蓄热式钢包烘烤过程中包内高温低氧特性的数值模拟

Numerical Simulation on High Temperature and Diluted Air Characteristics of Regenerative Ladle Baker

为了分析入炉气体的预热温度对高温空气燃烧过程的影响,综合考虑体系的质量、动量、能量守恒以及燃烧体系的组份平衡,建立了煤气-空气双预热的三维非稳态燃烧数学模型,并以CFX4.3为计算平台,耦合流体流动、燃烧和换热过程,首次对蓄热式燃烧过程中高温低氧特性进行了数值研究,得出了在不同预热温度时,燃烧室内气体温度场和氧气浓度场分布.结果表明,提高气体预热温度有利于加快燃烧进程,提高燃烧室内气体的整体温度及温度均匀性,降低局部氧浓度.

High temperature air combustion (HTAC) can increase the adiabatic flame temperature and enlarge the flame volume, which can strengthen the heating capability. Based on the technology of HTAC, the fuel in regenerative ladle baker can burn completely. The preheated temperature of inlet gases affects the combustion process greatly. With the aim to study the effect of preheated temperature on the combustion, a 3-D transient mathematical model of combustion combined with flow and heat transfer is established in this paper. Based on the commercial CFD soft CFX, using the method of Finite Difference and SIMPLEC, the characteristics of high temperature diluted air in the chamber under different preheating temperatures of inlet gases are analyzed numerically. Turbulence k-e model, Mixed Is Burnt model and Monte Carlo method are used. Results evidence that due to effects of jets, backflow and eddies are formed and the high temperature burned flue gas in the ladle can mix and dilute the fresh air. Higher temperature of inlet gases is favorable to the combustion process. Increasing the preheating temperature can increase the domain temperature and its uniformity and decrease the oxygen content of local flue in the chamber. The deviation of temperature between calculated results and test results is less than 30 K. The calculated results agree with the experimental observation and theoretical analysis well.