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Starch and Protein from Potatoes
GEA Mechanical Equipment /GEA Westfalia Separator Group
LiquidstoValue
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A Versatile Tuber
In order to guarantee quality and yield, as well as
a high degree of added value in the process of
recovering potato starch, the overall process must
be designed right down to the smallest detail to meet
the specific needs of the product to be processed.
The water content of potatoes, which are used for
starch extraction for more than 150 years, is notably
high at 75 percent which limits its storability.
Extraction of potato starch thus takes place by
seasonal working.
For the process and machine technology this means
100 percent performance no less from the first day
of the season, 4 hours a day, after a production break of
several months. GEA Westfalia Separator Group
provides the outstanding reliability essential for
success in this sector.
GEA Westfalia Separator Group has been playing an
instrumental part in the advancement of mechanical
separation technology for more than 115 years now.
The basis of the innovative capability of the company
are enormous investments in research and develop-
ment as well as close cooperation with universities,
research institutes and industry. With this approach
GEA Westfalia Separator Group has developed numer-
ous innovative separation processes and brought them
to market by applying first class engineering. Today,
the company can handle a total of 3000 processes.
With this knowledge GEA Westfalia Separator Group
has for example succeeded in developing a process for
making efficient use of fruitwater with the aid of
decanters. This not only makes for additional value
of the overall process in form of more marketable
protein. The fruitwater process also reduces the
consumption of fresh water significantly.
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Before starch can be extracted from a potato, the
starch granules must first be released from the cell
structure. High-performance raspers are used for
this purpose which grate the potatoes quickly and
thoroughly and thus release the starch granules,
fibres and fruitwater.
Water containing SO2 is then mixed with the potato
gratings in order to stabilize the microbiological
conditions in the process and to avoid oxidization.
The soluble constituents of the potato contained in
the fruitwater have to be removed from the overall
process as quickly as possible. Decanters are used
for this purpose; these machines separate the pota-
to fruitwater from the gratings, and thus remove
more than 70 percent of the soluble constituents from
the process.
The clarified fruitwater, which is discharged underpressure from the decanter by means of a centripetal
pump, is conveyed to the protein installation for
further processing. Process water is then added to
the dewatered gratings, and the mixture is passed
through a desanding cyclone in order to remove
sand and other erosive constituents effectively. This
arrangement protects downstream machines against
wear and increases the purity of the end starch.
After desanding, the free starch is extracted in four
stages from the potato gratings with the aid of
centrifugal strainers. This task is performed by
conical and rapidly rotating strainer baskets with a
corresponding strainer perforation and an integrated
washing fac ility. Process water is again used for
intensively washing the starch / fibre mixture. Fibres
and starch are separated from each other via strainers.
The counter-current principle is used in order to
minimize the losses. The fibres pass through the next
strainer stages and are eventually discharged from
the extraction process via the fourth stage for
subsequent pulp dewatering. The starch recovered inevery stage is pumped to the upstream strainer until
it leaves the extraction process via the first strainer
stage. The raw starch milk is then pumped to the
Pure Starch, High Yield, Low Water Consumption
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3-phase technology
Potatoes
Starch
extraction
Disintegration
Fruitwater
separationDesanding
Starch concentration
and washing
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actual starch washing process via a buffer tank. A
rotary brush strainer is installed upstream of the
multistage separator washing line in order to prevent
larger particles from entering the centrifuges, where
they might clog up the nozzles. The washing line itself
consists of 3-phase nozzle type separators in three
stages working in accordance with the counter-
current principle. Fresh water is added to the final
stage only. The separators separate the starch milk
into fractions of starch, fine fibres and water. The
starch is concentrated in the bowl, where it is washed
and continuously discharged via the nozzles. After
the final washing stage, the starch is conveyed via a
buffer tank to the dewatering stage. The fine fibres
as well as part of the fine-grain starch are discharged
under pressure via the middle phase as a defined
volume. They leave the washing facility via the first
stage and are sent to the fine-fibre straining process.
