A project which expanded significantly in scope – and an appreciative client

Greve Solrød Forsyning is preparing to face future heavy rainfall using advanced control and rain management systems and three Grundfos SE1.160.300 pumps from the new series of large wastewater pumps. But while they are at it ...

The plant dates from 1967 and the pumps were last changed in the early 90s, so Greve Solrød Forsyning decided it was time to upgrade one of the company’s two treatment plants, in Solrød.

The project tender was replacement of the four old pumps, with the requirement that the existing capacity of 1,250 m3/h be increased to 1,700 m3/h. This gave Sales Manager Tom Thomsen at Grundfos the opportunity to bring the new generation of SE pumps into play. The series comprises 9-30 kWh wastewater pumps featuring the highly acclaimed S-tube impeller, making them perfect for the job in Solrød. “We calculated that three 16 kW models with DIN 300 flanges and three frequency converters with Profibus could provide the 1,700 m3/h required. This meant they could keep one of the old pumps as a reserve,” explains Tom Thomsen.

This solution appealed to Ole Schlander, Project Engineer at Krüger and consultant for Greve Solrød  “When I look at pump curves and power, it is clear that these are excellent pumps,”says the engineer.

New pumps, pipes, valves and crane sytem

However, Tom Thomsen knew from experience that new pumps of this size in an old installation could represent a challenge. “One of the things I was interested in was the pipe work,” explains Grundfos Sales Engineer Klaus Gerhard Porsmose. “The flanges on the new pumps have different dimensions, and we know that old cast-iron pipes can look good on the outside, but be a different story inside. I found this to be the case in Solrød, where I could hear a stone turning over in the pipes but unable to get out – inhibiting the speed of the media.”

So the Grundfos sales engineer proposed completely new pipework, from the inlet to the outlet, and new valves as well. The building’s old crane system also came under scrutiny. “The crane tracks were out of alignment with the pumps, making it difficult whenever the pumps had to be lifted out for inspection. The crooked lifts were time consuming and resulted in a poor working environment. We proposed the installation of a new travelling crane, so the pumps (each weighing 500 kg) can be hoisted straight up in the future. This means it will probably take only an hour to carry out an inspection, and with a much better working environment.”

Planning down to the smallest detail

Ole Schlander makes it clear he is very happy with Grundfos’ input and effort. What was intended as a simple pump delivery ended up becoming a package solution. The practical elements of the project – purchasing, installation and inspection– were also assigned to Klaus Gerhard Porsmose. He put together a team of experienced internal and external technicians who will get the new pumping system operational over three long working days.

Prior to decommissioning the old pumps and pipework the plant has been thoroughly cleaned and the new crane system installed in the roof, so it can be of assistance. “Perhaps we will get the first pump operational on day one,” says the Grundfos sales engineer hopefully.

Want to know more about this wastewater treatment project? - Download the full version of the case story in pdf here