Chemical Engineering Commons^™

New Hybrid Cpu-Gpu Solver For Cfd-Dem Simulation Of Fluidized Bed, Reza Zarghami, N. Mostoufi, H. R. Norouzi

Fluidization XV

Modeling is an alternative to experiment to explore more in multiphase flows. Various modeling approaches have been developed and used from 1D models in the macro-scale to multidimensional models in the micro scale. Well-known modeling approaches for fluidization systems are TFM and CFD-DEM, both have found many practical applications in fluidization systems. The TFM considers both fluid and particulate phase as interpenetrating continua. In contrast, the CFD-DEM considers the fluid as a continuous fluid in the meso-scale (cell-scale) and the solid as discrete particles in the micro-scale. The translational and rotational motions of individual particles are described by applying Newton’s …

Catalytic Ash Free Coal Gasification In A Fluidized Bed Thermogravimetric Analyzer, Said Samih, Jamal Chaouki

Fluidization XV

Catalytic ash free coal gasification was investigated in the newly developed fluidized bed thermogravimetric analyzer. The total yield obtained from the fluidized bed TGA showed good agreement with the total gas product. For char gasification, the values of activation energy and pre-exponential factor were similar to those obtained from coal gasification in our previous work. The activation energy for the CO shift reaction decreased by 56% and 37% from the value reported in our previous work for coal gasification and in literature for catalytic coal gasification respectively. For the methane reforming reaction, the value of the activation energy was reduced …

Fundamentals Of Rotating Fluidized Beds And Application To Particle Separation, Justin M. Weber, Richard C. Stehle, Ronald W. Breault, Larry Shadle

Fluidization XV

Rotating fluidized beds provide unique opportunities to exploit fluidization under higher particle forces. The centripetal force in a rotating bed is typically on the order of 10 times the force of gravity. Since the force keeping the particles in the unit is larger, the drag force can also be larger, allowing for higher gas velocities. This operating regime provides opportunities for higher mass transfer, heat transfer, gas throughput, and bubble suppression.

One application for using a rotating fluidized bed in in Chemical Looping Combustion (CLC). When solid fuels are used, oxygen carrier and ash are mixed in the process. In …

Mixing And Segregation In Fluidized Bed Thermochemical Conversion Of Biomass, Piero Salatino

Fluidization XV

The recent shift in policy intentions catalysed by COP21 is stimulating the much-needed global energy transition giving new momentum to the move towards a lower-carbon and more efficient energy system. Bio-based energy and chemicals are taking the lead in the progress toward extensive replacement of fossil resources with renewables.

Fluidized bed thermochemical conversion of biomass (combustion, gasification, pyrolysis) displays a long record of successes, spanning from lab- to industrial scales, and stems out as the most viable pathway for the exploitation of biogenic fuels, either alone or in combination with fossil fuels. In spite of its diffusion, there are still …

Cfd-Dem Modeling Of Fluidized Beds With Heat Production: Influence Of The Particle Size Distribution And Heat Source, Zizi Li, Martin Van Sint Annaland, Niels G. Deen, J.A.M. Kuipers

Fluidization XV

Gas-phase polyolefin polymerization processes are executed in fluidized beds. The particles often have a broad particle size distribution (PSD) due to a variety of factors (e.g. residence time distribution, initial catalyst size distribution, different rate of catalyst activity decay, etc.). The heat transfer phenomena of particles in poly-disperse beds with different particle size distributions have been numerically analyzed using an in-house developed 3-D computational fluid dynamics and discrete element model (CFD-DEM) (1). Simulations have been carried out for beds with Gaussian PSD’s using three different distribution widths, viz. a narrow, medium and broad distribution (see figure 1), but with the …

Fluid-Dynamic Study On A Multi-Stage Fluidized Bed Column For Continuous Co2 Capture Via Temperature Swing Adsorption, Schöny. G, Zehetner. E, Fuchs. J, Hofbauer. H, Pröll. T

Fluidization XV

Adsorption based processes have a great potential to significantly reduce the overall costs of CO2 separation from stack flue gas as compared to currently available technologies. One of the main challenges in the development of these processes is certainly the provision of adequate adsorbents. Hence, in the last decade a great effort has been put into screening and testing of various adsorbent materials.

