Deep Removal Of Sulfur Dioxide In Flue Gas By High Gravity Wet Method

The content of carbon dioxide （CO₂） in the flue gas was about12%. Emissions of CO₂influe gas increased the greenhouse effect, as well as, the growth of vegetables in greenhousesneeded to add CO₂regularly.If CO2in flue gas used in greenhouses, the depth needed for removing SO₂so that itcould not affect the growth of crop. When the content of CO₂was12%, the concentration ofSO₂was1428mg/m₃, the concentration of SO₂in the flue gas should be removed to14.3mg/m₃at least.But current researches rarely achieved the above requirements, which using GB100mg/m₃as the target, could not meet the requirement of deep desulfurization. Thetraditional tower equipments had lower desulphurization efficiency and covered an area oflarge. The high gravity rotating packed bed could strengthen mass transfer and increase therate of desulphurization. Deep removal of SO₂in flue gas with rotating packed bed was putforward combine with the greenhouse vegetables on the growth of the requirement of deepdesulphurization and high gravity rotating packed bed superiority was studied.Three kinds of absorption liquid （sodium hydroxide, sodium carbonate and sodiumsulfite） were used for desulphurization, the desulphurization effects were contrast researched.The influence laws of various operation parameters on the desulphurization effects wereinspected, which purpose was to seek the optimal process conditions. The concentrations ofCO₂in flue gas were also investigated, to calculate whether we could achieve the purpose ofdeep desulphurization and greenhouses to fill CO₂.Experiments showed that, the desulphurization efficiency increased with the increasingliquid-gas ratio, high gravity factor and the concentration of absorption, and decreased withthe increasing capacity when sodium hydroxide was used as absorbent. The suitable operationconditions were determined for the concentration of SO₂in flue gas was less than1428mg/m₃.The suitable operation conditions of desulphurization with sodium hydroxide solution were asfollows: the liquid gas ratio was from1.25L/m₃to1.75L/m₃, the high gravity factor was from 63to98, the concentration of absorption was from0.05mol/L to0.0625mol/L. Under theseconditions, removed the concentration of SO₂was less than1428mg/m₃from flue gas, the rateof desulphurization was higher than99%. The concentration of export SO₂was lower than14.3mg/m₃, which could achieve the purpose of deep removal of SO₂. However, theshortcoming was that the removal rate of CO₂was67.1%, which was bad for capture andreuse of SO₂.Experiments showed that, the desulphurization efficiency increased with the increasingliquid-gas ratio, high gravity factor and the concentration of absorption, and decreased withthe increasing capacity when sodium carbonate was used as absorbent. The suitable operationconditions were determined for the concentration of SO₂in flue gas was less than1428mg/m₃.The suitable operation conditions of desulphurization with sodium carbonate solution were asfollows: the liquid gas ratio was from1.5L/m₃to1.75L/m₃, the high gravity factor was from63to98, the concentration of absorption was from0.0625mol/L to0.075mol/L. Under theseconditions, removed the concentration of SO₂was less than1428mg/m₃from flue gas, the rateof desulphurization was higher than99%. The export SO₂concentration was lower than14.3mg/m₃. The removal rate of CO₂was only14.3%, which could meet the requirements ofthe greenhouses to fill carbon.Sodium sulfite solution was used as absorbent. Experiments showed that, thedesulphurization efficiency increased with the increasing liquid-gas ratio, high gravity factorand the concentration of absorption. The appropriate operation conditions were as follows: theliquid gas ratio was from2.5L/m₃to4L/m₃, the high gravity factor was from98to150, theconcentration of absorption was from0.075mol/L to0.1mol/L. The operation conditions ofsodium sulfite were appearing to be much different from both sodium hydroxide and sodiumcarbonate, which leaded to increase costs. Therefore, sodium sulfite was not considered fordesulphurization absorbent.Based on the research on flue gas desulphurization experiment, the suitable absorbentwas selected, which was sodium carbonate. Desulphurization with sodium carbonate solution,the SO₂in flue gas could be deeply removed; the CO₂also could be retained. Flue gas afterdesulphurization could be used in vegetable greenhouse in the demand for carbon source.