Mist eliminators, also known as demisters, are devices that remove liquid droplets or vapor from the work atmosphere. This device has found some applications in many industries where such vapors are released as a by-product of the different chemical processes. Manufacturers produce standard or specialized devices to work as an important part of various industrial operations which include absorption towers, distillation towers, separation tanks, gas separators, evaporators, and so on. Various industries like metallurgy, petroleum, medicine manufacturing use demisters in their production processes or environmental protection measures.
Working Principle of a Mist Eliminator
Standard demisting devices work on the principles of inertia and dispersion. The liquid vapor rises with the gas and passes through the eliminator pads. These pads are fitted with wire meshes with openings that correspond to the predetermined average vapor droplet size, which is generally in the range of 3 to 5 micrometers. Due to the increasing inertia of these droplets, they get attached to the wire meshes. With subsequent passes, these collected droplets get heavier and heavier due to the tensile and adhesive properties of liquids, ultimately falling off the pads. In this manner, the vapor liquid is essentially separated from the gaseous emissions passing through standard eliminator pads.
Eliminator manufacturers of today produce demisters of various sizes and capillary openings based on the above principle. A standard mist eliminator has various advantages as listed below.
· It is an essentially simple device; its size is only dependent on the gaseous emission pathway dimensions
· For such a basic device, it is highly efficient in removing liquid vapors with minimum disturbance to the actual process
· Eliminators improve the output by removing vaporized impurities; they also make gaseous emissions, safer by helping to separate potentially harmful compounds
· With no external power needed for its operation, it is a cost-saving device
· The liquid deposits may be collected and re-processed
According to the requirements of specific industries, there are various types of these devices produced and operating in several industrial applications. However, we may segregate mist eliminator devices into three basic categories as discussed below.
Standard Mist Eliminator
These are the basic demisters that may be used in normal work environments. These devices can work efficiently in standard gaseous emissions, separating liquefied vapors. The mesh sizes of these devices are bigger, and they can sustain low to moderate amounts of gas pressure.
High Efficient Mist Eliminators
These demisters are capable of efficiently handling moderate to high levels of gaseous outputs. The mesh diameters of this type of eliminator are generally smaller for higher liquid retention.
Shock Absorption Mist Eliminator
These are the optimum mist elimination devices meant for use in high-speed machines, where there is a high amount of gaseous emission in an enclosed space. These smallest mesh diameter pads can absorb liquid vapors with the highest degree of efficiency and minimum impedance.