Transcript Gas composition from biomass torrefaction – Preliminary

Gas composition from Biomass
Torrefaction
Linda Pommer1, Lorenz Gerber2, Susanne Wiklund Lindström1, Ingemar
Olofsson1, Anders Nordin1
1: Energy Technology and Thermal Process Chemistry, Umeå University, Sweden
2: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Sweden
Background
Torrefaction + pyrolysis-GC/MS
Biomass is a widespread source of renewable energy,
and has the potential to play a significant role in the
energy conversion decreasing the fossil fuel dependency.
However, a number of fuel characteristic properties could
be significantly improved.
Raw pulverized biomass samples were torrefied in a PyGC/MS. Two different heating rates were used; (1)
heating of the biomass to 300 ºC during 10 min, and (2)
heating to 300 ºC during 5 s.
Results
The composition of the products gas were determined
using both Py-GC/MS and MBMS. The compounds
present at the highest concentrations are presented in
the table below.
Figure 2. Weighs selected for analysis of separating
compounds between hardwood and softwood.
Identification of compounds in the product gas
separating hardwood from softwood
The knowledge of the composition of volatiles produced
in the temperature range of torrefaction is a topic of
interest for
 Producing “green chemicals”
 Energy process- and exergy optimization
 Process behavior and operation
 Raw material adaption process
 Process control
Objective
The objective with the present work was therefore to
determine the composition and the energy content of the
product gas from torrefaction utilizing different
biomasses.
Mass numbers selected from PLS-DA consisted mainly of
compounds derived from lignin. Compounds correlated to
hardwood were products derived from S-lignin and for
softwood from G-lignin.
Varying energy content
of torrefaction gas
Identification of main- and
separating compounds in
the torrefaction gas
Energy content of the product gas
Compounds in the product gas were tentatively identified
and quantified. The results are preliminary and indicate a
higher HHV (Higher Heating Value) for the product gas
during torrefaction of Birch. Differences in the contribution to the HHV from of specific compounds could be
attributable to dissimilarities of softwood and hardwood.
Multivariate analysis
Torrefaction + MBMS analysis
Chips from Birch, Pine and Spruce
were torrefied at 270-320 ºC. Initially
the wood chips were pre-dried in
105ºC over night before it was introduced into a heated alumina reactor
tube. The size of the wood chips
torrefied were 20 x 7 x 3 mm.
The wood chips were immersed
down through the reactor to stages
for initial drying (100ºC) and torrefaction (275-315 ºC). The biomass
was exposed to torrefaction conditions for 20-50 min. The produced
gases were continuously sampled by
a molecular beam mass spectrometer (MBMS).
All responses from MBMS measurements of the different
samples were used for both PCA and PLS-DA. In the
PLS-DA presented below the data was centered and UV
scaled for identification of to components correlated to
coniferous or deciduous wood independent on
concentrations.
Figure 3. Higher heating value of wet torrefaction product
gas.
Figure 1. PLS-DA separation of hardwood
Spruce) and softwood (Birch).
Figure 4. Relative contribution to higher heating value in
torrefaction product gas.
Zone 1
Zone 2
(Pine and
* Suggestion of compounds based on fragmentation and base peaks from the literature.
Energy Technology and
Thermal Process Chemistry
Umeå University
SE-901 87 Umeå, Sweden
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