Euroflo Dredging Pumps at London Array.
VBMS is an engineering consultancy company based in the Netherlands that engages in many sustainable energy projects. It specialises in the installation of (onshore & offshore) grid-to-grid power cable connections for the renewable energy sector. Euroflo was contacted by VBMS because they had encountered a significant problem when trying to connect a supply cable to the base of a number of turbines on the London Array, which is situated in the outer Thames Estuary.
The project’s aim was firstly, to remove a build-up of seabed sand and sediment that had blocked the cable’s termination point and secondly, to finish connecting the wind turbine’s mains cable to the landfall sub-station. Euroflo was asked to supply dredging pumps, which had to be capable of operating at up to 20 metres in depth, depending on tidal conditions. VBMS required a heavy-duty dredging pump that could withstand the effects of seawater corrosion and could pump up to 100 tonnes of sand per hour. Euroflo supplied the DP50 D and EL 60HD Dredging Pumps. The former was to be used for duty and the latter for standby. Both were fitted with 30m of screened safety cable and were operated via an electronic soft- start control panel, which was mounted on the deck of the barge. Power was provided by a Euroflo 250kVA generator.
The pumps were tasked with moving the mixture of sand, silt and seawater away from the immediate vicinity through 50m of a 200mm diameter pipe (supplied by Euroflo), to an open discharge located further along the seabed. The specific gravity of the mixture was around 1.3 -1.5 kg/m3 and contained solids up to 50mm in diameter. The agitators fitted to the Euroflo Dredging Pumps were able to ensure that the sand and silt was efficiently mixed with the seawater prior to discharge. This ensured that the operation (to clear the blocked area) was carried out as effectively as possible.
A key part of the success of this operation was to maintain the velocity of the mixture through the discharge pipe at above 3m/s, in order to prevent settlement.
Both of the Euroflo Dredging Pumps performed their job to a high standard and showed no signs of wear, despite the dredging pump’s exposure to such an abrasive mixture. This can be attributed to two key elements in Euroflo’s approach to the task. Firstly, we selected slow running 6 pole, 960rpm motors to reduce abrasion which is typical in these conditions. Secondly, we selected a tough high chrome content (28%) wet end to withstand the incredible wear challenges on the material.
Euroflo were able to offer a turn-key solution for VBMS; delivering all the equipment required by truck to the quayside for loading on the barge, and also providing a technician to assist with the set-up of the equipment.