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Pyrolysis of biomass

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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, 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



                                                         1
                  SLOW PYROLYSIS
        WOOD + HEAT             WOOD CHAR
     +GAS

Thermal decomposition begins at about 100- 150 oC,
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.

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.



                                                           2
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.




                                                           3
                Temp.oC Char     Lqd.     Gas
                        %    dry %    dry %    dry
                        feed     feed     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 – 105 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

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.

POTENTIAL AVAILABILITY OF AGRORESIDUE: INDIA
(1995-96)
MT = Million tons


                                                           4
             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
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]




                                                            5
                          Pyrolysis

         Fast pyrolysis for liquid is less developed than
gasification but offers the considerable advantage of a liquid
product that can be stored or transported, i.e. de-coupling
the conversion technology from the utilisation of the product.
As with gasification the system has to be considered in
totality and the component needs and system needs are
identified and described. The heart of the fast pyrolysis
process is the fast pyrolysis reactor. Many types are
currently operational and no best method has emerged.
Indeed, further innovation should be expected, with new
concepts and both radical and minor modifications to
reactors to reduce costs, improve yields, improve product
quality and improve ease of scale up.

The use of catalysts to enhance the pyrolysis process and
improve the product quality is likely to increase. A key
feature of further development will be increasing attention on
the fundamentals of pyrolysis - modelling, design,
mechanisms etc. which are essential for further process
improvement and optimisation.

Product collection

Efficient collection of the liquid product in terms of yield and
product quality is still a major problem. Heat exchange is not
sufficient by itself as the product is largely in aerosol form
which, like cigarette smoke, is very difficult to capture.
Quenching and electrostatic precipitation are currently the
preferred options, but there is a need to design more

                                                               6
effective and efficient devices. Selective condensation or
fractionation can be explored again to improve product
quality and possibly enhance yields of chemicals.

In addition to collection problems, there is the problem over
char in the product which is too small to be collected in the
cyclones and accumulates in the liquid. This can be removed
by hot vapour filtration which affects product yield and quality
or by liquid filtration or centrifugation which is difficult and
gives high losses. The third option is to adapt the application
to accept liquid with a significant char content. All these
solutions have advantages and disadvantages and require
further R&D and subsequent evaluation to identify the
preferred route.

Product characterisation and quality

Pyrolysis liquid is a fuel oil but with significantly different
characteristics from conventional fuel oils in that it is water-
miscible and relatively unstable through viscosity changes
and occasionally phase separation and is temperature
sensitive. The important characteristics for each potential
application need to be defined and steps taken to satisfy
requirements such as by addition of modifiers or enhancers.
Characterisation of this liquid is difficult and standard fuel
tests may not be appropriate. New tests may have to be
developed to measure key parameters including stability in
particular. Chemical analysis is complex from the wide range
of different functional groups and the very large number of
individual chemicals. Analysis is important to aid process
analysis and hence process optimisation and requires

                                                               7
continued support to ensure that ongoing research projects
are properly supported.

Product modification:

Upgrading to a product that is compatible with conventional
fossil fuels will remain of interest even though the chemistry
and economics of the conversion of biomass or bio-oil, with
its high oxygen content, to hydrocarbons with no oxygen, is
not easy. Upgrading by hydro-processing type methods to
hydrocarbons and transport fuels is technically successful
but uneconomic due to the hydrogen requirement and high
pressure processing. Zeolite cracking is potentially more
interesting as low pressure is required without any hydrogen
and the process is integrated into the fast pyrolysis process,
but yields are lower and a more complex integrated catalytic
regenerative process is needed. This makes useful research
difficult to perform in small scale laboratory systems. This
area of integrated catalytic pyrolysis is deserving of further
study for process and product optimisation. The stability
problems that have been reported with the liquid are
believed to be caused by polymerisation/condensation type
reactions between carbonyl groups in aldehydes for example
and the phenols in the acid environment. Modification of the
more reactive functions in the liquid would lessen or
minimise such reactions. This is being studied through
modification of the pyrolysis process either within the reactor
or close coupled, and also by modification of the liquid after
its production. Neither route yet has enough results to offer
guidance. The interface between fast pyrolysis and the liquid
product application needs more careful assessment for a

                                                              8
variety of topical applications so that the bio-oil requires
minimum modification.

Applications

Heat:
Combustion of pyrolysis liquid has been successfully
demonstrated but problems remain with handling and
stability, start-up and shut-down, atomisation, emissions, co-
firing with other fuels, although some success has been
reported with emulsions, flame temperatures and patterns.

Power:
Both engine and turbine show promising results with some
improvements over conventional fuels but require long term
operation and optimisation in order to assess corrosion,
deposits and offer warranties. The anticipated problems of
instability etc. have not materialised.

Chemicals:
Chemicals offer the high value-added opportunities that this
industry requires to be viable in the short term. The markets
require development however, both for product substitution a
well as new products.

System:
It is important to consider the complete system in terms of
energy integration and utilisation of the gas and char by-
products.




                                                             9
Conclusions on pyrolysis:

Fast pyrolysis offers the unique advantages of a liquid that
can be stored and/or transported and which can be used for
fuel and/or chemicals production. There are still many
challenges to be met including provision of consistent bio-oil
in sufficient quantities for thorough testing in various
applications, scale-up of fast pyrolysis processes with
concomitant cost reductions from process development, and
development of norms and standards for the liquid product
particularly in terms of quality so that it can be marketed
successfully.

Publication: The 550 page hardcover book of proceedings is
available (price 150 eu) direct from CPL Scientific Ltd (CPL
Press) or from normal bookshops or other outlets for EC
publications (ISBN 1 872691 71 4, EUR 17788) as Biomass
Gasification and Pyrolysis, M Kaltschmitt and A V
Bridgewater eds, 1997.




                                                            10
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.




                                                            11
Pyrolysis for Pyrolytic oils:
Ensyn - News and Information

    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.

 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.

                                                                12
       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 construction.


                                                          13
      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.

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 technology.




                                                            14
 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.

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

                                                              15
 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.

       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


                                                             16
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.

     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.

      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).

     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

                                                                 17
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 initiated engineering and construction of a
new commercial 40 dry ton per day RTP™ unit, in addition to
a new bio-oil processing facility. 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.




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