Torrefaction - Biomass Gasification, Pyrolysis and Torrefaction - page 122

between torrefied pellet and raw wood pellet, we take this value to be
650 kg/m 3 . So, the volumetric density of energy of torrefied pellet, EV p,t ,
would be

m 3 m 3

EV p;t HHV t

3 ρ p 5

24 : 59 650 MJ = 15 : 98 GJ =

5 3 5

Raw
Wood

Torrefied
Wood

Wood
Pellet

Torrefied
Pellet

Volume energy density, MJ/m 3 3876 4512 8398 15,983

Mass energy density (as-received
basis), MJ/kg

12.92 24.59 19.28 24.59

c. Increase in energy density:

The volumetric energy density of raw wood was based on initial
value

3.12.
There is thus an increase of 312% of volumetric energy density of
biomass after torrefaction.
The increase in volumetric energy density due to pelletization
alone

5 (15,983 3876)/3876 5

5 (12,530 3876)/3876 5 2.23 or 223%.

4.7 TORREFACTION TECHNOLOGIES
A typical torrefaction plant would include several units like biomass han-
dling, preparation, dryer, torrefier, and product cooler. Among these, the tor-
refaction reactor is most important. Presently, vendors are offering many
designs of torrefier. This section presents a broad overview of those designs
of torrefier by classifying them under specific groups. Table 4.9 presents a

TABLE 4.9 Torrefaction Reactor Technologies Supplied by Different

Developers

Torrefier Technology Technology Supplier

Rotary drum reactor CDS(UK), Torr-coal (NL), BIO3D(FR), EBES AG(AT), 4Energy

Invest (BE), BioEndev/EPTS (SWE), Atmosclear S.A. (CH)

Screw conveyor BTG (NL), Biolake (NL),FoxCoal (NL), Agri-tech (US)

Multiple hearth CMI-NESA (BE), Wyssmont (US)

Entrained Topell (NL), Airex (Canada)

Fluidized Topell (NL)

Mircowave Rorowave (UK)

Source: Updated from Kleinschmidt ( www.kema.com ).