PRESSURE LOSS AND AEROSOL COLLECTION IN VENTURI SCRUBBER

Abstract

Wet scrubbers are being used increasingly to remove pollutant gases and aerosols, simultaneously from gaseous stream. Of all the wet scrubbers, venturi scrubbers are being preferred because of very high aerosol collection and gas absorption efficiencies and relatively simplest and cheapest design . This is the situation even when the energy consumption per unit of gas treated is highest for venturi scrubbers. The aerosol is formed by grinding or atomization of solids and liquids and by the transfer of powders into a state of suspension through the action of air currents' or vibration . The various effects of these aerosols- are bility reduction, material damage and physiological effects on men and domestic animals . In the present thesis, we present the experimental data for collection of microscopic particles in a very narrow range of 2.5-7.5 u m, in air and accompanying pressure loss in a venturi scrubber . The venturi scrubber has a throat diameter of 10 mm with Lt / Dt ratio having 3.0.. The liquid was introduced in pease-Anthony mode at the throat through 30 holes of 1.5 mm dia round the top of the throat periphery . The aerosols produced by vapouri-zing di-n-butylphthalate an oil having negligible vapour presure at room temperature . The vapours of di-n-butylphthalate condense and form a closesi ze-range aerosol particles in the gas stream . Collection efficiencies were deter-mined at various gas velocities at the throat ranging from 22.4 m / sec to 83.82 m / sec and at liquid to gas flow rate ratios of 0.59 to 4.95 1 / m3. The flow rate of di-n-butylphthalate was maintained at 160 ml/hr by fixing the glove valve at a predetermined position. The aerosol size was maintained (iv) by keeping the total heat load around the heater and pipe constant. It is found that the aerosol collection efficiency increases as the throat gas velocity and L/G ratio is increased. For our studies, we found a maximum efficiency of 69.2% at velocity of 83.82 m/sec and L/G ratio of 1.35 lhm3. The aerosol collection efficiency is found to be a strong function of the specific surface area of the liquid drops produced at the throat. The pressure drop data obtained are found to be strongly dependent on the throat velocity and L/G ratio. Our experimental datas are found to be on higher side as compared to those Virkar and Sharma