Experimental And Kinetic Study On The Enhanced Absorption Of SO₂ NO_X Into Aqueous Solution Containing Hydrogen Peroxide

Semi-dry flue gas desulfurization techniques are more and more widespread used in small and medium-sized units because of its relatively simple system and lower capital and operating costs. The absorption-oxidation of SO₂ and NOx into aqueous solution containing hydrogen peroxide in the flue gas treatment process with multi-fluid alkaline spray generator was proposed to solve the problems in semidry flue gas desulfurization such as the lower desulfurization efficiency,the effective utilization of desulfurization products and simultaneous desulfurization and denitration. Some works have been done on a laboratory-scale spray reactor to study the SO₂ and NOx removal efficiency. Moreover, the kinetics of SO₂ absorption at different reaction systems of aqueous solution containing hydrogen peroxide was performed in a double-stirred reactor with a plane gas–liquid interface.With the improvement of the original laboratory-scale spray reactor, the effects of hydrogen peroxide solution concentration,Ca/S (N) molar ratio and spray water flow rate on the removal efficiency were investigated on it. The results show that the SO₂ removal efficiency increases 15% to 20% with the increasing concentration of hydrogen peroxide solution when hydrogen peroxide solution is sprayed to humidify Ca(OH)2 particles. The further investigation on the flue gas denitrification and simultaneous removal of SO₂ and NO show that NO removal efficiency is not obvious which is about 5% when hydrogen peroxide solution is sprayed to humidify Ca(OH)2 particle, but the SO₂ removal efficiency increases significantly. In this paper, a double-magnetic stirring gas-liquid reactor was set up to study the absorption kinetics. To measure the absorption rate of SO₂ at various operating conditions; follow by using H2O2 solution, Ca(OH)2 slurry and Ca(OH)2-H2O2 solution, respectively, to determine the chemical kinetics data.The result shows that when absorpting SO₂ with aqueous solution of H2O2, the absorption rate increases by increasing the SO₂ concentration, and the increasing H2O2 concentration has a positive effect on the absorption rate of SO₂. The absorption of SO₂ is close to completely gas-film controlled where the H2O2 concentration is greater that 0.02M. The result shows that the absorption rate decreases by increasing temperature. We get the reaction kinetics equation from different absorbent concentration absorbs different SO₂ concentration. And experimental results also indicate the effect of SO₂ concentration and absorbent concentration on the absorption rate of SO₂ when absorpting SO₂ with Ca(OH)2 slurry and Ca(OH)2-H2O2 solution has similar rules with when absorpting SO₂ with aqueous solution of H2O2. The reaction is considered to be 0.5 order with respect to reactant SO₂ under the Ca(OH)2 slurry system and the absorption of SO₂ is close to completely gas-film controlled where the Ca(OH)2 concentration is greater that 0.05%.