Engineering Commons^™

2-D Simulation Of The Catalytic Dechlorination Of P-Chlorophenol In A Magnetically Stabilized Fluidized Bed, Joaquín Pinto-Espinoza, Damian Reyes-Jaquez, Adriana Martínez-Prado, Carlos F. Cruz-Fierro

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This study adopted the fundamentals of the catalytic dechlorination of p-chlorophenol in a MSFB column, technology developed by Graham (1). A CFD-DPM approach is used to simulate the catalytic process. The code is validated by comparison with the experimental results, considering the p-chlorophenol removal and the particle catalyst deactivation.

Photocatalytic Degradation Of Toluene By Nano-Tio2 In A Fluidized Bed, Xiaoping Zhang, Cong Liao

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The mixed gas of toluene and air was used as treated gas, self-made fluidized bed and ultraviolet lamp and TiO2/silica gel prepared in laboratory used as photo reactor and light source and photo-catalyst respectively to degrade toluene in the treated gas. The effects of operating parameters including initial concentration, operating gas velocity, ultraviolet light intensity and bed layer height on degradation rate of toluene have been probed into in this research. The results showed that degradation rate of toluene was independent of initial concentration (20～55mg/m3) but decreased with higher initial concentration; the degradation rate of toluene increased with gas velocity …

Fluidized Bed Polymer Particle Ald Process For Producing Hdpe/Alumina Nanocomposites, Joseph A. Spencer, Xinhua Liang, Steven M. George, Karen J. Buechler, John Blackson, Charles J. Wood, John R. Dorgan, Alan W. Weimer

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Micron-sized High Density Polyethylene (HDPE) particles were coated with ultrathin alumina (Al2O3) films in a Fluidized Bed Reactor (FBR) by Atomic Layer Deposition (ALD) at 77 ºC. Al2O3 films on the HDPE particles were confirmed by different methods. These particles were extruded conventionally with the ceramic shells mixing intimately in the polymer matrix. The successful dispersion of the Al2O3 shells in the polymer matrix following extrusion was confirmed using cross sectional Transmission Electron Microscopy (TEM).

Influence Of Fb Conditions On Processes Within A Large Fuel Particle During Initial Phases Of Conversion, Milijana Paprika, Mirko Komatina, Franz Winter, Dragoljub Dakic

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A theoretical study has been performed in order to investigate the interaction between fluidized bed (FB) temperature and original size of coal, and the pressure rise within a large coal particle during the initial phases of the combustion process. A mathematical model, describing the devolatilization process, has included the internal and external heat transfer, primary decomposition reactions and mass transfer. The model has shown how the FB temperature and original size of coal reflect on the pressure profile of the coal particle during the devolatilization. One of the major consequences of coal devolatilization in the fluidized bed is the primary …

Performance Characteristics Of An 8 Mw(Th) Combined Heat And Power Plant Based On Dual Fluidized Bed Steam Gasification Of Solid Biomass, Tobias Pröll, Reinhard Rauch, Christian Aichernig, Hermann Hofbauer

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The work focuses on a dual fluidized bed gasification technology for which a model has been developed and validated accompanying the operation of the 8 MWth biomass combined heat and power plant in Guessing/Austria. The reactor concept is a circulating fluidized bed system with a large steam-fluidized bubbling bed integrated into the solids return loop. The solids circulation rate is shown versus the riser exit velocity. Further, plant performance maps are presented for both electric and heat power output. The water content of the fuel is a major parameter with respect to plant performance. High fuel water content at high …

Modeling Fuel Mixing In A Fluidized Bed Combustor, David Pallarès, Filip Johnsson

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper presents a 3-dimensional model for fuel mixing in fluidized bed combustors. The model accounts for the mixing patterns experimentally shown to govern the mixing in the different zones of the riser and the return leg and can be applied both under bubbling and circulating regimes. Thus, the semi-empirical basis of the model was previously validated in different large-scale fluidized bed combustors and is combined with a model for fuel particle conversion to obtain the fuel concentration. Results obtained with the model are compared with experimental data from the Chalmers 12 MWth CFB combustor, yielding reasonably agreement.

Fast Pyrolysis Of Biomass In A Circulating Fluidised Bed, Manon Van De Velden, Xianfeng Fan, Andy Ingram, Jan Baeyens

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

CFB biomass pyrolysis produces mostly bio-oil. Reaction rates are fast (k > 0.5 s-1). Yields exceed 60 wt% of bio-oil at 500 °C and at a residence time for oil and char t < 2.5 s. as achieved in plug flow CFB-mode, shown by PEPT to occur at U > (Utr + 1) m/s and G > 200 kg/m² s.

