Function and applications of hydrocyclones

The Nice-based company Hectron has a range of hydrocyclones that are effective tools for separating sand from water. These devices are widely used in many fields of application and have the great advantage of optimum reliability due to the absence of any moving parts in their design. This range of hydrocyclones is designed by Hectron's research and development teams and these products are finally assembled in its workshops in Nice.

What is a hydrocyclone?

A hydrocyclone is a filtering device, but it is widely used where a filtration action is required. Upstream of a filter, the hydrocyclone will have the advantage of eliminating the largest particles and thus protecting the filter by reducing its maintenance and cleaning.

How does a hydrocyclone work?

The hydrocyclone uses the pressure of the incoming fluid to generate a centrifugal force and flow pattern that can separate particles from a liquid medium. These particles must have a sufficiently different density to the liquid medium for separation to occur.  The flow pattern in a hydrocyclone is cyclonic. This is induced by the tangential injection of the liquid into the cylindrical chamber, which causes a vortex to develop.  The chamber has a narrower axial bottom outlet so that not all the liquid in the vortex can escape through this outlet. Some of the liquid must reverse its path and flow in the opposite direction to an upper axial outlet. This reverse flow continues to rotate and a core of air develops due to the lower pressure at the axis of rotation. As a result, suspended matter accumulates downwards and falls into a tank. At the same time, the liquid drains from the centre of the chamber upwards.

The Hectron hydrocyclone range

Hectron has two types of hydrocyclones. The difference lies in the material used for their manufacture: polyamide or stainless steel.

Polyamide hydrocyclones

Hydrocyclone models made of moulded polyamide have the advantage of being economical to manufacture and avoid the hassle of oxidation that can occur with steel products.  The Alfa polyamide hydrocyclones can accept a flow rate of up to 18 m3/h. The filtration is effective on materials larger than 100 µm with 80% of these materials being filtered effectively. The maximum allowable pressure of this device is 5 Bar. There are two different sizes of this model: one with a 1" thread and the other with a 2" thread. It is also possible to have a version suitable for use with sea water.

Stainless steel hydrocyclones

Models made of HN stainless steel have the advantage of high durability and also avoid the rusting concerns of simple steel.  They can be both cylindrical and conical in shape. It is the size that determines the shape used.  The cylindrical HN model has a maximum flow rate of 25 m3/h and a pressure of up to 10 bar. The filtration is effective on 80% of materials larger than 100 µm.  Sizes available include 1" and 2" threaded inlets and outlets.  The HNc models are conical in shape. They have the same general characteristics but differ in size. They are available with 3" threaded inlets and outlets or with DN 100 flanges.

Application areas of Hectron hydrocyclones

The use of hydrocyclone technology to protect filtration systems is quite widespread and has applications in many areas. However, some of the most important ones are the following:

Filter for individual boreholes

Water wells often have the problem of water that is loaded with sand, mud, clay or other suspended matter. Filtration is of course necessary and can be supplemented with a hydrocyclone that will remove the larger particles. This will protect the filter and greatly reduce the maintenance costs of the installation.

Seawater filtration

Seawater filtration is used in many installations. It can be found in all desalination units, water purification installations for aquaculture or aquariums or even in heat exchanger protection systems. In these cases, the use of Hectron hydrocyclones in a seawater version will be recommended and will help to remove all particles that are larger than 100 µm in size in an almost natural way.

Heat pump protection in collective buildings

The heat exchangers of ground source water/water heat pumps installed in boreholes are very sensitive to clogging. This can easily occur when the pumped water is loaded with various suspended matter. This will always lead to clogging of the exchangers. It will then be necessary to dismantle the exchangers and clean them thoroughly in order to restore optimal operation. The protection offered by hydrocyclones will be invaluable: it will act as a filter that effectively removes all the larger particles. This can of course be supplemented by automatic filters.

Watering and micro-irrigation

The solenoid valves, drippers or micro-sprinklers of irrigation and micro-irrigation systems are fragile and expensive components. It is therefore necessary to provide effective filtration to protect them.  The use of a hydrocyclone is an efficient solution to avoid clogging and thus reduce maintenance (compared to traditional cartridge filters) or repair interventions.