However, beside the identification of suitable adsorbent materials it is of equal importance to develop suitable reactor designs that allow for effective and most cost efficient utilization of these materials and so far only little work has …

Dynamic Flowsheet Simulation Of Gas And Solids Flows In A System Of Coupled Fluidized Bed Reactors For Chemical Looping Combustion, Johannes Haus, Ernst-Ulrich Hartge, Stefan Heinrich, Joachim Werther

Fluidization XV

A novel flowsheet simulation environment is applied to the Chemical Looping Combustion of solid fuels in order to capture dynamic behavior of fluid dynamics inside the system. The process itself is carried out in the majority of cases in a pair of strongly coupled fluidized bed reactors. The plant operated at the TUHH, which is simulated there, comprises a circulating fluidized bed air reactor and a two-stage bubbling bed fuel reactor demonstrated in the Figure.

The modelled riser of the circulating fluidized bed system consists of a dense bottom phase and a dilute upper part. The fuel reactors are implemented …

Monitoring Of The Hydrodynamic Instabilities In Conical Spouted Beds By Recurrence Plot Analysis Of Pressure Fluctuations And Acoustic Emission Signals, Rahmat Sotudeh-Gharebagh, Chiya Savari, Navid Mostoufi, Reza Zarghami, Gorkem Kulah, Murat Koksal

Fluidization XV

Spouted beds are extensively used in coating and granulation processes with the presence of liquid in the bed (1). The liquid may increase particle cohesiveness and result in de-spouting, leading to the bed malfunctioning. Hydrodynamic of the bed may alter over time due to instabilities imposed by particle size changes and cohesiveness. Therefore, conditional monitoring of spouted beds is crucial since the performance of these beds strongly depends on its hydrodynamics. A method capable of detecting bed instabilities may not be only useful for preventing undesirable situations (e.g., agglomeration and de-spouting), but also may be utilized to control the product …

Numerical Simulation Of Hydrogen Production By Chemical Looping Reforming In A Dual Interconnected Fluidized Bed Reactor, Piero Bareschino, Roberto Solimene, Giuseppe Diglio, Erasmo Mancusi, Francesco Pepe, Piero Salatino

Fluidization XV

Although exploitation of dual interconnected fluidized bed systems (DIFB) is currently being explored in various fields (1,2), DIFBs present some criticalities, mainly related to effective control of solids recirculation and to avoidance of gas leakage between the beds, extremely critical in chemical looping reforming (CLR) for hydrogen production. For the latter, the choice of the degree of oxygen carrier oxidation/reduction, operation temperature and loop design makes the design even more challenging. This paper aims at quantitative assessment of the influence of design variables by means of the numerical simulation of a DIFB-CLR process operated at steady state. The model couples …

Influence Of Bubble Bursting On Heat Transfer Phenomena In Directly Irradiated Fluidized Beds, Roberto Solimene, Claudio Tregamb, Piero Salatino, Riccardo Chirone, Fabio Montagnaro

Fluidization XV

Concentrating Solar Power (CSP) is a fast-growing technology in which several hundreds/thousands of optical mirrors concentrate the solar energy onto a receiver. The received energy can be used to produce electricity through thermodynamic cycles or to drive an endothermic chemical reaction for chemicals production (e.g. solar fuels) or for chemical storage. The receiver is a crucial part of the whole system, as it owns the severe task of collecting and transferring the concentrated solar energy minimizing the heat losses. Dense fluidized beds have been proposed as CSP receivers thanks to their large heat-transfer and thermal diffusivity coefficients, and their use …

