Energy and Exergy Analysis of Palm Tree Pruning Residues Gasification

Abstract

Gasification is the process of obtaining syngas containing combustible gases such as H2, CO and small amounts of CH4 from biomass by performing partial combustion with a limited oxygen supply or with the help of suitable oxidants such as CO2 and water vapor. The efficiency of the gasification process is the most important parameter that determines the success of the system. In this study, the performance of the system in the gasification of palm pruning residues was evaluated by energy and exergy analysis methods. The gasification process was carried out at 7.6 Nm3/h and 10.2 Nm3/h air flow rates in the laboratory type fixed bed downdraft gasification unit manufactured in the Biosystems Engineering Department. The lower heating value of the syngas obtained as a result of gasification was found to be 4.09 MJ/Nm3 at 7.6 Nm3/h air flow rate and 3.76 MJ/Nm3 at 10.2 Nm3/h air flow rate. It has been observed that the lower heating value of the syngas is lower at high air flow rate. Energy efficiencies of the gasification system at 7.6 and 10.2 Nm3/h air flow rate were calculated as 47.6% and 52.8%, and exergy efficiencies were calculated as 43.7% and 48.1%, respectively. Exergy efficiencies were found to be lower than energy efficiencies in both air flow rates. However, as the air flow rate increased, the energy and exergy efficiencies also increased. The results obtained are similar to the results of previous studies on gasification of biomass.