Torrefied
Wood from Temperate & Tropical Species: Advantages & Prospects
J.P. BOURGEOIS and JACQUELINE DOAT
Abstract
This
paper gives the results obtained by the thermo-condensation of a few tropical
and temperate woods with
special reference to energetic yields and potential uses of this new product,
called "torrefied wood".
Upgrading of biomass by
means of torrefaction
Pentananunt, R. ,Rahman, A.N.M.M. and Bhattacharya, S.C.
Asian Institute of Technology, Bangkok, Thailand
Energy, Vol.15, No.12, pp.1175-1179 (1990)
Abstract
We present results on upgrading of wood and briquettes by means of
torrefaction. The torrefied products showed significantly less smoking during;
combustion and a relatively faster rate of combustion. The weight and energy
yields of torrefied wood are 66.7 to 83.3 and 76.5 to 89.6%, respectively: the
corresponding values for sawdust briquettes are 76.3 to 93.8 and 83.1 to 95.3%,
respectively.
Fuel wood is often difficult to use because of its poor combustion
characteristics, e.g., (low heating value, variable moisture content which is
often high, hydroscopic nature, smoking during combustion, etc. For
domestic and a number of other applications, wood is often upgraded to charcoal.
The charcoal-making process is, however, grossly inefficient, with the product
containing only about 55% of the energy of the original raw material in
well-managed, commercial operations and as little as 20% in traditional
processes.
Torrefaction or roasting appears to be an attractive option to upgrading wood to
a product which retains about 90% of its energy and can be substituted for
charcoal in a variety of applications. The important advantages of
torrefied wood include high energy yield and hydrophobicity so that it does not
regain moisture during storage.
Developments
on Torrefied Wood: An Alternative to Charcoal for Reducing Deforestation
Abstract
Prospects for torrefied wood, with its specific
properties and high-energy yield, are potentially very promising:
 | in industry, where its use as a reducer should
compare favorably with the use of charcoal, as the cost of low yields when compounded by high wood prices is reflected in rising charcoal production costs. |
| in the domestic fuel sector, where there is
evidence to show that torrefied wood may be more competitive than charcoal in developed countries and in the larger urban centers in arid zones where a correlative reduction in pressures on threatened woodland ecosystems would ensue. |
Bench unit for biomass
residues torrefaction
Fonseca Felfli, F, Luengo, C.A., Bezzon G. and Beaton Soler, P. (1998),
Abstract
A bench unit for biomass torrefaction was designed to improve energy properties
of agricultural and forest residues. In some applications, torrefied residues
may substitute firewood and charcoal, reducing costs and environmental impacts
during forest exploitation. The unit is composed basically by two chambers, one
for combustion and other one for thermal treatment. The combustion chamber
supplies thermal energy for the process, by burning biomass residues. Hot vapors
and gases produced in the torrefaction chamber are recirculated and burnt in the
combustion chamber, improving overall energy efficiency and avoiding atmospheric
pollution. Torrefied products of several experiments have presented low moisture
and hydrophobic nature. According to the process conditions and properties of
the starting material, the fixed carbon content of the products ranged from 25
to 40% and the overall yield from 70 to 90%. Also, the average calorific value
was near 23 MJ/kg, which is an intermediate value between biomass and charcoal.
Torrefied biomass presents good quality for combustion and gasification
purposes, with favorable characteristics for storage and transportation, mainly
because of its low moisture, high density and hydrophobic nature.
European
Community Demonstration projects for energy saving and alternative energy
sources.
Wood roasting unit: Aim
of the project
The
project consisted of building a wood roasting unit and demonstrating on an
industrial scale that the roasting process is technically and economically
viable. Roasted wood is obtained by subjecting wood to thermo-condensation
at a temperature of between 250 and 300° C. It is therefore an intermediate
product between wood and charcoal. It has most of the advantages of both
products.
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