Haver standard india private limitedhas introduced column-packing pads made from a crimped mesh of woven wire filaments. Every strand of this mesh is a bunch of a large number of thin filaments. The package is cylindrical in shape and is made to a sizethat snugly fits the interior of a distillation column., it is widely useful in laboratories, pilot plant and commercial installations, for distillation, gas-absorption and liquid extraction due to its high mass transfer efficiency. An intimate contact between vapour and liquid phases is necessary to attain high degree of mass transfer efficiency. Knitmesh made from crimped mesh of woven wire filaments gives large surface to realize the desired interphase mixing. These pads are used in separation of close boiling compounds through distillation; high vacuum distillation; and distillation of heat sensitive materials. These packing pads include following salient features:
· low values of hetp [height equivalent of theoretical plate]. Typical values range from 100 to 150 mm
· low values of pdts [pressure drop per theoretical stage]. Typical values range from 0.04 to 0.5 mm hg, depending upon the vapour load
· high vapour handling capacity: vapour handling capacity of knitmesh is comparable to 25mm metal pall rings
· no reduction in efficiency even at low liquid irrigation rates as low as 0.3 mh-1 [0.5 gpm/ft2]
· performance is independent of packing size
· no wall effect applications:
· fractionation of heavy water
· separation of o-/p-xylenes, o-/p-nitrochlorobenzenes
· fractionation of essential oils
· separation of styrene from ethylbenzene
· rectification of polyhydric alcohols [glycols]
· rectification of high molecular weight paraffins
· separation of alkylphenols
· scrubbing of acid gases such as h2s, co2, so2, ph3, nox in suitable reacting mediums
It finds applications in humidification, dehumidification, liquid extraction, direct contact heat transfer, and vapor-liquid and liquid-liquid separations
Its advantages are as given below: reduction in packed volume; reduction in the cost of column shell and supporting structure; reduction in product loss through product degradation; high flexibility; and increase in throughput capacity.
