Abstract
NOx emissions during the combustion process takes place mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study intends to study numerically the problem of NOx emissions using a model of combustion chamber with 200 kW swirl burner utilizing propane as a fuel. The importance of this study is generally due to its relation to the pollutants formed by boiler furnaces and gas turbine combustion chambers, which used broadly in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations describing the turbulence, species concentrations, combustion and radiation modeling as well NOx modeling equations were solved together to represent temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of air to fuel ratio. Particularly, the simulation presented more observation on the interaction between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration increase as the oxygen percent in the oxidizer increases, but after certain threshold the NOx concentration stats to decays dramatically.