main-content

## Weitere Artikel dieser Ausgabe durch Wischen aufrufen

01.12.2011 | Original Article | Ausgabe 4/2011 Open Access

# DDGS chars gasification with CO2: a kinetic study using TG analysis

Zeitschrift:
Biomass Conversion and Biorefinery > Ausgabe 4/2011
Autoren:
Xiangmei Meng, Wiebren de Jong, Ningjie Fu, Adrian H. M. Verkooijen

## 1 Introduction

Fossil fuels are non-renewable, and their massive utilization causes many environmental problems associated with CO2 emission. Biomass fuels are a potential source of alternatives to increase energy independence and reduce environmental pollution. Biomass can be converted into more valuable energy via either biochemical (fermentation, hydrolysis) or thermochemical conversion (pyrolysis, combustion, and gasification) technologies [1, 2]. Biomass gasification has received the highest interest since it offers high system efficiency and increases options for combination with various power generation systems using gas engines, gas turbines, and fuel cells [3]. Char gasification reactions like the Boudouard reaction (C + CO2 = 2CO) is the rate-limiting step during biomass gasification [4]. Therefore, a good understanding of char gasification kinetics is essential for the effective modeling and operation of gasification processes.
Dry Distiller’s Grains with Solubles (DDGS) is a non-fermentable byproduct of ethanol production. During the past decade, the global production of bioethanol increased from 17 billion liters in 2,000 to more than 46 billion liters in 2007, whereas in the USA alone, ethanol production increased from about 6.5 billion liters in 1999 to more than 39 billion liters in 2009 [5, 6]. The Renewable Fuels Association recently reported that the USA exported 397 million gallons of ethanol in 2010, which is nearly a 400% increase over 2009, and accompanied with the ethanol industry nine million metric tons of DDGS were also exported, which is a 60% increase over 2009 [7]. Driven by the mandate of the Renewable Fuels Standard II, ethanol and DDGS production will continue to grow until 2015 [8]. Currently, most of the DDGS is used primarily as a feed supplement and is an important product for the livestock and dairy industries. US Grains Council reported that the US domestic market demand for DDGS is becoming more and more saturated and needs to find potential for the export market to avoid the adverse effect on ethanol production [8]. Otherwise, as the supply for DDGS increases, ethanol plants must discount the price to persuade end-users to increase DDGS use for their cattle, swine, or poultry ratio. Therefore, the potential of DDGS for gasification to produce gaseous fuel has been investigated by Kumar et al. [1], Tavasoli et al. [9], and Meng et al. [10]. Liu et al. [11] studied the pyrolysis and oxidation kinetics of distiller’s grains and solubles (DGS) using thermogravimetric analysis (TGA). They reported that DGS residue had similar drying characteristics in both N2 and air. The determined activation energy (E a) of DGS during dry pyrolysis in N2 and oxidization in air were in the range of 18 to 36 and 10 to 60 kJ/mol. Giuntoli et al. [12] studied pyrolysis kinetics of DDGS and reported that DDGS mainly released NH3 and HCN with a minor release of HNCO which mainly came from proteins.
Gasification kinetics of various biomass chars with CO2 such as wood [13, 14], cotton wood [15], Douglas fir [15, 16], Eucalyptus wood [17], rice husk [18], olive residue [19], beech wood char and oil palm shell [20], olive husk and pine seed shells[21], and pine and birch [22] have been investigated. Various mathematical models like the random pore model (RPM), volumetric reaction model (VRM), and shrinking core model (SCM) as well as the Langmuir–Hinshelwood model (LHM) have been also applied in order to determine kinetic parameters. Bhat et al. [18] reported that VRM and SCM agreed well. Ollero et al. [19] reported that the LHM fitted well in the presence of CO. Lee and Kim [23] and Murillo et al. [24] studied gasification kinetics of waste tire char with CO2 using the SCM, VRM, and the modified VRM models. Matsumoto et al. [25] investigated gasification kinetics of four Japanese wood chars with CO2 using the RPM by considering surface porosity, constant particle size, and specific surface area. Seo et al. [26] reported that RPM predicted the experimental data better than the SCM and VRM. Fermoso et al. [27] reported that the LHM better fitted the reactivity data for char gasification at atmospheric and at elevated pressures. Kinetic parameters and gasification conditions of above-stated literature are summarized in Table 1, where it can be seen that there is a significant variation among kinetic parameters reported by different researchers depending on biomass fuel types, gasification conditions, and model types used.
Table 1
The kinetic parameters and gasification conditions presented in the literature
Reference Number
Char type
Kinetic model
Kinetic parameters
Gasification condition
E a (kJ/mol)
n
Temperature (°C)
Setup
Wood
A local volumetric rate model
217
0.6
800–1,100
Quarts container
Wood
SCM
210
0.71
900–1100
Tube furnace
Douglas Fir
VRM
220
0.6
700–900
Chamber furnace
Cottonwood
196
0.6
Douglas Fir
RPM
700–1100
PTGA
Eucalyptus wood
230–261
775–850
TGA
Rice husk grain
VRM
200
1
750–900
TGA
Rice husk power
VRM
197
1
Rice husk power
SCM
83
1
Olive residue
nth order model
133
0.43
800–950
TGA
Beech wood
LHM
200
720–730
TGA
Oil palm shell
300
730–780
Olive husk
nth order model
230
0.5
750–910
TGA
Pine seed shells
245
0.59
Wood chips
298
0.64
Pine and birch
nth order model
262–263
0.4
600–1000
TGA
Waste tire
The modified VRM
238
0.68
850–1000
Thermo-balance reactor
Waste tire
VRM
191.79
0.7
850–1000
Thermo-balance reactor
The modified VRM
191.40
0.5
SCM
197.45
1
RPM
197.70
1
Japanese wood
RPM
94
0.22
900–1200
drop tube furnace
Pinus densiflora for Multicaulis
VRM
172
850–1050
Fixed bed reactor
SCM
142
RPM
134
Pinus elliottii
VRM
184
0.33
750–900
PTGA
SCM
185
RPM
184
PTGA pressured TGA
Currently, only few data are available in the literature regarding gasification kinetics of DDGS char. In order to offer reliable kinetic data for the modeling DDGS gasification in a 100-kWth circulating fluidized bed (CFB) steam-O2 blown gasifier for syngas generation studies, the gasification reaction kinetics of DDGS chars with CO2 have been investigated using TGA. The aims of this work are to study the influences of pyrolysis temperatures, heating rates, gasification temperature, and CO2 concentrations on gasification kinetics of DDGS chars. As conversion models, VRM and SCM were applied to determine the kinetic parameters, since these two model can be easily coupled together with other reaction rates (e.g., homogenous reactions occurring during gasification) for further reactor modeling.

