Analytical Techniques - Biomass Gasification, Pyrolysis and Torrefaction - page 439

Chapter 13

Analytical Techniques

Feedstock analysis is a vital and important part of a process. It gives the crit-
ical information on biomass that is needed for a rational design or better
understanding of a process. This chapter discusses the methods used to deter-
mine the composition of biomass as a whole with specific reference to its
cell walls and its thermal and other properties. A typical wood comprises the
followings:

Wood Extractives Holocellulose Lignin Ash

5 1 1 1

Holocellulose 5 Hemicellulose 1 Cellulose
The analysis of biomass starts with reduction in the sample size from a
large representative one. Then a sequence of tests as below could be carried
out to determine different thermophysical properties of the biomass.

1. Ultimate analysis
2. Proximate analysis
a. Moisture content
b. Ash content
c. Volatile content
d. Fixed carbon
3. Extractive: polar (water) and nonpolar (organic)
4. Holocellulose
5. Hemicellulose
6. Lignin
7. Other analyses: chromatographic, spectroscopic, microscopic, and thermal
analysis.

The following sections present a brief description of some of the analyti-
cal processes.

13.1 COMPOSITION OF BIOMASS
13.1.1 Ultimate (Elemental) Analysis
Ultimate analysis gives the elemental composition of a fuel. Its determina-
tion is relatively difficult and expensive compared to proximate analysis.