PYROLYSIS OF BIOMASS
Thermal decomposition of solid waste (e.g., woody biomass or agroresidue) in an inert atmosphere or with insufficient oxygen to cause
partial oxidation (to provide the heat for decomposition) is called
pyrolysis. Depending on the rate of heating, final temperature reached,
a mixture of gas, liquid and remaining solid are the products.
Pyrolysis processes are carried out for (i) to produce char-coal and (ii)
To produce pyrolysis-oils (BIO-OIL), which may be processed into
EFFECT OF HEATING BIOMASS IN AN INERT ATM
Products: mixture of gas liquid and solid
Gas: A fuel about 20-25 % of the input mass.
Liquid: Tar + Aqueous solution +Oil
Factors which affect amount and quality of products:
COMPOSITION OF BIOMASS, RATE OF HEATING &
FINAL TEMPERATURE REACHED
HIGHER THE HEATING RATE & FINAL TEMP,
HIGHER THE CONVERSION TO GAS AND
HIGHER THE CARBONIZATION OF THE CHAR
WOOD + HEAT
WOOD CHAR +GAS
Thermal decomposition begins at about 100- 150 o C, increases with rising
temperature .At about 270 o C, exothermic reactions set in with a rise in
temperature (usually held at 400-500 o C) bringing about complete
carbonization. The products are charcoal, condensable liquids, and noncondensable gases.
C6n[H2O]5n 6nC +5nH2O
H2O CO + H2
+ 2H2 CH4 + CO2
2H2O CO2 + 2H2
FACTORS AFFECTING CHARCOAL QUALITY AND YIELD:
Apart from the moisture content of the wood charge, the type of wood and
its chemical composition, the charcoal properties depend significantly upon
the carbonization temperature. At lower temperatures the yield is high but
carbon content is low.
ULTIMATE ANALYSIS OF WOOD AND CHAR: TEMP: 400 o C:
(PINE SAW DUST AND BARK CHARCOAL)
It is seen that compared to wood the char has higher carbon content, heating
value increases and oxygen and hydrogen content decreases. Ash content
increases slightly and char is a more reactive fuel free from moisture.
H H V, KJ/Kg
EFFECT OF TEMPERATURE IN PYROLYSIS OF WOOD (on S-LG-- product distribution):
With increase in temperature the relative amount of char and condensable
liquid fraction keeps decreasing and gas formed increases.
1. „Fast Pyrolysis Processes For Biomass‟, Bridgewater A.V. and Peacocke
G.V.C, Renewable and Sustainable Energy Reviews 4(1): 1-73 (2000)
2. Progress in Biomass Conversion, Volume 3 edited by K.V. Sarkanen,
D.A. Tillman and E. C. Jahn, Academic Press, „Chapter on Chemistry of
Pyrolysis and Combustion of Wood „, pp 51-50. (1982)
3. Pyrolysis Oils from Biomass: Producing, Analyzing and Upgrading - ACS
Symposium Series 376, Edited by Ed. J. Soltes and Thomas. A. Milne,
American Chemical Society, Washington D.C., 1988. [662.8—76582]
Successful production of Bio Oil made from sugar cane bagasse. [Ref:
Electrical India 40 (18): 39, 2000]
The production run of Bio Oil made from sugarcane bagasse using the
patented Bio Oil pyrolysis technology has been successfully completed by
Dyna Motive Technologies Corporation in its pilot plant in Vancouver. The
patented technology converts low value forest and agricultural wastes into
liquid fuel. A commercial Bio Oil production plant processing 100 tonnes of
dry bagasse per day will produce approximately 22000tonnes of Bio Oil per
annum displacing 10.3 million liters of diesel oil and providing 30000 tons
of greenhouse-gas credits. Unlike fossil fuels, Bio Oil is clean burning, low
in SOx and NOx emission, is greenhouse gas neutral. It can be produced
economically from renewable biomass waste materials.
Pyrolysis for Pyrolytic oils:
Products of pyrolysis of wood are charcoal (25), wood gas (45%),
pyroligneous acid (45%), and tar or wood-oil. (15%) excluding the moisture
content, the last two liquid products being obtained by condensation of
volatiles from the wood. Both liquid and gas product of pyrolysis are
combustible and are potential fuel feedstocks.
