energy scenario for transportation - iit kanpur 1-4.pdf · primarily liquid fuels. ... nitrogen...
TRANSCRIPT
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Energy Scenario for Transportation in Future
Avinash Kumar Agarwal Professor
Department of Mechanical Engineering
Indian Institute of Technology, Kanpur, India
2050, world population: 8‐10 billion
80% people: urban areas
Average income: US $ 15‐25,000 per annum
Per capita energy demand(2050):
2‐3 times that of present
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Introduction Challenge for us in India is to follow a flat trajectory of growth in fuel demand
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Production and import of crude oil in India
82 MMt of crude oil (70% of our requirement) and petroleum products in 2003‐2004
causing a heavy burden on forex reserves.
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The known worldwide reserves of petroleum are 100 billion barrels and these are predicted to last about 40 years, hence the availability of petroleum is uncertain in future.
Alternative fuels have to be considered in order to undertake energy security and import substitution for diesel and petrol fuels.
No single fuel can sustain urban transport in the foreseeable future.
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The Contributors Demography Incomes Urbanization liberalization
The Critical Resource constraints technology Social and personal priorities
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World oil production will peak but when? 10‐30 years
What is more important is “When will demand exceed supply?” ‐ < 10 years according to pessimists
Demand in 2004 ~ 82 M barrels a day, expected to rise to 84 M barrels a day in 2006 (source IEA) – pessimists say supply will not keep up, optimists say it will
Are oil prices high now because of cyclical or structural reasons? Difficult to answer
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World Oil Demand and Supply Trends
More natural gas available. More “unconventional” oil e.g. tar sands, shale ..
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World Environment Day 2006, June 10th, Institution of Engineer, Kanpur
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Technology and human ingenuity will ensure that future energy demands will be met fairly, cleanly and peacefully
Energy conservation
Development of renewable and biomass
Unconventional fossil fuels – heavy oil, tar sands (Alberta project), shale, coal bed methane
New oil production techniques
More oil fields
Development of coal technology
CO2 sequestration
Nuclear energy 9
How will the world manage energy in the future? – An optimistic view
Primarily liquid fuels.
Primarily made from crude oil in refineries.
Why liquid fuels ?
High energy density – Gasoline ~ 32 MJ/ litre, Diesel ~36 MJ/ litre
Easy transport, storage and handling Extensive distribution network
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Transport Fuels
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The 21st Century ‐ Further Growth projected in Motorization
Billions of light duty vehicles
12 Source: IEA, OXF, SH
Gasoline*
New
Car S
ales
There is no single solution for future fuels
CNG/LPG Diesel/HCCI Diesel HEV Gasoline HEV Gasoline/HCCI FCV
Diesel
The next 20-30 years will see a wider range of vehicle technologies and
fuel types especially in developed markets.
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Hydro
Geothermal
Solar PV
Solar Thermal
Wind
Hydrogen
Biomass and Biogas
Alcohols
Biodiesel
CNG, LPG
Renewable Energy Resources
Reduction in underground based carbon energy sources
Serious modifications in earth’s surface layer
Subsidence of surface ground after extraction of minerals
Increase in CO2 levels in atmosphere from 280 PPM in pre‐industrial era to
350 PPM now
CO2 levels are still climbing as a function of fuel burnt
Green house effect
Acid rains, smog and change of climate
Environmental Implications of Using Fossil Fuels
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Modifications in the existing engine hardware
Investment costs for developing infrastructure for
processing alternative fuels
Environmental compatibility compared to conventional
fuels
Additional cost to the user in terms of routine
maintenance, engine wear and lubricating oil life
Alternative Fuel Factors
Regulated Compounds
o NOx, CO, HC, Particulate Matter (PM)
Unregulated Compounds
o Formaldehyde
o Benzene, Toluene, Xylene (BTX)
o Aldehydes
o SO2
o CO2
o Methane
Regulated and Unregulated Pollutants
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Contribution to Different effects
Short‐term health effects
Carbon monoxide
Nitrogen Oxides
Particulate Matter
Formaldehyde
Long‐term health effects
Poly‐aromatic
hydrocarbons
Benzene, Toluene, Xylene
Formaldehyde
Contribution to Different effects
Regional Effects
Summer Smog
Aldehydes
Carbon Monoxides
Nitrogen Oxides
Winter Smog
Particulate Matter
Acidification
Nitrogen Oxides
Sulphuric Oxides
Global Effects
Carbon Dioxide
Carbon monoxide
Methane
Non‐Methane
Hydrocarbons
Nitrogen Oxides
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Carbon Monoxide
Fatal in large dosage, Aggravate heart disorders, effect central
nervous system, Impairs oxygen carrying capacity of blood
Nitrogen Oxides
Irritation in respiratory tract
Hydrocarbons
Drowsiness, Eye irritation, Coughing
Health Effects of Vehicular Pollution
Ill Effects ‐ 80 ‐ 90% of lead in ambient air is attributed to
combustion of leaded petrol. Since children inhale a
proportionately higher volume of air than adults their
lung deposit rate is about 2.7 times higher than that of
adults. Infants and children below five are particularly
sensitive to lead exposure because of it’s potential
effect on neurological development.
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The price we pay ‐ The health cost of ambient air pollution
in Delhi alone is US$ 100 ‐ 400 million per year. For a
country as a whole, it may run into billions of dollars.
Major Culprit ‐ Automobile manufacturers argue that thirty
million odd poorly maintained vehicles plying on the roads
negate all their efforts to clean up the air through
improved efficiency of new vehicles because no inspection
and maintenance system for older vehicles is enforced in
India.
Several alternative fuels have been used either on an
experimental basis or occasionally on a commercially
viable basis, in various parts of the world, for a long time
motivated by availability of a local resource which became
economically viable because of rising prices of petroleum
products particularly since the OPEC oil embargo of the
70’s and occasionally by some environmental regulations.
