A centrifuge is a piece of equipment, generally driven by an electric motor (or, in some older models, by hand), that puts an object in rotation around a fixed axis (spins it in a circle), applying a potentially strong force perpendicular to the axis (outward).
Large centrifuges can be used to simulate high gravity or acceleration environments (for example, high-G training for test pilots). Medium-sized centrifuges are used in washing machines and at some swimming pools to wring water out of fabrics.
Many centrifuges are used as laboratory or industrial equipment to separate materials, for example small molecules from large molecules. The centrifuge works using the sedimentation principle, where the centripetal acceleration causes denser substances to separate out along the radial direction (the bottom of the tube). By the same token objects that are less dense will tend to move to the top.
Most materials-separating centrifuges use liquids or a mixture of solids and liquids, but gas centrifuges are used for isotope separation, such as to enrich nuclear fuel.
Range of Centrifuge Applications
The main application of decanter centrifuges is to separate large amounts of solids from liquids on a continuous basis. They are also used to wash and dry various solids in industry, such as polystyrene beads, clarify liquids and concentrate solids.
Petrochemical/oil Industry Examples
- Oil well drilling
- Lubricating oil additives
- Waste oil stream recycling
Industrial and Biological Wastewater Treatment Industry Examples
- Municipal wastewater
- Cleaning of wash water
The rapid development of the decanter centrifuge over the 20th century saw it expand into a vast range of over 100 industrial applications. Further development since then has seen the refinement of machine design and control methods, improving its overall performance, which allows the system to respond quickly to varying feed conditions. The newest development in decanter centrifuge technology aims to achieve enhanced control of the separation process occurring inside the decanter. The way in which manufacturers aim to address this is by utilising variable mechanical devices in the rotating part of the decanter centrifuge. To control the separation process, the operational parameters should be transferred from the rotating part to the stationary part of the decanter whilst also constantly controlling and maintaining the mechanical device inside the process region. This can be achieved using hydraulic and electronic transfer systems. A hydraulic drive motor is easily able to access the rotating area of the decanter centrifuge.
There are numerous manufacturers specializing in mechanical separation technology that have adapted these new designs into industrial standard equipment. This advanced technology has allowed decanter centrifuges to operate up to 250 cubic meters per hour and has developed numerous designs such as the Z8E decanter, known as the world's largest decanter centrifuge with an adjustable impeller, which supplies a torque of 24,000 newton meters. Other designs can reduce power consumption by up to thirty percent due to a large slurry discharge, and are best utilized in the water treatment industry.