1. PYROLYSIS
(TORREFACTION AND SLOW PYROLYSIS)

2. TORREFACTION

3. INTRODUCTION
 Continuous rise in world populations and energy needs
 Energy demand and GHG emission
 Increasing demand for clean and sustainable sources of energy
 Coal-fired plants use most coal which produce most of the fossil fuel air
pollution
 1 ton of carbon burned, 3.67 ton of CO2 is generated
 The global use of carbon causes emission of approximately 7 billion
tons/year
 It is projected to reach 14 billion tons/year by 2050
 These global challenges increase in the adoption of alternative sources of
energy

4. BIOMASS CHALLENGES
Biomass materials have several limitations
Low heating value
High moisture content
Hygroscopicity
Excess smoke during combustion
Low energy density
Higher alkali contents
Low combustion efficiency
CONSTITUENTS OF BIOMASS
• Hemicellulose 20 - 40%
• Cellulose 40 - 60 %
• lignin 10 - 25 %

5. CELLULOSE
Linear polymer consists of 45 % of the dry weight of wood
It makes up the fibers in lignocellulosic materials
Its degradation starts from 240 to 350 °C
The waters held in the amorphous regions of the cellulosic wall rupture the structure when converted
into steam as a result of thermal treatment
HEMICELLULOSE
•It is a complex carbohydrate polymer
•It makes up 25–30 % of total dry weight of wood
•Thermal degradation occurs between the temperature of 130–260°C
•Hemicellulose produces less tars and char due to its low degradation temperature range compared to
that of the cellulose
LIGNIN
•Lignin along with cellulose is the most abundant polymer
•Cell wall between components
•It is covalently bonded to hemicelluloses and thereby exhibits mechanical strength on the cell wall
•It is relatively hydrophobic and aromatic in nature
•Decomposes between 280 and 500°C
•Lignin is difficult to dehydrate and thus converts to more char than cellulose or hemicelluloses

6. TORREFACTION
 Torrefaction (French word which means roasting)
 It has been used in a host of industries
 production tea and coffee making
 Now the attention of power industries
 production of a coal substitute from biomass
 Torrefaction is also called a pretreatment process
 Torrefaction is a method to improve biomass properties for energy generation
 It is a thermochemical process in an inert or limited oxygen environment where biomass is
slowly heated to within a specified temperature range and retained there for a stipulated time
which results in near complete degradation of its hemicellulose content while maximizing
mass and energy yield of solid product. It is a endothermic process
 It requires heat thermal decomposition is 0.6–1 MJ/kg
 Torrefaction include the decomposition of hemicellulose and partial depolymerization of
lignin and cellulose
 Torrefied biomass (TB) has higher content of carbon
 Higher calorific value (CV) than the raw biomass

7. Chopping
• Size reduction
• Uniform size
Drying
• Removing the moisture content
• During drying composed of both condensable an non-
condensable gases and volatiles as stated
Torrefaction
• Complete devolatilisation of hemicelluloses
• Improved combustible properties of biomass
PROCESS OF TORREFACTION

8. • At 110 °C
• Increase of temperature initiates the
decomposition of its polymeric
structure and hemicelluloses
Drying
• Decomposition of hemicellulose
• Slight decomposition in lignin and
cellulose
• Majority of biomass weight loss
Torrefaction
PROCESS OF TORREFACTION

9. PROCESS OF TORREFACTION

10. Torrefied biomass retains majority of
its energy content
Torrefaction retains around 70 % of
its mass which contains around 90 %
of its initial
30 % of the mass containing only 10
% of energy content of the biomass
is converted into torrefaction gases
PROCESS OF TORREFACTION

