A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions.
In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough velocities to suspend the solid and cause it to behave as though it were a fluid.
This process, known as fluidization, imparts many important advantages to the FBR.
As a result, the fluidized bed reactor is now used in many industrial applications
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1.WHAT IS A BIOREACTOR??
2.FLUIDISED BED BIOREACTOR!!!
3.WORKING PRINCIPLE::
4.FACTORS.
5.ADVANTAGES
6.DISADVANTAGES &
7.APPLICATIONS!!!!
3. A bioreactor may refer to as
any manufactured or engineer
ed device or system that
supports a biologically active
environment.
On the basis of mode of
operation, a bioreactor may
be classified as batch, fed
batch or continuous
4. • A fluidized bed reactor (FBR) is a
type of reactor device that can be used
to carry out a variety
of multiphase chemical reactions.
• In this type of reactor, a fluid (gas or
liquid) is passed through a
solid granular material (usually
a catalyst possibly shaped as tiny
spheres) at high enough velocities to
suspend the solid and cause it to
behave as though it were a fluid.
• This process, known as fluidization,
imparts many important advantages to
the FBR.
• As a result, the fluidized bed reactor is
now used in many industrial
applications
5. • Fluidized bed reactors are the most popular configurations employed from
laboratory to commercial scale.
• Fluidization is a process in which the upward flow of a fluid suspended
particles.
• Fluidization is first used in the 1920s for coal gasification.
6. • The fluidized bed bioreactors are generally operated in co-current flow.
• The particles used in FBBs are of three different types:
i. Inert core on which the biomass is created by cell attachment.
ii. Porous particles in which the biocatalyst is absorbed.
iii. Cell aggregates.
• The solid substrate (the catalytic material upon which chemical species react)
material in the fluidized bed reactor is typically supported by a porous plate,
known as a distributor.
• The fluid is then forced through the distributor up through the solid material.
7. • As the fluid velocity is increased, the reactor will reach a stage where
the force of the fluid on the solids is enough to balance the weight of
the solid material. This stage is known as incipient fluidization and
occurs at this minimum fluidization velocity.
• Once this minimum velocity is surpassed, the contents of the reactor
bed begin to expand and swirl around much like an agitated tank or
boiling pot of water. The reactor is now a fluidized bed.
• A bed of immobilized enzymes is fluidized by rapid upward flow of
the substrate or in combination with a liquid or secondary fluid
stream.
• Depending on the operating conditions and properties of solid phase
various flow regimes can be observed in this reactor.
9. Uniform Particle Mixing: Due to the intrinsic fluid-like behavior of the solid
material, fluidized beds do not experience poor mixing as in packed beds. This
complete mixing allows for a uniform product that can often be hard to achieve in
other reactor designs. The elimination of radial and axial
concentration gradients also allows for better fluid-solid contact, which is essential
for reaction efficiency and quality.
Advantages
Uniform Temperature Gradients: Many chemical reactions require the addition
or removal of heat. Local hot or cold spots within the reaction bed, often a
problem in packed beds, are avoided in a fluidized situation such as an FBR. In
other reactor types, these local temperature differences, especially hotspots, can
result in product degradation. Thus FBRs are well suited to exothermic reactions.
Researchers have also learned that the bed-to-surface heat transfer coefficients for
FBRs are high.
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10. Ability to Operate Reactor in Continuous State: The fluidized bed
nature of these reactors allows for the ability to continuously withdraw
product and introduce new reactants into the reaction vessel. Operating at
a continuous process state allows manufacturers to produce their various
products more efficiently due to the removal of startup conditions in batch
processes.
CONTINUED…
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USEFUL IF THE REACTION INVOLVES THE UTILISATION OR
RELEASE OF GASEOUS MATERIAL.
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11. DISADVANTAGES
Increased Reactor Vessel Size: Because of the expansion of the bed
materials in the reactor, a larger vessel is often required than that for a packed
bed reactor. This larger vessel means that more must be spent on initial
capital costs.
Pumping Requirements and Pressure Drop: The requirement for
the fluid to suspend the solid material necessitates that a higher fluid
velocity is attained in the reactor. In order to achieve this, more
pumping power and thus higher energy costs are needed. In addition,
the pressure drop associated with deep beds also requires additional
pumping power.
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12. Particle Entrainment: The high gas velocities present in this style of
reactor often result in fine particles becoming entrained in the fluid.
These captured particles are then carried out of the reactor with the fluid,
where they must be separated. This can be a very difficult and expensive
problem to address depending on the design and function of the reactor.
This may often continue to be a problem even with other entrainment
reducing technologies.
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CONTINUED…
DIFFICULTY IN SCALLING-UP THESE REACTIONS.
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13. APPLICATIONS OF FLUIDIZED BED
BIOREACTOR
IN WASTE WATER TREATMENT:
• The use of fluidized bed reactor in wastewater treatment, represents a
unique opportunity for cost-effective treatment of wastewater containing
recalcitrant pollutants (compounds that are slowly biodegradable or non-
biodegradable are known as recalcitrant compounds, and range from
simple halogenated hydrocarbons to complex polymers)
• Although the application of fluidized bed reactor in biological wastewater
treatment is well established with many large-scale plants in existence, its
application in advanced oxidation processes is mostly at laboratory-scale.
14. A major application of FBBs is fluidized catalytic cracking which was
developed in 1940s.
Anaerobic fluidized-bed platform has been tested as an anaerobic
platform for the high strength and high solids waste streams such
as the municipal sludge's and corn ethanol thin stillage.
15. REFERENCES:
•IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book") (1997). Online corrected version: (2006–) "bioreactor".
•Reference : Howard, J. R. (1989). Fluidized Bed Technology: Principles
and Applications. New York, NY: Adam Higler.
Reference : Applications of fluidized bed reactors in wastewater treatment – A
review of the major design and operational parameters
https://www.sciencedirect.com/science/article/pii/S0959652616314901
