Numerical Simulation Of Combustion,Flow,Heat Transfer And Cracking Reaction In Cracking Furnace

Ethylene industry is a symbol of nation petrochemical development level,cracking furnace is the most important equipment of ethylene industry.Cracking furnace is a high energy-consuming equipment.There is complicated combustion,flow,heat transfer and cracking reaction in cracking furnace.Studying processes in cracking furnace is of great importance to design and optimize furnace.On the basis of studying the history,present situation and trend of cracking furnace at home and abroad,numerical simulation is used to comprehensive analysis the fuel combustion,smoke flow in furnace and the cracking reaction,flow in tube:(1)The Kumar reaction kinetics model which has 22 reactions,EDC model,k-? turbulence model are used to describe the cracking,flow,heat transferring process in U tube.The basic law of flow and cracking reaction in tube are revealed by analyzing velocity,temperature,pressure and concentration of gas in tube.(2)Mathematical model of USC(W)cracking furnace has been established with non-premixed PDF model,DO model,k-? model in furnace and Kumar model,EDC model,k-? model in tube.Coupled heat transfer between furnace and tube is calculated by iteration method.The result of numerical simulation tallies well with industrial data so that the mathematical model is proved to be accurate.The result shows that flow field,temperature,concentration of fuel and oxygen in furnace influence each other and distribute unevenly which cause the temperature of tube changes along XY direction of furnace.(3)Based the characteristics of flow and temperature distribution in furnace and the influence to ethylene mass fraction,a new improved structure scheme is proposed in this paper.The temperature of furnace top is higher than the customary structure.The heat transfer of tube increases and radiation efficiency is improved.The new structure provides a new way of thinking for optimal design of cracking furnace.