Combustion characteristics and kinetics study of hydrothermally treated paper sludge by thermogravimetric analysis

Abstract

The hydrothermal treatment has been utilized to improve solid fuel property of paper sludge. In this study, an investigation on combustion characteristics of the hydrothermally treated paper sludge was performed. The paper sludge was treated at the temperature range of 180–240°C under pressurized conditions with a holding time of 30 minutes by a lab-scale apparatus. After that, the optimized temperature (197°C at 1.9 MPa) was conducted to treat the paper sludge in a pilot plant with the same holding time. The combustion behavior of the products and the reference materials, including cellulose, hemicellulose, and lignin, were studied by the thermogravimetric analysis. The major decomposition of paper sludge was devoted to cellulose. The ignition temperature was originally low around 257–271°C. The burnout temperature was approximately 679–695°C. From the two-stage kinetics study, the activation energy of the treated paper sludge was lower than the original material in range of 113–147 kJ/mol.

Keywords::

• hydrothermal treatment
• combustion
• thermogravimetric analysis
• kinetics
• paper sludge

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Acknowledgements

The authors gratefully acknowledge K. Suksankraisorn and K. Phetdee from the Siam Cement Public Company Limited (SCG) for the substantial support. C. Areeprasert was financially supported by the Faculty of Engineering, Kasetsart University, Thailand.