Characterization of dried sewage sludge for co-firing in coal power plant by using thermal gravimetric analysis

Abstract

This research studied the characteristics of dried sewage sludge using TGA to co-fire dried sewage sludge with coal in power plants. The sewage sludges that were discharged from Daejeon, Korea were dried and examined fundamental properties to use them as a fuel. Also, the properties of bituminous coal and wood pellet, which are used in domestic coal power plants, were analyzed and compared with them of sewage sludges and non-isothermal analyses of dried sewage sludges were performed at the heating rates of 5, 10, 20, and 30C /min using TG analyzer to investigate the basic combustion characteristics. As a results of these TGA/DTG analyses, sewage sludges showed its primary peak at the temperature of 250–500 °C, which overlapped with main peak of wood and secondary peak at around 500–600 °C, which overlapped with main peak of coals. Also for the interpretation by Friedman method, the activation energies in the section of highest weight loss were 525.16 kJ/mole for dried digested sewage sludge, 544.88 kJ/mole for dried excess sewage sludge, 203.86 kJ/mole for wood pellet and 146.4585 kJ/mole for bituminous coal. The reaction orders for dried digested excess sewage sludge, dried excess sewage sludge, wood pellet and bituminous coal were 28.775, 24.319, 18.398 and 9.1005, respectively, and the frequency factors were 5.89 $\times \hspace{0.17em}$10²⁸, 1.65 $\times \hspace{0.17em}$10^24,, 9.59 $\times \hspace{0.17em}$10¹⁶ and 1.77 $\times \hspace{0.17em}$10⁸ for each, respectively.