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Bioenergy generation from agricultural wastes and enrichment of end products 341

Particle density refers to the density of the individual particle but usually it is mea-
sured for a group of biomass particles. In a group the particle density is the total mass of
all particles divided by the volume of the total particles occupying without the pore space
volume.
Bulk density refers to the mass of the particles to the total volume it occupies includ-
ing the pore space volume. It plays an important role in the logistics work, that is, han-
dling, transportation, and storage of biomass particles. The bulk density also depends
upon the tapping whether it is loose fill or tight fill. Lam et al. (2007) measured the bulk
3
density of switchgrass from 50 to 264 and 68 to 325 kg/m for loose and packed fill,
respectively.
Grindability—Grindability of biomass refers to the resistance to grind and it is an energy
consuming process. Lignocellulosic materials are difficult to grind because of fibrous cel-
lulose and lignin. Till today, there is no standard test for grindability of biomass but
Hardgrove Grindability Index method is used for the grindability test. The disadvantage
of this process is that it requires particle size of the range 0.6 1.2 mm. An alternative,
Bond Work Index (BWI), was proposed by Williams et al. (2015) for grindability of bio-
mass. It is defined as the amount of energy required to reduce the infinite particle size to
80% passing 100 µm(Cai et al., 2017). Greater the BWI, more energy is required to grind
the material.
Flowability—Flowability describes the flow characteristics of biomass, that is, how it
flows from one point to other. It also plays an important role for the design and develop-
ment handling, transportation, and storage. The parameters that describe the flowability of
biomass are angle of repose, cohesion coefficient, compressibility index, and flow index
(Lumay et al., 2012).

15.3.2 Chemical properties
The chemical properties of biomass include its proximate analysis, ultimate analy-
sis, calorific value, and compositional analysis.

15.3.2.1 Proximate analysis

Proximate analysis describes the amount of moisture content, ash content, volatile
matter, and fixed carbon in the biomass sample.
Moisture content is the amount of water (internal and external) present in the
biomass sample and it is expressed as the percentage of weight. The presence of
moisture in the biomass affects the handling, storage, transportation, and the bio-
mass conversion efficiency. It is determined according to ASTM E1756-08 (2015).

The given sample is heated in a muffle furnace at a temperature of 105 C 6 2 C for

at least 3 h until we get the constant weight and then the amount of heated sample
is deducted from the raw sample to get the amount of moisture.
Ash content is one of the most important properties of biomass. It is the amount
left over residue after complete combustion of biomass. It is measured according to
the ASTM E17551-01 (2015) where dried biomass sample is completely combusted

in the muffle furnace in the temperature range of 575 C 6 10 C for 3 h. The per-

centage of ash content is calculated by diving the amount of ash to the amount of
raw biomass sample. Ash contains an enormous amount of inorganic elements,