Effect of Thermal Conditioning on Combustion and Pollutant Emissions Characteristics of Sewage Sludge

Abstract:

Thermal conditioning (TC) can improve sludge mechanical dewaterability and drying performance, and produce solid fuel from sewage sludge with low-cost and harmlessness. This study investigates the influence of the TC on sludge combustion with thermogravemetric analysis of sewage sludge with/without TC. The experiments were carried out at a 150 mL/min air ambient with a heating rate of 10, 20, 30, 40, 50 °C/min. Tow integration approximation methods (Coats-Redfern and Flynn,-Wall-Ozawa) and a differential method (Kissinger method) were applied to study the kinetics. The Coats-Redfern method requires assuming the reaction’s kinetic mechanism. The calculated activation energy was lower than that from the Flynn-Wall-Ozawa and Kissinger, which were very close to each other. Among these methods, the Flynn-Wall-Ozawa can predict the energy required at every combustion stage, which therefore would be the best one to explore the combustion mechanism. The results show that the organic matters within sewage sludge are much more homogeneous after TC. The combustion of the thermal conditioning sludge (TCS) is much more stable with a 10% reduction in burnout time and a 9.94% reduction in combustion temperature range. The ignition temperature of the raw sludge keeps increasing from 188 to 224 °C with the heating rate, while that of the TCS is almost constant at 222-240 °C. The TC can improve the activation energy, which is about 144.52 and 123.00 kJ/mol for the raw sludge (RS) and TCS. Considering the gaseous pollutant emissions, the TC can dramatically reduce NO emissions, which is decreased from 14.22 to 6.59 mg/g by the TC, representing a reduction of 50.7%. Therefore, the TC can promote the hydrolysis of macromolecular organics, which would improve the sludge combustion performance, and reduce the gaseous pollutant emissions from combustion.

• Periodical: Advanced Materials Research (Volumes 726-731)
• Pages: 2030-2035
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.726-731.2030
• Online since: August 2013
• Authors: Shi Fu Ge, Pei Tao Zhao
• Keywords: Combustion Characteristic, Dynamic, NO Emission, Thermal Conditioning, Thermogravimetric (TG) Analysis

References

[1] P. Zhao, S. Ge and K.Yoshikawa, in: the fourth International Conference on Applied Energy. Suzhou, China. 2012: p.3179

[2] P. Zhao, S. Ge and K. Yoshikawa: Applied Energy (2013).

[3] P. Zhao, S. Ge, C. Zhang, Y. Li, W. Yan and Z. Chen: Trans. CASE Vol. 28 (2012), p.165

[4] S. Ge, P. Zhao, Y. Li ang, W. Yan and Z. Chen: Proceed. CSEE Vol. 32 (2012), p.110

[5] M. H. Lopes, P. Abelha, J. F. S. Oliveira and I. Cabrita: Environ. Eng. Sci. Vol. 22 (2005), p.205

[6] H. Xiao, X. Ma and K. Liu: Energ. Convers. Manage. Vol. 51 (2010), p. (1976)

[7] Q. Wang, L. Zhang, A. Sato, Y. Ninomiya, T. Yamashita and Z. Dong: Proceeding of the Combustion Institute Vol. 32 (2009), p.2701

[8] M. E. Sanchez, M. Otero, C. Gómez and A. Morán: Renewable Energy Vol. 34 (2009), p.1622

[9] Y. Liao and X. Ma: Appl. Energy Vol. 87 (2010), p.3526

[10] J. Jiang, X. Du and S. Yang: Waste Manage. Vol. 30 (2010), p.1407

[11] T. Murakami, Y. Suzuki, H. Nagasawa, T. Yamamoto, T. Koseki, H. Hirose and S. Okamoto: Fuel Process. Technol. Vol. 90 (2009), p.778

[12] J. Jiang, X. Du, S. Yang and Y. Zhang: China Environ. Sci. Vol. 28 (2008), p.904

[13] C. Zhang, S. Ge, P. Zhao, Y. Huang and J. Ge: Environ. Eng. Vol. 28 (2010), p.377

[14] C. Zhang, S. Ge, P. Zhao, Y. Huang and J. Ge: Acta Scient Circumstantiae Vol. 31 (2011), p.150

[15] R. Hu and Q. Shi, in: Thermal Analysis Kinetics (Science Press, Beijing 2001).

[16] P. Zhao, H. Chen, S. Ge and K. Yoshikawa, in: 5th International Conference on Applied Energy.

[17] L. Dong, S. Gao, W. Song and G. Xu: Fuel Process. Technol. Vol. 88 (2007), p.707