Fuels & Combustionlibvolume2.xyz/.../fuelsandcombustionpresentation2.pdf1 Training Session on Energy Equipment Fuels & Combustion Presentation from the “Energy Efficiency Guide for

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Training Session on Energy

Equipment

Fuels & Combustion

Presentation from the

“Energy Efficiency Guide for Industry in Asia”

www.energyefficiencyasia.org

© UNEP 2006

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© UNEP 2006

Training Agenda: Fuels &

Combustion

Introduction

Type of fuels

Performance evaluation

Energy efficiency opportunities

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Introduction

• Solar energy is converted to

chemical energy through photo-

synthesis in plants

• Energy produced by burning wood or

fossil fuels

• Fossil fuels: coal, oil and natural gas

The Formation of Fuels

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Combustion

Introduction

Type of fuels



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Type of Fuels

Liquid Fuels

� Usage

• Used extensively in industrial applications

� Examples

• Furnace oil

• Light diesel oil

• Petrol

• Kerosine

• Ethanol

• LSHS (low sulphur heavy stock)

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Type of Fuels

Liquid Fuels

� Density

• Ratio of the fuel’s mass to its volume at 15 oC,

• kg/m3

• Useful for determining fuel quantity and quality

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Type of Fuels

Liquid Fuels

� Specific gravity

• Ratio of weight of oil volume to weight of same

water volume at a given temperature

• Specific gravity of water is 1

• Hydrometer used to measure

Fuel oil

type

LDO

(Light Diesel Oil)

Furnace oil LSHS (Low Sulphur

Heavy Stock)

Specific

Gravity

0.85-0.87 0.89-0.95 0.88-0.98

Table 1. Specific gravity of various fuel oils (adapted

from Thermax India Ltd.)

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Type of Fuels

Liquid Fuels

� Viscosity

• Measure of fuel’s internal resistance to flow

• Most important characteristic for storage and use

• Decreases as temperature increases

� Flash point

• Lowest temperature at which a fuel can be

heated so that the vapour gives off flashes when

an open flame is passes over it

• Flash point of furnace oil: 66oC

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Type of Fuels

Liquid Fuels

� Pour point

• Lowest temperature at which fuel will flow

• Indication of temperature at which fuel can be

pumped

� Specific heat

• kCal needed to raise temperature of 1 kg oil by

1oC (kcal/kgoC)

• Indicates how much steam/electricity it takes to

heat oil to a desired temperature

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Type of Fuels

Liquid Fuels

� Calorific value

• Heat or energy produced

• Gross calorific value (GCV): vapour is fully

condensed

• Net calorific value (NCV): water is not fully

condensed

Fuel Oil Gross Calorific Value (kCal/kg)Kerosene 11,100

Diesel Oil 10,800L.D.O 10,700

Furnace Oil 10,500

LSHS 10,600

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Type of Fuels

Liquid Fuels

� Sulphur content

• Depends on source of crude oil and less on the

refining process

• Furnace oil: 2-4 % sulphur

• Sulphuric acid causes corrosion

� Ash content

• Inorganic material in fuel

• Typically 0.03 - 0.07%

• Corrosion of burner tips and damage to materials

/equipments at high temperatures

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Type of Fuels

Liquid Fuels

� Carbon residue

• Tendency of oil to deposit a carbonaceous solid

residue on a hot surface

• Residual oil: >1% carbon residue

� Water content

• Normally low in furnace oil supplied (<1% at

refinery)

• Free or emulsified form

• Can damage furnace surface and impact flame

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Type of Fuels

Liquid Fuels

� Storage of fuels

• Store in cylindrical tanks above or below

the ground

• Recommended storage: >10 days of

normal consumption

• Cleaning at regular intervals

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Type of Fuels

Liquid Fuels

Properties Fuel Oils

Furnace Oil L.S.H.S L.D.O

Density (Approx. g/cc at 150C)

0.89-0.95 0.88-0.98 0.85-0.87

Flash Point (0C) 66 93 66

Pour Point (0C) 20 72 18

G.C.V. (Kcal/kg) 10500 10600 10700

Sediment, % Wt. Max.

0.25 0.25 0.1

Sulphur Total, % Wt. Max.

< 4.0 < 0.5 < 1.8

Water Content, % Vol. Max.

1.0 1.0 0.25

Ash % Wt. Max. 0.1 0.1 0.02

Typical specifications of fuel oils(adapted from Thermax India Ltd.)

