Maintenance made easy at sludge site

Located between Liverpool and Manchester, the Shell sludge site takes sludge from a wide catchment area for processing at a centralised facility where it is dewatered before being used to generate energy.

The Shell Green centre sludge processing plant uses centrifuges to dewater the sludge, each of which has a feed pump supplied by seepex at the time of the plant’s construction.

These pumps were supplied in line with the original plant specification and were large pumps running at very slow speeds to reduce wear.

As part of a continuous cost savings initiative, United Utilities asked seepex to look at the pump systems feeding the dewatering centrifuges to identify how operating costs could be reduced.

After a full diagnostic check of the system by seepex and UU engineers, seepex proposed a trial with a smaller pump fitted with seepex Smart Conveying Technology (SCT).

SCT is an innovation in progressive cavity pump design that increases uptime and offers a significant reduction of whole life costs.

During the trial, stator life was extended compared to the existing pumps, by adjustment of the retaining segments which hold the two-part stator in place.

The SCT pump ran for 30% longer before the stator was replaced and this, combined with lower stator costs for this design, has generated 70% savings in spares parts costs alone.

In addition to increased operating uptime, maintenance downtime is reduced by 85% as rotors and stators can be changed without dismantling pipework.

The trial was so successful that the original eight centrifuge feed pumps have now been replaced by seepex SCT pumps with projected savings on operating costs in the region of £50,000 per annum.