Decanter centrifuge
A centrifuge is a device that employs a high rotational speed to separate components of different densities.
This becomes relevant in the majority of industrial jobs where solids, liquids and gases are merged into a single mixture and the separation of these different phases is necessary.
A decanter centrifuge increases the rate of settling through the use of continuous rotation, producing a G-force equivalent to between 1000 and 4000 G's.
Through the feed, the separation medium to be processed can be input into the centre of the infeed chamber of the scroll, where it is accelerated.
These openings contain precisely adjustable weir discs/weir plates by means of which the pond depth in the bowl can be set.
The main application of decanter centrifuges is to separate large amounts of solids from liquids on a continuous basis.
[5] The vertical decanter allows for high temperature and/or high-pressure operation due to the orientation and the rotational seals provided at one end.
[5] Capacities range up to 40,000 pounds (18,000 kg) of solids per hour with liquid feed rates of up to 300 US gallons (1.1 m3) per minute.
A decanter centrifuge applies a force equivalent to several thousand G's, which reduces the settling time of the particles.
Higher G-force results in an increase in the separation of the solid particles from the liquid and yields a better clarity.
[10] Design heuristics are methods based on experience which serve the purpose of reducing the need for calculations with regards to equipment sizing, operating parameters or performance.
This is to optimise economic value since smaller scale processes do not necessarily require such costly equipment to attain the desired product.
A low cone angle is beneficial when solids do not compact properly and possess a soft texture.
Additionally, low cone angles result in a lower wear rate on the scroll and are beneficial when being used with very compact solids requiring a large magnitude of torque to move.
[10] In the cylindrical section of the decanter centrifuge, the pool should ideally be shallow in order to maximise G-force for separation.
[5] The production of a waste stream is small in comparison to the overall process output; however can still pose a number of significant problems.
The objectives of post-treatment vary between different industries where in order to perform an efficient and economical process; the decanter centrifuge must be tailored to the task at hand.
[5] Sedimentation of the suspended solids occurs as normal where they accumulate on the wall of the bowl and are conveyed out of the centrifuge.
There are numerous manufacturers specialising in mechanical separation technology that have adopted these new designs into industry standard equipment.
Other designs can reduce power consumption by up to thirty percent due to a large slurry discharge, and are best utilised in the water treatment industry.
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 way in which manufacturers aim to address this is by utilising variable mechanical devices in the rotating part of the decanter centrifuge.
Another area of development in recent years is the implementation of Functional Safety measures, aiming at providing a better and more safe working environment.
