Self-priming Magnetic Drive Rotary Vane Pump for Discharging Bilge Water from Subsea Turbine

Enquiry for a Pump to Discharge Bilge Water with Trace Amounts of Oil

The World is becoming more conscious of how our electricity is produced and more companies are investing in renewable energy to combat global warming. A limitless supply of power is waiting in the oceans, expecting to be harnessed for a clean power source. Tidal energy has become one of the main sources of renewable power and this is growing.

Tidal energy is achieved by lowering a subsea turbine into the ocean to turn kinetic energy from water currents into mechanical power. Similar to a wind turbine, the flow of water rotates the propeller and thus energy is produced naturally.

We were contacted by a manufacturer of these systems; they were having difficulty with their current pumps that were being used to discharge a bilge mixture of sea water and trace amounts of oil that leak inside the turbines during operation. While the turbine is submersed in the sea water, some fluid can leak inside and become mixed with trace amounts of oil forming a bilge. This bilge falls into a holding tank and needs to be discharged once a day when it becomes full.

The holding tank is small and only a low flow rate of around 250 litres per hour is required to empty it in 15 minutes. Due to the sensitivity of the system and location of the pump, it must be self-priming, reliable and simple to maintain, produce minimal pulsations and produce high pressures of up to 10 bar to ensure the bilge is discharged effectively.

North Ridge's Selection of our Self-Priming Positive Displacement NRHTP300 Magnetic Drive Vane Pump in Stainless Steel 316

After discussions with the customer and reviewing their design, we were able to specify the ideal solution. Our NRHTP300 magnetic drive vane pump fulfils all the requirements, it is self-priming and able to perform suction lifts up to 4 metres vertically. This model produces a very low flow rate of 250 litres per hour while also being able to produce pressures up to 11 bar. We had the pump manufactured in stainless steel 316 for compatibility with the sea water and oil, providing long life and reducing maintenance.

Due to the positive displacement design, a constant flow rate is achieved while allowing for fluctuations in system pressure. The rotary pumping action is smooth and therefore no pulsations are generated, protecting the customer’s sensitive system design. Another huge benefit of our NRHTP vane pump range is that it is seal-less, the magnetic drive replaces a standard mechanical seal, meaning that there is no risk of seal failure and therefore no fluid leaks. This makes maintenance simple and low cost while also providing reliability and peace of mind.

Below is specification of the rotary vane pump supplied: