Spheres vs. rods in fluidized beds: Numerical and experimental investigations

For the past century, fluidized beds have been standard equipment in many branches of industry. In most applications they are used to manipulate granular and powder-like materials, whose particles can roughly be approximated as spheres. Therefore, numerical models and investigations have focused mainly on fluidized beds with spherical particles....

Aggregation Phenomena in Atomic Layer Deposition: Bridging Macro and Nano

Atomic layer deposition (ALD) is a gas-phase thin film technology that boasts atomic-level control over the amount of material being deposited. A great deal of research effort has been devoted to the exploitation of ALD precision for the synthesis of nanostructures other than thin films such as supported nanoparticles (NPs). ALD is not only...

Towards the production of core-shell nanoparticles with fluidized bed ALD

Reducing particle size or material structure size to nanometer scale can make the material properties, such as light absorption and electronic structure, change compared to the same materials at normal scale. This gives them properties that can make them suitable for the development of highly efficient and improved micro-electronics, sensor...

Gas Jets in Granular Matter: Observed by a High Speed X-ray Tomography System

High speed X-ray tomography is a promising tool to visualize the time-resolved gas distribution for fluidized beds. The tomography unit at Delft University of Technology is composed of three X-ray tubes and three double-layer detector arrays. The X-ray tubes are places at 120? around the fluidized bed. The detector arrays are placed opposite to...

On the gasification of biomass in a steam-oxygen blown CFB gasifier with the focus on gas quality upgrading: Technology background, experiments and mathematical modeling

This work presents and discusses the results of the research on the gasification of biomass in an atmospheric circulating fluidized bed, with a mixture of steam and oxygen as fluidization / gasification medium. The main objectives of this research were to investigate and improve the gasification process in order to produce hydrogen-rich gas from...

Agglomeration in fluidized beds: Detection and counteraction

Fluidized beds comprise a quantity of solid particles that is suspended by an upward flowing gas. They are used for a variety of processes in the chemical industry, such as catalytic reactions, drying, coating and energy conversion. A major problem in industrial practice is the occurrence of unwanted agglomeration, i.e. solid particles adhering...

Distributed secondary gas injection via a fractal injector: A nature-inspired approach to improving conversion in fluidized bed reactors

The conversion in bubbling fluidized bed reactors is suppressed because the interphase mass transfer and gas-solid contact in bubbling fluidized bed reactors are often poor. Most of the gas is present in the form of bubbles, which have low surface-to-volume ratios and are nearly devoid of catalyst particles. The chaotic behaviour of the bubbles...

Learning to simulate and predict chaotic dynamical systems

With precise knowledge of the rules which govern a deterministic chaotic system, it is possible to interact with the system and change its dynamics. This research is part of a larger project, in which chaos control is used to improve the bubbling behavior of multi-phase chemical reactors. Chaos control requires models which capture the complete...

Conceptual design of a fluidized bed nuclear reactor: Statics, dynamics and safety-related aspects

In this thesis a conceptual design of an innovative high temperature reactor based on the fluidization principle (FLUBER) is proposed. The reactor should satisfy the following requirements: (a) modular and low power, (b)) large shutdown margin, (c) able to produce power when the bed of particles expands and stop as soon as the coolant flow is...

Fluidized bed heat exchangers to prevent fouling in ice slurry systems and industrial crystallizers

Ozon layer depletion and global warming by synthetic refrigerants forces refrigeration industries to switch over to natural but hazardous refrigerants like ammonia and hydrocarbons. A promising technology to safely use the latter refrigerants is the application of indirect refrigeration systems with ice slurry as heat transfer fluid. Ice slurry,...

Electric-field enhanced fluidized beds: A low-energy bubble control method

Reducing the size of gas bubbles can significantly improve the performance of gas-solid fluidized beds one of the most common reactor types in the chemical industry applied for such diverse systems as gasoline and plastics production to foods processing. However, a control of bubbles in these reactors is difficult to realize without measures...

Scales and structures in bubbly flows. Experimental analysis of the flow in bubble columns and in bubbling fluidized beds

In this project a detailed experimental analysis was performed of the dynamic flow field in bubbly flows, with the purpose of determining local hydrodynamics and scale effects. Measurements were done in gas-liquid systems (air-water bubble columns) and in gas-solid systems (air-sand bubbing fluidized beds) of different size. Amongst others with...

Monitoring Fluidized Bed Hydrodynamics

Derivation, Implementation, and Validation of Computer Simulation Models for Gas-Solid Fluidized Beds

The chemistry in the freeboard of a coal-fired pressurized fluized bed combustor

The Interconnected Fluidized Bed reactor - for gas/solids regenerative processes

Chaotic hydrodynamics of fluidized beds

The Fluid Dynamics of the Freeboard in a Fluidized Bed Reactor