Demister pad, also known as defoamer, screen defoamer, mesh defoamer, fog catcher, mist eliminator, used for gas entrained fog separation tower, to ensure the efficiency of filtration.
In the late fifties, a device made of a special wrinkled woven mesh removed inclusions of tiny liquid bubbles from gases. Then it was found that the efficiency was very high and the resistance was very small, which was incomparable to other gas-liquid separation devices, so it was widely accepted and widely used.
The defoamer pad is generally arranged at the top of the packing tower, which can ensure the mass transfer efficiency and reduce the plate spacing. Defoamer is widely used in chemical, petroleum, pharmaceutical, light industry, metallurgy and other industrial production of vertical cylindrical equipment vapor-liquid separation device. It can also be used in desulfurization and other production to remove oil mist, toxic and harmful gases.
When the gas with mist rises and passes through the wire mesh at a constant speed, the rising mist will collide with the wire and attach to the wire surface due to inertia. The mist will spread on the wire surface and the droplets will move along the wire where the two wires meet. Until the gravitational force of the droplets exceeds the upward force of the gas and the surface tension of the liquid, and there is very little gas passing through the demister pad, the droplets will gradually become larger and separate from the filaments.
Separation of the gas in the droplets can improve operating conditions, optimize process indicators, reduce corrosion of equipment, extend equipment life, increase the processing volume and recovery rate of valuable materials, protect the environment and reduce air pollution.
Simple structure.
Light weight and easy to transport.
High porosity, small pressure drop.
Large specific surface area, high separation efficiency.
Easy to install, operate and maintain.
Durable and long service life.
Corrosion and rust resistant.
Demister pad,Efficiency is initially a function of droplet size, filament size, mesh specific surface area, mat thickness, and physical characteristics of the system. For a standard size mesh mist eliminator (filament diameter 0.28 mm, density 145 kg/m3, surface area 300 m2/m3), the removal efficiency is typically 100% for droplets 5 μm in diameter and larger. The use of higher surface area defoamer mats 500 m²/m3 with a reduced diameter of 0.15 mm can be used to increase the removal efficiency.
Demister pads can be installed horizontally or vertically. The horizontal airflow through the demister has a capacity of 305 more than the vertical airflow, so the demister can be smaller.
Demister pads are typically 150 mm thick with a 25 mm thick grid on both sides for a total thickness of 200 mm. Years of experience have shown that a pad thickness of 150 mm provides optimum performance in hydrocarbon processes with vertical airflow configurations.
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