Experimental And Simulation Study On Ammonia/Air Staging Combustion In Porous Media

The utilization rate of fossil fuels in industrial production is increasing,but the pollutants produced by its combustion enter the environment,causing serious harm to the ecological environment and human health.The problem of reducing pollutant emissions needs to be solved urgently.At the same time,in response to the national development policy of"carbon neutralization and carbon peak",it is urgent to find alternative clean energy and develop new combustion technologies.Ammonia is a carbon-free fuel,and its combustion products do not contain CO₂.The storage and transportation process is mature,but its low combustion calorific value,high ignition temperature,low flame propagation speed,and NO_Xgeneration after combustion limit the actual utilization of ammonia fuel.Porous medium staged combustion technology can not only broaden the combustion range of ammonia,but also effectively reduce NO_Xemissions.Therefore,it is of great significance to study the combustion of ammonia/air premixed gas in porous media staging burners for environmental improvement.In this thesis,the self-built porous media staged burner is used.Firstly,the burner is experimentally optimized to obtain the optimal conditions of ammonia fuel in porous media.Secondly,the effects of equivalence ratio,flow rate and oxygen concentration on the combustion of ammonia fuel were studied.Based on the simplified Konnov mechanism,the NO formation sensitivity and reaction path of equivalence ratio,flow rate and oxygen concentration under constant temperature conditions were simulated.Finally,the staging combustion technology is coupled with the porous media combustion technology to study the influence of the porous media type and the location of the burnout nozzle in the burnout zone of the ammonia fuel and air staging.The simplified Konnov mechanism is used to simulate the NO generation sensitivity and reaction path of air staging under constant temperature condition.After optimizing the experimental conditions,it can be found that the combustion range of ammonia is widened and the combustion efficiency is improved when the packing height of porous media is 10cm.In the experimental and simulation study of ammonia/air combustion in porous media,NO emission increases with the increase of flow velocity and oxygen concentration,while the increase of equivalence ratio leads to the decrease of NO emission.When the oxygen concentration is 21%,the flow velocity is 0.1m/s and the equivalence ratio is 1.3,the NO emission is the low,and the value is 194ppm.The chemical reaction kinetics software verifies that the equivalence ratio and temperature are the main parameters affecting the NO generation during ammonia combustion.The increase of NO emission in flow velocity and oxygen concentration is caused by the increase of temperature.In the experimental and simulation study of ammonia/air staging combustion in porous media,the NO emission increases with the increase of the proportion of primary air,and the NO emission is 133ppm when the proportion of primary air is 80%.The types of porous media in the burnout zone from high to low are:straight hole type,foam type and no-load type,while the NO emission increases first and then decreases with the increase of the position of the burnout air nozzle.In summary,the use of porous media staging combustion technology can significantly reduce NO emission.