Waste heavy oil sludge is considered oil waste that can be utilized as a renewable energy source. Although it has high calorific values, it should be treated as a designated waste. During the recycling process of construction and demolition wastes or the trimming process of woods, a lot of sawdust is produced. In this study, the feasibility of BOF (biomass and waste heavy oil sludge fuel) as a source of renewable energy was estimated. To investigate its combustion characteristics, a lab scale batch type combustion reactor was used, and temperature fluctuation and the flue gas composition were measured for various experimental conditions. The results could be summarized as follows: The solid fuel pellets manufactured from waste heavy oil sludge and sawdust had C 50.21 ~ 54.77%, H 10.25 ~ 12.66%, O 25.84 ~ 34.83%, N 1.01 ~ 1.04%, S 1.03 ~ 1.07%. Their lower heating values ranged from 4,780 kg/kcal to 5,530 kg/kcal. The density of the solid fuel pellets was increased from 0.63 g/cm3 to 0.85 g/cm3 with increasing the mixing ratio of waste heavy oil sludge. The maximum CO2 concentration in the flue gas was increased with increasing waste heavy oil sludge content in BOF. SO2 concentration in the flue gas was showed a tendency such as the highest CO2 concentration in the flue gas. With increasing waste heavy oil sludge content in BOF, the combustion time became rather shorter although the increase of the CO2 concentration in the flue gas was delayed. Because the carbon conversion rate showed small difference with increasing the mixing ratio of waste heavy oil sludge in BOF, BOF with the mixing ratio of waste heavy oil sludge of 30% was effective for combustion. With increasing the mixing ratio of waste heavy oil sludge in BOF, activation energy and the amount of total CO emissions were increased, while activation energy was decreased with increasing the air/fuel ratio. Therefore, the optimal air/fuel ratio for the combustion of BOF was 1.5.

Waste heavy oil sludge is considered oil waste that can be utilized as a renewable energy source. In this study, an attempt has been made to convert the mixtures of waste heavy oil sludge and sawdust into solid biomass fuels. The solid fuel pellets from waste heavy oil sludge and sawdust could be manufactured only with a press type pelletizer. The mixing ratios of waste heavy oil sludge and sawdust capable of manufacturing a solid fuel pellet were 30 : 70, 40 : 60 and 50 : 50. Ultimate analysis result revealed that these mixtures had C 50.21 ~ 54.77%, H 10.25 ~ 12.66%, O 25.84 ~ 34.83%, N 1.01 ~ 1.04%, S 1.03 ~ 1.07%. With increasing the mixing ratio of waste heavy oil sludge, the carbon and hydrogen content in solid fuel pellets were increased, while the oxygen content was decreased. But the nitrogen and sulfur content in solid fuel pellets did not show much difference. Their lower heating values ranged from 4,780 kg/kcal to 5,530 kg/kcal. The density of the solid fuel pellets was increased from 0.63 g/cm3 to 0.85 g/cm3 with increasing the mixing ratio of waste heavy oil sludge and the collapse of the solid fuel pellets occurred at a moisture content of 21%. As the mixing ratio of waste heavy oil sludge in the solid fuel pellets was increased, the reaction of thermal cracking became faster. It was also observed that the solid fuel pellets were thermally decomposed in two steps and their DTG curves were simpler with increasing the mixing ratio of waste heavy oil sludge. The activation energy and the pre-exponential factor of the solid fuel pellets ranged from 18.90 kcal/mol to 21.36 kcal/mol and from 201 l/sec to 8,793 l/sec, respectively. They were increased with increasing the mixing ratio of waste heavy oil sludge.