An alternative approach to secondary air in bagasse boilers

An alternative to the standard approach in secondary air systems, i.e. high-pressure fan and small-bore nozzles, is described. The benefits of high-temperature air introduced at the lower bagasse chutes are described with both computational fluid dynamics and site data. The computational fluid dynamics results indicated increased turbulence in the furnace leading to higher and more uniform combustion rates. An improvement in furnace heat flux was also seen. Site data of two seasons operation with and without the new secondary air system indicated a decrease in fuel burnt on average. Operation with lower excess air was confirmed with measurements during tests on site. An improvement of combustion stability was also visually confirmed with a thermal camera and furnace pressure readings. Therefore, the safety aspect of bagasse combustion was improved due to less puffing. Key words CFD, secondary air, lower bagasse chute