Computational modelling of a bagasse-fired furnace - effects of fuel moisture

The effects of bagasse moisture, a well-known source of ignition instability in bagasse-fired furnaces, was investigated using the three dimensional computational fluid dynamics (CFD) package, FURNACE. The modelling was conducted with fuel moisture contents in the range from 46% to 65% (on a wet basis) for Pleystowe No. 2 boiler and showed a dramatic shift in the location of the ignition front once the fuel moisture reached 65%. This matched well with peak fuel moistures measured during predictions are also compared with measurements of gas temperatures taken in the ignition region of a bagasse stream close to the pneumatic spreader. The predictions were also strongly affected by the presence or absence of bagasse burning on the grate which appeared to have a stabilising effect on ignition both in the model and with earlier observations by Dixon of the Pleystowe No. 2 boiler.