## 2 Experimental setup and char samples

### 2.1 Char samples preparation

A TA Instruments TGA Q600 apparatus has been employed to conduct all isothermal char gasification experiments. This apparatus is capable of providing a simultaneous measurement of heat flow and weight change on the same sample from ambient temperature (~20°C) to 1,500°C. A separate Inconel 600 tube permits introduction of reactive gases into the sample chamber [28]. DDGS used for this study was obtained from Lantmännen, Sweden. Two different types of char samples have been tested. Char type one (PYR-Char) was prepared under the following conditions: after the instrument was tarred to zero, around 20 mg ground DDGS was loaded into an alumina crucible, and then heated up using different heating rates (HR = 10°C/min, 30°C/min, 50°C/min, 70°C/min) and finally pyrolyzed at a temperature of 750°C or 850°C (T_Pyr = 750°C, 850°C) for 20 min in an N2 inert atmosphere. Char type two (CFB-Char) was obtained after DDGS gasification in the 100-kWth CFB steam-O2 blown gasifier within the temperature range of 790°C to 820°C with a steam/biomass mass ratio of 0.81 and oxygen to biomass stoichiometric ratio of approximately 0.38. The particle size distribution of the char samples was performed by using a Microtrac S3500 series particle size analyzer. The particle size distribution was determined as well as proper images of very small particles to be seen. It was found that around 30%, 50%, 70%, and 90% of the particles had a diameter below 0.13, 0.26, 0.5, and 0.9 mm, respectively. Some main properties of DDGS and char samples are listed in Table 2.
Table 2
DDGS and char sample properties
Types of fuel
Moisture (wt.% a.r.)
Volatile matters
Fixed carbon
Ash content
DDGS
12
67.2
15.5
4.82
CFB-Char
5–10
10–20
55–65
15–30

