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,...

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...

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...

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...

The Fluid Dynamics of the Freeboard in a Fluidized Bed Reactor

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

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...

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...

Fluidized Bed Gasification as a Mature And Reliable Technology for the Production of Bio-Syngas and Applied in the Production of Liquid Transportation Fuels: A Review

Biomass is one of the renewable and potentially sustainable energy sources and has many possible applications varying from heat generation to the production of advanced secondary energy carriers. The latter option would allow mobile services like the transportation sector to reduce its dependency on the fossil fuel supply. This article reviews...

Feasibility study of a time-resolving x-ray tomographic system

Deposition of conductive TiN shells on SiO2 nanoparticles with a fluidized bed ALD reactor

Conductive TiN shells have been deposited on SiO2 nanoparticles (10–20 nm primary particle size) with fluidized bed atomic layer deposition using TDMAT and NH3 as precursors. Analysis of the powders confirms that shell growth saturates at approximately 0.4 nm/cycle at TDMAT doses of >1.2 mmol/g of powder. TEM and XPS analysis showed that all...

On the fluidization of cohesive powders: Differences and similarities between micro- and nano-sized particle gas–solid fluidization

The fluidization of cohesive powders has been extensively researched over the years. When looking at literature on the fluidization of cohesive particles, one will often find papers concerned with only micro- or only nano-sized powders. It is, however, unclear whether they should be treated differently at all. In this paper, we look at...

The Mechanism behind Vibration Assisted Fluidization of Cohesive Micro-Silica

Vibro-assisted fluidization of cohesive micro-silica has been studied by means of X-ray imaging, pressure drop measurements, and off-line determination of the agglomerate size. Pressure drop and bed height development could be explained by observable phenomena taking place in the bed; slugging, channeling, fluidization or densification. It...

Fluidization of elongated particles—Effect of multi-particle correlations for drag, lift, and torque in CFD-DEM

Having proper correlations for hydrodynamic forces is essential for successful CFD-DEM simulations of a fluidized bed. For spherical particles in a fluidized bed, efficient correlations for predicting the drag force, including the crowding effect caused by surrounding particles, are already available and well tested. However, for elongated...