1. `i
List of Diagrams.............................................................................................. iii
List of Tables................................................................................................... iii
1 Introduction to Biomass Resources............................................................ 1
1.1 Types of Biomass Resources.................................................................................................1
1.1.1 Residue of agricultural crops.........................................................................................2
1.1.2 Energy plantation.........................................................................................................2
1.1.3 Municipal and Industrial wastes ....................................................................................3
1.2 Status of Biomass Energy......................................................................................................3
1.2.1 Advancements in Biomass Energy Technologies .............................................................3
1.2.2 Biomass Energy in Asian Developing Countries...............................................................4
1.2.3 Biomass Resources in India...........................................................................................4
1.3 Area under Agricultural Crops and Cropping Pattern..............................................................5
1.3.1 Agricultural Crop Residue Production ............................................................................5
1.3.2 Current use of crop residues .........................................................................................5
2 Introduction to Pyrolysis............................................................................ 8
2.1 Types of Pyrolysis.................................................................................................................9
2.1.1 Slow Pyrolysis...............................................................................................................9
2.1.2 Fast Pyrolysis................................................................................................................9
2.1.3 FlashPyrolysis............................................................................................................10
2.1.4 Ultra-rapid Pyrolysis ...................................................................................................10
2.1.5 Pyrolysis in presence of a medium...............................................................................10
2.2 Reactor Designs Capable of Achieving Fast Pyrolysis ............................................................10
2.2.1 Bubbling Fluidized Bed................................................................................................11
2.2.2 Circulating Fluidizing Bed ............................................................................................13
2.2.3 Ablative Pyrolysis........................................................................................................14
2.2.4 Vacuum Pyrolysis........................................................................................................15
2.2.5 Rotating Cone Pyrolysis Reactor..................................................................................16
2.2.6 Free fall reactor..........................................................................................................16

2. `ii
2.2.7 Solar Reactor..............................................................................................................17
3 Pyrolysis Vapor (Bio-oil) Recovery.......................................................... 18
3.1 Pyrolysis Products..............................................................................................................18
3.2 Condensing Methods.........................................................................................................19
3.3 Liquid................................................................................................................................19
3.4 Char and Particulate Separation..........................................................................................20
4 Bio Oil...................................................................................................... 21
4.1 Physical properties of Bio-Oil..............................................................................................22
4.2 Production of Bio-Oil..........................................................................................................22
5 Uses for Bio-oil......................................................................................... 24
5 . 1 Chemical Feedstock Production..........................................................................................24
5.2 Combustion.......................................................................................................................25
5.3 Furnaces and Boilers..........................................................................................................25
5.4 Diesel Engines....................................................................................................................26
5.5 Combustion Turbines.........................................................................................................26
5.6 Upgrading Bio-oil Properties to Higher Value Products.........................................................27
5.7 Bio crude Oil Burner...........................................................................................................29
6 Case Study ............................................................................................... 30
6.1 Solar Assisted Pyrolysis ......................................................................................................30
6.2 Fixed Bed Tubular Reactor..................................................................................................32
6.3 Pyrolysis in Fixed Bed Tubular Reactor ................................................................................34
7 Conclusion................................................................................................ 36
8 References................................................................................................ 37

3. `iii
List of Diagrams
Figure 1 Classification of biomass resource ................................................................................... 2
Figure 2 Process of decomposition of large HC molecules into smaller ones (PyroWiki) ........... 8
Figure 3 Process Schematic for a Bubbling Fluidized Bed Pyrolysis Design [8] ........................ 12
Figure 4 Fluidized Bed Reactor [8] .............................................................................................. 12
Figure 5 Schematic of Circulating Fluidized Bed [8]................................................................... 13
Figure 6Schematic of the NREL Vortex Reactor Fast Pyrolysis Reactor Design [8] .................. 14
Figure 7 BTG Netherlands- Fast pyrolysis unit & cross –section of rotating cone Pyrolyser...... 16
Figure 8 Schematic of Free Fall Reactor [9]................................................................................. 17
Figure 9 Applications of Bio-Oil [3] ............................................................................................ 24
Figure 10 Schematic of the biocrude-oil burner setup.................................................................. 29
Figure 11 Experimental Setup ...................................................................................................... 31
Figure 12The yields of slow pyrolysis products at particle size of 0.425– 0.85 mm [11]............ 32
Figure 13 the yields of fast pyrolysis products at particle size of 0.425– 0.85 mm [11]............. 33
Figure 14 the yields of flash pyrolysis products at pyrolysis temperature of 550 ºC and particle
size of 0.6– 1.25 mm [11] ............................................................................................................ 34
Figure 15 Fixed Bed Pyrolysis System [12] ................................................................................. 34
List of Tables
Table 1 Area under different crops and their respective residue production in India [7] ............... 6
Table 2 Quantity of agricultural residues used as fodder,fuel and for other purposes in India (Mt)
[7].................................................................................................................................................... 6
Table 3 Amount of non-fodder crop residues potentially available for energy use [7] .................. 7
Table 4 Characteristics of different pyrolysis processes [2].......................................................... 9
Table 5 Pyrolysis reactions at different temperatures. [13] .......................................................... 18
Table 6 Composition of Bio-Oil [2].............................................................................................. 21
Table 7 Physical properties of Bio-oil [2]..................................................................................... 22
Table 8 List of Pyrolysis reactors all over world and its capacity [4] .......................................... 30

4. `1
1 Introduction to Biomass Resources
Biomass is defined as bio-residue available by water based vegetation, forest or organic
waste, by product of crop production, agro or food industries waste.Biomass resources refers
to waste organic material from harvesting or processing agricultural products including
animal waste and rendered animal fat, forestry products including wood waste and sewage
[2].
As a sustainable and renewable energy resource, biomass is constantly being formed by
the interaction of CO2, air, water, soil and sunlight with plants and animals. Biomass includes
only living and recently dead biological species that can be used as fuel or in chemical
production. It does not include organic materials that over many millions of years have been
transformed by geological processes. Unlike fossil fuel, biomass does not take millions of
years to develop. Plants use sunlight through photosynthesis to metabolize atmospheric
carbon dioxide and grow. The biomass grows through photosynthesis by absorbing CO2 from
the atmosphere. When it burns, it releases carbon dioxide that the plants had absorbed from
the atmosphere only recently. Thus, any burning of biomass does not add to the Earth’s
carbon dioxide inventory. For this reason biomass is considered a ―carbon neutral‖ fuel.
Presently, the biomass sources contribute 14% of global energy and 38% of energy in
developing countries. Globally, the energy content of biomass residues in agriculture based
industries annually is estimated at 56 exajoules (1018
), nearly a quarter of global primary
energy use of 230 exajoules. Technological advancement in biomass energy is derived from
the production practices and energy conversion technologies. Improvements in soil
preparation, cultivation methods, species matching, bio-genetics and disease control have led
to enhanced yields. Developments of improved harvesting and post harvesting technologies
have also contributed to reduction in production cost of biomass energy. Technological
advancements in biomass energy conversion comes from enhanced efficiency of energy
conversion technologies, improved fuel processing technologies and enhanced efficiency of
end-use technologies. Versatility of modern biomass technologies to use variety of biomass
feedstock has enhanced the supply potential [1].
Some of the technologies that have been focussed are biomass gasifier integrated with
I.C. engine to generate electricity, Cogeneration in sugar industries by bagasse firing (CHP),
production of bio-ethanol, bio-diesel through various methods, biogas from waste and
hydrogen production from biomass. A concept of bio-refinery facility that integrates different
biomass conversion processes and equipment to produce fuels, power, and chemicals from
biomass is proposed [2].
1.1 Types of Biomass Resources
 Agricultural resources- food grains, bagasse (crushed sugarcane), corn stalks, straw,
seed hulls, nutshells, manure from cattle, poultry, hogs.
 Forest: trees, wood waste, wood or bark, sawdust, timber slash and mill scrap.

