Demister Pad Introduction: Carry over of particulate matter by gas or vapour, generally termed as "Entrainment" is commonly encountered in Gas-Liquid separations. In many leading industries Demister Pads have gained acceptance as a low cost and highly efficient means of separating Entrained liquid droplets from gas and vapour stream. Because of simplicity of construction Demister Pads can be easily made to any shape and size to suit process configuration in existing
or new equipments.
Construction: Demister Pads are essentially porous blankets of carefully knitted wire or synthetic fibers designed and constructed to efficiently abate mist particles. After knitting each layer is corrugated and converted into Pads of different shapes and sizes. The Demister is generally supported by Grids as they are not entirely rigid.
Efficiency: When properly designed Demister Pads can give Efficiency up to 99.9% with minimal pressure drop. Normally Demister Pads can remove droplets down to 5microns and lower with a free volume of up to 99% and a surface area of
up to 1940 m2/m3. Due to high value of free volume the pressure drop across the demister pad is sufficiently low, negligible for most applications
Function: Demister Pads are installed at some distance above the surface of liquid allows free disengagement of mist droplets and the coarsest particles. The vapour/gas-liquid mixture run at a predetermined velocity through the Demister Pad, the vapour/gas finds an open path through the mesh easily, but due to greater inertia the droplets and mist impinge on the mesh and gradually increase to a bigger size and fall down due to
gravity allowing the vapour/gas to pass freely without any Entrainment from the top of the Demister Pad.
Column packing: It is used for efficient packing of
Distillation columns, which operate at Vacuum or
Atmospheric pressure. Column Packing are fabricated by knitting fine wires into a mesh then further crimping the mesh before rolling them for a desired column diameter. Multifilament mesh gives best results due to their capillary
action and promotes excellent mixing in vapour stage.
Advantages of Demister Pads:
ü Solves Emission control Problems.
ü Eliminates or reduces damage caused to the equipment
due to corrosive liquid droplets.
ü Recovery of valuable liquids.
ü Improves purity of gas/vapour for further processes.
ü Improves overall process economics.
ü Increases process efficiency.
Materials of Construction: Demister Pads are made of a variety of Materials as per application demands. A few materials of construction would be synthetic fibers, copper, aluminum, Stainless Steel 304, Stainless Steel 316, Monel, Nickel, Brass, Phosphor Bronze, Carbon Steel, etc,. for
different applications like corrosive services, nitric acids, water solutions, Freon, alcohols, fatty acids, corrosive chemicals, food products, hydrocarbons, caustic soda, dilute acids etc.
