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62 Biomass Gasification, Pyrolysis and Torrefaction

2.5

2
Hemicellulose/Lignin 1.5

1

0.5

0
0 0.5 1 1.5 2 2.5 3 3.5 4
Cellulose/Lignin
Miscellaneous biomass Wood biomass Herbaceous biomass

FIGURE 3.11 Classification by constituent ratios of biomass. Source: Data from Jones et al.
(2006).

of a biomass during pyrolysis from the knowledge of these components (Jones
et al., 2006). Figure 3.11 plots the ratio of hemicellulose to lignin against the
ratio of cellulose to lignin. In spite of some scatter, certain proportionality can
be detected between the two. Biomass falling within these clusters behaves
similarly irrespective of its type. For a typical biomass, the cellulose lignin
ratio increases from ,0.5 to ,2.7, while the hemicellulose lignin ratio
increases from 0.5 to 2.0.

3.4.3 Ternary Diagram

The ternary diagram (Figure 3.12) is not a tool for biomass classification,
but it is useful for representing biomass conversion processes. The three cor-
ners of the triangle represent pure carbon, oxygen, and hydrogen—i.e., 100%
concentration. Points within the triangle represent ternary mixtures of these
three substances. The side opposite to a corner with a pure component (C, O,
or H) represents zero concentration of that component. For example, the
horizontal base in Figure 3.12 opposite to the hydrogen corner represents
zero hydrogen—i.e., binary mixtures of C and O.
A biomass fuel is closer to the hydrogen and oxygen corners compared to
coal. This means that biomass contains more hydrogen and more oxygen
than coal contains. Lignin would generally have lower oxygen and higher
carbon compared to cellulose or hemicellulose. Peat is in the biomass region
but toward the carbon corner, implying that it is like a high-carbon biomass.
Peat, incidentally, is the youngest fossil fuel formed from biomass.