Nonlinear Multivariable Control of Product Properties in an Industrial Gas Phase Polyethylene Reactor

A nonlinear model-based scheme is developed for product property control in industrial gas phase polyethylene reactors. The controller is designed for instantaneous melt index and density regulation over a range of products, and for control during grade changeovers. The feedback controller manipulates the hydrogen and butene feed rates to force the product properties to follow a desired trajectory. During grade changeovers, these trajectories …