Modeling Of An Interconnected Fluidized Bed Reactor For Chemical Looping Combustion, Min Xu, Naoko Ellis, Ho-Jung Ryu , C. Jim Lim

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Chemical Looping Combustion (CLC) is comprised of two reactors, in which direct contact between air and fuel is avoided. A metal oxide, as oxygen carrier, transports oxygen from the air reactor to the fuel reactor while circulating between them. Based on the hydrodynamics coupled with reaction kinetics of oxygen carrier from the literature, a model for an interconnected fluidized bed reactor has been developed to optimize the design and operation of the reactor system. The model considers the chemical reaction of a single particle and a particle population balance for the calculation of bed particle conversion. The core-annulus and two-phase …

Experimental Analysis Of Fuel Mixing Patterns In A Fluidized Bed, David Pallarès, Pedro A. Díez, Filip Johnsson

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The mixing pattern of a tracer particle which simulates a fuel particle is studied in a cold 2-dimensional fluidized bed with respect to the influence of fluidization velocity, bed height, tracer particle size and air-distributor pressure drop under conditions typical for bubbling fluidized bed boilers as well as the bottom region of circulating fluidized bed boilers. The results show that for all conditions studied, the tracer particle follows a flow pattern structured into horizontally-aligned vortexes.

Continuous And Semi-Continuous Operations Of Chemical-Looping Combustion In An Annular Fluidized Bed Reactor With Solids Circulation, Sung Real Son, Sang Done Kim, Jea-Keun Lee

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Chemical-looping combustion (CLC) of methane was carried out in an annular shape fluidized bed reactor with double circulations. Combustion efficiency of the continuous and semi-continuous operations with NiO and Fe2O3 supported on bentonite were determined. Combustion efficiencies of the semi-continuous operations with NiO/bentonite and Fe2O3/bentonite are over 99 % in both cases, and those of the continuous operations are around 97 % and 72 %, respectively. The chemical reactivity of NiO is higher than Fe2O3 in the CLC process. The concentration of CO in flue gas was below 1% and no H2 emission was detected.

Experimental And Computational Studies Of Gas Mixing In Conical Spouted Beds, Zhiguo Wang, C. Jim Lim, Xiaotao T. Bi

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The residence time distribution data in a conical spouted bed, obtained both from the bed bottom and the bed surface at different radial positions, were analyzed to obtain the mean residence time and the Peclet number. In parallel, local flow structures of a bed with the same dimensions and operating conditions as in the experiment were generated from the computational fluid dynamics (CFD) simulation using the FLUENT codes, and then were used for the simulation of gas dispersion. The results show that CFD simulations agree reasonably well with experiments. The radial distribution of the Peclet number is quite complex, with …

The Influence Of Air Nozzles' Shape On The Nox Emission In The Large-Scale 670 Mwt Cfb Boiler, Pawel Mirek, Robert Sekret, Wojciech Nowak

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

An analysis of the influence of air nozzles’ shape design on the NOx emission in the large-scale CFB boilers operated under comparable operating conditions was undertaken in the study. The obtained results have shown, that the change in primary air distribution in the lower part of the combustion chamber has substantially influenced the intensity of the combustion process and the temperature distribution along the CFB structure height.

Particle Population Balances In A Refuse Derived Fuel Fired Circulating Fluidized Bed Combustor, Kai Redemann, Ernst-Ulrich Hartge, Joachim Werther

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

With a population balance model the effects of changes in the operation of a circulating fluidized bed combustor on the bed inventory are simulated. Feeding, discharge and recirculation of solids as well as separation effects in the combustion chamber and in the cyclone are considered. The model predictions are compared with measurements at the refuse-derived fuel incineration plant Neumuenster. The simulation shows that by sieving of the ash withdrawn from the bottom of the combustion chamber and recycling the fine fractions to the bed the non-elutriable fraction of the ash in the bottom zone of the circulating fluidized bed (CF …

Scaling Relationships Of Gas-Solid Spouted Beds , Jian Xu, Ye Ji, Weisheng Wei, Xiaojun Bao, Wei Du

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

An additional parameter, the particle-particle coefficient of restitution was added to the scaling relationship of spouted beds proposed by He et al. (4) by granular kinetic theory analysis of the particle movements in both spout and annulus regions. The experimental verification was conducted in two spouted beds with 80 and 120 mm ID. It has been found that good similarity could not be obtained when the coefficients of restitution were not matched.

