This document presents information about fluidization and was prepared by 5 students. It defines fluidization as a process where solids are made to behave like fluids by passing gas or liquid upwards. Fluidization is widely used in industries for operations like transportation, heating, mixing and chemical reactions using catalysts. The document discusses fluidization regimes from fixed beds to entrained beds as gas velocity increases. It also describes Geldart's classification of powders and common applications of fluidization like fluid catalytic cracking in petroleum industry.

1. Prepared by:-
(1)Kakadiya Rajan(140840105016)
(2)Dangariya Milan(140840105005)
(3)Vasoya Parth(140840105059)
(4)Dudhat Mayur(140840105009)
(5)Ghodhani Digjay(140840105010)
A
Presentation on
Open Ended Project
Topic:- Fluidization
Subject:- Fluid Flow Operation

2. Topics
Introduction of fluidizationIntroduction of fluidization
Fluidized bed.Fluidized bed.
Fluidization Regimes.Fluidization Regimes.
Geldart’s powder classificationGeldart’s powder classification
Application of fluidizationApplication of fluidization

3. Definition:-
Fluidization is a process in which solids are caused to behave like a
fluid by blowing gas or liquid upwards through the solid-filled reactor
Fluidization is widely used in commercial operations; the
applications can be roughly divided into two categories, i.e.,
•Physical operations, such as transportation, heating, absorption,
mixing of fine powder, etc. and
•Chemical operations, such as reactions of gases on solid catalysts and
reactions of solids with gases etc.

4. Fluidization in vertical column

5.  In a packed bed of small particles, when a fluid enters at sufficient
velocity from the bottom and passes up through the particles, the
particles are pushed upward and the bed expands and becomes
fluidized.

6. The Graph:(01)Superficial velocity VS Pressure drop
(02)Superficial velocity VS Bed Height

7. Pressure drop across fluidized bed:-
Upward force on the bed =ΔPA
If the height of the bed at this point is and the void fraction is Lε,
we can write
Volume of particles =(1-ε)AL
If the acceleration due to gravity is , the net gravitational force on
the particles (net weight) is Net Weight of the particles =
Balancing the two yields:

8. Significance of Fluidized beds:

9. Fluidized beds layout:

10. Fluidization column in industry:

11. (01) (02) (03) (04) (05) (06)

12.  When the flow of a gas passed through a bed of particles is increased
continually, a few vibrate, but still within the same height as the bed at
rest. This is called a fixed bed. (01)
 With increasing gas velocity, a point is reached where the drag force
imparted by the upward moving gas equals the weight of the particles,
and the voidage of the bed increases slightly: this is the onset of
fluidization and is called minimum fluidization.(02)
 Increasing the gas flow further, the formation of fluidization bubbles
sets in. At this point, a bubbling fluidized bed occurs.(03)

13.  If the ratio of the height to the diameter of the bed is high enough, the size of
bubbles may become almost the same as diameter of the bed. This is called
slugging.(04)
 If the particles are fluidized at a high enough gas flow rate, the velocity
exceeds the terminal velocity of the particles. The upper surface of the bed
disappears and, instead of bubbles, one observes a turbulent motion of solid
clusters and voids of gas of various sizes and shapes. Beds under these
conditions are called turbulent beds.(05)
 With further increases of gas velocity, eventually the fluidized bed becomes
an entrained bed in which we have disperse, dilute or lean phase fluidized
bed, which amounts to pneumatic transport of solids. (06)

15. Class AClass A
•Aeratable
•Characterized by a small Dp and small ρp
•Large bed expansion before bubbling starts
•Gross circulation of powder even if only a
few bubbles are present
•Large gas backmixing in the emulsion phase
•Examples: FCC, milk flour
Class BClass B
•Bubbling
•Umb and Umf are almost identical
•Solids recirculation rates are smaller
•Less gas backmixing in the emulsion phase
•Example: sand

16. Class CClass C
•Cohesive
•Difficult to fluidized, and channeling occurs
•Interparticle forces greatly affect the
fluidization behaviour of these
Powders
•Example: flour, cement
Class DClass D
•Spoutable
•Either very large or very dense particles
•Bubbles coalesce rapidly and flow to large size
Examples: Coffee beans, wheat, lead shot

17.  Extensive use of fluidization started in petroleum industry as
fluid catalytic cracking.
 It is used in catalytic processes.such as synthesis of acrelo
nitrile,solid gas reaction,coal gasification.
 It is also used as rosting ores,drying fine solid,adsorption of
gases.
 Solid is vigorously agitated by fluid passing through bed,this
ensure that there is no temperature gradient to bed.
 FCC convert heavier petroleum fraction into smaller.
 In 1950,it was applied to mineral&metallurgical process such as
drying & rosting.
 In 1970, it was used to produce most useful polyethelene, which
is reduced the cost of it very much.

18.  When a liquid or a gas is passed at very low velocity up through a bed of
solid particle,the partical do not move, and the pressure drop is given by
Ergun equation.
 If the fluid velocity is steadily increased,the pressure drop and the drag on
individual particles increased,the pressure drop and the drag on individual
particles increase,and eventually the particle start to move and become
suspended in the fluid.
 The term fluidization and fluidized bed are used to describe the condition of
fully suspended paricles,since the suspension behave as a dense fluid.
 If the bed is tilted,the top surface remains horizontal and large objects will
either float or sink in the bed depending on their density relative to the
suspension.
 The fluidized solid can be drained from the bed through pipes and valves
just as a liquid can, and this fluidity is one of the use of fluidization for
handling solids.

19.  http://www.rug.nl
 http://nptel.ac.in
 http://www.aiche.org
 http://www.msubbu.in
 www2.msm.ctw.utwente.nl
 wikepedia