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Biomass Resources, Characterisation and Technologies Prof. Anuradda Ganesh Energy Systems Engineering, IIT Bombay 21 st September 2006

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Page 1: Biomass Resources, Characterisation and Technologies(AG)

Biomass Resources, Characterisation and Technologies

Prof. Anuradda Ganesh

Energy Systems Engineering, IIT Bombay

21st September 2006

Page 2: Biomass Resources, Characterisation and Technologies(AG)

Biomass - a natural solar cell

• What is Biomass?• Why Biomass?• Limitations?• Effective Utilisation of Biomass!

Page 3: Biomass Resources, Characterisation and Technologies(AG)

Any organic matter formed, directly or indirectly,

by virtue of photosynthesis, is called biomass

• Crop residues• Forest residues• Agro-industrial residues• Animal waste• Aquatic plants• Purpose grown trees

• Others like MSW and synthetic organics.

Page 4: Biomass Resources, Characterisation and Technologies(AG)

Why Biomass?

• Fossil fuels are fast depleting

• Gap between supply & demand increasing

• Green house gas emissions steadily increasing and causing concernBiomass is a renewable source and available in abundance

[ Annual emissions of greenhouse gases from fossil fuel combustion and land use change (deforestation) ~ 6.7 and 1.6 Pg C respectively]

[ Earth’s natural biomass replacement represents an energy supply of around 3x1021J a year, of which just under 2% is currently used as a fuel]

Page 5: Biomass Resources, Characterisation and Technologies(AG)

LimitationsCrop residues generated in country side—Low in bulk density

High transportation costs

Seasonal availability

High moisture content, high bio-degradability

Therefore,

Decentralised utilisation preferred

Dedicated system for single biomass is questionable due toseasonal availability, R & D on multi-fuel flexibility

Should be called “feedstock” for fuels rather than “fuel”

Page 6: Biomass Resources, Characterisation and Technologies(AG)

Consequences of Limitations

•Limitation on scale

•Upgradation required for wider use

•Dedicated system for single biomass is questionable due to seasonal availability

•High transportation costs

Page 7: Biomass Resources, Characterisation and Technologies(AG)

Therefore,

• Decentralised utilisation preferred

• Upgradation to better fuel taken up

• R & D on multi-fuel flexibility

Page 8: Biomass Resources, Characterisation and Technologies(AG)

Effective Utilisation of BiomassBiomass

Improved solid fuels(Pellet, Char pellet) Gaseous Fuels

Thermo-chemical Gasification

(Producer Gas)

Bio-chemical Biomethanation

(Bio gas)

Liquid Fuels

Thermo-chemical (Pyrolysis Oil)

Bio-chemical (Ethanol)

Extraction –Trans-esterificationSeed based crop

(Biodiesel)

Page 9: Biomass Resources, Characterisation and Technologies(AG)

Biomass and CoalProperties Coal Biomass

Volatile matter(dry basis)

<20 - ~50% 60 – 90%

Fixed Carbon(dry basis)

~ 40 – ~80% <5 - ~25%

Ash(dry basis)

<10 - ~45% <1 - ~25%

C (d.m.m.f) ~ 80% ~ 50%

H (d.m.m.f) ~ 5- ~10% ~10%

O (d.m.m.f) ~10- ~20% ~ 40%

Calorific value (MJ/kg) 16 - 34 16 - 19

Page 10: Biomass Resources, Characterisation and Technologies(AG)

Flame intensity…If = (dω/dt) h

Where… I - flame or reaction intensity(dω/dt) - weight loss with respect to time

& h - heat content

Therefore, the rapid weight loss of bio-fuels, when compared to any coal compensates for lower calorific values

“Co-firing in spreader-stoker boilers is easily adaptable”

Page 11: Biomass Resources, Characterisation and Technologies(AG)

Surface combustion

CharHeatAir

CO2

Flaming combustion

Biomass

Air Heat

Volatiles

CO2

Heat

Page 12: Biomass Resources, Characterisation and Technologies(AG)

In biomass combustion process,Biomass is having 70% volatiles

Typically 50% Carbon, 10% Hydrogen, 40% Oxygen

Most oxygen is released in ‘combined’ form with

volatiles

About 50% energy is contributed by gas phase

combustion through ‘volatiles’

Rate of release of volatiles is high and different for

different biomass

Therefore, provision of air, mixing are critical

Page 13: Biomass Resources, Characterisation and Technologies(AG)

TGA of Biomass 1 and Biomass 2

Page 14: Biomass Resources, Characterisation and Technologies(AG)
Page 15: Biomass Resources, Characterisation and Technologies(AG)
Page 16: Biomass Resources, Characterisation and Technologies(AG)

Biomass Volatiles Ash Ash deformation temp. range (0 C)

Ash fusion temp. range (0 C)

