IDM | Technology/IT
Froneri Schöller uses Fristam
FDS double-screw pumps to
dose its ice cream ingredients
Hygienic, versatile and powerful double-screw pumps
The industrial production of ice cream consists of two phases: it starts
with the preparation of raw materials to create a premix and is followed
by the finishing process where different flavorings are added.
Froneri Schöller in Uelzen, Germany, invested in four Fristam doublescrew
pumps for dosing the various ingredients to the premix. Under demanding
ambient conditions, the FDS 3 pumps (fitted with frequency converters)
can transfer products as thin as 1cP at 25 bar and thick products
up to 1,000,000cP from 1000-litre tanks to the premix vessels. The FDS
pumps can therefore switch between pumping thick product to acting as
CIP return pumps within seconds. This not only simplifies the process, but
reduces costs as there is no need for additional pumps, bypass lines and instruments
for CIP cycles. In a factory that produces around 250 different
types of ice cream and where batch changes often occur several times a
day, this is of course a major advantage.
Creating the premix:
Pumps used in ice cream production must be able to transfer many different
flavorings to the premix. Before lemon juice, kirschwasser, raspberry
pulp, strawberry pieces or nuts can be added, the premix is prepared. At
Froneri Schöller, skimmed milk, dairy cream, quark, yogurt, sour cream
and sugar are mixed, homogenized and pasteurized at exactly 81°C. This
42 · 8 2017 | international-dairy.com
mixture is then transferred to
storage tanks where it sets for at
least six hours. The premix is then
cooled in the freezer to a temperature
between –5 and –10°C and
rotating blades prevent the product
from getting stuck to the inside wall of the cooled drum, while air is added
to the mixture to make it light and creamy.
Delivering the ingredients with the FDS:
The factory in Uelzen is equipped with four delivery stations including load
cells for the various flavoring ingredients. At these stations, the 1000-litre
stainless steel tanks and IBCs in which the ice cream ingredients including
fruit juices, fruit pulp, nuts and egg-sugar mixtures are delivered to the
factory and are connected to the production system. The FDS is designed
to transport shear sensitive ingredients such as whole cooked strawberries
without crushing them, as well as also pumping very "bitty" product
such as nuts and seeds. The smooth axial movement through the pump
means these products cannot get caught between the screws, so there’s
no chance of causing any damage to the product or the pump itself.
The process requires a constant flow rate of 8 m3/h at a differential
pressure of 8 bar. When switching tank at the delivery station, air enters
the pipeline system, which must be eliminated during the initial pumping
phase. At the pressure side, the pipeline features a non-return valve that
must be pushed open by the pump. Due to the excellent suction power of
the Fristam FDS, there is no need for an automatic, pressure-side bleeding
system, which is a known source of contamination. The ability of the
Fristam pumps to transfer media of various viscosities is not only a huge
advantage for production, but also for cleaning. At the Froneri Schöller
plant, there are no bypass lines or CIP fittings, as the FDS pumps also serve
as CIP return pumps, which effectively prevent contamination.
Figure 1: Fristam FDS double-screw pumps – sturdy, versatile
and hygienic
Figure 2: Fristam FDS – conveying
screws with various pitches for
maximum flexibility