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0 | P a g e 0 9 C H 3 0 0 6 A m a n S i n h a l
DEPARTMENT OF CHEMICAL ENGINEERING,
INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR
(2012 2013)
PYROLYSIS OF MICROALGAE FOR THE PRODUCTION OF
RENEWABLE FUELS
Submitted in fulfillment of the degree of
Bachelor of Technology
In
Chemical Engineering
By
Aman SinhalRollNo.09CH3006
UNDER THE SUPERVISION OF
Dr . Saikat Chakraborty
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Certificate
This is to certify that the thesis entitled Pyrolysis of Microalgae for the production of Renewable
Fuels submitted by Aman Sinhal to the Department of Chemical Engineering, in partial
fulfilment for the award of the degree of Bachelor of Technology is an authentic record of the
work carried out by him under my supervision and guidance. The thesis has fulfilled all the
requirements as per the regulations of this institute and, in my opinion, has reached the standard
needed for submission.
Date: 01/05/2013
---------------------------------
Dr. Saikat Chakraborty
Department of Chemical Engineering
Indian Institute of Technology, Kharagpur
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Acknowledgement
I would like to extend my heartfelt gratitude to Prof. Saikat Chakraborty for providing me with
the opportunity to work on a project based on renewable energy source which is the need of thehour and is in the greater interest of the society. It is very difficult to describe her contribution to
the thesis in words.
I am thankful to Prof. N. C. Pradhan, Head of the Department of Chemical Engineering, IIT
Kharagpur and the faculty members of the department for their invaluable support and
encouragement. I am also thankful to Mr. Ankit Agarwal for providing important inputs for the
preparation of the report as it is in the present form.
Date: 1stMay, 2013 Aman Sinhal
Place: Kharagpur 09CH3006
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Abstract
Pyrolysis involves the simultaneous change of chemical composition and physical phase, and is
irreversible. It is a thermochemical decomposition of organic material at elevated temperatures without
the participation of oxygen. The word is coined from the Greek-derived elements pyro "fire" and lysis
"separating". In this work fast catalytic and non-catalytic pyrolysis of microalgae, Chlorella Vulgaris was
studied to generate third generation biofuel.
Fixed bed Pyrolysis reactor with the auger feed arrangement was designed to feed the biomass into the
hot-zone. Heterogeneous catalyst such as Ni-ZSM5 was prepared from pentasil using ion exchange with
Ni(NO3)2 to study the catalytic upgradation of biofuel from algae. To study the kinetics of pyrolysis of
microalgae, it was pyrolysed in the thermogravimetric analyzer from room temperature to 800 0C in inert
N2 atmosphere at different heating rates of 5,10,20,30,40 C/min.
The results showed that three stages appeared during the pyrolysis process and with increase in heating
rate, initial temperature, peak temperature and rate of conversion increases. The kinetic analysis of the
stage 2, where the major decomposition take place during pyrolysis was done using iso-conversional and
regression analysis methods. The activation energy of 51 KJ/mol and 49 KJ/mol was estimated using
Flynn and Kissinger iso-conversional methods respectively. The combustion characteristics of biomass
were also compared with pyrolysis in this study.
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Contents
ABSTRACT ........................................................ .............................................................. ........................... 2
CHAPTER 1:INTRODUCTION............................................................ ........................................................... 6
1.1OBJECTIVE OF WORK IN EACH OF THE PART........................................................ ........................... 9
CHAPTER 2:LITERATURE REVIEW................................................. ......................................................... 10
2.1REACTOR DESIGNS FOR PYROLYSIS............................................................................................ ... 11
2.2BIO-OIL................................................................ .............................................................. .............. 13
2.3FEEDSTOCK................................ ................................................................. .................................... 14
2.4TYPES OF BIO OILS............................................................................................................ .............. 14
2.5UPGRADING AND STABILITY OF BIO-OIL.................................................. .................................... 15
CHAPTER 3:EXPERIMENTAL SETUP.................................................................... .................................... 16
3.1EXPERIMENTAL PROCEDURE........................................................................................... .............. 19
3.2SELECTION OF CATALYST............................................................................................................ ... 20
3.3CATALYST PREPARATION PROTOCOL............................................................................. .............. 24
FIGURE 6:PROTOCOL FOR PREPARATION OF CATALYST,NI-ZSM5 ............................................... 25
3.4THERMOGRAVIMETRICANALYSIS................................................... .............................................. 26
3.5MATERIALS REQUIRED FOR EXPERIMENT................ ................................................................. ... 27
3.6METHOD OF EXPERIMENT......................................... ................................................................. ... 27
CHAPTER 4:ALGAL PYROLYSIS REACTOR MODELING........................................................................... 28
4.1DESCRIPTION OF EACH ZONE........................................................... .............................................. 29
4.2MODELING EQUATIONS.................................................................................................... .............. 30
4.3STEADY STATE MODELING TWO-PHASE CATALYTIC REACTOR (ZONE 3) ............................ ... 32
CHAPTER 5:SIMULATIONS (STEADY STATE) ........................................... .............................................. 34
CHAPTER 6:UNSTEADY STATE MODELING................................... ......................................................... 38
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CHAPTER 7:SIMULATIONS (UNSTEADY STATE) ........................................................... ......................... 41
CHAPTER 8:CONCLUSION...................................................................................... ................................... 49
8.1SUMMARY......................................................... ................................................................. .............. 49
8.2FUTURE WORK..................................... ................................................................. ......................... 50
APPENDIX............................................................. .............................................................. ......................... 51
REFERENCES........................................................................................................... .................................... 58
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Chapter 1: Introduction
In light of the degree of pollution that the environment has undergone in the last couple of
decades, it is only natural that we look for renewable sources of energy. With the population
explosion that the developing countries have resulted in, developing alternative sources of
energy like bio-fuels are the need of the hour. The most common bio-fuels are biodiesel and bio-
ethanol, which can replace diesel and gasoline, respectively, in today cars with little or none
modifications of vehicle engines. In this report, we focus on the catalytic and non-catalytic
pyrolysis, comparison and preparation of different catalyst used for thermal upgrading, kinetic
study of the pyrolysis process through thermo gravimetric analysis and have a detailed
model of the reactor system.
