This document provides an introduction to fluidized beds, including their components, advantages, disadvantages, applications, and flow regimes. It describes how fluidized beds are composed of a solid material (typically a catalyst) that is fluidized by a gas or liquid. The document outlines the main flow regimes - bubbling, turbulent, and fast fluidization - and discusses factors that influence transitions between regimes like pressure, temperature, and particle properties. It also provides examples of industrial processes using fluidized beds and references for further reading.
Fluidized Bed Reactor - Basic Mechanism, Mass Transfer in Fluidized Beds, Reaction Behaviour in a Fluidized Bed, Mole Balance on the Bubble, the Cloud, and the Emulsion, Advantages & Disadvantages, Current Applications of FBR.
Fluidized Bed Reactor - Basic Mechanism, Mass Transfer in Fluidized Beds, Reaction Behaviour in a Fluidized Bed, Mole Balance on the Bubble, the Cloud, and the Emulsion, Advantages & Disadvantages, Current Applications of FBR.
The processing technique employing a suspension or fluidization of small solid particles in a vertically rising stream of fluid usually gas so that fluid and solid come into intimate contact. This is a tool with many applications in the petroleum and chemical process industries. Suspensions of solid particles by vertically rising liquid streams are of lesser interest in modern processing, but have been shown to be of use, particularly in liquid contacting of ion-exchange resins. However, they come in this same classification and their use involves techniques of liquid settling, both free and hindered (sedimentation), classification, and density flotation.
WHAT IS SEDIMENTATION?
TYPES OF SEDIMENTATION
TYPES OF SETTLING
BATCH SEDIMENTATION
RATE OF SEDIMENTATION
APPLICATIONS OF SEDIMENTATION
EQUIPMENTS USED FOR BATCH SEDIMENTATION
THICKENERS
CLARIFIERS
Absorption & indusrial absorber,Gas Absorption,Equipments,Absorption in chemical Reaction,Absorption in Packed Tower,Absorption for counter current,Choice of Solvent,Continuous Contact Equipment,Height Equivalent to Theoretical Plate,HETP
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Mass transfer processes
Subject: 3.2 Equipment
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The processing technique employing a suspension or fluidization of small solid particles in a vertically rising stream of fluid usually gas so that fluid and solid come into intimate contact. This is a tool with many applications in the petroleum and chemical process industries. Suspensions of solid particles by vertically rising liquid streams are of lesser interest in modern processing, but have been shown to be of use, particularly in liquid contacting of ion-exchange resins. However, they come in this same classification and their use involves techniques of liquid settling, both free and hindered (sedimentation), classification, and density flotation.
WHAT IS SEDIMENTATION?
TYPES OF SEDIMENTATION
TYPES OF SETTLING
BATCH SEDIMENTATION
RATE OF SEDIMENTATION
APPLICATIONS OF SEDIMENTATION
EQUIPMENTS USED FOR BATCH SEDIMENTATION
THICKENERS
CLARIFIERS
Absorption & indusrial absorber,Gas Absorption,Equipments,Absorption in chemical Reaction,Absorption in Packed Tower,Absorption for counter current,Choice of Solvent,Continuous Contact Equipment,Height Equivalent to Theoretical Plate,HETP
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Mass transfer processes
Subject: 3.2 Equipment
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Fluidization Characteristics of Nano Particles with the Assist of StirrerIOSR Journals
Fluidization of ultrafine solid particles is widely used in a variety of industrial applications because of its
unusual capability of continuous powder handling, good mixing, large gas–solid contact area, and very high rates of
heat and mass transfer. As the particle size decreases the cohesive forces between particles increases. Therefore,
fluidization of ultrafine particles becomes much more difficult as compared to the larger size particles and it needs efficient method. In the present work, the fluidization experiments were conducted using air as fluidizing media and SiO2, ZnO and Al2O3
nano particles, with a size ranging from 15 to 30 nm in 2-dimensional fluidized bed with the assist of stirrer.
The fluidization behavior of the nanoparticle, including the fluidization regime, the minimum fluidization velocity, and the
bed expansion are also investigated. . The results showed that smoother fluidization was observed with increasing agitation
speed, because the agglomeration and channeling were reduced by the mechanical agitation. It was found that with the assist of stirrer ,by increasing in the speed of stirrer initial bed voidage increased and terminal velocity and agglomerate diameter decreased.
