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

2021 ◽  
Author(s):  
Mohd Farid Atan ◽  
Mohd Azlan Hussain ◽  
Ahmad Shamiri
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Fluidized Bed Reactor ◽  
Phase Model ◽  
Propylene Polymerization ◽  
Gas Velocity ◽  
Two Phase ◽  
Superficial Gas Velocity

scholarly journals Comparative simulation study of gas-phase propylene polymerization in fluidized bed reactors using aspen polymers and two phase models

2013 ◽  
Vol 19 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Ahmad Shamiria ◽  
M.A. Hussaina ◽  
Farouq Mjallic ◽  
Navid Mostoufid
Keyword(s):  
Molecular Weight ◽  
Gas Phase ◽  
Production Rate ◽  
Fluidized Bed ◽  
Average Molecular Weight ◽  
Phase Model ◽  
Propylene Polymerization ◽  
Flow Index ◽  
Fluidized Bed Reactors ◽  
Two Phase

A comparative study describing gas-phase propylene polymerization in fluidized-bed reactors using Ziegler-Natta catalyst is presented. The reactor behavior was explained using a two-phase model (which is based on principles of fluidization) as well as simulation using the Aspen Polymers process simulator. The two-phase reactor model accounts for the emulsion and bubble phases which contain different portions of catalysts with the polymerization occurring in both phases. Both models predict production rate, molecular weight, polydispersity index (PDI) and melt flow index (MFI) of the polymer. We used both models to investigate the effect of important polymerization parameters, namely catalyst feed rate and hydrogen concentration, on the product polypropylene properties, such as production rate, molecular weight, PDI and MFI. Both the two-phase model and Aspen Polymers simulator showed good agreement in terms of production rate. However, the models differed in their predictions for weight-average molecular weight, PDI and MFI. Based on these results, we propose incorporating the missing hydrodynamic effects into Aspen Polymers to provide a more realistic understanding of the phenomena encountered in fluidized bed reactors for polyolefin production.

scholarly journals Fuzzy-GMC Control of Gas-Phase Propylene Copolymerization in Fluidized Bed Reactor

2018 ◽  
Vol 156 ◽  
pp. 07002
Author(s):  
Nazratul Fareha Salahuddin ◽  
Ahmad Shamiri ◽  
Mohd Azlan Hussain ◽  
Navid Mostoufi
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Fuzzy Logic Controller ◽  
Fluidized Bed Reactor ◽  
Solid Particles ◽  
Phase Model ◽  
Regulatory Control ◽  
Generic Model ◽  
Two Phase ◽  
Model Control

A modified two-phase model for gas phase propylene and ethylene copolymerization was chosen to represent the process in a fluidized bed reactor. This model considered the entrainment of solid particles in the reactor, as a modification to the original two-phase model assumptions. The non-linearity of this process makes it difficult to control just by using conventional controller such as PID. A hybrid control strategy (a simple designed fuzzy logic controller (FLC) integrated with generic model control (GMC)) is designed to control the temperature of the reactor. This advanced control system was compared with the GMC and conventional PID controller. The simulation results showed that the hybrid controller (Fuzzy-GMC) performed better than both GMC and PID in terms of both servo and regulatory control.

Performance of a Catalytic Gas–Solid Fluidized Bed Reactor in the Presence of Interparticle Forces

2016 ◽  
Vol 14 (1) ◽  
pp. 433-444 ◽  
Author(s):  
Jaber Shabanian ◽  
Jamal Chaouki
Keyword(s):  
Fluidized Bed ◽  
Flow Model ◽  
Two Phase Flow ◽  
Fluidized Bed Reactor ◽  
Phase Flow ◽  
Gas Velocity ◽  
Hydrodynamic Models ◽  
Two Phase ◽  
Interparticle Forces ◽  
Superficial Gas Velocity

AbstractThe influence of interparticle forces (IPFs) on the hydrodynamics of a gas–solid fluidized bed was experimentally investigated with the help of a polymer coating approach. The results showed that the presence of IPFs in the bed can considerably change the hydrodynamic parameters. The tendency of the fluidizing gas passing through the bed in the emulsion phase increased with IPFs in the bubbling regime. The performance of a fluidized bed reactor was then studied through simulation of a reactive catalytic system using three different hydrodynamic models: (a) a simple two-phase flow model, (b) a dynamic two-phase flow model, and (c) a dynamic two-phase flow model, integrating the effects of superficial gas velocity and IPFs. The simple two-phase flow model was found to underestimate the reactor performance for catalytic reaction most likely due to the oversimplified assumptions involved in this model. Also, the simulation results showed that modification of the bed hydrodynamics due to IPFs resulted in a better performance for a bubbling fluidized bed reactor. This suggests that the hydrodynamic models should take into account the effects of superficial gas velocity and variation in the ratio of the magnitude of IPFs/hydrodynamic forces, due to any operational reason, to yield a more reliable evaluation of the performance of the fluidized bed reactor.