The water phase is likewise discharged under pressureas overflow and used as process water. This installation
makes for minimum fresh water consumption and
energy costs for the entire process. This can only be
achieved by 3-phase nozzle separators. It also
simplifies subsequent processing of the fine fibres
considerably. The washed and concentrated starch
milk is dewatered by means of vacuum rotary filters
before it is conveyed to the starch drying process. The
filtrate water is recycled to the starch washing stage
in the form of process water. The fine fibres from the
middle phase of the separators are initially separated
from the starch milk in a -stage centrifugal straining
unit. They are simultaneously washed and subse-
quently subjected to further intensive washing before
being conveyed to pulp de-watering. Any filtrate water
is again recycled to the previous stage. A decanter is
used for dewatering the fine fibres as well as the pulp
from the extraction strainers. The clarified phase is
returned in the form of process water to the wet starch
process. The dewatered pulp can either be dried or
removed from the process and used for example as
animal feed.
Fine fiber
screening
Pulp
dewatering
Fruitwater to
protein recovery
Pulp
Starch
to dryer
Starch
dewatering
Fresh water
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The potato fruitwater from starch recovery contains
high-quality and thus valuable protein that can be
recovered in subsequent process stages. It can, for
instance, be used in the animal feed industry.
Additional benefit is achieved as a result of the
considerable reduction in the effluent load. The
protein installation is an important criterion for
treating the effluent in view of the downstream
evaporator or for a biological effluent treatment plant.
The quality of fruitwater separation in the upstream
starch recovery process is extremely important for
the benefit of the protein installation. Depending
on the process configuration used, up to 95 percent
of potato fruitwater can be separated in starch
installations from GEA Westfalia Separator Group
and used subsequently for protein recovery. The sepa-
rated fruitwater is conveyed under pressure and in the
absence of oxygen directly to the protein installation;
this arrangement avoids negative phenomena suchas heavy foaming and product oxidization. Effective
acid-heat coagulation ensures precipitation of the
potato protein.
Additional Value From the Potato
Dual benet
Steam
Acid
Fruitwater feed
CIP system
CIP liquid
Protein coagulation
Protein dewatering
Pre-heater
CIP recycle
Caustic
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Two heat exchanger stages heat the fruitwater
initially from 0 to more than 100 C. At the same
time, acid is added to adjust the pH value to the
isoelectric point as well as direct steam. This is essen-
tial in order to ensure optimum precipitation of the
protein. The mixture is then injected with direct
steam before it is allowed to rest.
This is where the actual flocculation process takes
place, and also where the flocculant stabilizes. In
order to make optimum use of energy, the coagulated
fruitwater is now recycled via a counter-current
arrangement to the second preheating stage, where
it is cooled to approx. 85 C. This is followed by highly
efficient dewatering of the protein by high-perform-
ance decanters from GEA Westfalia Separator Group.
The decanter has been specifically designed for this
application so that it achieves maximum dewater-
ing of the coagulate and optimum clarification of
the residual effluent. A scroll conveys the dewatered
potato protein to the drying stage. Because the digest-
ibility and colour of the protein depends very much
on the temperature, duration and type of drying, the
drying process is very gentle (in ring driers). The
dried product with a residual humidity of approx.10 percent is then sent to storage and packaging. The
clarified fruitwater from the decanter is pumped
through the first preheating stage in a counter-current
arrangement. This enables most of the generated
thermal energy to be used for preheating the fruit-
water and eliminates the costs for external energy
input. The remaining fruitwater can be sprinkled on
fields, evaporated in evaporators or treated appropri-
ately in effluent treatment plants.
