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FLASH
DRYERS |
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KILBURN manufactures Flash Dryers in technical Collaboration with M/S NARA MACHINERY COMPANY, JAPAN, the leading manufacturer of Flash Dryers in the world.
This design uses suspended particle drying techniques
where surface moisture of the material is rapidly removed
by dispersing the particulate solids in a heated stream
of gas / air. |
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PRINCIPLE OF OPERATION |
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The very word FLASH means instantaneous or
rapid drying of products. |
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There are five primary factors
which govern the speed of drying. These are : |
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1. MOISTURE
DISPERSION |
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4. PARTICLE
STRUCTURE |
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| This is defined
as the accessibility of the moist surface to the
drying medium (Hot air or gas). This is achieved
in a flash dryer by use of a product disperser
such as mechanical scatterer, double paddle feeder
or cage mill etc. by mixing dried product in the
feed. |
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Materials having
capillaries will be able to evolve moisture to
the surface from internal areas more rapidly resulting
in swift drying action. Dense particles which
have no voids are difficult to dry in a flash
drying system. |
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2. TEMPERATURE
DIFFERENTIAL |
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5. PARTICLE
SIZE |
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In flash drying it is possible
to use high initial temperatures. These are
possible due to short contact time with the
result that the product temperature never
exceeds the wet bulb temperature of the gas
unless all surface moisture is removed.
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Drying is accomplished
by evaporation from the surface of the particle.
Therefore to remove the internal moisture, it
is necessary that the moisture reaches the surface
by diffusion. This transfer will obviously take
place most rapidly with smaller particles. |
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3. AGITATION |
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In Flash Dryer, agitation
or turbulence is accomplished by the use of
high gas velocities. The vapour film is continuously
swept away from moist particles. As a result,
moisture removal is practically instantaneous.
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SALIENT
FEATURES: |
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Ideal
for instantaneous
removal of surface moisture. |
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Minimum
moving parts.
Easy to operate. |
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Ideal
for drying heat sensitive materials wet
bulb temperatures at short residence time. |
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High
Thermal efficiency.
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Ideal
for large through-puts. |
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Consistent
product quality with
uniform moisture content. |
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Ideal
for drying cakes, pastes,
abrasives, and sticky materials |
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High Heat
Transfer coefficient |
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Ideal
for both indoor and outdoor installation. |
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Multifunctional
system performing
drying, transportation and classifying
of material in a simultaneous operation. |
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Ideal
for use in combination with other
drying systems particularly fluid bed or
rotary dryers. |
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Low
capital equipment cost. |
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Quick
plant start-up and adjustment
of operating conditions |
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TYPICAL
ARRANGEMENTS |
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arrangements are possible for individual application to
suit specification. A few arrangements are shown here.
The basic components can be changed on need & application
basis.
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APPLICATIONS |
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| Flash drying
can be considered in almost any application where a Filter
Cake, Centrifuge Cake, Sludge or Damp solids can be converted
to a dry powder. |
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This technique
can be economically utilized on practically any material
ranging from heat sensitive Pharmaceuticals like sulfa
drugs, Penicillin, Food Materials like Cocoa Cake, Starch,
Chemicals like Cellulose, PVC, Metallic Stearates, Minerals
and Ceramics like Calcium Carbonates, Clay, and many other
materials .
This technique is most economical if only surface moisture
is to be removed. |
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