管道式分解炉中褐煤燃烧耦合CaCO_3分解的数值模拟

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。

Numerical Simulation of Coupling CaCO3 Decomposition of Lignite Combustion in the Precalciner

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.