Centro Nacional de Pesquisa em Energia e Materiais
Laboratório Nacional de Ciência e Tecnologia do Bioetanol
MeT 22/2015
SUGARCANE BIOMASS COMPOSITION
FOR THE INDUSTRIAL SIMULATIONS IN THE
VIRTUAL SUGARCANE BIOREFINERY (VSB)
Tassia Junqueira
Vera Gouveia
Isabelle Sampaio
Edvaldo Morais
Antonio Bonomi
O CTBE integra o CNPEM, Organização Social qualificada pelo Ministério da Ciência, Tecnologia e Inovação (MCTI)
Campus: Rua Giuseppe Máximo Scolfaro, 10.000 - Polo II de Alta Tecnologia - Caixa Postal 6192 - 13083-970 - Campinas/SP
Fone: +55.19.3512.1010 | Fax: +55.19.3518.3164 | www.bioetanol.org.br
ABSTRACT
The simulation of an industrial process, within the Virtual Sugarcane Biorefinery
platform, is based on mass and energy balances carried out through process
simulators, such as Aspen Plus, SuperPro and EMSO. Regardless of the
simulation environment, the definition of feedstock composition is one of the
first steps for process simulation.
In this technical memorandum, the basis for establishment of the composition
of sugarcane biomass (stalks, bagasse and straw) is documented, including
the consulted references and assumptions.
Keywords: sugarcane; stalks; bagasse; straw; composition.
2
SUMMARY
1
INTRODUCTION ............................................................................. 4
2
REVIEW OF COMPOSITIONS FOR SUGARCANE BIOMASS ..... 5
2.1
Sugarcane stalks ........................................................................ 5
2.2
Sugarcane bagasse.................................................................... 7
2.3
Sugarcane straw......................................................................... 9
3
ADOPTED COMPOSITIONS FOR SUGARCANE BIOMASS IN
THE VSB ............................................................................................. 10
3.1
Sugarcane stalks composition in the VSB ............................. 10
3.2
Sugarcane bagasse composition in the VSB ........................ 11
3.3
Sugarcane straw composition in the VSB ............................. 12
4
FINAL REMARKS ......................................................................... 12
REFERENCES .................................................................................... 13
3
1 Introduction
The Virtual Sugarcane Biorefinery (VSB) is an innovative framework that
integrates computer simulation platforms with economic, social and
environmental evaluation tools to assess technical and sustainability impacts
of different sugarcane biorefinery alternatives/routes integrating all the stages
of the biomass chain: agricultural production, transport, industrial conversion,
use and final disposal of the products.
The definition of feedstock composition is one of the requisites for process
simulation. In a sugarcane biorefinery, stalks, straw and bagasse represent the
main feedstock alternatives for production of ethanol, energy and other
renewable products.
In the sugarcane plant, stalks contain most of the sugars, while straw (or trash)
consists of tops and leaves, as represented in Figure 1. Bagasse is the fibrous
residue obtained after sugars extraction in the sugarcane processing.
This technical memorandum presents the basic premises for definition of
sugarcane biomass composition for the industrial simulations in the VSB
framework, based on compositions gathered from literature.
Figure 1. Sugarcane plant parts (HASSUANI et al., 2005).
4
2 Review of compositions for sugarcane biomass
This section presents a collection of literature compositions for sugarcane
biomass (stalks, bagasse and straw) that supported the establishment of the
composition considered in the VSB simulations.
2.1
Sugarcane stalks
Sugarcane quality varies considerably according to time of planting, type of soil,
climate conditions, etc. Some examples for sugarcane stalks composition,
including ranges for the main components, are shown in Tables 1 to 4.
Table 1. Sugarcane stalks composition (HIGA, 1999).
Component
Content (wt%)
Water
65 -75
Sugars
11-18
Soluble solids
12-23
Fibers
8-14
Table 2. Sugarcane stalks composition and breakdown of soluble solids
(COPERSUCAR, 2010).