Biomass fast pyrolysis is a thermochemical process that converts
feedstock into gaseous, solid, and liquid products through the heating of
biomass in the absence of oxygen. To produce transportation biofuels via
this thermo-chemical process, fast pyrolysis is followed by bio-oil
upgrading. Bio-oil is upgraded to naphtha-range and diesel-range distillation
fractions (gasoline blend stock and diesel blend stock, respectively,
hereinafter referred to as naphtha and diesel).
For modeling, the upgraded pyrolysis oil products are modeled as C8 and
General processing steps include biomass pretreatment, fast pyrolysis, solids
removal, bio-oil collection, char combustion, and bio-oil upgrading.
An overall description of the biomass fast pyrolysis process to produce
naphtha and diesel is shown in Figure. The hydrogen production scenario
employs optional equipment to generate requisite hydrogen. Biomass with
25% moisture content is dried to 7% moisture and ground to 3-mm-diameter
size prior to being fed into a fluid bed pyrolyzer operating at 480°C and
atmospheric pressure. Standard cyclones remove solids consisting mostly of
char particles entrained in the vapors exiting the pyrolyzer. Vapors are
condensed in indirect contact heat exchangers, yielding liquid bio-oil that
can be safely stored at ambient conditions prior to upgrading to
transportation fuels. Non-condensable gases are recycled to the pyrolysis
reactor after being combusted to provide process heat. This analysis assumes
that pyrolysis solid products are sent to a combustor to provide heat for the
drying and pyrolysis process. Excess solids consisting of char are sold as a
low-heating-value coal substitute. Bio-oil upgrading, which requires
hydroprocessing section, generates fuel compatible with existing
The upgrading process considered in this study is bio-oil hydrotreating and
hydrocracking. Hydrotreating and hydrocracking (hydroprocessing) are
commonly employed in the petroleum industry to remove undesired
compounds such as sulfur from crude oil and to break large hydrocarbon
molecules to produce clean naphtha and diesel. Bio-oil typically contains
significant quantities of oxygenated compounds that are undesirable for
combustion in vehicle engines. Hydrotreating can convert oxygen found in
bio-oil to water and carbon dioxide molecules, leaving hydrocarbons that are
suitable for internal combustion engines. Complex hydrocarbon compounds
are found in bio-oil, and hydrocracking is a potential method to decompose
these heavy compounds into naphtha and diesel.
The purpose of the assessed process is to convert biomass into liquid fuels
suitable for transportation applications. This is achieved by converting
biomass into bio-oil, which is subsequently upgraded to transportation fuels.
Design-basis model employs nine distinct sections as described in Table 1.
Biomass pyrolysis generates a large variety of organic and inorganic
compounds that make modeling efforts difficult. Hundreds of compounds
have been identified in bio-oil— the primary fast pyrolysis product . A
common approach is to employ model compounds to represent chemical
groups based on their significance and quantity. This model adapts pyrolysis
oil and gas composition from research by NREL as described in the
“Pyrolysis” section of this report .
Two models are developed to study the performance of biomass pyrolysis
for different scenarios: a hydrogen production scenario employing bio-oil
reforming to generate requisite hydrogen for bio-oil upgrading, and a
hydrogen purchase scenario using merchant hydrogen for bio-oil upgrading.
Pyrolysis is a flexible process that can be designed with numerous
configurations and scaled to various capacities.
Hydrogen production fast pyrolysis and oil upgrading employs a portion of
the bio-oil produced to generate the required hydrogen for oil
hydroprocessing. Additional equipment, including a reformer and gas
compressor, are required by the hydrogen production system. The second
scenario forgoes the additional investment by purchasing hydrogen from a
remote source. Scenarios are based on 2,000 MT/day corn stover input.
