Study On The Experiment Of Wet Simultaneous Removal Of SO₂ And NO_x Using Urea/KMnO₄ Solution

The atmosphere is the most basic environmental element that the mankind depends on for existence. Gas pollutants such as sulfur dioxide (SO2) and nitrogen oxide (NO_X) etc. caused by the burning of fossil fuel such as coal, petroleum and natural gas can cause increasingly serious environmental problems such as acid ran, photochemistry smog and ozonosphere destruction which made the air pollution become one of the most serious problem of the survival and progress of the human sociality, become the key factors that influence and restrict the economy and society progress of our country. While the thermal power plant is the most important emission source of SO₂ and NO_X. In China, 90% of the SO₂ and 60% of the NO_X come from coal fired gas, so it is of great importance to control the emitting of SO₂ and NO_X from the coal-fired thermal power plant. Researching and developing simultaneous desulfurization and denitrification techniques more fit for the current situation and environment protection status of our country is the important means to realize the environment protection policy and sustainable development stratagem of China.The experiment belongs to wet type flue gas treatment technique, studying the removing of SO₂ and NO_X from analog flue gas using urea and potassium permanganate solution as the absorbent. The experiment had investigated the removal effect of SO₂ and NO_X in bubbling reactor filled with steel Ball rings under static state experiment condition. On the basis of the static state experiment, the key factors and law that influence the removal efficiency of SO₂ and NO_X were studied, meanwhile, the mechanism of desulfurization and denitrification were primarily discussed.Under the condition of this experiment, the desulfurization efficiency using the absorption of pure urea can reach above 99.75%, while the denitrification efficiency is only about 40%, therefore the focal point of the experiment is in the research of denitrification. Firstly the experiment studied the impacts on denitrification efficiency using such absorbent as urea and different additives. Then potassium permanganate was chosen to be the additive of absorbent, which has the best denitrification efficiency of all the additives had ever tested. Then the influencing factors of desulfurization efficiency and denitrification efficiency such as: the concentration of the urea and potassium permanganate , inlet gas flow capacity, NO_X concentration, effective height of the absorption tower and so on were studied.Further experiment obtained fundamental rule of absorption of SO₂ and NO_Xwith analog flue gas using urea/KMnC>4 solution process, and optimized the conditions and parameters of the technique; Under the optimum conditions and parameters, dynamic experiment was carried on with absorbent spraying and circulating in single absorption column. The average removal efficiency of SO2 and NOX in the reaction time of 30 minutes was above 99.6% and 62.5% respectively. Kinetic equations of urea consumption and NH4+ formation were obtained after analyzing the absorption solution; The result shows that the urea consumption kinetic equations of single desulfurization reaction and denitrification reaction and of simultaneous desulfurization and denitrification are all linear, and reaction order is zero.The absorption velocity constant of the reaction of simultaneous desulfurization and denitrification is less than that of the reaction of single denitrification, which shows that the denitrification efficiency will decrease when SO2 exists, while the existing of NOX has no distinct effect on the desulfurization efficiency. Fertilizer can be produced from the ammonium sulfate and ammonium nitrate in the absorption solution, which has considerable economic benefit.Finally, research of pilot scale on the basis of lab scale of the laboratory was carried out. The pilot scale experiment estimated the expectative effect: the removal efficiency of SO2 and NOX were up to 86% and 60%, and the dust removal efficiency was more than 96% at the same time. Economy analysis was carried out on the basis of the pilot scale experiment.The technique of the experiment has such advantages as follows: simple equipment and manipulation; mild reaction condition (reaction temperature is about 70°C); high removal efficiency of SO2 and NOX and little secondary pollution. Because of time and limitation of experimental condition, qualitative analysis of the effect of potassium permanganate in the reaction has not been carried out, so the absorption mechanism needs further study and completion.