Alternative Fuels : An Overview
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Not only will it adversely affect India’s energy security,
but it will also mean a significant drainage of precious
foreign exchange reserve.
India’s dependence on imported oil is close to 50%.
Without addition to the domestic reserve of crude oil
and no switch to alternative energy, India’s
dependence on imported oil may go up to 90% within a
few years.
India has moved to become road‐dependent economy in
the nineties from traditionally railroad dependent
economy.
A 1995 World Bank study shows that per capita travel per
year in India is 2300 km much more than other countries
relative to their respective income levels.
With this growth of automobile sector, particularly of the
two wheeler segment accounting for about of 80% of the
total number of vehicles, the impact on environment is
likely to be significant.
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India has an abundant stock of coal reserve enough to meet
India’s requirements for more than 200 years.
Environmental friendly technologies are available to produce
power or methanol from coal.
Industry observers believe India’s resource balance may come
out strongly in favour of alternative fuel driven vehicles.
Local and global environmental concerns, availability, local issues….
Enable or adapt to new engine technology – e.g. low sulphur fuels, fuels for HCCI engines?
Renewable Biofuels
Cleaner Hydrocarbon Fuels such as GTL diesel (coupled with improvements in internal combustion engines). LPG, CNG, Dimethyl Ether (DME)
Changes should be sustainable ‐ fulfil primary requirements while reducing local and global environmental impact and Should be acceptable to consumers
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Why should fuels change?
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Will constitute a great majority and will need to change to fit with changes in engine technology
Examples
Sulphur levels will continue to come down in both gasoline and diesel fuels. The pace of this change should be driven by the pace at which new engine technology requiring such fuels is introduced but will be affected by legislative initiatives.
Gasoline specifications will need to change
Direct Injection Spark Ignition (DISI) engines might work better with higher volatility fuels.
“Unconventional Fuels” – Biodiesel, Bio‐Fuels, Gas‐to‐liquid (GTL) fuels, LPG, CNG, LNG, Hydrogen
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Conventional Fuels
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Gas to Liquid (GTL) Fuels
Make sense in the current environment if there is “stranded” gas. But there might be other scenarios in the future.
Could also be made from biogas but significant challenges.
Extremely high quality diesel product – 75‐80 Cetane, zero sulphur and aromatics, odourless, colourless, non‐toxic, biodegradable
Emissions benefit, for pure and blended product, well established for existing engine technology.
Sustainability – clear benefits over conventional diesel in NOx and SO2, neutral on CO2.
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34,000 68,000
140,000
130,000
150,000
160,000
34,000
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
These projects have the capacity to produce ~15 million tonnes of GTL Gasoil annually (about 4-5% of world road diesel demand by 2015)
bb
l/d
ay
ConocoPhillips
ExxonMobil
Sasol - Chevron
Shell Qatar
Sasol Qatar - Oryx 1+
Sasol Nigeria
Sasol Qatar - Oryx 1
Shell Bintulu
Potential Global GTL Capacity by 2015
Alcohol fuels, methanol and ethanol have similar physical properties and
emission characteristics
Produced from Coal, Natural Gas, Crude Oil, Biomass or even organic waste
Methanol CH3OH is a simple compound
Contains no sulphur or complex organic compounds
Organic emissions (Ozone precursors) will have lower reactivity than
gasoline hence lower Ozone forming potential
If pure methanol is used then minimal emission of benzene, and PAHs
Higher engine efficiency
Less flammable than gasoline
Methanol
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But
Range as much as half less, so larger fuel tank
M100 has invisible flames
Explosive in enclosed tanks
Cost somewhat higher than Gasoline
Toxic, Corrosive characteristics, Ozone Creative formaldehyde
emissions
Environmental hazard in case of spill, as it is totally miscible with
water.
Methanol
Similar to Methanol, but considerably cleaner, less toxic and less corrosive
Greater engine efficiency
Grain alcohol, and can be produced from agricultural crops e.g. sugar
cane, corn etc.
But
More expensive to produce
Lower range, Cold starting problems
Require large harvest of these crops
More energy input required in production
Leads to environmental degradation problems such as soil degradation
Ethanol
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Natural Gas can be used as CNG or LNG. Primarily CH4
LNG is rarely used since it is expensive and more difficult to handle than CNG
CNG is relatively well‐tested fuel. Abundant Supply
Technology for substituting CNG is gasoline and diesel engine is more than 55 years old
Millions of Vehicles use CNG as fuel. Safer fuel as it ignites at higher temp than diesel and
gasoline
Easy conversion of Gasoline cars to CNG. Much lower operating cost
Lesser CO emissions than Gasoline or Methanol as CNG mixes better with air than liquid fuels
Require less enrichment for engine start‐up
Essentially no unregulated pollutants (like Benzene), Smoke, SOx, and slightly less formaldehyde
than gasoline vehicles
Lower ozone forming potential
CNG
But
Extent of reduction of pollutants will depend on the emission control system.
Emits similar or possibly higher NOx than Gasoline or Methanol vehicles
Low range per filling
Slower pick‐up
10‐15% Power loss
Longer re‐fuelling time
Infrastructure for distribution needs
Moderate performance of dual fuel “Transition” vehicles
CNG
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LPG mainly contains propane and Butane
By‐product of extraction and refining of crude oil and Natural Gas
processing
10‐15% quantity of Petroleum produced
3% of the quantity of Natural Gas
But
Availability closely linked to crude oil production and refining therefore
supply limitations
Important Kitchen Fuel
Lower HC, Higher NOx, Lower Pickup, Lower Power, Low Range.
LPG
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LPG, LNG, CNG, DME
Gases at normal temperature – require new infrastructure for
transport and storage
Significantly cleaner than conventional diesel for NOx,
particulates. Lower CO2.
Reduction in power?
Potential as niche fuels, especially where urban air quality is
problematic.