Arhar stalk 83.47 1.77 1250-1300 1460-1500

Bagasse 75.10 8.03 1300-1350 1420-1450

Bamboo dust 75.32 9.09 1300-1350 1400-1450

Cotton stalk 70.89 6.68 1320-1380 1400-1450

Coconut coir 70.30 2.93 1100-1150 1150-1200

Corn cob 80.20 3.60 800-900 950-1050

Dhaincha stalk 80.32 2.67 < 800 800-900

Groundnut shell 68.12 6.91 1180-1200 1220-1250

Jute stick 75.33 5.67 1300-1350 1400-1450

Kikar (Acacia) 77.01 0.64 1300-1350 1380-1400

Mustard shell 70.09 15.43 1350-1400 1400-1450

Pine needle 72.38 1.50 1250-1300 1350-1400

Rice husk 60.64 19.48 1430-1500 1650

Sal seed leaves 60.03 19.75 1200-1250 1350-1400

Sal seed husk 62.54 9.40 1450-1500 1500-1550

Characteristics of biomass

Page 17: Biomass Resources, Characterisation and Technologies(AG)
Page 18: Biomass Resources, Characterisation and Technologies(AG)
Page 19: Biomass Resources, Characterisation and Technologies(AG)

Conclusions

Every biomass has a characteristic behaviour depending on its

basic composition and morphology of its components.

Ash composition and fusion temperature also influence the

adaptability and suitability.

Physical properties of biomass also play an important role

particularly in sizing of the reactor/hopper and extent of co-firing.

For all thermo-chemical conversion processes pyrolysis plays a key role.

Contd..

Page 20: Biomass Resources, Characterisation and Technologies(AG)

Biomass is not a low grade fuel as the rate of weight loss

compensates for the lower calorific values when compared with coal.

The design and operation however, has to consider the large

flaming combustion/amount of gases and vapours to be handled.

Interchangeability of biomass in a reactor is subject to both the

physical and chemical properties.

Page 21: Biomass Resources, Characterisation and Technologies(AG)

Co-firing…

Co-firing – practice of supplementing a primary or a base fuel with a dissimilar fuel

Recently, in US & Europe, there has been a considerable emphasis

on co-firing biomass fuels with coal in PULVERISED COAL and

CYCLONE BOILERS owned and operated by utilities – to address

issues like CO2 reduction, generation of green power etc.

Page 22: Biomass Resources, Characterisation and Technologies(AG)

Co-firing technology comprises of…

Blending the biomass and coal in fuel handling system and feeding that blend to the boiler

Preparing the biomass fuel separately from coal, and injecting it into the boiler without imparting the conventional coal deliverysystem

Gasifying biomass with subsequent combustion of producer gasin either a boiler or a combined cycle combustion turbine generating plant

Gasifying biomass to partially substitute the furnace oil used ina furnace

Co-firing with natural gas for performance enhancement in biomassand coal-fired boilers

Page 23: Biomass Resources, Characterisation and Technologies(AG)

Lets take a re-look at the properties of biomass…

• Modest heat content : 15-22 MJ/kg• Sulphur : Low• Nitrogen : Low• Volatile / fixed carbon ratio : 3.5 – 5

• Typically fuels co-fired at 10-25% ( mass basis)~ 4 – 10% co-firing on a heat input basis

Also, say we take straw which has very low bulk density of 80 kg/m3

as against coal – 880 kg/m3

A 5% straw/95% coal on mass basis ~ 1m3 straw/1.7 m3 coal blend

i.e., 37% straw on a volumetric basis

Page 24: Biomass Resources, Characterisation and Technologies(AG)

There are three main types

Fixed bed type – typically Grate fired

- Traditional technology developed for coal combustion and combustion of municipal solid waste

- Used for biomass fuels with high moisture content, different particle sizes and high ash content

- Capacities upto 20 MWth

Fluidised bed combustion

- A fairly recent innovation entering into the second generation design

- Sized particles, large scale applications

Dust combustion- suitable for fuels which are dry and small such as saw dust

Technologies for biomass combustion

Page 25: Biomass Resources, Characterisation and Technologies(AG)

Gaseous Fuels from Biomass

Biomethanation/Anaerobic Digestion

Anaerobic decomposition of biomassthrough bacterial action

CO2 + CH4 ( called BIOGAS)(40%) (60%) (C.V- 20MJ/Nm3)+ Nutrient rich organic manure

Biomass: Less lignin and more moisture content

Biomass Clean, combustible gas mixture PRODUCER GAS

Average composition:

CO 19±3H2, 18 ±2 CH4 3 ±1CO2 10 ±2N2 balance

The reactor is called GASIFIER• Calorific value (C.V) of Gas~ 4-5 MJ/Nm3, Acceptable limit : Tar < 100mg/ Nm3

P<50mg/ Nm3

GasificationPartial Combustion

Page 26: Biomass Resources, Characterisation and Technologies(AG)
Page 27: Biomass Resources, Characterisation and Technologies(AG)
Page 28: Biomass Resources, Characterisation and Technologies(AG)
Page 29: Biomass Resources, Characterisation and Technologies(AG)

Liquid Fuels---Concept & Introduction

Ethanol Bio-diesel Pyrolysis oil

Petrol substitute Diesel substitute

Starch/sugar based biomass

Straight Vegetable oil (triglycerides of fatty acids) from oil seeds

Any Bio fuel

Fuel oil substitute (later for diesel)

Page 30: Biomass Resources, Characterisation and Technologies(AG)
Page 31: Biomass Resources, Characterisation and Technologies(AG)

Biomass

Charcoal

Producer Gas

Air

Cooling & Condensing

Air

Air

Heat

Tar Removal

Tar Cracking

Heat ??