11. MECHANISM OF TORREFACTION

12. HEATING STAGES IN TORREFACTION
Pre-drying
 First step in the process
 Biomass temperature increase from room to the drying temperature (100˚C)
 Temperature rises steadily receiving sensible heat from the reactor or the heating medium
Drying
 It is the most energy-intensive step of torrefaction process
 Moisture in biomass is evaporated during this stage (110to 160˚C)
 This stage makes the biomass in a bone dry condition
Post drying
 The designed torrefaction temperature is generally in excess of 200˚C, because very little
decomposition of the biomass takes place below this temperature
 During this stage, all physically bound moisture along with some light organic compounds
escape from the biomass

13. Torrefaction
 It is key to the whole process
 Bulk depolymerization of the biomass takes place in this stage
 A certain amount of time is needed to allow the desired degree of depolymerization of the
biomass to occur
 The degree of torrefaction depends on the reaction temperature as well as on the time
 This time is also called reactor residence time or torrefaction time
Cooling
 Biomass leaves the torrefier at the torrefaction temperature, which is the highest
temperature in the system
 It is above the ignition temperature
 Torrefied biomass unless cooled down sufficiently the product could catch fire on contact
with air
 Handling of such a hot product is unsafe and dangerous
HEATING STAGES IN TORREFACTION

14. Ideal
temperature
and mass
loss history
of a biomass
particle
undergoing
torrefaction
HEATING STAGES IN TORREFACTION

15. SEQUENTIAL PROCESS OF TORREFACTION

16. DEGREE OF TORREFACTION
 Light Torrefaction
oTemperature of 200-240˚C
oAt 230˚C when only hemicellulose is degraded leaving lignin and cellulose
unaffected
 Medium Torrefaction
oTemperature of 240-260˚C
o At about 250˚C, when cellulose is mildly affected
 Severe Torrefaction
oTemperature of 260-300˚C
oAt 275˚C characterized by depolymerization of lignin, cellulose, as well as
hemicellulose

17. HYDROPHOBICITY OF TORREFIED BIOMASS
 Drying in pre torrefaction stage reduces the moisture of raw biomass
from 10-50%
 After torrefaction, biomass becomes largely hydrophobic or resistant to
water and thus it absorbs very little moisture
 The hydrophobic character of torrefied biomass allows its extended
storage without biological degradation

18. TORREFIED CHAR
 Torrefied biomass is non-polar molecular structure
 It is a attractive solid fuel
 Advantageous for pelletization
 Facilitates storage and transportation
 Co-combustion of biomass with coal
• Hydrophobic behaviour and inhibiting biological decomposition
• Improved grindability
• Higher heating value
CHARACTERISTICS OF TORREFIED MATERIALS

19. EFFECT OF TEMPERATURE AND RESIDENCE TIME
 Temperature
owould result in extensive devolatilization and carbonization of the polymers
oThe loss of lignin in biomass is very high above 300˚C
oThis loss could make it difficult to form pellets from torrefied products
 Fast thermal cracking of cellulose causing tar formation starts at temperature 300-
320˚C
 These reasons fix the upper limit of torrefaction temperature as 300˚C

20. OXYGEN CONCENTRATION
 Another important aspect of torrefaction
 It is not essential to have oxygen-free environment for torrefaction
 Presence of a modest amount of oxygen can be tolerated
 It may even have a beneficial effect on the torrefaction
 Torrefaction is to make the biomass lose its fibrous nature such that it is easily
grindable
 It is still possible to form into pellets without binders
 Such requirements limit the torrefaction temperature in the range of 200-300˚C
• Important characteristic of torrefaction
• It is slow heating rate to allow maximization of solid yield of the process
• Heating rate of torrefaction is less than 50˚C/min
• A higher heating rate would increase liquid yield
HEATING RATE

