Fbd(Fluidized Bed Dryer)

1. Fluidized Bed Dryer
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. What is Fluidization?
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. Fluidization (or fluidization) is a process similar to liquefaction whereby a granular
material is converted from a static solid- like state to a dynamic fluid-like state. This process
occurs when a fluid (liquid or gas) is passed up through the granular material. Different
types of fluidized beds are formed depending upon the velocity of fluid.
. 1)INTRODUCTION
. Fluid bed drying is most widely used technique for drying pharmaceutical powders and
granulation. The direct contact between particles and air/gas is possible in fluid bed system.
Here any type of inert gas or air is used. They can be designed in either batch or
continuous type fluid bed dryer.
. 2)PRINCIPLE
. In fluidized bed dryer, hot air is passed at high pressure through a perforated bottom of the
container containing granules to be dried. The granules are lifted from the bottom and
suspended in the stream of air. This condition is called fluidized state.
. PARAMETERS TO BE CONTROLLED IN FLUIDIZED BED SYSTEMS
. A) Apparatus Parameters
. 1) Air distribution plate Position influences the airflow pattern inside the body.
. 2) Shape of instrument body Annular base gives better product and fluidization
. 3) Nozzle height in case of coater and granulator. It plays vital role as in coating, the
atomized coating solution should not get dried before reaching the tablet surface.
. 4) Positive and negative pressure operation.
. B)Process Parameters The following inlet air parameters are critical
. i) Temperature As the inlet air temperature increases the rate of drying increases and vice
versa. This approach to increase the rate of drying can not be used always because some
materials are harmed by high temperature, e.g. Ibuprofen liquefies above 60°C temperature of
inlet air should be optimized without any impact on product quality. If temperature is high,
it leads to blistering. If temperature is low, soft spot can be formed.
. ii) Humidity Humidity in the inlet air should be as low as possible and ideally
dehumidified air should be used for faster drying rate because as the humidity of inlet air
decreases the rate of drying increases.
. iii) Air Flow Rate Air flow rate should be controlled properly in order to get efficient use
of drying air. Air flow rate should not be too fast or too slow but optimized to have efficient
drying.
. C) Product Parameters: Initial moisture content of material. It should not be high
otherwise it increases drying time. Batch size. It should be small and optimized based on
feasibility.

2. .
. CONSTRUCTION
. The construction of a vertical fluidized bed dryer The dryer is made of stainless steel or
plastic. A detachable bowl is placed at the bottom of the dryer, which is used for charging
and discharging. The bowl has a perforated bottom with a wire mesh support for placing
materials to be dried. A fan is mounted in the upper part for circulating hot air. Fresh air
inlet, pre-filter and heat exchanger are connected serially to heat the air to the required
temperatures. The temperature of hot air and exit are monitored. Bag filters are placed
above the drying bowl for recovery of fines.
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. WORKING
. When the velocity of the air is greater than the settling velocity of granules, the granules
remain partially suspended in the gas stream. After some time, a point of pressure is
reached at which frictional drag in the particles is equal to the force of gravity. The
granules rise in the container because of high velocity gas and fell back in a random boiling
motion. This condition is said to be fluidized state. Drying is achieved at constant rate
and falling rate period is very short.
. Solids Drying T, Time dw/dT Drying Rate A B C D AB - Warming up period BC - Constant
Rate Period ‘C’ - Critical Moisture Content CD - Falling Rate Period
. ADVANTAGES
. It requires less time to complete drying i.e., 20 to 40 minutes compared To 24 hrs of
tray dryer. Handling time is also short. It is 15 times faster than tray dryer. Hot spots are
not observed in the dryer, because of its excellent mixing and drying capacities. It
facilitates the drying of thermo labile substances, since the contact time is short. It can be
used either as batch type or continuous type. The free movement of individual particles
eliminates the risk of soluble material migrating as may occur in static
. TYPES OF FLUID BED DRYER
. A)Batch Type Vertical Fluid Bed Dryer With Granulating Option.