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Type of Fuels

Solid Fuels

� Coal classification

• Anthracite: hard and geologically the

oldest

• Bituminous

• Lignite: soft coal and the youngest

• Further classification: semi- anthracite,

semi-bituminous, and sub-bituminous

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Type of Fuels

Solid Fuels

� Physical properties

• Heating or calorific value (GCV)

• Moisture content

• Volatile matter

• Ash

� Chemical properties

• Chemical constituents: carbon, hydrogen, oxygen, sulphur

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Type of Fuels

Solid Fuels (Physical properties)

� Heating or calorific value

• The typical GVCs for various coals are:

Parameter Lignite

(Dry

Basis)

Indian

Coal

Indonesian

Coal

South

African

Coal

GCV

(kCal/kg)

4,500 4,000 5,500 6,000

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Type of Fuels


� Moisture content

• % of moisture in fuel (0.5 – 10%)

• Reduces heating value of fuel

• Weight loss from heated and then cooled powdered

raw coal

� Volatile matter

• Methane, hydrocarbons, hydrogen, CO, other

• Typically 25-35%

• Easy ignition with high volatile matter

• Weight loss from heated then cooled crushed coal

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Type of Fuels


� Ash

• Impurity that will not burn (5-40%)

• Important for design of furnace

• Ash = residue after combustion

� Fixed carbon

• Fixed carbon = 100 – (moisture + volatile matter + ash)

• Carbon + hydrogen, oxygen, sulphur, nitrogen

residues

• Heat generator during combustion

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Type of Fuels


� Proximate analysis of coal

• Determines only fixed carbon, volatile matter,

moisture and ash

• Useful to find out heating value (GCV)

• Simple analysis equipment

� Ultimate analysis of coal

• Determines all coal component elements: carbon,

hydrogen, oxygen, sulphur, other

• Useful for furnace design (e.g flame temperature,

flue duct design)

• Laboratory analysis

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Type of Fuels


� Proximate analysis

Typical proximate analysis of various coals (%)

Indian

Coal

Indonesian

Coal

South African

Coal

Moisture 5.98 9.43 8.5

Ash 38.63 13.99 17

Volatilematter

20.70 29.79 23.28

FixedCarbon 34.69 46.79 51.22

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Type of Fuels

Solid Fuels (Chemical Properties)

� Ultimate analysis

Typical ultimate analysis of coal (%)

Parameter Indian Coal, % Indonesian Coal, %

Moisture 5.98 9.43

Mineral Matter (1.1 x Ash) 38.63 13.99

Carbon 41.11 58.96

Hydrogen 2.76 4.16

Nitrogen 1.22 1.02

Sulphur 0.41 0.56

Oxygen 9.89 11.88

GCV (kCal/kg) 4000 5500

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Type of Fuels

Solid Fuels (Chemical Properties)

� Storage, Handling & Preparation

• Storage to minimize carpet loss and loss due

to spontaneous combustion

• Reduce carpet loss: a) a hard surface b)

standard concrete/brick storage bays

• Coal preparation before use is important for

good combustion

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Type of Fuels

Gaseous Fuels

� Advantages of gaseous fuels

• Least amount of handling

• Simplest burners systems

• Burner systems require least

maintenance

• Environmental benefits: lowest GHG

and other emissions

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Type of Fuels

Gaseous Fuels

� Classification of gaseous fuels

(A) Fuels naturally found in nature

-Natural gas

-Methane from coal mines

(B) Fuel gases made from solid fuel

-Gases derived from coal

-Gases derived from waste and biomass

-From other industrial processes

(C) Gases made from petroleum

-Liquefied Petroleum gas (LPG)

-Refinery gases

-Gases from oil gasification

(D) Gases from some fermentation

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Type of Fuels

Gaseous Fuels

� Calorific value

• Fuel should be compared based on the net

calorific value (NCV), especially natural gas

Typical physical and chemical properties of various gaseous fuels

Fuel

Gas

Relative

Density

Higher Heating

Value kCal/Nm3

Air/Fuel

ratio m3/m3

Flame

Temp oC

Flame

speed m/s

Natural Gas

0.6 9350 10 1954 0.290

Propane 1.52 22200 25 1967 0.460

Butane 1.96 28500 32 1973 0.870

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Type of Fuels

Gaseous Fuels

� Liquefied Petroleum Gas (LPG)

