Computational Fluid Dynamic design of steam cracking reactors: extrusion method for simulation of dynamic coke layer growth

摘要

Computational fluid dynamics (CFD) gas been successfully applied for the evaluation of the start-of-run performance of three-dimensional (3D) coil geometries in steam cracking reactors. However, as the most attractive characteristic of these 3D coil geometries is the potential extension of the run length, determining the full economic potential of a coil involves tracking its performance throughout the run and not only at start-of-run. In the case of 3D tubular geometries, the growth of the coke layer will generally not be uniform. Because of this, the reactor geometry will change in time, which will in turn influence the fluid dynamics, product yields and successive coke formation. To take this into account, the coke layer growth needs to be incorporated in the CFD simulations. In this work an algorithm based on dynamic meshing will be discussed for simulating coke formation on the 3D reactor geometry and tracking the geometry deformation caused by the growing coke layer. As a proof-of-concept, a Millisecond propane cracker was simulated over the first days of its run length for a bare tube and a classically applied finned reactor design. Future work also includes comparison with other industrially relevant 3D reactor geometries.