3. . I. Reverse Turning Bed Type In this equipment, by turning the gas dispersion plate (the
reverse turning bed) in 90° direction with the control motor, all the dried material can be
discharged at once.
. II. Rotating Discharge Type Dried material is discharged by opening the discharge gate
equipped at the side of the Dryer. As the perforated plate is used as the gas dispersion plate,
the gas inside the equipment whirls and pushes the dried material out from the discharge gate.
. Characteristics Of Batch Type Fluidized Bed Dryer The residence period of the dried
material can be controlled which results in uniform drying. It is most suitable in case
where an accurate control of the residence period is required at the decreasing rate drying
zone. Small destruction of particle occurs therefore suitable for granular or crystallized
material. Easy operation can be achieved by an automatic control of material feeding,
drying discharging etc. When multiple stage system us adopted, the exhaust gas heat can be
used efficiently.
. B) Continuous Type Horizontal Vibrating Conveyor Fluid Bed Dryer Residence time
in any drying zone is dependent on
. (1) Length of the zone
. (2) The kfrequency and the amplitude of the vibration
. (3) Use of dams Heat transfer units such as tube or plate, are built inside the equipment.
These unit supplies 60-80 % heat necessary for drying.
. Characteristics Of Continuous Fluidized Bed Dryer The materials with relative high
moisture content can also be dried. At and after a second drying chamber, piston flow
ability can be achieved by arranging numbers of the partition plates as per the required
residence period. The perforated plate at the fixed direction ensures easy discharging.
Small destruction of particles, so suitable for granules or crystalline materials. In multiple
zones fluid bed dryers, heating and cooling occurs in same unit. Each zone has
independent control for temperature, dewpoint and velocity of air/gas. By adjusting the
weir height for each zone, residence time can vary up to four fold in the unit.
. Troubleshooting Problem Cause Solution Material Degrades High Drying Time
Reduced particle Size High moisture Contents in dried Solids Material not Fluidizing
Surface Shrinkage Very High Temperature Material contains high moisture contents
High residence time Due to internal diffusion of particles Powders develop electrostatic
charge High temperature Low down the temperature or distribute the
. particles Prefer using twice drying Reduce resistance time Reduce residence time
Use efficient electrical earthing of Drying chamber Optimize temperature
. Applications Instant Tea/Coffee Milk Powder Ceram Slurry Magnesium Chloride
Molasses Poly Aluminium Chloride Enzymes Catalysts Calcium Chloride
Pastes Zeolites Resins Fruit Juice Powder Polyvinyl Acetate Dyes Detergent
Powder Herbal Products Polymers (PVC, PP)
. VALIDATION “
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. Establishing documented evidence that provides a high degree of assurance that a specific
process will consistently produce a product meeting its predetermined specifications and
quality attributes.” Validation applies to processes or analytical methods. Validation
provides an approach to prove quality, functionality and performance of a
pharmaceutical/biotechnological manufacturing process. This approach can be applied to
individual pieces of equipment as well as the manufacturing process as a whole 11 12

4. . Equipment Validation protocol Equipment Validation
. Installation Qualification (IQ)
. Operational Qualification (OQ)
. Performance Qualification (PQ)
. Design Qualification (DQ)
. DESIGN QUALIFICATION Documented verification that the proposed design of
equipment/systems is suitable for the intended purpose. Requirements are best created
before “shopping” is undertaken. Requirements are created by the needs of the
system/process of which the equipment/system will be a part.
. INSTALLATION QUALIFICATION
. “Assurance that the intended equipment is received as designed and specified”.
Verifying proper installation of utilities; water, steam, electrical, compressed air, ventilation,
etc. Instruments for measuring temperature, humidity, time, air volume , pressure as well
as recording devices for these variables should be calibrated.
. Installation Qualification for fluidized bed dryer include the following steps: Verifying
the approved purchase order. Verify model number, serial number. Ensure that all
relevant documentation is received: User manual, Maintenance manual, List of change parts,
Electrical drawings.
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. Check the manufacturer and supplier. Check for any physical damage. Confirm
location and installation requirements per recommendation of manufacturer. Verify that the
utilities required are available. Dust free area and moisture free air should be provided.
Installation shall be conducted per instructions provided in the manual.
. OPERATIONAL QUALIFICATION
. The documented evidence that the system or equipment performs as intended throughout
all anticipated operating ranges. “Confirmation that the equipment functions as specified
and operates correctly”. Verifies correct operation of critical components and operating
ranges as defined by the specification and required performance.
. Verify alarm control. Operate the equipment at low, medium, and high speed per
operations manual to verify the operating control. Verify that all switches and push buttons
are functioning properly. Establish procedures for operation, maintenance, and calibration.
Establish training program for relevant staff. All the electrical fittings in the room must
conform to ISI specifications of Flameproof Electrical fittings. Do the tests for uniform
distribution of air.
. Run three batches of each product and analyze for: Active ingredients homogeneity.
Moisture content. Particle size distribution. Percentage fines. Based on this data we can
fix drying end points for each process.
. Specially for FBD: i. Air temperature distribution: Using thermocouples. ii. Inlet air
installation:
. a) Delay time for achieving constant air conditions: Using thermocouple and hygrometer
. . b) Microbiological quality of the inlet air: Using centrifugal air sampler.
. PERFORMANCE QUALIFICATION
. The documented evidence that the system, equipment or process is capable of consistently
producing a safe product of high quality. Tests to demonstrate that the equipment/system
performs in an actual as-used scenario. Heat Distribution Studies Heat Penetration
Studies
. It is check up of what we want actually for that particular process from the equipment.
. i. Inlet air speed.
. ii. Quality of air.
. iii. Uniform distribution of air.

5. . iv. Mixing of air with temperature. Run the trial batch during operation and there should not
be any change in the: 1. Size, 2. Shape , 3.Surface characteristics of the material which we
kept for drying.
. Conclusion
. Validation provides an approach to prove quality, functionality and performance of a
pharmaceutical/biotechnological manufacturing process. Each time before use of the
equipment it should be calibrated and maintained and proper precautions should be taken to
increase the life span of the equipment.
THANK YOU
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