Rapid Pyrolysis of Wheat Straw in a Bench-Scale Circulating Fluidized-Bed Downer Reactor

Intermediate Pyrolysis of Brewer’s Spent Grain: Impact of Gas Atmosphere

This work focuses on the impact of carrier gas on the quantity and quality of pyrolytic products received from intermediate pyrolysis of the brewer’s spent grain. In this study, three types of carrier gases were tested: argon, nitrogen, and carbon dioxide at three temperatures of 500, 600, and 700 °C. On the basis of the process conditions, the yield of products was determined. The ultimate analysis of the char was performed, and for selected chars, the combustion properties were determined. Gas chromatography of the organic fraction of oil was performed, and the compounds were determined. Additionally, microscale investigation of the spent grain pyrolysis was performed by thermogravimetric analysis. The results showed that there were no significant differences in product yields in various atmospheres. Char yield changed only with temperature from 28% at 500 °C up to 19% at 700 °C. According to ultimate analysis, the char from CO2 pyrolysis was approximately 2% richer in carbon and this fact did not influence on the combustion properties of the char. The oil fraction was characterized mainly by acids with a maximum content of 68% at 600 °C in an argon atmosphere and the acid concentration depended on the carrier gas as follows line: Ar > N2 > CO2.

Characterization of top phase oil obtained from co-pyrolysis of sewage sludge and poplar sawdust

To research the impact of adding sawdust on top phase oil, a sewage sludge and poplar sawdust co-pyrolysis experiment was performed in a fixed bed. Gas chromatography (GC)/mass spectrometry (MS) was used to analyze the component distribution of top phase oil. Higher heating value, viscosity, water content, and pH of the top phase oil product were determined. The highest top phase oil yield (5.13 wt%) was obtained from the mixture containing 15% poplar sawdust, while the highest oil yield (16.51 wt%) was obtained from 20% poplar sawdust. Top phase oil collected from the 15% mixture also has the largest amount of aliphatics and the highest higher heating value (28.6 MJ/kg). Possible reaction pathways were proposed to explain the increase in the types of phenols present in the top phase oil as the proportion of poplar sawdust used in the mixture increased. It can be concluded that synergetic reactions occurred during co-pyrolysis of sewage sludge and poplar sawdust. The results indicate that the high ash content of the sewage sludge may be responsible for the characteristic change in the top phase oil obtained from the mixtures containing different proportions of sewage sludge and poplar sawdust. Consequently, co-pyrolysis of the mixture containing 15 % poplar sawdust can increase the yield and the higher heating value of top phase oil.