The Mass Transfer Mechanism Between Charged Lime Droplets And SO₂

The SO₂ from coal-fired has been the great fountainhead for the environment, so it has been important and urgent task to control SO₂ emission. Gas desulphurization is the only desulphurization technology of cosmical and commercial application. The wet-calcium-desulphurization is the most maturate and reliable, which occupied the dominant position and is chemical reaction in gas-liquid. Although this technology has been the leading technology for the superiority of high SO₂ removal efficiency, run-credibility,and facile removal SO₂ dose, it is the key how to improve lime droplets spray and the SO₂ absorbency, reduce investment and the operating-cost. It is a valid approach that the technology of high voltage is introduced to gain this aim.Based on the several typical gas desulphurization and basic theory of charged spray, the model of mass transfer had been set up for confirming the mechanism of charged lime-droplets-spray. The relations of its trait, removal SO₂ effect and process had been analyzed. Through the mechanism of mass transfer some results which have classical academic signification and applied value have been gained.1. The ratio of charge to mass of spry droplets was measured through metal Net-target way, which had been showed that it had a furthest value between the flow rate and the ratio of electric charge to mass for the decided nozzle and electrode.2. The droplets' diameter was measured using PDA, and the results had been shown that charged lime droplets were well-uniform.3. The SO₂ removal efficiency had been measured in case of charged and normal indications.It was showed that the charged droplets had higher SO₂ removal efficiency.4,The model of two-film Theory was set up in the instance considering chemical reaction and charged droplets. The mass transfer rate, gas phase transfer coefficient, liquid phase mass transfer coefficient, gas phase overall mass transfer coefficient and enhancement factor in the different charged lime had been analyzed.It has been shown that the distribution of charged droplets is well-uniform, the large area of gas-liquid, the strengthened activity, the increased mass transfer rate, and high SO₂ removal efficiency. The calculation model of mass transfer has responsed the process of the absorbed SO₂ and also indicates that charging is valid for SO₂ removal efficiency.