Measurement Of Penetration And Cycle Time Of Jets From An Industrial Fluid Coking Spray Nozzle, Francisco Sanchez Careaga, Cedric Briens, Franco Berruti

Fluidization XV

Fluid Coking^TM is a process to upgrade heavy oils through thermal cracking. Oil is injected in a downward-flowing bed of hot coke particles, where it heats up and cracks into smaller vapour molecules. The down-flowing coke particles are sent to a burner where they are reheated and send back to the reactor to provide heat for cracking reactions. Liquid sprayed with atomization gas into a fluidized bed forms a jet cavity that absorbs bubbles from the bubbling bed and periodically releases a large bubble from its tip. The jet penetration length, thus, cycles. With a faster jet cycle, the …

Using Of Spouted Bed Spray Granulation Process For Fabricating Of Metal/Ceramic-Polymer Composites, Eduard Eichner, V. Salikov, M. Dosta, S. Heinrich, G.A. Schneider

Fluidization XV

Naturally occurring structural materials are composites with very high filling degrees on hard constituent. In recent years structure and properties of biological materials have been studied in detail. But it has not been possible to reconstruct this structural design. In this contribution we present a process for the fabrication of very highly filled composite materials by using of the spouted bed spray granulation process.

Spouted bed granulation offers many advantages for the design of composite materials. In this investigation fine particles (dP =10-50 µm) could be uniformly spouted, and optimal properties for further processing to bulk materials can …

Catalyst Preparation For Fluidized Bed Reactors By Spray Drying, Nooshin Saadatkhah, Gregory S. Patience, Daria C. Boffito, Marco G. Rigamonti, Seyedfoad Aghamiri, Mohammad Reza Talaie

Fluidization XV

Spray dried fluidized bed catalysts belong to the Geldart Group A classification and vary between 22 m to 200 m in diameter (1). Binder is either distributed throughout the particle with the active phase or surrounds the active phase as in a core-shell structure (2, 3). We slurried WO₃/TiO₂ micronized powder (0.2 m to 2 m) with colloidal silica (LUDOX^® HS-40) to form a slurry with a mass fraction of 5 % to 20 % solids. The solution entered the top of GB-22 Yamato fluidized bed spray dryer chamber (0.12 m ID) through a two-fluid nozzle …

Experimental And Simulation Study On Heat Transfer In Fluidized Beds With Heat Production: An Integrated Dia/Piv/Ir Technique And Cfd-Dem, Zizi Li, Tom C.E. Janssen, Martin Van Sint Annaland, J.A.M. Kuipers, Niels G. Deen

Fluidization XV

As a result of highly exothermic reactions taking place in gas-phase olefin polymerization fluidized bed reactors, difficulties concerning the heat management play an important role in the optimization of these reactors. To get a better understanding of the particle temperature distribution in fluidized beds, a high speed infrared (IR) camera and a visual camera have been coupled to obtain the hydrodynamics and thermal aspects of a pseudo-2D fluidized bed (1), as shown in figure 1. The hydrodynamics are characterized by digital image analysis and particle image velocimetry (DIA/PIV) and the heat properties by IR. The experimental data is used to …

A Multi-Stage Fluidized Bed System For Continuous Co2 Capture By Means Of Temperature Swing Adsorption – First Results From Bench Scale Experiments, Schöny G, Florian Dietrich, Fuchs. J, Hofbauer. H, Pröll. T

Fluidization XV

Temperature swing adsorption processes have been proposed as an alternative to common amine scrubbing processes for CO2 capture from stack flue-gas streams, as they have the potential to reduce the overall capture costs significantly. In the recent years, researchers have put a great effort into the development of highly selective CO2 adsorbent materials with sufficiently large CO2 transport capacities and cyclic operating stability. However, comparably little work has been attributed to the development of suitable reactor designs or to the experimental study of continuously operated temperature swing adsorption (TSA) processes that utilizes those adsorbent materials.