Figure 1: Sample of Algae
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The transportation and energy sector are the major sources of green house gas emissions. It is
expected that with the development of new growing economies, such as India and China, the
global consumption of energy will raise and lead to more environmental damage. One important
goal is to take measures in transport emissions such as gradual replacement of fossil fuel by
renewable energy sources, where bio-fuels are seen as real contributors to reach the goal in long
term. The most common bio-fuels are biodiesel and bio-ethanol, which can replace diesel and
gasoline. They are mainly produced from biomass or renewable energy sources and contribute to
lower combustion emissions. Beside renewable, biodiesel is also non toxic and biodegradable.
Several concerns have been raised about sustainability of this mode of production: to produce
2,500 billion liters of biodiesel from oilseed rape (i.e. the current demand of petroleum diesel in
the whole UK), 17.5 Mha would be required for plantation i.e. more than half the land area of
UK itself. Moreover, the overall savings in energy and greenhouse gas emissions if the lifecycle of
bio-fuel is considered as a whole are typically below what is normally anticipated; e.g. for
biodiesel from oilseed rape or soya, a lifecycle assessment indicates that ca. 50% of the energy
contained in the fuel will be spent in biodiesel processing itself. Biomass as a feedstock for bio-
fuel production should have a low price, minimum by products and waste, not compete with food
industry and grow fast with high solar yield.
Algae, growing microorganisms found in water, are such an option. Algae are a very promising
feedstock for the following reasons:
1. High growth rate (up to 20 g dry algae per m2 per day),
2. High yield per area (15 times higher than palm oil),
3. High efficiency in CO2 capture and solar energy conversion (wt%),
4. No competition with food agriculture.
5. They can be grown in open water and in bio-photo reactors on non-arable land.
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Algal biomass contains three main components - carbohydrates, proteins, and lipids. On an
industrial scale only few algae species are produced, and the most widely cultivated is
chlorella. From an economic point of view, fuel production from algae (or for that matter any
biomass) requires utilization of the complete biomass as efficiently as possible. Generally, bio-
fuel (bio-diesel) from algae is produced via extraction of lipids by organic solvents, e.g.
hexane, or by pressing of dry algae, followed by transesterification in methanol using basic
catalysts. The solid residue from the algae process contains minerals (up to 10%) which can
be fed back to the growth cycle. However, the rest 60% is waste [1], which makes the process
economically less attractive. For the high efficiency this process requires a special strain of
algae to be cultivated, which increase the cost of the raw material thereby making whole
process economy unviable at the industrial scale.
Alternative to the transestrification, pyrolysis of algae utilizes the complete organic part of
the biomass. Comparing the two processes the pyrolysis is simpler and produces the bio-oil
under moderate condition (450-500 oC). Pyrolytic oils are usually mixtures of oxygenated
components such as alcohols, ethers, aldehydes, ketones, phenols, esters, and acids. The
quality of pyrolysis bio-oil from biomass (both algae and other plants) is up to now far too
poor for direct use as transportation fuel or even for direct upgrading to fuel precursors at
existing oil refineries. It is very viscous, acidic (pH
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1.1 Objective of work in each of the part
Algal Pyrolysis: Experiments
I. Advance knowledge and understanding of an integrated pyrolysis-catalytic
upgrading system, where we seek to produce a stable liquid fuel from algae.
II. Preparation of different catalyst.
III. Pyrolysis of biomass and model compound to better understand the pyrolysis of
biomass.
Algal Pyrolysis: Modeling and Simulation
I. Modeling of the pyrolysis reactor system to study effect of different parameter of
the Bio-fuel yield.
