2. Future World Energy Demand
Industrialisation and population growth of emerging countries has increased the world wide
energy demand to an alarming rate
It is expected that energy demand surge up with app. 44 % from current total of 138,000
TWh to 198,000 TWh by the year 2030 (Ref.: Renewable and Sustainable Energy Reviews 16
(2012) 3084– 3094)
World Energy Outlook Report (WEO) 2012, has cited that fossil fuel will remain the main
source of energy with app. 80 % by the year 2035
Ref: http://jcwinnie.biz/wordpress/
3. World Energy Outlook Report 2012 (WEO)
Ref: World energy outlook 2012, ISBN: 978-92-64-18084-0
4. Rapid increasing amount of CO2 in the atmosphere since 1900
CO2 Emission to Atmosphere
World atmospheric concentration of CO2 and average global temperature change
Ref: World energy outlook special report 2013
5. According to renewable global status report in the year 2012, app 19 % of total
energy demand is produced by renewable energies
Share of Global Final Energy Consumption
Ref:: Renewables 2013 Global statues report ISBN 978-3-9815934-0-2
6. Renewable Energies in the World in 2012
Share of renewable energies in primary energy consumption in the world shows that
Europe had around 40 % of share in global renewable energy consumption in 2012.
Eurasia contain Europe and Azerbaijan, Belarus, Kazakestan, Turkey, Turkemenistan, and Uzbekistan
Reference : BP statistical Review of World Energy June 2013. Bp.com/statistical review
7. Share of total energy production in Europe area in 2010 (%)
Renewable energy by 26 % had the second place in total energy production in Europe area
in 2010
Reference : European commission, eurostat. . www.epp.eurostat.ec.europa.eu
Energy Production in Europe Area
8. Renewable Energy Production in Europe
Primary prodcution of renewable energy in Europe area in 2010
Biomass and waste has the first place in Renewable energy Production
Reference : European commission, eurostat. . www.epp.eurostat.ec.europa.eu
9. Biomass
Biological structure derived form living or recently living organism.
Biomass composed carbohydrate polymers (cellulose and hemicellulose) and
aromatic polymer (lignin).
Cellulose (C6H10O5) is the most important structural component of the primary cell
wall of green plants and the most abundant organic polymer on earth.
Hemicellulose present with cellulose in almost all plant cell walls.
Cellulose is crystalline, strong and resistant to decomposition in presence of
heat, but hemicellulose has a little strength in front of heat.
Unique characteristics of biomass as the only renewable and carbon based
resource, makes it more attractive for energy purposes.
Divided into; wet and dry Biomass.
10. Neutral Carbon Cycle of Biomass
Ref.: Center for Environmental Research and Technology, Bourns College of Engineering University of California
11. Future Energy Demand via Biomass
In future energy trends, a major role in the energy supply has been pointed to
biomass
Biomass has been used widely as feedstock for thermal conversion processes
such as combustion, gasification, pyrolysis, and hydrothermal carbonisation to get
various phase of products (solid, liquid and gas) to get energy
Ref: https://ukerc.wordpress.com/
12. Slow Heating of Biomass
Slow heating of biomass can be categorised to five levels of temperature and pressure
that end in various products in each level
Conversion technologies, subdivided into these five groups, which end in different phase
of products in quantity depend on nature of biomass and process condition
Slow Heating of Biomass
Temperature Pressure zone Gases – phase products
< 200 °C 1- 5 bar Drying Mainly H2O in phase of vapour releases from biomass
180 °C – 250 °C
1- 5 bar Devolatilization Removing –OH Structures, acetic acids, organics, CO2
releases from biomass, decomposition of cellulose starts
5 - 20 bar Hydrothermal
Carbonization of
Biomass (HTC)
Main product is char
Pre-treatment for gasification
250 °C – 300 °C 1- 5 bar Torreffaction Deoxygenation, removing O2 from reaction mixture,
complete decomposition of hemicelluloses, decomposition of
cellulose starts
300 °C – 500 °C 1- 5 bar Pyrolysis Char coal is the main product
> 500 °C 1- 5 bar gasification
combustion
Aromatics,H2O,syngas, higher hydrocarbons
