Transcript Document

Training Session on Energy
Equipment
Fuels & Combustion
Presentation from the
“Energy Efficiency Guide for Industry in Asia”
www.energyefficiencyasia.org
1
© UNEP 2006
Training Agenda: Fuels &
Combustion
Introduction
Type of fuels
Performance evaluation
Energy efficiency opportunities
2
© UNEP 2006
Introduction
The Formation of Fuels
• Solar energy is converted to
chemical energy through photosynthesis in plants
• Energy produced by burning wood or
fossil fuels
• Fossil fuels: coal, oil and natural gas
3
© UNEP 2006
Training Agenda: Fuels &
Combustion
Introduction
Type of fuels
Performance evaluation
Energy efficiency opportunities
4
© UNEP 2006
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)
5
© UNEP 2006
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
6
© UNEP 2006
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
Table 1. Specific gravity of various fuel oils (adapted
from Thermax India Ltd.)
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
7
© UNEP 2006
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
8
© UNEP 2006
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
9
© UNEP 2006
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
Kerosene
Diesel Oil
L.D.O
Furnace Oil
LSHS
Gross Calorific Value (kCal/kg)
11,100
10,800
10,700
10,500
10,600
10
© UNEP 2006
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
11
© UNEP 2006
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
12
© UNEP 2006
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
13
© UNEP 2006
Type of Fuels
Liquid Fuels
Typical specifications of fuel oils
(adapted from Thermax India Ltd.)
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
14
0.1
0.02
© UNEP 2006
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
15
© UNEP 2006
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
16
© UNEP 2006
Type of Fuels
Solid Fuels (Physical properties)
 Heating or calorific value
• The typical GVCs for various coals are:
Parameter
GCV
(kCal/kg)
Lignite
(Dry
Basis)
Indian
Coal
Indonesian
Coal
4,500
4,000
5,500
South
African
Coal
6,000
17
© UNEP 2006
Type of Fuels
Solid Fuels (Physical properties)
 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
18
© UNEP 2006
Type of Fuels
Solid Fuels (Physical properties)
 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
19
© UNEP 2006
Type of Fuels
Solid Fuels (Physical properties)
 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
20
© UNEP 2006
Type of Fuels
Solid Fuels (Physical properties)
 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
Volatile
matter
20.70
29.79
23.28
Fixed Carbon
34.69
46.79
51.22
21
© UNEP 2006
Type of Fuels
Solid Fuels (Chemical Properties)
 Ultimate analysis
Typical ultimate analysis of coal (%)
Parameter
Moisture
Mineral Matter (1.1 x Ash)
Carbon
Hydrogen
Nitrogen
Sulphur
Oxygen
GCV (kCal/kg)
Indian Coal, %
5.98
38.63
41.11
2.76
1.22
0.41
9.89
4000
Indonesian Coal, %
9.43
13.99
58.96
4.16
1.02
0.56
11.88
5500
22
© UNEP 2006
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
23
© UNEP 2006
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
24
© UNEP 2006
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
25
© UNEP 2006
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
26
© UNEP 2006
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
27
© UNEP 2006
Type of Fuels
Gaseous Fuels
 Natural gas
• Methane: 95%
• Remaing 5%: ethane, propane, butane,
nitrogen, carbon dioxide, other gases
pentane,
• High calorific value fuel
• Does not require storage facilities
• No sulphur
• Mixes readily with air without producing smoke or
soot
28
© UNEP 2006
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
-
29
© UNEP 2006
Training Agenda: Fuels &
Combustion
Introduction
Type of fuels
Performance evaluation
Energy efficiency opportunities
30
© UNEP 2006
Performance Evaluation
Principles of Combustion
• 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
31
© UNEP 2006
Performance Evaluation
Principles of Combustion
• Control the 3 Ts to optimize combustion:
1T) Temperature
2T) Turbulence
3T) Time
• Water vapor is a by-product of burning fuel
that contains hydrogen and this robs heat
from the flue gases
32
© UNEP 2006
Performance Evaluation
Principle of Combustion
Oxygen is the key to combustion
Bureau of Energy Efficiency, India, 2004
33
© UNEP 2006
Performance Evaluation
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
34
© UNEP 2006
Performance Evaluation
Concept of Excess Air
Excess air (%)
• Measure CO2 in flue gases to estimate
excess air level and stack losses
Carbon dioxide (%)
Source: Bureau of Energy Efficiency, India, 2004
35
© UNEP 2006
Performance Evaluation
Concept of Excess Air
Excess air (%)
• Measure O2 in flue gases to estimate
excess air level and stack losses
Residual oxygen (%)
36
Bureau of Energy Efficiency, India, 2004
© UNEP 2006
Performance Evaluation
Draft System
 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)
37
forced draft
© UNEP 2006
Training Agenda: Fuels &
Combustion
Introduction
Type of fuels
Performance evaluation
Energy efficiency opportunities
38
© UNEP 2006
Energy Efficiency Opportunities
Four main areas
 Preheating of combustion oil
 Temperature control of combustion
oil
 Preparation of solid fuels
 Combustion controls
39
© UNEP 2006
Energy Efficiency Opportunities
Preheating of Combustion Oil
 Purpose: to make furnace oil easier
to pump
 Two methods:
• Preheating the entire tank
• Preheating through an outflow heater as
the oil flows out
40
© UNEP 2006
Energy Efficiency Opportunities
Temperature Control of
Combustion Oil
 To prevent overheating
•
With reduced or stopped oil flow
•
Especially electric heaters
 Using thermostats
41
© UNEP 2006
Energy Efficiency Opportunities
Preparation of Solid Fuels
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
42
© UNEP 2006
Energy Efficiency Opportunities
Preparation of Solid Fuels
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
43
© UNEP 2006
Energy Efficiency Opportunities
Preparation of Solid Fuels
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
44
© UNEP 2006
Energy Efficiency Opportunities
Combustion Controls
• 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
45
© UNEP 2006
Training Session on Energy
Equipment

Fuels & Combustion
THANK YOU
FOR YOUR ATTENTION
46
© UNEP GERIAP
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
47
available on www.energyefficiencyasia.org
© UNEP 2006