Component
Content (wt%)
Water
65 a 75
Sugars
11 a 18
Fibers
8 a 14
Soluble solids
12 a 23
Breakdown of soluble solids (wt%)
Sugars
75 a 93
Sucrose
70 a 91
Glucose
2a4
Fructose
2a4
Salts
3a5
Inorganic salts
1.5 a 4.5
Organic salts
1a3
Proteins
0.5 a 0.6
Starch
0.001 a 0.05
Gums
0.3 a 0.6
Fats and waxes
0.05 a 0.15
Pigments
3a5
5
Table 3. Average composition and ranges for sugarcane stalks (CAMARGO, 1990).
Component
Average (wt%)
Lower limit (wt%)
Upper limit (wt%)
Water
74.50
65
75
Sugars
14.00
12
18
- Sucrose
12.50
11
18
- Glucose
0.90
0.2
1
- Fructose
0.60
0
0.6
Fibers
10.00
8
14
- Cellulose
5.50
- Lignin
2.00
- Hemicellulose
2.00
- Gums
0.50
Ash
0.50
0.4
0.8
- SiO2
0.25
- K2O
0.12
- P2O5
0.07
- CaO
0.02
- SO3
0.02
- Na2O
0.01
- MgO
0.01
- Cl
Trace
- Fe2O3
Trace
Nitrogen compounds
0.4
0.3
0.6
- Amino acids (aspartic
acid)
0.2
- Albuminoids
0.12
- Amides (asparagine)
0.07
- Nitric acid
0.01
- Ammonium
Trace
Fats and waxes
0.20
0.15
0.25
Gums and others
0.20
0.15
0.25
Other acids
0.12
0.1
0.15
Free acids
0.80
0.06
0.1
6
Table 4. Average fibers and sucrose (Pol) content (mass basis) in sugarcane stalks
reported in the literature.
Fiber content (wt %)
Pol (%)
Reference
14.0
14.0
Ensinas et al. (2007); Ensinas (2008)
13.0
14.5
Seabra (2008)
12.9
14.0
Leal (2005)
12.7
14.2
Finguerut (2006); Macedo et al. (2008)
13.2
14.0
Pedra Sugar Mill (2006)*
* Reducing sugars = 0.62 wt%.
2.2
Sugarcane bagasse
In Tables 5 to 10, compositions for sugarcane bagasse found in the literature
are presented, including different fractions and source region.
Table 5. Composition for sugarcane bagasse, fibers and pith fraction (ICIDCA, 1999
apud CGEE, 2009).
Content (wt%, dry basis)
Bagasse
Fibers
Pith
Cellulose
46.6
47.7
41.2
Hemicellulose
25.2
25.0
26.0
Lignin
20.7
19.5
21.7
Organic solubles
2-3
Water solubles
2-3
Ashes
2-3
Moisture
48 - 52
Table 6. Composition for sugarcane bagasse for different regions (MACHADO, 2000).
Cellulose
Hemicellulose
Lignin
Ashes
Region
58.4
29.4
21.3
2.9
EUA (Louisiana)
56.8
31.8
22.3
2.3
Philippines
50.9
29.6
18.1
3.9
Porto Rico
45.3
24.1
22.1
1.6
South Africa
ND
19.4 a 21.6
27.6 a 28.4
1.3 a 2.0
Hawaii
46.6
25.2
20.7
2.6
Cuba
49.1
27.8
20.3
1.6
Brazil (São Paulo)
7
Table 7. Composition for sugarcane bagasse (SEABRA et al., 2010).
Component
Content (wt%, dry
basis)
Cellulose
39.5
Hemicellulose
21.9
Lignin
25.1
Extractives
2.2
Ashes
4.6
Other components
6.7
Moisture (wt%)
50
Table 8. Composition for not screened and screened bagasse (RABELO, 2007).