II. Classifying the reactor into different zones and model equation for each of them.
III. Using TGA and pyrolytic experiment data, simulate the model equation for
concentration and temperature.
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Chapter 2: Literature Review
A detailed investigation of the mechanism of pyrolysis is a challenging task because numerous
intermediate substances are involved. Moreover, the chemical mechanisms are often affected and
influenced by physical phenomena like heat transfer, especially in the presence of particles of
different size classes. Such effects can be minimized in thermogravimetric investigations, hence
these are often used to derive global kinetic rate constants for pyrolytic processes.
There are generally three types of pyrolysis:
1. Conventional or slow pyrolysis
I. In slow pyrolysis there is high vapor residence time, slow heating rate leading to
the high yield of the gaseous and solid products.
2. Fast pyrolysis
I. Fast pyrolysis is a high temperature process in which biomass is rapidly heated
in absence of oxygen.
II. Fast pyrolysis has four essential features process:
a.very high heating and heat transfer rates are used which usually requires
a finely ground biomass,
b. a controlled pyrolysis reaction temperature,
c.short vapor residence times are used. Fourth, pyrolysis vapors and
aerosols are rapidly cooled to give bio-oil and
d. is controlled to give high liquid yields.
III. There are several different type of reactor used in research for pyrolysis
yielding largely varying product both in composition and yield.
3. Flash Pyrolysis
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2.1 Reactor designs for Pyrolysis
There is a huge variation in yield with change in the design of the pyrolysis. There are
generally three type of reactor employed in pyrolysis of microalgae.
1) Fluidized bed reactor
I. This reactor generally uses sand as heating medium for the feedstock.
II. Fluidized bed reactor is generally attached to a cyclone to separate char
from the solid product. Since the technology of this reactor is well
established most of the industrial scale experiments were done using
this type of reactor.
2) Fixed bed type reactor
I. It is simple in design but since the char is deposited at the bottom of the
reactor.
II. Since the char is heated, it may contribute to the secondary breaking of
the pyrolysis vapour. This is one of the major drawback of this type of
reaction.
III. This type of reactor is majorly used at laboratory scale to study the effect
of temperature, catalyst, feedstock and the other parameters affecting
the yield of the product.
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3) Microwave reactor.
I. Some of the latest research shows that another type of reactor i.e.
microwave reactor have a high efficiency in producing biofuel. In
microwave reactor there is much more uniform heating compared to
that of fixed or fluidized bed reactor.
II. Microwave heating is fundamentally difference from all other pyrolysis
techniques as the biomass particles are heated from within and not by
external heat transfer from a high temperature heat source .
III. In microwave reactor generally we require a receptor to absorb energy,
but in our case it has been found that char from the pyrolysis is itself a
very good microwave receptor which can be recycled for the use.
IV. Microwave reactor doesnt require any sweep gas to remove the gaseous
product from the reactor.
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2.2 Bio-oil
Pyrolysis oil sometimes also known as bio crude or bio-oil, is a synthetic fuel under investigation
as substitute for petroleum. It is extracted by biomass to liquid technology of destructive
distillation from dried biomass in a reactor at temperature of about 500C with subsequent
cooling.
Pyrolytic oil (or bio-oil) is a kind of tar and normally contains too high levels of oxygen to be a
hydrocarbon. As such it is distinctly different from similar petroleum products. It is composed of
a very complex mixture of oxygenated hydrocarbons with an appreciable proportion of water
from both the original moisture and reaction product. Solid char may also be present. The liquid
is formed by rapidly quenching and thus freezing the intermediate productsof flash degradation
of biomass. The liquid thus contain many reactive species, which contribute to its unusual
attributes. After cooling and condensation, a dark brown homogenous mobile liquid is formed
which has a heating value about half that of conventional fuel oil. A high yield of liquid is obtained
with most biomass feeds low in ash.
There are several factors affecting the composition of bio-oil, mainly feedstock composition,
reacting temperature, reactor design, and residence time. As a result, the critical issue is to bring
the reacting biomass particles to the optimum process temperature and minimize their exposure
to the lower temperatures that favour formation of charcoal, and high temperature which would
lead to the secondary reaction. Aging is a well-known phenomenon caused by continued slow
secondary reactions in the liquid which manifests as an increase in viscosity with time. Bio-fuel
need to be upgraded to be able to be used at commercial scale.
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2.3 Feedstock
There has been developed fast pyrolysis technology for maximizing liquid yields. However, most
of the research has concentrated on lignocellulosic materials such as pine wood, cotton straw and
stalk. But fast pyrolysis of microalgae that usually have higher photosynthetic efficiency, larger
biomass, faster growth compared to those of lignocellulosic is fastly getting attention.
Heterotrophic growth of C. protothecoides results in high production of biomass and
accumulation of high lipid content in cells. Applying this cell engineering to the fuel production
of fast pyrolysis, Heterotrophic culture not only can be used for improving the efficiency and
reducing the cost of biomass production but also can be used for efficient production of some
metabolites favourable for bio-oil production.