• Propane, butane and unsaturates, lighter C2

and heavier C5 fractions

• Hydrocarbons are gaseous at atmospheric

pressure but can be condensed to liquid state

• LPG vapour is denser than air: leaking gases

can flow long distances from the source

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Type of Fuels

Gaseous Fuels

� Natural gas

• Methane: 95%

• Remaing 5%: ethane, propane, butane, pentane,

nitrogen, carbon dioxide, other gases

• High calorific value fuel

• Does not require storage facilities

• No sulphur

• Mixes readily with air without producing smoke or

soot

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Type of Fuels

Comparing Fuels

Fuel Oil Coal Natural

Gas

Carbon 84 41.11 74

Hydrogen 12 2.76 25

Sulphur 3 0.41 -

Oxygen 1 9.89 Trace

Nitrogen Trace 1.22 0.75

Ash Trace 38.63 -

Water Trace 5.98 -

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Combustion

Introduction

Type of fuels



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Performance Evaluation

• Combustion: rapid oxidation of a fuel

• Complete combustion: total oxidation of fuel (adequate supply of oxygen needed)

• Air: 20.9% oxygen, 79% nitrogen and other

• Nitrogen: (a) reduces the combustion

efficiency (b) forms NOx at high temperatures

• Carbon forms (a) CO2 (b) CO resulting in less heat production

Principles of Combustion

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• Control the 3 Ts to optimize combustion:

• Water vapor is a by-product of burning fuel

that contains hydrogen and this robs heat

from the flue gases

Principles of Combustion

1T) Temperature

2T) Turbulence

3T) Time

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Oxygen is the key to combustion

Principle of Combustion

Bureau of Energy Efficiency, India, 2004

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Stochiometric calculation of air

required

� Stochiometric air needed for combustion of

furnace oil

� Theoretical CO2 content in the flue gases

� Actual CO2 content and % excess air

� Constituents of flue gas with excess air

� Theoretical CO2 and O2 in dry flue gas by

volume

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• Measure CO2 in flue gases to estimate

excess air level and stack losses

Concept of Excess Air

Carbon dioxide (%)

Excess air (%)

Source: Bureau of Energy Efficiency, India, 2004

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Concept of Excess Air

Residual oxygen (%)

Excess air (%)

Bureau of Energy Efficiency, India, 2004

• Measure O2 in flue gases to estimate

excess air level and stack losses

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� To exhaust combustion products to

atmosphere

� Natural draft:

• Caused by weight difference between the hot gases

inside the chimney and outside air

• No fans or blowers are used

� Mechanical draft:

• Artificially produced by fans

• Three types a) balanced draft, b) induced draft and c)

forced draft

Draft System

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Combustion

Introduction

Type of fuels



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Energy Efficiency Opportunities

� Preheating of combustion oil

� Temperature control of combustion

oil

� Preparation of solid fuels

� Combustion controls

Four main areas

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� Purpose: to make furnace oil easier

to pump

� Two methods:

• Preheating the entire tank

• Preheating through an outflow heater as the oil flows out

Preheating of Combustion Oil

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� To prevent overheating

• With reduced or stopped oil flow

• Especially electric heaters

� Using thermostats

Temperature Control of

Combustion Oil

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Sizing and screening of coal

• Important for efficient combustion

• Size reduction through crushing and pulverizing (< 4 - 6 mm)

• Screen to separate fines and small particles

• Magnetic separator for iron pieces in coal

Preparation of Solid Fuels

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Conditioning of coal:

• Coal fines cause combustion problems

• Segregation can be reduced by conditioning coal with water

• Decrease % unburnt carbon

• Decrease excess air level required


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Blending of coal

• Used with excessive coal fines

• Blending of lumped coal with coal containing fines

• Limits fines in coal being fired to <25%

• Ensures more uniform coal supply


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• Assist burner to achieve optimum boiler

efficiency through the regulation of fuel

supply, air supply, and removal of

combustion gases

• Three controls:

• On/Off control: burner is firing at full rate or it is

turned off

• High/Low/Off control: burners with two firing rates

• Modulating control: matches steam pressure

demand by altering the firing rate

Combustion Controls

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Training Session on Energy

Equipment

Fuels & Combustion

THANK YOU

FOR YOUR ATTENTION

© UNEP GERIAP

�

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© UNEP 2006

Disclaimer and References

• This PowerPoint training session was prepared as part of

the project “Greenhouse Gas Emission Reduction from

Industry in Asia and the Pacific” (GERIAP). While

reasonable efforts have been made to ensure that the

contents of this publication are factually correct and

properly referenced, UNEP does not accept responsibility for

the accuracy or completeness of the contents, and shall not

be liable for any loss or damage that may be occasioned

directly or indirectly through the use of, or reliance on, the

contents of this publication. © UNEP, 2006.

• The GERIAP project was funded by the Swedish

International Development Cooperation Agency (Sida)

• Full references are included in the textbook chapter that is

available on www.energyefficiencyasia.org

Documents

Fuels & Combustionlibvolume2.xyz/.../fuelsandcombustionpresentation2.pdf1 Training Session on Energy Equipment Fuels & Combustion Presentation from the “Energy Efficiency Guide for