Component
Not screened (wt%)
Screened (wt%)
Extractives
0.6±0.3
2.3±0.1
Ashes
3.8±0.1
5.3±0.1
Lignin
25.8±0.2
29.3±1.6
Cellulose
39.6±1.6
34.1±0.9
Hemicellulose
19.7±0.6
17.7±0.5
Acetyl groups
2.5±0.2
2.4±0.1
Table 9. Mass composition (wt%) of sugarcane bagasse from different references.
Cellulose
Hemicellulose
Lignin
Ashes
Extractives
Others
Reference
42.8
25.8
22.1
1.4
6.1
ND
Gouveia et
al.(2009)
37.35±0.5
23.66±0.9
25.10±0.5
1.79±0.02
3.25±0.2
ND
Garcia (2009)
37.35
23.65
25.09
1.55
3.25
9.11
Fuentes (2009)
43.7±0.7
21.8±0.2
28.0±2.0
ND
ND
ND
Ruzene (2005)
Table 10. Chemical composition of natural bagasse adapted of Rocha et al. (2010),
obtained for different mills, times of year, operational conditions, etc.
Component
Average
Standard Deviation
Confidence Interval
Cellulose
43.03
1.51
0.42
Hemicellulose
25.42
1.90
0.53
Lignin
23.05
1.50
0.42
Extractives
4.78
2.66
0.74
Ashes
2.92
1.28
0.35
8
As shown in the previous tables, the sugarcane bagasse compositions are
variable and reliant on the methods and conditions in which the chemical
analysis was carried out.
2.3
Sugarcane straw
Sugarcane straw is a heterogeneous material since it is composed by tops and
leaves in different proportions, depending upon the recovery method (e.g.
integral harvesting and baling). Average results obtained in proximate analysis
for dry leaves, green leaves, tops are organized in Table 11. According to
Hassuani et al. (2005), the great difference observed between the compositions
of straw fractions was the moisture content. The other components are present
practically in the same proportion: ashes (~4%), fixed carbon (~15%) and
volatile material (~80%). Tables
Table 12 and Table 13 present chemical analysis of sugarcane straw found in
the literature.
Table 11: Average results obtained for dry leaves, green leaves, tops from the
proximate analysis (HASSUANI et al., 2005)
Determination (wt%)
Dry leaves
Green leaves
Tops
Moisture content
13.5
67.7
82.3
Ash*
3.9
3.7
4.3
11.6
15.7
16.4
84.5
80.6
79.3
Fixed
carbon*
Volatile matter*
* Dry
basis
Table 12: Chemical composition of Brazilian straw compiled by Canilha et al. (2012).
Composition (% w/w, dry basis)
Moriya
(2007)1
∗Pitarelo
∗Saad
et al.
(2008)3
∗da
(2007)2
Silva et al.
(2010)4
Luz et al.
(2010)4
Costa et al.
(2012)4
Cellulose
36.1
34.4
36.1
33.6
33.3
33.5
Hemicellulose
28.3
18.4
26.9
28.9
27.4
27.1
Lignin
26.2
40.7
26.2
31.8
26.1
25.8
Ashes
2.1
11.7
2.1
5.7
2.6
2.5
Extractives
5.3
11.5
5.3
Others
10.6
*Extractives-free
basis.
Extracting solvents: 1ethanol; 2dichloromethane, ethanol: toluene (1:2), ethanol, and hot
water; 3water; 4none.
9
Table 13: Sugarcane straw compositions reported in the literature.
Composition (wt%, dry basis)
Oliveira
(2014)
Oliveira
(2013)
Seabra
(2010)*
Moutta
(2012)
Ayala
(2012)
Cellulose
38.1
39.8
32.5
40.84
34.43
Hemicelluloses
29.2
28.6
20.5
30.79
23.61
Lignin
24.2
22.5
17.9
25.80
24.09
Ashes
2.5
2.4
3.9
2.56
9.61
Extractives
5.9
6.2
8.4
7.67
16.8
0.6
Others
*Moisture: 15%
3 Adopted compositions for sugarcane biomass in the VSB
In order to evaluate different biorefinery alternatives, the composition of
sugarcane biomass must be defined. The following sections detail the
assumptions and compositions for each feedstock.