5. `2
 Municipal: sewage sludge, refuse-derived fuel (RDF), food waste, waste paper, and
yard clippings. Energy: poplars, willows, switchgrass, alfalfa, prairie bluestem, corn,
soybean, canola, and other plant oils.
 Biological: animal waste, oil-rich algae, aquatic species, biological waste [1].
Figure 1 Classification of biomass resource
1.1.1 Residue of agricultural crops
India has huge amount of agriculture land area, so massive residues are produced.
These residue contents the potential of biomass feedstock for the use of energy generation.
All the organic materials produced as the by-product from processing harvesting of
agricultural crop are termed as agricultural residue. These can further be categorized as
primary and secondary residue. Residues which are obtained in the field at the time of yield
are primary residues which are ricestraw, sugarcane tops etc. whereas those are assembled
during processing are secondary residue. Ricehusk and bagasse are example of secondary
residue. Primary residues are so used as animal feed, fertilizers, etc. Therefore its availability
or energy application is low. While secondary residues are obtained in large quantity at
yielding site and can be confined as energy source. Indian bagasse potential is found to be
12,143.9 kT/year. Whereas total bio-residue available is 511,041.39kT/year [1].
1.1.2 Energy plantation
Crops that have been used for biomass power include the corn, sugarcane, grains,
pulses, rubber, etc. Residues form crop obtained as biomass for energy application are dry

6. `3
and wet biomass. These crops have typical properties such as calorific value , moisture and
ash content and carbon proportion which are significant for wet and dry biomass conversion
into useful energy. Biomasses used currently as energy plantation are kadam, babul, bamboo,
Julie flora, Meliadubia. The other potential sources of energy are agro based industries, road
side shrubs, vegetable market, road sweeping, etc. are the area where significant amount of
biomass waste is generated and disposed in distributed manner due to poor and unorganized
management.
1.1.3 Municipal and Industrial wastes
Wastewaters and discharges from industries generate problems of soil and water
pollution. Solid wastes from food industries such as vegetable flay, stale food, fruits and
vegetable rejects, usually disposed of in landfill dumps, make a potential feedstock for biogas
generation by anaerobic digestion. Liquid wastes generated by fruit and vegetables contain
dissolved organic matters like sugar, starch, etc. that can be an aerobically digested to
produce biogas or fermented to produce ethanol. Potential of CH4 production is not able in
India due to them ore production of animal manure which is composition of organic matter
and moisture. Sewage is also source of biomass energy similar to the animal waste. Millions
of tones of municipal solid waste is collected which is composed of paper and plastic by
80%. These MSW can be converted into energy either using anaerobic digestion or direct
combustion. Waste from sugar industries like bagasse can be used in cogeneration plants [1]
[2]
1.2 Status of Biomass Energy
Biomass materials are used since millennia for meeting myriad human needs including
energy. Main sources of biomass energy are trees, crops and animal waste. Until the middle
of 19th century, biomass dominated the global energy supply with a seventy percent share
(Grubler and Nakicenovic, 1988). Among the biomass energy sources, wood fuels are the
most prominent. With rapid increase in fossil fuel use, the share of biomass in total energy
declined steadily through substitution by coal in the nineteenth century and later by refined
oil and gas during the twentieth century. Despite its declining share in energy, global
consumption of wood energy has continued to grow. During 1974 to 1994, global wood
consumption for energy grew annually by over 2 percent rate. Presently, the biomass sources
contribute 14% of global energy and 38% of energy in developing countries (Woods and
Hall, 1994). Globally, the energy content of biomass residues in agriculture based industries
annually is estimated at 56 exajoules, nearly a quarter of global primary energy use of 230
exajoules (WEC, 1994).[6]
1.2.1 Advancements in Biomass Energy Technologies
Technological advancement in biomass energy is derived from two spheres - biomass energy
production practices and energy conversion technologies. A rich experience of managing
commercial energy plantations in varied climatic conditions has emerged during the past two
decades (Hall et al, 1993). Improvements in soil preparation, planting, cultivation methods,

7. `4
species matching, bio-genetics and pest, disease and fire control have led to enhanced yields.
Development of improved harvesting and post harvesting technologies has also contributed to
reduction in production cost of biomass energy. Technological advancements in biomass
energy conversion comes from three sources - enhanced efficiency of biomass energy
conversion technologies, improved fuel processing technologies and enhanced efficiency of
end-use technologies. Versatility of modern biomass technologies to use variety of biomass
feedstock has enhanced the supply potential. Small economic size and co-firing with other
fuels has also opened up additional application. [5]
For electricity generation, two most competitive technologies are direct combustion and
gasification. Typical plant sizes at present range from 0.1 to 50 MW. Co-generation
applications are very efficient and economical. Fluidized bed combustion (FBC) is efficient
and flexible in accepting varied types of fuels. Gasifiers first convert solid biomass into
gaseous fuels which is then used through a steam cycle or directly through gas
turbine/engine.
Gas turbines are commercially available in sizes ranging from 20 to 50 MW. Technology
development indicates that a 40 MW combined cycle gasification plant with efficiency of 42
percent is feasible at a capital cost of 1.7 million US dollars with electricity generation cots of
4 cents/ KWh (Frisch, 1993). [6]
1.2.2 Biomass Energy in Asian Developing Countries
Biomass remains the primary energy source in the developing countries in Asia. Share of
biomass in energy varies - from a very high over three quarters in percent in Nepal Laos,
Bhutan, Cambodia, Sri Lanka and Myanmar; nearly half in Vietnam, Pakistan and
Philippines; nearly a third in India and Indonesia, to a low 10 percent in China and 7 percent
in Malaysia (FAO, 1997). In the wake of rapid industrialization and marketization during past
two decades, the higher penetration of commercial fossil fuels in most Asian developing
nations has caused decline in the share of biomass energy. The absolute consumption of
biomass energy has however risen unabatedly during past two decades, growing at an annual
rate of over 2 percent (FAO, 1997). Various factors like rising population and shortages or
unaffordability of commercial fuels in rural and traditional sectors have sustained the
growing biomass use. The increasing pressure on existing forests has already lead to
considerable deforestation. Despite policy interventions by many Asian governments, the
deforestation in tropics far exceeded afforestation (by a ratio of 8.5:1) during the 1980’s
(Houghton, 1996).
The deforestation and land degradation has made tropical Asian forests the net emitters of
atmospheric CO2 (Dixon et al, 1994). The sustainable growth of biomass energy in Asia
therefore would require augmenting existing biomass resources with modern plantations and
energy crops and by introducing efficient biomass energy conversion technologies. Lately,
many Asian countries have initiated such programs. [6]
1.2.3 Biomass Resources in India
Biomass contributes over a third of primary energy in India. Biomass fuels are predominantly
used in rural households for cooking and water heating, as well as by traditional industries.

8. `5
Biomass delivers most energy for the domestic use (rural - 90% and urban - 40%) in India.
Renewable energy is contributed 10.5% of total electricity generation out of which 12.83%
power is being generated using biomass. Wood fuels contribute 56% of total biomass energy.
India has surplus agricultural and forest area which comprises about 500 million metric tons
of biomass availability per year. In India total biomass power generation capacity is 17,500
MW. At present power being generated is 2665 MW which include 1666 MW by
cogeneration. Biomass resources in India are in different form that can be classified simply in
the way they are available in nature. Sources of biomass energy can be classified as residue
of agricultural crops, energy plantation and municipal and industrial waste. [6]
1.3 Area under Agricultural Crops and Cropping Pattern
In India, out of the total geographic area of 328 million hectare (Mha), the net cropped area
accounts for about 43% and it appears that the net cropped area has stabilized around 140
Mha since 1970. However, the gross cropped area has increased from 152.8 Mha in 1960 to
about 168.6 Mha in 1996–97 and is likely to reach 178.2 Mha by 2010. In India there are two
main cropping seasons, namely Kharif (based on south-west monsoon) and Rabi (north-east
monsoon). Gross cropped area includes land areas subjected to multiple cropping (normally
double cropping) in irrigated land. Net irrigated area has increased substantially from 24 Mha
during 1960-61 to 55 Mha by 1996-67.Rice and wheat are the dominant crops, together
accounting for 41% of cropped area, while pulses, oil seeds and other commercial crops
account for 13.8%, 15.9% and 10.2% respectively. [7]
1.3.1 Agricultural Crop Residue Production
The residue production varies from crop to crop. The data on the residue to product ratio
(RPR) are given in Table 1. The straw to grain ratio of the cereals varies from 2.5 for maize
to 1.6 for wheat. Straw, a low-density residue, is the dominant residue. Rice husk, a by-
product of rice milling, accounts for 20% of paddy. Unlike the cereals, crops such as red
gram, cotton, rapeseed, mustard, mulberry and plantation crops produce woody (ligneous)
residues. Residue production for mulberry, coconut and sugarcane were estimated based on
field studies.
The total crop residue production in India during 2010 was 699 Mt of air dry weight (Table
1). The dominant residues are those of rice, wheat, sugarcane and cotton accounting for 66%
of the total residue production. Sugarcane and cotton residue production is 110 and 50 Mt,
respectively [7].
1.3.2 Current use of crop residues
The use of crop residues varies from region to region and depends on their calorific values,
lignin content, density, palatability and nutritive value. Residues of most of the cereals and
pulses have fodder value. However, woody nature of residues of a few crops restricts their
use to fuel purpose only. The dominant end uses of crop residues in India are as fodder for
cattle, fuel for cooking and thatch material for housing.