21. CHANGES TAKING PLACE IN BIOMASS IN THE
THERMOCHEMICAL PROCESS
TEMP.
RANGE
PROCESS THAT OCCURS HEATING
RATE
PROCESS SOLID
PRODUCT
20-110 ˚C The wood is preheated and it approaches
100˚C, moisture starts evaporating
Low/fast Drying Preheated dry
wood
110-200 ˚C Further preheating removes traces of
moisture and slight decomposition starts
Low/fast Post drying
preheating
Bone dry Wood
200-270 ˚C Wood decomposes releasing volatile (e.g.,
acetic acid, methanol, CO, and CO) that
escape
Low Torrefaction Mildly torrefied
wood
270-300 ˚C Exothermic decomposition starts releasing
condensable and no condensable vapors
Low Torrefaction Severely torrefied
wood
300-400 ˚C Wood structure continues to break down.
Tar release starts to predominate
Low
High
Low
temperature
Carbonization
Pyrolysis
Low fixed carbon
Charcoal
Liquid
400-500 ˚C Residual tar from charcoal is
released
Low
High
Carbonization
Pyrolysis
High fixed
carbon
Charcoal
Liquid

22. DIFFERENCE BETWEEN CARBONIZATION,
PYROLYSIS AND TORREFACTION
• Maximize its liquid production
• Minimizing the char yield
Pyrolysis
• Maximize fixed carbon
• Minimize hydrocarbon content of the
solid
Carbonization
• Maximize energy and mass yields
• Reduction in oxygen to carbon (O/C)
and hydrogen to carbon (H/C) ratios
Torrefaction

23. Typical
wood
Torrefied
wood
Charcoal
(Carbonization)
Coal
(Bituminous)
Temperature 200-300 >300
Moisture (%)(wb) 30-60 1-5 1-5 3-20
Volatile (%db) 70-80 55-65 10-12 28-45
FC (%db) 15-25 28-35 85-87 45-60
Mass yield 80% 30%
Energy density (db)
(MJ/kg)
18 20-24 30-32 24-33
Volumetric energy
density (GJ/m3)
5.8 6-10 18.5-19.8 30-40
Apparent density
(kg/m3)
350-680 300-500 600-640 1100-1350
Hydrophobicity Hygroscopic Hygroscopic Hygroscopic Hygroscopic

24. CARBONIZATION
 Relatively high temperature
 Slow and long term process
oTraditional carbonization process uses beehive retort
owood is piled inside a mud covered pit to restrict air
entry
oIt is ignited at the base
oA part of the combustion heat provides the energy
needed for carbonization

25. CHARCOAL FUEL
 It is a smokeless fuel
 The small opening provides oxygen to burn some wood to provide heat
for carbonization
 The oven is closed and well insulated, whatever heat is generated is
retained inside the oven and that helps slow down the thermal
degradation of the wood into charcoal
 The temperature inside the carbonizer could be as high as 800˚C

26. CARBONIZATION
 Solid products of carbonization of biomass include
 Fuel charcoal
 Activated charcoal
 Biocoke
 Biochar
 It have some fine differences primarily for application considerations
 Because of its stable pore structure with high surface area
 All are produced in processes similar to that of torrefaction
 Slow heating in absence or low oxygen
 The major difference lies in the process temperature

27. ACTIVATED CHARCOAL
 It is produced by removing the tarry products from conventional fuel charcoal
 This makes the pores in charcoal more accessible for adsorption
PROCESS
• Heating ground charcoal to about 800˚C in an atmosphere of superheated steam
• The charcoal thus avoids contact with oxygen while distilling away the tar that was
blocking the fine structures of the charcoal
• Steam carries away the tarry residues
• After this the solid product is poured into a sealed container and allowed to cool
• The activation process increases the pore surface area by orders of magnitude

28. BIOCOKE
 It is produced specifically for metal extraction as a substitute for conventional coke
.It is produced from coking coal
 When heated with metallic ores with oxides or sulfides, carbon in biocoke
combines with oxygen, and sulfur allowing easy metal extraction
BIOCHAR
• Carbonization takes place at relatively high temperatures
• Biochar is known for its carbon sequestration potential and soil remediation
properties
• Biochar to the soil that improves the fertility and other properties of the soil
• Carbon in biomass that would have been released to the atmosphere as a
greenhouse gas is now retained as stable solid char in the soil