Improving Operability of Lab-Scale Spouted Bed Using Global Stochastic Optimi...IJERA Editor
A spouted bed is a special case of fluidization. It is an effective means of contacting gas with coarse solid particles .Gas-solid spouted beds are either cylindrical bed with cone base or the whole bed is in a cone shape where the gas enters as a jet. The gas forms a spout region that carries the solids upward in a diluted phase that forms a fountain at the top of the bed where the solids fall down and move downward in the annular region. Performance of gas-solid spouted bed benefit from solids uniformity structure with lower pressure drop (PD).Dropping of PD across a spouted bed could reduce the dissipated pumping energy and improve stability and uniformity of solid particles. The objective of this work is to study and selecting best operating conditions that could minimize PD across the bed. Optimization technique is a powerful tool would guide the experimental work and reduce the risk and cost for design and operation Hence, PD is to be considered as objective function of the optimization process .Three selected decision variables are affecting objective function. These decision variables are gas velocity, particle density and particle diameter. Steady-state measurements were carried out in a narrow 3-inch (0.076 m ID) cylindrical spouted bed made of Plexiglas that used 60° conical shape base. Radial concentration of particles (glass and steel beads) at various bed heights under different flow patterns were measured using sophisticated optical probes. A superficial velocity of air ranging from 0.74 to 1.0 m/s .PD was measured across the bed by high accuracy pressure transducers. Stochastic Genetic Algorithm (GA) has found suitable global search for the non-linear hybrid spouted bed. Optimum results could select the best operating conditions for high-performance and stable conditions. Uniformity and stability of solid particles in the bed would enhance hydrodynamic parameters, heat and mass transfer. Best Operability of the bed was observed with low-density, large size of solid beads, low gas velocity at low PD. Size of solid particles and velocity of gas have been found the sensitive decision variables with PD mutations. Sensitivity of these variables could be increased at unlimited upper bounds of operating conditions. An advanced control system for sensitive decision variables would be recommended to improve operability of the spouted bed.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Pressure effects on gas-solid fluidized bed behaviorIgor Sidorenko
Sidorenko, I., & Rhodes, M. J. (2003) Pressure effects on gas-solid fluidized bed behavior. International Journal of Chemical Reactor Engineering, 1, R5.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
The influence of pressure on fluidized bed behaviourIgor Sidorenko
Sidorenko, I., & Rhodes, M. J. (2002) The influence of pressure on fluidized bed behaviour. Paper presented at the World Congress on Particle Technology 4, Sydney.
Similar to Fluidized bed introduction by mohabat ali malik(MUET,jamshoro) (20)
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3. Fluidized Bed Reactor Components
Inlet to cyclone
The material fluidized is a solid (catalyst).
The fluidizing medium is either
a gas or a liquid.
Gas distributor
CHEMICAL REACTION ENGINEERING LABORATORY
4. Advantages
It has the ability to
process large volumes
of fluid.
Excellent gas-solid
contacting.
Heat and mass transfer
rates between gas and
particles are high when
compared with other
modes of contacting.
No hot spot even with
highly exothermic
reaction.
Ease of solids handling.
Disadvantages
Broad or even bimodal
residence time
distribution of the gas
due to dispersion and
bypass in the form of
bubbles.
Broad residence time
distribution of solids due
to intense solids mixing.
Erosion of internals.
Attrition
of
catalyst
particles.
Difficult Scale-up due to
complex hydrodynamics.
CHEMICAL REACTION ENGINEERING LABORATORY
5. Industrial Applications of Fluidized Bed Reactor
Acrylonitrile by the Sohio Process.
Yang 2003
Fischer-Tropsch Synthesis.
Phthalic anhydride synthesis.
Methanol to gasoline and olefin processes.
Cracking of Hydrocarbons (Fluid Catalytic Cracking, etc).
Coal combustion.
Coal gasification
Cement clinker production.
Titanium dioxide production.
Calcination of AL(OH)3.
Granulation drying of yeast.
Heat exchange
Absorption
Nuclear energy (Uranium processing, nuclear fuel fabrication,
reprocessing of fuel and waste disposal).
CHEMICAL REACTION ENGINEERING LABORATORY
7. Geldart's Classification of Powders
Group A (Aeratable)
:- (e.g.,
Ammoxidation of propylene) small
mean particle size and/or low particle
density (<~1.4 g/cm3), gas bubbles
appear at minimum bubbling velocity
(Umb).
Group B (Sand-Like) :- (e.g.,Starch)
particle size 40 μm to 500 μm and
density 1.4 to 4 g/cm3, gas bubbles
appear at the minimum fluidization
velocity (Umb).
Kunii and Levenspiel (1991)
kg^ 3
Group C (Cohesive)
:- very fine
particle, particle size < 30 μm, difficult
to fluidize because inter-particle
forces are relatively large, compared
to those resulting from the action of
gas.
Group D (Spoutable) :- (e.g., Roasting
coffee beans) large particle, stable
spouted beds can be easily formed in
this group of powders.
Diagram of the Geldart classification of
particles, Geldart (1973 ).
8. Flow Regimes in Fluidized Beds
J. Ruud van Ommen, 2003
CHEMICAL REACTION ENGINEERING LABORATORY
9. Minimum Fluidization Velocity
This equation can be used to calculate the minimum fluidization velocity
U if the void fraction εmf at incipient fluidization is known.
mf
2
f umf
p f g
3
s D p mf
150 mf
1
1.75
s D p umf f
Experimentally, the most common method of measurement requires that pressure drop
across the bed be recorded as the superficial velocity is increased stepwise through Umf
and beyond, Umf is then taken at the intersection of the straight lines corresponding to
the fixed bed and fluidized bed portions of the graph obtained when Pbed is plotted
against U on log-log coordinates.
