Experimental Study On Absorption Of As₂O₃ In Flue Gas By Spray-and-scattered-bubble Technology During Limestone-gypsum Desulfurization Process

In addition to the coal-fired boiler pollutants（SO₂,NO_x,PM）,toxic trace elements were also produced by coal-fired power plants.Arsenic is a common heavy metal element in flue gas,which has the characteristics of high toxicity,volatile and bioaccumulation.Adsorption method is the most mature technology for arsenic removal from flue gas,but the initial investment and operation cost of power plant will be increased.More and more research focus on the utilization of the existing pollutant control technology and equipment to avoid extra energy input.In this paper,the arsenic absorption characteristics were studied in lab-scale spray-and-scattered-bubble scrubberand the effects of liquid gas ratio,immersion depth,mass fraction of Ca CO₃ solution and inlet SO₂ concentration on the removal of arsenic were further discussed.The results showed that the arsenic removal efficiency firstly increased and then tended to decrease with the increase of Ca CO₃ mass fraction and inlet SO₂ concentration,when the inlet SO₂ concentration reaches 1500×10^-6,the arsenic removal efficiency reaches the maximum.With the increase of liquid gas ratio,the arsenic removal efficiency increases,while the arsenic removal efficiency will decrease with the immersion depth.Furthermore,the grey relational analysis was used to rank the factors affecting the system.The evaluation results showed that the influence of four main process parameters on the arsenic removal efficiency is Ca CO₃ mass fraction>liquid gas ratio>inlet SO₂concentration>immersion depth,which provides a guiding method for industrial optimization operation process.Adding ozone pre oxidation device to carry out arsenic removal experiment,the effects of O₃/NO molar ratio,Ca CO₃ mass fraction,inlet SO₂ concentration,liquid gas ratio and immersion depth on arsenic removal efficiency were explored.Similarly,The results showed that the arsenic removal efficiency firstly increased and then tended to decrease with the increase of Ca CO₃ mass fraction and inlet SO₂ concentration,when the inlet SO₂ concentration reaches 1500×10^-6,the arsenic removal efficiency reaches the maximum.With the increase of liquid gas ratio,the arsenic removal efficiency increases,while the arsenic removal efficiency will decrease with the immersion depth.Furthermore,the grey relational analysis was used to rank the factors affecting the system.The evaluation results showed that the influence of four main process parameters on the arsenic removal efficiency is Ca CO₃ mass fraction>liquid gas ratio>inlet SO₂concentration>immersion depth.