Study On Adsorption Characteristics Of SO₂in Flue Gas On Activated Carbon And It’s Applications

In the constitution of energy consumption in our country, coal is the main energy. Air pollution caused by coal burning, has gained great attention. The industrial furnaces have been increased to over half million scattered in china, which have significant impacts on air quality, with contribution rate up to45%-65%. Considering dispersive in position, operating separately, load varying, and low running expense for these furnaces, the flue gas desulfurization plants need to have simple structure, reasonable and available process, reliable operation, and low running costs. The activated carbon desulfurization has obvious advantages of low investment of equipment, high efficient, low running cost, easy operation, reduction of the second pollution, and making use of by-product comprehensively, which can accommodateactual demand of these industrial furnaces. Therefore, activated carbon desulfurization is an efficient way to control the SO2contamination.Based on the actual requirement of the small to medium industrial furnaces in china, this work investigated the adsorption kinetics and the adsorption thermodynamic on different sizes of commonly-used activated carbons, discussed the changing of rate-controlling step at different conditions, and obtained the adsorption rate equation with a simple form and non-experience parameters. The developed model well agrees with experimental data at different SO2inlet concentrations, superficial linear velocities, flue gas temperatures, and particle sizes of activated carbon.A water soak cleaning-bed packed with wetted activated carbon was designed to study the dynamic characteristicson the wetted activated carbon. Based on the adsorption kinetics of SO2on dry activated carbons and results of previous researches on wet activated, a flue gas desulphurization simulation model using wetted activated carbon was built. The heat and SO2transfers and the drying process of the activated carbon were also investigated, which revealed the synergy effect of heat-and-wet process inside the bed on adsorptions of activated carbons under different conditions.In the end, the paper obtained the technological parameters of the desulfurizing tower, combined with the simulation model and actual conditions of the engineering. A demonstration project of activated carbon desulfurization for flue gas up to6000m3/h was built. The project systems run steadily for a long time at different furnace loadings, flue gas velocities and SO2concentrations. The outlet concentrations of SO2were considerably below emission standards, meeting the design requirement.Results of the current research will provide valuable references for understanding mass and heat transfers inside the bed, optimizing absorber structures, and improving theflue gas purification technology for middle and small coal-fired industrial furnaces.