Engineering Commons^™

Effect Of Horizontal Passage Length On Solid Recycle Through A Loop Seal In A Circulating Fluidized Bed, James W. Butler, Prabir Basu

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

Solid flow through the loop seal of a circulating fluidized bed (CFB) was studied by investigating the effect of the horizontal passage length on solid flow through the loop seal. This was done by investigating the effects of aeration on the inter-particle friction forces, the effect varying horizontal passage lengths had on the overall solid flux around the CFB loop and on the pressure drop across the passage. The division of air flow through the loop seal was also investigated in order to determine how the solids were driven through the loop seal. It was found that for a measurable …

Drying Of Moist Solid Particulate In A Bubbling Fluidised Bed, Yassir Makkawi, Jamie Duncan, Marc Mcandrew, Raffaella Ocone

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

Air at ambient conditions was used to dry moist particles at various fluidisation velocities. Throughout the drying process, images of the material distribution were recorded using Electrical Capacitance Tomography (ECT). Simultaneously, the outlet air moisture content was measured using temperature/humidity probe. The ECT data were used to quantify the bubbles characteristics while the air moisture content was used to calculate the drying rate. To avoid the complexity of the process, the fluidised bed was operated at single bubbling regime. The experimental results are discussed in relation to the different drying mechanisms.

Waste Edible Oil Fluid Catalytic Cracking In A Downer Reactor, Xiaoping Tang, Fei Wei

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

The waste edible oil fluid catalytic cracking process (FCC), an environment friendly process to produce clean fuel (such as gasoline, diesel) and high-value chemical materials (such as propylene), was studied in an small hot model of downer reactor under the temperature 500 ℃, the pressure 1.1×105Pa , the resident time 1 second, the ratio of catalyst to oil 12 , and MA-83 as the catalyst. Compared with other processes, the waste edible oil FCC process can realize the waster utilizing and adjust the product distribution according to the market demand, while with a convenient pretreatment to the raw materials. The …

Simulation Of A Pulsating Bed Using Eulerian Approach, Shyam Shankar Dokka, Hamid Arastoopour

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

A numerical study of the effect of gas pulsation on the flow pattern of solid particles in a two-dimensional gas-solid fluidized bed was conducted using the Eulerian granular kinetic theory. Our simulated bed dynamics agreed well with the experimental work of Koksal and Vural, and with the Discrete Element Method (DEM) model simulations of Tsuji et al.

A Discrete Particle Simulation Study Of Solids Mixing In A Pressurized Fluidized Bed, Willem Godlieb, Niels G. Deen, J.A.M. Kuipers

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

A fluidized bed containing polymeric particles is investigated using a state-of-the-art soft-sphere discrete particle model (DPM). The pressure dependency of particle mixing, flow patterns and bubble behaviour are analysed. It is found that with increasing pressure a less distinct bubble-emulsion structure and improved solids mixing can be observed.

Approximate Prediction Of Gas-Solid Conversion In Fluidized Bed Reactors, Alberto Gómez Barea, B. Leckner, M. Campoy

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

A simple method is proposed to evaluate the performance of fluidized bed reactors where an nth-order gas-solid reaction occurs. The method takes into account the fluid dynamics of the fluidized bed by a two-phase flow model and the rates of diffusion in the solid reactant particles (internal and external) by a simple particle model. Approximate analytical expressions are derived in terms of three effectiveness factors: interphasic, external and intraparticle. These account for the contribution of fluid-dynamic and diffusional resistances to the overall mass-transfer resistance. Gas conversion is expressed in terms of four dimensionless governing quantities and the reaction order, in …

A Rotating Fluidized Bed In A Static Geometry: Experimental Proof Of Concept, Juray De Wilde, Luc Wautier, Guy B. Marin, Geraldine J. Heynderickx, Axel De Broqueville

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

The new concept of a rotating fluidized bed in a static geometry (RFB-SG) is presented (1). The rotating motion of the particle bed and the tangential fluidization of the solids are obtained by the tangential injection of the fluidization gas via multiple gas inlet slots in the outer cylindrical wall of the fluidization chamber. The new fluidization concept is experimentally investigated and proven using either large diameter, low density polymer particles or small diameter, higher density Alumina particles.

Influence Of Bubble-Bubble Interactions On The Macroscale Circulation Patterns In A Bubbling Gas-Solid Fluidized Bed, J. A. Laverman, M. Van Sint Annaland, J.A.M. Kuipers

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

The macro-scale circulation patterns in the emulsion phase of a gas-solid fluidized bed in the bubbling regime have been studied with a 3D Discrete Bubble Model. It has been shown that bubble-bubble interactions strongly influence the extent of the solids circulation and the bubble size distribution.