13. Typical Yield of Thermo-Chemical Processes
Process Reaction
Conditions
(Temperature [°C],
residence time)
Char
Weight %
Liquid
Weight %
Gas
Weight %
Slow pyrolysis ~400 °C h - week 35% 30% 35%
Mild pyrolysis ~500 °C 10 – 20 sec 20% 50% 30%
Fast pyrolysis ~500 °C 2 sec 12% 75% 13%
Gasification ~800 °C -1400 °C
10 - 20sec
10% 5% 85%
HTC ~180 °C - 250 °C
1-12 hour processing
time
50-80% 5-20%
Dissolved in water
2-5%
15. Torrefaction
Proceeds between 200 C to 300 C, under atmospheric condition
In absence or very limited amount of oxygen and very low heating rate
Hemicellulose deeply decomposes and cellulose and lignin partly decomposes
that starts around 250 C
Moisture of biomass will be removed by evaporation and some organic acids,
such as acetic acid will be driven off
Torrefaction removes oxygen from biomass that causes higher heating value of
the product
Around 70 % of mass is preserved which contain 90 % of initial energy
Aslo remove hydroxyl and –OH groups in biomass and makes it more hydrophobic
Torrefied biomass can be milled easily, and high porosity of biomass increases its
reactivity
More CO and H2 in syngas, but the same quantity of CO2
Torrefaction used as pre treatment for gasification reactor
16. Energy and Mass balance in Torrefaction
willow wood was conducted in Toreffaction process at temperature between 250 C and
300 C with residence times of 10 and 30 minutes
With increasing temperature severe decomposition of cellulose occurs at higher 300 C
Torrefied product has a lower O/C and H/C ratio, so it has properties and character
between wood and coal
17. Torrefaction Process as pre - treatment
Step 1 Step 2 Step 3 Step 4
Unprocessed
wood
Dried wood chips Torrefied wood chips Final wood pellets
Wood chips are
collected and stored,
so they can be used
as biomass
Wood chips are dried
before they undergo
torrefaction process
The wood chips are
heated using microwave
technology within a
rotating drum reactor,
creating a charcoal like
substance
The torrefied wood is
milled and made into
pellets that produce up
to 10 % to 20 % more
energy than untreated
one
18. Pyrolysis
Carry out under 300 °C to 500 °C and almost atmospheric pressure with
residence time between 0.5 second to 24 hour.
Carry out in the absence or nearly without oxygen.
Divided to four groups depend on oven temperature and residence time: Flash,
fast, mild, and slow pyrolysis
Under these conditions, hemicelluloses, cellulose, and lignin decomposes to
char as solid phase, tar as liquid phase, and gases depend on residence time
Heat transfer rate rise up, By increasing oven temperature and in short
residence time ( < 2sec ), dominate product is tar (liquid phase)
Char is the main product of slow and mild pyrolysis with low oven temperature
and high residence time
liquid fractions or condensable gaseous products are the main product of flash
and fast pyrolysis with high oven temperature (app. 500 °C), high heat transfer rate
( app. 1 °C / sec) and very low residence time ( < 2 sec)
Fast and Flash pyrolysis is an effort to maximize liquid products such as
BIO – Oil
19. Typical Yield of Thermo-Chemical processes
Process Oven
temperature
residence time
pressure
Particle size Heat rate Main
products
Heating value
of products
Application
area
Flash
pyrolysis
800 °C – 1000 °C
< 0.5 sec
1-5 bar
< 0.2 mm
Biomass
supply in
form of dust
Very fast
heating rate
> 1 °C/s
Tar products
Bio - Oil
-
Power plants,
diesel, boiler,
resin, fertilizer,
fine chemicals,
transport fuels,
emulsions
Fast
Pyrolysis
500 °C - 600 °C
~ < 2 second
1-5 bar
< 1 mm High heating
rate
>100 °C/min
Tar products
Bio - oil
17
MJ/kg
Power plants,
diesel, boiler,
resin, fertilizer,
fine chemicals,
transport fuels,
emulsions
Mild Pyrolysis 315 °C – 450 °C
10-20 second
1-5 bar
5-50
mm
Controlled
heating rate to
control tar
formation
Char
Bio - coal
19 – 24
MJ/kg
Filtration (water
and air), soil
improvement,
power plant,
pharmaceutical
s
Slow
Pyrolysis
200 °C - 300 °C
30 minute / days
1-5 bar
5-50
mm
0.1 – 0.2
°C/sec
charcoal 25 - 37
MJ/kg
Char coal
(lump)
20. Schematic of Pyrolysis (Char and Bio-oil)
Ref: http://energyfromwasteandwood.weebly.com/
21. Gasification
Controlled partial oxidation of carbonaceous material with less oxygen than
required to complete combustion ( air/fuel < 0.5).