The authors of this work …

Dense Gas-Particle Suspension Upward Flow Used As Heat Transfer Fluid In Solar Receiver: Pept Experiments And 3d Numerical Simulations, Renaud Ansart, Pablo Garcia-Triñanes, Benjamin Boissière, Hadrien Benoit, Jonathan Seville, Olivier Simonin

Fluidization XV

Dense particle suspension, also called an Upflow Bubbling Fluidized Bed (UBFB), is an innovative alternative to the heat transfer fluids classically used in concentrated solar power (CSP) plants. Indeed, such fluids have several limitations: restricted range of operating temperatures, significant safety issues, corrosion problems and high maintenance costs. The CSP2 (Concentrated Solar Power in Particles) FP7 European project (http://www.csp2-project.eu/) has the ultimate goal of developing commercially-viable CSP plants based on granular media as the heat transfer fluid, where power is transmitted to the particles by the receiver walls (metal or ceramic), which are themselves subject to solar radiation. An additional …

Validation Of The Oxygen Buffering Ability Of Bed Materials Used For Ocac In A Large Scale Cfb Boiler, Angelica Corcoran, Fredrik Lind, Henrik Thunman

Fluidization XV

Fluidized bed combustion is widely considered an advantageous technology managing moist and heterogeneous fuels due to the heat storage in the bed material and its favorable conditions regarding fuel and oxygen mixing throughout the combustion chamber. Even though mixing is often regarded as sufficient, the technology remains sensitive to variations in load and heterogeneity of fuels, leading to an uneven distribution of oxygen in time and space of the furnace. The remedy has nearby exclusively been related to the supply of air, particularly considering a surplus of air and positioning of injection ports.

An applicable combustion concept, oxygen carrier aided …

A 1.5d Model Of A Complex Geometry Laboratory Scale Fuidized Bed Clc Equipment, Jaroslaw Krzywanski, A. Żylka, T. Czakiert, K. Kulicki, S. Jankowska, W. Nowak

Fluidization XV

The awareness of the climate changes has resulted in the development of new technologies allowing to increase the effectiveness and to lower the costs of CO2 separation from the flue gas. One of the most promised combustion technology of fossil fuels is Chemical Looping Combustion (CLC). The technology is considered to be one of the cheapest techniques for CO2 capture (1). Since it is still an emerging technology and the complexity of processes are still not sufficiently recognized, the development of a simple model of CLC equipment is of practical significance.

The paper presents a 1.5D model of the laboratory-scale …

Effect Of Interactions Between Spray Jets On Liquid Distribution In A Fluidized Bed, Helal Elkolaly, Cedric Briens, Franco Berruti

Fluidization XV

In Fluid CokersTM, banks of spray nozzles are used to inject oil in a bed of hot coke particles. The purpose of this study is to determine whether interactions between spray jets could enhance liquid distribution on hot coke particles, which is crucial to improve the operability and performance of Fluid Cokers.

A low temperature experimental model of Fluid Coking was used to measure the liquid distribution. Preliminary screening of nozzle positions employed conductance measurements. A binder solution was utilized to further investigate the most interesting nozzle interactions, by simulating at low temperature the formation of agglomerates during high temperature …

Experimental Characterization Of Operational Regimes In Low Aspect-Ratio Cfb Risers, Tove Karlsson, Xuemin Liu, Filip Johnsson, David Pallarès

Fluidization XV

This work discusses operational regimes in CFB-furnaces by means of mapping the relation between fluidization velocity, riser pressure drop and external solids circulation. A cold CFB unit with riser dimensions 0.8 × 0.12 × 8.5 m is used, thus yielding a riser height-to-width aspect ratio of 10.6, similar to that of typical CFB boilers (1). The overall flow regime established in the unit has been shown to be representative for large-scale CFB boilers, while providing the opportunity to investigate a wide range of operational parameters, including such that are not easily applicable to real boilers. The operational conditions covered fluidization …