Efficient Operation of Wet Scrubbing System in Pollution Containment

摘要

Working of wet scrubbers depends on the type of gas contaminant i.e. solid, liquid and odour collection mechanisms and scrubbing liquid used. For gaseous contaminants, mass transfer is the mechanism that absorbs the gas into a liquid through creation of liquid films or droplets. Large surface area packing media, trays, fluidized beds and hydraulic or shear atomization techniques are mostly used to create the films and droplets necessary for mass transfer to occur. A chemical reagent scrubbing liquid is incorporated in many cases to enhance removal of contaminants by producing a stable salt by-product. The predominant mechanism used for particulate collection is impaction between the particle contained in the gas stream and liquid droplets. The liquid droplet encapsulates the particle into a larger size so both can be removed from the cleaned gas stream either centrifugally or by means of mist eliminator. The smaller the size of the particle the smaller the size of the droplet needed to collect the particle. Normally, a droplet no larger than 10 times the size of the particle must be used. The smaller the droplet the more energy it takes to create it either hydraulically or through gas shear effects. For hot gases scrubbing system has perfected a method to condense water vapour onto the particle to achieve a larger size agglomerated mass to increase removal efficiency at reduced energy cost. Hydrophobic particles are also hard to scrub wherein it is perfected chemical additions to the scrubbing liquid to overcome the problem. There are various control devices for controlling particulate contaminants however article covers only on the wet scrubbing system in detail.