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