The pyrolysis of coal and biomass present a level of similarity unusual among fields of research that are often considered as nominally distinct. Even so, much past research on coal and biomass pyrolysis has been conducted with relatively little reference to the many common aspects and shared challenges.  Characterizing the fundamental pyrolytic behavior of solid fuels requires a strict decoupling of observations on sample behavior from effects due to the design of the particular reactor and the shape and dimensions of the sample. What complicates the interpretation of pyrolysis data is challenges arising from the chemical reactivity of intermediate products released during thermal breakdown. Reactor related effects are magnified when lignocellulosic biomass is pyrolyzed, since most biomass materials and their evolving volatiles tend to be far more reactive than coals.<br/>Coal pyrolysis data from three bench scale pyrolysis reactors will be reviewed: a variable heating rate wire-mesh reactor, a flash-heating fluidized bed and a slow-heating fixed-bed (“hot-rod”) reactor. The trends will be contrasted with biomass pyrolysis data in similar reactors.  Two aspects of parallel observations on coal and biomass pyrolysis will be discussed. First, experiments show clear increases in volatile and tar yields with increasing heating rate during the pyrolysis of biomass samples – as with coals. The second involves transient plastic phases observed during the fast pyrolysis of <i>wood</i> and lignin samples. The second effect has rarely been considered in relation to the plastic behavior of rapidly heated biomass, still less studied in the context of the analogous knowledge base deriving from coal pyrolysis.

Thermal breakdown in coal and biomass: Relationship between reactor design and product distributions

256th National Meeting (2018)

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