Euroby is excited to announce the arrival of Xelletor – Flottweg SE’s latest centrifuge technology.

A radically new design addresses the three “holy grails” of dewatering – cake dryness, low energy consumption and low polymer consumption – improving all three.

Flottweg have re-examined how the decanter functions and how dewatering is conventionally optimised according to the nature of the feedstock. Granular sludges usually require a shallow cone angle of about 8°. This geometry creates a large discharge diameter and hence a shallow pond; the solids usually settle quickly and the shallow cone angle facilitates discharge. In the case of fine, pasty sludges like sewage sludge, settling is slower and the dewatering is effected by a compressive action.

A steeper cone of 15° and a smaller discharge diameter is utilised to form a deep pond, this allows a longer settling time – or greater bowl capacity, and the additional head of water increases the compressive force on the sludge. The limiting factor here is the scroll body which hinders the development of an ideal “super-deep pond” machine.

Flottweg have looked at modern engineering construction techniques and, taking a leaf out of the motorsport book, replaced the scroll body with an open space-frame on which the flights are mounted.

The design results in an extremely deep pond – with perfect axial flow. Whereas previously the feed stream was introduced in to the pond radially, with a great deal of turbulence – and associated energy losses, the Xelletor feed stream is axial and meets the liquid surface with a minimum of disruption resulting in smooth feed acceleration and low vibration.

The use of a “negative dip weir” permits the use of a large discharge diameter for the cake, but a small diameter for the centrate. The centrate discharges at a small radius and less energy is lost at the discharge point, also, the greater depth behind the dip weir serves to assist cake transfer past the dip weir by hydraulic pressure, with more energy savings.

So – what does this mean for the operator?

Tests at the end of 2015 against “conventional” Flottweg decanters showed the following improvements:

  •  2 % higher cake dryness, or…
  • 2 kg/tD.S. lower polymer demand
  • 40 % saving in power consumption (compared to a traditional decanter, in this case a Z4E)
  • Smooth operation – low vibration
  • No more wear in the feed chamber, because there is no feed chamber
  • Variable feeding point, adjusted by varying the length of the feed pipe

10% less sludge for disposal – Save space and disposal costs!

The use of super-deep pond technology means you get up to 2 percent higher dry substance (DS) content. The dryer the sludge, the less the sludge volume, and thus the greater the combustion value. Up to 2 percent more DS reduces sludge volume by up to 10 percent.

20% less energy required – Act sustainably!

By operating Xelletor decanter centrifuges, you’ll save another 20 percent in energy compared to conventional sewage sludge centrifuges.

20% less flocculant in use – Lower your purchase costs!

Flocculants/polymers are frequently used in sludge dewatering to bind sludge particles together. This makes the particles larger, simplifying and improving sedimentation.

With the new Xelletor decanter series, you’ll save up to 20 percent of polymers with the same discharge quality.

Maintenance-optimized Design – Reduce your service and maintenance costs!

The scroll and rotor of Xelletor centrifuges can be installed and removed quickly. Wear parts can be replaced or serviced simply and directly on-site. If larger repair or service work is required, our competent Service Team is there for you anywhere in the world. We are available to answer your questions 24/7.