9. `6
In India, dung use as fuel is wholly restricted to the domestic sector, while crop residues are
used as fuel in both domestic and industrial sectors. Ligneous and hardy crop residues
namely, rice (husk), maize (cobs) and stalks of redgram, cotton, mulberry, coconut fronds and
shells are mainly used for fuel purpose. About 44 Mt of sugarcane bagasse is used as fuel in
sugar mills, and in small-scale crude rural sugar producing units. The total residue use as a
fuel in India, for 2010 is 165.4 Mt. Reported estimates of different types of biomass used as
fuel is given in Table2. [7]
Table 1 Area under different crops and their respective residue production in India [7]
Crop Residue Production(2010) Residue to
final
economic
produce ratio
Type of
Residue
Gross
Cropped
Area
(Mha)
Total
Economic
Production
(Mt)
Total Residue
Production
(Mt)air dry
Rice 46.1 118.8 213.9 1.8 straw+ husk
Wheat 28.5 98.5 157.6 1.6 straw
Jowar 5.3 6.1 12.2 2.0 stalk
Bajra 8.6 6.8 13.6 2.0 stalk+ cobs
Maize 6.6 13.0 32.5 2.5 straw
Groundnut 9.3 12.2 28.1 2.3 shell+ waste
Sugarcane 5.5 463.5 185.4 0.4 bagasse+
leaves
Cotton 10.1 15.9 55.7 3.5 seeds+ waste
Table 2 Quantity of agricultural residues used as fodder,fuel and for other purposes in India (Mt) [7]
Crop Fodder Fuel Other
Rice 173.0 23.8 17.2
Wheat 136.2 0.0 21.4
Jowar 12.3 0.0 0.0
Bajra 12.3 0.0 1.4
Maize 26.4 6.2 0.0
Groundnut 0.0 3.7 24.4
Sugarcane 21.9 76.0 87.5
Cotton 0.0 55.7 0.0

10. `7
Table 3 Amount of non-fodder crop residues potentially available for energy use [7]
Crop 1996-97 2010
Mt PJ Mt PJ
Rice 26.7 347 41 532
Wheat 8.8 115 21.4 278
Bajra 0 0 1.4 18
Maize 5.3 69 6.2 80
Groundnut 20.7 284 28.1 384
Rape seeds and Mustard 13.8 189 24.1 330
Sugarcane 99.7 1562 163.5 2581

11. `8
2 Introduction to Pyrolysis
Pyrolysis is a thermochemical decomposition of biomass into a range of useful products,
either in the total absence of oxidizing agents or with a limited supply that does not permit
gasification to an appreciable extent. During pyrolysis, large complex hydrocarbon molecules
of biomass break down into relatively smaller and simpler molecules of gas, liquid, and char.
Pyrolysis of biomass is typically carried out in a relatively low temperature range of 300 to
650 °C.
Pyrolysis involves heating biomass or other feed in the absence of air or oxygen at a
specified rate to a maximum temperature, known as the pyrolysis temperature, and holding it
there for a specified time. The nature of the product depends on pyrolysis temperature and
heating rate. The initial product of pyrolysis is made of condensable gases and solid char. The
condensable gas may break down further into non condensable gases (CO, CO2, H2, and
CH4), liquid, and char. The generic reaction representing pyrolysis process is given as [2]-
→ ∑ ∑
Figure 2 Process of decomposition of large HC molecules into smaller ones (PyroWiki)

12. `9
2.1 Types of Pyrolysis
Pyrolysis may be broadly classified as slow and fast on the basis of heating rate. If the
time, theating, required to heat the fuel to the pyrolysis temperature is much longer than the
characteristic pyrolysis reaction time, tr, it is considered as slow pyrolysis and vice versa.
t (heating) >> t(reaction): Slow pyrolysis
t (heating) << t (reaction): Fast pyrolysis
Slow and fast pyrolysis is carried out generally in the absence of medium. The Hydrous-
(H2O) and hydro-(H2) pyrolysis are the other types conducted in specific medium, used
mainly for production of chemicals.
Table 4 Characteristics of different pyrolysis processes [2]
Pyrolysis process Residence
Time
Heating Rate Final Temp.
(o
C)
Products
Carbonization Days Very low 400 Charcoal
Conventional 5-30 min. low 600 Char, bio-oil, gas
Fast < 2 sec Very high 500 Bio-oil
Flash < 1 sec High <650 Bio-oil,
chemicals, gas
Ultra-rapid < 0.5 sec Very high 1000 Chemicals, gas
Vacuum 2-30 sec Medium 400 Bio-oil
Hydro-pyrolysis < 10 sec High < 500 Bio-oil
Methano-Pyrolysis < 10 sec High >700 Chemicals
2.1.1 Slow Pyrolysis
Carbonization is a slow pyrolysis process, in which the production of charcoal or char
is the primary goal. The biomass is heated slowly in the absence of oxygen to a relatively low
temperature (~400 °C) over an extended period of time, to maximize the char formation.
Carbonization allows adequate time for the condensable vapour to be converted into char and
non-condensable gases.
Conventional pyrolysis involves all three types of pyrolysis product (gas, liquid, and
char). As such, it heats the biomass at a moderate rate to a moderate temperature (~600 °C).
The product residence time is on the order of minutes.
2.1.2 Fast Pyrolysis
The primary goal of fast pyrolysis is to maximize the production of liquid or bio-oil.
The biomass is heated so rapidly that it reaches the peak (pyrolysis) temperature before it
decomposes. The heating rate can be as high as 1000 to 10,000 °C/s, but the peak temperature
should be below 650 °C if bio-oil is the product of interest. However, the peak temperature
can be up to 1000 °C if the production of gas is desirable. The important features of the fast
pyrolysis process that help increase the liquid yield are:
(1) Very high heating rate

13. `10
(2) Reaction temperature within the range of 425 to 600°C
(3) Short residence time (<3 s) of vapour in the reactor. (4) Rapid quenching of the product
gas.
2.1.3 Flash Pyrolysis
In flash pyrolysis biomass is heated rapidly in the absence of oxygen to a relatively
modest temperature range of 450 to 600 °C. The product, containing condensable and non-
condensable gas, leaves the pyrolyzer within a short residence time of 30-1500 msec. Upon
cooling, the condensable vapour is then condensed into a liquid fuel known as bio-oil. Such
an operation increases the liquid yield while reducing the char production. A typical yield of
bio-oil in flash pyrolysis is 70 to 75% of the total pyrolysis product.
2.1.4 Ultra-rapid Pyrolysis
This involves extremely fast mixing of biomass with a heatcarrier solid, resulting in a
very high heat-transfer and hence heating rate. A rapid quenching of the primary product
follows the pyrolysis, occurring in its reactor. A gas–solid separator separates the hot heat-
carrier solids from the non-condensable gases and primary product vapours, and returns them
to the mixer. They are then heated in a separate combustor. Then a non-oxidizing gas
transports the hot solids to the mixer. A precisely controlled short uniform residence time is
an important feature of ultra-rapid pyrolysis. To maximize the product yield of gas, the
pyrolysis temperature is around 1000°C for gas and around 650°C for liquid.
2.1.5 Pyrolysis in presence of a medium
In hydropyrolysis, thermal decomposition of biomass takes place in an atmosphere of
high-pressure hydrogen. Hydropyrolysis can increase the volatile yield and the proportion of
lower-molar mass hydrocarbons. Hydrous pyrolysis is the thermal cracking of the biomass in
high-temperature water. In a two-stage process, the first stage takes place in water at 200 to
300 °C under pressure, in the second stage the produced hydrocarbon is cracked into lighter
hydrocarbon at a temperature of around 500 °C. High oxygen content is an important
shortcoming of bio-oil. Hydropyrolysis can produce bio-oil with reduced oxygen [2].
2.2 Reactor Designs Capable of Achieving Fast Pyrolysis
During the last twenty-five years of fast pyrolysis development a number of different
reactor designs have been explored that meet the heat transfer requirements noted above
while also attempting to address the cost issues of size reduction and moisture content of the
feed. These are described in more detail in a comprehensive survey published by Bridgewater
and Paecocke and fall under the following general categories:
• Fluidized bed
• Transported bed
• Circulating fluid bed
• Ablative (vortex and rotating blade)

14. `11
• Rotating cone
• Vacuum
The rotating blade type of ablative reactor along with the rotating cone and vacuum pyrolysis
reactors do not require an inert carrier gas for operation. When issues of product vapor
collection and quality are considered, the lack of a carrier gas when conducting fast pyrolysis
can be a real advantage. This is because the carrier gas tends to dilute the concentration of
bio-oil fragments and enhances the formation of aerosols as the process stream is thermally
quenched. This in turn makes recovery of the liquid oil more difficult. Another disadvantage
is those high velocities from the carrier gas entrain fine char particles from the reactor, which
then are collected with the oil as it condenses. A general discussion of the advantages and
disadvantages of each reactor design follows [8]
2.2.1 Bubbling Fluidized Bed
Bubbling fluidized bed reactors have been used in petroleum and chemical processing
for over fifty years and therefore have a long operating history. As reactor designs, they are
characterized as providing high heat transfer rates in conjunction with uniform bed
temperatures, both being necessary attributes for fast pyrolysis. By selecting the appropriate
size for the bed fluidizing media, the gas flow rate can be established such that gas/vapour
residence time in the freeboard section above the bed can be set to a desired value, generally
between 0.5-2.0 seconds. Experience has shown that an operating temperature of 500°-550°C
in the bed will usually result in the highest liquid yields at about 0.5 sec residence time;
however larger systems can operate at a somewhat lower temperature and a longer residence
time. The temperatures may also vary depending on the type of biomass being processed. The
largest units in operation are a 200 kg/hr unit by Union Fenosa in Spain and a 400 kg/hr unit
by DynaMotive in Canada
In principle, the bubbling bed is ―self-cleaning,‖ which means that by product char is carried
out of the reactor with the product gases and vapours. However, in practice this requires
using carefully sized feedstock with a relatively narrow particle size distribution. If biomass
particles are too large the remaining char particles (after pyrolysis) may have too much mass
to be effectively entrained out of the reactor with the carrier gas and product vapours. The
density of this char will be less than that of the fluidizing media and, consequently, this char
will ―float‖ on top of the bed. In this location it will not experience enough turbulence with
the bed media to undergo attrition into smaller particles that will eventually leave the reactor.
Another issue with having the char on top of the bed is that it will have a catalytic influence
on the vapours as they pass through it on their way out of the bed. This can affect the yields
and the chemical nature of the resulting liquid product. On the other hand, if fines are present
in the feed, then the feed must be introduced lower in the bed otherwise the fines will be
quickly entrained out of the bed before complete pyrolysis can occur. In general, char
accumulation in the bed should be prevented. The design should include a means for
skimming and discharging char from the top of the bed. If this is not done the feed will need
to be carefully screened to obtain a narrow particle size distribution. This in turn will add

