Study On Purification Of SO₂ And NO_x In Simulated Flue Gas By Biofilm Packing Tower

The main source of energy in China is the burning of fossil fuels.Coal plays a major role in fossil fuels,and most of the energy comes from coal burning.Coal combustion is accompanied by coal-burning flue gas,which contains a large amount of SO2 and NOx,which are the main pollutants in the atmosphere.The excessive content of SO2 and NOx will lead to the formation of acid rain.Moreover,SO2 and NOx can cause damage to the human respiratory system and threaten human health.Therefore,the removal of SO2 and NOx in coal-fired flue gas is extremely important.At present,the research on simultaneous desulfurization and denitrification of biofilm packed towers is concentrated on aerobic and anaerobic methods.Among them,the aerobic flue gas desulfurization and denitrification system has an oxygen content of more than 20%and a desulfurization rate of 100.%,the nitrogen removal rate is basically maintained at 75%?80%;in the anaerobic flue gas desulfurization and denitrification system,the oxygen content is close to 0%,the desulfurization rate can reach 100%,and the denitrification rate can reach up to the low concentration NOx load.About 70%.However,the actual coal-fired flue gas contains oxygen with a volume fraction of 4%to 8%.The aerobic and anaerobic flue gases simultaneously desulfurize and denitrify,requiring a certain pre-treatment process for the coal-fired flue gas,which improves the Processing costs.Therefore,it is of great significance to reduce the SO2 and NOx in coal-fired flue gas by microbial method under the oxygen load of 4%-8%,which is of great significance to reduce the cost of coal-fired flue gas treatment.In this study,biofilm packed towers were used to purify SO2 and NO.in simulated flue gas at an oxygen content of 4%to 8%.Under the constant temperature conditions of the control system,the effects of the inlet gas concentration,the gas residence time,the intake oxygen content,the circulating fluid pH and the circulating fluid spray amount on the SO2 in the simulated flue gas under the hypoxic conditions were investigated.And the environmental factors of NOx removal rate,through the on-line detection of SO2 and NOx concentration in the inlet and outlet of biofilm packed tower,the concentration change of various components in the circulating liquid is determined,and the removal rate of SO2 and NOx by biofilm packed tower is calculated.And based on the removal rate,find the most suitable environmental factors under the current operating conditions.It was found through experiments that the biofilm packed tower was used to treat the SO2 and NOx in the flue gas.The gas residence time was 140s,the circulating liquid pH=8,the circulating liquid spray amount was 8L/h,and the oxygen content in the simulated flue gas was At 4%,the removal rate of SO2 purified by biofilm packed tower is maintained at about 98%,and the removal efficiency of NOx is good,and the removal rate can reach about 60%.It is lower than the NOx removal rate under aerobic conditions,and is not as high as the NOx removal rate under strict anaerobic conditions.In this experiment,the effect of adding metal complexing agent Fe(II)EDTA on simultaneous desulfurization and denitrification of biofilm packed tower was studied.It was found that adding Fe(II)EDTA to biofilm packed tower system can improve the mass transfer rate of NO.In order to increase the NOx removal rate,the NOx removal rate is increased from 53.95%to 67.16%.After a period of time,the Fe(II)EDTA in the biofilm packed tower could not be regenerated,and the NOx removal rate returned to the previous level,indicating that the Fe(II)EDTA has only a chemical effect on the removal rate.The physiological activity of microorganisms is increased on a biological level,and the removal rate of SO2 is maintained at about 98%,with little fluctuation.In terms of kinetics,based on the measured data,the experiment carried out related kinetic studies.Based on the theory of "adsorption-biofilm" and mathematical model,the kinetics of SO2 and NOx in simulated flue gas was purified by biofilm packed tower.The model was simulated and verified.It was verified that the purification process of SO2 and NOx in simulated flue gas by biofilm packed tower accords with the theory of "adsorption-biofilm".According to the intake concentration of SO2 and NOx in simulated flue gas,it can be calculated.The biofilm packed tower is used to simulate the removal of SO2 and NOx in the flue gas,the outlet concentration and the removal rate.At the end of this experiment,the reaction mechanism of biofilm packed tower to remove SO2 and NOx in simulated flue gas was discussed.The changes of main substances in circulating fluid were analyzed.The reaction mechanism of simultaneous desulfurization and denitrification of microorganisms was discussed.Provides general directions and ideas.