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Prilling And Granulation
Prepared by: Mussab jaffar Farhad Rafique Muhammad yousaf farooq bashir Khalid nawaz
1) What are prills and Prillings 2)Why we are studying prillings 3) Prilling Tower…? 4)what are grains and granulation 5)why we study granulation 6) Granulator…? 7) And their Industrial applications
Objectives Of Our Presentation
A prill is small agregate of material, most often a dry sphere formed from melted liquid
Soldification of droplets of molten material free falling againstUpward stream of air in tower is
called Prilling
Introduction
It is more convenient for use , storage and transporting because of their much smaller specific surface area and bulk density
Prills of fertilizers are small , easy to handle , easily absorb in land , light in weight , very small impurities etc
Why we need prills
Why we need prills
The melt must be sprayed into droplets uniform size as required
The sprayed droplets must be fully solidified and cooled in order to avoid bonding of particles with each other and caking on wall
Prilling Towerand itsgeneral consederations
It is cylindrical vertical tower with average hight 75 m , in which urea prilling take place with huge diameter it has two prill sections
One is at top from where molten fertilizer comes and other one at bottom from where prills are collected
Construction of prilling Tower
FFC prilling tower(in our home town)
The molten fertilizer is sent on the top of fertilizer plant with the help of centrifugal pump
With the help of spryer molten fertilizer is droped from the top in the form drops inside the prilling tower
While from the bottom hot air is blown which dries the droplets in the form of solid prills
Working principle
PRILLING TOWER:
PRILLING TOWER:
PRILLING TOWER:
This process is widely used in manufacturing of ammonium nitrate, calcium nitrate and fertilizers of N,K and P
Prilling also used in explosives industry to produce porous prills of amonium nitrate which will absorb oil
Typical prilling tower produce 200 ton/day of fertilizer
Products of prilling tower
In order to produce large size fertilizer prills the hight of prilling should be high and vice versa
Higher the hight of prilling tower more will be the strength of prills
50 m high fertilizer prilling tower produce 2mm size prills while , for explosive particles size of prilling tower is about 10 m to produce small prills
Hight Of Prilling Tower
Inside view of prilling tower
The prill tower is a major source of emission in urea plants. The large volumes of discharged untreated cooling air contain particulate urea dust (1-2kg.t-1) as well as NH3 (0.7-1.0kg.t-1).
Increasing the load on a prilling tower can have negative consequences for the prill quality. Higher moisture contents and higher temperatures cause more dust formation and an increased likelihood of caking problems
Drawbacks
Competition from granules The quality of prills is significant less than
that of granules, the main difference being the lower strength and smaller size of prills.
Research has shown that once a farmer has used granules, he will not choose prills again, unless the price is lower.
Most new urea plants are large scale granulation plants and are located in low feedstock areas; these plants are export driven and compete – or will compete – with your prills.
Prilling tower is backbone of fertilizer or any other chemical industry where the final product is in the form of solid prills
We can’t imagine a fertilizer industry without a prilling tower
The process in prilling tower is continuous , prills moves downward due to gravitational force
Importance Of Prilling TOwer
Granulation may be defined as a size enlargement process which converts fine or coarse
It is the process of collecting particles together by creating bonds between them. Bonds are formed by compression or by using a binding agent
particles into physically stronger and larger agglomerates having good flow property, better
compression characteristics and uniformity. The art and science for process and production of
granules is known as Granulation Technology.
Granulation Technology
Powder To Grains
Before granulation After granulation
Wet graulation
Dry granulation
Types of granulation
Dry granulation involves granule formation without using liquid solution
In dry granulation powder particles may be brought together mechanically by compression into slugs
Products maybe sensitive to heat and temperature
Dry Granulation and its characteristics
The process in which powder form particles combine to form bigger and solid particle by the process of agglorimation with the help of binding agent like water
It is mainly used in pharmacutical industry , in the formation of tablets
Wet Granulation
meritsdemerits
Time consuming
Multiple steps involve
expensive
Reduces dust hazard
Improves flow property
The instrument where the process of granulation take place is called granulator
Granulators are classified on the base of shear
Shear is mechanical force applied by instrument
Granulators may be high shear , low shear or intermediate shear
Granulator
There are four major techniques which are used for wet granulation process
1)high shear mixing granulation
2)fluid bed granulation
3)rotating disk method
4)spray drying
Granulation Techniques
In this type of equipment, the particles are set into movement by an impeller
rotating at a high speed (Approx 50- 100 rpm). Equipment also contains a chopper which
rotates at around 1500 – 4000 rpm [10]. The primary function of chopper is to cut large lumps
into smaller fragments thus increases the binder distribution into the blend.
High shear mixing granulation
Impeller speed : higher the impeller speed generally denser and smaller granules , lower the speed generally more porous and large particles
Chopper speed : there is no effect of chopper speed on granules size but in the case when chopper is large size it act as secondary impeller
Input parameters
Surface tension: lower surface tension binder will be use in large amount to form granules of same size as compared to binder with high surface tension
Viscosity: a binder with higher viscosity will produce smaller and stronger granules
Type of binder
Fluid bed granulator is low shear type granulator
Fluid bed means suspended different particles in air
The term fluidization used which means mixing of solids
Fluid bed granulator
The powder particles are fluidized in a steam of air , but in addition of granulation fluid sprayed from nozzle on bed of powder
Heated and filtered air is blown in order to mix powder
Mechanism
Granulation fluid is pumped from a reservior through a spry nozzle positioned over bed of particle the fluid cause the particles to adhere when droplets and particle collide escape of material from chamber is prevented by exaust filter sufficient liquid is sprayed to produce require size particles
> Spray dryer is the process has been used
to produce microcapsules , food ingredients , flavors and various biotechnological ingredients
>This process differ from others as it isa continues process
Spray dryer
Spray dryer is like a prilling tower but it is used to produce granules
Hot solution is sprayed through atomizer from the top
Hot air blown in counter or co current manner
As water evaporate concentration of solution increase and granules form
Granules are separated by cyclone techniques
Mechanism
Rapid and continues process
Reduce overall cost
No dust formation
Suitable for heat and moisture
Advantages
Granulation mainly used in pharmacutical industry
Granulation time particle size Amount of binder granulation time or size Particle size surface area amount of
binder solution granulation time Hydrofobicity hydrophiicity amount of
binder solution granulation time
Thumb rules for granulation
comparison
prilling granulation
In prilling tower hot molten liquid and air moves counter current manner
It do not involve any binder Its end product is hollow
and size is not uniform More tendency for caking
and breakage Operation is simple It does not involve
agglorimation Less storage life
In granulation powdered particles adhere in form of large particle
It involves use of binder End product is solid and size
is uniform No breakage and less caking
tendency Operation is not simple
screening and cyclone separator used
It involve process of agglorimation
Long storage life
Khalid Nawazcell no:+923007024407institute of chemical engineering and technology Punjab university Lahore Pakistan