UNEP
Characterization of Waste Agricultural Biomass for
Energy Applications
Training onTechnologies for Converting Waste Agricultural Biomass into Energy
Organized by
United Nations Environment Programme (UNEP DTIE IETC)23-25 September, 2013
San Jose, Costa Rica
Surya Prakash ChandakSenior Programme Officer
International environmental Technology CentreDivision of Technology, Industry and Economics
Osaka, Japan
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Why Characterisation of WAB
Characterization of WAB provides essential information for:
• Selection of WAB2E technology• System design• Assessment of operational
performance• Provides data for tendering
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Characterization of waste agricultural biomass
Parameters of characterization• Visual characterization• Moisture content• Chemical Composition• Calorific value• Specific characterization parameters
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Characterization of waste agricultural biomass
Visual characterization
Source Waste Stream Visual Observations
Commercial Facilities Fruit and vegetable waste
High moisture (estimated to be 60-80%), sometimes putrified, mixed with packing hay
Corporate Farms Rice husk Clean, stacked in heaps, approximate volume …m3
Jaggery Plants Bagasse Moist waste (estimated moisture 50%), scattered around, some spread on ground for sun-drying, mixed with barbojo
Private farms -- --
-- -- --
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Characterization of waste agricultural biomass
Moisture contentTwo ways of reporting
Moisture content on wet basis (MCwb)Moisture content on dry basis (MCdb)
Relationship between MCwb and MCdb
.1 wb
wbdb MC
MCMC
0.0
0.5
1.0
1.5
2.0
2.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Moi
stu
re C
onte
nt
on D
ry B
asis
Moisture Content on Wet Basis
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Characterization of waste agricultural biomass
Chemical composition – Ultimate Analysis
Component
Percent by weight (dry basis)
Carbon Hydrogen Oxygen Nitrogen Sulphur Ash
Wheat Straw 48.5 5.5 39.9 0.3 0.1 5.7
Rice Straw 39.2 5.1 35.8 0.6 0.1 19.2
Rice Husk 38.5 5.7 39.8 0.5 <0.01 15.5
Bagasse 46.4 5.4 42.6 0.7 <0.01 4.9
Hard Wood 50.8 6.4 41.5 0.4 <0.01 0.9
Soft Wood 52.9 6.3 39.7 0.1 <0.01 1.0
Corn Cob 46.2 7.67 42.3 1.2 0.3 2.4
Cotton stalk 45.3 5.6 45.3 0.5 <0.01 3.3
Anthracite coal 78.8 2.3 2.5 0.9 0.5 15
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Characterization of waste agricultural biomass
Chemical composition – Proximate Analysis
Component
Percent by weight (dry basis)
Volatile Matter(%dry ash free basis)
Fixed Carbon(%dry ash free
basis)Ash
(% dry basis)
Wheat Straw 83.9 16.1 11.2
Rice Straw 80.2 19.8 19.8
Rice Husk 81.6 18.4 23.5
Bagasse 84.2 15.8 2.9
Wood 77-87 13-21 0.1-2.0
Peanut shell 78.4 21.6 7.2
Corn Cob 85.4 14.6 2.8
Cotton stalk 80.0 20.0 5.3
Anthracite coal 5.9 94.1 15.0
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Characterization of waste agricultural biomass
Energy Content
Three expressions:
Higher Heating Value (HHV) or Gross Calorific Value (GCV)
Lower Heating Value (LHV) or Net Calorific Value (NCV)
Usable Heat Content
HHV – Total energy generated from combustion including the heat of condensation of water vapor – represents maximum theoretical potential energy
LHV -- Total energy generated from combustion less the heat of condensation of water vapor – represents maximum realizable energy
UHC – LHV less the sensible heat of the combustion products – represents actual usable energy
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass
Relationships between heating values– HHV of wet biomass = (1-m)HHVD
– LHV = (1-m)HHVD - (latent heat)(moisture content
in product gas per kg fuel)
= (1-m)HHVD – 2.447[m + 9.0(1-m)H]
– Utilizable heat content =
LHV - [(mass fraction)
(CP)]all products(Texht - Tamb)
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where m is the fractional moisture content in biomass
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass Estimation of Higher Heating Value of WAB
– Usually, heating values of biomass materials are determined
through direct experimental measurement by means of a
device called bomb calorimeter
– Alternative to the practical measurements, approximate
estimations for HHVD could be made through analytical
equations that are derived based on fuel composition
– Based on ultimate analysis
Three models:
– Model – X: HHV=0.352xC + 1.162xH – 0.111xO + 0.063xN + 0.105xS
– Model – Y: HHV=0.349xC + 1.178xH – 0.103xO + 0.015xN + 0.101xS – 0.021A
– Model – Z: HHV=0.341xC + 1.323xH – 0.120xO + 0.120xN + 0.680xS – 0.015A
– HHV – Higher Heating Value in MJ/Kg
– C,H,O,N,S,A are the % mass fractions of Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur and Ash respectively in dry biomass.
