Fluidization

Fluidized-bed technology has received a growing interest and it use has increased almost exponentially over the past few decades, in commercial
applications such as chemical industry in the fluidized catalytic cracking of petroleum feedstock among other applications, also the development of the synthetic fuels industry, fluidized reactor systems are being considered and are employed for coal and more recently biomass gasification and pyrolysis.Other current operations include combustion, drying and coating technology.
 

2-D fluidized bed

In 2-D fluidized beds a very popular technique is direct visualization that allows measuring the particles distribution very accurately. Applying further processes to the images obtained with the help of normal/high-speed camera, particle velocities can also be calculated. As a relevant results of this technique, the 2-D fluidized bed allowed the characterization of the through-flow within bubbles. However this technique cannot be used in 3-D fluidized beds. ISE research group have been used two non-intrusives techniques: Particle Image Velocimetry (PIV) and Digital Image Analysis (DIA), to characterize the fluidized bed behaviour.

 

Motion of objects immersed in bubbling fluidized beds

Most ofthe applications of fluidized beds involve the motion of objects inside the bed. Fuel particles, catalysts, and agglomerates are examples of typical objects found inside a fluidized bed. It is mandatory to characterize the motion of these objects within the bed to establish the region of proper performance and to prevent operational problems such as the existence of hot or cold spots in a reactor or the appearance of de-fluidized zones due to the existence of agglomerates. We study the motion of objects in a 2D fluidized bed where the whole path of the object can be analyzed and modeled. Such a modeling of the object motion in a 2D bed is intended to extrapolate to objects moving in a 3D bed. In the 3D bed, the rotation of the distributor has a strong effect on the object motion.

 
 
 
 

Fluidized bed modelling

In order to understand fluidized bed dynamics and develop models useful to guide design and operation of fluidized beds. The ISE group explore different modelling approximation which moves from detailed CFD and DEM models to the most general phenomenological and mechanistically descriptions of the flow.

CFD Two-fluid modelling

One of the research areas of the ISE group is the CFD modelling of fluidization systems. It is mainly focused on basic research of fluidization hydrodynamics, which is aided by the experimental facilities of the group.

Modelling strategies in fluidized beds has advanced significantly over the last two decades, being the two-fluid modelling the most popular approach. The research line of the ISE Group is based on the comparison and validation of two-fluid model, comparing it with the data acquired with our experimental facilities.

DBM modelling (Phenomenological)

Focused on the discrete bubble modelling of large bubbling gas-solid fluidized in order to help design and operation of gas- solid fluidized bed as well as to characterize large-scale mixing behaviour, feeding issues, bed geometry, operating conditions, distributor design, etc.

DEM modelling

Aimed to describe the segregation and mixing mechanism occurring in fluidized and vibrated beds at particle level.

 

 

Vibrofluidization

The vibrofluidized bed system combines the vibratory technology with the conventional fluidized bed. It is mainly used for processes with low flow rate of sweep gas, wide particle diameter distribution, particles type C of Geldart’s classification, and coating.

ISE research line is focused on the characterization of the vibration motion in the bed, and to obtain the optimum operation conditions.

 
 


Vertical axis rotating distributor fluidized bed

The vertical-axis rotating distributor is a perforated plate that rotates around the vertical axis of the column as it is coupled to the shaft of an AC electric motor.

The novel design is aimed to improve the radial gas and particle mixing and to achieve a more uniform fluidization.

With the rotating configuration smaller and more uniformly distributed bubbles have been measured.

 
 
 

Engineering and advanced control of gas-solid fluidized beds

This research line deals with the problematic issue of fluidized bed dynamics, whose complexity justified the needs of new strategic approaches for making progress on dynamics and control knowledge of gas-solid fluidized beds of industrial interest.

New conceptual approaches addressed to Engineer the Hydrodynamic of Gas solid fluidized bed are applied to understand the scientific as well as the engineering aspects of fluidized systems that appear during their scale-up process and later industrial applications. The present line is intended to extend and to improve de current tools for design, modeling, controlling and scaling-up industrial gas-solid fluidized beds by developing and applying novel methods and techniques that account for the nonlinear dynamics exhibited by fluidized bed systems, such as those derived from both the deterministic chaos and the information theory.

The current project on this topic address the following areas of application

• Development of non-intrusive measurement techniques for monitoring fluidized bed dynamics, to be applied in processes performed under severe corrosive, high pressure or high temperature conditions, such as those carried out in fluidized bed combustors.
• Structuring gas-solid fluidized bed dynamics by means of rotating distributors, mechanical vibrations and air injection pulse.
• Development of monitoring methods and advanced data treatment techniques for on-line monitoring and dynamic diagnosis of gas solid fluidized beds. This research comprises the integration of classical characterization methods with the most sophisticated and advanced existing methodologies for dynamic diagnosis and multi-scale analysis.

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