(LPG quality better controlled and less bulky storage compared
to LNG)
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Attractive, Clean Combustion, except NOx
Virtually non‐polluting. Big greenhouse advantage
Water as combustion product
Domestically produced from water by electrolysis
Significantly reduces transport related Ozone and CO
Advanced lean burn hydrogen engines produce nominal amount of NOx.
Hydrogen, if used in fuel‐cell, doesn’t produce NOx.
But
Technology has not matured.
Limited Range, need heavy & bulky storage
Hydrogen is expensive as yet.
Availability? Infrastructure?
Hydrogen
Not an energy source but an energy carrier. Production is energy
intensive.
Production from natural gas or coal , produces CO2
Electrolysis of water using electricity from renewable (at the moment
< 0.5% of total energy use) or nuclear (waste disposal, proliferation
issues).
Why convert electricity to H2?
Much greater reduction in CO2 if renewable energy is used to replace
coal‐generated electricity.
Hydrogen production must use CO2‐free primary energy
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Hydrogen as a Transport Fuel ‐ Production
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Volumetric energy content ~ 3200 times lower than liquid fuels at room
temperature/pressure ‐
Compression (~ 25% energy lost)
Liquefaction (~40% of energy lost).
Storage in hydrides and carbon nanotubes not fully developed,
currently not very efficient – exothermic (upto 30% energy loss) .
Extensive infrastructure investment needed for distribution. Costs
~15x of liquid hydrocarbons, 4x natural gas (IEA). Liquid H2 transport
too risky.
Significant safety issues 39
Hydrogen ‐ Transport and Storage
Renewable fuels from bio‐resources
Include
Ethanol
Biodiesel
Bio‐hydrogen
Biogases
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What are Biofuels ?
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POLLUTION THREAT
REDUCTION OF GREEN HOUSE GAS EMISSIONS
REGIONAL (RURAL) DEVELOPMENT
SOCIAL STRUCTURE & AGRICULTURE
OF SUPPLY
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WHY BIOFUELS?
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Bio-Fuels (made from plant material) Sugar, starch, vegetable oils, residues to ethanol, bio‐esters, diesel ….
Import substitution/self reliance/security of supply
Use for agricultural surpluses/rural employment
Bio‐waste management
Greenhouse gas credit – “Sun” fuels
Current costs are 2‐4 times conventional fuels
Availability will be limited ~5‐6% of total transport needs because of
competition for land use with food crops (source iea.org)
Energy efficiency of production will improve (Cellulosic feedstocks, GM/energy
crops)
Ethanol – 275 litres/ tonne of dry plant material. FutureEE
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Liquid fuels from renewable sources
Don’t over‐burden the environment with emissions
Potential for making marginal lands productive
Lesser energy input in production
Higher energy content than other energy crops
Cleaner emission spectra
Simpler processing technology
But
Not economically feasible yet
Need further R & D work for development of On‐Farm processing technology
Vegetable oils
Vegetable oils can be successfully used in C I Engines by
Engine Modifications
Dual Fuelling
Injection System
Modification
Heated Fuel Lines
Fuel Modifications
Blending
Transesterification
Cracking/ Pyrolysis
Hydrogenation to Reduce
Polymerization
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Biodiesel is receiving increasing attention in India
India has large size of the rural economy, energy self‐sufficiency and
environmental concerns.
Diesel consumption in India is about five times higher than gasoline.
The cost of diesel fuel is high due to high crude oil price and processing cost for
desulphurisation (This is essential for meeting Bharat norms).
Biodiesel is being looked into as partial substitute for these mineral based diesel
fuels.
Biodiesel offers the advantage of rural employment generation and utilization of
degraded land, marginal land and wasteland, thus strengthening the rural
economy.
India has approximately 100 million hectares of degraded land, which can be
utilized for biodiesel crops. 45
Biodiesel for India
Biodiesel has higher flash point temperature, higher cetane number, lower sulfur
content, lower aromatics and higher oxygen content than mineral based diesel.
It is well‐established fact that biodiesel fuelled engines emits significantly lower
regulated emissions compared to diesel.
The non‐regulated emissions like poly aromatic hydrocarbons, nitrated poly
aromatic hydrocarbons and sulfate emissions etc. are also lower for biodiesel.
Biodiesel is a carbon neutral fuel and its carbon cycle time is very low compared
to mineral diesel.
Indian biodiesel program is based on non‐edible oils.
These non‐edible oils may be rice‐bran, sal, neem, mahua, karanja, castor,
linseed, jatropha, honge, rubber seed etc. Most of these tree/ crop based oils
grow well on wasteland and can tolerate long periods of drought and dry
conditions. 46
Biodiesel for India
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EV is zero emission from the vehicle, consequently Promises urban air‐quality
Fuel widely available, Greenhouse advantage
Full effect of EV use on total emission will be country specific, depending
largely on fuel‐mix used for power generation
But
Low Range per charge, Low power
Low speed
Long charging time
Non‐availability of long life, lighter batteries
Disposal of Old batteries is environmental hazard
Electric Vehicles
India has been one of the pioneering countries to start
exploring the commercialization aspects of Electric
Vehicles (EV).
The first EV prototype was manufactured in 1980.
The Ministry of Nonconventional Energy Sources (MNES),
Government of India had sponsored a project under which,
during 1981 to 1984 Bharat Heavy Electricals Limited
(BHEL) designed and manufactured ten prototypes of an
eighteen‐seater electric vehicle.
REVA Car is a success story
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Major customer of BHEL for their electric buses has been
the Delhi Energy Development Agency (DEDA) who have
been running BHEL electric mini buses in several parts of
Delhi since 1987.
According DEDA, the buses are not commercially viable
under ordinary circumstances.
Cost per passenger km for these buses comes to about
double the cost for conventional diesel buses.
The payload is only 25% as opposed to about 60% for diesel
buses.
