Experimental Study On Simultaneous Removal Of SO₂and NO_x In A Tower By Alkali Absorption Based On Accurate Control Of The Rate Of NO₂/NO_x By Adding NO₂

With the increasingly stringent national emission standard of atmospheric pollutants,combined removal of atmospheric pollutants technology has become the focus of currentresearch. In this paper, studying a method used alkali absorption to removal SO₂and NO_xatthe same time combine with adding NO₂to control of the rate of NO₂/NO_xand transformingthe structure of absorption tower.First of all, the method of this experiment is using NaOH for the absorption liquid,combining with compounding NO₂to regulate the oxidizability of NO_x, and using thesieve-plate tower to remove SO₂and NO_x. In order to analysis the feasibility of adding NO₂to control of the rate of NO₂/NO_x, and find out the effect factors of the absorption efficiencySO₂and NO_x, such as concentration of absorbing liquid, velocity of flue gas,NO₂/NO_x（volume ratio） and the concentration of SO₂and NO_xwere researched. The resultsshow that when the velocity of flue gas is0.7m/s, the volume ratio of SO₂and NO_xin the fluegas is8×10^-4, NO₂/NO_xis0.5, L/G is4L/m3,and the concentration of NaOH liquid is2%, thedesulfurization efficiency is almost97%, and denitrification efficiency can be87%. It alsoshow that the method which adding NO₂to control of the rate of NO₂/NO_xis feasible.The second, this article use lime slurry as absorption liquid, and start experiment whichuse simulated flue gas to remove SO₂and NO_x. At the same time increase denitrationefficiency through the way that regulation the oxidation extent of NO_xthrough add NO₂. Thispaper mainly studied several factors that affect the efficiency of denitration. such as theliquid-gas ratio、the temperature of absorption liquid、NO₂/NO_x（volume ratio）、concentrationof SO₂and so on. The result of experiments told that under the condition that flue gas velocitywas7m/s, volume fraction of SO₂was5.5×10^-4and volume fraction of NO was3×10^-4,NO₂/NO_xwas0.5, liquid-gas ratio was4L/m3,the lime slurry at298K, the absorptivity ofSO₂and NO_xcan respectively reach96.63%and88.36%, it realized the goal thatdesulfurization and denitration in the same tower.Meanwhile，during the study of simultaneous desulfurization and denitrification by alkalisolution，we also found that NO₂can improve NO absorption not only NO and NO₂cancombined the form of N₂O₃, but also they maybe exist the similar catalytic role. When SO₂and NO_xto be absorbed, there is a mutual influence. The amount of SO₂can help theabsorption of NO_x, but the high concentration of SO₂can be restrain denitrification.The last, this article has also deal with the denitration serous. We selected two oxidations（O2and H₂O₂） to oxide NO₂^-. It have researched the pH value，reaction temperature，oxygen content，the consumption of H₂O₂and Fenton reagent affect the oxygenation efficiency ofNO₂^-. The results have showed that the oxidation rate of NO₂^-will increase with the increaseof reaction time and decrease with the increase of pH value. Use H₂O₂or Fenton as oxidizingreagent will have better result than use O2. If use H₂O₂to take an experiment, the result ofoxidation can almost reached100%when C （H₂O₂）/C （NO₂^-）≥1, and C（Fe2+） almost cannoteffect the result of experiment.