15. `12
considerably to the feedstock preparation costs. A schematic of a typical fluidized bed is
shown below in figure 3. [8]
Figure 3 Process Schematic for a Bubbling Fluidized Bed Pyrolysis Design [8]
Figure 4 Fluidized Bed Reactor [8]
Some design considerations in bubbling fluidized bed systems:
• Heat can be applied to the fluid bed in a number of different ways that offer flexibility
for a given process.
• Vapor residence time is controlled by the carrier gas flow rate
• Biomass feed particles need to be less than 2-3 mm in size
• Char can catalyse vapor cracking reactions so it needs to be removed from the

16. `13
bed quickly
• Char can accumulate on top of the bed if the biomass feed is not sized
properly, provisions for removing this char may be necessary
2.2.2 Circulating Fluidizing Bed
This reactor design also is characterized as having high heat transfer rates and short
vapor residence times which makes it another good candidate for fast pyrolysis of biomass.
It is somewhat more complicated by virtue of having to move large quantities of sand (or
other fluidizing media) around and into different vessels. This type of solids transport has
also been practiced for many years in refinery catalytic cracking units, so it has been
demonstrated in commercial applications. Circulating bed technology has been extensively
applied to biomass pyrolysis by Ensyn Technologies under the name of Rapid Thermal
Processing (RTP). Other organizations involved in developing this type of pyrolysis
technology are CRES (Greece) and ENEL (Italy). Various system designs have been
developed with the most important difference being in the method of supplying heat. Earlier
units were based on a single indirectly heated reactor, cyclone, and standpipe configuration,
where char was collected as a by-product. Later designs incorporated a dual reactor system
such as that operated by ENEL in Italy. In this design the first reactor operates in pyrolysis
mode while the second one is used to burn char in the presence of the sand and then transfers
the hot sand to the pyrolysis vessel. Such an option has advantages but also is more
challenging because of solids transport and temperature control (overheating of sand in the
combustor) in the system. Sand flow rate is also 10-20 times greater than the biomass feed
rate and there is a high energy cost in moving this sand around the loop.
Feed particles sized for a circulating bed system must be even smaller than those used
in bubbling beds. In this type reactor the particle will only have 0.5-1.0 seconds (s) residence
time in the high heat transfer pyrolysis zone before it is entrained over to the char combustion
section in contrast to the bubbling bed where the average particle residence time is 2-3 s. [8]
Figure 5 Schematic of Circulating Fluidized Bed [8]

17. `14
2.2.3 Ablative Pyrolysis
The vortex reactor was developed at SERI (now NREL) from 1980 until 1996 to
exploit the phenomena of ablation. In this approach the biomass particle is melted /
vaporized from one plane or side of its aspect ratio. This design approach had the potential to
use particle sizes up to 20 mm in contrast to the 2 mm particle size required for fluidized bed
designs. Biomass particles were accelerated to very high velocities by an inert carrier gas
(steam or nitrogen) and then introduced tangentially to the vortex (tubular) reactor. Under
these conditions the particle was forced to slide across the inside surface of the reactor at
high velocities. Centrifugal force at the high velocities applied a normal force to the particle
against the reactor wall. The reactor wall temperature was maintained at 625°C, which
effectively melted the particle in a fashion similar to butter melting on a hot skillet. Vapors
generated at the surface were quickly swept out of the reactor by the carrier gases to result in
vapor residence times of 50-100 milliseconds. So this design was also able to meet the
requirements for fast pyrolysis and demonstrated yields of 65% liquids. A schematic of this
design is shown in Figure 6.
In practice it was necessary to incorporate a solids recycle loop close to the exit of the
reactor to re-direct larger incompletely pyrolyzed particles back to the entrance to insure
complete pyrolysis of the biomass. Particles could escape the reactor only when they were
small enough to become re-entrained with the vapor and gases leaving the reactor. While the
solids recycle loop was able to effectively address the issue of insuring all particles would be
completely pyrolyzed it also resulted in a small portion of the product vapors being recycled
into the high temperature zone of the reactor. This portion of vapors effectively had a longer
residence time at the pyrolysis reactor temperature and most likely resulted in cracking of the
product to gases thus resulting in slightly lower yields compared to other fluidized bed
design[8]
Figure 6Schematic of the NREL Vortex Reactor Fast Pyrolysis Reactor Design [8]

18. `15
Other design issues with the vortex reactor were:
• High entering velocities of particles into the reactor caused erosion at the transition
from linear to angular momentum.
• Excessive wear was also realized in the recycle loop. Both wear problems were
exacerbated when inert tramp material (stones, etc.) were introduced with the
feed.
• There were uncertainties about the scalability of the design related to maintaining
high particle velocities throughout the length of the reactor. The high velocities are
necessary for centrifugal force to maintain particle pressure against the reactor wall.
The high sliding velocity and constant pressure of the particle against the 600°C
reactor wall are necessary to achieve the high heat transfer requirements for fast
pyrolysis.
Because of these issues the vortex reactor design concept was abandoned in 1997. [8]
2.2.4 Vacuum Pyrolysis
While this is a slow pyrolysis process (lower heat transfer rate) it generates a
chemically similar liquid product because the shorter vapor residence time reduces secondary
reactions. However, the slow heating rates also result in lower bio-oil yields of 30-45 wt%
compared to the 70 wt% reported with the fluid bed technologies. The process itself is very
complicated mechanically, involving a moving metal belt that carries the biomass into the
high temperature vacuum chamber. There are also mechanical agitators that periodically stir
the biomass on the belt; all of this mechanical transport is being done at 500°C. These design
features are expected to have high investment and maintenance costs. Operating at a vacuum
requires special solids feeding and discharging devices to maintain a good seal at all times.
Heating efficiency is low and, in this particular design, unnecessarily complex in the use of a
burner and an induction heater with molten salts as a heat carrier.[8]
Figure 7 Vacuum Pyrolyser (PyroVac)

19. `16
2.2.5 Rotating Cone Pyrolysis Reactor
The Rotating Cone Pyrolysis Reactor has been under development at the University of
Twente in The Netherlands since the early 1990s. Recent activities have involved scale up of
the system to 200 kg/hr. This technology is analogous to the transported bed design
(circulated fluidized bed) in that it co-mingles hot sand with the biomass feed to affect the
thermal pyrolysis reactions. The primary distinction is that centrifugal force resulting from a
rotary cone is used for this transport instead of a carrier gas. The biomass feed and sand are
introduced at the base of the cone while spinning causes centrifugal force to move the solids
upward to the lip of the cone. As the solids spill over the lip of the cone, pyrolysis vapors are
directed to a condenser. The char and sand are sent to a combustor where the sand gets re-
heated before introducing at the base of the cone with the fresh biomass feed. This design has
demonstrated yields of 70% on a consistent basis. [8]
Figure 7 BTG Netherlands- Fast pyrolysis unit & cross –section of rotating cone Pyrolyser
2.2.6 Free fall reactor
The system is comprised of free fall reactor with auxiliary heater, temperature
controller and spiral feeder, vapour condenser, gas purification and collection unit. Biomass
micron fuel is an energy material containing various plant fibres processed in micron sized
biomass powder fuel through an efficient crushing process. The homogeneity and bulk
densities are improved significantly. The controlled process conditions of fast pyrolysis
experiments are pyrolys is temperature, BMF particle size, and feed velocity. Experiments
were carried out by varying one operational parameter with the other two unchanged to
examine their individual influence on the product distribution.
The order of the effects of the factors on bio-oil yield of BMF pyrolysis is pyrolysis
temperature > particle size > feed velocity. The bio-oil yield first increased and then declined.
There was an optimum pyrolysis temperature for bio-oil production from BMF pyrolysis.
Small particle size of the biomass powder was conducive to the bio-oil production, and larger
particle size led to poor heat transfer thus increasing the yield of non-condensable gases and
char. The increase in feed velocity within a certain range was favourable for the increase of
the bio-oil yield. The optimal conditions for bio-oil production from BMF fast pyrolysis were
determined as temperature at 500o
C, biomass particle size smaller than 91 µm and feed
velocity at 12.5 g/min. Under the optimal conditions, the yield of bio-oil reached the
maximum of 41.05 wt. % [9]

20. `17
Figure 8 Schematic of Free Fall Reactor [9]
2.2.7 Solar Reactor
The use of solar reactors in pyrolysis provides a suitable means of storing solar energy
in the form of chemical energy. This type of reactor is usually made with a quartz tube which
has opaque external walls exposed to concentrated solar radiation. A parabolic solar
concentrator is attached with the reactor to concentrate the solar radiation. The concentrated
solar radiation is capable of generating high temperatures (>700 °C) in the reactor for
pyrolysis processes. However, solar reactors have some advantages over slow reactors. In
slow pyrolysis a part of the feedstock is used to generate the process heat. Therefore it
reduces the amount of feedstock available and, at the same time, causes pollution. Hence
utilization of solar energy in the pyrolysis process maximizes the amount of feedstock
available and overcomes the prolusion problem. Moreover, solar reactors are capable of faster
start up and shut down periods compared to slow reactors.

