Traditional permeate drying technology
methods have inherent problems of low capacity,
high energy costs, high capital investment
in large plants and potentially high environmental
costs. The new Tixotherm(tm) process from Niro,
however, is much more efficient.
The challenge is to create a free-flowing,
non-caking powder from the liquid whey or
permeate. This is difficult because these
dried whey products tend to be hygroscopic
and thermoplastic. They will tend to absorb
water from the surrounding atmosphere and
become sticky, making powder rock solid -
even in sealed bag.
The four-stage Tixothermtm process, however,
converts the liquid whey into a free-flowing,
non-caking powder. The water content of the
whey or permeate is initially decreased in
an Agitated Film Concentrator resulting in
a water content of just 15%. High sheer rates
within the concentrator keep the viscosity
of the product paste low owing to its thixotropic
nature. The product passes to a Mixing Crystallizer
that increases the dry mater content, encourages
further lactose crystalisation and creates
a semi-hard crystallinic paste with a friable
texture, easy to particulate. Final drying
is performed in an Agitated Fluid Bed and
a VIBRO-FLUIDIZER®
at high temperature to inhibit the growth
of micro-organisms. Process air is cleaned
in a SANICIPtm bag filter and the retained
powder returned to the process.
The whole plant is very compact saving
approximately 50% in building size with the
consequential savings in building costs.
Comparisons have shown that the Tixotherm
process consumes only 80% of the energy of
the traditional 'wet process'.
Niro is a member of the GEA Group and the
world leader in spray drying. 
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