Modelling combustion in corner-fired sugar mill boilers

A computational fluid dynamics model previously developed for wall-fired boilers was modified to simulate a corner-fired bagasse furnace. The boiler enclosure was that of an existing 220 tph steam unit which is front wall-fired. Thirty percent of the combustion air was sent through the four corner firing slots and the remainder through the bottom grate. The influence of the elevation of the firing slots, the angle of inclination of the jets, the jet velocity and the distribution of grate air were examined. Corner firing can give more uniform combustion with better burnout and higher heat extraction rates than wall firing. A jet inclination close to horizontal is recommended but jet velocity has little influence on performance. Uniform distribution of grate air is recommended.