Spent Activated Carbon Combustion in a Fluidized-Bed Combustor

Abstract

Spent activated carbon (SAC) from wastewater treatment plants is not allowed to be regenerated in Taiwan, and landfill is the only legal way for disposal. Owing its high heating value, SAC can be a potential source of energy from waste. In this study, SAC is used as the fuel in a vortexing fluidized-bed combustor. The combustion characteristics and pollutant emissions are investigated at various operating conditions. Results show that the primary gas flow rate and in-bed stoichiometric oxygen ratio have a significant impact on the bed temperature. The bed temperature increases with the in-bed stoichiometric oxygen ratio, while the bed temperature decreases significantly with the primary gas flow rate. In comparison to the primary gas flow rate and excess oxygen ratio, the in-bed stoichiometric oxygen ratio plays a dominant factor for the combustion fraction in the bed zone and CO/NO x emissions. The combustion fraction in the bubbling-bed region increases, while the CO emission decreases significantly with the in-bed stoichiometric oxygen ratio. In this study, all NO x emission concentrations are within the limit of Taiwan Environmental Protection Agency (EPA) regulations.

Recently Detected Drinking Water Contaminants: GenX and Other Per‐ and Polyfluoroalkyl Ether Acids

“…Finally, questions about the management of spent GAC with adsorbed PFASs remain. Management options for spent GAC include landfilling, incineration, and thermal reactivation (e.g., Pancras et al , Duan et al , Chowdhury et al ). In the case of landfilling, the PFAS desorption potential from spent GAC needs to be studied.…”

Utilization of an Organic Calcium Compound to Reduce SO2 and NO Emissions from Sewage Sludge Combustion

“…In these tables, the value of probability > t is the discrimination index on the influential degree of the factor. In this study, this threshold was set as 0.05; that is, when the value of a factor is greater than 0.05, the degree of influence of the factor falls outside the 95% confidence level …”

“…In this study, this threshold was set as 0.05; that is, when the value of a factor is greater than 0.05, the degree of influence of the factor falls outside the 95% confidence level. 21 Tables S1−S4 in the Supporting Information present the probability values obtained using the second-order model. For example, in the Table S1, X 2 and X 3 (main effects) are lower than 0.05, which suggests that they have a significant effect on the mean SO 2 emission.…”

“…The Box–Behnken design offers an advantage when investigating three factors, as fewer experimental runs are required compared with other experimental designs . The three-level, three-factorial RSM design is given in Table .…”

“…The Box−Behnken design offers an advantage when investigating three factors, as fewer experimental runs are required compared with other experimental designs. 21 The three-level, three-factorial RSM design is given in Table 2. The three factors are the air flow rate (Q), the Ca/S ratio (R), and the reaction temperature (T), with initial values of 350 mL/min, 1.0, and 700 °C, respectively.…”