The five specific factors that make EV naturally appropriate for
India in the long run, and CNG vehicle in the foreseeable future
are:‐
the environmental situation in India,
the transportation needs and driving habits of the people,
the features of the currently available EV/CNG technology,
the climatic advantage, and
the resource balance of the country under different technology
options
Viable Option For India
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Method of increasing range of EV
Have both, an I C Engine and an electric motor
Electric motor operates, when the vehicle needs extra power
Hybrid Vehicle combines the good qualities of electric car as
well as I C Engine
But
Higher Cost
Integration of two technologies often ends up in a mess
Hybrid Vehicles
Fuel Properties
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Fuels: Performance Properties (1) Calorific Value
Solids and Liquids ‐Defined as the heat liberated in kJ by complete combustion of 1 kg of fuel.
For Gases – Expressed in kJ/m3 of gas at S.T.P.
Further classified as higher calorific value (HCV) and lower calorific value (LCV):
(a) Higher Calorific Value (HCV)
All fuels containing hydrogen in the available form will react with oxygen during combustion to
generate steam.
The steam may condense when the products of combustion are cooled to initial temperature.
This results is maximum heat being extracted. This heat value is called Higher or Gross Calorific Value
(HCV)
(b) Lower Calorific Value (LCV)
It is the difference in the HCV and the heat absorbed by water during its conversion to vapor,
constituents supplied at air temperature.
The amount of latent heat depends on the pressure at which the phase change has occurred, which
is difficult to estimate.
It may be assumed for the evaporation to take place at saturation pressure corresponding to Std.
temperature of 15 °C.
The latent heat corresponding to this saturation temperature is 2466 kJ/kg. Hence,
L.C.V. = (H.C.V. – x . 2466) kJ/kg
Here , ‘x’ – fraction of water vapor present in the products of combustion for 1 kg of fuel.
Fossil Fuels: Composition and Properties
Gaseous Fuels
Fuel Specific Gravity
% composition by weight HCV kJ/kg C H2 S
Petrol 0.74 85.4 14.6 - 46900
Paraffin 6.79 86.3 13.6 0.1 46500
Diesel Oil 0.87 86.3 12.8 0.9 46000
Heavy fuel oil 0.95 86.1 11.8 2.1 44000
Fuel Percentage Volumetric composition
Calorific Value kJ/m3
H2 CO CH C2H4 CO2 N2 HCV LCV
Coal Gas 27 7 48 13 3 2 31900 29000
Town Gas 55 14 23 2.5 2 3.5 19500 17500
Coke Oven gas 50 8 29 4 2 7 21300 19300
Producer Gas 6 23 3 0.2 5.8 62 5000 4800
Liquid Fuels
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Fuels: Performance Properties (2) Flash point
Lowest temperature at which a volatile substance can vaporize to for a ignitable mixture with air.
Different from Auto-ignition temperature which does not require an ignition source or Fire
point viz. temperature above which the fuel continues to burn after being ignited.
(3) Pour point
Lowest temperature at which the liquid becomes semisolid and loses its flow characteristics.
(4) Heat of formation
The free energy of chemical elements at 1 atm. 25 °C arbitrarily assumed to be zero.
Standard free energy of formation (Enthalpy of formation) of a compound, gf0 , is the
free energy change when one mole of the compound is formed directly from its
constituent elements.
The constituents are at 298 K & 1 atm. The value will be different at different conditions.
Compound ∆H˚ (J/ kg. mole) ∆G˚ (J/ kg. mole)
CO -110 x 106 -137 x 106
CO2 -394 x 106 -395 x 106
Water -286 x 106 -237 x 106
Fuels: Performance Properties (5) Octane Number Rating of SI engine fuels is based on its antiknock property. The property is compared with that of a mixture of iso‐octane (C8H18) nad
normal heptane (C7H16). Iso‐octane – rating 100, heptane‐ rating 0). Octane number is the percentage by volume of, iso‐octane in a mixture of iso‐
octane and normal heptane, which exactly matched the knocking intensity in a standard engine under standard conditions.
(6) Cetane Number Cetane number is the percentage by volume of normal cetane in mixture of
reference fuels that gives same knocking intensity as of the fuel under standard conditions.
Reference fuels are normal cetane (rating 100) and alpha methyl naphthalene (rating 0).
(7) Knocking Characteristics
Difference between time of injection and actual combustion termed as ‘ignition lag’.
Increase in ignition lag – increase in amount of fuel being accumulated in the cylinder. Hence,
combustion afterwards, leads to abnormal release of energy causing knocking.
Lag leads to problems in starting, warm up and exhaust smoke. Hence, high Cetane rating fuel
preferred.
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Fuels: Performance Properties
(9) Volatility
Depends on fractional composition of the fuel in terms of
hydrocarbon components.
Standard process of measuring the volatility of the fuel is by
distillation at atmospheric pressure, in presence of its vapor.
The fraction that boils off at a particular temperature is
measured.
Characteristic points – 10, 40, 50 & 90 % of fuel evaporation
and the temperature at which boiling ceases. Distillation curves for Petrol
(8) Antiknock Quality Abnormal burning causes unwanted temperature and pressure surges in the
cylinders, affects the efficiency. Antiknock quality resists the tendency for detonation during combustion. It depends on self ignition characteristics and composition of the fuel. Better SI engine – less knocking – higher compression ratios – better efficiency ‐
more power output.
(10) Starting and Warming up Certain part of the fuel should vaporize at room temperature for easy starting. Hence, the distillation curve temperature values for 0 ‐10 % boil off should be
relatively low. As the engine warms up, the temperature will gradually reach operating value. (11) Crankcase Dilution Liquid fuel in cylinders deteriorates oil quality or dilutes the oil causing weak oil
films between rubbing surfaces. So, the upper portion of distillation curve should have low boil off temperatures
so that all the fuel is vaporized before combustion. (12) Vapor Lock Characteristics Faster vaporization of fuel can affect the carburetor metering or stop fuel flow
due to vapor lock in passages. This requires the presence of high boiling point components throughout the
distillation curve, which contradicts the previous requirements. Hence, the about requirements must be optimized for desired temperature.
