Energy & Fuels 2006, 20, 583-590
583
Partition of Heavy and Alkali Metals during Sewage Sludge Incineration Jun Han, Minghou Xu,* and Hong Yao State Key Laboratory of Coal Combustion, Huazhong UniVersity of Science and Technology, Wuhan, Hubei, 430074, People’s Republic of China
Masami Furuuchi, Takeo Sakano, and Premrudee Kanchanapiya Graduate School of Natural Science and Technology, Kanazawa UniVersity, Kodatsuno, Kanazawa, Ishikawa 920-8667, Japan
Chikao Kanaoka Ishikawa National College of Technology, Kitacyujo, Tsubata, Kahoku-gun, Ishikawa 929-0392, Japan ReceiVed May 27, 2005. ReVised Manuscript ReceiVed January 18, 2006
In this paper, two approaches are used to investigate the transformation of heavy and alkali metals during sewage sludge incineration: a thermodynamic equilibrium calculation and experiments using a bench-scale combustor. The distribution of heavy and alkali metals at different temperatures (800, 700, 600, 400, and 200 °C) is studied in these experiments. The chemical equilibrium calculation shows that vaporized metallic compounds form a condensed phase at different temperatures. The calculation results show that vaporized lead compounds begin to transfer to the solid phase at 500 °C. The main species of solid lead in the flue gas is PbCl2(s) below 500 °C. Zn and K have the same temperature range (300-500 °C), while the conversion temperature for As is 600 °C and that for Na and Cu is above 800 °C. The experimental results also prove the feasibility of separating heavy and alkali metals according to their gas-solid transformation temperature zones. On the basis of the experimental results, the optimum separation temperature is
