Investigation of Non-Thermal Plasma Assisted Charcoal Gasification for Production of Hydrogen-Rich Syngas

Abstract

The motivation of this work is to investigate experimentally the influence of non-thermal plasma (NTP) application on the reaction kinetics of atmospheric pressure steam gasification of charcoal using a thermostatically controlled drop tube reactor. A gliding-arc generator provides about 1 kW electrical power NTP. For comparison thermal gasification is investigated under comparable flow and specific energy input conditions providing additional heat to the steam. Optical temperature measurement 20 cm flow down of the NTP zone is utilized to characterize the specific enthalpy of the reactive flow. The composition of produced syngas is measured by a gas analyzer and used for the calculation of gas flow rates. The results show a NTP-enhancement on the production of individual syngas components (H2, CO, CH4), especially on hydrogen production by around 39%. The syngas-based carbon conversion and hydrogen release are calculated from the carbon and hydrogen balance between the correspondent content in syngas and in the feedstock. The NTP promoted the carbon conversion and hydrogen release by 25% and 31%, respectively. The first-order reaction kinetics are determined by data-fitting in an Arrhenius diagram. The plasma enhanced the reaction rate coefficients by 27%. Based on experimental results and other literature, possible plasma-induced reactions are proposed.Novelty statement: Non-thermal plasma application has been claimed for decades to enhance the syngas yield of reforming and gasification as compared to conventional thermal processes because of its potential for efficient radical formation at comparatively low temperature. Here evidence is given for this hypothesis by characterizing the enhancement in syngas yield in steam gasification experiments where a fraction of the heat supplied to the process is substituted by electric energy supplied to a non-thermal plasma. Highlights:  NTP-Enhancement in syngas-based carbon conversion by 25%  NTP-Enhancement in syngas-based hydrogen release by 31%  NTP-Enhancement in reaction kinetics (reaction rate coefficient) by 27% A Pre-exponential factor BDE Bond dissociation energy DC Direct current EA Activation energy Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 31 January 2019