2.4 Types of Bio oils
Thermogravimetry is one of technique that has been employed study bio-oil fuel properties since
the mass losses measured by this method depend on the volatility (or molar mass) of the
fractions is investigated.
These materials are generally represented as:
1) 20 mass % of water
2) 40 mass % of GC-detectable compounds
3) 15 mass % of non-volatile HPLC detectable compounds
4) 15 mass % of high molar mass non-detectable compounds.
The grouping of bio-oil compounds in chemical families is very useful and necessary because
these materials can be treated as a mixture of few groups instead of hundreds of compounds.
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2.5 Upgrading and Stability of Bio-oil
Upgrading bio-oil to a conventional transport fuel such as diesel, gasoline, kerosene, methane and
LPG requires full deoxygenating and conventional refining by ways like:
1) Hydrotreating
2) Catalytic cracking
Hydro-processing rejects oxygen as water by catalytic reaction with hydrogen. The process is
typically high pressure (up to 20 MPa) and moderate temperature (up to 400 oC) and requires a
hydrogen supply or source. The catalysts originally tested in were based on sulfided CoMo or
NiMo supported on alumina or aluminosilicate and the process conditions are similar to those
used in the desulfuriszation of petroleum fractions. Full hydrotreating gives a naphtha-like
product that requires orthodox refining to derive conventional transport fuel. But there is a
substantial hydrogen requirement in all hydrotreating, processes to hydrogenate the organic
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Chapter 3: Experimental Setup
1) A Moving bed reactor is used to perform pyrolysis of algal feedstock.
2) An auger screw feeder was used to continuously feed microalgae particles, which fall
by gravity into the hot reaction zone set at a prescribed temperature.
3) The reactor system consisted of a 316 stainless steel tube (height=85 cm, diameter
=2.54 cm), gas pre-heater, condenser system and auger feeder. The microalgae
biomass particles were fed to a high temperature zone of the reactor.
4) Quartz wool and product char is supported by porous quartz fritz (25 micron) located
in the middle of the reactor.
5) Reactor temperature was measured using a Ni-Cr thermocouple which is used to
measure temperature as high as 1000 degree C.
6) The flow rate of the gas was controlled by a bubble flow meter.
Fig. 2(a) Feed Arrangement Fig. 2(b) Reactor inside the Furnace
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Fig. 2(c) View of Pyrolysis Reactor
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Fig. 3: Experimental Setup for Pyrolysis
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3.1 Experimental Procedure
1) Sweep gas (N2) is fed into the reactor into two parts. First part i.e. 50% of total feed gas is
preheated at reactor temperature and second enters reactor at room temperature form
the top with the feed. A furnace was used to supply initial heat needed for the pyrolysis.
2) The auger screw feeder was used to continuously feed the microalgae into the bed at
prescribed flow rate once the reactor reaches a required temperature.
3) All the connection between reactor and condensing system is maintained at 400 oC so as
to avoid any condensation in the pipe line. Product vapours were condensed and collected
for analysis in a condensing system that contained three condensers located in an ice bath
(0 oC), followed by a condenser operated with liquid N2 (-196 oC).
4) The pyrolytic oil from the condenser will be analyzed using a gas chromatograph
equipped with a mass selective. The GCMS conditions were as follow: ionization mode
electron impact (70 eV); MS operated in the total ion current mode, scanning from 40 to
550 m/z; interface temperature of 240 oC.
5) The GC oven temperature program for the bio-oil samples was carried out at an initial
temperature of 40 oC, which was held for 1 min, followed by a ramp at 20 oC / min to 320
oC where it was held for 20 min.
6) The injector temperature was 270 oC and the helium carrier gas was kept constant (1
ml/min. The bio-oil samples (0.1 g) were diluted in dichloromethane (1 ml); and 1 l was
injected to the GC.
7) A mass spectral library data from the National Institute of Standards and Technology
(NIST) was used for the identification of the compounds found in sample.
8) The uncondensed vapor would be collected in the gas bags and would be analyzed for
different hydrocarbon, H2, and other gases using gas spectrophotometer.
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3.2 Selection of Catalyst
CATALYST BIO OIL YIELD
H-ZSM5 19.7
K2Cr2O7 35.5
KAc 37.5
Al2O3 39
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Fig. 4(a) Fig. 4(b)
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Fig. 4(c) Fig. 4(d)
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Fig 5: Pyrolysis Reactor
CHAR
PYROLYTIC FLUID
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3.3 Catalyst Preparation Protocol
1) The catalyst was prepared through ion-exchange.
2) The protonated and sodium -ZSM-5 were prepared following the procedure employed by
Metkar et al. H-ZSM5 was prepared by calcinating NH4ZSM-5 at 500 C for 5hrs.
