In the present study, a system for Combined Heat and Power (CHP) generation from mechanically dewatered Sewage Sludge (SS) is numerically analyzed through Aspen Plus software. The proposed system is composed of three consecutive processes: drying, gasification, and energy generation through an internal combustion engine. The gasification model is calibrated by applying a restricted chemical equilibrium approach and validated for four experimental outcomes available in the literature. Optimum gasification temperature (900 °C) is identified at an ideal equivalence ratio which is the ratio between actual air fed to the reactor to the stoichiometric air required for complete combustion of 0.2 predicted in a previous study through a sensitivity analysis. The CHP generation potentiality is assessed, finding 0.89 kWh/kg SS as Dry Solid (DS) of electrical and 1.67 kWh/kg of SS as DS of thermal energy. This allows supplying around 50 % of electrical energy required to run the wastewater treatment plant and is sufficient to complete the thermal drying of mechanically dewatered SS.
Combined Heat and Power Generation from Mechanically Dewatered Sewage Sludge: Numerical Modelling
Carotenuto A.;Di Fraia S.;Massarotti N.;Uddin M. R.;Vanoli L.
2022-01-01
Abstract
In the present study, a system for Combined Heat and Power (CHP) generation from mechanically dewatered Sewage Sludge (SS) is numerically analyzed through Aspen Plus software. The proposed system is composed of three consecutive processes: drying, gasification, and energy generation through an internal combustion engine. The gasification model is calibrated by applying a restricted chemical equilibrium approach and validated for four experimental outcomes available in the literature. Optimum gasification temperature (900 °C) is identified at an ideal equivalence ratio which is the ratio between actual air fed to the reactor to the stoichiometric air required for complete combustion of 0.2 predicted in a previous study through a sensitivity analysis. The CHP generation potentiality is assessed, finding 0.89 kWh/kg SS as Dry Solid (DS) of electrical and 1.67 kWh/kg of SS as DS of thermal energy. This allows supplying around 50 % of electrical energy required to run the wastewater treatment plant and is sufficient to complete the thermal drying of mechanically dewatered SS.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.