Kunii and Levenspiel (1991)
10. Bubbling Fluidization
This type of fluidization has
been called ‘aggregative
fluidization’, and under
these conditions, the bed
appears to be divided into
two phases, the bubble
phase and the emulsion
phase.
The bubbles appear to
be very similar to gas
bubbles formed in a
liquid and they behave
in a similar manner. The
bubbles coalesce as
they rise through the
bed.
CHEMICAL REACTION ENGINEERING LABORATORY
11. Turbulent Fluidization
Turbulent regime has the following features: High solid hold-ups (typically 25-35 %
by volume).
Limited axial mixing of gas.
Suitable for exothermic and fast
reactions.
Good gas-solid contact and hence,
favors reactant conversion.
high gas flow-rates operation and good
for isothermal operation.
Favorable bed to surface heat transfer.
Canada et al. 1978
CHEMICAL REACTION ENGINEERING LABORATORY
12. Some commercial processes in turbulent
fluidization
Process
Particle classification
Typical gas velocity
(m/s)
FCC regenerators
Group A
0.5-1.5
Acrylonitrile
Group A
~0.5
Maleic anhydride
Group A
~0.5
Phthalic anhydride
Group A
~0.5
Ethylene dichloride
Group A
~0.5
Roasting of zinc sulfide
Group A
~1.5
Bi et al. 2000
CHEMICAL REACTION ENGINEERING LABORATORY
13. Fast Fluidized Bed
The fast fluidization occurs as a result of
continuing increasing in operating velocity
beyond that required at turbulent
fluidization, a critical velocity, commonly
called the transport velocity (Utr), will be
reached where a significant particle
entrainment occurs.
The CFB has significant industrial
applications because of its efficiency,
operational
flexibility,
and
overall
profitability (Berruti et al., 1995).
CHEMICAL REACTION ENGINEERING LABORATORY
14. Transition between Fluidization Regimes.
Grace (1986a) summarized the effects of particles properties and operating conditions
on fluidization behavior and prepared a flow regime diagram. The flow regime diagram
was further modified by Kunii and Levenspiel (1997).
For given particles and operating velocity, the gas-solid contact pattern can be
determined using this diagram. Likewise, for a given flow regime, this diagram could
provide available combinations of particle properties and gas velocity.
Yang 2003
16. Methods for Regime Transition Identification
Several measurement methods have been utilized to
determine the transition from bubbling or slugging to
turbulent fluidization which can be classified into three
groups:-
Visual Observation,.
Pressure Drop-versus Velocity diagram.
local and overall bed expansion.
Based on signals from pressure transducers, capacitance
probes, optical fiber probes, X-ray facilities.
Bi et al. 2000
CHEMICAL REACTION ENGINEERING LABORATORY
17. Generalized effect of operating and design parameters on
flow regime transition
Parameter
Effect on flow regime transition
Pressure
In general, pressure accelerates the flow regime transition, thereby decrease
transition velocity (Lanneau , 1960, Cai et al. 1989, Yates 1996).
Temperature
Transition velocity increases as the temperature is increased, (Peeler et al.,
1999, Cai et al., 1989 and Foka et al., 1996).
Static Bed Height
The transition velocity was almost independent of the static bed height, which
varied from 0.4 to 1.0 m (Grace and Sun 1990). Similar results were reported by
Cai (1989) and Satija and Fan (1985) with (Hmf/Dt) > 2. On the other hand, for
a shallow fluidized bed of (Hmf/Dt) < 2 with Group B and D particles, Canada et
al. (1978) and Dunham et al. (1993) found that Uc increased with static bed
height. This could be related to the undeveloped bubble flow in shallow beds
before transition to turbulent fluidization can occur (Bi et al. 2000).
Particle Size and
Density
Uc increases with increasing mean particle size and density (Cai et al. 1989, Bi
et al. 2000).
Column Diameter
Transition velocity decreases with increasing column diameter for small column,
becoming insensitive to column diameter for Dt > 0.2 m, (Cai, 1989). Similar
trends were observed by (Zhao and Yang, 1991) with internals.
Internals
Transition to turbulent fluidization tends to occur at lower gas velocities in the
presence of internals which usually restrict bubble growth and promote bubble
breakup.
18. Effect of column diameter
Cai (1989)
Uc decreases with increasing column diameter for small columns
(less than 2 m), becoming insensitive to column diameter for Dt >
0.2 m.
Similar trends were observed by Zhao and Yang (1991) in
columns with internals.
CHEMICAL REACTION ENGINEERING LABORATORY
19. Some Selected References
Cai et al., 1989, “Effect of operating temperature and pressure on
the transition from bubbling to turbulent fluidization”, AICHE
Symposium series, 85, 37-43.
Chehbouni et al., (1994), “Characterization of the flow transition
between bubbling and turbulent fluidization”, Ind. Eng. Chem. Res.,
33, 1889-1896.
Bi et al., (2000), “A state-of-art review of gas-solid turbulent
fluidization”, Chemical engineering science, 55, 4789-4825.
Andreux et al. (2005), “New description of fluidization regimes”,
AICHE Journal, 51, No.4, 1125-1130.
CHEMICAL REACTION ENGINEERING LABORATORY