Study on preparation and combustion characteristics of oily sludge briquette

Under the background of large consumption of coal resources, difficult disposal of oily sludge and serious environmental pollution, in order to realize the resourceful and clean utilization of oily sludge, coal resources can be comprehensively utilized while disposing of oily sludge in a safe and efficient way by mixing and molding oily sludge and coal. Therefore, the coal fuel prepared by mixing oily sludge and coal was investigated, with relaxation density, relaxation ratio, crushing resistance, and water permeability resistance as the physical property indexes, to explore the optimal molding conditions of oily sludge briquette. The combustion characteristics of oily sludge briquettes under different addition ratios and heating rates were analyzed by thermogravimetric analysis, and the emission characteristics of pollutants in incineration flue gas were analyzed by flue gas analyzer. The results showed that when 20%−40% of oily sludge was added, the molding pressure was 20 MPa, and the moisture content of the mixed raw materials was 10%, the relaxation density of oily sludge briquette increased to more than 1 g/cm³, and the resistance to crushing was more than 90%. The physical properties of the coal became better, and the molding effect was better. The addition of oily sludge effectively improved the ignition performance and combustion characteristics of coal. When 40% of oily sludge was added, the calorific value of the produced coal fuel was 19.43 MJ/kg, and the stable combustion characteristic index was the largest, which was 3.10×10⁻⁵%/(min·℃²). In addition, increasing the reaction temperature can contribute to the emission of NO and SO₂. When the reaction temperature is 900 ℃ and below, the emission of NO and SO₂ can be better controlled without affecting the emission concentration of PAHs and heavy metals, which is lower than the limit value of pollutant emission standard. The mixing of oily sludge and coal is an effective way to realize energy saving and emission reduction. The addition of oily sludge reduces the ignition temperature of the coal, the burn-out temperature, and improves the combustion performance while effectively controlling the emission of pollutants.