Recent advances in agglomeration during
spray drying
The quality requirements of instant food powders
in particular are constantly becoming more strict
because an increasing number of properties must
be optimized simultaneously. The increased control
should ensure a high quality product with the highest
degree of uniformity, fulfilling the requirements
set by customers, organizations and industrial and/or
legislative standards.
This situation is very demanding for powder production
people, powder technologists and others responsible
for product qualit. It requires thorough knowledge
of powder technology and an understanding of all
processes or unit operations taking place simultaneously
in a spray dryer.
Agglomeration during spray drying
Agglomeration is often defined as the dissection
of smaller particles into clusters or agglomerates.
Generally the process of agglomeration involves:
bringing independent particles into contact with
one another
enhancing or controlling interparticle adhesion
stabilizing the created agglomerates in some cases
under the action of external forces
Assuming that the agglomeration occurs as a series
of binary interactions the rate of agglomeration
of i- and j-type particles can be expressed by gij
= Kij Eij ni nj where Kij
is a constant collision frequency rate, Eij
is a collision efficiency factor (probability of
adhesion), and ni and nj
are the respective number concentrations of the
two types of particles (Hogg, 1992).
Kij is primarily determined by
specific fines return design parameters, and Eij
is to a large extent determined by the chemical
composition of the particles and their moisture
content, which affect the adhesion of the particles.
ni and nj represent returned fines particles and
primary spray particles.
The concentration of primary spray particles at
a given location in the vicinity of the atomizing
device is determined by the flow and feed to the
atomizer (plant capacity) and atomization efficiency
(spray particle size distribution).
Read more about agglomeration.
For U.S agglomeration
inquiries, please visit the Niro Inc website: www.niroinc.com
for further information please contact
email
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