Design and Performance of Slug Damper

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Antonio Reinoso ◽  
Luis E. Gomez ◽  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
...  
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Liquid Velocity ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Gas Velocity ◽  
Flow Loop ◽  
Two Phase ◽  
Superficial Gas Velocity

This study investigates theoretically and experimentally the slug damper as a novel flow conditioning device, which can be used upstream of compact separation systems. In the experimental part, a 3 in. ID slug damper facility has been installed in an existing 2 in. diameter two-phase flow loop. This flow loop includes an upstream slug generator, a gas-liquid cylindrical cyclone (GLCC©, ©The University of Tulsa, 1994) attached to the slug damper downstream and a set of conductance probes for measuring the propagation of the dissipated slug along the damper. Over 200 experimental runs were conducted with artificially generated inlet slugs of 50 ft length (Ls/d=300) that were dumped into the loop upstream of the slug damper, varying the superficial liquid velocity between 0.5 ft/s and 2.5 ft/s and superficial gas velocity between 10 ft/s and 40 ft/s (in the 2 in. inlet pipe) and utilizing segmented orifice opening heights of 1 in., 1.5 in., 2 in., and 3 in. For each experimental run, the measured data included propagation of the liquid slug front in the damper, differential pressure across the segmented orifice, GLCC liquid level, GLCC outlet liquid flow, and static pressure in the GLCC. The data show that the slug damper/GLCC system is capable of dissipating long slugs, narrowing the range of liquid flow rate from the downstream GLCC. Also, the damper capacity to process large slugs is a strong function of the superficial gas velocity (and mixture velocity). The theoretical part includes the development of a mechanistic model for the prediction of the hydrodynamic flow behavior in the slug damper. The model enables the predictions of the outlet liquid flow rate and the available damping time, and in turn the prediction of the slug damper capacity. Comparison between the model predictions and the acquired data reveals an accuracy of ±30% with respect to the available damping time and outlet liquid flow rate. The developed model can be used for design of slug damper units.

Modified two-phase model with hybrid control for gas phase propylene copolymerization in fluidized bed reactors

2015 ◽  
Vol 264 ◽  
pp. 706-719 ◽  
Author(s):  
Ahmad Shamiri ◽  
Suk Wei Wong ◽  
Mohd Fauzi Zanil ◽  
Mohamed Azlan Hussain ◽  
Navid Mostoufi
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Hybrid Control ◽  
Phase Model ◽  
Fluidized Bed Reactors ◽  
Two Phase

scholarly journals Prediction of gas holdup in a combined loop air lift fluidized bed reactor using Newtonian and non-Newtonian liquids

2011 ◽  
Vol 17 (3) ◽  
pp. 375-383
Author(s):  
Sivakumar Venkatachalam ◽  
Akilamudhan Palaniappan ◽  
Senthilkumar Kandasamy ◽  
Kannan Kandasamy
Keyword(s):  
Fluidized Bed ◽  
Particle Diameter ◽  
Fluidized Bed Reactor ◽  
Gas Holdup ◽  
Operating Conditions ◽  
Experimental Results ◽  
Gas Velocity ◽  
Wide Range ◽  
Newtonian Liquids ◽  
Superficial Gas Velocity

Many experiments have been conducted to study the hydrodynamic characteristics of column reactors and loop reactors. In this present work a novel combined loop airlift fluidized bed reactor was developed to study, the effect of superficial gas and liquid velocities, particle diameter, fluid properties on gas holdup by using Newtonian and non-Newtonian liquids. Compressed air was used as gas phase. Water, 5% n-butanol, various concentrations of glycerol (60 % and 80 %) were used as Newtonian liquids, different concentrations of Carboxy Methyl Cellulose (0.25 %, 0.6 % and 1.0 %) aqueous solutions were used as non-Newtonian liquids. Different sizes of Spheres, Bearl saddles and Raschig rings were used as solid phases. From the experimental results it was found that the increase in superficial gas velocity increases the gas holdup, but it decreases with increase in superficial liquid velocity and viscosity of liquids. Based on the experimental results a correlation was developed to predict the gas holdup for Newtonian and non-Newtonian liquids for a wide range of operating conditions at a homogeneous flow regime where the superficial gas velocity is approximately less than 5 cm/s.

Two-phase modeling of a gas phase polyethylene fluidized bed reactor

2006 ◽  
Vol 61 (12) ◽  
pp. 3997-4006 ◽  
Author(s):  
Ali Kiashemshaki ◽  
Navid Mostoufi ◽  
Rahmat Sotudeh-Gharebagh
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Fluidized Bed Reactor ◽  
Two Phase
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