Water management

Screw conveyors for water

Water screw conveyors for clear water
‘A reliable power transmission is crucial’

In water purification plants water is often conveyed with screw conveyors if a certain difference in height is to be overcome, these conveyors are also called screw pumps. This way of water transport is very efficient and also waste water can be handled in this way. These screw pumps mostly are driven by means of an electric motor with heavy industrial gearboxes or with geared motors and an open transmission to reduce the speed, with which a water displacement can be reached of even more that 11 m3 per second.

Planetary gearboxes versus industrial gearboxes
The heart of the so called screw pump is the gearbox. Traditionally standard gearboxes and industrial gear units are used. Aandrijf Technisch Buro thinks that there are a lot of chances for planetary gearboxes. For both power transmission principles there are advantages as well as disadvantages to be regarded. For example the thermal capacity, weight, way of bearing arrangements and purchase costs. The costs for a planetary transmission, at equal output torque and lifetime, are much lower than the traditional transmissions. This cost advantage is a result of the much more efficient way to use the “steel“. The disadvantage can be that a planetary unit often needs an external cooling system because of the much more compact way of building the unit and as a result of a much smaller amount of cooling oil. But an external cooling system on a gearbox has also other advantages for the power transmission like for example a much longer lifetime.

Gearboxes mounted in an angle
Since a screw pump can be used to overcome a height difference of even more than 25 meters, the gear units will have to be mounted in an angle to the horizontal line. Planetary gearboxes can be mounted in an angle without any problems and can be supplied with several different in- and output shafts, with standard or increased bearing capacity. Both shafts, in- as well as output shaft, are in line with the conveyor shaft and if used a shaft mounted version there is no aligning problem. If a more compact unit is needed, more and more planetary units with bevel input stage are used.

Reliability and costs
Many purification plants are working 24/7 to be able to cover the demand of fresh water. The price for fresh water in The Netherlands is very low. For less than € 0,01 per liter we have clean fresh water coming out of the tap. In average we use about 120 liters per person per day. For purification processes we calculate with 150 liters. The complete production process has to be very effective and efficient. Aandrijf Technisch Buro advises already at the engineering stage regarding the investments to keep the Total Cost of Ownership ( TCO ) as low as possible. Added value is offered by advice in the complete power transmission concept and the realization of it. So we do not only offer a piece of the jigsaw puzzle, but we put the pieces together to solve the complete puzzle.