Look behind the scenes
A waste water treatment plant in Bavaria relied on the use of a progressing cavity pump to convey thick sludge with a solid content of 8 % to an intermediate tank for disintegration. The pump showed a high level of wear due to the abrasive content of the sludge. “Because the solids ratio is over 8 percent, this unit was subject to a particularly high level of wear,” the water treatment manager at the plant explains. “The special texture of the medium is probably also a factor in this: It contains iron and aluminium salts from the tertiary sludge and also iron from a local industrial plant.” The rotor-stator-pairing therefore had to be serviced approx. every 8,000 operating hours.
For the replacement purchase, it was particularly important to the customer that the new pump would have a significantly higher reliability and longer service life and would be especially easy to service. The customer decided to change the manufacturer and use the service-friendly Full-Service-In-Place® version of a NEMO® progressing cavity pump from NETZSCH, which can be maintained directly on site. The maintenance friendly design features one of the largest inspection covers existing. “The inspection cover is secured with just five screws to the pump housing, and can be removed without any special tools in really short time,” Mikael Tekneyan, development engineer at NETZSCH, explains. The NEMO® pump is additionally equipped with the xLC® adjustment unit which allows amendments of the iFD stator® 2.0 to multiply its service life. ”During field-testings lifetime increased by the factor three to four, depending on the medium.
The new pump has been operating since 2016. By using the xLC® adjustment unit the pump ran for another 16,000 operating hours in addition to the previous service life of around 8,000 operating hours.The pump runs 24 h a day and reaches over 8,000 operating hours per year with an output of 1 - 3 m³/h. Any signs of wear occurring on the rotor and stator so far were compensated successfully with the xLC® unit, without changing any pump parts, i.e. the performance parameters of the pump were re-established every time. An end of the service life or a necessary stator change are not yet in sight. “The components are ideally adapted so that the performance has been at the optimum level since installation,” the treatment plant manager explains.