Fuels: Performance Properties
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(13) Sulphur Content Free sulphur, H2S and other such compounds may corrode the fuel lines and fuel
control devices. Sulphur may also combine with oxygen and later with water to form sulphurous
acid. Low ignition temperature of Sulphur can promote knocking. (14) Gum Deposits Storage of the fuel causes hydrocarbons or impurities to oxidize and form gum
like substances. These can hinder the normal operation of valves and piston rings.
(15) Corrosion and Wear
Should not damage the system in operation. Associated with presence of sulphur and impurities.
(16) Handling
Easily flow under wide range of conditions
Low Pour point.
High Flash and Fire point.
Fuels: Performance Properties
Analysis of fossil fuels
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Thermo‐Chemistry of Fuel‐air Mixture
Thermo‐chemistry which is the combining of thermodynamics with chemistry to predict such items as how much heat is released from a chemical reaction.
For the most part, this is from converting chemical energy into heat, so the discussion will be on reacting mixtures of gas which are involved in chemical combustion processes.
Fuels
There are a wide variety of fuels used for power and propulsion.
The chemical process in which a fuel, for example methane, is burned consists of (on a very basic
level - there are many intermediate reactions that need to be accounted for when computations of the
combustion process are carried out);
Reference:http://mit.edu/16.unified/www/FALL/thermodynamics/notes/node111.html
The reactions are carried out in air, which can be approximated as 21% O2 and 79% N2 . This
composition is referred to as theoretical air.
Gas ppm by volume Molecular weight Mole fraction Molar ratio
O2 209500 31.998 0.2095 1
N2 780900 28.012 0.7905 3.773
Ar 9300 38.948 - -
CO2 300 40.009 - -
Air 1000000 28.962 1 4.773
Principal Constitutes of Dry Air
O2 is the reactive component in the air.
Air (O2-21%, N2-79%).
For 1 mole O2 there is 3.773 mole of N2.
There are other components of air (e.g Argon, which is roughly 1%), but the results given using the
theoretical air approximation are more than adequate for our purposes. With this definition, for each
mole of , 3.76 (or 79/21) N2 moles of are involved:
Nitrogen is not part of the combustion process, it leaves the combustion chamber at the same
temperature as the other products.
At the high temperatures achieved in internal combustion engines (aircraft and automobile) reaction
does occur between the nitrogen and oxygen, which gives rise to oxides of nitrogen, although we will
not consider these reactions.
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Stoichiometric Combustion of Fuels Combustion is defined as high temperature oxidation of the combustible elements of
coal and fuel oil (presence of carbon, hydrogen and sulphur contents).
Basic equation of combustion can be given as:
In case of insufficient O2 , combustion will be incomplete and forms CO as given,
2C+O2=CO
Combustion is governed by a four letter word “MATT”‐
M‐Sufficient Mixture Turbulence,
A‐Proper Air‐Fuel Ratio,
T‐Temperature,
T‐ Enough Time for Combustion
The analysis of fuel is performed either by proximate (volume basis) analysis or by ultimate (mass balance) analysis.
The ultimate analysis of fuel (coal) shows the following components on mass basis: carbon (C), hydrogen (H), oxygen (O), nitrogen (N), moisture (M) and ash (A). Therefore,
C+H+O+N+M+A=1.0
The mass of oxygen needed for oxidation process are calculated as follows:
i. C (12 kg) + O2 (32 kg) = CO2 (44 kg)
C (C kg) + O2 (2.67C kg) = CO2 (3.67C kg)
ii. 2H2 (4kg) + O2 (32kg) = 2H2O (36kg)
2 H2 (H kg) + O2 (8H kg) = 2H2O (9Hkg)
iii. S (32kg) + O2 (32kg) = SO2 (64kg)
S (S kg) + O2 (S kg) = SO2 (2S kg)
Mass of oxygen required for complete combustion of 1kg of fuel:
mO2=2.67C + 8H + S ‐ O
Theoretically air required for complete combustion of 1kg of fuel:
Air‐fuel ratio =
Stoichiometric Combustion of Fuels
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Complete combustion of fuel cannot be achieved without applying excess air than stoichiometric.
Percentage of excess air can be given as;
Where maa is the actual air supplied for complete combustion of 1kg of fuel.
For large utility boiler, percentage of excess air varies from 15 to 30%.
Combustion Equation
Find out the combustion equation based on ultimate analysis of fuel and volumetric analysis of combustion products, consider the following example:
C=62% , H=4% , S=3% , O=4%
The exhaust gas has following volumetric analysis;
Let a mole of oxygen be supplied for 100 kg fuels, combustion equation may be written as‐
Stoichiometric Combustion of Fuels
By equating the coefficients of C, H, N, S, O2 and N2 the constants can be evaluated.
For example , consider the of propane gas with stoichiometric air.
Stoichiometric Combustion of Fuels
With 80% theoretical air, above equation becomes with addition of formation of carbon monoxide
due to incomplete combustion.
Carbon balance gives: 3=a + b
Oxygen balance gives: 8=a + 2b + 4
By solving: a=2, b=1 ,combustion equation is-
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IIT Kanpur Kanpur, India (208016)
Alternative Fuels & Advance in IC Engines
Course Instructor Dr. Avinash Kumar Agarwal
Professor Department of Mechanical Engineering
Indian Institute of Technology Kanpur, Kanpur
Petroleum and it’s Refining
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History of Crude Oil
3000 BC Sumerians use asphalt as an adhesive; Egyptians use pitch to grease chariot wheels;
Mesopotamians use bitumen to seal boats.
