Pyrolysis of lime dried sewage sludge in a fixed-bed reactor: Effects of the addition amount of lime
The production of sludge is substantial, and its water content is extremely high. The gas and bio-oil produced through sludge pyrolysis can be reused as energy sources or industrial raw materials. Lime (main component: calcium oxide, CaO), a cost-effective and widely used sludge dewatering conditioner, generates calcium hydroxide (Ca(OH)<inf>2</inf>) during the sludge drying process with lime. This compound elevates sludge pH and significantly influences product distribution during sludge pyrolysis. This study investigated the effects of Ca(OH)<inf>2</inf> addition ratios (Ca/SS = 0, 0.25, 0.5, 1, 1.5, and 2) on three-phase product release characteristics during lime-dried sludge pyrolysis. Experiments were conducted in a fixed-bed reactor at 500 °C to examine these effects. The results revealed that Ca(OH)<inf>2</inf> substantially modifies pyrolysis behavior through two principal mechanisms: enhanced CO<inf>2</inf> adsorption leading to promoted H<inf>2</inf> generation, and catalytic effects on key chemical transformations. These include decarboxylation and decarbonylation of oxygenated bio-oil compounds, and nitrogen-containing ring-opening reactions coupled with molecular rearrangements. These synergistic processes collectively increase aromatic hydrocarbon yield while producing small-molecule gases, ultimately improving both hydrogen production efficiency and bio-oil quality during sludge pyrolysis. © 2025 Elsevier B.V., All rights reserved.
Библиографическая ссылка Lin Dan, Kai Wantong, Xie Xing, Isa YusufM., Kozlov AlexanderN., Penzik MaximV., Zhang Shihong, Li Bin Pyrolysis of lime dried sewage sludge in a fixed-bed reactor: Effects of the addition amount of lime // Fuel. Vol.405. ID:136767. 2026. DOI: 10.1016/j.fuel.2025.136767
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