Investigation on the influence of non-thermal plasma on reaction degree of wood gasification in a drop tube reactor

The influence of non-thermal plasma (NTP) on entrained-flow wood gasification at atmospheric pressure was investigated in experiments performed at a drop tube reactor with an inner diameter of 0.1 m. Three particle size categories covering diameters between 125 and 700 mu m were used for testing. NTP and thermal gasification were compared applying similar experimental conditions in order to study the contribution of radicals, excited species, and charged particles to the gasification reaction. In case of NTP gasification about 1 kW of electric power was supplied to the preheated steam, whereas in case of thermal gasification the preheated steam was superheated applying about the same heat rate. Due to thermalization the temperature flow-down of the NTP zone approached the temperature after thermal superheating. The syngas-based carbon conversion degree was calculated from the ratio of the carbon content of the gaseous products (CO, CO2 and CH4) to that one of the original feedstock. Results show that NTP enhances syngas production for at least 20% and carbon conversion for 27% compared to thermal gasification. Kinetic rate coefficients for syngas formation as a function of temperature were obtained by fitting the syngas based carbon conversion degree assuming a first order reaction and temperature dependency described by the Arrhenius equation. For NTP gasification reaction rate coefficients increased by 33% as compared to thermal gasification were achieved.