C
H
O
N
DDGS
48.2
6.54
31.2
5.52
CFB-Char
66.5
18.8

K2O
Na2O
MgO
CaO
DDGS-Ash
38.1
10
8.9
2.9

### 2.2 Char gasification procedures

A schematic diagram of the experiment setup is shown in Fig. 1. For PYR-Char, the experimental procedures used to perform char gasification in the TGA are as follows:
1.
Under N2 using a flow rate of ±100 ml/min supplied via a primary gas supply line, the temperature was equilibrated at 35°C for 20 min.

2.
In N2 atmosphere, heating from 35°C to 750°C or 850°C at a constant rate of 10°C/min, 30°C/min, 50°C/min, or 70°C/min

3.
Isothermal at 750°C or 850°C for 20 min to ensure that the sample was completely pyrolyzed

4.
Introduction of pure CO2 via a second gas supply line which was further mixed with N2 from primary gas supply line to achieve different CO2 concentrations (CO2 = 10, 20, or 30 vol.%) and rapidly heated up to the desired gasification temperatures (T_Ga = 900°C, 1,000°C, or 1,100°C)

5.
Isothermal temperature at 900°C, 1,000°C, or 1,100°C for 20 min for char gasification

Since DDGS CFB-Char was released from the devolatilization and gasification process during DDGS gasification in the CFB gasifier to simulate this rapid heating up environment, a different temperature program has been applied to DDGS CFB-Char. After around 10 mg char sample was loaded into an alumina crucible, the temperature was increased from ambient temperature (~20°C) to 850°C as fast as possible (around 4 min) under N2 of a flow rate of ±100 ml/min and then the isothermal at a temperature of 850°C for 20 min to ensure that residual volatiles were completely released. The following steps were kept the same as PYR-Char (steps 4–5).

### 2.3 Kinetic models of data analysis

The VRM and SCM models were applied to DDGS char gasification with CO2 to determine Arrhenius kinetic parameters. The VRM assumes that the char particle reacts homogeneously with CO2 and that the particle size remains constant while the density decreases during the reaction [24]. The SCM assumes that the reaction initially occurs at the external surface of char and gradually CO2 diffuses through the gas film and the ash layer and reacts on the unreacted core surface, which keeps on shrinking but always exists during the reaction progress [18, 23]. The overall reaction rates for VRM and SCM are expressed in Eqs. 1 and 2, where X, K VRM and K SCM, n, and $${C_{{{\text{C}}{{\text{O}}_{{2}}}}}}$$ represent char reaction ratio (−), the reaction rate constant of VRM and SCM, the reaction order (−), and concentration of CO2 (vol.%), respectively. K VRM/K SCM and X were calculated using Eqs. 3 and 4, where k 0, E a, R g, and T represents the pre-exponential factor (s−1), the activation energy (J/mol), universal gas constant (8.314 J/(mol·K)) and reaction temperature (K), and m 0, m t, and m f represent the initial char weight, the char weight at time t, and the residue char weight, respectively.
$$\frac{{{\text{d}}X}}{{{\text{d}}t}} = {K_{\text{VRM}}}\left( {1 - X} \right){C_{{{\text{C}}{{\text{O}}_{{2}}}}}}^n$$
(1)
$$\frac{{{\text{d}}X}}{{{\text{d}}t}} = 3{K_{\text{SCM}}}{\left( {1 - X} \right)^{{ \frac{2}{3} }}}{C_{{{\text{C}}{{\text{O}}_{{2}}}}}}^n$$
(2)
$${K_{\text{VRM}}}({\text{or }}{K_{\text{SCM}}}) = {k_0}\exp (\frac{{ - {E_{\text{a}}}}}{{{R_{\text{g}}}T}})$$
(3)
$$X = \frac{{{m_0} - {m_t}}}{{{m_0} - {m_{\text{f}}}}}$$
(4)

