Product category:
Motors and Variable speed drives
News Release from: Emotron | Subject: Noxon centrifuges
Edited by the Processingtalk Editorial
Team on 14 May 2008
Energy-efficient centrifuges for water
plant
When the Falkenberg treatment plant in southern Sweden invested in new Noxon decanter centrifuges for sludge dewatering, they specified Emotron variable speed drives
This was one of the first times that the decanter manufacturer Noxon had used the Emotron VFX in its product offering, with the energy generated by the braking motor being re-used by the driving motor More new projects are now being planned
This article was originally published on Processingtalk on 8 Jun 2006 at 8.00am (UK)
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The Falkenberg Municipality in Sweden has been using Emotron products as standard for several years now to protect and control the operation of its electric motors in treatment plants, water purification plants and pumping stations.
Operational electrician Tomas Bjurklint sees major benefits with the Emotron shaft power monitors, soft starters and variable speed drives.
"We value the user-friendliness above all.
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That is essential in order to minimise downtime".
New decanter centrifuges for dewatering sludge.
When Falkenberg treatment plant invested in a new solution for dewatering sludge, they chose two decanter centrifuges from Noxon, a Swedish company with its own development, design and manufacturing resources, serving customers primarily in Europe and Asia.
A decanter centrifuge consists of a drum and a screw conveyor that rotate independently of each other at up to 3600 rpm, depending on machine and sludge type.
The sludge is fed into a mixing chamber where polymer is added so that the sludge flocculates.
Dewatering is achieved through the sludge being flung out through holes against the outer walls of the drum.
The dewatered sludge is transported out by means of the screw conveyor.
When placing their order, the Falkenberg Municipality requested that Emotron variable speed drives be used.
This was a new experience for both parties.
The municipality had previously only used the Emotron FDU for regulation of pressure and flow, but an Emotron VFX was now required, which has been developed for this type of dynamic application.
Noxon had always used a different make as standard for its centrifuges and had never even tested Emotron units.
Because the process uses two electric motors, one driving and one braking, it required an efficient solution without brake resistors.
Two Emotron VFX variable speed drives of 37 kW and 11 kW respectively control the two electric motors that power the drum and brake the screw conveyor so that it maintains a suitable speed.
When braking, so-called generative operation, energy is generated that is normally converted into heat and dissipated via braking resistors.
The Noxon solution re-uses the energy instead.
Thanks to the two variable speed drives being interconnected via a common DC-link, the braking motor energy is fed directly to the driving motor.
The requirement for energy from the mains is reduced and the cost of brake resistors is saved.
The Falkenberg treatment plant was one of the first installations where Emotron variable speed drives were used for such energy-efficient control of the Noxon decanter centrifuges.
The positive experience here has resulted in the solution being implemented for other customers, and more new projects are planned.
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