Combustion and fuel characterisation of wheat distillers dried grain with solubles
(DDGS) and possible combustion applications
, Alejandro Grimm
, Nils Skoglund
, Dan Boström
, Marcus Öhman
Swedish University of Agricultural Sciences, Department of Forest Resource Management, S-901 83 Umeå, Sweden
Energy Engineering, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden
Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umeå University, SE-901 87 Umeå, Sweden
Fuel properties of residues from wheat-based ethanol production were determined.
Fluidized bed, grate and powder combustion, and ash characterisation.
Powder combustion produced K- and P-rich ﬁne particles, with risks of fouling.
The slagging and bed agglomeration tendencies were high.
Mixtures with Ca-rich logging residues reduced these tendencies considerably.
Received 19 January 2011
Received in revised form 9 November 2011
Accepted 9 May 2012
Available online 23 May 2012
The present transition to a sustainable global energy system requires that biomass is increasingly com-
busted for heat and power production. Agricultural fuels considered include alkali-rich fuels with high
phosphorus content. One such fuel is wheat distiller’s dried grain with solubles (wheat DDGS) from
wheat-based ethanol production. Further increases in ethanol production may saturate the current market
for wheat DDGS as livestock feed, and fuel uses are therefore considered. Fuel properties of wheat DDGS
have been determined. The ash content (5.4 ± 1.6 %
) is similar to many agricultural fuels. In compar-
ison to most other biomass fuels the sulphur content is high (0.538 ± 0.232 %
), and so are the contents
of nitrogen (5.1 ± 0.6 %
), phosphorus (0.960
± 0.073 %
) and potassium (1.30 ± 0.35 %
determine fuel-speciﬁc combustion properties, wheat DDGS and mixes between wheat DDGS and logging
residues (LR 60 %
and DDGS 40 %
), and wheat straw (wheat straw 50 %
, DDGS 50 %
pelletized and combusted in a bubbling ﬂuidised bed combustor (5 kW) and in a pellets burner combustor
(20 kW). Pure wheat DDGS powder was also combusted in a powder burner (150 kW). Wheat DDGS had a
high bed agglomeration and slagging tendency compared to other biomass fuels, although these tenden-
cies were signiﬁcantly lower for the mixture with the Ca-rich LR, probably reﬂecting the higher ﬁrst melt-
ing temperatures of K–Ca/Mg-phosphates compared to K-phosphates. Combustion and co-combustion of
wheat DDGS resulted in relatively large emissions of ﬁne particles (<1
m) for all combustion appliances.
For powder combustion PM
was sixteen times higher than from softwood stem wood. While the Cl con-
centrations of the ﬁne particles from the the mixture of LR and wheat DDGS in ﬂuidised bed combustion
were lower than from combustion of pure LR, the Cl- and P-concentrations were considerably higher from
the wheat DDGS mixtures combusted in the other appliances at higher fuel particle temperature. The par-
ticles from powder combustion of wheat DDGS contained mainly K, P, Cl, Na and S, and as KPO
main phase identiﬁed with XRD) is known to have a low melting temperature, this suggests that powder
combustion of wheat DDGS should be used with caution. The high slagging and bed agglomeration ten-
dency of wheat DDGS, and the high emissions of ﬁne particles rich in K, P and Cl from combustion at high
temperature, mean that it is best used mixed with other fuels, preferably with high Ca and Mg contents,
and in equipment where fuel particle temperatures during combustion are moderate, i.e. ﬂuidised beds
and possibly grate combustors rather than powder combustors.
Ó 2012 Elsevier Ltd. All rights reserved.
0016-2361/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
Corresponding author at: Swedish University of Agricultural Sciences, Department of Forest Resource Management, S-901 83 Umeå, Sweden. Tel.: +46 90 786 84 29,
mobile: +46 70 21 97 432; fax: +46 90 778 116.
E-mail address: Gunnar.Eriksson@srh.slu.se (G. Eriksson).
Fuel 102 (2012) 208–220
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