## 3 Results and discussion

### 3.1 Effects of different parameters on conversion rate

Figure 2 shows the PYR-Char conversion rate versus time curves at different heating rates (10°C/min, 30°C/min, 50°C/min, 70°C/min) at two fixed gasification temperatures (900°C, 1,100°C) with 10 vol.% CO2. It can be seen that a higher heating rate during pyrolysis generally enhanced PYR-Char conversion rate. When the heating rate was increased from 10°C/min to 70°C/min, the conversion rate of PYR-Char at 900°C within 20 min increased from 50% to 85%. These observations agreed with those obtained from willow PYR-Char [29]. However, an increase in the heating rate from 10°C/min to 30°C/min almost did not affect the conversion rate neither at 900°C nor at 1,100°C. From this, it can be seen that under similar conditions, DDGS PYR-Char was less reactive than willow PYR-Char, and also, its char reactivity was less affected by low range heating rate change.
Figure 3 shows the PYR-Char conversion rate versus time curves at different pyrolysis temperatures (750°C, 850°C) at two fixed heating rates (10°C/min, 70°C/min) with 10 vol.% CO2. It can be seen that PYR-Char obtained at the pyrolysis temperature of 750°C was slightly more reactive than chars obtained at 850°C. However, the influence of pyrolysis temperature on the conversion rate became negligible for PYR-Char obtained at 70°C/min and further gasified at 1,100°C. From this observation, it can be derived that the char reactivity can be enhanced by lowering pyrolysis temperature or increasing heating rate.
Figure 4 shows the PYR-Char conversion rate versus time curves at different CO2 concentrations (10, 20, and 30 vol.%) and different gasification temperatures (900°C, 1,000°C, 1,100°C) of a heating rate of 10°C/min. It can be seen that gasification temperature significantly affected PYR-Char conversion rate. No PYR-Char samples completely reacted at 900°C, but all PYR-Char samples reacted completely at 1,100°C even with 10vol.% CO2. With 10vol.% CO2, the PYR-Char conversion rate increased sharply from 50% to 100% with increasing temperature from 900°C to 1,100°C. Higher CO2 concentration increased all PYR-Char conversion rate. When the CO2 concentration was increased from 10 to 30 vol.%, the PYR-Char conversion rate gasified at 900°C increased sharply from 50% to more than 90%. Furthermore, from Fig. 4, it can be clearly seen that with higher CO2 concentrations at higher temperature, DDGS PYR-Char firstly reacted very fast then slowed down, probably due to an increase of the ratio of ash to unreacted char sample. This observation was not found during willow PYR-Char gasification [29].
The gasification temperature and CO2 concentration had a similar influence on DDGS CFB-Char which can be seen in Fig. 5. CFB-Char was more reactive at lower temperature than PYR-Char and completely reacted under all reaction conditions. Scanning electron microscopy (SEM) photographs of PYR-Char obtained from pyrolysis temperature of 850°C with heating rate of 10°C/min and 70°C/min and CFB-Char are shown in Fig. 6. It can be seen that PYR-Char obtained at 10°C/min was less porous, while such char obtained at 70°C/min had some condensation on the surface and DDGS CFB-Char was very fragile and also observed condensation on char surface.
There were no results available in the literature to compare the results obtained from this work. Since DDGS is one kind of agriculture residue, its char gasification behavior can be explained by the results obtained from biomass derived char gasification. According to Di Blasi [4], the char conversion rate is critically determined by several fundamental factors, represented by surface area, surface accessibility, carbon active sites, and catalytic active sites created by indigenous or added inorganic matter and the local gaseous reactant concentration. Therefore, an enhancement in the char conversion rate is ultimately due to an improvement of these factors. Standish and Tanjung [14] reported that incomplete char reaction at lower CO2 concentration was due to possible reduction of active site density by available N2 high concentration around. Fermoso et al. [27], Ashu et al. [30], Kumar and Gupta [31, 32], and Lu et al. [33] reported that an increase in pyrolysis temperature substantially decreased the char reactivity because char structures such as amorphous concentration, aromaticity, and crystallite size became more ordered at higher temperatures thus lowering the concentration of reaction sites. Okumura et al. [16], Chen et al. [34], Cetin et al. [35], Guerrero et al. [36], Kurosaki et al. [37], and Mermoud et al. [38] reported that char obtained at high heating rate possessed higher reactivity than chars obtained at low heating rate, which is because chars obtained at high heating rate during pyrolysis generally had sparse, large internal cavities, and macropores structure and/or a higher concentration of active sites. Fushimi et al. [39] reported that the increase in the maximum rate of weight loss and volatile yield observed at high heating rate during pyrolysis also shortened tar vapors residence time in the pores, thus reducing the activity of condensation reactions and preventing char agglomeration and condensation of fragments on the char surface. Furthermore, DDGS ash is rich in alkali (K and Na) and alkaline earth (Ca and Mg), which are the most commonly used catalysts; thus, these elements present in char samples could also affect char reactivity under different cases [40].

