Circulating fluidized bed combustion of meat and bone meal

Meat and bone meal (MBM) is phosphorus-rich material, which can be used as raw material of fertilizer. Prior to use, however, organic material in MBM must be removed completely by incineration. High NOx emissions during incineration of MBM are anticipated since nitrogen content in MBM is very high. In the present work MBM was burned using a bench-scale circulating fluidized bed combustor at 1123 K. MBM ash was used as bed material. Experimental results showed that NOx emissions decreased with increasing hold-up of MBM ash in the combustor. To investigate the mechanism of NOx reduction, two series of model experiments were conducted: 1) combustion of alterntive fuels (coal and soybean) using bone ash as bed material, and 2) MBM combustion in inert bed material (non-porous alumina). The former was carried out to evaluate catalytic effect of MBM ash on reduction of NOx. The latter was conducted to evaluate the effect of fluidization condition on combustion behaviour of MBM. No reduction in NOx emissions was observed during either experiment when the amount of bed material was increased. These results indicate that the combination of MBM as fuel and MBM bone ash as bed material has synergy effect on NOx reduction during combustion.