DEM simulation of fluidized beds for gas-phase olefin polymerization

1999 ◽  
Vol 54 (24) ◽  
pp. 5809-5821 ◽  
Author(s):  
Yasunobu Kaneko ◽  
Takeo Shiojima ◽  
Masayuki Horio
Keyword(s):  
Gas Phase ◽  
Fluidized Beds ◽  
Olefin Polymerization ◽  
Dem Simulation

A Laboratory Reactor for Gas-Phase Olefin Polymerization

2008 ◽  
Vol 82 (2) ◽  
pp. 371-381 ◽  
Author(s):  
Tariq M. Mannan ◽  
Hassan Hammawa ◽  
David T. Lynch ◽  
Sieghard E. Wanke
Keyword(s):  
Gas Phase ◽  
Olefin Polymerization ◽  
Laboratory Reactor

Combustion of Biomass in Fluidized Beds: Problems and Some Solutions Based on Danish Experiences

2003 ◽  
Author(s):  
Weigang Lin ◽  
Anker D. Jensen ◽  
Jan E. Johnsson ◽  
Kim Dam-Johansen
Keyword(s):  
Gas Phase ◽  
Fluidized Beds ◽  
Early Stage ◽  
Full Scale ◽  
Boiler Load ◽  
High K ◽  
Fundamental Understanding ◽  
Annual Biomass ◽  
Operation Parameters ◽  
Boiler Design

This paper summarizes the major problems in firing and co-firing the annual biomass, such as straw, in both lab-scale and full-scale fluidized bed combustors. Two types of problems were studied: operational problems, such as agglomeration, deposition and corrosion; and emission problems, e.g. emissions of NO and SO2. Measurements of deposition and corrosion rate on the heat transfer surfaces, as well as gas phase alkali metal concentrations, were performed in full scale CFB boilers (an 80 MWth and a 20 MWth plant), which have been co-firing coal with straw and other biomass. Severe corrosion and deposition were observed in the superheater located in the loop-seal of the 80 MWth boiler. The boiler load variation has impact on the operation parameters. When the fraction of biomass with a high K-content (>1 wt. %) was higher than 60% on a thermal basis, the boiler suffered from severe agglomeration problems. Lab-scale experiments were carried out for the fundamental understanding of phenomena found in full-scale boilers and for testing possible solutions to the problems. The results showed a strong tendency of agglomeration in fluidized beds during combustion of straw, which normally have a high content of potassium and chlorine. The results indicate that the operational problems may be minimized by a combination of additives, improved boiler design, split of combustion air and detection of agglomeration at an early stage.

scholarly journals Hybrid Two-Fluid DEM Simulation of Gas-Solid Fluidized Beds

2006 ◽  
Author(s):  
Jin Sun ◽  
Francine Battaglia ◽  
S. Subramaniam
Keyword(s):  
Momentum Transfer ◽  
Fluidized Beds ◽  
Structural Information ◽  
Fluid Model ◽  
Fluid Phase ◽  
Transfer Model ◽  
Dem Simulation ◽  
Dem Simulations ◽  
Two Fluid Model ◽  
Two Fluid

Simulations of gas-solid fluidized beds have been carried out using a hybrid simulation method, which couples the discrete element method (DEM) for particle dynamics with the ensemble-averaged two-fluid (TF) equations for the fluid phase. The coupling between the two phases is modeled using an interphase momentum transfer term. The results of the hybrid TF-DEM simulations are compared to experimental data and two-fluid model simulations. It is found that the TF-DEM simulation is capable of predicting general fluidized bed dynamics, i.e., pressure drop across the bed and bed expansion, which are in agreement with experimental measurements and two-fluid model predictions. In addition, the TF-DEM model demonstrates the capability to capture more heterogeneous structural information of the fluidized beds than the two-fluid model alone. The microstructures in fluidized beds are analyzed and the implications to kinetic theory for granular flows are discussed. However, the TF-DEM simulations depend on the form of the interphase momentum transfer model, which can be computed in terms of averaged or instantaneous particle quantities. Various forms of the interphase momentum transfer model are examined, and their suitability to the hybrid TF-DEM simulation approach is evaluated.

Evaluation of the Internal Particle Morphology in Catalytic Gas-Phase Olefin Polymerization Reactors

2007 ◽  
Vol 46 (7) ◽  
pp. 1928-1937 ◽  
Author(s):  
V. Kanellopoulos ◽  
E. Tsiliopoulou ◽  
G. Dompazis ◽  
V. Touloupides ◽  
C. Kiparissides
Keyword(s):  
Gas Phase ◽  
Olefin Polymerization ◽  
Particle Morphology ◽  
Internal Particle
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