Fast pyrolysis of biomass is a thermal process that requires temperatures
near 500°C, rapid heat transfer, and low residence times. Various reactor
designs have been proposed for this process . Because of concerns over
the scalability of existing reactor designs, this study assumes that multiple
500 MT/day reactors are employed in parallel. This size is selected based on
assumptions from a report by NREL . Commercial units as large as 200
MT/day are currently in operation. Pyrolysis product distribution is adapted
from USDA data  using the bio-oil and non-condensable gas (NCG)
composition shown in Table 6. Bio-oil and NCG composition is modified
from a previous NREL analysis . Bio-oil compounds are selected based
on available Aspen Plus software compounds and may not share the same
properties as compounds selected by NREL. Table 5 shows various
pyrolysis yields for corn stover [14, 26]. Table 6 includes the initial
pyrolysis product yields employed in this study. The final yield is adjusted
to ensure mole and mass balance.
COMMERCIAL BIO-OIL PRODUCTION
VIA RAPID THERMAL PROCESSING
Mr Barry Freel, Dr Robert Graham
Ensyn Group Inc.
20 Park Plaza, Suite 434
Boston, MA 02116, USA
11 December, 2000
ABSTRACT: Ensyn has successfully developed a commercial biomass refining
business, based on the commercial production of bio-oil and the use of bio-oil for the
subsequent production of value-added natural chemical products and fuels. After ten
years of commercial operations and with a number of commercial facilities in
operation, Ensyn has embarked on a significant expansion of its activities.
Ensyn's core technology in the biomass sector is the Rapid Thermal Processing
or RTP™ process, which consists of a proprietary system for the fast thermal
conversion of wood and/or other biomass to high yields of a light, liquid bio-oil,
for the subsequent extraction and manufacture of natural chemical products and
bio-fuels. Ensyn's RTP™ technology, the world's only commercial fast
pyrolysis technology, is the foundation of a new and exciting biomass refining
industry. In the biomass refining concept, value-added chemical products are
first recovered from bio-oil, and the remaining liquid bio-oil is then used for
fuel and power (bio-energy) applications. Ensyn has pioneered the development
of the biomass refining industry through the development of a proprietary,
commercial, fast pyrolysis technology and, in parallel, the development of a
number of value-added natural chemical products and bio-fuels sourced from
RTP™ bio-oil and related by-products.
Ensyn's RTP™ technology has been under continuous development by Dr
Robert Graham and Barry Freel, (Ensyn's President & CEO and VP & Chief
Technology Officer, respectively) since 1980. The RTP™ name was first
established in 1984. The first process patent related to RTP™ issued in 1991,
and subsequent process patents issued in 1994 and 1999. A number of
additional product patents have issued. The key patents are all held by Ensyn
Group Inc. or its 100% controlled subsidiaries. Commercial sales of RTP™
equipment and/or RTP™ bio-oil products were initiated in 1989.
The Company's principal design, engineering and R&D operations are located
near Ottawa, Ontario.
There are presently four (4) RTP™ plants in commercial operation. A new
commercial RTP™ plant and a bio-oil refining plant are currently under
Ensyn's RTP™ technology is based on the biomass refining concept, in which
high yields of a consistent quality bio-oil are produced, and value-added
chemical products are recovered and/or manufactured from the bio-oil, before
the remaining liquid bio-oil is used for fuel and power (bio-energy)
applications. Ensyn currently produces approximately 30 chemical products
from whole RTP™ bio-oil, and these are sold in commercial applications
related to the food, polymer/co-polymer, petrochemical and natural chemical
3. BUSINESS MODEL
Ensyn's business model in biomass activities is based on the ownership and
operation of production facilities in which value is maximised by optimising
multiple product streams available from the pyrolysis of biomass feedstocks.
This model is typically based on the extraction of higher-value natural chemical
products from RTP™ bio-oil, and the use of remnant bio-oil for lower value
energy purposes. In addition, the char is a high quality, consistent product which
may be consumed for energy in the process itself, sold as is, or activated for
higher-value applications. The combustible byproduct gas is normally used
internally for RTP™ process heat. In typical biomass applications, Ensyn does
not supply its equipment to third parties, nor does it license others to use its
4. NATURAL CHEMICAL PRODUCTS
Ensyn has been producing commercial quantities of chemical products from its
RTP™ bio-oil since 1991. Early commercial production of chemical products
was focused primarily on the food industry. More recently, Ensyn has
introduced a range of polymer and co-polymer products. The polymer/copolymer products represent newer markets for Ensyn, but these sectors represent
far greater growth potential.