3) The Ni-ZSM-5 was prepared by a series of ion exchange and washing steps starting with
the ammonium form and ending with the Nickel form; i.e., NH4+ H+ Na+ Ni+2.
Zeolite powder in the ammonium form (NH4-ZSM-5 MFI type) was provided by Sud-
Chemie (Delhi,India) having a Si/Al ratio of 25.
4) The NH4-ZSM-5 was then converted into the protonated form by calcining the powder at
500oC for 5 hours.
5) Exchange of H+ with Na+ involved contacting the H-ZSM-5 with a 0.1 M NaNO3 solution.
The solution contained a concentration of Na+ that was about two times the number of
Al3+ ions. This exchange was carried out for 3 hours in a continuously stirred solution at
ambient temperature and a pH of 7-7.1.
6) NH4OH or acetic acid was used to adjust the pH of the solution. After the ion exchange was
completed the particles were filtered and dried at 110oC for about 2 hours.
7) After ion- exchange, the salt is washed with de ionized water twice to remove any
unwanted particle in the salt.
8) In the final step Na-ZSM-5 was converted to Ni-ZSM-5 by performing ion-exchange in a
solution containing nickel (II) nitrate Ni(NO3)2 of .
9) Different conditions (e.g. concentration of Ni(NO3)2 , temperature, pH, and contact time)
were employed to determine the procedure for content of nickel in the zeolite.
10)Approximately Thirty grams of Na-ZSM5 were ion-exchanged with a Ni(NO3)2.
11)After the ion exchange the sample is dried and washed.
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Figure 6: Protocol for preparation of Catalyst, Ni-ZSM5
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3.4 Thermogravimetric Analysis
The study of the behaviour of biomass and its component plays a crucial role in modelling the
kinetics and reactor of a biomass pyrolysis. The kinetics of biomass pyrolysis is important in
context of thermo-chemical conversion process aimed at production of fuel gases, bio-oil or char.
In our work we would be studying the pyrolysis kinetics of one of the most abundant and widely
grown algae chlorella vulagaris. Algae are a complex material composed of lipids, carbohydrates
and proteins. Lipid is the component of algae which decides the overall yield and property of the
bio-oil from algae. While the other constituent like carbohydrate and protein plays an important
role in stability of the bio-oil formed as they are the main source of oxygenates and nitrogenates
formed during pyrolysis. Therefore, the study of the decomposition behaviour of each of the
component along with the biomass will play crucial role in optimizing the pyrolysis setup.
Another most prominent mechanism which is industrially employed to convert biomass into fuel
is through Combustion. So here we have done a comparative study between pyrolysis and
combustion by performing our thermogravimetry analysis in two different atmospheres, N2 and
Air. Kinetic study for both the process were performed and compared in the study. The specific
aim of the thermogravimetric analysis in our study is as follows:
1) To study the decomposition behaviour under different heating rates and atmospheres.
2) To compare pyrolytic and oxidizing behaviour of algae biomass.
3) To model the kinetics of pyrolysis and combustion of bio-mass and its components.
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3.5 Materials required for experiment
Sample of chlorella vulgaris from Altret Bio-fuel. The sample was dried at 100 C for 24 hr.
This table shows the theoretical composition of chlorella vulgaris from the literature.
COMPONENT PERCENTAGE
Protein 51-58
Carbohydrate 12-17
Lipids 14-20
3.6 Method of Experiment
Thermogravimetric Analysis was carried out on Perkin Elmer Pyris Diamond TG-DTA.
Baselines were corrected by subtraction of predetermined baselines determined under indentical
condition except for absence of a sample. Small sample were loaded into an alumina crucible for
each run under non-isothermal conditions. Before the analysis sample was kept at 100 C for 24
hrs to remove all the free moisture present in the sample. Then the sample was heated ate the
heating rate of 5,10,20,30,40 C/min from 50 C up to 800 C in the atmosphere of Air or N2 to study
the pyrolytic and combustion behavior. All the experiments were repeated thrice to validate the
results.
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Chapter 4: Algal Pyrolysis Reactor Modeling
Besides experimental research, numerical simulation is another important tool for reactor design
and experimental data interpretation. To have a complete understanding of the system, a model
was developed in our work to simulate biomass pyrolysis behavior in Moving Bed Reactor. For
the modeling of the moving bed reactor, reactor was divided into 4 different zone based upon the
reaction taking place in each zone.
Fig 7: Zones for modeling of reactor
Heterogeneous Reactor
Two Phase Catalytic Reactor
Homogeneous Reactor
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4.1 Description of each Zone
Heterogeneous Reactor (Zone 1): In this zone primary reaction which is taking place is the
decomposition of algal bio-mass into vapour and char. The composition of vapour phase in very
complex and majorly consist of aromatic, non aromatic, oxygenates, nitrogenates, aromatic
oxygenates and aromatic nitrogenates. The reaction kinetics in this zone would be modelled by
the rate of degradation equation which was obtained from TGA. Due to the continuous generation
of vapour there is an increase in vapour velocity. In this zone, little amount of secondary
decomposition of vapour will also take place which is neglected in our case.