3.1
Sugarcane stalks composition in the VSB
The composition of sugarcane stalks in the VSB was defined based on values
frequently found in the literature (section 2.1). It was observed that fiber content
varied between 8 and 16 wt%, with average values around 13 wt% as shown
in Table 4. In the same table, sucrose content (Pol) was about 14 wt%. These
average values (13 and 14 wt%) were adopted in the VSB for fiber and sucrose
contents, respectively.
Composition of sugarcane stalks adopted in the VSB is shown in Table 14,
expressed in terms of water, fibers, extractives and ashes as well as their
constituents.
The definition of sugarcane composition considered that the bagasse
composition (normalized average from Table 10) was obtained after sugarcane
cleaning and sugars extraction. It was assumed that ashes are composed by
salts, minerals and dirt (residual soil); extractives include a fraction of sugars
and acids remainder from sugarcane after juice extraction. A fraction of the
ashes in the sugarcane bagasse is inherent to the fibers and is represented by
salts in the simulations.
10
Table 14. Composition of sugarcane stalks adopted in the VSB.
3.2
Component
Content (wt%)
Extractives
15.19
- Organic acids
0.56
- Glucose
0.60
- Sucrose
14.00
- Phosphate
0.03
Ashes
1.78
- Minerals
0.20
- Salts
1.31
Water
70.29
Fibers
13.00
- Cellulose
5.99
- Hemicellulose
3.54
-Acetate
0.33
-Xylan
3.21
- Lignin
3.21
- Ashes inherent to the fibers (salts)
0.27
Sugarcane bagasse composition in the VSB
The detailed composition for bagasse is presented in Table 15.
Table 15: Composition of sugarcane bagasse used as reference in the VSB.
Component
Content (wt%, dry basis)
Extractives
Organic acids
4.82
0.45
Glucose
0.18
Sucrose
4.17
Phosphate
0.02
Ashes (salts)
2.94
Hemicellulose
Acetate
25.63
Xylan
2.38
23.24
Lignin
23.24
Cellulose
43.38
Moisture
50.00
11
The fiber breakdown was obtained from bagasse composition in Table 10
(normalized average) whereas extractives were based on sugarcane stalk
composition (Table 14). However, bagasse composition in the simulations may
differ, since it results from the defined sugarcane stalk composition and the
efficiencies for cleaning and extraction considered in the simulation.
3.3
Sugarcane straw composition in the VSB
VSB simulations consider the straw composition provided by Oliveira et al.
(2014), shown in Table 13. Breakdown of hemicellulose, extractives and ashes
were assumed equivalent to that initially considered for sugarcane bagasse
(Table 15). Adopted composition for sugarcane straw is presented in Table 16.
Moisture and soil contents vary according to the straw recovery system (baling
or integral harvesting) and fraction of recovery (CARDOSO, 2013).
Table 16: Composition of sugarcane straw adopted in the VSB.
Component
Content (wt%, dry basis)
Extractives
Organic acids
5.91
0.55
Glucose
0.22
Sucrose
5.11
Phosphate
0.02
Ashes
Salts
Hemicellulose
2.50
2.50
29.23
Acetate
2.72
Xylan
26.51
Lignin
24.22
Cellulose
38.14
4 Final Remarks
The composition of sugarcane biomass is variable and dependent upon the
varieties, source regions, handling conditions, among others. The definition of
a representative feedstock composition is an important initial step for industrial
simulations. Therefore, this technical memorandum is useful for those that are
beginning to build a process model for a sugarcane-based biorefinery. In
addition, this information support future publications including process
simulations of sugarcane biorefinery alternatives carried out using the VSB.
12
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