title: Experimental investigation of ash deposits on convection heating surfaces of a circulating fluidized bed municipal solid waste incinerator.
abstract: Incineration of municipal solid waste (MSW) is a waste treatment method which can be sustainable in terms of waste volume reduction, as well as a source of renewable energy. During MSW combustion, increased formation of deposits on convection heating exchanger surfaces can pose severe operational problems, such as fouling, slagging and corrosion. These problems can cause lower heat transfer efficiency from the hot flue gas to the working fluid inside the tubes. A study was performed where experiments were carried out to examine the ash deposition characteristics in a full-scale MSW circulating fluidized bed (CFB) incinerator, using a newly designed deposit probe that was fitted with six thermocouples and four removable half rings. The influence of probe exposure time and probe surface temperature (500, 560, and 700°C) on ash deposit formation rate was investigated. The results indicate that the deposition mass and collection efficiency achieve a minimum at the probe surface temperature of 560°C. Ash particles are deposited on both the windward and leeward sides of the probe by impacting and thermophoretic/condensation behavior. The major inorganic elements present in the ash deposits are Ca, Al and Si. Compared to ash deposits formed on the leeward side of the probe, windward-side ash deposits contain relatively higher Ca and S concentrations, but lower levels of Al and Si. Among all cases at different surface temperatures, the differences in elemental composition of the ash deposits from the leeward side are insignificant. However, as the surface temperature increases, the concentrations of Al, Si, K and Na in the windward-side ash deposits increase, but the Ca concentration is reduced. Finally, governing mechanisms are proposed on the basis of the experimental data, such as deposit morphology, elemental composition and thermodynamic calculations.
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy & Environment, Southeast University, Nanjing 210096, China. Electronic address: tangzhi@seu.edu.cn.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy & Environment, Southeast University, Nanjing 210096, China. Electronic address: xpchen@seu.edu.cn.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy & Environment, Southeast University, Nanjing 210096, China.
authors.forename: Daoyin
authors.initials: D
authors.lastname: Liu
authors.affiliation: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy & Environment, Southeast University, Nanjing 210096, China.
authors.forename: Yaming
authors.initials: Y
authors.lastname: Zhuang
authors.affiliation: Zhejiang Fuchunjiang Environmental Thermoelectric Co. Ltd., Fuyang 311418, China.
authors.forename: Minghua
authors.initials: M
authors.lastname: Ye
authors.affiliation: Zhejiang Fuchunjiang Environmental Thermoelectric Co. Ltd., Fuyang 311418, China.
authors.forename: Hongchan
authors.initials: H
authors.lastname: Sheng
authors.affiliation: Zhejiang Fuchunjiang Environmental Thermoelectric Co. Ltd., Fuyang 311418, China.
authors.forename: Shaojuan
authors.initials: S
authors.lastname: Xu
mesh_terms: D018481:Convection; D006358:Hot Temperature; D017745:Incineration / Q000379:methods*; D062611:Solid Waste; D014866:Waste Products / Q000032:analysis*
chemical_list: D062611:Solid Waste; D014866:Waste Products
keywords: Ash deposition; Circulating fluidized bed; Fouling; Inorganic element; Municipal solid waste