Carry out under 600 °C to 1500 °C and almost atmospheric pressure.
CO2, CO, CH4, H2 and H2Og and trace of higher hydrocarbons such as ethane
(C2H6) and ethene (C2H4) exists in produced gas.
Generally air, steam, air/steam and oxygen are used as gasification agent.
Final produced gas is a function of type of gasifier, operating condition, and
gasification agent.
Different gasification processes, classified by the regime of flow inside gasifier.
Divided to three main groups of fixed bed, fluidized bed, and entrained flow.
low cost and simple design and operation is fixed bed advantageous, but Non
uniform mass and heat transfer in fixed bed gasifier causes high amount of tar and
char in produced gas.
Good mixing and solid contact causes, higher conversion efficiency in fluidized
bed gasifiers, but higher cost of operation is its disadvantageous.
22. Gas Composition and Calorific Value
Calorific value Numerical value Agent Application
Low CV 4 - 6
MJ/Nm3
Air
Steam/ Air
Directly in combustion or
engine fuel
Medium CV 12 -19
MJ/Nm3
Oxygen/ Steam Utilizes as feedstock for
subsequent conversion into
basic chemicals such as
methane or methanol
High CV 40
MJ/Nm3
Hydrogen Mainly in chemical industry
Typical gas composition in gasification process
Produced gas Bio fuel gas (Vol %) Charcoal (Vol %)
N2 50-54 55-65
CO 17-22 38-32
CO2 9-15 1-3
H2 6-22 15-20
CH4 2-3 0-2
LHV (MJ/M3) 5-5.9 4.5-5.6
24. Gasification Process
Drying the feed stock
Happens in temperatures up to 200°C and only water driven off
At 180°C carbon dioxide and acetic acid with –OH structure starts to decompose,
which is called Devolatilization, without chemical or physical decomposing of
biomass
Pyrolysis to produce char
Takes place between 300°C to 500°C, produces a large quantity of tar and gases
containing carbon dioxide
Natural structure of the fuel is broken through exothermal reactions which
release steam, methanol, acetic acid and a considerable amount of heavy
hydrocarbons, depend on residence time
Gasification (combustion and reduction)
Combustion contains both exothermic and endothermic reactions which give a
theoretical oxidation temperature of 1450°C
In reduction area, a number of incombustible gases are converted into
combustible products through a series of reactions, depending on the temperature,
pressure and concentration of the reacting species
30. Quality of the produced gas in gasifiers
Gasification
technology
Feed stock
property
Tar and particle
content
Quality of
produced Syngas
Rank
Down draft Less than 55 mm in size
Up to 25% moisture
Low tar content
Moderate particle
High amount of N2, low
amount of CH4, moderate
amount of CO and H2
●●
Up draft Less than 55 mm in size
Up to 60% moisture
High tar content
Moderate particle
High amount of N2, low
amount of CH4, moderate
amount of CO and H2
●●
Cross draft
10 % to 25% moisture
High tar content
High particle
content
- ●●
Bubbling
fluidized bed
Less than 6 mm in size
< 50% moisture
Depend on the bed
material
C2+ , tar, and particles are
present
High amount of CH4 in
compare with other
technologies, higher CO
and H2
●●●
Circulating
fluidized bed
Less than 6 mm in size
< 50% moisture
High particle in circulating
C2+ , tar, and particles are
present
High amount of N2, low
amount of CO and H2
●●
Entrained flow Less than 0.15 mm in
size
< 15% moisture
Low tar and C2+
In Syngas.