An Analysis Of Pressure Fluctuations In A Cfb Of Heavy Minerals, Adam Luckos, Quinn G. Reynolds , Paul Den Hoed

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

Pressure fluctuations were measured at high frequencies in a CFB model operated with air at ambient conditions. The model comprises an 80-mm-ID, 5-m-tall riser with a blind-T exit, a cyclone, a 50-mm-ID standpipe, and an L-valve. Tests were conducted with particles of natural rutile (TiO2), a heavy mineral mined from coastal dunes. The particles fall into group B of Geldart’s classification. The solids inventory was kept at 25 kg. The superficial gas velocity ranged from 3 to 6 m/s. The solid circulation flux varied between 10 and 40 kg/m2.s.

Profiles of solid concentrations in the riser are C-shaped. The amplitude …

Title Page - Table Of Contents - Preface - List Of Reviewers, Xiaotao T. Bi, Franco Berruti, Todd S. Pugsley

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

No abstract provided.

Improved Standpipe Entrance For Stable High-Flux Flow, D. Rusnell, John R. Grace, Xiaotao T. Bi, C. Jim Lim, P. Ronan, C. A. Mcknight

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

Cold model tests were used to show the causes of instabilities in the operation of the standpipe entrance (“sore thumb”) in industrial scale fluid cokers. New geometries were tested which might provide higher flows and prevent operating problems such as flow reversals and flooding, while also minimizing the adverse effects of fouling. The tests were conducted using FCC particles in a geometrically and dynamically scaled half-column of approximately 1/9th scale which had previously been used to show the effects of baffles on fluid coker strippers. The addition of sloping surfaces to increase the surface area for ingress of particles was …

Hydrodynamic Scale-Up Of Circulating Fluidized Beds, Ted Knowlton, S. B. Reddy Karri, J. S. Smith

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

A general procedure that can be used to scale up circulating fluidized beds is presented. It consists of developing a mathematical model in conjunction with measuring 1) the radial dispersion coefficient (Dr) using gas tracers, 2) the radial solids velocity profile using a Pitot tube and 3) the radial distribution of solids density (1 - ε) using an optical probe. If the resulting information is obtained in a riser 200 mm or greater in diameter, it can be used in conjunction with the mathematical model for scale-up.

Subject Index, Xiaotao T. Bi, Franco Berruti, Todd S. Pugsley

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

No abstract provided.

Measuring The Gas-Solids Distribution In Fluidized Beds - A Review, J. Ruud Van Ommen, Robert F. Mudde

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

This paper reviews techniques for measuring the voidage distribution in gas-solid fluidized beds, with a focus on the developments during the last ten years. Most attention is given to recent progress in tomography and pressure measurements, but visual observations, capacitance probes and optical probes are also covered.

Presentation Slides: Hydrodynamic Scale-Up Of Circulating Fluidized Beds, Ted Knowlton

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

No abstract provided.

Analytical Multi-Scale Methodology For Fluidization Systems - Retrospect And Prospect, Jinghai Li, Wei Ge, Jiayuan Zhang, Shiqiu Gao, Wei Wang, Ning Yang, Qicheng Sun, Jian Gao

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

Understanding the spatio-temporal multi-scale structure of fluidization is a challenging problem. This presentation reviews our 20-year efforts on this subject, showing the roadmap that has gradually evolved from a simple idea to a systematic methodology inclusive of subsidiary, related systems and industrial applications. The strategy of establishing stability conditions through analyses of the compromise between dominant mechanisms is emphasized. The presentation concludes with prospects for further theoretical explorations and industrial applications.

Presentation Slides: Analytical Multi-Scale Methodology For Fluidization Systems - Retrospect And Prospect, Jinghai Li

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

No abstract provided.

Presentation Slides: Fluidized Bed Combustion For Clean Energy, Filip Johnsson

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

No abstract provided.

Presentation Slides: Measuring The Gas-Solids Distribution In Fluidized Beds - A Review, J. Ruud Van Ommen

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

No abstract provided.

Fluidized Bed Combustion For Clean Energy, Filip Johnsson

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

This paper gives a brief overview of the status and prospects for fluidized bed combustion (FBC) for clean energy, with focus on power and heat generation. The paper summarizes recent development trends for the FB technology and makes an outlook into the future with respect to challenges and opportunities for the technology. The paper also identifies areas related to fluidization, which are critical for the technology and, thus, will require research. The main advantage with the FBC technology is the fuel flexibility. A compilation of 715 FB boilers (bubbling and circulating) worldwide illustrates the two main applications for the FBC …

Solids Flux, Velocity And Local Solid Fraction Measurements In A Cfb Riser, Ronald W. Breault, Christopher Guenther

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

In this investigation a fiber-optic probe and an extraction solids probe are used to measure particle velocities and solids flux values. These are subsequently used to determine the local solids fractions as a function of radial position in a cold flow circulating fluidized bed (CFCFB) in operation at the National Energy Technology Laboratory (NETL). Measurements were taken under several separate operating conditions ranging from dilute up-flow to core-annular flow to fast fluidization using nominal 800 micron cork particles. The solids properties and test operating conditions were chosen particularly to provide dynamic similitude between the test data and the operation of …

Analysis Of Heat Transfer Between Two Particles For Dem Simulations, Kenya Kuwagi, Muhammad Arif Bin Mokhtar, Toshihiro Takami, Masayuki Horio

