| dc.description.abstract | This research investigates the evaluation of energy conversion, gasification products partitioning characteristics, and trace pollutants (e.g., sulfur and chlorine) in co-gasification of sewage sludge (SS) and anaerobic digestate (AD) using fluidized bed gasifier with controlling equivalence, temperature (700~900°C), blending ratio of 1:1, 2:1, 3:1, 1:2 and 1:3 at 900°C.
In the case of SS gasification, the hydrogen production was increased from 3.69 vol.% to 19.05 vol.% with the temperature rising from 700°C to 900°C. Meanwhile, hydrogen production increased from 3.11 vol.% to 14.54 vol.% in AD gasification. It implied that hydrogen production increased with an increase in temperature. The heating value of product gas was increased from 3.48 MJ/Nm3 to 6.62 MJ/Nm3 and 2.35 MJ/Nm3 to 7.10 MJ/Nm3, respectively. The cold gas efficiency (CGE) significantly increased from 16.32% to 31.10% and 11.87% to 35.88%, respectively. Based on the results of energy conversion efficiency, increasing the temperature will enhance the endothermic reactions such as the Boudouard reaction, water-gas reaction, and tar cracking.
In the case of SS and AD co-gasification with a temperature of 900°C, increasing the AD addition ratio could enhance the produced gas heating value. In the case of SS: AD = 3:1, the maximum hydrogen production was 19.07%. In the case of SS: AD = 1:3, the maximum gas heating value was 6.98 MJ/Nm3, and the CGE was 34.60%. The total energy recovery rate ranged between 30.25% and 47.28% in the co-gasification of SS and AD. According to the results of the sulfur and chlorine emission characteristics. In the case of SS and AD co-gasification, the sulfur and chlorine partitioning in the gas phase was above 80%. In the case of AD, SS, and SS: AD = 1:3, the concentration of hydrogen sulfide in the syngas were 227.64 ppm, 177.66 ppm, and 201.2 ppm, respectively. Air pollution control technologies must be planned to reduce the chloride and sulfide emissions in the syngas.
In summary, the experimental results verified that sewage sludge and anaerobic digestate could be used as co-gasification materials and feasibility of improving energy yields. Therefore, the results of this study could provide good information for energy conversion technologies′ selection of digestate after the anaerobic digestion process. | en_US |