600 BC Confucius writes about drilling a 100 feet gas well and using bamboo for pipes
1500 AD Chinese dig oil wells >2000 feet deep
1847 First “rock oil” refinery in England
1849 Canada distills kerosene from crude oil
1856 World’s first refinery in Romania
1857 Flat-wick kerosene lamp invented
1859 Pennsylvania oil boom begins with 69 feet oil well producing 35 bpd
1860-61 Refineries built in Pennsylvania and Arkansas
1870 US Largest oil exporter; oil was US 2nd biggest export
1878 Thomas Edison invents light bulb
1901 Spindle top, Texas producing 100,000 bpd kicks off modern era of oil refining
1908 Model T’s sell for $950/T
1913 Gulf Oil opens first drive-in filling station
1942 First Fluidized Catalytic Cracker (FCC) commercialized
1970 First Earth Day; EPA passes Clean Air Act
2005 US Refining capacity is 17,042,000 bpd, 23% of World’s capacity
Crude Oil: Formation and Exploration
Formation– Dead marine animals and plant matter accumulated over
millions of years, transformed into oil in sedimentary rocks due to heat
and pressure.
Deposits found beneath the crust, have a water body below and
pressurized natural gas above.
Thick and dense rock layer seals of the deposit, ensuring no leakage.
Advanced Petroleum Drilling
Drilling through the rock layer causes pressure release, pushing oil and
gas to surface. When pressure is attenuated, oil can be pumped up.
Conventional Petroleum Drilling
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Various Sources of Petroleum and Drilling Arrangement
Introduction of Crude Oil
Our modern technological society relies very heavily on fossil fuels (crude oil) as an important source
of energy.
Crude oil (known as black gold) is a thick, dark brown or greenish flammable liquid, which is found in
the upper strata of some regions of the Earth's crust.
It is a complex mixture of various hydrocarbons along with traces of other chemicals and compounds.
Crude oil can be categorized as either "sweet crude" (where the sulphur content less than 0.5%) or
"sour crude," (where the sulphur content is at least 2.5%).
Crude oil must undergo several separation processes so that its components can be obtained and
used as fuels or converted to more valuable products such as petrol for cars, fuel oil for heating, diesel
fuels for heavy transport, bitumen for roads.
The process of transforming crude oil into finished petroleum products (that the market demands) is
called crude oil refining.
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Introduction of Crude Oil Products
Petroleum products are produced from the
processing of crude oil at petroleum refineries
and the extraction of liquid hydrocarbons at
natural gas processing plants.
Petroleum is the broad category that includes
both crude oil and petroleum products.
The main goal of petroleum refining is to take
the undesirable components of the crude oil
and upgrade them into more valuable products.
Petroleum refining results in greater output
than the input because of changes in the overall
density of the refined products relative to that
of the input oils.
Gasoline, diesel, and jet fuel are among the
most valuable products, whereas fuel oils and
lubricants are sometimes sold at a loss. Petroleum Products
Petroleum based liquid fuels
Crude petroleum is a mixture of large number of hydrocarbon compounds differing widely in:-
Molecular structure
Sulphur, oxygen, nitrogen content
Impurities
For purpose of comparison, it is desirable to arrange these hydrocarbon compounds into families
based on the hydrogen and carbon arrangement within the molecules.
Family General Formula Molecular Arrangement
Paraffins CnH2n + 2 Chain
Olefins CnH2n Chain
Di‐olefins CnH2n‐2 Chain
Naphthene CnH2n Ring
Aromatics CnH2n‐6 Ring
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Paraffins. The normal paraffin hydrocarbons consist of straight chain (open chain) molecular
structure. Straight chain paraffins are termed as saturated compounds and are characteristically very
stable.
Another variation of the paraffin family consists of an open chain structure with an attached branch, and
is usually termed branch chain paraffin.
Isobutane, shown above, is an example of this type. This is also a saturated compound and is very stable.
The branch chain paraffins have good antiknock qualities when used as SI engine fuels.
Olefins are chain compounds similar to paraffins, but are unsaturated because they contain one
double carbon to carbon bond. A typical example is butene. Olefins are not as stable as the single
bond paraffins due to presence of double bond. Crude oil does not contain olefins and these result
from certain refinery processes.
Diolefins: are olefins with two double bonds. They are unsaturated and rather unstable.
Naphthenes: have same general formula as olefins but have ring structure. Cyclopentane is a
typical naphthene.
Aromatics: Ring structure compounds based on the benzene ring. A double bond indicates
unsaturation. For e.g.: Benzene
Butadiene Cyclopentane Benzene
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Characteristics of these families
The anti-knock quality of a fuel when used in a SI engine appears to be poorest in the normal
paraffins and improves generally in the order Olefins, Diolefins, Naphthenes, Aromatics.
The suitability of these fuels for CI engine is in the inverse order of their suitability for SI engine. For
CI engine, normal paraffins are better fuels and aromatics are the least desirable.
In general, as the number of atoms in the molecular structure increases, the boiling point
temperature rises.
As the proportion of the hydrogen atoms to carbon atoms in the molecule increases, the heating value
generally increases. Paraffins have greatest heating value and aromatic least.
Refining of Petroleum.
Crude petroleum is rarely used as fuel for IC engines.
Petroleum is purified and separated into different usable components before various applications.
The process of separating petroleum into useful fractions and removal of undesirable impurities is
called refining.
While the modern refinery is a very complex chemical processing plant, it is nevertheless based on
the simple fact that the constituents of crude petroleum have different boiling points varying roughly
with their molecular weight.
Before the crude oil is subjected to refining, it is passed under pressure into cylindrical tanks to
remove gas, oil and sand particles.
It is then washed with acid and alkali solutions one after the other to remove basic and acidic
impurities respectively.
It then undergoes the refining process through the process of fractional distillation.
This process works on the variation of boiling points of different components of crude oil.
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The components having higher boiling points are separated out at lower levels while those with lower
boiling points are removed at higher levels. The condensed fractions in each tray are tapped off
continuously. Each of these fractions covers a certain boiling point range, and each may be further
refined by separate fractionating within a narrow range of boiling points.
The various fractions obtained by the fractional distillation of crude petroleum oil are asphalt,
lubricating oil, paraffin wax, fuel oil, diesel oil, kerosene, petrol and petroleum gas. Except for
asphalt, lubricating oil and paraffin wax, all other fractions readily burn producing heat.