### 3.2 External and internal mass transfer limitation

According to Di Blasi [4], both the mass and heat transfer effects could become more prominent at higher temperatures and higher reactant partial pressure. In this paper, several criteria were applied in order to estimate effects of mass and heat during char gasification. Mears criterion [41] was used to estimate effects of external mass transfer (Eq. 5) and intraphase heat transfer (Eq. 7). Weisz–Pater criterion [42] was used to determine effect of internal mass transfer (Eq. 6). When Eqs. 57 are satisfied, it means that effects of external mass transfer, internal mass transfer, and intraphase heat transfer effects can be neglected.
$${k_{\text{ex}}} = \frac{{ - r_{\text{A}}^{'}{\rho_{\text{c}}}\left( {1 - \varepsilon } \right){R_{\text{p}}}n}}{{{k_{\text{g}}}{C_{\text{Ab}}}}} < 0.15$$
(5)
$${C_{\text{wp}}} = \eta {\phi_{{1}}}^2 = {3}\left( {{\phi_{{1}}}\coth {\phi_{{1}}} - 1} \right) < < 1$$
(6)
$${k_{\text{heat}}} = \left| {\frac{{ - \Delta {H_{\text{RX}}}\left( { - r_{\text{A}}^{'}} \right){\rho_{\text{c}}}\left( {1 - \varepsilon } \right){R_{\text{p}}}{E_{\text{a}}}}}{{h{T^2}{R_{\text{g}}}}}} \right| < 0.15$$
(7)
$${\phi_n} = {R_{\text{p}}}\sqrt {{\frac{{{k_n}{\rho_{\text{c}}}{S_{\text{a}}}C_{\text{As}}^{{n - 1}}}}{{{D_{\text{e}}}}}}}$$
(8)
Where
Items
Meanings
Reference
C Ab
Bulk fluid gas concentration (kmol/m3)
This work
C AS
Surface fluid gas concentration (kmol/m3)
This work
D e
Effective diffusivity (m2/s)
Calculated [42, 43]
d p
Solid particle diameter (m), d p = 2R p
This work
h
Heat transfer coefficient, (kJ/m2·s·K)
This work
k g
Mass transfer coefficient (m/s)
This work
k n
n-order specific reaction rate constant ($${\left( {{{{{{\text{m}}^{{\text{3}}}}}} \left/ {{{\text{kmol}}}} \right.}} \right)^{{n - {\text{1}}}}} \times \left( {{\text{m}} \times {{\text{s}}^{{ - {\text{1}}}}}} \right)$$)
This work
n
Reaction order
This work
$$r_{\text{A}}^{'}$$
Reaction rate per unit mass of solid particle (kmol/kg-solid·s)
This work
R p
This work
S a
Surface area of the solid particle (m2/kg)
This work
ρ c
Density of the solid particle (kg/m3)
This work
ε
Bed porosity (−)
This work
H RX
Heat of reaction (kJ/kmol)
[44]
n
Thiele modulus (−)
This work
η
Internal effectiveness factor (−)
This work
From Eqs. 5 to 8, it can be seen that many parameters are required in order to determine mass and heat transfer limitations. Among them, effective diffusivity (D e) was calculated using gases molecular diffusivity (D AB) and Knudsen diffusivity (D KA). Mass transfer coefficient (Kg) was calculated based on estimation of Reynolds (Re) number and Sherwood (Sh) number. Most parameters were measured and calculated from experimental data, while some parameters ∆H RX, D AB, and D KA were obtained from different literatures [4244]. One type of PYR-Char (DH70_T850_T1100_0.3) and one type of CFB char (CFB D_T1100_0.3), which showed the highest reaction rate were chosen for calculation. DH70_T850_T1100_0.3 means PYR-Char obtained at pyrolysis temperature 850°C, heating rate 70°C/min and further gasified at 1100°C with 30 vol.% CO2 and CFB D_T1100_0.3 means CFB-Char pyrolyzed at 850°C and further gasified at 1,100°C with 30 vol.% CO2. The final calculation results are shown in Table 3. From Table 3, it can be seen that effects of mass and heat transfer both can be neglected during PYR-Char and CFB-Char gasification.
Table 3
The calculated values for estimating possible limitation effects of mass and heat transfer

