Coke combustion and gasification kinetics in ethane steam crackers

Simulation of the decoking of an ethane cracker with a steam/air mixture

“…On the other hand, the reactor diameter grows as a function of time due to the disappearance of the coke layer. Heynderickx et al (2005).…”

“…By regression of experimental data, the parameter values have been estimated. The parameter estimation and model discrimination resulted in the following intrinsic rate equation for process gas side coke combustion: Schools (2002) and Heynderickx et al (2005) showed that for coke combustion internal mass and heat transport limitations are to be considered, while they are completely negligible for coke gasification. …”

“…The effective diffusivities are calculated as explained by Heynderickx et al (2005). The effective diffusivity of oxygen is of the order of 4 × 10 −6 m −3 f m −1 p s −1 .…”

“…Carbon oxide immediately reacts with oxygen to form carbon dioxide in a homogeneous gas phase reaction, as discussed by Heynderickx et al (2005). An adequate gas-solid reaction/diffusion model and an adequate texture model are also part of a complete reactor model (Heynderickx et al, 2005). Furthermore, the reactor model needs to be coupled to a furnace model describing the radiative and convective heat transfer from the flue gases and the furnace walls to the reactor coils.…”

“…The heterogeneous combustion of coke to form carbon oxide can be neglected. Carbon oxide immediately reacts with oxygen to form carbon dioxide in a homogeneous gas phase reaction, as discussed by Heynderickx et al (2005). An adequate gas-solid reaction/diffusion model and an adequate texture model are also part of a complete reactor model (Heynderickx et al, 2005).…”