Heterogeneous Reactor (zone 2):In this zone the reaction taking place is same as that of zone
1. But the major difference in the two zone is that there is a continue deposition of solid in zone 2
and the solid phase is static in this case. The continuous decomposition of solid in this zone is
taken care by assuming that due to the deposition of solid there is change in solid fraction within
a given length of the reactor.
Two Phase catalytic reactor (zone 3): In this zone the catalytic upgradation of the vapour
would be taking place. The reaction which would take place in this zone are mainly conversion of
oxygenates into hydrocarbon and water and nitrogenates into hydrocarbon and ammonia.
Homogenous Reactor (zone 4):In this zone the secondary decomposition of vapour would take
place. Higher molecular weight hydrocarbon would break down into the lower molecular weight
hydrocarbon.
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4.2 Modeling Equations
The detailed 2-dimensional model describes that the concentration C(r,z, t) and temperature T(r,
z ,t) as a function of the radial, axial coordinates and time is given by the following equations.
MASS BALANCE
where:
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HEAT BALANCE
where:
But taking reasonable approximation depending upon our system could simplify the above
equation to a great extent. We would model each zone separately with different set of
assumptions in each case. As explained above both in Zone 1 and 2, basic reaction taking place is
same. In both the zone pyrolysis of solid particle is taking place to give us char and gas as our
product. So if we model a individual particle of a biomass separately, its model would remain
same in both the zone. The difference would come in the manner how we integrate the
simultaneous reaction taking place on different particle in space and time. Let us start with
modeling single solid particle and would later in the chapter deal with the specifics of Zone 1 & 2.
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4.3 Steady State Modeling Two-phase Catalytic reactor (Zone 3)
Governing Equations assuming 1stOrder Kinetics
(
)
(
)
where:
Cmis the Dimensionless mixing Cup concentration
Csis the Dimensionless surface concentration
is the Dimensionless mixing cup temperatureis the Dimensionless surface temperature
Z is the Dimensionless axial time
Da1= Local mass Damkohler Number
Da2= Local heat Damkohler Number
B = Adiabatic temperature rise
= Dimensionless activation energy
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Boundary Conditions
Cm =1 @ Z=0.6(a) & k3 = Da1.6(b)
Constants Defined
k1 = Da / Da1 & k3 = Da1
k2 = Da / Da2 & k4 = B*Da2
Assumingtending to infinity the equations reduce to
( )
(
)
Differentiating Equation (9) w.r.t. Z
(
)
Equating equations (12) & (7) we get:
Similarly by Differentiating Equation (10) w.r.t. Z and following same procedure we get:
(
)
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Chapter 5: Simulations (Steady State)
Fig. 8(a) CmVs Z
In this plot we find that the mixing cup concentration at steady state for Zone 3 of a reactor
decreases exponentially with Z (as we move outwards towards the surface) .
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Fig. 8(b) CsVs Z
In this plot we find that the suraface concentration at steady state for Zone 3 of a reactor
increases exponentially with Z (as we move outwards towards the surface) .
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Fig. 8(c) m Vs ZIn this plot we find that the mixing cup temperature at steady state for Zone 3 of a reactor
decreases exponentially with Z (as we move outwards towards the surface) .
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Fig. 8(d) s Vs ZIn this plot we find that the surface temperature at steady state for Zone 3 of a reactor decreases
exponentially with Z (as we move outwards towards the surface) .
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Chapter 6: Unsteady State Modeling
Unlike the first two zones where the reaction term is coming in the conservation equation, in this zone
the reaction term would appear in the boundary condition. Equations given below in dimensionless
form is given below generally describe such system.
(
) (
)
(
) (
)
Where:
C = CL2 at y = yL2 at
Boundary Conditions
at at
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(
)
( )
where:
In the two phase model we eliminates the transverse co-ordinate by using the concept of an e!ective
transfer coeffcient between the bulk and the surface. Specifically, the local mass transfer coefficient or
Sherwood number which is defined by:
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and the heat transfer coeffcient expressed using Nusselt number as:
When constant values are used for the Sherwood and Nusselt numbers, the one-dimensional two-
phase model is described by the differential-algebraic system and where cm(ym) is the mixing cup
concentration(temperature). When constant values are used for the Sherwood and Nusselt numbers,
the one-dimensional two-phase model is described by the differential-algebraic system.
( )
( )
Where,
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Chapter 7: Simulations (Unsteady State)
Fig. 9(a) Cmvs Time
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Fig. 9(b)Cmvs Z
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Fig. 9(c)Cmvs Time
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Fig. 9(d) Csvs Z
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Fig. 9(e)
mvs Time
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Fig. 9(f)
mvs Z
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Fig. 9(g) svs Time
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Fig. 9(h)
svs Z
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Chapter 8: Conclusion
8.1 Summary
1) From thermogravimetric analysis we were able to study the pyrolysis behavior of
the biomass at different heating rates.