PYR-Char (VRM)
PYR-Char (SCM)
CFB-Char (VRM)
CFB-Char (SCM)
C wp
9.25E-03
6.81E-03
6.64E-03
4.98E-03
k ex
9.01E-03
4.89E-03
4.65E-03
2.61E-03
k heat
2.61E-05
1.37E-05
8.67E-06
4.74E-06

### 3.3 Determination of conversion kinetics

Figures 7 and 8 show the plots of −ln(1 − X) and 1 − (1 − X)1/3 versus time for PYR-Char at different temperatures and CO2 concentrations, respectively. It can be seen that generally, the conversion rates of PYR-Char present a linear correlation with time at different gasification temperatures and different CO2 concentrations. Figures 9 and 10 show the calculated E a values for PYR-Char and CFB-Char. From these two figures, it can be seen that for almost experimental conditions, the calculated E a value using the SCM was slightly lower than that using VRM and increased sharply with increasing CO2 concentration. The calculated E a values for PYR-Char using SCM and VRM were both in the range of 100–165 kJ/mol, while the calculated E a values for CFB-Char were in the range of 55–100 kJ/mol, which were in the comparable E a value ranges obtained from willow char samples [29] and the results reported by other researchers [18, 25, 26]. From Fig. 9, it can be seen that an increase in the heating rate did not significantly affect the E a values of PYR-Char. CFB-Char showed much lower E a values than PYR-Char under all conditions. From Fig. 10, it can be seen that the averaged E a values of PYR-Char obtained at pyrolysis temperature of 750°C were slightly lower than those obtained at pyrolysis temperature 850°C. However, fairly high E a values were observed for all PYR-Char obtained at a heating rate of 30°C/min and gasified with 20 vol.% CO2. CO2 concentration significantly affected E a values of all char samples and E a values increased with increasing CO2 concentration. According to Di Blasi [4], the E a values for CO2 gasification generally varied between 88 and 250 kJ/mol. In this way, DDGS CFB-Char had fairly low E a values when they were gasified with low CO2 concentration. The influences of different factors (e.g., pyrolysis temperature, heating rate, etc.) on E a have been discussed also by other researchers. According to Kumar and Gupta [31, 32], the E a values obtained during wood char CO2 gasification increased with increasing pyrolysis temperature and/or decreasing heating rate.