21. `18
3 Pyrolysis Vapor (Bio-oil) Recovery
3.1 Pyrolysis Products
The three primary products obtained from pyrolysis of biomass are char, permanent
gases, and vapours that at ambient temperature condense to a dark brown viscous liquid.
Maximum liquid production occurs at temperatures between 350 and 500 °C. This is because
different reactions occur at different temperatures in pyrolysis processes. Consequently, at
higher temperatures, molecules present in the liquid and residual solid are broken down to
produce smaller molecules which enrich the gaseous fraction. Yield of products resulting
from biomass pyrolysis can be maximized as follows: (1) charcoal—a low temperature, low
heating rate process, (2) liquid products—a low temperature, high heating rate, short gas
residence time process, and (3) fuel gas—a high temperature, low heating rate, long gas
residence time process. Table 6 summaries the products created at different pyrolysis
conditions. Products from pyrolysis processes also strongly depend on the water content in
the biomass which produces large quantities of condensate water in the liquid phase. This
contributes to the extraction of water-soluble compounds from the gaseous and tar phases,
and thus a greater decrease in gaseous and solid products. [4]
Table 5 Pyrolysis reactions at different temperatures.[13]
Condition Processes Products
Below 350 °C Free radical formation, water Formation of carbonyl and
elimination and carboxyl, evolution of CO and
depolymerization CO2, and mainly a charred
residue
Between 350 °C Breaking of glycosidic linkages Mixture of levoglucosan, anhydrides
and 450 °C of polysaccharide by and oligosaccharides in the form of a
substitution tar fraction
Above 450 °C Dehydration, rearrangement and Formation of carbonyl compounds
fission of sugar units such as acetaldehyde, glyoxal and
acrolein
Above 500 °C A mixture of all above processes A mixture of all above products
Condensation Unsaturated products condense A highly reactive char residue
and cleave to the char containing trapped free radicals
Once the pyrolysis vapors are generated in the reaction vessel it is a critical processing
requirement that they be thermally quenched from the high reaction temperatures. This is
important to preserve the compounds that comprise the bio-oil; otherwise many of these
compounds will further crack to permanent gases or polymerize to char. [13]

22. `19
3.2 Condensing Methods
Upon cooling, the pyrolysis vapors have a tendency to form aerosols, which are
submicron droplets. This phenomenon is enhanced if large amounts of carrier gas are present
with the oil vapors when condensation occurs. Because of their size these droplets are very
difficult to separate from the permanent gas stream. A number of techniques have been used
over the years with the most effective probably being liquid spray scrubbing. Simple column
scrubbers and venturi scrubbers have both been used successfully. The key to these devices is
generating spray droplets that are very small so they can effectively collide with the bio-oil
aerosol droplets. Venturi scrubbers can also be effective but a high-pressure drop (>10 kPa)
penalty must be paid, and this pressure loss may not be available from the process.
Electrostatic precipitators have also been used successfully for capturing pyrolysis aerosols
but they can be tricky to operate and are more expensive than simple scrubbers.
Devices such as mist eliminators and coalescing filters are very effective in
removing liquid mists and aerosols from gas streams but they are not practical for the
pyrolysis processes described above because particulates are present along with the
aerosol. The particulates will rapidly plug the small openings in these devices.
Staged condensation with a series of shell and tube heat exchangers has also been used
but this was only about 90% efficient in capturing bio-oil aerosols. While not quite as
efficient in capturing aerosols as the spray scrubber, the staged system had the advantage of
collecting the liquids as fractions or ―thermal cuts‖. This may have some advantages if one is
seeking to extract certain compounds from the whole oil such as in a bio-refinery application.
[8]
3.3 Liquid
The liquid yield, known as tar, bio-oil, or bio crude, is a black tarry fluid containing up
to 20% water. It consists mainly of homologous phenolic com-pounds. Bio-oil is a mixture
of complex hydrocarbons with large amounts of oxygen and water. While the parent
biomass has an LHV in the range of 19.5 to 21 MJ/kg dry basis, its liquid yield has a lower
LHV, in the range of 13 to 18 MJ/kg wet basis (Diebold et al., 1997).
Bio-oil is produced by rapidly and simultaneously depolymerizing and fragmenting the
cellulose, hemicellulose, and lignin components of biomass. In a typical operation, the
biomass is subjected to a rapid increase in temperature followed by an immediate quenching
to ―freeze‖ the intermediate pyrolysis products. Rapid quenching is important, as it prevents
further degradation, cleavage, or reaction with other molecules. [8]
Bio-oil is a microemulsion, in which the continuous phase is an aqueous solution of the
products of cellulose and hemicellulose decomposition, and small molecules from lignin
decomposition. The discontinuous phase is largely composed of pyrolytic lignin
macromolecules (Piskorz et al., 1988). Bio-oil typically contains molecular fragments of
cellulose, hemicellulose, and lignin polymers that escaped the pyrolysis environment
(Diebold and Bridgwater, 1997). The molecular weight of the condensed bio-oil may exceed
500 Daltons (Diebold and Bridgwater, 1997). Compounds found in bio-oil fall into the
following five broad categories (Piskorz et al., 1988)-Hydroxyaldehydes, Hydroketones,
Sugars and dehydrosugars, Carboxylic acids, Phenolic. [8]

23. `20
3.4 Char and Particulate Separation
Char is one of the co-products produced during the conversion of biomass to bio-oil.
Because of the relatively low reaction temperatures (500º-600ºC) employed during
pyrolysis, all of the mineral matter in the starting biomass ends up being sequestered in the
char. This phenomenon has some benefits in offering techniques to effectively manage the
minerals in biomass but can also impact the quality of the resulting bio-oil. Work done at
NREL in the mid-1990s showed that char played a major role in the long-term stability of
bio-oils. This role will be discussed in more detail in the section on Properties of Bio-oil, but
for now the discussion will focus on char and particulate removal techniques applied during
the pyrolysis processing steps.
Ideally it would be desirable to separate the char while it is in the vapor stream before the
vapor is cooled and condensed to a liquid. All of the processes described above attempt to do
this by using cyclone separators at the exit of the high temperature reaction vessel. Proper
design of cyclones specifies the required entering velocities, vortex finder length & diameter,
cone angle, etc. for a given particle loading in the gas stream. When designed properly for
optimum separation efficiency, the pressure drop across the cyclone needs to be at least 1.5
kPa. The limitation on cyclones, however, has to do with the particle size (or actually particle
mass). They are not very effective on particles below 2-3 microns and all pyrolysis processes
generate char particles under this size. The exception to this would be the vacuum pyrolysis
system developed by PyroVac. Since this process does not involve carrier gas and sand
attrition of the char, there is little to no entrainment of char with the vapor stream in this
design. Instead the char is mechanically transported out of the reaction vessel. So in practice,
almost all pyrolysis processes produce bio-oils that contain a certain level of char fines. [8]

24. `21
4 Bio Oil
It is any liquid fuel derived from a recently living organism, such as plants and their residues
or animal extracts .In view of its properties, a detailed discussion of bio-oil is presented next.
Bio oil is a liquid fraction of the pyrolysis product of biomass. For example a fast pyrolyser
typically produces 75% bio oil, 12% char, and 13% gas. Bio-oil is a highly oxygenated, free
flowing, dark brown (nearly black) organic liquid that contains a large amount of
water(~25%) that is partly the original moisture in the biomass and partly the reaction
product. The composition of bio-oil depends on the biomass it is made from as well as on the
process used.
Following table shows the composition of a typical bio-oil.
Table 6 Composition of Bio-Oil [2]
Major group Compounds Mass(%)
Water 20-30
Lignin fragments Insoluble pyrolytic lignin 15-30
Aldehydes Formaldehyde,
acetaldehyde,
hydroxyacetaldehyde,
glyoxal, methylglyoxal
10-20
Carboxylic acids Formic, acetic, propionic,
butyric, pentanoic, hexanoic,
glycolic
10-15
Carbohydrates Cellobiosan, alpha-D-
laevoglucose,
oligosaccharides, 1.6
anhydroglucofuranose
5-10
Furfurals 1-4
Alcohols Methanol, ethanol 2-5
Ketones Acetol, cyclopentanone 1-5
It shows that water, lignin fragments, carboxylic acids, and carbohydrates constitutes it's
major components. When it comes from the liquid yield of pyrolysis, bio-oil is called
pyrolysis oil. Bio-oil may be seen as a two phase microemulsion. In the continuous phase are
the decomposition products of hollocellulose; in the discontinuous phase are the pyrolytic
lignin macromolecules. Hollocellulose is the fibrous residue that remains after the
extractives, lignin, and ash-forming elements have been removed from the biomass.
Bio-oil is a class 3 substance falling under the flammable liquid designation in the UN
regulations for transport of dangerous goods (Peacocke and Bridgwater et al., P.1485) [2]

