subject: Inertial Separators: An Introduction [print this page] Combining the collective forces of gravity, inertia and centrifugal force, inertial separators fragment dust particles from flowing gases. This works by transporting the dust to an area where the force of the gas flow is very weak, allowing for the gravitational force to separate the dust and store it in a hopper.
There are three main methods for separating dust in this way. In this article, we take a look at what they are and how they work.
Baffle chamber
Baffle chambers require a fixed baffle plate to force the gas stream to change direction. The biggest particles do not flow with the gas stream and therefore fall into a separate airspace where they settle.
Settling chamber
Comprising a large container which is connected to ductwork, the chamber works to reduce the velocity of the particles as they travel amidst the airstream, resulting in the denser ones being separated out. This change in speed is achieved by increasing the size of the cavity very quickly.
Although these chambers can be constructed from a variety of materials, they are not used commonly due to the fact that they require a lot of space and are not particularly efficient. They are, however, sometimes used as a preliminary filtering system before a more effective separator.
Centrifugal collectors
Using cyclones to separate dust particles from the air, centrifugal collectors allow the dust to enter the unit at an angle, where it is then spun very quickly. Due to the powerful centrifugal force created by the air flow, the dust particles are hurled towards the outer wall. Once they hit the wall, the particles drop into the hopper and are collected.
There are three main types of centrifugal collectors.
Single-cyclone Separators
Single-cyclone separators create a dual vortex. The main vortex spirals in a downwards direction and takes the majority of the coarser dust particles with it, whereas the inner vortex spirals in an upwards direction and collects the finer dust particles.
Multiple-cyclone Separators
Consisting of several smaller cyclones, multiple-cyclone separators operate by having a main vortex which takes the denser particles downwards, and an inner vortex which takes the finer particles upwards. The advantage is that there is more than one cyclone, although they all share the same gas inlet and outlet. Similarly, they are very efficient since they are longer, which allows for a greater centrifugal force to be generated. This results in better dust extraction.
Secondary Air Flow Separators
The secondary air flow increases the speed of the cyclone, which increases its efficiency. By intercepting the particles before they reach the walls of the unit, and forcing them toward the collection area, the secondary air flow saves the unit for abrasion. It also allows for the separator to be installed in a horizontal position because gravity is not used in the separation process.