The yield of some of the petroleum products from the fractional distillation process does not always
coincide with the commercial demand for such products. Economic necessity usually dictates the
need for conversion of some of the products in small demand into products for which the demand is
greater. To cope with the situation, various processes are used to convert some of these fractions to
compounds.
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Cracking consists of breaking down large and complex molecules into lighter and simpler compounds with lower boiling
points. Thermal cracking subjects the heavy hydrocarbons to high temperatures and pressures. Catalytic cracking is
accomplished at somewhat lower temperatures and pressures, but in the presence of a catalyst and generally produces a fuel
with higher anti-knock qualities.
Hydrogenation differs from the cracking process in that hydrogen atoms are added to certain hydrocarbons, under high
pressure and temperature, to produce more desirable compounds. This process is often used to convert unstable to stable
compounds.
Polymerization brings together light, unsaturated gases of one family, in the presence of a catalyst, to produce a liquid.
Alkylation combines light gases of different families in the presence of a catalyst. Generally an olefin is combined with
paraffin in this process to give branch chain paraffins.
Isomerization changes the relative position of the atoms within the molecules of a hydrocarbon without changing its
molecular formula. It produces isomers of the original hydrocarbon.
Cyclization essentially joins together the ends of straight chain molecules to form a ring compound of the naphthene family.
Aromatization is a process similar to cyclization except that the product is an aromatic compound.
Reforming is a type of cracking process in which naphtha or straight gasoline is converted into gasoline of higher octane
rating.
Blending is a process of mixing refinery products to obtain a commercial product of desired quality.
Various processes used to convert some of these fractions to compounds are:-
Rating of SI engine fuels
Hydrocarbon fuels used in SI engine have a tendency, when engine operating conditions become
severe, to cause engine knock. Factors such as load, speed spark advance, A/F ratio and temperature
in the later stages of combustion effect knocking.
A fuel will have an increasing tendency to knock with increasing compression ratio.
The rating of a particular fuel is accomplished by comparing its performance with that of a standard
reference fuel which is usually a combination of iso- octane and normal heptane plus tetraethyl lead.
Iso-octane, being a very good anti-knock fuel is arbitrarily assigned a rating of 100 octane number.
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Rating of SI engine fuels
Normal heptane, on the other hand, has very poor anti-knock qualities and is given a rating of zero
octane number. Octane number rating is an expression which indicates the ability of a fuel to resist
knock in a SI engine.
The higher the octane number rating of a fuel, the greater will be its resistance to knock, and the
higher will be the compression ratio which may be used without knock.
A blend of isooctane and n-heptane is used to test octane numbers below 100 octane; the octane
number is given as the percentage of isooctane in the blend. For example, if the blend contains 95%
isooctane and 5% n-heptane, the blend has a 95 octane rating. Octane numbers above 100 octane can
be tested by adding specific amounts of tetraethyl lead to isooctane to make reference fuel blends
above 100 octane.
Important qualities of SI engine fuels Volatility: Gasoline is a mixture of many hydrocarbons with different boiling points. The
constituents will boil off at wide range of temperatures. It effect phase of operation and maintenance. Volatility effects:-
Starting and warming up: For ease of starting it is necessary to have some of the gasoline vaporize at the starting temperatures.
Operating range performance, acceleration and distribution: It is desirable to have low distillation temperatures in the engine operating range, in order to obtain good vaporization of the gasoline. Better vaporization means more uniform distribution of fuel to the cylinder and better acceleration characteristics.
Crankcase dilution: Liquid gasoline in the cylinder is undesirable since it washes away oil from the cylinder walls. The loss of oil impairs lubrication and tend to cause damage to the engine through increased friction between the piston rings and the cylinder. To prevent this, upper portion of the distillation curve should exhibit sufficiently low distillation temperatures to insure that all of the gasoline in the cylinder will be vaporized.
Vapor lock characteristics: Higher rate of vaporization can upset the carburetor metering or even stop the fuel flow to the engine, by setting up a vapor lock in the fuel passages. This characteristics makes it desirable to have high boiling off temperatures throughout the distillation range.
Winter and summer gasoline: Because of higher atmospheric temprature encountered during the summer months, commercial refiners usually reduce the volatility of the automotive gasoline intended for warm weather consumption.
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Important qualities of SI engine fuels
Gum deposits: Certain unsaturated hydrocarbon have an inclination to oxidize during stroage and
form a product known as gum. The gum in the fuel, in turn, tends to cause deposits on the intake
valve, piston rings and other engine parts.
Sulphur contents: Due to corrosive nature of sulphur, gasoline specification limits the permissible
quantity of sulphur.
Anti-Knock quality: The SI fuel should have anti-knock properties to prevent damage to the
engine.
Important qualities of CI engine fuels
Ignition quality: Knocking in CI engine is due to sudden ignition and abnormal rapid combustion of
accumulated fuel in the combustion chamber. This is because of long ignition lag. As the ignition lad
increases, the amount of fuel accumulated in the combustion chamber, before combustion commences, also
increases.
When combustion actually takes place, abnormal amount of energy are suddenly released, causing an
excessive rate of pressure rise which is an audible knock. CI engine knock can be controlled by decreasing
ignition lag. The shorter the ignition lag, the less is tendency to knock.
Volatility: The fuel should be sufficiently volatile in the operating temperature range to produce good
mixing and combustion and thus reduce objectionable smoke and odor in the exhaust.
Viscosity: CI engine fuel is more viscous than SI engine fuel. They should however be able to flow through
the systems and strainers under the lowest operating condition.
Impurities: CI engine fuels have a tendency to contain more solid particles than SI engine fuels. These
should be minimum to reduce a minimum excessive engine wear.
Flash Point: The flash point should be sufficiently high to prevent fire hazard.
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Introduction of Oil Refinery
A refinery is a complex chemical plant that utilizes several different techniques to take a very rough
feedstock, crude oil, and converts it into desirable products, such as gasoline, diesel etc.