Cold Modelling Of An Internally Circulating Fluidized Bed Membrane Reactor, Tony Boyd, John R. Grace, C. Jim Lim, A. M. Adris

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A novel fluidized bed membrane reactor with internal catalyst circulation is being developed for the production of high-purity H2 from an autothermal reformer. In order to provide guidance to pilot reactor testing, a cold model was built to study the influence of reactor configuration on hydrodynamics and catalyst circulation. It was found that catalyst circulation was reproducible, but that parallel non-communicating flow channels could lead to flow instability. Solids circulation was found to be adequate for design of the autothermal reformer.

Thermal Conversion Of Biomass And Waste, Liban Yassin, Paola Lettieri, Stefaan Simons, Antonino Germanà

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper investigates the process designs of 2 fluidized bed gasification plants utilizing clean biomass. Energy and mass balances for each process were carried out and ChemCAD was used to evaluate the energy recovery process by simulating the operation of a steam turbine and a combined cycle gas turbine (CCGT).

Numerical Simulation Of Spouted Bed Reactors Using Process Engineering Models: Application To Coal Gasification, Alexandra Mendes, Alain Dollet, Carine Ablitzer, Gilles Flamant, Christophe Perrais

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A spouted bed reactor operating at high temperature has been modelled using one dimensional models based on process engineering concepts. The process of coal gasification has been selected to demonstrate the models achievements and predictions have been compared to previous spouted bed reactor experimental results.

Bubble Size And Mass Transfer In A Modified Airlift Loop Reactor With Continuous Slurry Phase, Mengxi Liu, Chunxi Lu, Mingxian Shi

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A modified internal airlift loop reactor with continuous slurry phases was explored to investigate the local bubble size and the local mass transfer properties. A mathematical model was derived to simulate the bubble size in every flow region. Also, a new method was developed to measure the dissolved oxygen concentration.

Fluid Mechanical Phenomena Of Liquid-Solid Fluidization In The Centrifugal Field, Jan Margraf , Joachim Werther

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The flow pattern in a rotating liquid-solid fluidized bed with particles in the micron range was investigated in the bed and in the freeboard. Simulations of the liquid flow in absence of particles with the CFD-Software CFX 5.7 showed a strong influence of the Coriolis force, which results in high tangential velocities. Experiments in a 1 m diameter rotor confirmed the results of the simulation. The fluidized bed is also moving in the tangential direction. The bed expansion is described by a Richardson-Zaki type correlation.

Numerical Modelling Of Sloshing With Vof Method, Hamid Rezaei, Mohammad Javad Ketabdari

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Sloshing in tanks carrying LNG, LPG and petroleum is an important phenomenon as dynamic pressure arises from sloshing can destroy the containing tanks. So it is vital to consider this phenomenon in design stages of carriers. The governing equations in fluid flow are conservation of mass and momentum. Modeling of free surface flow in tank needs a suitable tool. One of the most powerful tools to model the free surface is VOF method. Employing additional transport equation together with conservation of mass and momentum enable us to follow the free surface changes. A computer code was developed to evaluate sloshing …

Dynamic Simulation Of Gas Hydrate Formation In An Agitated Three-Phase Slurry Reactor, Shahrzad Hashemi, Arturo Macchi , Phillip Servio

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Gas hydrate growth was simulated in an agitated three-phase slurry reactor using a dynamic model that incorporates hydrate formation kinetics as well as system hydrodynamics and interphase heat and mass transfer rates. Supersaturation ratios and mole consumption rates were evaluated as a function of time for different gas and liquid superficial velocities. Based on available data and the conditions investigated, the kinetic resistance was found to be more influential than the resistance to gas-liquid mass transfer.

Hydrodynamic And Rtd Of Sectionalized Bubble Column, Nahidh W. Mecaial, Burhan Sadik

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The sectionalization of conventional bubble columns to tray partitioned bubble column using perforated trays has been used to investigate the effect of tray hole diameter, tray open area, superficial gas velocity, gas sparger design, and liquid phase properties on gas holdup, residence time distribution (RTD), and overall liquid-phase backmixing. The erected column is sectionalized into three stages using two perforated plates of different holes diameter and open free area. Overall gas holdup is measured experimentally by bed expansion technique. Liquid backmixing, mixing time and axial dispersion model (ADM) is determined using tracer response experiments. In general, it seems that the …

Role Of Intrinsic Kinetics And Catalyst Particle Size Distribution In Cfd Simulations Of Polymerization Reactors, Rong Fan, Rodney O. Fox, Michael E. Muhle

