In-situ release characteristic of alkali metals during co-pyrolysis of coal and biomass in a visual fixed bed combined with laser-induced breakdown spectroscopy

In this article, a visual fixed bed (VFB) combined with laser-induced breakdown spectroscopy (LIBS) was innovatively applied to investigate the in-situ release characteristics of alkali metals during fast co-pyrolysis of coal and biomass. The concentration of released alkali metals in gas phase was measured and used to reflect their temporal release behavior. The results showed that the release of alkali metals first increased and then decreased over time. The pyrolysis temperature, mass ratio of biomass to coal, and minerals in coal had little effect on the temporal release trends but seriously affected the release concentration extremity of alkali metals. Moreover, the interaction between coal and biomass caused the less release of alkali metals during the co-pyrolysis than biomass pyrolysis. This study benefited the better understanding on the release of alkali metals and the further industrial application of coal and biomass co-pyrolysis.