Numerical Simulation Of Ammonia Denitration Of Spray Scattering Tower Based On Ozone Pre-oxidation

Since the emission by coal-fired power plants is continually rising and contains a high concentration of nitrogen oxides,it has been an urgent need for power plants to be equipped with De-NOx systems in the near future to meet the even more strict criteria.As a brand new desulfurization and denitration equipment combining the advantages of spray tower and bubble tower,spray scattering tower has demonstrated its bright development and application.Basing on the theory of pre-oxidation of ozone,ammonia denitration technology shows a high cooperativeness in working with desulfurize and economical efficiency,and therefore could be used as one of the technical options for emission pollution treatment.This thesis took the ozone dosing equipment from an environmental protection company as the research object,and established the physical and mathematical model and chemical reaction model basing on existing reaction mechanisms.The simulation results would be compared with the actual operating conditions to verify the model mentioned above,and to study how different factors would effect onto the oxidation reaction,and suggestions were put forward to optimize the ozone pre-oxidation process.As a result,the verified model was entitled to be applied to simulate the ozone pre-oxidation process in spray scattering tower.In the spray scattering tower,mathematical models of gas-liquid flow and heat and mass transfer process would be established respectively basing on its technological characteristics,divided it into spray area and bubble area.In this model,the Euler-Lagrange model would be used to describe the gas-liquid flow in the spraying area,and the Euler-Euler model would be used to describe the gas-liquid flow in the bubbling zone,and a mass transfer absorption model for ammonia denitration would be established based on the duo-membrane theory.In this thesis,a 5000Nm~3/h spray scattering tower would be used to numerical simulation,and would be verified via physical and chemical model basing on the experimental results of actual operation.Then analyze the process of how does the gas-liquid flow and heat and mass transfer in the tower,and to understand the denitration mechanism within the process,and to investigate how does different liquid-gas ratio,the flow rate of flue gas,the O3/NO ratio and the immersion depth of scattering tube effect the denitration efficiency of spray scattering tower.Conclusions could be drawn as:the denitration rate would increase following with increase in the liquid-to-gas ratio,which is mainly reflected in the spray area;the denitration rate would decrease with the increasing flue gas flow;the denitration rate could be boosted by increasing the O3/NO molar ratio,but the increasing rate would demonstrate a negatively decreasing trend;the effect of denitration in the bubbling area would be facilitated by increasing the immersion depth of the scattering tube.Finally,according to the effect and principle of the operating parameters on the denitration effect of the spray scattering tower,and combing with the actual situation,it could provide optimization guidance for the operating parameters of the demonstration project in the near future.