Ash slagging
High amount of CO and
H2, low amount of N2,CO2,
and CH4
●●●
• (poor quality) •••• ( good quality)
31. Mass Balances
Increasing performance variables needs useful measures of mass and energy balances
Reactor Input materials Output materials MCE*
(Without
tar and
ash) %Feed
stock
Air steam Tar Char,
Ash
Dry gas Water
H2Og
Down
Draft
gasifier
20% Reject
pellets, 80 %
wood chips
3.70
(kg/hr)
Air
7.39
(kg/hr)
-
0.04
(Kg/hr)
0.08
(kg/hr)
9.26
(kg/hr)
0.17
(kg/hr)
83 %
Up draft
gasifier
RDF pellets1
5.16
(kg/hr)
Air
12.97 (kg/hr)
0.58
(kg/hr)
0.18
(kg/hr)
0.13
(kg/hr)
16.96
(kg/hr)
0.93
(kg/hr)
90 %
Bubbling
fluidised
bed
Wood pellets
11.5
(kg/hr)
Air
20.4
(kg/hr)
- < 3.46
(kg/hr)
28.44
(kg/hr)
- 89 %
Circulating
fluidized bed
Olive oil
waste
60
(Kg/hr)
P* Air
130
(Kg/hr)
S* Air
32
(kg/hr)
- < 43
(kg/hr)
179
(kg/hr)
- - 80 %
Entrained
flow
Saw dust
0.6
(kg/hr)
Air
0.8
(kg/hr)
-
< 0.27
(kg/hr)
laboratory experiment
1.13
(kg/hr)
-
80 %
32. Carbon Conversion
Carbon conversion is defined as the fraction of carbon in the feedstock
converted to gaseous products
Nature of biomass, air ratio, reaction temperature, pressure and
present of catalyst effects the carbon conversion rate
Higher (ER) leads to lower heating value of gases, but lower (ER),
increases carbon conversion
Steam increases gas quality and heating value of the gases, but
decreases the gas yield because it doesn’t take part in gasification
reactions, so a lower carbon conversion rate is attained
Low operating temperature is equal to incomplete carbon conversion.
High temperature favored the carbon conversion efficiency.
High pressure has negative effect on carbon conversion, however the
experiments show that optimum carbon conversion is reached at low
pressure around 1 bar
33. Carbon Conversion
Gasifier Input feed stock
(carbon flow rate)
Output carbon flow rate
Feed stock
(kg/hr)
Carbon
content
Wt %
Carbon flow
rate
(kg/hr)
Carbon flow
rate
(kg/hr)
Carbon
conversion1
%
Accessible
carbon2
%
Gas yield LHV
(MJ/M3)
Downdraft
gasifier
With air
RT: 900 °C
20% paper
reject pellets
80% wood chips
ER: 0.36
3.70 kg/hr
48.66
Wt %
1.8
(Kg/hr)
1.49
(Kg/hr)
82 % 1.03
(kg/hr)
57 %
8.81
(m3/hr)
5.79
(MJ/M3)
Updraft gasifier
With air/steam
RT: <1200 °C
Wood chips
5.2 (kg/hr)
ER: 0.36
55.72
Wt %
4.29
(kg/hr)
3.24
(kg/hr)
75 % 2.15
(kg/hr)
50 %
20.48
(m3/hr)
5
(MJ/M3)
Bubbling
fluidized bed
With Air
BM: Ni-alumina
BT: 780 -830 °C
Chips of pine
wood
FR: 0.4 -0.8
(kg/hr)
ER: 0.18 -0.45
50
Wt %
0.4
(kg/hr)
0.35
(kg/hr)
87 % 0.25
(kg/hr)
62 %
1.25-2.45
(m3/kg)
3.7-8.4
(MJ/M3)
Bubbling
fluidized bed
with Steam
BM: silica sand
BT: 750 -780 °C
Chips of pine
wood
FR: 1.5 – 4
(kg/hr)
ER: 0 (kg/hr)
50
Wt %
2
(kg/hr)
1.34
(kg/hr)
67 % 0.94
(kg/hr)
47 %
0.86-1.14
(m3/kg)
10.3-13.5
(MJ/M3)
accessible carbons defined as flow rate of carbon in output Syngas, which have LHV value consist of CO, CH4, and CnHm
to carbon flow rate of input biomass feedstock.