25. `22
4.1 Physical properties of Bio-Oil
It is a free flowing liquid due to its low viscosity and high water content. Also, it has an
arid, smoky smell that can irritate eyes with long term exposure .With specific gravity of
~1.2, bio-oil is heavier than water or any other oil derived from petroleum. A comparison of
its physical and chemical properties with those of conventional fossil fuels is listed below in
table no. Bio-oil is not soluble in water, although it contains substantial amount of water.
However, it is miscible in polar solvents, such as methanol and acetone, but immiscible with
petroleum derived oils. Bio-oil can accept water up to maximum limit of 50% (total
moisture).Any more water results in phase separation. Table 6 shows that bio-oil has a
heating value nearly half that of conventional liquid fuels but has comparable flash and pour
points.
Table 7 Physical properties of Bio-oil [2]
Property Bio-oil Heating Oil Gasoline Diesel
Heating
value(MJ/kg)
18-20 45.5 44 42
Density
@15ºC(kg/m³)
1200 865 737 820-950
Flash point(ºC) 48-55 38 40 42
Pour point(ºC) -15 -6 -60 -29
Viscosity
@40ºC(cP)
40-100(25%
water)
1.8-3.4 0.37-0.44 2.4
pH 2.0-3.0 - - -
Solids(% wt) 0.2-1.0 - 0 0
Elemental Analysis(% weight)
Carbon 42-47 86.4 84.9 87.4
Hydrogen 6.0-8.0 12.7 14.76 12.1
Nitrogen <0.1 0.006 0.08 392ppm
Sulphur <0.02 0.2-0.7 1.39
Oxygen 46-51 0.04
Ash <0.02 <0.01
4.2 Production of Bio-Oil
Several options for the production of bio-oil are available. They are either thermochemical or
biochemical.
 Gasification of biomass and the synthesis of the product gases into liquid
(thermochemical)
 Production of biocrude using fast pyrolysis of biomass (thermochemical)
 Production of bio-diesel (fatty acid methyl ester, or FAME) from vegetable oil or fats
through transesterification (biochemical)
 Production of ethanol from grains and cellulosic materials (biochemical)

26. `23
The important steps in the production of bio-oil from biomass are as follows:
1. Receipt at the plant and storage
2. Drying and sizing
3. Reaction (pyrolysis, gasification, fermentation, hydrolysis, etc.)
4. Separation of products into solids, vapor (liquid), and gases
5. Collection of the vapor and its condensation into liquid
6. Upgrading of the liquid to transport fuel or extraction of chemicals from it.

27. `24
5 Uses for Bio-oil
Bio-oil has the potential for multiple applications. These can range from a variety of
combined heat and power options to the extraction of selected chemicals. Use as a substitute
for hydrocarbon fuels in conventional prime movers to produce electricity or generate steam
has been demonstrated but has not been commercially adopted. This is primarily due to
lower cost for petroleum-based fuels compared to bio-oils. However, in some applications
with more sophisticated prime movers such as internal combustion engines and
aeroderivitive turbines, quality issues with the oil must still be addressed. Upgrading of bio -
oils to higher value transportation fuels requires de-oxygenation and reforming of most of
the compounds present in the bio-oil. Because of the large amount of oxygen present there
will be a loss in mass (or volume) yield but this will be balanced against higher heating
values. Overviews of these applications are provided below.
5.1 Chemical Feedstock Production
Bio-oil is a hydrocarbon similar to petrocrude except that the former has more oxygen. Thus,
most of the chemicals produced from petroleum can be produced from bio-oil. These include:
 Resins
 Food flavorings
 Agro-chemicals
 Fertilizers
 Levoglucosan
 Adhesives
 Preservatives
 Acetic acid
Figure 9 Applications of Bio-Oil [3]

28. `25
5.2 Combustion
Sandia National Laboratory conducted fundamental single droplet combustion studies
of bio-oils produced at NREL, including hot gas filtered oil. Despite the major differences
between petroleum fuels compared to bio-oil, the burnout time for bio-oil was comparable to
#2 fuel oil. The bio-oil however demonstrated a sequential burnout ending with formation
and subsequent burnout of cenosphere particles. This property may present problems with
soot formation during combustion. Also unique to the bio-oil was micro-explosion of the
droplet as it transitioned through the combustion sequence. The phenomenon of the micro-
explosion was also observed to be different depending on the cracking severity in which the
oil was produced. It is not known if this droplet micro-explosion will cause combustion
problems in large burner applications or impact the resulting combustion products. Full-scale
combustion tests on bio-oil conducted in flame tunnels at MIT and CANMET did not show
fundamental differences in combustion behaviour compared to #2fuel oil. However, the NOx,
CO, and particulate emissions from bio-oil were higher. Other studies in Europe have
reported similar findings with a clear correlation of the emissions to the quality of the bio-oil,
in particular the residual char fines content. [8]
5.3 Furnaces and Boilers
Furnaces and boilers are commonly used for heat and power generation. Technologically
they produce less efficient combustion compared to turbines and engines. On the other hand,
furnaces and boilers can operate with a great variety of fuels ranging from natural gas and
petroleum distillates to sawdust and coal/water slurries. Therefore bio-oil seems to be more
suitable for boiler applications as long as it meets acceptable emission levels, economic
viability and consistent quality characteristics. Several studies have been conducted using
pyrolysis bio-oil in boiler applications to replace heavy fuel oil. The important findings of
these studies could be summarized as follows:
 Pyrolysis bio-oils have significantly different combustion characteristics compared to
fossil fuels;
 Bio-oils with high viscosity and high solids and water content exhibit worse
combustion performances in boilers;
 Different pyrolysis bio-oils differ in combustion behaviour and exhaust gas
emissions; The flame from bio-oil combustion is longer compared to that
of standard fossil oil;
 Harmful gas emissions from pyrolysis bio-oil in boiler applications are lower than
from burning heavy fuel oils except for particulate levels;
 Some modifications of the burners and boilers are required for proper utilization of
pyrolysis bio-oil in heat and power generation. [8]

29. `26
5.4 Diesel Engines
Medium and slow speed diesel engines are known for their ability to run on low quality
fuels, even such fuels as coal slurries. In the early 1990s researchers began investigating the
use of bio- oils in these engines. Solantausta conducted pioneering work in this area using a
high-speed single cylinder engine with a compression ratio of 15:1. It was very difficult to get
the bio-oil to auto-ignite without substantial amounts of nitrated ignition additives. In
addition, carbon deposits formed at the injectors causing plugging problems. Additional
studies conducted on larger scale medium speed engines, equipped with pilot fuel
capabilities, showed more promise. While auto-ignition was not a problem it was difficult to
maintain proper adjustment on the injectors, and excessive wear and corrosion were seen in
the injector loop. Much of this was attributed to the acidity and particulate matter in the oil.
Additional testing was done at the University of Kansas and MIT using the very clean hot gas
filtered oil produced at NREL. When Suppes at the University of Kansas blended methanol
and a cetane enhancer with these clean oils they exhibited performance characteristics similar
to conventional diesel fuel. If high compression ratios are employed, the solvent blended oils
would even perform well in high-speed engines. At MIT, Shihadeh showed that the clean oils
had much better combustion characteristics (shorter ignition delay, faster burn out and less
coking) than non-filtered oil. He also demonstrated that these clean oils would auto-ignite if
the combustion air were preheated to 55°C. More recently, testing of emulsions of diesel fuel
and bio-oil at 50:50 blends were successfully demonstrated as an alternative way to get
around the auto ignition problem.
With only minor modifications to the engines, these early results indicate that bio-oils
have the potential to replace conventional diesel fuel in low to moderate speed stationary diesel
engines. The difficulties encountered with wear and corrosion appears to be solvable with proper
selection of materials for key components and improved particulate removal from the oil.
Bio-oil contains less hydrogen per carbon (H/C) atom than do conventional transport
fuels like diesel and gasoline, but it can be hydrogenated (hydrogen added) to make up for
this deficiency and thereby produce transport fuels with a high H/C ratio. The hydrogen
required for the hydrogenation reaction normally comes from an external source, but it can
also be supplied by reforming a part of the bio-oil into syngas. This method is practiced by
Dynamotive, a Canadian company. [8]
5.5 Combustion Turbines
Combustion turbines are a well-established technology that offers the potential of
producing power (and heat) at relatively high efficiencies. They are primarily fuelled on
petroleum distillates or natural gas but if properly designed, in conjunction with appropriate
fuel specifications, they should be able to operate on any fuel including bio-oil. Of critical
importance in these devices is particulates and alkali metal content in the fuel. This is
especially important if sulphur is also present due to alkali sulphate formation during the
combustion process. Alkali sulphates will stick to and aggressively corrode the turbine
blades. Fortunately, biomass is very low in sulphur but it does contain alkali (K and Na) and
alkali earth (Ca and Mg) metals that are sequestered in the char during pyrolysis. A small
portion of this char is typically entrained with pyrolysis vapors and captured with the bio-oil