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

The purpose of the present study was to develop a model of heat transfer between particles that can be incorporated into the discrete element method (DEM). The flow around a particle was measured by particle imaging velocimetry (PIV) and the temperature of the particle was measured using a thermocouple and an infrared camera. The experimental data of heat transfer were classified according to the heat transfer mechanism, namely convection, conduction and contact. These values for heat transfer were compared with those calculated using previously derived estimation equations. From these results, we adopted the thermal contact resistance model, which is related …

Numerical Investigation Of The Layer-Inversion Phenomenon In Binary Solid Liquid Fluidized Beds, Kevin F. Malone, Bao H. Xu, Michael Fairweather

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

Layer inversion behaviour in binary-solid liquid fluidized beds is examined using a Combined Continuum and Discrete Model. A suitable bidisperse system was selected from information in the literature. By simulating the fluidization of the system at a range of liquid velocities, varying degrees of segregation and mixing have been observed.

Flow Characteristics Of Fully Wetted Binary Solid Mixtures In Gas Fluidized Beds With Inclined Gas Distributors, Yusumi Nagahashi, John R. Grace, Norman Epstein, Yutaka Asako, Akira Yokogawa

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

A unique gas-fluidized bed in which fluidization is enhanced by adding a little water has potential for soft abrasive washing of various products. Preliminary experiments were carried out for the washing of farm products. Gas fluidized beds of binary solids mixtures with inclined gas distributors provide hydrodynamic and mixing data assisting the design of dry and wet gas-fluidized beds.

Mechanistic Study Of Nano-Particle Fluidization, X. S. Wang, F. Rahman, Martin J Rhodes

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

Degussa Aerosil R974 powder, with a primary particle size of 12 nm, was fluidized using nitrogen in a cylindrical vessel, 50-mm-id and 900 mm in height. Characteristics of incipient fluidization are analysed in relation to variations in the initial packing conditions. Bed collapse experiments were performed and the results are used for assessing fluidization characteristics of the particles. It was found that nanoparticles exhibit characteristics of both Group A and Group C powders. Various methods for estimating the cohesion forces between nanoparticle aggregates are discussed.

Hydrodynamic Effects Of Particle Chaining In Liquid-Solid Magnetofluidized Beds, Carlos F. Cruz-Fierro, Brian P. Reed, Joaquin Pinto-Espinoza, Goran N. Jovanovic

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

In a fluidized bed of magnetically susceptible particles, the presence of a magnetic field induces particle chaining due to interparticle magnetic forces. The particle chains offer less resistance to flow, resulting in a decrease of the drag coefficient. The change in drag coefficient as a function of hydrodynamic and magnetic operating conditions of a liquid-solid magnetofluidized bed is studied.

Multiple Particle Tracking In A Fluidised Bed, A. Ingram, Z. Yang, S. Bakalis, D. J. Parker, X. Fan, P. J. Fryer, J. P.K. Seville

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

Positron Emission Particle Tracking (PEPT) is a versatile method for following the motion of a single radioactive tracer particle in a fluidised bed. However, there are many applications in which it would be useful to be able to follow the motion of two or more particles simultaneously in cooperative motion. The tracers are labelled with different intensities of radiation and located by converging sequentially on centres of activity. Two 600&#;m polyethylene particles have been followed in a 15 cm diameter bed and their contact events studied.

Detection Of Oversized Material In A Hydrotransport Slurry Pipe Using Non-Invasive Acoustic Method, Katherine Albion, Joesph Downey, Erin Hansuld, Derek Hartling, Lauren Briens, Franco Berruti, Steven Mcdougall

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

Large material, such as rocks, in a hydrotransport system of fine particles can damage pumps and equipment. A reliable, non-intrusive, and on-line acoustic method was developed for the detection of this large material. Analysis of signals recorded by microphones attached to the pipe wall allows for the reliable detection of rocks of different sizes and shapes, with no false positives.

Tapered Fluidized Beds And The Role Of Fluidization In Mineral Emplacement, Thomas M. Gernon, Mark A. Gilbertson, R. Stephen J. Sparks, Matthew Field

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

One of the most prominent features of fluidized beds is their ability to mix and segregate. This is of great importance for many industrial processes, but takes on a particular significance for mineral extraction where a small amount of valuable matter is mixed with a large amount of waste. In this study we consider the occurrence of diamonds in the volcanic rock called “kimberlite”. These are often emplaced (erupted and deposited) in large volcanic pipes commonly referred to as “diatremes” (length scale of the order of a kilometre) with a vent at the bottom through which the minerals were introduced …

A Dem Study Of Geldart Group A Particle Bed Fluidisation Behavior Across The Regimes, Fang Yang, David K. Kafui, C. Thornton, J.P.K. Seville

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

The objective of the study is to identify the transitions in bed behavior as the gas velocity is increased to cover the complete range from minimum fluidization through bubbling and turbulent behavior to pneumatic transport. The simulation data is examined in terms of computer visualizations, the rate of change of average bed voidage and pressure drop fluctuations.