Research on combustion characteristics and ash properties of municipal sewage sludge

Author(s): Wenjun Yang, Zhiwen Xu, Yungang Wang, Zhiyuan Liang, Qinxin Zhao
Xi’an Jiaotong university, No.28 Xianning West Road, Xi’an, 710049 Shaanxi, China
International Journal of Smart Grid and Clean Energy, vol. 8, no. 4, July 2019: pp. 408-414
ISSN: 2315-4462 (Print)
ISSN: 2373-3594 (Online)
Digital Object Identifier: 10.12720/sgce.8.4.408-414

Abstract: In this study, the combustion characteristic of municipal sewage sludge(MSS) was investigated using non-isothermal thermogravimetric analysis at different heating rates (5°C/min, 10°C/min and 20°C/min), and the ash properties under different combustion temperatures were studied by means of X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that there were four main stages during combustion process of MSS: dehydration, de-volatilization and combustion of volatile, combustion of char and residual organics, and burnout. The SEM micro-morphology analysis indicated that loose ash particles with porous structure gradually transformed into large aggregates with dense structure with an increase in combustion temperature from 575 ℃ to 1000°C, and MSS ash sintered severely under 1000°C to form materials with high strength. The XRD results indicated that the main minerals in MSS ash were quartz (SiO2) and hematite (Fe2O3). Under high temperature, minerals reacted with each other to form eutectic compounds with low melting point, leading to severe sintering and melting of MSS ash.

Keywords: Municipal sewage sludge, thermogravimetric analysis, combustion, ash properties
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