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SPRAY
DRYERS |
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| KILBURN designs, manufactures & installs Spray Dryers based on product trials taken in the Pilot Plants at its Test Centre. |
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FUNDAMENTALS
OF SPRAY DRYING |
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| The purpose
of spray drying is to produce a powdered or granular product
in one step by drying an - 'atomized' liquid feed (solution,
suspension, or emulsion) in heated air or other gaseous
medium. By atomizing the feed into fine droplets a very
large surface area per unit mass is generated with a very
short path for heat and mass transfer. The heated air
supplies latent heat of evaporation to the droplets and
brings about rapid drying which in turn brings about rapid
cooling of the drying gas. At the same time the particle
temperature is kept low by adiabatic Cooling. Drying can
take place in a very short time, typically 5-20 seconds. |
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Spray dried particles are usually
spheroidal, which give the product excellent flow
characteristics. Size of the dried product particle
depends on the size of the droplet from the atomizers.
Different atomizers produce different particle size
distribution and spray patterns. The drying air flow
pattern must be carefully selected for optimum performance.
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Atomization
is fundamental to Spray drying
- nearly all operating and product characteristics are
affected by it. To atomize the feed solution or slurry,
high shear forces are applied by one of the following
methods: |
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Centrifugal- accelerating the liquid off the edge
of a spinning wheel. |
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Pressure Nozzle - Spinning the liquid at high velocity
through a small orifice. |
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Pneumatic Nozzle - Impinging a high velocity air
stream on a slow moving liquid |
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ADVANTAGES
OF SPRAY DRYERS |
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KILBURN
TOWER SPRAY DRYER |
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These versatile tower spray dryers
are used for efficient drying of inorganics, catalysts,
ceramics, powdered metals, pigments, dyes and similar
materials. The maximum air temperature is 530 Degree Celsius when
using a direct-fired gas heater. Evaporation capacity varies
depending on the inlet
/outlet air temperature profile and composition of
the feed. The units employ cocurrent or mixed flow
(counter-current) drying principle in an "open
cycle" concept.
Atomization
is performed by either single -fluid or two-fluid nozzles
located at the top or bottom of the tower. Particle size
obtained ranges upto 170 microns depending on feed composition
and operating parameters. The unit is constructed out
of stainless steel. Product is collected at two points-chamber
bottom & cyclone collector. |
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