29. APPLICATION OF TORREFIED CHAR
 Fuel charcoal for energy
 Manufacture of carbon disulfide, sodium cyanide and carbides
 Smelting of iron ores, case hardening of steel and purification in
smelting of nonferrous metals
 Water and gas purification, solvent recover and waste water treatment
 Carbon sequestration and soil remediation

30. TYPES OF TORREFACTION
 Wet torrefaction
 Dry torrefaction
Wet torrefaction : Biomass is subjected to heating in hot compressed
water
Dry torrefaction : It involves heating either by a hot inert gas or by
indirect heating
The dry process is the accepted method for commercial torrefaction

31. CLASSIFICATION OF TORREFACTION
REACTORS
Classification based on mode of heating
 Heating is an important part of the torrefaction process
 A medium carries heat and transfers it to the biomass particles
o Gas-particle convection
o Wall-particle conduction
o Electromagnetic heating of biomass
o Particle-particle heat transfer
o Liquid-particle heat transfer

32. TORREFACTION REACTORS
Based on the mode of heating, torrefaction reactors may be grouped into
◦ Directly heated type
◦ Indirectly heated type
• Biomass is heated directly by a heat-carrying medium
• Heat is exchanged through direct contact between the biomass and the heat carrier
• The heat carrier could be either a hot gas without oxygen or one with limited
amount of oxygen
• It could also be hot nonreactive solids or hot fluid-like pressurized water, steam or
waste oil
DIRECTLY HEATED REACTORS

33. CONVECTIVE REACTOR
(MOVING/FIXED/ENTRAINED BED)
 Fluidized bed
 Hydrothermal reactor
• Rotating drum
• Screw or stationary shaft
• Microwave
INDIRECTLY HEATED REACTORS

34. DESIGN METHODS
Energy required
 Chipping of wood: 180-2360 kJ/kg wood
 Grinding: 270-450 kJ/kg of feedstock
 Drying of raw wood: 3000-9000 kJ/kg water removed
 Torrefaction of dried wood: 130-350 kJ/kg torrefied wood
DESIGN APPROACH
• Drying of raw feed in dryer
• Torrefaction of dried feed in torrefier
• Cooling of torrefied product in cooler
• Torrefaction temperature
• Torrefier residence time

35. CONCLUSION
 Torrefaction improves the physical, chemical and theological characteristics of biomass
materials.
 Torrefied biomass is a group of products resulting from the partially controlled and
isothermal pyrolysis of biomass occurring at the 200–300°C temperature range.
 Torrefaction reactions include devolatilisation and carbonization of hemicelluloses in first
steps and depolymerization and devolatilisation of lignin and cellulose in other step.
 Torrefaction of the biomass helps in developing a uniform feedstock with minimum moisture
content and less affected by atmospheric environment
 Torrefaction of biomass improves energy density, homogeneity, grindability and pelletability
performance
 Calorific value of torrefied biomass is in the range of 18–22 MJ/kg
 The volumetric energy density of torrefied pellets is nearly 16 GJ/Nm3 compared to nearly
10 GJ/m3 of wood pallets

36. BIOCHAR PROCESS

37. INTRODUCTION
• Increased GHG emissions due to use of fossil fuels
• To avoid GHG emissions by reduction in the use of fossil fuels, capturing carbon
dioxide emitted from fossil fuel combustion and through changes in land-use and
agricultural practices.
• One such potential measure is the sequestration of carbon in soils in an inert form
through pyrolysis biochar systems.
• To sequester atmospheric carbon (C) in soil. Biochar is a stable form of C which is
produced from pyrolysis using biological materials.