2) A pyrolytic reactor has been designed to extract the bio-oil from biomass via
pyrolysis.
3) For the modeling of pyrolysis reactor, it was divided into 4 sub zones depending
upon type of reaction taking place.
4) Modeling equations were formulated for zone 3.
5) The Variation of Surface concentration, Mixing Cup concentration, Surface
Temperature & Mixing cup Temperature are given as follows:
I. Mixing Cup concentration increases with time
II. Mixing Cup concentration decreases as we move outwards towards the surface
III. Surface concentration increases with time
IV. Surface concentration decreases as we move outwards
V. Mixing cup Temperature increases with time
VI. Mixing cup Temperature decreases initially as we move outwards towards the
surface but then gradually starts to increase after attaining minima.
VII. Surface Temperature initially increases exponentially with time but later starts
decreasing in a parabolic fashion after attaining maxima.
VIII. Surface Temperature remains almost constant.
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8.2 Future Work
1) Thermogravimetric analysis and kinetic modeling of each of the component of bio-
mass i.e. lipid, protein and carbohydrate
2) Performing the pyrolysis experiment for different catalysis and compare the
upgradation of oil in each case.
3) Preparation of different catalyst which could lead to a better quality of oil.
4) Study of pyrolysis of model compounds of carbohydrate, protein and lipids to better
understand the chemistry behind the pyrolysis of bio-mass.
5) In the future catalyzed and non-catalyzed pyrolysis of the biomass will be
performed to have a understanding of the biomass and its pyrolysis characteristics.
6) Study of individual component will also allow us to decide the criterion for the
selection of catalyst for the upgradation purposes
7) The final aim of this study is to have a detailed understanding of the pyrolysis
system of the microalgae Chlorella vulgaris through modeling and experimentation.
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Appendix
clc;
clear all;
close all;
%Parameters Defining (They need to be assigned values)---------------------
Da = 1 ;
Dapm = 0.1 ;
Daph = 0.3 ;
gam = 1 ;
R = 1 ;
clea = 31
k1= Dapm*R ;
k2= Daph*R ;
k4= Da/Dapm ;
k5= Da/Daph ;
L = 1;
T = 1;
p = 21;
n = 101;
xp1 = L/(p-1)
xt1 = T/(n-1)
delx= 1 ;
delt= 1 ;
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C0 = 1;
T0 = 0.5;
%-------------------------------------------------------------------------- %Need to assign c0 and t0 ; these are initial values
%-------------------------------------------------------------------------
fori = 1:delx:p
cm(i,1) = C0 - ((0.1)*(C0)*((i-1)/(p-1)));
tam(i,1) = T0 - ((0.1)*(T0)*((i-1)/(p-1)));
end
%-----------------------------------------------------------------------
%calculating tas,cs initially at t = 0
%calculated using succesive iteration
%--------------------------------------------------------------------------
forp1 = 1:delx:p
start=1;
i=-1;
diff1=0;
diff2=0;
while(start)
i = i + 0.01;
i1 = i;
i2 = i1 + 0.01;
diff1 = (i1-tam(p1,1)) + k2*(cm(p1,1))*exp(i1/(1+(i1/gam)))/(1 +
(k1*exp(i1/(1+(i1/gam)))));
diff2 = (i2-tam(p1,1)) + k2*(cm(p1,1))*exp(i2/(1+(i2/gam)))/(1 +
(k1*exp(i2/(1+(i2/gam)))));
if((diff1*diff2)
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tas(p1,1)=i2;
cs(p1,1)= cm(p1,1)/(1 + (k1*exp(i2/(1+(i2/gam)))));
endtas
clea
%--------------------------------------------------------------------------
%Discretization of the diiferential equation...
%The scheme used is forward space and forward time.....................
