Experimental Research On Simultaneous Desulfurization And Denitrification Of Coal-fired Flue Gas

Air pollution is one of the serious problems facing by human beings today.As the main source of energy in the world today,coal combustion produces flue gas which is the material cause of air pollution.Coal combustion will not only cause severe smog,but also sulfur dioxide（SO₂）and nitrogen oxides（NO_X）.These two substances are the main causes of acid rain and photochemical smog,and they are also important factors in air pollution.Therefore,it has become an urgent task to deal with the SO₂and NO_Xproduced by coal burning in a method suitable for my country’s national conditions to solve the problem of air pollution in my country.Nowadays,the most commonly used desulfurization and denitration technology in the world is limestone-gypsum desulfurization and combined selective catalytic reduction（SCR）technology for denitration.However,this method has a large area,high equipment investment,and high catalyst cost.The problem has brought a huge burden to the development of the enterprise.Therefore,finding a desulfurization and denitrification method with low cost and high removal rate is of great significance to the sustainable development of the economy and society.The plate pressure drop is an important factor affecting the stability of the sieve tray tower and the operating cost of the sieve tray tower.Factors such as gas flow rate,liquid flow rate,sieve plate opening rate,hole size,etc.,have an important influence on the operating conditions in the sieve plate tower during gas-liquid reaction.Generally speaking,to increase the gas-liquid reaction rate,the plate pressure drop needs to be appropriately increased,while the decrease of the plate pressure drop can reduce the operating cost of the sieve tray.Experiments were conducted under short residence time conditions,and a desulfurization and denitrification reagent suitable for industrialization was found,and the factors affecting its desulfurization and denitrification were explored.The results show that the system composed of sodium hypochlorite（NaClO）,sodium chlorite（NaClO₂）and sodium carbonate（Na₂CO₃）is an excellent composite absorbent for desulfurization and denitrification.The composite absorbent mainly removes SO₂and NO through the synergistic effect between the oxidants NaClO+NaClO₂,and the addition of Na₂CO₃can play a buffering effect and increase the duration of the oxidants.The composite absorbent system has many influencing factors in the reaction process,and the reaction mechanism is complicated.At the same time,the composite absorbent system has high desulfurization and denitration efficiency,simple equipment and process,and low cost.Under the best conditions,the removal rate of SO₂is 100%,and the removal rate of NO is 95.63%.Anyway,the NaClO/NaClO₂+Na₂CO₃absorbent system used in this study has a lower cost and a higher removal rate,and is an economical,reasonable,and industrialized integrated desulfurization and denitrification absorbent.At the same time,this research provides ideas for the development of new wet coal-fired flue gas desulfurization and denitrification reagents.