Sawdust Combustion Research Articles

Fluidized Bed Combustion of Some Woody Biomass Fuels

In this study, the experiments of comparing cedar pellet, cypress pellet, and cypress sawdust combustion in a bubbling fluidized bed combustor (BFBC) was carried out. To improve the combustion efficiency and avoid the agglomeration, the porous alumina sand was used as bed material instead of conventional silica sand. Experimental results indicated that pellet can be sufficiently burned in the BFBC, and the CO emission was only 50–188 ppm. Meanwhile, the unburned carbon in fly ash was considerably limited even neglected; both the unburned carbon in fly ash and CO emission (3,700 ppm) was significantly high during sawdust combustion. Moreover, it was difficult to operate the BFBC above 650°C with the sawdust. Therefore, direct combustion was not a good utilization method for sawdust. It was also observed that volatile matter released from pellet volatilized and mostly burned in the dense zone due to the porous alumina. The effect of operation parameters like temperature and fluidized velocity on the pollution emission and combustion characteristic was also evaluated. High temperatures can promote the combustion efficiency, while SO2 and NOx emission is independent to temperature. As for fluidized velocity, the optimum fluidized velocity in the tests is about 0.07 m/s.

Drying of granulated wood ash by flue gas from saw dust and natural gas combustion

At the district heating plant of Kalmar, Sweden an on-line unit for production of granulated wood ash for nutrient recycling on forest soils is being applied. Currently, the granules are dried by hot air from an oil-fired burner. The objective of this work was to investigate how drying by flue gas affects the hardening of granules, or impacts their chemical composition and properties. Ninety-six granule samples were treated by flue gas from natural gas combustion in a laboratory pilot scale flue gas generator. CO 2, CO, O 2, C 3H 8 and NO concentrations were varied during the experiment. Additionally, some samples were treated by flue gas from combustion of sawdust at the heating plant in Kalmar. Drying by flue gases did not affect the chemical composition of granules, but minor effects were seen in their mineralogy. The carbonate content was slightly higher in granules treated with flue gas from natural gas combustion compared to the granules dried by hot air only, when measured by wet chemical methods. Results from XRD analysis imply that the calcite content is higher and the portlandite and arcanite content slightly less in granules treated with flue gas from sawdust combustion compared to the granules dried by hot air only. The results from this investigation showed no negative effects on ash granule composition or physical structure by the use of a flue as a drying medium.

Heat Release Measurement During Smoldering Combustion of Wood Sawdust

Heat Release Measurement During Smoldering Combustion of Wood Sawdust