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99%
accuracy
Dosing acid in the milkstream
Dirk Mucha, seepex
Glanbia Plc in Ireland encountered severe problems with their existing
delivery system, due to inaccurate material dosing. They turned to
progressive cavity pumps, specially adapted for dosing acid, as an
alternative to their existing pump. The present accuracy is as high as
99%, states the company.
Glanbia Plc is one of the largest milk processors in Ireland,
manufacturing a range of dairy products from liquid milk to cheese. The
manufacturing plant in Ballyragget produces a range of powdered milk
products, including casein. The production process for casein involves
dosing the liquid milk stream with a precisely controlled amount of
dilute hydrochloric acid. Because of problems with their existing
delivery systems Glanbia asked seepex to propose a solution.
Based on previous experiences with similar dairy production
environments, seepex proposed that its BN series pump be specially
adapted for dosing acid. As a result, all the internal metal parts such
as the rotor, the coupling rod and mechanical seal casings were
manufactured out of Hastalloy HC4, and the pump casing parts of special,
Halar-coated cast iron. As to the elastomeric parts, these were
manufactured out of EPDM, a elastomer proven to resist many aggressive
liquids. The pump has now been installed close to the storage tanks and
pumps the acid to a nozzle located in the milk pipework where it is
injected into the milk stream.
99% accuracy
“We`re really delighted with these progressive cavity pumps” says John
Moran of Glanbia “The dosing works to more than 99% accuracy and,
compared with the more traditional type of metering pump - diaphragm,
piston or peristaltic, this pump is virtually pulsation free, which is
important to us.” Of equal importance was the fact that the seepex
solution also required no expensive pulsation dampeners.
Frequency inverter
In this installation at Ballyragget the pump speed is varied by a
frequency inverter and a probe in the milk stream measures the pH. This
probe in turn sends a signal to the PLC, which in turn alerts the
inverter controlling the speed and flow rate of the pump. Changes in the
pH of the milk stream result in a corresponding change in pump speed, so
providing a control loop that maintains a completely constant pH within
the milk stream. “Our pump runs for 24 hours a day during our main
production season, right through from February to October, and it has
never given us any problems” says John. “We are so pleased with it - and
the cost savings - that we have just ordered a second pump from seepex.”
Progressive cavity pumps are used in almost all industries for
transporting and dosing thin or high viscosity products with or without
solids as well as aggressive, shear sensitive and abrasive liquids. The
first seepex progressive cavity pump was manufactured in 1972. The
modular design consists of 7 groups and 27 ranges with flow rates from
0.1 l/h to 500 m³/h and pressures up to 48 bar. It can be combined with
a large number of different materials to offer optimal technical and
economic solutions with lowest life cycle costs for almost any
application. <<
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