Ensyn recently entered into a joint development program with Louisiana Pacific
Corp., the leading US wood products manufacturer, for the development of
adhesive products from bark wastes; this program was awarded a grant of
US$1.4 million from the US Department of Energy. In addition, Ensyn is
working with other leading companies in the wood and industrial adhesive
markets in the development and application of various adhesive products made
from RTP™ bio-oil. The use of these natural products from RTP™ bio-oil
presents users with attractive advantages including cost, performance and
environmental benefits. The environmental benefits include replacement of
fossil-fuel chemicals in adhesive formulations, waste biomass remediation, and
possibly CO2 credits.
5. ENERGY APPLICATIONS
In addition to natural chemical products, Ensyn has developed a number of
actual and potential energy applications for its bio-oil. These include the use of
RTP™ bio-oil in boilers, stationary drivers (i.e., engines, turbines) and as a fuel
component in transport applications. A number of initiatives are under way in
these areas which are confidential. As petroleum prices rise and environmental
impact costs are accounted for, there are clearly a number of interesting
opportunities for Ensyn bio-oil in the energy markets. In particular, reference is
made to those energy markets that have fiscal incentives for renewable energy,
CO2-neutral fuels, and low sulfur fuels. It is possible that in the future Ensyn
will establish RTP™ facilities which are 100% bio-fuel related. Nevertheless,
under present market conditions, we believe that the most attractive economics
are in adopting a refining approach to this industry, based on the extraction of
higher-value natural chemical components first, and the use of remnant bio-oil
in lower value applications such as fuels.
6. RAPID THERMAL PROCESSING
Ensyn's RTP™ technology has represented a true breakthrough in biomass
thermal conversion. It is the world's first and only proven commercial biomass
fast pyrolysis technology. In the Ensyn RTP™ process, wood or other biomass
material is fed into a heated vessel where it is contacted with a stream of hot
sand. There is essentially no combustion occurring in this vessel since air input
is minimized. At a temperature of around 500°C, much lower than combustion
or gasification, the turbulent hot sand instantly flashes the biomass into a vapor,
which is then cooled, condensed and recovered as a liquid product.
RTP™ is fast pyrolysis. The processing time, including the time the feedstock is
in the reactor and until the product gases and vapors are quenched, is typically
under two seconds. The reaction takes place at atmospheric conditions at
moderate temperatures. At the heart of the RTP™ technology is the unique
ability to produce a consistent, light bio-oil, in high yields, from wood and other
biomass in commercial operations.
7. BIOMASS FEEDSTOCKS
Ensyn processes both hardwoods and softwoods, and both white wood and bark.
In addition, Ensyn's RTP™ processes bagasse and various additional (nonpublished) biomass feedstocks for the production of specific natural chemical
Commercial bio-oil yields average 75%. This is the liquid bio-oil yield. The
balance is approximately 13% char and 12% combustible gas. These yields are
by mass-weight, and are as a percentage of dried wood (approximately 8%
9. EXISTING FACILITIES AND EXPANSION PLANS
Ensyn has four commercial RTP™ facilities currently in operation, three in
Wisconsin and one in Ottawa, Ontario. These are currently the only fast
pyrolysis plants in the world operating commercially. The largest of these
processes 75 green tons per day of mixed hardwood wastes (i.e., equivalent to
around 40 tons of dried wood going to the RTP™ unit). This RTP™ facility
was built in Wisconsin by Ensyn in 1996, and has operated with a commercial
availability of over 94%. Ensyn produces more than 800 tons of bio-oil per
month in Wisconsin.
In addition to the commercial facilities, Ensyn currently operates two research
RTP™ facilities, both based in Ottawa.
Ensyn has recently initiated engineering and
construction of a new commercial 40 dry ton per day
RTP™ unit, in addition to a new bio-oil processing
facility. The new RTP™ unit is due to be
commissioned by September, 2001 and the processing
facility is to be commissioned by February,
2001.These expansions will allow Ensyn to meet
commercial delivery commitments of a new polymer
compound for a major US chemical company as well
as to increase its deliveries of current commercial
products for the food industry.
This RTP™ facility in
Wisconsin processes 70
green tons of wood residues
per day. Ensyn's biomass
produce over 800 tons of biooil per month.