Modeling and Simulation of Liquid Phase Propylene Polymerizations in Industrial Loop Reactors

Abstract

Summary: Liquid phase tubular loop polymerization reactors are widely used in the polyolefin industries because of their capabilities to promote high mixing of reactants in the reaction vessel and to allow for high heat transfer rates with the cooling jacket due to their high aspect ratio. Previous works on this subject focused on the modeling of the polymerization system, but only a few compared their results with real industrial data. A literature review about the propylene production in loop reactors shows that the validation of a distributed model with actual industrial data is yet to be presented. A distributed mathematical model is presented for industrial liquid phase loop polypropylene reactors and validated with actual industrial data for the first time. The model is able to represent the dynamic trajectories of production rates, MFI and XS values during grade transitions within the experimental accuracy. The model indicates that the polymer quality can change significantly along the reactor train and that manipulation of feed flow rates can be successfully used for production of more homogeneous polymer products.

A dynamically distributed reactor model for identifying the flow fields in industrial loop propylene polymerization reactors

“…On the other hand, there are many published papers relating to the loop polymerization reactor (R200, R201 or R202) 2, 3, 30–33, 39, 41, 46, 47. As reported in previous works,30–32 the loop reactor consists essentially of a main tubular system closed in a loop (see Figure 1).…”

“…The energy conservation is obtained by neglecting energy changes due to expansion work, viscous flow, external fields, radiation, and heat of mixing, which is applied in previous works 30, 31, 33–37, 48. The differential equation of energy in one spatial dimension can be written as: …”

“…In their work, polymer moment balances were used to compute resin properties, such as average molecular weights, polydispersity, and melt flow index, but no reactor pressure and mass velocity data were reported. Pinto et al33 presented a dynamically distributed model with a recycle pump in the loop PP reactors and validated with industrial data for the first time based on their previous works 34–37. The model was able to predict the dynamic trajectories of production rates, melt flow index, and xylene soluble values during grade transitions within the experimental accuracy 38.…”

“…The model was able to predict the dynamic trajectories of production rates, melt flow index, and xylene soluble values during grade transitions within the experimental accuracy 38. Although their model was a distributed model and could predict some variable distributions in loop reactors, there were still no distributed pressure and mass velocity data due to the absences of state‐equation and momentum conservation equation in their works 33–37. Recently, Touloupides et al1 developed a comprehensive dynamical mathematical model to describe the dynamic operation of an industrial slurry‐phase ethylene‐1‐hexene copolymerization loop reactor series based on dynamical macroscopic mass and energy conservations for each loop reactor and validated with industrial data.…”

Comprehensive Study of Reactants Depletion in Catalytic Olefin Polymerization Industrial Loop Reactors

“…De Lucca et al, 24 presented a distributed mathematical model for a series of slurry-phase loop polypropylene reactors which was validated with actual industrial data. They pointed out that model was capable of simulating a train of loop reactors with multiple feeds located at the inlet of each reactor of the configuration.…”