30. `27
product. Consequently one of the key issues to using bio-oils in combustion turbines is the
effective removal of char from the oil. The acidic nature, low heating value, and higher
viscosity properties of bio-oil can be addressed by appropriate design and material selection
in the turbine.
Since 1995, Orenda Aerospace Corp. (Canada) has been investigating the use of bio-
oils in a combustion turbine application. They have selected a turbine designed by
Mashproekt in the Ukraine because of its robust design for low quality fuels. It also
employs advanced coating in the entire hot section of the turbine to protect against alkali
contaminants. Andrews et al tested this 2.5 MW turbine on bio-oil fuel (after starting on
diesel) and ran it through its full operating range from idle to full power without any
difficulties. Measured emissions on bio-oil were lower for NOx, SOx, and HC but higher
for particulates. The higher particulates may have been due to higher levels of char in the
bio-oil but this property was not measured. Orenda has recently started to market this
turbine for bio-oil applications, which implies they feel confident about the performance of
the Mashproekt turbine operating on bio-oil fuel.
Strenziok et al., at the University of Rostock in Germany, tested a smaller commercial
75 kW turbine on bio- oils. In this demonstration the combustion chamber was modified to
enable dual fuel operation with diesel and bio-oil. Under dual fuel operation they were able
to achieve 73% of the full output power that would have been obtained from diesel alone.
The ratio of fuel blend was 40% bio-oil and 60 % diesel. When compared to straight diesel
operation the CO and HC emissions were higher while the NOx was lower.
As with diesel engine applications, these early results show that it is indeed possible to
operate turbines on bio-oil fuels. These results were achieved with only minor modifications
of existing equipment and little effort was expended in tailoring the oil properties
specifically for turbine operation. [8]
5.6 Upgrading Bio-oil Properties to Higher Value Products
As noted in the previous section, bio-oil quality can be improved to move it into a
different grade and therefore command a higher price for the producer. The simplest and least
expensive methods involve adding solvents or limited amounts of water to bring the bio-oil
into the desired viscosity range. If solvents such as alcohols are used, added benefits accrue
by adjusting the heating value and gaining improved long term storage properties. Solids in
the form of ash and attired fluidizing media can be removed by filtration, either hot (vapor
phase) or after the oil has been condensed. This processing step will add complexity and
additional operating costs to the final product. We should point out that while filtration has
been demonstrated, both approaches have inherent difficulties that will require additional
development before they can be considered commercially viable. These physical upgrading
techniques can improve the quality of the neat, as produced, bio -oil but will still require the
designer of end use equipment to make significant modifications to address the chemical
properties of bio-oil, including acidity and low heating values because of high oxygen
content.
If bio-oils could be upgraded chemically to produce a product that looked more like
petroleum hydrocarbons then the end use device would require little to no modification.

31. `28
This would be the fastest way to gain acceptance of biomass-based fuels into the existing
infrastructure. This approach essentially involves de-oxygenation and subsequent reforming
of the remaining hydrocarbons. Two approaches have been explored for chemical
upgrading of these oils: catalytic cracking and catalytic hydrotreating.
Diebold and Scahill and others investigated in situ cracking of promptly formed
biomass pyrolysis vapors over zeolite cracking catalysts. A number of zeolite cage sizes
along with different doping metals were explored but the standard Mobile ZSM-5 catalyst
developed for the methanol to gasoline process gave the best results. Oxygen is rejected in
the form of H 2O, CO2, and CO and the remaining hydrocarbons are re-arranged to form
mostly aromatic type hydrocarbons because of the shape selectivity of zeolite catalysts for
these types of hydrocarbons. Although conversion efficiencies of 42 wt% are theoretically
possible, in practice only about half of this value was obtained in C2 + hydrocarbons. High
coking rates on the catalyst (up to 15 wt %) were a major contributor to the low yield.
An alternate approach using catalytic hydrotreating showed more promise. Elliott et al
and others have been developing this approach to chemical upgrading. Early work using low-
activity sulphidecatalysts showed that it was necessary to carry out the hydrotreating in two
steps. The first step (at lower temperature) initially stabilized the more reactive lower
molecular weight compounds, which was followed by higher temperature more aggressive
hydrotreating of the more stable phenolic compounds. This effort resulted in higher yields
than those seen for catalytic cracking but also produced a similar highly aromatic product
composition. Although aromatics have a relatively high-octane level, which makes these
compounds good for gasoline blending stocks, other toxicity issues limit their concentration
in present fuel specifications to about 3 wt%. Current work in this area is focused on a
number of improvements in hydrotreating catalysts with the following objectives:
• Optimize the catalytic processing for the properties of a given bio-oil or bio-oil
fraction feedstock
• Explore the efficiency and selectivity of these newly developed, non-sulphide
catalysts, which can be operated at lower temperatures
• Direct the selectivity to produce de-oxygenated higher value (but less
aromatic) transportation fuels in addition to chemical co-products
• Improve the hydrogen utilization for the process [8]

32. `29
5.7 Bio crude Oil Burner
Figure 10 Schematic of the biocrude-oil burner setup. [14]
The burner system was composed of the burner unit, combustion chamber, fuel tank, air
compressor, and flow control units for fuel and air as shown in Fig. 11. In the biocrude-
oil burner, the selection of the fuel nozzle is important due to its high viscosity. The solid
residue also has the potential problem of nozzle clogging during burner operation. In the
atomizing nozzle for the conventional oil burner, the liquid fuel is discharged under
pressure, resulting in high exit velocity from the fine orifice. In this nozzle type, the
spray formation of biocrude-oil would be difficult. Therefore, in this study, an air
atomizing spray nozzle with a much larger nozzle diameter than the general one was
adopted to atomize biocrude-oil. It is an external mix-type nozzle that is more effective
for higher-viscosity liquids. [14]

33. `30
6 Case Study
Table 8 List of Pyrolysis reactors all over world and its capacity [4]
Reactor Design Capacity(Dry
Biomass Feed)
Organization or
Company
Products
Fluidized Bed 400Kg/hr (11 tons
per day)
DynaMotive, Canada Fuels
250 kg/hr (6.6 tons
per day)
Wellman, UK Fuels
20 kghr (0.5 tons per
day)
RTI, Canada Research / Fuels
Circulating Fluidized
Bed
1500 kghr (40 tons
per day)
Red Arrow, WI
Ensyn design
Food flavouring /
Chemicals
1700 kghr (45 tons
per day)
Red Arrow, WI
Ensyn design
Food flavouring /
Chemicals
20 kghr (0.5 tons per
day)
VTT, Finland
Ensyn design
Research / Fuels
Rotating Cone
200 kg/hr (5.3 tons
per day)
BTG, Netherlands Research / Fuels
Vacuum
3500 kg/hr (93 tons
per day)
Pyrovac, Canada Pilot scale
demonstration / Fuels
Other Types 350 kg/hr (9.3 tons
per day)
Fortum, Finland Research / Fuels
6.1 Solar Assisted Pyrolysis
1. The experimental setup for solar pyrolysis of biomass is depicted in Fig. 11. In this vertical
axis solar furnace, the sunlight is first reflected by the heliostat and then concentrated by the
2 m dia. parabola. A transparent Pyrex balloon reactor with a 185 mm diameter (6 L volume),
set at the focus, is swept with an argon flow controlled by a mass flow meter (Bronkhorst,
EL-FLOW®
). The sweeping gas is used to provide an oxygen-free environment, and it also
keeps the reactor walls clean. The sample temperature is measured online by a previously
calibrated ―solar-blind‖ optical pyrometer (KLEIBER monochromatic at 5.2 mm), which
aims the sample through a fluorine window (transparent at this wave-length). The pyrometer
was calibrated using blackbody radiation, and the sample temperature was validated by
comparison with a K-type thermocouple measurement. The biomass pellet is set in a graphite
crucible that is put on a 1-cm thick graphite foam layer for reducing as much as possible the
temperature gradient in the biomass sample. Indeed, a water-cooled sample holder maintains
the sample at the focus of the solar furnace. Another piece of graphite foam layer prevents
radiative heat losses on the crucible sides. A shutter, made of composite carbon blades, is set
on the reflected solar beam before its concentration. The target heating rate and final
temperature are set on a PID controller, which controls the shutter opening based on the
sample temperature measured by the pyrometer. A needle valve set on the gas outlet tubing is

