Three-Dimensional Numerical Simulation To Firebox Of Ethylene Cracking Furnace

In this paper three-dimensional combustion and pyrolysis reactions in the firebox of E-BA-107 ethylene cracking furnace of Yanshan Petrochemical Corporation were simulated by CFD software FLUENT6．2．Actual cracking furnace geometry was modeled as the computational domain to guarantee prediction. Standard k-εturbulence model, discrete ordinate radiation model (DO) and finite-rate/eddy-dissipation model were used in the simulation. By calculation, combustion characteristics of side wall burners and bottom burners, flue gas in firebox and reactions in reactor tubes were presented in detail. The major contributions are listed below:1．The real model and two reference models of the side wall burner were simulated. By comparison, the results show that the burner with less nozzles can form higher flame peak temperature and produce more NOx; Nozzles angle can affect the dimension of eddies and fluid patterns around burner; The real model can produce less NOx and more high temperature field than two reference models.2．A model with a bottom burner was simulated and the results show that a low pressure field was formed by high speed gas from 3-hole nozzles, the mixture gas of 2-hole nozzles and 5-hole nozzle converge to this field, then combustion reaction occur above this region.3．By coupled calculation with combustion in firebox and reactions in reactor tubes the flue gas flowing state and cracking products distributions were presented, the results show that flames of bottom burners and side wall burners make the walls temperature field uniform, which supply nearly equal radiation heat to reactor tubes; Temperature around bottom tubes is lower than that of other parts; Vortices brought about by high gas flows of bottom burners can supply convective heat to reactors tubes.4．Temperature distribution is uniform along the axial and ambient walls of reactor tubes, In reactor tubes the cracking products distribute along axial and radial positions of tubes, meanwhile there was apparent difference to fluid parameters at corresponding position of two group reactor tubes.