The main benets at a glance Optimum product quality and maximum yield
due to the use of the latest centrifugal separation
technology, such as high-performance
decanters and -phase nozzle type separators
Consistent and intelligent use of process water
requires extremely low consumption of
fresh water to minimize the effluent load and
the energy costs of the entire process
Compact closed systems and CIP capability of
the entire process line for meeting the latest
hygiene requirements
In-line recovery of potato protein under
pressure by means of heat coagulation for
efficient utilization of protein
Dual benefit from coagulation:
More marketable protein
Less effluent load Depending on the specific requirements, a fully
automatic computer-driven process control
facility can be supplied
Protein drying
Residual fruitwater to evaporator
Protein
powder
to silo
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Fine-Tuning for Maximum Dewatering
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Platzhalter Motive
GEA Westfalia Separator Group supplies decanters
in a wide range of sizes and designs always
customized for the specific processing capacity and
the separating task in hand.
In the process of recovering starch and protein
from potatoes, decanters are used for separating the
fruitwater, dewatering the coagulated protein and
for dewatering the pulp. Sophisticated drive systems
ensure a high dry matter content. Decanters from
GEA Westfalia Separator Group have specially designed
drive systems which allow a very smooth adjustment
of the differential speed to the starch or protein
quantity to be separated. This is the only way in which
maximum dewatering and separating capacities can
be achieved.
Drive systems
GEA Westfalia Separator Group decanters have
specially designed drive systems.
2-gear drive
With this drive, the main drive motor drives the bowl
and the housing of the primary gear. An additional
secondary gear allows part of the power required for
the scroll drive to be provided by the secondary motor.
The current of this motor serves as a measure of
torque-dependent differential speed control. The
drive is electronically monitored and can thus
be restarted. Downtimes due to overloading are
thus ruled out and smooth operation is guaranteed.Decanters with this drive, which is patented in many
countries, are used when high torques are required
for maximum yields at low differential speeds.
Differential gear drive
The differential gear drive is recommended when
automatic control of scroll speed is required in
addition to bowl speed control. This is made possible
by the use of two gears. The secondary motor drives
the central inlet shaft and generates the differential
speed proportionally to its own speed. A second inlet
shaft with no speed is connected to the housing. This
makes differential speed independent of bowl speed.
Differential gear drives are used primarily for the lower
differential speed range.
Westfalia Separatorvaripond
reliable mastery of solids concentration
This control system uses existing capacities so
accurately that maximum results are achieved for
minimal duty. Westfalia Separatorvaripond means
variable pond depth with machine running. Even if
feed concentration varies dramatically, the
system controls the liquid level in the decanter bowl
so accurately that the concentration of the con-
centrated solids can be set to a constant value and
maintained exactly. Westfalia Separatorvaripond
facilitates much lower-energy operation, because
adapting the g-force to feed conditions and the
associated reduction in speed allow electrical
energy to be saved. Wear to the components is reduced
and their service life is increased.
2-gear drive Differential gear drive Westfalia Separator varipond
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Solids
discharge
Pressure
discharge
of clarified
liquid
In addition, the simple and optimum facility for adjust-
ing the pond depth can also be used for increasing
the relative clarifying area; this means that extremely
small particles can be separated during the protein
recovery process itself, and excellent separating effi-
ciencies can be achieved. As the clarified liquid is dis-
charged under pressure, the bowl chamber is hydro-
hermetically sealed.
This arrangement avoids additional oxygen
intake and also particularly avoids foaming which
would result in product losses. GEA Westfalia
Separator Group decanters are also CIP-capable in
line with the requirements applicable for process
management which meets the requirements of the
food industry. The twin frequency converter drive
enables the machine to operate at low bowl speeds
to ensure that chemical cleaning is even more effi-
cient. In addition, the decanters are lined completely
with stainless steel, which means that no corrosion
damage can occur. Automatic circulation of lubricat-
ing oil ensures that the decanters have a long servicelife and high availability; the compact design means
that the decanters do not require much space when
they are installed.
