Whey and permeate from ultra filtration of whey and milk are
considered low-price by-products if processed into a powder or expensive
if disposed off into sewage plants. With the increasing cheese production there
will be more and more whey and/or permeate available. This is why GEA Niro has
developed the TIXOTHERM™ process, which converts this by-product into a
first-class non-caking powder product using minimal energy. Reduced
building volume means lower total investment.
How
does the TIXOTHERM™ process work?
Pre-crystallized whey
and permeate concentrates are very thixotropic, i.e. if the concentrate is not
agitated continuously in the crystallization tank in the traditional
process, it will solidify and the higher total solids in the concentrate,
the more solid becomes the concentrate. This phenomenon is used advantageously
in the TIXOTHERM™ process.
All flowsheet animations are available in the GEA Niro download
area.
The TIXOTHERM™ process is a four-step process, where whey or permeate
is evaporated in a falling film
evaporator to 60 % TS. From the evaporator, the concentrate is pumped to a
vertical agitated film high concentrator. Here, the solids are increased
up to 85% TS. However, the high shear rate in the agitated film keeps the
viscosity relatively low. The combination of high solids and low temperature as
a result of the evaporation initiates the lactose crystallization and many
nuclei are formed.
In the subsequent process (the mixing crystallizer), a phase-conversion
of the product takes place enhanced by the addition of fines particles/recycled
cold product from the subsequent fluid bed drying/cooling. This encourages
a rich lactose crystallization.
At the discharge of the mixing crystallizer, the product is now a
semi-solid mass with a friable texture ideal for the following fluid bed drying
and cooling. In this last step of the process, the remaining moisture is
evaporated in an agitated back-mix fluid bed followed by final drying and
cooling in a plug flow VIBRO-FLUIDIZER™. The drying air for the bag mix and plug flow
fluid bed is exhausted through a SANICIP™ bag filter, from where the collected fines particles
are returned back to the mixing crystallizer.
The result of the TIXOTHERM™ process
The final
powder almost has 100 % of the lactose crystallized, i.e. the total moisture
content is 5 % or more. The powder is non-hygroscopic and
non-caking. Energy consumption is reduced by more than 30 % and building
requirements are reduced by more than 50 %. No crystallization tanks are needed
and no spray drying plant is involved to produce whey or permeate powder.
The capacity of a given TIXOTHERM™ plant is a function of the content of
protein, galactose, and lactic acid in the product. That is why a TIXOTHERM™
plant for whey/permeate from mozzarella cheese has lower capacity than for
instance whey/permeate from Swiss cheese.
The TIXOTHERM™ process is available in four industrial-scale
configurations:
Nomical capacities:
- 1,000 kg/hr final powder – 400,000 litres of whey permeate/day
- 2,500 kg/hr final powder – 1,000,000 litres of whey permeate/day
- 5,000 kg/hr final powder – 2,000,000 litres of whey permeate/day
- 7,500 kg/hr final powder – 3,000,000 litres of whey permeate/day
Safety aspects
All plants designed and supplied by GEA
Niro will enable the end user to obtain approvals put forward by the EU
directive.