Numerical simulation of NOx emission characteristics of ultra-supercritical thermal power units under approval system
Focusing on the approval system for new thermal power projects,taking a new 1 000 MW four wall tangential coal-fired boiler of a certain ultra-supercritical thermal power unit as the research object,a 1∶1 solid modeling was conducted.Based on FLUENT numerical calculation software,a reasonable mathematical model was selected,and numerical simulation methods were used to study the effects of excess air coefficient,coal mill combination formula,and load changes on the NOx generation characteristics of the boiler.The results showed that when the excess air coefficient in the furnace was between 1.1 and 1.15,lower NOx emissions and higher combustion efficiency can be achieved.When all six layer burners were put into operation,the boiler generated a large amount of NOx during combustion.When the five layer burner was put into operation,the combination mode of the coal mill was ABCDE,which achieved the lowest NOx emission.When the combination mode was BCDEF,the NOx emission concentration was the highest.The decrease in load led to a decrease in the temperature level in the furnace and a reduction in NOx emissions,but the airflow organization and combustion degree were poor.
ultra-supercriticalNOx formation characteristicscoal-fired boilersexcess air coefficientnumerical simulationapproval system
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