The study of co-gasification characteristics of sewage sludge and palm kernel shell

Abstract

Sewage sludge (SS) is a by-product of wastewater treatment plants It can be treated as municipal solid waste and usually disposal of by landfills in Taiwan Due to the complicated chemical compositions it is prone to generate toxic gases such as dioxin and polychlorinated biphenyls for incineration The resulting fly ash may also contain heavy metals such as chromium (Cd) and lead (Pb) that become a direct threat to human health and the environment In this study the sewage sludge is converted to syngas by gasification However sewage sludge possesses low energy density and high ash and moisture content that would lead to difficulty for utilization Therefore palm kernel shells (PKS) are used for co-gasification to reduce the difficulty of feeding and improve the quality of syngas This study starts from the fuel property analysis and then uses a thermogravimetric analyzer integrated with Fourier transform infrared spectroscopy (TG-FTIR) to explore the co-pyrolysis/gasification characteristics of sewage sludge and palm kernel shells The activation energy is calculated by using the FWO method with different heating rates The results also show that there exists a synergistic effect during the reaction From the gas yield the case of biomass blending ratio (BBR) =20 30 40 % have revealed a lower tar yield and NH3 production than pure PKS and pure SS in the syngas Finally a 1 kWth continuous feeding type fluidized-bed reactor is designed and built for isothermal gasification test The best-operating conditions of maximum cold gas efficiency (CGE) H2/CO ratio and H2 concentration are found through the Taguchi method respectively According to the result it shows that the parameter combination of temperature blending ratio carry gas CO2/(CO2+H2O) ratio and catalyst addition to achieve maximum CGE is 900 °C 0 % 100 % and 15 %; for maximum H2/CO ratio is 900 °C 30 % 70 % and 20 %; for maximum H2 concentration is 800 °C 40 % 70 % and 15 % respectively

Date of Award	2020
Original language	English
Supervisor	Yei-Chin Chao (Supervisor)