CFD Investigation Of The Effect Of Tilt Angles To Flow And Combustion In A 120 Mw Gas-Fired Full Scale Industrial Boiler

Abstract Extensive Computational Fluid Dynamic simulations on combustion process in a 120 MW natural gas-fired industrial boiler have been performed. The boiler is of tangential system by which natural gas and air are fired into the furnace from its four corners at three different elevation levels. Fuel burners and air nozzles can be tilted in the range of 30.The simulation results show good prediction of temperature profile and distribution as compared to practical observation. The flow in the furnace is highly swirling with intense mixing of natural gas and air. The turbulence level is extremely high and combustion gas flows in helical shape in anti-clockwise direction towards the furnace exit. The results revealed the importance of the effect of heat transfer to the water wall as the temperature distribution and flow pattern is significantly difference with heat transfer and without heat transfer cases. Temperature distribution prior to the entry to the re-heater elevation is non-uniform with lower velocity at vortex core where the fireball is located. The average temperature at re-heater level reduces when the burner is negatively tilted up to -10. A slight change in firing angle will interrupt the temperature and flow contour at furnace-re-heater. However this is only true for air nozzles where the overall flow pattern inside the furnace is dominated by these sources..