Screw Pumps and Hydropower Screws
A screw pump is used to pump large amounts of liquids over a limited head. The main applications of screw pumps are water management in canals and rivers as well as the transport of contaminated water into waste-water treatment plants (return sludge screw, influent pump).
Hydropower screws produce electric energy by turbining an amount of liquid from a higher to a lower level. The electro-mechanical design is similar to that of a screw pump.
Vandezande supplies very high-quality screw pumps and hydropower screws and offers the possibility to combine both techniques in one single screw body. The conflicting preconditions in terms of optimum fluid levels are accommodated at the upper level by a hydraulically driven jacket valve, which also allows flow control (depending on the rotational speed) during the turbine operation, and at the lower level by means of adapted blades.
The major advantages of screw pumps and hydropower screws are:
- high flow rates;
- high efficiency;
- high reliability;
- low maintenance;
- long service life (little wear);
- fish-friendly and easy to apply in natural streams (thanks to the atmospheric operating principle and the relatively low nominal speed);
- easily accessible;
- ability to run dry for long periods of time.
At Vandezande, a screw pump unit consists of the following main components:
Screw pump body
The screw pump body consists of a central tube or beam on which blades are welded to form a continuous spiral thread. Depending on the flow required, a double or multiple-bladed spiral is used.
Screw pump trough
In addition to the custom-made concrete trough for the screw pump installed, it is also possible to choose either a steel trough mounted together with the screw in a rectangular concrete trough, or a self-supporting prefabricated steel unit which is provided with the necessary supports. With this latter option, the screw pump is supplied with trough and drive line as one unit.
The purpose of this attachment is to minimize leakage by increasing the filling rate of the screw pump and the efficiency accordingly.
The grease-lubricated upper bearings absorb both axial and radial forces. The bearing housing is either wall-mounted or floor-mounted. The axial and radial bearings have an automatic adjustment so that angular deformations caused by the deflection of the screw can be absorbed.
The self-adjusting lower bearings only absorb radial forces and allow for thermal expansion of the screw. The lower bearings are mounted in a cast-iron housing with an alloy specially designed for this application. Different types of lower bearings are available: with grease lubrication, oil lubrication or without lubrication (ecological bearings).
The driving unit consists of an asynchronous motor connected to the fast-rotating shaft of a helical or parallel gearbox through a belt transmission or elastic coupling. The low-speed shaft of the gearbox is connected to the screw pump shaft by means of an elastic coupling. Screw pumps are provided with a backstop brake in the gearbox. Hydropower screws are provided with an external brake fitted on the fast-rotating shaft of the gearbox.
Environmentally conscious infrastructure
Vandezande’s activities all fit within the scope of working on an environmentally conscious infrastructure. The construction of new locks to take transport off the road and group it in the form of shipping transport in order to further...