BIOMASS COMPOSITION, PROPERTIES, AND CHARACTERIZATION - Biomass as a Sustainable Energy Source for the Future - page 60

Softening range Fluid/melting range

ASME

1/3r 1

r 1

2r 1

DIN

1/3r 2

r 2

2r 2

Spherical/
softening
temperature

Original
sample

Initial
deformation
temperature

Hemispherical
temperature

Fluid
temperature

FIGURE 2.10 Ash fusion characterization according to standards of DIN and ASME.
(Source: Reproduced with permission from Spliethoff (2009). © Springer.)

be observed through a visual inspection window in the furnace. The temperatures at
which characteristic changes of shape occur are recorded. The different characteristic
shapes are shown in Figure 2.10.
The following characteristic temperatures are defined:

￿ ID is the , the temperature at which the first

signs of shape changes are observed (edges and top).

“ initial deformation temperature ”

￿ ST is the , the temperature at which the top part exhibits a

spherically formed geometrywith a height equal to the width at the shape

“ softening temperature ”

' sbottom.

￿ HT is the , the temperature at which a hemisphere is

formed with a geometry that is characterized by a height that is equal to half of
the width.

“ hemispherical temperature ”

￿ FT is the , the final stage in which the ash is molten until an

extent at which the maximum height has been reduced to one third of the height
in the HT phase.

“ fluid temperature ”

The composition of the inorganic constituents in biomass and the ash composition in
terms of quantities of major elements are usually characterized using X-ray fluores-
cence (XRF) spectroscopy; the technique is described in, e.g., Beckhoff et al. (2006).
X-ray diffraction (XRD) can be used to identify which crystal structures are present in
a sample, thus enabling identification of species.
The main elemental composition of biomass (C, H, O) shows some variation, but
the composition of mineral matter is subject to a much larger variety. Vassilev et al.
(2010) have presented an overview of widely differing biomasses; in particular, the
variation in ash constituents is illustrative, as can be seen in Figure 2.11. The figure
is a triangular diagram showing on its axes the sums of acidic, high-temperature