Advances in Mathematical Modeling of Gas-Phase Olefin Polymerization

Asia-Pacific J Chem Eng

2020

Dynamic modeling of the polyolefin polymerization process in the gas phase is relatively complex due to its high nonlinearity. This nonlinearity is induced by several factors including the reaction mechanism, the heat and mass transfer mechanism, the flow properties in both solid and gas phases, the type of reactor, and the correlations between the operating conditions and the chemical and physical properties of the polyolefin. In this study, polymerization of the polypropylene was observed in a fluidized bed reactor to potentially improve the solid elutriation correlations proposed previously, to increase the reliability and the accuracy of this two-phase model. By embedding the improved solid elutriation correlations, the production rate was reduced relative to earlier proposed solid elutriation correlations due to the loss of the product at the top of the fluidized bed reactor. The composition of the reactants and the catalyst flow rate also influenced the production rate, yet the inlet temperature did not.The current two-phase model is validated with the pilot plant data with the deviations lower than the previously validated model with reference to the production rate, the concentration of propylene and hydrogen, and the temperature of the reactor. K E Y W O R D Sfluidized bed reactor, gas phase, polyolefin, propylene, solid elutriation, two-phase model

Section: Kinetic Modelmentioning

confidence: 99%

Dynamic modeling: The influence of the improved solid elutriation correlation on the two‐phase mathematical model of polyolefin polymerization in a gas‐phase fluidized bed reactor

Atan

Asia-Pacific J Chem Eng

2020

“…Either an organometallic‐type catalyst or an initiator such as organic peroxide and oxygen is used. [ 1–6 ] Currently, the most popular gas‐phase polymerization process in the polyolefin industry is olefin polymerization with a fluidized bed reactor. The main advantage of this polymerization process is the economical, flexible, and wide‐ranging availability of catalysts for enhancing the chemical process.…”

Section: Introductionmentioning

confidence: 99%

The influence of catalyst flow rate and superficial gas velocity on the modified two‐phase model for propylene polymerization in a gas‐phase fluidized bed reactor

Atan

Shamiri³

2021

Can J Chem Eng

Olefin polymerization, especially of propylene in gas‐phase fluidized bed reactors, is increasingly prevalent because of its ability to handle the continuous process, among other advantages. The challenge for modelling this process is solving the high nonlinearity phenomena in such a system. This research studies the influence of catalyst flow rate and superficial gas velocity on the modified two‐phase model. The catalyst flow rates were set at 1 × 10−4, 2 × 10−4, and 3 × 10−4 kg/s, while the superficial flow rates were set at 0.35, 0.5, and 0.65 m/s. Production rate, reactor temperature, and heat‐loss flow rate were found to be proportional to catalyst flow rate and inversely proportional to superficial gas velocity. Heat loss through the fluidized bed wall had an influence only on the reactor temperature. Finally, predicted reactor temperatures corresponded closely to the pilot plant data, with deviations smaller than 0.5%.

“…low pressure and temperature) and is less energy‐intensive than the traditional high‐pressure process (2000–3000 atm). High‐purity ethylene and catalyst are continuously fed into a fluidized bed reactor, where ethylene and co‐monomers such as 1‐butene or 1‐hexene are polymerized together at a pressure of 20–30 atm within a narrow temperature range …”

Section: Introductionmentioning

confidence: 99%

Dynamic process modeling and hybrid intelligent control of ethylene copolymerization in gas phase catalytic fluidized bed reactors

Abbasi

Shamiri

J of Chemical Tech & Biotech

et al. 2019

BACKGROUND: Polyethylene (PE) is the most extensively consumed plastic in the world, and gas phase-based processes are widely used for its production owing to their flexibility. The sole type of reactor that can produce PE in the gas phase is the fluidized bed reactor (FBR), and effective modeling and control of FBRs are of great importance for design, scale-up and simulation studies. This paper discusses these issues and suggests a novel advanced control structure for these systems. RESULTS: A unified process modeling and control approach is introduced for ethylene copolymerization in FBRs. The resultsshow that our previously developed two-phase model is well confirmed using real industrial data and is exact enough to further develop different control strategies. It is also shown that, owing to high system nonlinearities, conventional controllers are not suitable for this system, so advanced controllers are needed. Melt flow index (MFI) and reactor temperature are chosen as vital variables, and intelligent controllers were able to sufficiently control them. Performance indicators show that advanced controllers have a superior performance in comparison with conventional controllers. CONCLUSION: Based on control performance indicators, the adaptive neuro-fuzzy inference system (ANFIS) controller for MFI control and the hybrid ANFIS-proportional-integral-differential (PID) controller for temperature control perform better regarding disturbance rejection and setpoint tracking in comparison with conventional controllers.