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PYROLYSIS OF BIOMASS

Thermal decomposition of solid waste (e.g., woody biomass or agro-

residue) 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

liquid fuels.

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

Solid: Char

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 LIQUID

PRODUCTS,

HIGHER THE CARBONIZATION OF THE CHAR

SLOW PYROLYSIS

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 non-

condensable gases.

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CHEMICAL REACTIONS:

C6n[H2O]5n 6nC +5nH2O

Secondary reactions:

C + H2O CO + H2

2CO + 2H2 CH4 + CO2

C + 2H2 CH4

C + 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.

Element % Wood Char

C 52.3 75.3

H 5.8 3.8

O 38.8 15.2

N 0.2 0.8

S 0.0 0.0

ASH 1.4 3.4

H H V, KJ/Kg 19.7 27.1

EFFECT OF TEMPERATURE IN PYROLYSIS OF WOOD (on S-L-

G-- product distribution):

With increase in temperature the relative amount of char and condensable

liquid fraction keeps decreasing and gas formed increases.

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Temp.oC Char

% dry feed

Lqd.

% dry feed

Gas

% dry feed

500 29 53 18

600 24 52 24

700 20 50 30

800 17 47 36

900 15 40 45

1000 14 30 56

RAPID FLASH PYROLYSIS: 103 – 10

5

o C/ SEC

INTERMEDIATE PYROLYSIS: 10 – 100 o C/ SEC

SLOW PYROLYSIS: 0.1 –1 o C/ SEC

RAPID PYROLYSIS (FLUIDIZED BED) GAS PRODUCT

GIVES

OPTIMUM TAR

YIELD

POTENTIAL AVAILABILITY OF AGRORESIDUE: INDIA (1995-96)

MT = Million tons

Agro-residue India, MT T.Nadu, MT

Wheat Straw 83.3 9.2

Rice Husk 39.8 3.3

Maize Cobs 2.8

Pearl Millet straw 9 0.6

Sugar Cane Bagasse 93.4

Coconut shell 3.4 0.4

Coconut pith 3.4

Groundnut shells 2.6 0.6

Cotton Stalks 27.3 0.8

Jute Stalks 2.7

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References:

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.

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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

C10 hydrocarbons.

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

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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

infrastructure.

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.

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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 [16]. 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 [8]. 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.

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Pyrolysis

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 [25]. 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 [8]. Commercial units as large as 200

MT/day are currently in operation. Pyrolysis product distribution is adapted

from USDA data [14] 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 [8]. 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.

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11

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.

1. INTRODUCTION

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

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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

construction.

2. APPLICATIONS

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

industries.

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

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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

technology.

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/co-

polymer 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

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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.

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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 (non-

published) biomass feedstocks for the production of specific natural chemical

products.

8. YIELDS

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%

moisture content).

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.

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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

facilities in Wisconsin

produce over 800 tons of bio-

oil per month.