Experimental study on steam gasification of pine particles for hydrogen-rich gas

Adopting the self-built experimental setup on high temperature steam gasification of biomass, which takes advantages of the downdraft gasifier, the experimental study uses pine particles made of pretreatment sawdust for hydrogen-rich gas. Experimental tests show that the pine particles are converted into hydrogen-rich synthesis-gas efficiently, and the output is more stable in the course of the experiment. According to the experiments, the gasification reaction becomes severer with the increase of temperature, the volume fraction of H2 increases from 23.38% at 700 °C to 44.79% at 950 °C, which nearly doubles, but this value drops slightly because the CO-steam shift reaction is inhibited after the temperature reaching 900 °C. The volume fraction of CO reaches the minimum value at 850 °C, and then increases with the increase of temperature. The volume fraction of CO2 decreases slowly with the increase of temperature. The increasing of gasification temperature intensifies the reforming reaction of hydrocarbons with high temperature steam. With the increase of steam flow from 0.3 kg·h−1 to 0.9 kg·h−1, the volume fraction of H2 increases from 37.1% to 47.7% at the gasification temperature of 900 °C. The change of the volume fraction of CO is stable, while the volume fraction of CO2 increases after it reaches the minimum value of 13%, and the volume fraction of CnHm decreases slowly. Considering the quality of gasification gas, when the steam flow rate is 0.6 kg·h−1 and gasification temperature is 900 °C, gasification gas yield and hydrogen yield reach the maximum value of 2.69 m3 kg−1 and 1.02 g kg−1 respectively, and the ratio of the amount of steam and biomass is about 0.95 at this time in the reaction. In addition, under the conditions of the same temperature and steam flow rate, with the increase of mass percent of limonite added, the biomass carbon conversion and gas yield show an increasing trend while the lower calorific value of gasification gas decreases. When the gasification temperature is 700 °C and steam flow rate is 0.9 kg·h−1, addition of 15% of iron ore powder causes the increase of the volume fraction of H2 to 64.8%, while the volume fraction of CO, CH4 and CnHm (n ≥ 2) decreases, the volume fraction of CO2 increases relatively. This indicates that iron ore powder is helpful for promoting the reforming reaction of hydrocarbon with steam and reducing the energy consumption in the gasification reaction.