采用数值模拟研究不同供热形式对裂解炉运行的影响

利用计算流体力学Fluent软件,选择标准k-ε湍流模型、有限速率/涡耗散燃烧模型和P1辐射模型等计算模型,对全部由底部燃烧器供热(简称全底烧供热)和由底部和侧壁燃烧器联合供热(简称联合供热)的工况进行三维数值模拟计算,得到了底部燃烧器喷口面、炉管位置中心面、横跨段出口面烟气温度分布以及炉管管壁温度分布和烟气组成分布的数据。模拟计算结果表明,全底烧供热时炉膛底部形成高温区,炉膛上部温度低;联合供热时在炉膛上方采用侧壁燃烧器补充热量,炉膛烟气温度场比全底烧供热更加适合于管内的烃类裂解反应,联合供热时炉管管壁温度分布优于全底烧供热;全底烧供热时横跨段出口面烟气温度平均值高于联合供热。

Study of Effect of Heat Release Mode on Running of Cracking Furnace by Numerical Simulation

The different heat release modes(combined heating and hearth heating)used in cracking furnaces were simulated by means of standard k-ε turbulence model,finite-rate/eddy-dissipation combustion model and P1 radiation model of the computational fluid dynamics software Fluent.The flue gas temperature distributions of the inlet surface of the hearth burners,the central surface of the tube location and the outlet surface of the crossover section,and the tube metal temperature and the flue gas composition were obtained through the stimulation.The simulation results showed that the hearth heating could come into higher temperature in the bottom zone of cracking furnace and lower temperature in the upside than the combined heating.As the heat supplement of wall burners in the combined heating,the flue gas temperature field is more compatible with the cracking reactions in the tubes than that in the hearth heating and the distribution of tube metal temperature is more appropriate for cracking of the hydrocarbons.The flue gas average temperature of the crossover section outlet in the hearth heating is higher than that in the combined heating.