This document provides an introduction to fluidized bed processing, which involves coating, granulation, and drying of particulate materials. It describes the different types of spray processes in fluidized beds, including top spray, bottom spray, and tangential spray. Bottom spray processing, developed by Dr. Dale Wurster, is commonly used in pharmaceutical applications for coating uniformity. The document outlines the key components of a fluidized bed coater and discusses important process parameters like inlet temperature, spray rate, and batch size that can impact performance. Formulation factors like coating solution strength and batch size are also reviewed. Fluidized bed processing is used to improve drug properties like taste, appearance, and release characteristics.

1. INTRODUCTION TO FLUDISED
BED PROCESSOR
PRESENTED BY,
PRASHANT M. PATIL
Research trainee @ USV ltd.,
Govandi, Mumbai.

2. CONTENTS
 Introduction
 Types of sprays in fluidized bed processer
 Synchronous & Asynchronous process
 Parts of Fluid Bed Coating Machine
 Process Parameters in Fluid Bed Coating
 Formulation Parameters in Fluid Bed Coating
 Application
 Conclusion

3. INTRODUCTION-
 Fluid bed processing involves coating,
granulation, drug layering and drying of
particulate material.
 The most commonly known fluid-bed process for
coating in the pharmaceutical industry is the
bottom-spray (Wurster) process.
 Developed by Dr. Dale Wurster in the late 1950s,
the technique is for providing excellent coating
uniformity and efficiency.

4. PRINCIPLE
 A fluidized bed is a bed of solid particles through
which hot air is passed at high pressure through
air distribution plate/bottom of container.
 The particles are lifted from the bottom and
suspended in air stream. This condition is called
fluidized state.
 With the help of spray nozzles granulating liquid
or coating solution is sprayed to produces
granules or coating of particles respectively and
then dried with hot air.

5. TYPES OF SPRAYS IN
FLUIDIZED BED PROCESSER
Depending on the position/location of the spray
nozzle fluid-bed processes are characterized by,
1. Top spray,
2. Bottom spray and
3. Tangential spray

6. TYPES OF SPRAYS IN
FLUIDIZED BED PROCESSER

7. 1. TOP SPRAY-
 Top-spraying is used process for wet granulation, coating,
drying.
 Spray nozzle is located above the expansion chamber.
 Coating liquid is sprayed down onto a bed of fluidized
particles.
 This design of coater is ideal for coating large quantities of
powders, crystals and pellets.
2. BOTTOM SPRAY-
 The bottom-spray (Wurster) fluid-bed method is very popular
in the pharmaceutical industry for drug layering and for
coating to modify or control drug release.
 The hot air is passed through the fluidized bed, particulate
material are lifted in air stream, solution/suspension sprayed
on fluidized bed for granulation and coating.

8. 3. TANGENTIAL SPRAY-
 The nozzle is introduced at the side of a product
container/expansion chamber.
 During processing, three mechanical forces cause particle
movement, mixing, and granulating-
 First, the spinning of the disk generates a centrifugal force.
 Second, a lifting force is generated by the hot air passes
through the adjustable disk gap.
 Third, gravitational force causes material to fall down onto
the disk.
 These forces provide good mixing and result in granules,
drying, coating with good content uniformity.

9. SYNCHRONISE & ASYNCHROONISE
PROCESS
 Asynchronous:
During shaking of filter bags air flow and spray is
continuous.
 Synchronous:
During shaking of filter bags air flow and spray is
discontinued.

10. Parts of Fluid Bed Coating Machine-
Sr. No. Parts Function
1
Nozzle Droplet size and
Distribution is controlled
2 Air Distribution
Plate
Distribute fluidizing air
between the inner and outer partitions
3 Plenum Chamber/
draft tube
Air enters, Equalise pressure for more
even distribution
4 Cylinder (PG) Particles are actually sucked through the
partition gap
5 Filter bags For continuous fluidization
6 Expansion chamber For recurring flow of the particles

