Look behind the scenes
When pumps are used on ships and in ports, the technology must meet special requirements: this means the pumps should not only cope with a really wide variety of fluids, such as wastewater and lubricant oil, but should also be as space-saving, maintenance-free and easy to handle as possible.
NETZSCH Pumpen & Systeme GmbH has developed three different pump types, which can be universally deployed as transfer and booster pumps on ships and wharves, as well as on offshore platforms – to cover the full range of requirements in the maritime sector, from fuel or sludge transport, through loading and unloading, to stripping. NEMO® progressing cavity pumps, which cope particularly well with highly viscous media thanks to their special conveying principle, are therefore suitable for oil sludge or wastewater. The more compact TORNADO® rotary lobe pumps, which enable a higher flow rate, are for instance used to transfer wastewater, as well as to load and unload various media. The pumps can also be supplemented by macerators for the grinding and separation of larger, harder objects, primarily when conveying wastewater.
Thanks to their special design, NEMO® progressing cavity pumps can also cope with liquid media which contain solids, which means they are frequently used on passenger and container ships to convey wastewater. The pumps are based on a rotor that turns in an oscillating motion within a fixed stator that is geometrically adapted to it. The precise geometrical mating forms conveying chambers during rotation which transport the medium smoothly from the inlet to the discharge side. Because the chambers are self-sealing, this not only prevents backflow, but also ensures that the conveyed medium is transported at stable volume and pressure, so that no shear forces and hardly any pulsation occur. With this displacement technology, the consistency, and especially the viscosity, of the medium are insignificant in terms of the product flow. This is why the NEMO® pumps, which have a capacity of up to 400 m³/h, are not only used for wastewater, but also for pumping media, including oil residues and sludge, on oil tankers and cargo ships and even mixtures of oil, gas and sand on offshore platforms. In the process, the quantity transported is determined solely by the speed and can therefore be continuously and very precisely controlled with a metering accuracy of three to five percent. This enables the quantity required in each case to be metered directly from the supply line or the barrel. The progressing cavity pumps are also suitable for stripping and cleaning oil tanks on wharves.
In addition, a grinder which grinds and separates hard and heavy particles, can also be used for wastewater. It is installed in the wastewater circuit upstream from the pumps and thus prevents clogging or blocking due to solid contents, because it is even capable of chopping up fibre entanglements. The grinder also prevents the blocking of pipelines and further downstream equipment, and is used on passenger ships in particular.
When space is limited, especially on ships, another type of pump, the TORNADO® rotary lobe pump, is ideal for the maritime sector, as it has a particularly compact design, while at the same time ensuring a high flow rate. The displacement element in these pumps consists of two rotary lobes that rotate in opposite directions, thus transporting the media smoothly but continuously. The delivery rate is also independent of the viscosity of the medium with this version. The TORNADO® T2 type pumps in particular are specifically designed for the demands of use on the high seas: they not only take into account the limited space available on board, but also reduce expenditure on spare part stock and maintenance. Instead of a complex and bulky timing gear, the aggregate has an oil-free synchronised gear with belt drive which reduces the weight of the pump by at least 30 percent and ensures a very small installation depth. In addition, the whole mechanism is less susceptible to faults, which means the range of spare parts can be kept very low.
Capacity: NEMO® up to 400 m³/h
TORNADO® up to 1000 m³/h
Media: oil residues and sludge, mixtures of oil,
gas and sand, industrial oil,
multiphase mixtures, drill cuttings and
Grinding: even fibre entanglements
Metering accuracy: 3-5%