34. `31
used to regulate the reactor internal gas pressure constant as 0.52 bar. Finally, a vacuum
pump and a gas washing filter unit are set downstream the needle valve. When samples are
wanted, gaseous products are aspirated by a vacuum pump (the water content is removed by
the gas washing filter), and collected in a sampling bag for analysis in a micro gas
chromatograph. The gas sampling time is always 5 min throughout the pyrolysis process. On-
time IR gas analysis of the exhaust gas has shown that the re-action is complete after this
time for all experimental conditions. [10]
Figure 11 Experimental Setup

35. `32
6.2 Fixed Bed Tubular Reactor
In this study, the slow, fast and flash pyrolysis of rape seed were investigated in three
different reactors, namely, Heinze reactor, well-swept fixed-bed tubular reactor and tubular
transport reactor. Particularly, the influence of final pyrolysis temperature, heating rate, and
particle size range and sweep gas velocity on the product yields was studied.The slow
pyrolysis experiments performed in the Heinze reactor were carried out in two groups,
namely, self-pyrolysis and sweeping gas atmosphere.
The 316 stainless steel Heinze retort defined previously had a volume of a 250 cm3
(54 mm
i.e.) and was externally heated by an electric furnace with the temperature being controlled by
a thermocouple inside the bed. The connecting pipe between the reactor and the cooling
system was heated to 400ºC to avoid condensation of tar vapor. In the first, to determine the
effect of pyrolysis temperature on the yields of rapeseed pyrolysis, 10 g of air-dried sample,
– 0.85 mm size, was placed in the reactor and the temperature was raised with 30ºC
min 1
to final temperature of either 400, 500, 550, 600 or 700ºC and held for either a
minimum of 30 min or until no further significant release of gas was observed. The flow of
gas released was measured using a soap film for the duration of the experiments. The liquid
phase was collected in a glass liner located in a cold trap maintained at about 0ºC. [11]
Figure 12The yields of slow pyrolysis products at particle size of 0.425– 0.85 mm [11]
The fast pyrolysis experiments were conducted in a well-swept, resistively-heated, fixed bed
reactor (8 mm i.d., 90 cm h), but compared to the Heinze retort much faster heating rate of
300ºC min 1
was employed and the effect of pyrolysis temperature, particle size and sweep
gas velocity on the pyrolysis yields were examined. The sample were heated to the final
temperature of 400, 500, 550, 600 or 700ºC and held at that temperature for 30 min or until
no further significant release of gas was observed. To determine the effect of pyrolysis
temperature on the pyrolysis yields, the experiments have been conducted with heating rate of
300 º C min 1
, particle size range of 0.425– 0.85 mm, increasing the pyrolysis temperature from
400 to 700  C, the char yield decreased from 27.0 to 14.5%.In other words, the conversion increased

36. `33
from 73.0 to 85.5%. The oil was 36.8% at pyrolysis temperature of 400º C; it appeared to go
through a maximum of 63.1% at final pyrolysis temperature of 550 º C. Then, further
increasing the final pyrolysis temperature to 700 º C, the oil yield goes down to 57.5% [11]
Figure 13 – 0.85 mm [11]
The flash pyrolysis experiments were also conducted in a tubular reactor under nitrogen
atmosphere. The reactor with a length of 70 cm and an inner diameter of 1.2 cm was heated
externally by an electric furnace. In the reactor, the temperature was measured with
thermocouples at three different points. Concurrent nitrogen flow was used as a sweeping gas
measured by a rotameter. The pyrolysis experiments conducted in a flash pyrolysis reactor to
investigate the influence of residence time on the particularly oil yield. Fig. 14 shows the
product yields from the flash pyrolysis of rapeseed in relation to final pyrolysis temperatures
at 400, 500, 550, 600 and 700 º C for particle size range of 0.6– 1.25. [11]

37. `34
Figure 14 the yields of flash pyrolysis products at pyrolysis temperature of 550 º – 1.25 mm
[11]
In other words the char yield decreased from 31 to 14%. The oil was 58% at pyrolysis
temperature of 400 º C. As the temperature increased from 400 to 550 º C, the amount of
condensable liquid product increased from 58 to 72%, it appeared to go through a maximum
of 73% at final pyrolysis temperature of 600 ºC. Then, increasing the final pyrolysis
temperature to 700 º C, the oil yield goes down to 68% (Fig. 14). It can be easily seen that the
temperature of 550– 600 ºC is the convenient pyrolysis temperature. [11]
6.3 Pyrolysis in Fixed Bed Tubular Reactor
Figure 15 Fixed Bed Pyrolysis System [12]

38. `35
Pyrolysis was carried out in a fixed bed tubular reactor of length 102 cm and diameter
10.5 cm (Figure 1) under nitrogen atmosphere of 30 mL/min and reaction temperature of
600˚C. This condition has been established in our previous studies [19]. The reactor was
heated electrically at heating rate of 30˚C/min. 30 g of biomass sample (2 - 4 mm particle
size) was used in each experiment. The reaction time was kept at 15 min (±2 min) or
until no significant amount of non-condensable gas was observed. The pyrolysis vapor
was condensed in a condenser connected to chiller with cooling water at 4˚C and the oil
was collected for further analysis. Non-condensable gas was passed through a gas
scrubber and the dried gas composition was analyzed. Bio-char was collected at end of
each experiment after the reactor temperature cool to room temperature and further
analyzed.
Bio -oil, bio-char and non-condensable gas yield were between 29.56 - 34.26 wt%, 29.43
- 38.45 wt% and 31.32 - 37.47 wt% respectively. The bio-oil was acidic (pH: 2.92 - 3.2),
highly oxygenated (58.47 - 59.85 wt %) and had high moisture content between 39.28 -
43 wt%. The higher heating value of the oil was between 19.24 - 21.92 MJ/kg. [12]

39. `36
7 Conclusion
1. Pyrolysis process was studied from the literature and it was noted that for getting
maximum yield of bio oil the reaction rate should be higher i.e. minimum 10 C/s and
the pyrolysis temperature should be raised up to 550°C.
2. Various Reactor designs were studied for achieving fast pyrolysis and slow pyrolysis
process.
3. Bio Oil properties were studied from the literature.
4. Various applications of bio oil have been quoted in this report which has good
potential for becoming a fuel for future.

40. `37
8 References
1. Anil Kumar, Nitin Kumar, Prashant Baredar, Ashish Shukla. A review on biomass
energy resources, potential, conversion and policy in India. Renewable and
Sustainable Energy Reviews 45 (2015); 530–539.
2. P. Basu, Biomass gasification and pyrolysis practical design, 1st
ed., AcademicPress,
Kidlington, Oxford, 2010.
3. http://www.nrel.gov/ National Renewable Energy Laboratory website; date
17/10/2015
4. Hofmann, L.; Antal, M.J. Numerical simulations of the performance of solar fired
flash pyrolysis reactors. Sol. Energy1984, 33, 427–440
5. Hiloidhari M, Das D, Baruah DC. Bioenergy potential from crop residue biomass in
India. Renewable and Sustainable Energy Reviews 2014; 32: 504-512.
6. Biomass Energy in India: Transition from traditional to modern. The Social Engineer,
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7. N.H. Ravindranath, H.I. Somashekar, M.S. Nagaraja, P. Sudha, G. Sangeetha, S.C.
Bhattacharya, P. Abdul Salam: Assessment of sustainable non-plantation biomass
resources potential for energy in India. Centre for Sustainable Technologies, Indian
Institute of Science, Bangalore, India
8. Large Scale Pyrolysis Oil Production: A Technology Assessment and Economic
Analysis M. Ringer, V. Putsche, J. Scahill. Technical Report NREL/TP-510-37779
November 2006.
9. Optimization of Free Fall Reactor for production of Fast Pyrolysis Bio-Oil. C.J.
Ellens, R.C. Brown. Bioresource Technology 103(2012) 374-380
10. Product distribution from solar pyrolysis of agricultural and forestry biomass
residues Rui Li a
, Kuo Zeng a
, Jose_ Soria b
, German_Mazzab
, Daniel Gauthier a
,
Rosa Rodriguez c
, Gilles Flamant. Renewable Energy 89 (2016)27e35
11. Slow, fast and flash pyrolysis of rapeseed OzlemOnay∗, O. Mete Kockar Renewable
Energy 28 (2003) 2417–2433
12. Journal of Power and Energy Engineering, 2015, 3, 185-193 Published Online April
2015 in SciRes. http://www.scirp.org/journal/jpee
13. Biofuels production through biomass pyrolysis-A technological review Mohammad I.
Jahirul, Mohammad G. Rasul, Ashfaque Ahmed Chowdhury Energies 2012, 5, 4952-
5001; doi:10.3390/en5124952
14. Characteristics of flame stability and gaseous emission of biocrude-oil ethanol blends
in a pilot-scale spray burner Sang Kyu Choi a, b, Yeon Seok Choi a, b , Seock Joon
Kim a, b , Yeon Woo Jeong a
1.2.