38. BIOCHAR
 Biochar is a fine grained, highly porous solid material which is rich in
carbon produced at low temperature (400 and 500°C) pyrolysis of
biomass under complete or partial exclusion of oxygen.
Biomass feedstocks Biochar

39. PRODUCTION OF BIOCHAR

40. OTHER BIOCHAR PRODUCTION METHODS AND
ITS PRODUCT YIELD PERCENTAGE
TECHNOLOGY TEMPERATURE
(°C)
RESIDENCE
TIME
CHAR
(%)
LIQUID
(%)
GAS
(%)
Slow pyrolysis ~ 400 °C h-weeks 35 30 35
Intermediate
pyrolysis
~500 °C ~10-20 secs 20 50 30
Fast pyrolysis ~500 °C ~1sec 12 75 13
Gasification ~800 °C ~10-20 secs 10 5 85
Hydrothermal
carbonization
(HTC)
~ 180-250°C
(~1-12 h)
No vapour
residence
time
50-80
5 - 20
(dissolved in
process
water, TOC)
2-5

41. Chimney
Pyrolysis unit
Combustion unit
Data logger unit
SLOW PYROLYZER UNIT FOR BIOCHAR
PRODUCTION
Highlights of the reactor
Capacity – 1 kg
Efficiency – 30 – 32 %
Residence time – 45 – 60 mins

42. 57% of carbon 33% of
carbon
0% + 6% + 4% of carbon
(35 wt %) (40 wt %) (25 wt %)
Biochar retains ~ 20% of the weight and 30% of the energy of the biomass, so ~70% of
the energy is released as usable vapors.
Created by photosynthesis using
solar energy + CO2 + H2O
CHEMICAL CHANGES AS WOOD BECOMES
BIOCHAR

43. CHARACTERIZING CHARS
According to
Structure
Physical and chemical
characterisitics
According to
Function
Phenomenological abilities to
improve plant growth and
microbial processes
ABILITY TO STORE CARBON

44. IMPORTANT CHARACTERISTICS OF BIOCHAR
Properties of biochar Parameters Purpose
Physical properties Bulk density, porosity and particle density To study the effect of biochar when used as soil
amendment
Proximate analysis Moisture content, volatile matter, fixed carbon and ash
content
Percent organic carbon enhanced after biochar
production
Ultimate analysis Carbon, hydrogen, nitrogen and oxygen Elemental composition present in biochar
Organo-chemical properties H / C and O / C Degree of aromoticity
Electro chemical properties pH, EC and CEC For soil pH adjustment, nutrient retention ability,
ions bindability
Nutritive properties N, P, K, Na, Mg, Ca Nutrient content present in biochar
Total carbon determination Total organic carbon present in biochar and C/N ratio Carbon sequestration potential
Thermal Properties Thermo gravimetric analyzer (TGA) and Calorific Value To study the thermal behavior of biochar
Scanning electron microscope (SEM) To study the structure and surface attributes of
biochar
X-ray diffraction (XRD) To study the crystalline nature of biochar
Fourier transform infrared spectroscopy (FTIR) To study the functional groups present in biochar

45. TGAANALYSIS
Coconut shell biochar Casuarina biochar
Thermo Gravimetric Analysis is a type of testing that is performed on samples to
determine changes in weight in relation to change in temperature.

46. SEM ANALYSIS
Coconut shell biochar Casuarina biochar
SEM imaging analysis was conducted using Scanning Electron microscope. Varying magnifications
were used to compare the structure and surface characteristics of the biochar samples.

47. XRD ANALYSIS
COCONUT SHELL BIOCHAR CASUARINA BIOCHAR
X-Ray Diffraction analysis was carried out to identify any crystallographic structure in the biochar
samples using a computer controlled X-ray diffractometer equipped with a stepping motor and
graphite crystal monochromator. XRD is used to characterize the crystalline structure present in the
biochar. It can be interpreted using d-space in the graph.

