Cavity Pumps Provide the Solution at Sewage Works

Three revolutionary maintain-in-place EZstripTM progressing cavity (PC) pumps from NOV® Mono® (UK) have been installed at Dŵr Cymru Welsh Water’s sewage treatment works (STW) in Ruthin, Wales to improve process efficiency by reducing maintenance downtime at the site.

Commissioned by Imtech Process Ltd, one of the NOV Mono EZstripTM pumps has been installed as a thickened sludge transfer pump to transfer sewage sludge from the on-site thickener process to consolidation tanks, where the thickened sludge is then combined with imported sludges. The sludges are then macerated by inline Mono Munchers prior to being fed into the digester by the other two NOV Mono EZstripTM pumps in a duty/standby configuration.

David Kelly, Project Engineer with Imtech Process Ltd., commented: “We were experiencing problems with the existing pumps which would regularly block up and therefore require a complete overhaul every six months. Due to the restricted space, maintenance of the existing pumps was proving difficult and removal of the rotor and stator in situ was practically impossible.

To provide a solution, three Mono EZstripTM pumps were installed onto the duty. The NOV Mono EZstripTM pump design allowed quick and easy in-situ inspection or replacement of the rotor and stator and resulted in a reduction in both maintenance cost and downtime.”

Pamela Moore, who worked on the project as Imtech’s Mechanical Design Engineer, added “The new pumps have provided us with a robust and reliable solution, and we are very happy with their performance. The NOV Mono sales and engineering departments have also been very supportive and willing to offer help and advice whenever required.”

NOV’s Mono EZstripTM progressing cavity pump is the biggest leap forward in PC pump design for 30 years and is an extension of Mono’s popular Compact C Range. The EZstripTM has been specifically designed to provide a quick and easy way to disassemble, de-rag and maintain a PC pump in-situ without the need to dismantle any pipe work from the pump, minimising the costly maintenance and down time that servicing can often cause.

The chamber of the EZstripTM pump has a two piece design which can typically be opened in less than one minute, the suction chamber and rotating parts de-ragged and the chamber reassembled with a spanner and an Allen key. The whole operation can take less than two and a half minutes (depending on the severity of the rag blockage).

The EZstrip™ pump can be installed into new plants or retrofitted into existing NOV Mono

Compact C installations. No electrical disconnection is required and suction and discharge pipes remain untouched. The model range has a capacity of up to 165m3/h and 12 bar pressure, and is available in either cast iron or stainless steel. A choice of rotor and stator materials are available, including WRAS compliant elastomers and a pre-assembled drive train, with two year warranty.