34. Carbon Conversion
Gasifier Input feed stock
(carbon flow rate)
Output carbon flow rate
Feed stock
(kg/hr)
Carbon
content
Wt %
Carbon flow
rate
(kg/hr)
Carbon flow
rate
(kg/hr)
Carbon
conversion1
%
Accessible
carbon2
%
Gas yield LHV
(MJ/M3)
Circulating
fluidised bed
With air
BM: silica
sand
Willow
69
(kg/hr)
ER: 0.37
BT:850 °C
48.7
Wt %
33.60
(kg/hr)
27.04
(kg/hr)
81.5 % 12.43
(kg/hr)
37 %
151
(m3/hr)
3.15
(MJ/M3)
Entrained
flow
With air and
steam
Wine
industry
waste4
0.96 kg/hr
ER: NR
RT: 1050 °C
52.61
Wt %
0.5
(kg/hr)
0.3
(kg/hr)
59 % 0.175
(kg/hr)
35 %
1.59
(m3/hr)
9.81
(MJ/M3)
Entrained
flow
With air
Wine
industry
waste4
0.96 kg/hr
ER: NR
RT: 1050 °C
52.61
Wt %
0.5
(kg/hr)
0.47
(kg/hr)
94 % 0.244
(kg/hr)
48 %
2.67
(m3/hr)
5.05
(MJ/M3)
accessible carbons defined as flow rate of carbon in output Syngas, which have LHV value consist of CO, CH4, and CnHm
to carbon flow rate of input biomass feedstock.
35. Hydrothermal Carbonisation (HTC)
Typically HTC of biomass is achieved in water at elevated temperatures of app.
180°C to 250°C and under pressures of about app. 20 to 25 bars for several hours
Very small amount of gas (1-5%) is generated, and most organics remain or are
transformed into solids.
Mainly water is removed from the biomass, hence energy density of the product
will raise and heating value will be increased
Variety of problematic wastes and continuously generated biomass streams are
used such as, human waste (e.g. excrement’s and faecal sludge’s), municipal solid
wastes as well as agricultural residues and algae
Compared to other conversion methods low amount of energy during
processing and low operation temperature is necessary.
In addition to the high conversion efficiency, a low amount of tar and very high
amount of H2 as well as a low CO content in the product could be achieved.
Deploying the process to industrial size has been the key obstacle until now
36. Schematic of Hydrothermal Carbonisation (HTC)
Ref: Suncoal hydrothermal carbonization process www.suncoal.de
http://www.suncoal.de/en/technology/carboren-technology
37. Feedstock Property
Characters of biomass such as moisture content, ash content, volatile
compounds, and particle size has effect on gasification performance
Fuel with moisture more than 30 % makes ignition difficult and reduces the CV
of the produced gas
Moisture content has effect on grind ability of the biomass
Moisture reduces the highest temperature in oxidation zone, leads to
incomplete cracking of hydrocarbons released from pyrolysis zone
In fast or flash pyrolysis due to the high heating rates, fine feed stock with very
low particle size is required
Feed stocks with high moisture content are mostly suitable for biological
conversion technologies such as fermentation, anaerobic digestion, but for
hydrothermal carbonisation (HTC) too
Utilisation of and special kind of pre treatment depends on the used or preferred
conversion technology