48. FTIR ANALYSIS
COCONUT SHELL BIOCHAR CASUARINA BIOCHAR
Fourier transform infrared spectroscopy (FTIR) is used for the identification of a sample to determine the
functional groups present in it. The wave number ranges from 470 to 3760 cm-1 Maximum point shows
the bondage between Oxygen and Hydrogen (O-H). Around 1500s there is C-C bond which proves the
biochar compounds are aromatic in structure. Around 3500, indicate the presence of OH group (Water).

49. Important properties of biochar
 High carbon content (60 – 95 % C)
 Resistant to biodegradation
 Significant adsorptive qualities
 Nutrients essentially lock on to the structure
 Increases moisture holding capacity
 Enhances microbial biomass

50. BIOCHAR AS SOILAMENDMENT
Boosts food production and preserves cropland diversity by:
 Increases water retention
 Reduces fertilizer requirements by improving retention of soluble nutrients
 Improves nutrient retention by increasing Cation Exchange capacity (CEC) by
about 50 %
 Reduces nutrient run – off to water ways
 Improves soil biology
 Adjusts soil pH
 Reduces N leaching by 60%, increases crop productivity by 38 to 45%, saving
20% fertilizer and 10 % savings in irrigation and seeds

51. BIOCHAR AND INDIRECT GHG REDUCTION
CO
2
N2
O
CH
4
GHG emission
reduction from
agri. fields
Improves soil structure and
nutrient retention
Stability
Fertility
Improved or
reduced
water usage
Reduced or
no use of
synthetic
fertilizers
Half life -1400 years

52. BIOCHAR’S IMPACT ON CARBON CYCLE

53. BIOCHAR CARBON SEQUESTRATION IS
CARBON NEGATIVE

54. REDUCED N2O EMISSIONS
 Nitrous oxide gas is produced in soil through three biological processes
 Nitrification: In the first stage of nitrification, N2O is produced as a by-product
during the oxidation of ammonium to nitrite.
 Nitrifier-denitrification: In the second stage of nitrification, nitrite is converted
to nitrate; however, under low oxygen (O) conditions, specialized nitrifying
bacteria (denitrifying nitrifiers) use nitrite as an alternative electron acceptor, in
this way producing N2O.
 Denitrification: Here, heterotrophic denitrifying aerobic bacteria cause
respiratory reduction of nitrate or nitrite to N2O and N2 under anoxic conditions.

55. SUMMARY SCHEMATIC FOR REDUCED
EMISSIONS OF N2O FROM SOIL

56. EFFECT OF BIOCHAR ON SOIL PROPERTIES
Properties Rice straw Rice husk Rice husk ash Rice husk biochar
Water content (%) 12.2 11.26 6.74 4.96
BD - - 0.96 0.84
pH - - 8.4 8.7
C (%) 33.4 43.77 5.09 18.72
P (%) 0.1 0.07 0.06 0.12
CEC (cmol kg-1) - - 6.7 17.57
K (%) 0.1 0.12 0.16 0.2
Ca (%) 0.12 0.27 0.33 0.41
Mg (%) 0.18 0.16 0.21 0.42
Na (%) 0.42 0.6 1.26 1.4
Biochar not only mitigate the GHG levels but also improve soil chemical properties (e.g. pH, CEC cation)
physical properties (e.g. Soil water retention, hydraulic conductivity) and crop yields

57. LIFE CYCLE SUSTAINABILITY ASSESSMENT

58. APPLICATIONS OF BIOCHAR
Biochar
Waste
management
Mitigation
of climate
change
Soil
Improvement
Energy
production

59. CONCLUSION
 Biochar production and application in soils has a very promising
potential for the development of sustainable agricultural systems and
also for global climate change mitigation.
 Biochar greatly improves the soil physical properties and
environment factors.
 Applications of biochar to soils not only increase the income of
farmers by increasing crop yields, but also by carbon trade.
 Biochar had to be fully integrated into the carbon trade market which
is not only a scientific, but also a political effort.

60. THANK YOU