Study On Properties Of SO₂Absorption/Desorption And Mass Transfer In Aqueous Organic Amine Solution In A Packed Column

As a new flue gas desulfurization technology, amine wet-type flue gasdesulfurization process has the advantages of high desulfurization efficiency, lowercosts, no secondary pollution and regeneration of absorption solution easily.In this paper, SO2in simulated flue gas was absorbed with the dynamic absorptionand absorbents were regenerated at95℃by nitrogen stripping. Absorption andregeneration properties of different absorbents were compared, such asmonoethanolamine (MEA), Diethanolamine (DEA), methyldiethanolamine (MDEA),and N-(2-Hydroxyethyl) piperazine (HEPZ). The effects of the content of HEPZ inabsorbing solution and pH, absorption temperature, SO2concentration in simulatedflue gas, the rate of liquid to gas flow rate on desulfurization and desorption weresystemically investigated. The results showed that HEPZ had the best properties ofabsorption and desorption. The optimum conditions in absorption process were fixedas following: the absorbent concentration of0.1mol L-1in absorbing solution, pH of4.73, absorption temperature of45℃, gas flow rate of300L/h and liquid flow rateof5L/h. The properties of different piperazines organic amines of PZ, HEPZ, PA-Ain the recycles of absorption and desorption and selective absorption ability werecompared. The saturated absorption capacity of PZ is higher than that of HEPZ andPA-A. The efficiencies of desorption and anti-oxidation of PA-A is better than that ofPZ and HEPZ. PA-A has the better selective absorption to SO2.Based on Two-film theory, the absorption of SO2into aqueous MEA solution was analyzed inpacked column. The gas volumetric overall mass transfer coefficient (KGa) could be calculatedwithK a G1d lnyG(p)dzbased on the differential method. The influences of various processparameters on KGa were researched, including the ratio of liquid to gas (L/G), pH value of initialabsorption solution, concentration of MEA in liquid-phase, system temperature and theconcentration of SO2in inlet gas. The results showed that the KGa increased with increasing MEAconcentration of absorption solution, the L/G and initial pH value, decreasing absorptiontemperature and the concentration of SO2in inlet gas. An empirical correlation of KGa for SO2absorption with aqueous MEA solution was developed using the obtained experimental data, asshown belowKGa2.2336(L0.6792G), when the reaction. temperature was45℃, MEA concentration of absorption solution was0.01mol/L with initial pH5.94, SO2concentration in inlet flue gas was4500ppm.