管道式分解炉中褐煤燃烧耦合CaCO_3分解的数值模拟
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摘要
以某水泥厂管道式分解炉为研究对象,采用CFD数值模拟方法,选取合适的数学模型,模拟分析褐煤在此分解炉系统中的流场特性、煤粉燃烧特性及煤粉燃烧耦合情况下碳酸钙分解情况。模拟结果表明:从分解炉锥体切向而来的三次风与来自窑尾缩口向上运动的高速烟气流相遇后,汇合成一股高速向上运动的主气流,煤粉流与生料流随着主气流在分解炉中心处向上螺旋式运动;煤粉的燃烧主要发生在分解炉下半柱体与锥体交界附近,并形成了高温区,且燃烧区域右侧燃烧情况优于左侧;在分解炉下柱体下半区域,碳酸钙迅速分解。在不进行SNCR脱硝处理的情况下,分解炉出口处NO含量仅为246. 81 ppm,完全达到国家规定水平。
Taking a pipeline precalciner of a certain cement plant as the research object,the CFD numerical simulation method was used to select the appropriate mathematical model to simulate and analyze the flow field characteristic,coal dust combustion characteristic of lignite in this precalciner system,and the decomposition situation of calcium carbonate under the circumstance of combustion and coupling of pulverized coal. The simulation results show that after the tertiary air tangentially from the precalciner cone meets the high-velocity flue gas flow moving upwards from the kiln inlet necking down,a main airflow which moves upward with high velocity could be converged,pulverized coal flow and raw material flow would spirally move upward following the main airflow in the center of the precalciner. The combustion of pulverized coal mainly occurs near the junction of the lower half cylinder of the decomposition furnace and the cone,then a high temperature zone is formed; and the combustion condition on the right side of combustion zone is superior to the left side. In the lower half of the precalciner's lower cylinder,calcium carbonate rapidly decomposes. Under the circumstance that SNCR denitrification treatment is not conducted,the NO content at the precalciner outlet is only 246. 81 ppm,fully meets the level that state prescribes.
Taking a pipeline precalciner of a certain cement plant as the research object,the CFD numerical simulation method was used to select the appropriate mathematical model to simulate and analyze the flow field characteristic,coal dust combustion characteristic of lignite in this precalciner system,and the decomposition situation of calcium carbonate under the circumstance of combustion and coupling of pulverized coal. The simulation results show that after the tertiary air tangentially from the precalciner cone meets the high-velocity flue gas flow moving upwards from the kiln inlet necking down,a main airflow which moves upward with high velocity could be converged,pulverized coal flow and raw material flow would spirally move upward following the main airflow in the center of the precalciner. The combustion of pulverized coal mainly occurs near the junction of the lower half cylinder of the decomposition furnace and the cone,then a high temperature zone is formed; and the combustion condition on the right side of combustion zone is superior to the left side. In the lower half of the precalciner's lower cylinder,calcium carbonate rapidly decomposes. Under the circumstance that SNCR denitrification treatment is not conducted,the NO content at the precalciner outlet is only 246. 81 ppm,fully meets the level that state prescribes.
引文
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[16]嵇鹰,田耀鹏,徐德龙.水泥工业NO_X排放控制探讨[J].西安建筑科技大学学报(自然科学版),2009,41(3):397-403.
[2]刘宏宇.试述研究劣质褐煤加工提质技术(典型工艺)[J].工程技术:全文版,2016(8):132.
[3]李春柱.维多利亚褐煤科学进展(精)[M].北京:化学工业出版社,2009.
[4]戴和武,谢可玉.褐煤利用技术[M].北京:煤炭工业出版社,1999.
[5]滕英跃,赵畅,刘全生,等.褐煤中矿物质对水泥熟料烧成过程的影响[J].硅酸盐通报,2014,33(2):236-242.
[6]贺继荣.褐煤代替部分烟煤煅烧水泥熟料的尝试[J].水泥技术,2011(6):84-85.
[7]张三梅. DD分解炉分级燃烧减排NOx的数值模拟及优化研究[D].武汉:武汉理工大学,2012.
[8]黄来,陆继东,李昌军,等.双喷腾分解炉内气固两相流场的数值模拟[J].硅酸盐学报,2003,31(8):748-753.
[9]梅书霞,谢峻林,何峰,等. DD分解炉燃烧与分解耦合过程的数值模拟[J].化工学报,2013,64(3):897-905.
[10]丁历威,李凤瑞. Fluent软件模拟计算煤粉燃烧的机理及其模型实现的方式[J].浙江电力,2010,29(11):31-34.
[11] Chen L,Ghoniem A F. Development of a three-dimensional computational slag flow model for coal combustion and gasification[J]. Fuel,2013,113(2):357-366.
[12] Li Z Q,Wei F,Jin Y. Numerical simulation of pulverized coal combustion and NO formation[J]. Chemical Engineering Science,2003,58(23):5161-5171.
[13]丁苏东,孙德群,蔡玉良.低NO_X型分解炉内部过程的数值模拟研究[J].中国水泥,2007(4):46-50.
[14]陶从喜,彭学平,胡芝娟,等. TWD型分解炉的研究开发及工程应用[J].水泥,2007(4):25-27.
[15]任合斌,陆继东,胡芝娟,等.水泥回转窑内NO生成及其分布规律研究[J].工程热物理学报,2006,27(s2):159-162.
[16]嵇鹰,田耀鹏,徐德龙.水泥工业NO_X排放控制探讨[J].西安建筑科技大学学报(自然科学版),2009,41(3):397-403.