What is a Hydrocyclone?

A hydrocyclone is a filter or separator mechanism that uses centrifugal force to separate solids from liquids or even liquids of different consistencies. The hydrocyclone consists of a two-part chamber with a inner profile which is cylindrical along its upper section and conical along the lower half fitted with one entry and two exit points. When a suspension is pumped into the cyclone, it spins around the inside of the chamber creating a centrifugal force which causes suspended solids to separate from the liquid carrier. The filtered water and solids then exit the hydrocyclone, typically at opposite ends. Hydrocyclones are used extensively in industrial and manufacturing sectors and are suited for liquid rich suspensions carrying solids heavier than the fluid.

Hydrocyclones are common industrial and manufacturing process separators used to remove solids from carrier liquids or to separate liquids of different consistencies. They are simple yet efficient devices with no moving parts and requiring very little maintenance. Commonly known as cyclones, these devices are generally constructed of steel, ceramics, or abrasion resistant plastics. Typical uses of hydrocyclones are removing contaminates from paper pulp, separating of oil from water, extracting metal shavings from cooling liquids, and starch recovery from waste water in potato processing facilities. Cyclones are also found in the mining industry processing plants to separate process solids from water.

A typical hydrocyclone configuration consists of a hollow chamber that features a straight walled, cylindrical section at the top and a cone shaped section which tapers down to the lower end of the unit. The cylindrical section is equipped with two pipes, one which enters the section in the middle and one which exits on the top of the unit. A second exit point is fitted at the bottom of the cone. The suspension is pumped into the center of the cylindrical section under high pressure which causes it to spin around the inside of the chamber. The centrifugal force created in the suspension by this spinning action is the agent responsible for the hydrocyclones efficient operation.

The centrifugal action in the cyclone forces the heavier solids in the suspension against the walls of the chamber and down into the cone section. The lighter water is spun up into the top of the chamber and out of the “lights” exit. The solids collect in the cone and are forced out of the “heavies” exit at its lower end. The same action applies to fluids of differing densities with heavier oils and lighter water being separated in the same way. This centrifugal density relationship makes the hydrocyclone best suited for applications with a high water content in the suspensions and a marked density difference between the solids and fluid carriers.