The main benets at a glance Variable drive, torque-dependent differential
speed regulation for constant and extremely
high solids concentration even in conjunction
with fluctuating feed concentrations
Adjusted drive concepts: -phase motor with
frequency converter for regulating the bowl
speed or motor for controlled torque starting
Automatic lubricating oil circulation: long
bearing lives due to cooling lubrication and
filtering
Patented pond depth regulator
Westfalia Separatorvaripond: pond depth
adjustment while the machine is running
Paring disc: hydrohermetic operation and
energy saving due to small diameter
Maximum dewatering combined with
maximum separating efficiency
Material and sealing systems matched to the
specific product
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Wash water
Intelligent Machine Technology
for Efficient Processes
High purity, high concentration
A major advantage of 3-phase nozzle type separators
is their ability to enable the water phase to be used
as process water in the entire process and thus to
enable the overall consumption of fresh water to be
significantly reduced. Upon request, GEA Westfalia
Separator Group can of course also supply nozzle-
type separators in 2-phase design.
Nozzle type separators are primarily used for
recovering potato starch. The concentrated starchmilk is extremely pure. It is continuously ejected
through nozzles at the periphery of the bowl, and
then discharged.
An important aspect is guaranteeing a high and also
constant starch concentration. For this purpose, the
starch mass in the bowl is continuously measured. An
intelligent density regulating facility automatically
compensates for any fluctuation by recycling the
necessary amount of concentrate; this arrangement
means that the separator always discharges a constant
starch concentration. The nozzle type separator with
washing facility is used whenever the process requires
additional washing of the suspension.
As the starch fraction is washed with water directly
before the nozzle discharge, process water of poor
quality is displaced from the concentrate area. This
displacement washing ensures that the starch which
is recovered has a high concentration and is very pure.
The quantity of wash water depends on the through-put capacity of the separator and the required degree
of purity of the starch.
In a 3-phase bowl fine fibres which are separated
from the starch are discharged under pressure by a
centripetal pump as a defined volume together with
a proportion of small granule starch. The water
phase is clarified in the built-in disc stack and is also
discharged from the separator under pressure via the
overflow as process water.
Discharge,
light phase
Product feed
Discharge,
middle phase
Discharge,
solids
concentrate
Wash water
3-phase nozzle separator with
at belt drive
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The -phase separator separates into a heavy starch
suspension and a light clear phase consisting of
process water, fine fibres and small granule starch.
With the direct drive, developed by GEA Westfalia
Separator Group, the power is transmitted to the bowl
directly. Due to the gearless drive there is no trans-
formation of speed anymore. Therewith motor sizes
of up to 600 kW are possible which provide for a tre-
mendous boost of performance. Moreover, no energy
is wasted as the transmission is virtually loss-free.
Another great advantage is that the gearless drives
require a minimum of service and maintenance.
The main benets at a glance
Discharge of the concentrate under pressure
via nozzles, discharge of the other phases via
centripetal pump this permits very efficient
counter-current washing with a small number
of washing stages and minimum consumption
of fresh water
The latest sophisticated drive concepts ensure
maximum performance with minimum
maintenance
Washing of the starch suspension before the
nozzle, resulting in high purity and concentration
of the discharged potato starch
Clarifier bowl with closed feed and discharge of
the product phase to avoid oxygen absorption
The solids concentrate is discharged
continuously from the bowl through special
nozzles which save energy due to their specificdischarge angle
CIP cleaning at operating speed
Short spindle drive for low-vibration running
Speed monitoring
Irrespective of whether small or large
capacities are involved GEA Westfalia
Separator Group provides nozzle-type separators
for all desired processing capacities
Discharge,
light phase
Product feed
Discharge,
solids
concentrate
Wash water
2-phase nozzle separator with direct drive
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The information contained in this brochure merely
serves as a non-binding description of our productsand is without guarantee.
Binding information, in particular relating to capacity
data and suitability for specific applications, can only beprovided within the framework of conc rete inquiries.
Westfalia, Westfalia Separator and varipond areregistered trademarks of GEA Mechanical Equipment GmbH.
Printed on chlorine-free bleached paperwww.kabutz.de
B_RR-10-11-0003 ENPrinted in GermanySubject to modification
Werner-Habig-Str. 1 59302 Oelde (Germany)
Phone +49 2522 77-0 Fax +49 2522 77-1794
www.westfalia-separator.com
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