Volatiles

Heat

Ash

Condensing

Oil & Chemicals

Vol. Cracking

Useful Carbon

Pyrolysis as we understand today

Page 32: Biomass Resources, Characterisation and Technologies(AG)

Why not (!) Straight Vegetable Oils (SVO) ???

Basic constituent of SVO is ‘Triglycerides’

Small amounts of mono and diglycerides

Substantial amounts of oxygenates

Free fatty acid

OCH2 – O - C- R1

CH – O – C – R2

CH2 – O – C – R3

O

O

A typical triglyceride molecule

High Viscosity – poor injection characteristics, poor atomisation,

inefficient mixing with air, incomplete combustion

Oxidative and thermal polymerisation, deposition on injectors

Therefore, engine must be more or less modified or use derivatives

Page 33: Biomass Resources, Characterisation and Technologies(AG)

Making of Bio-Diesel (from oil of low fatty acid)

O

O

Triglycerides

O

O

CH2 – O - C- R1

CH – O – C – R2

CH2 – O – C – R3

O

CH3OH

NaOH

CH2 – OH

CH - OH

CH2 - OH

R1 - C- O – CH3

R2 – C –O - CH3

R3 – C – O - CH3

ONa

Na

Na

(Na salt of HFA soap)

Bio-diesel(methyl ester of HFA)

(Heating & stirring) Glycerol

+

Page 34: Biomass Resources, Characterisation and Technologies(AG)

I f p e r c e n t a g e o f F r e e F a t ty A c i d s ( F F A ) a r e m o r e , t h e n i t w o u ld f o r m s o a p

R - C - O – H

ON a O H

C H 3 O HR - C - O – N a +

OH 2 O

( S o a p )F F AA c id

c a ta ly s tC H 3 O H

R - C - O – C H 3

O

( E s te r )

Recent advancement…

Two step process using co-solvent (e.g. THF)

High conversion efficiency

Reaction time 30-35 mins.(lower than 6-7 hrs. for one stage process)

Page 35: Biomass Resources, Characterisation and Technologies(AG)

Comparison of SVO and Biodiesel with Diesel

0.200.20(B100)(B100)

0.620.62(B100)(B100)

9911110.050.05Moisture Moisture Content(wt.%)Content(wt.%)(Karl(Karl--Fischer Fischer titrat ion)titrat ion)

162162(B100)(B100)

160160(B100)(B100)

2802802252256666Flash Point(0C)Flash Point(0C)ASTM D93ASTM D93

41.1241.1240.9340.9338.1438.1437.9937.994242Calorif ic Value Calorif ic Value (MJ/kg) (MJ/kg) ASTM D240ASTM D240

878878861861917917969969844844Density (kg/m3)Density (kg/m3)ASTM D4052ASTM D4052--8686

99775858505044Viscos ity at Viscos ity at 404000C (C (cStcSt) ) ASTM D445ASTM D445

Kusum Kusum BiodieselBiodieselB20B20

Karanj Karanj BiodieselBiodieselB20B20

KusumKusumKaranjKaranjDieselDieselOil propertiesOil properties

Page 36: Biomass Resources, Characterisation and Technologies(AG)
Page 37: Biomass Resources, Characterisation and Technologies(AG)

Biorefinery

Page 38: Biomass Resources, Characterisation and Technologies(AG)

Conclusion

• Biomass is a source of carbon and hydrogen (with external alterations)

• It is time for an integrated approach at all levels—small, medium and large scale—for fuels and chemicals from biomass

Page 39: Biomass Resources, Characterisation and Technologies(AG)

Thank You

Page 40: Biomass Resources, Characterisation and Technologies(AG)

Properties of Bio-diesel prepared at IIT Bombay:

S.No. Properties Bio-diesel1. Kinematic viscosity (cm2/s) 6.51

2. Specific gravity @ 300C kg/lit 0.88

3. Density @ 300C 0.875

4. Moisture content (%) 0.4

5. Carbon residue 0.04

6. Flash point (0C) 190

7. Calorific value (kcal/kg) 8880

8. Acid number mgKOH/g 0.836

9. Iodine number 101

10. Copper strip corrosion No.2

11. Carbon (wt %)Hydrogen (wt %)Oxygen (wt %)

771211