Numerical Simulation Of Low Nox Emissions Mechanism In Catalytic Combustion Of Methane

The emission of NOx produced by the traditional natural gas flame combustion has caused great harm to the environment and human health,and the catalytic combustion mode can achieve low Nox emissions.The NOx emission characteristics of a catalytic burmer are affected by both operating parameters and reactor parameters which require in-depth analysis and research.In this paper,Fluent is used to simulate the catalytie combustion process of methane.The main work is as follows:(1)Mathematical model of catalytic combustion and NOx generation process was improved.A two-dimensional single-channel model of a honeycomb catalytic burner was established.The catalytic reaction mechanism of methane on the surface of Pt and the gas phase reaction mechanism GRI3.0 of methane were involved.The temperature field,velocity field,methane concentration field,HC and CO emissions,NOx composition,formation rate and mechanism in the tunnel under different operating conditions such as methane concentration,inlet velocity,inlet temperature,and different reactor parameters such as reactor length and reactor pore size were numerically simulated.The results show that using the two-dimensional model,the influence of velocity,temperature and composition concentration distribution in the radial direction of the reactor on the nombustion characteristics and pollutant emission characteristics of the reactor were analyzed,compared with experimental results,the catalytie combustion process of methane is predicted more accurately.(2)The methane catalytic combustion characteristics and NOx generation process of different inlet operating conditions and reactor structural parameters were systematically studied.The methane concentration,preheating temperature and iulet gas velocity have a great influence on the combustion characteristics and pollutant emission characteristics of the catalytic burner.The concentration,temperature and gas velocity should be carefully chosen to reduce the reactor length and reduce pollutant emissions.Under certain operating conditions,there are optimized values for reactor length and pore size to minimize pollutant emissions and improve reactor performance.(3)The formation mechanism of NOx in the catalytic combustion of methane was studied.The formation mode of Nox is related to the operating conditions and reactor parameters.In the catalytic combustion of methane,the formation of thermal Nox and prompt NOx should be mainly considered,and intermediate NOx should also be considered in low methane concentration and gas phase combustion.