– Try matching with the formula !!• Q = 337C + 1442(H - O/8) + 93S
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass Estimation of Higher Heating Value of WAB
Based on ultimate analysis
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Biomass Fuel
Composition (% by weight) HHVD (MJ/kg)
C H O N S Ash ModelX
ModelY
ModelZ
Paddy Straw 39.2 5.1 35.8 0.6 0.1 19.2 15.8 15.6 15.5
Paddy Husk 38.5 5.7 39.8 0.5 0 15.5 15.8 15.7 15.6
Corn Cob 46.2 7.6 42.3 1.2 0.3 2.4 20.5 20.7 20.6
Bagasse 46.4 5.4 42.6 0.7 0 4.9 17.9 18.1 17.7
Cotton Stalk 45.3 5.6 45.3 0.5 0 3.3 17.4 17.7 17.3
Hard Wood 50.8 6.4 41.5 0.4 0 0.9 20.7 21.0 20.7
Soft Wood 52.9 6.3 39.7 0.1 0 1.0 21.5 21.8 21.6
Miscanthus 48.1 5.4 42.2 0.5 0.1 3.7 18.5 18.7 18.4
Barley Straw
45.7 6.1 38.3 0.4 0.1 9.4 18.9 19.0 18.9
Wheat Straw 48.5 5.5 39.9 0.3 0.1 5.7 19.0 19.2 18.9
Lignite 64.0 4.2 19.2 0.9 1.3 10.4 25.4 25.2 24.9
Anthracite Coal
78.8 2.3 2.5 0.9 0.5 15 30.2 29.7 29.3
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass
Estimation of Higher Heating Value of WAB Based on ultimate analysis
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Biomass constituent /Chemical equation
Ultimate Analysis (%) HHVD (MJ/kg)
C H OModel
-XModel
-YModel-
Z
Cellulose / (C6H10O5)x
44.4 6.2 49.4 17.3 17.7 17.4
Hemicelluloses / (C5H8O4)y
45.5 6.1 48.5 17.6 18.0 17.7
Lignin / (C9H10O3(CH3O)0.9 – 1.7)z
58.7 – 61.3
6.5 – 6.9
32.2 – 34.4
24.9 – 25.6
25.1 – 25.8
25.0 – 25.7
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass
Estimation of Higher Heating Value of WAB Based on proximate analysis
Three Models
Model A: HHV = 0.1559xVM + 0.3536xFC – 0.0078xA
Model B: HHV = 0.1708xVM + 0.3543xFC
Model C: HHV = 0.3133x(VM+FC) – 10.8141
HHV – Higher Heating Value in MJ/Kg
VM, FC,A are the % mass fractions of Volatile Matter, Fixed Carbon and
Ash respectively in dry biomass.
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UNEPInternational Environmental Technology Centre
Characterization of waste agricultural biomass Estimation of Higher Heating Value of WAB
Based on proximate analysis
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Biomass Fuel Composition (% by weight) HHVD (MJ/kg)VM
(ash free)FC
(ash free)Ash Model-
AModel-
BModel-
C
Bagasse 84.2 15.8 2.9 18.1 19.4 19.6
Coconut coir 82.8 17.2 0.9 18.8 20.1 20.2
Coconut shell 80.2 19.8 0.7 19.4 20.6 20.3
Coir pith 73.3 26.7 7.1 19.3 20.4 18.3
Corn cob 85.4 14.6 2.8 17.9 19.2 19.6
Corn stalks 80.1 19.9 6.8 18.1 19.3 18.4
Groundnut shell 83.0 17 5.9 17.8 19.0 18.7
Paddy Husk 81.6 18.4 23.5 14.5 15.6 13.2
Paddy Straw 80.2 19.8 19.8 15.5 16.6 14.3
Wheat Straw 83.9 16.1 11.2 16.6 17.8 17.0
Peanut Shell 78.4 21.6 7.2 18.4 19.5 18.3
Cotton Stalk 80.0 20.0 5.3 18.5 19.7 18.9
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UNEPInternational Environmental Technology Centre
Effects of Moisture on Heating Value
Characterization of waste agricultural biomass
15
.-1biomass wet of DHHVmHHV
,,10.92.447--1
fuel) kgper gasproduct in content (moistureheat)(latent --1
HD
D
mmHHVm
HHVmLHV
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Hea
ting
Val
ue (M
J/kg
)
Moisture Content on Wet Basis
LHV
HHV
Wood Pellet (8% moisture)
Air Dried Wood (20% moisture)
Green Wood (50% moisture)
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HAPPY WORKING ON CHARACTERIZATION OF WASTE AGRICULTURAL
BIOMASS
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THANK YOU
For further information:http://www.unep.or.jp