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Fluidized-bed reactors are widely used in the production of polyethylene. In this work, the quadrature method of moments (QMOM), a chemical reaction engineering (CRE) model, and computational fluid dynamics (CFD) are combined to investigate the role of intrinsic kinetics and the catalyst particle size distribution (PSD) in a gas phase fluidized bed reactor. The catalyst PSD is represented by a few nodes using the QMOM and an intrinsic rate model based on the age of particles is used to solve the evolution of particle temperature, particle size, and catalyst sites with age. Assuming the particle age distribution is well-mixed, the …

Particle Size Distribution In Gas-Phase Polyethylene Reactors, Omid Ashrafi, Navid Mostoufi, Rahmat Sotudeh-Gharebagh

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A population balance model is developed to investigate the particle-size distribution developments in a gas-phase fluidized-bed ethylene polymerization reactor. The model considers the combined effects of particle growth and elutriation for size distributed prepolymer feed. In the proposed model, the bed is divided into several sections consisting of bubble and emulsion phases. The population balance differential equations derived for each section were simultaneously solved to determine the density function of the size distribution of the polymer particles in each section. The model is able to predict the axial profiles of particle size distribution. It was also shown that the mean …

Volume Contraction In Liquid Fluidization Of Binary Solids Mixtures, Norman Epstein , R. Escudié, John R. Grace, Xiaotao T. Bi

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

When liquid-fluidized particles of radically different sizes and densities mix, the serial (additive volume) model fails to predict the fluidized bed voidage due to contraction of the mixed bed relative to the volumetric sum of the corresponding monocomponent beds. Models are proposed to predict contraction reported in the literature for both upflow and downflow fluidization.

Hydrodynamics Of Gas-Solids Bubbling Fluidized Beds Using Polyethylene Resin, Bangyou Wu, John Shepperson, Loni Van Der Lee, Céline Bellehumeur, Apostolos Kantzas

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Pressure fluctuations were measured in three gas-solids bubbling fluidized beds (10cm, 20cm, and 30cm diameter, 1.0m high) using polyethylene particles of different sizes and particle size distributions. Both bed scale and particle size distribution significantly affect the gas-solids flow behavior. Bubble diameters measured from X-ray fluoroscopy in the 10cm diameter column were compared to various correlations in the literature.

Monitoring Electrostatic Charges In Fluidized Beds, Xiaotao T. Bi, Aihua Chen, John R. Grace

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A novel analysis procedure for dynamic collision probes has been developed to monitor the charge density of particles in gas-solids fluidized beds based on the mean and normalized standard deviation of current signals. The contribution from hydrodynamic changes is decoupled from the changes in specific particle charge density based on the principles that the average current is related to charge transfer and/or triboelectrification due to the contact between the probe and particles, whereas the normalized standard deviation of current signals is mainly related to the hydrodynamic changes of the fluidized bed. The correlation between hydrodynamic changes and current signal fluctuations …

The Measurement Of Thermal Performance For A Fluidized Bed, H. R. Goshayshi

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Abstract Experiments have been performed to measure the thermal performance, packed density, and velocity of a fluidized bed cooling tower of 280 mm diameter.

Hollow plastic spheres of three different sizes, with diameters of 20, 25 and 37 mm and particle densities ranging from 70 to 325 kg/m3 were investigated as packing materials, and results for static bed heights of 100 mm and 300 mm are reported. Measurements were obtained at an approximately constant inlet hot water temperature of around 42°C and cover a range of water mass flux from 0.3 to 3.6 kg/sm2. Liquid/gas ratios varied between 0.1 and …

Towards Selective Agglomeration Detection In Fluidized Beds Using Advanced Signal Analysis Methods, Malte Bartels, Bart Vermeer, John Nijenhuis, Ruud Van Ommen, Freek Kapteijn

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A new methodology of assessing large amounts of fluidized bed pressure fluctuation data with various signal analysis methods in combination with signal pre-treatment methods is presented. This approach can be used to find certain combinations that are selectively sensitive to certain physical effects in fluidized beds, such as agglomeration.

Investigation Of The Sources Of Variability In The Wurster Coater: Analysis Of Particle Cycle Times Using Pept , Sarah Palmer, Andy Ingram, Xianfeng Fan, Shaun Fitzpatrick, Jonathan Seville

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Positron Emission Particle Tracking (PEPT) has been used successfully to study pellet motion within the Wurster coater. PEPT experiments were undertaken to understand how the parameters of batch size and partition gap interact with each other; and to determine their effects on the particle cycle time and the components of the particle cycle time: the flight and annulus times and their respective distributions. This enabled the determination of optimum operating conditions for a given set of process conditions.