univ Technol, 2010, 41(5):666-669. http://www.wenkuxiazai.com/doc/522894ceaa00b52acfc7caf5.html [3] 周永刚, 范建勇, 李培, 王炳辉, 赵虹.高碱金属准东煤结渣特性试验[J].浙江大学学报(工学版), 2014, 48(11):2061-2065. http://www.cnki.com.cn/Article/CJFDTOTAL-ZDZC201411021.htmZHOU Yong-gang, FAN Jian-yong, LI Pei, WANG Bing-hui, ZHAO Hong. Slagging characteristics of high alkalis Zhundong coal[J]. J Zhejiang Univ(Eng Sci), 2014, 48(11):2061-2065. http://www.cnki.com.cn/Article/CJFDTOTAL-ZDZC201411021.htm [4] YU D, XU M, SUI J. Effect of coal particle size on the proximate composition and combustion properties[J]. Thermochim Acta, 2005, 439(1/2):103-109. https://www.sciencedirect.com/science/article/pii/S0040603105004867 [5] 刘小伟, 姚洪, 蔡攸敏, 于敦喜, 周科, 徐明厚.煤粉密度对燃煤过程中颗粒物形成特性的影响[J].化工学报, 2007, 58(10):2567-2572. doi: 10.3321/j.issn:0438-1157.2007.10.026LIU Xiao-wei, YAO Hong, CAI You-min, YU Dun-xi, ZHOU Ke, XU Ming-hou. Effect of density fractionation on formation characteristics of particulate matter during coal combustion[J]. J Chem Ind Eng(China), 2007, 58(10):2567-2572. doi: 10.3321/j.issn:0438-1157.2007.10.026 [6] 蔡攸敏, 姚洪, 刘小伟, 徐明厚.不同密度煤粉的矿物质分布与燃烧特性研究[J].热能动力工程, 2007, 22(6):651-655. https://www.wenkuxiazai.com/doc/af5a64f90975f46527d3e1e1.htmlCAI You-min, YAO Hong, LIU Xiao-wei, XU Ming-hou. A study of the mineral distribution and combustion characteristics of pulverized coal of different densities[J]. J Eng Therm Energy Power, 2007, 22(6):651-655. https://www.wenkuxiazai.com/doc/af5a64f90975f46527d3e1e1.html [7] VAN DYK J C, BENSON S A, LAUMB M L. Coal and coal ash characteristics to understand mineral transformations and slag formation[J]. Fuel, 2009, 88(6):1057-1063. doi: 10.1016/j.fuel.2008.11.034 [8] WU L, XU M H, WANG S F. Study of different densities pulverized coal combustion characteristics under O2/CO2 atmosphere[J]. J Eng Therm, 2010, 31(10):1789-1792. https://www.scientific.net/amm.229-231.2804.pdf [9] ZHANG H, MO Y, SUN M. Determination of the mineral distribution in pulverized coal using densitometry and laser particle sizing[J]. Energy Fuels, 2005, 19(6):2261-2267. doi: 10.1021/ef050201u [10] 张洪, 胡光洲, 范佳鑫, 蒲文秀, 莫言学, 哈斯, 李迎.矿物在煤粉中的分布规律研究[J].工程热物理学报, 2008, 29(7):1231-1235. https://www.wenkuxiazai.com/doc/9d832ee02cc58bd63086bd0a-2.htmlZHANG Hong, HU Guang-zhou, FANG Jia-xin, PU Wen-xiu, MO Yan-xue, HA Si, LI Ying. Study on the distribution of minerals in pulverized coals[J]. J Eng Therm, 2008, 29(7):1231-1235. https://www.wenkuxiazai.com/doc/9d832ee02cc58bd63086bd0a-2.html [11] 郝娟, 张洪, 陈佳宝, 李亚男.工业混煤煤粉中矿物质分布规律[J].浙江大学学报工学版, 2012, 46(4):756-763. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zdzc201204027&dbname=CJFD&dbcode=CJFQHAO Juan, ZHANG Hong, CHEN Jia-bao, LI Ya-nan. Mineral distribution of industry blended coal powder[J]. J Zhejiang Univ(Eng Sci), 2012, 46(4):756-763. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zdzc201204027&dbname=CJFD&dbcode=CJFQ [12] ALOTOOM A Y, BRYANT G W, ELLIOTT L K. Experimental options for determining the temperature for the onset of sintering of coal ash[J]. Energy Fuels, 1999, 14(1):41. https://www.researchgate.net/publication/231275519_Experimental_Options_for_Determining_the_Temperature_for_the_Onset_of_Sintering_of_Coal_Ash [13] SONG W J, TANG L H, ZHU X D. Effect of coal ash composition on ash fusion temperatures[J]. Energy Fuels, 2010, 24(1):182-189. doi: 10.1021/ef900537m [14] 程相龙, 王永刚, 张荣, 毕继诚.低温共熔物对煤灰熔融温度影响的研究[J].燃料化学学报, 2016, 44(9):1043-1050. http://manu60.magtech.com.cn/rlhxxb/CN/abstract/abstract18891.shtmlCHENG Xiang-long, WANG Yong-gang, ZHANG Rong, BI Ji-cheng. Effect of low temperature eutectics on coal ash fusion temperatures[J]. J Fuel Chem Technol, 2016, 44(9):1043-1050. http://manu60.magtech.com.cn/rlhxxb/CN/abstract/abstract18891.shtml [15] LI J, ZHU M, ZHANG Z. Effect of coal blending and ashing temperature on ash sintering and fusion characteristics during combustion of Zhundong lignite[J]. Fuel, 2017, 195:131-142. doi: 10.1016/j.fuel.2017.01.064 [16] 代百乾, 乌晓江, 张忠孝.高碱煤燃烧过程中灰中主要元素的迁移规律[J].动力工程学报, 2014, 34(6):438-442. http://www.cqvip.com/QK/95606A/201406/68797871504849524854484853.htmlDAI Bai-qian, WU Xiao-jiang, ZHANG Zhong-xiao. Transition behavior of main elements in fly ash during high alkali coal combution[J]. Chin J Power Eng, 2014, 34(6):438-442. http://www.cqvip.com/QK/95606A/201406/68797871504849524854484853.html [17] SCHEPPER M D, HEEDE P V D, ARVANITI E C. Sulfates in completely recyclable concrete and the effect of CaSO4 on the clinker mineralogy[J]. Constr Build Mater, 2017, 137:300-306. doi: 10.1016/j.conbuildmat.2017.01.127