### 3.4 Recalculated TG

The weight loss (TG) curve was recalculated using the calculated Arrhenius parameters and compared with experimental ones to verify the models. Figure 11 shows the recalculated weight loss for PYR-Char at different CO2 concentrations, where PYR-Char was obtained at pyrolysis temperature of 850°C, heat rate of 10°C/min, and gasified at 900°C. Figure 12 shows the recalculated weight loss for CFB-Char at different CO2 concentrations, where CFB-Char was obtained at pyrolysis temperature of 850°C and gasified at 1,100°C. From these two figures, it can be seen that the calculated TG values for all char samples showed a fairly good fitting with the experimental results. At low gasification temperature of 900°C, almost no differences were observed between the predicted values from VRM and SCM models. However, at high gasification temperature of 1,100°C, SCM seemed to be more suitable than VRM model. From above observations, it was confirmed that VRM and SCM were suitable here to determine kinetic parameters of char gasification. However, since effects of mass and heat transfer could be enhanced with increasing temperature, for char gasification at high temperature with high reactant partial pressure, their effects need to be checked before applying the conversion models.

## 4 Conclusion

Gasification kinetics of DDGS PYR-Char and CFB-Char with CO2 was investigated using a TGA. It was found that char reaction rate increased with increasing gasification temperature, CO2 concentration, and heating rate but decreased with increasing pyrolysis temperature. Generally, the calculated E a values using SCM were slightly lower than those using VRM. The calculated E a values for PYR-Char using both models were in the range of 100–165 kJ/mol, while the calculated E a values for CFB-Char were in the range of 55–100 kJ/mol. The predicted results using both models showed a good agreement with experimental results in particular with those obtained at lower gasification temperature and lower CO2 concentration. According to observation from SEM, CFB-Char was more fragile, while PYR-Char obtained at lower heating rate had a less porous structure.

## Acknowledgements

The authors thank Lantmännen for supplying the DDGS fuel, Michael Müller from Institute of Energy Research, Forschungszentrum Jülich GmbH for performing fuel characterization analysis, and Michel van den Brink from Process and Energy TU Delft for performing SEM analysis. The European Commission is acknowledged for co-financing 7th Framework Project, related to this research: Integrated Project “GreenSyngas” (Project NO. 213628).

### Open Access

Open AccessThis is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://​creativecommons.​org/​licenses/​by-nc/​2.​0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

## Unsere Produktempfehlungen

### Springer Professional "Wirtschaft+Technik"

Online-Abonnement

Mit Springer Professional "Wirtschaft+Technik" erhalten Sie Zugriff auf:

• über 69.000 Bücher
• über 500 Zeitschriften

aus folgenden Fachgebieten:

• Automobil + Motoren
• Bauwesen + Immobilien
• Elektrotechnik + Elektronik
• Energie + Umwelt
• Finance + Banking
• Management + Führung
• Marketing + Vertrieb
• Maschinenbau + Werkstoffe
• Versicherung + Risiko

Testen Sie jetzt 30 Tage kostenlos.

### Springer Professional "Technik"

Online-Abonnement

Mit Springer Professional "Technik" erhalten Sie Zugriff auf:

• über 50.000 Bücher
• über 380 Zeitschriften

aus folgenden Fachgebieten:

• Automobil + Motoren
• Bauwesen + Immobilien
• Elektrotechnik + Elektronik
• Energie + Umwelt
• Maschinenbau + Werkstoffe​​​​​​​

Testen Sie jetzt 30 Tage kostenlos.

### Premium-Abo der Gesellschaft für Informatik

Sie erhalten uneingeschränkten Vollzugriff auf alle acht Fachgebiete von Springer Professional und damit auf über 45.000 Fachbücher und ca. 300 Fachzeitschriften.

Literatur
Über diesen Artikel

Zur Ausgabe