Big problem, little answer: overcoming bed agglomeration and reactor slagging during the gasification of barley straw under continuous operation

Defluidisation as a result of reactor bed agglomeration is a global challenge associated with the gasification of lignocellulosic biomass waste, specifically its high inorganic content. The use of conventional water leaching has been scrutinised for the removal of inorganic constituents from barley straw, a highly abundant waste feedstock with a high ash content. The resulting pre-treated material was subsequently gasified at 750 °C and 850 °C under continuous flow, where it was found that bed agglomeration as a result of the ash melting induced mechanism can be eliminated, as visualised by SEM and EDX studies. Here, the presence of eutectic mixtures result in the fusing of a SiO2 rich bed material that causes a sudden pressure drop in the reactor, resulting in a forced shutdown. Leached barley straw was found to effectively solve this issue and sustained gasification for a long period of time, as well as limiting inorganic based decoration on the surface of bed material grains after reaction. Additionally, leaching was found to enhance the production of low carbon fuel gases where an improved product yield of 31.9 vol% and 37.3 vol% for CO and CH4 was observed at 850 °C, as compared to untreated equivalent.