Modeling of a multizone gas‐phase polyethylene reactor with a cluster‐based approach

Abstract

A circulating fluidized reactor of polyethylene was modeled with the proper hydrodynamics for a riser and downer and combined with a kinetic model based on the moment equations. The hydrodynamic model was able to predict the profiles of the following parameters through the riser and downer: cluster velocity, bed porosity, concentration of potential active sites, active sites, gas-phase components, molecular weights, and reactor temperature. It was shown that one could control the monomer consumption and molecular weight, which are crucial in the reactor behavior and production properties, respectively, by setting different operating hydrodynamic conditions, such as the gas velocity in the riser and the solid circulation rate.

Multiscale modelling of multizone gas phase propylene (co)polymerization reactors—A comprehensive review

“…[ 11 ] This can be done if some reactions are very fast or very slow (e.g., assume instantaneous catalyst activation, negligible deactivation during its residence time, etc. ). Single‐site kinetic model [ 15,44,46,47,130 ] ; the multiple active sites of the ZN catalyst are lumped together into a single active site. This approach may offer a good prediction of the polymerization rate and polymer MWD if the difference between the activities of the different sites is small, otherwise, it cannot be used.…”

“…• Site activation [46] PE (LLDPE) (ethylene/1-butene) [47,48] PE (LLDPE) (ethylene/1-butene) [14,15] PP (HPP and RCP) (propylene/ ethylene) [49] PP-HPP (propylene) [51] PP-HPP and ICP (propylene/ ethylene)…”

“…Adli et al [46] improved the steady-state model of Fernandez and Lona [44,45] by treating the moving solid particles as clusters rather than individual particles. They made it clear that the formation of clusters highly influences the hydrodynamics and cannot be neglected in the MZCR.…”

“…2. Single-site kinetic model [15,44,46,47,130] ; the multiple active sites of the ZN catalyst are lumped together into a single active site. This approach may offer a good prediction of the polymerization rate and polymer MWD if the difference between the activities of the different sites is small, otherwise, it cannot be used.…”

Hydrodynamic design of multi‐zone circulating reactors using CFD

“…Although several attempts have been reported on modelling and simulation of CFBs, there are few reports on modelling and simulation of MZCRs. Adli et al applied a cluster‐based approach to model polymerization in a MZCR. They determined the profiles of gas velocity, porosity, cluster velocity, temperature, and concentration along the reactor.…”