%--------------------------------------------------------------------------
fort1 = 1:delt:(n-delt)
t2 = t1+delt;
cm(1,t2) = cm(1,t1) + (cm(1,t1)-cm(2,t1))*(delt*xt1)/(delx*xp1) +
k4*(delt*xt1)*(cm(1,t1)-cs(1,t1))
tam(1,t2) = tam(1,t1) + (tam(1,t1)-tam(2,t1))*(delt*xt1)/(delx*xp1) +
k5*(delt*xt1)*(tam(1,1)-tas(1,t1));
forp1 = 2:delx:p-1
cm(p1,t2) = cm(p1,t1) + (cm(p1-1,t1)- cm(p1+1,t1))*(0.5*delt*xt1)/(delx*xp1) +
k4*(delt*xt1)*(cm(p1,t1)-cs(p1,t1));
tam(p1,t2) = tam(p1,t1) + (tam(p1-1,t1)- tam(p1+1,t1))*(0.5*delt*xt1)/(delx*xp1)
+ k5*(delt*xt1)*(tam(p1,1)-tas(p1,t1));
end
cm(p,t2)= cm(p,t1) + (cm(p-1,t1)-cm(p,t1))*(delt*xt1)/(delx*xp1) + k4*(delt*xt1)*(cm(p,t1)-
cs(p,t1));
tam(p,t2) = tam(p,t1) + (tam(p-1,t1)-tam(p,t1))*(delt*xt1)/(delx*xp1) +
k5*(delt*xt1)*(tam(p,t1)-tas(p,t1));
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start=1;
i=-1;
diff1=0;
diff2=0;
forp1 = 1:delx:p
while(start)
i = i + 0.01;
i1 = i;
i2 = i1 + 0.01;
diff1 = (i1-tam(p1,t2)) + k2*(cm(p1,t2))*exp(i1/(1+(i1/gam)))/(1 +
(k1*exp(i1/(1+(i1/gam)))));
diff2 = (i2-tam(p1,t2)) + k2*(cm(p1,t2))*exp(i2/(1+(i2/gam)))/(1 +
(k1*exp(i2/(1+(i2/gam)))));
if((diff1*diff2)
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fort1 = 1:delt:n
ha = t1;
x1 = 0:delx:p-1 ;
plot(x1,cm(x1+1,ha))hold on
end
end%check
if(0)
forx1 = 1:delx:p
ha = x1;
t1 = 0:delt:n-1 ;
plot(t1,cm(ha,t1+1))
hold on
end
end%check
%-----------------------------Tam---------------------------------------
if(0)
fort1 = 1:delt:n
ha = t1;
x1 = 0:delx:p-1 ;
plot(x1,tam(x1+1,ha))
hold on
end
end%check
if(0)
forx1 = 1:delx:p
ha = x1;
t1 = 0:delt:n-1 ;
plot(t1,tam(ha,t1+1))
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hold on
end
end%check
%------------------------------Cs-----------------------------------
if(0)
fort1 = 1:delt:n
ha = t1;
x1 = 0:delx:p-1 ;
plot(x1,cs(x1+1,ha))
hold on
end
end%check
if(0)
forx1 = 1:delx:p
ha = x1;
t1 = 0:delt:n-1 ;
plot(t1,cs(ha,t1+1))
hold on
end
end%check
%--------------------Tas-----------------------------------------------
if(0)
fort1 = 1:delt:n
ha = t1;
x1 = 0:delx:p-1 ;
plot(x1,tas(x1+1,ha))
hold on
end
end%check
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%if(0)
forx1 = 1:delx:p
ha = x1;t1 = 0:delt:n-1 ;
plot(t1,tas(ha,t1+1))
hold on
end
%end
%---------------------------------------------------------------------
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References
[1] W Peng ,Q Wu ,P Tu. Effect of temperature and holding timeon production of renewable fuels
from pyrolysis of Chlorella protothecoides. J Appl Phycol 2000;12:147 52.
[2] AV Bridgwater . Principles and practice of biomass fast pyrolysis processes for liquids. J Anal
Appl Pyrol 1999;51:3e22.
[3] SRA Kersten, WP van Swaaij ,L Lefferts ,K Seshan. Options for Catalysis in the thermochemical
conversion of biomass into fuels. Willey-VCH; 2007. p. 119e62.
[4] PL Desbene ,M Essageph ,B Desmazieres ,F Applied Catalysis B: Environmental, Villeneuve
.Analysis of biomass pyrolysis oils by combination of various liquid chromatography techniques
and gas chromatography-mass Spectroscopy. Journal of Chromatography 1991;53:2112
[5] Ye N, Li D, Chen L, Zhang X, Xu D (2010) Comparative Studies of the Pyrolytic and Kinetic
Characteristics of Maize Straw and the Seaweed Ulva pertusa. PLoS ONE 5(9): e12641.
doi:10.1371/journal.pone.0012641
[6]Meir D.New Methods for chemical and physical characterization and round robin testing.In:
Bridgwater A, et al., editors.Fast pyrolysis of biomass: a handbook.Newbury, UK: CPL Press; 1999.
p.92101. [35]Scholze B, Hanser C, Meier D.
[7] Q Lu , X F Zhu, W Z Li, et al. On-line catalytic upgrading of biomass fast pyrolysis products.
Chinese Sci Bull, 2009, 54: 1941-1948.
[8] Beatriz Valle, Ana G. Gayubo, Andr_es T. Aguayo, Martin Olazar, and Javier Bilbao Selective
Production of Aromatics by Crude Bio-oil Valorization with a Nickel-Modified HZSM-5 Zeolite
Catalyst Energy Fuels 2010, 24, 20602070.
[9]A kinetic study of pyrolysis and combustion of microalgae Chlorella vulgaris using thermo-
gravimetric analysis by Ankit Agrawal, Saikat Chakraborty, Department of Chemical Engineering,
Indian Institute of Technology, Kharagpur.