11. Process Parameters in Fluid Bed Coating
Parameter Failure
Mode
Failure Effects
Atomization Low or High
Mass/liquid ratio control droplet size
Blower speed Low or High High airflow causes attrition and
generation of fine
Inlet
Temperature
Low or High
Premature Drying
Spray Rate Low or High Wet quenching, agglomeration
Strength of
coating Sol.
Low or High Blockage of nozzle
Batch Size Low or High Affects Fluidization
Size
Distribution
Low or High Affects flow properties

12. Process Parameters in Fluid Bed
Coating
Inlet temperature-
 Inlet temperature is directly affects to the drying
of particulate material.
 High temp. causes development of static charge.
 An increase in the inlet air temperature caused a
decrease in average granule size.
Atomization-
 Atomization of the coating solution on the
fluidized bed is depends on atomization air
pressure. It is solution to the problem of spraying
solution on fluidized bed.

13. Process Parameters in Fluid Bed
Coating
Blower speed-
 High airflow causes attrition and generation of fines.
 The complete wurster cycle get proper coating and drying.
 Proper bubbling is needed uniform coating and drying.
Partition column or air-distribution plate-
 The partition height and the type of air-distribution plate.
Partition height is determined by the particle size, the
substrate density, and the desired velocity of particles
passing into the coating zone.
 Selection of both the air-distribution plate and the partition
height affects the fluidization of the particles.

14. Air-distribution plate/ Bottom
plate-
Sr.No. Bottom plate Particles size
1 A <500 µ
2 B 250 <<1200 µ
3 C 600 <<1800 µ
4 D > 1500 µ and tablets

15. Process Parameters in Fluid Bed
Coating
Spray Rate/ Pump-
 Spray rate was determined by the drying capacity of the
equipment and area of the air distribution plate.
 Spray rate directly affects droplet size.
 Peristaltic pump is used for constant spray rate.
 If there is excessive wetting, many pellets will form bridges
between them, thus joining together to form large wet
lumps which will lead to the defluidization of the bed, the
phenomenon known as wet quenching.
Relative humidity-
 Increase or decrease in RH causes sticking or formation of
lumps….
 Decrease in RH, development of charge on particles (static
charge)
 Increase in RH causes formation of lumps (sticking)

16. Formulation Parameters in Fluid
Bed Coating
Strength of coating Solution-
 Strength of coating solution plays an important role in
nozzle blockade. Upon increasing the strength of coating
solution, the nozzle of Wurster column get blocked due to
higher viscosity hence it should not be highly concentrated
as well as very much diluted.

17. Formulation Parameters in
Fluid Bed Coating
Batch Size-
 Fluidization is affected by the quantity of batch size.
 At least 50% of the volume external to the partition or the
wurster tube must be occupied by particles to be coated.
 To calculate capacity of FBP, calculate the external total
volume of the partition, to multiply it by the bulk density
of the particles which gives the total capacity in Kg as
described in the equation,
Where r1 and r2 are, respectively, the chamber radius and
partition radius, L is the length of partition, ρpis bulk
density of pellets.

18. APPLICATION-
 FBP is used for improve appearance of drug
product.
 FBP is used for taste masking unpleasant drug
and improve taste by sugar coating.
 It is also used for the enteric and stained release
coating.
 To protect active components from atmospheric
degradation.

19. CONCLUSION-
 Fluid bed processor offer unique opportunity to
develop coated controlled release products. But
various process parameters can alter the
performance of a product and hence should be
examined thoroughly.
 It is important to investigate and understand
these variables to ensure a reproducible
performance of controlled release products.

21. REFERANCE
 FLUIDIZED BED PROCESSING FORMULTIPARTICULATES,
by Vipin Saini, rasayan journal, Vol.2, No.2 (2009) 447-450.
 Saurabh Srivastava, Garima Mishra, Fluid Bed Technology:
Overview and Parameters for Process Selection, International
Journal of Pharmaceutical Sciences and Drug Research 2010; 2(4):
236-246.
 Amit Khandagade, Vinita kale & Ravi sinha, CRITICAL QUALITY
RISK ANALYSIS OF PROCESS PARAMETERS OF FLUID BED
COATING TECHNOLOGY, International Journal of Industrial
Engineering & Technology (IJIET), ISSN 2277-4769, Vol. 3, Issue
4, Oct 2013, 15-24.