Process advantages
Fluid bed drying represents a very effective type of solid drying
(-> Drying). The whole
surface of each individual particle is available for drying in
the
flight phase. The heat transfer is excellent and the drying time
is ideal. The product is dried gently due to these factors. A
homogeneous
product temperature and a uniform drying of the starting product
are achieved as a result of the continuous and thorough mixing.
This cannot always be guaranteed in the case of contact and radiation
dryers. In these cases, local hotspots are quite possible.
If only a small amount of water is to be evaporated, wet granules
can also be dried directly in the Vertical
Granulator: Single pot process (->
Wet Granulation in the vertical granulator).
Principles of operation
For the drying of granules, agglomerates and pellets, Glatt offers
systems with different capacities according to the process requirements,
starting materials and the desired product parameters:
Continuous
Fluid Bed Systems with throughputs from 20kg
to 5t/h.
Batch Fluid
Bed Systems with batch sizes from 2g to 1.5t/batch.
Batch fluid bed
The moist starting product is fed batch-by-batch into the material
container of the dryer for drying. Here it is mixed vigorously
in
the upwards-pointing heated gas stream and held in suspension.
In doing so, it dries to the required end moisture content with
high
heat and material transition coefficients.
The optimum gas speed depends essentially on the particle size and
density. Heat is fed in via the process air. The temperature of
the air can be varied during the drying process. After drying, the
product can be cooled before the material container is emptied and
the next batch starts.
Principle: Batch fluid bed drying
Continuous fluid bed
The activities that are carried out batch-by-batch in the above
process, i.e. at different times, are carried out in different
places
in the continuous process. Moist starting product is fed in continuously
and moves through the process chamber.
Effective drying is guaranteed by different temperatures of the
incoming air. If the last air chamber is operated with cold air,
the dry product can be cooled before leaving the process chamber.
Principle:
Fluid bed drying in the continuous Glatt fluid bed (GF) |
Principle:
Fluid bed drying in the continuous Glatt fluid bed (GF)
Cooling in the last process chamber |
Reproducible process
No matter which system is used – the process must be reproducible.
Premature drying of the top layers of the granulate must be avoided
at all costs. The effects of the weather on the drying process must
be eliminated. Glatt offers fully-developed process technology and
the facility to test and optimise drying processes in the Glatt
laboratory (->
Process Development).
Solvent drying
For the use of organic solvents, Glatt offers circulating gas systems
with proven safety for fluid bed processes and vacuum systems for
fluid bed systems and vertical granulators.
(-> Solvent Recovery)
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