Oil companies invest large sums of capital into these refineries in hopes of making a large profit.
Today, crude oil is refined all over the world. The largest oil refinery is the Paraguana Refining
Complex in Venezuela, which can process 940,000 barrels of oil each day.
In fact, most of the oil industry’s largest refineries are in Asia and South America. Nevertheless, the
practice of refining oil was created in the United States, where it continues to be an important part of
the nation’s economy.
Petroleum Refining Process
A petroleum refinery is a chemical plant that processes crude oil and produces several valuable
products. A refinery contains different types of units that perform a variety of different operations.
The main goal is to take the undesirable components of the crude oil and upgrade them into more
valuable products.
At the top of the distillation column
At the bottom of the distillation column
Short carbon chains Long carbon chains
Light molecules Heavy molecules
Low boiling points High boiling points
Gases & very runny liquids
Thick, viscous liquids
Very volatile Low volatility
Light colour Dark colour
Highly flammable Not very flammable
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Crude Oil Refining Stages
Detailed crude oil refining can be divided into following three categories:
(i) Separation Units
(ii) Finishing Units
(iii) Conversion
Refined Petroleum Products
Products refined from the liquid fractions of crude oil can be placed into ten main categories. These
main products are further refined to create materials more common to everyday life.
The ten main products of petroleum are:
(i) Asphalt
(ii) Diesel
(iii) Fuel Oil
(iv) Gasoline
(v) Kerosene
(vi) Liquefied Petroleum Gas (LPG)
(vii) Lubricating Oil
(viii) Paraffin Wax
(ix) Bitumen
(x) Petrochemicals
In all above mentioned products, gasoline and diesel are the major constituent. Both of them are
mainly used for automotive applications.
Jet fuel is the other major faction used for used for aviation application.
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Refined Petroleum Products
Asphalt
Asphalt is commonly used to make roads.
It is a colloid of asphaltenes and maltenes that is separated from the other components of crude oil by
fractional distillation.
Asphalt is usually stored and transported at around 300°F.
Diesel
Diesel is any fuel that can be used in a diesel engine.
Diesel is produced by fractional distillation between 392°F and 662°F.
Diesel has a higher density than gasoline and is simpler to refine from crude oil. It is most commonly
used in transportation.
Fuel Oil
Fuel oil is any liquid petroleum product that is burned in a furnace to generate heat.
Fuel oil is also the heaviest commercial fuel that is produced from crude oil.
The six classes of fuel oil are: distillate fuel oil, diesel fuel oil, light fuel oil, gasoil, residual fuel oil, and
heavy fuel oil.
Residual fuel oil and heavy fuel oil are known commonly as navy special fuel oil and bunker fuel; both
of these are often called furnace fuel oil.
Refined Petroleum Products
Gasoline
Almost half of all crude oil refined, is made into gasoline. It is used as fuel in IC engines.
Gasoline is a mixture of paraffins, naphthenes, and olefins, although the specific ratios of these parts
depend on the refinery where the crude oil is processed.
Gasoline is called different things in different parts of the world. Some of these names are: petrol,
petroleum spirit, gas, petro-gasoline, and mo-gas.
Kerosene
Kerosene is collected through fractional distillation at temperatures between 302° F and 527°F.
It is a combustible liquid that is thin and clear. Kerosene is most commonly used as jet fuel and as
heating fuel.
In the early days of oil, kerosene replaced whale oil in lanterns. Now, kerosene is used as fuel in
portable stoves, kerosene space heaters, and in liquid pesticides.
Liquefied Petroleum Gas (LPG)
Liquefied petroleum gas is a mixture of gases that are most often used in heating appliances, aerosol
propellants, and refrigerants.
Different kinds of liquefied petroleum gas, or LPG, are propane and butane.
At normal atmospheric pressure, liquefied petroleum gas will evaporate, so it needs to be contained
in pressurized steel bottles.
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Refined Petroleum Products
Lubricating Oil
Lubricating oils consist of base oils and additives.
Different lubricating oils are classified as paraffinic, naphthenic, or aromatic. The most commonly-
known lubricating oil is motor oil, which protects moving parts inside an internal combustion engine.
Paraffin Wax
Paraffin wax is a white, odorless, tasteless, waxy solid at room temperature. The melting point of
paraffin wax is between 117°F and 147°F, depending on other factors.
It is an excellent electrical insulator, second only to Teflon, a specialized product of petroleum.
Paraffin wax is used in drywall to insulate buildings.
Bitumen
Bitumen, commonly known as tar, is a thick, black, sticky material. Refined bitumen is the bottom
fraction obtained by the fractional distillation of crude oil.
Bitumen is used in paving roads and waterproofing roofs and boats. Bitumen is also made into thin
plates and used to soundproof dishwashers and hard drives in computers.
Petrochemicals
Petrochemicals are the chemical products made from the raw materials of petroleum.
These chemicals include: ethylene, used to make anesthetics, antifreeze, and detergents; propylene,
used to produce acetone and phenol; benzene, used to make other chemicals and explosives; toluene,
used as a solvent and in refined gasoline; and xylene is used as a solvent and cleaning agent.
Refined Petroleum Products
Name Number of
Carbon Atoms Boiling Point
(°C) Uses
Refinery Gas 3 or 4 below 30 Bottled gas (propane or butane).
Gasoline 7 to 9 100 to 150 Fuel for car engines.
Naphtha 6 to 11 70 to 200 Solvents and used in gasoline.
Kerosene (paraffin) 11 to 18 200 to 300 Fuel for aircraft and stoves.
Diesel Oil 11 to 18 200 to 300 Fuel for road vehicles and trains.
Lubricating Oil 18 to 25 300 to 400 Lubricant for engines and machines.
Fuel Oil 20 to 27 350 to 450 Fuel for ships and heating.
Greases and Wax 25 to 30 400 to 500 Lubricants and candles.
Bitumen above 35 above 500 Road surface and roofing.
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