Page 88 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

66 Biomass Gasification, Pyrolysis and Torrefaction

TABLE 3.6 Standard Methods for Biomass Compositional Analysis
Biomass Constituent Standard Methods
Carbon ASTM E 777 for RDF
Hydrogen ASTM E 777 for RDF
Nitrogen ASTM E 778 for RDF
Oxygen By difference
Ash ASTM D 1102 for wood, E 1755 for biomass, D 3174
for coal
Moisture ASTM E 871 for wood, E 949 for RDF, D 3173 for coal
Hemicelluloses TAPPI T 223 for wood pulp
Lignin TAPPI T222 for wood pulp, ASTM D 1106, acid
insoluble in wood
Cellulose TAPPI T 203 for wood pulp

dropped from a height of 150 mm three times for settlement and refilling.
The final weight of the biomass in the box divided by the box volume gives
its bulk density.
The total mass of the biomass may contain the green moisture of a liv-
ing plant, external moisture collected in storage, and moisture inherent
in the biomass. Once the biomass is dried in a standard oven, its mass
reduces. Thus, the density can be based on either green or oven-dry
depending on if its weight includes surface moisture. The external mois-
ture depends on the degree of wetness of the received biomass. To avoid
this issue, we can completely saturate the biomass in deionized water,
measure its maximum moisture density, and specify its bulk density
accordingly.
Three of the preceding densities of biomass are related as follows:
ρ 5 ρ (3.7)
apparent true ð1 2 ε p Þ
ρ bulk 5 ρ apparent ð1 2 ε b Þ (3.8)

where ε p is the void fraction (voidage) in a biomass particle and ε b is the
voidage of particle packing.

Biomass (Growth) Density
The term biomass (growth) density is used in bioresource industries to
express how much biomass is available per unit area of land. It is defined as