Cyclones

Cyclones are widely used industrial dust collectors. In general, a cyclone consists of a vortex-forming gas inlet, an axial clean gas outlet and a dust discharge opening. The performance of a cyclone is determined by the dust holding efficiency and pressure drop. The design criteria of the cyclone can be either high efficiency or high capacity depending on the intended use. Therefore, there is no single optimum design method for cyclones.

Cyclones have an important place among dust collection technologies. These systems are specifically designed to separate fine dust particles from the air stream. The rotating air stream pushes the dust towards the outer walls of the cyclone, where it is separated from the air. The effectiveness of industrial cyclones depends on particle size, airflow velocity and cyclone design. While these devices are vital in waste management and air quality control, they are also a preferred solution in terms of energy efficiency and operational efficiency. Cyclones are becoming even more effective and environmentally friendly thanks to continuously developing technologies.

Cyclones are devices with fixed (immobile) parts that convert a gas stream containing solid grains into a vortex movement with certain boundaries due to the tangential inlet effect and are used to clean the gas by separating the solid grains from the gas with the help of centrifugal force acting on the grains. In practice, cyclones with a wide variety of geometries are available. However, the most widely used cyclone type in gas cleaning is the ones with tangential inlet, single cylinder and single cone and axial outlet.

In order to design a new cyclone system or to improve an existing system, the cyclone efficiency and the pressure drop in the cyclone must be accurately predicted. There are various approaches for this, depending on assumptions about the gas characteristics and the movement of the particles in the cyclone. The pressure drop in cyclones is generally proportional to the square of the gas inlet velocity and lies between 6 and 200 mm water column. In many theories developed to determine the pressure drop in cyclones, kinetic energy loss due to rotation in the cyclone and losses due to wall friction effects are taken as the most important factors. Since the dust entering the cyclone does not generally have a single grain size, the fractional retention efficiency for each grain size is referred to and is defined as the ratio of the weight of that grain fraction retained in the cyclone to the total weight of the fraction entering the cyclone. Dust retention efficiency generally increases with increasing grain size and density, gas inlet velocity, cyclone vortex rotation velocity and cyclone length, decreasing cyclone diameter and gas viscosity and density, drawing some gas from the dust outlet and wetting the cyclone walls.