How Does a High-Efficiency Cyclone Work?
December 2, 2015
Cyclone dust collectors remove large particles from process air as a precleaning stage in multi-stage filtration. A high-efficiency cyclone can also remove smaller particles. This makes it suitable for use as a process collector or final filter for many product recovery or pollution control applications.
A cyclone uses the natural force of a vortex or cyclone to separate particles from air. Cyclones have traditionally been used as precleaner separators to remove large particles. A well-designed, high-efficiency cyclone can capture over 99 percent of particles by weight. The particles can be as small as 5 microns, even with specific gravities of less than 1.0. A cyclone can be used in product recovery or pollution control applications that were previously considered unsuitable for the machines.
A cyclone is safer than a fabric filter because it has a much lower risk of starting a fire or exploding. It is the most suitable collector for process temperatures above 2000 degrees Fahrenheit and pressures greater than 500 atmospheres. Since it does not have filter media to replace, a cyclone is less expensive to maintain than a fabric filter.
In order to be highly efficient, a cyclone must precisely fit the variables for the application. It must have an involute inlet configuration; a long, gradual cone; a vortex-breaking hopper; and an airlock discharge.
Dust-laden air enters an inlet in the top of the cyclone. The air flows in a downward spiral against the cyclone body’s outer wall and creates an outer vortex pattern.
As air flows downward along the cone, the vortex gets smaller. The particles are separated from the air by centrifugal force and forced to the cyclone wall. A vortex-breaking hopper diffuses the vortex and pushes clean air upward through an inner vortex. The clean air exits through the cyclone roof, and captured particles are drawn into the hopper by gravity.
The vortex-breaking hopper and the airlock discharge control the balance of airflow exiting and entering the cyclone. This prevents air from entering the cyclone through the discharge and ensures that no particles from the discharge are re-entrained. The airlock discharge lets particles exit the hopper, where they can be recovered or disposed of with predictable results.