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- 1. 1 Training Session on Energy Equipment Fuels & Combustion Presentation from the “Energy Efficiency Guide for Industry in Asia” www.energyefficiencyasia.org © UNEP 2006
- 2. 2 © UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities
- 3. 3 © UNEP 2006 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
- 4. 4 © UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities
- 5. 5 © 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)
- 6. 6 © 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
- 7. 7 © 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 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.)
- 8. 8 © 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
- 9. 9 © 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
- 10. 10 © 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 Gross Calorific Value (kCal/kg) Kerosene 11,100 Diesel Oil 10,800 L.D.O 10,700 Furnace Oil 10,500 LSHS 10,600
- 11. 11 © 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
- 12. 12 © 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
- 13. 13 © 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
- 14. 14 © UNEP 2006 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.)
- 15. 15 © 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
- 16. 16 © 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
- 17. 17 © UNEP 2006 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
- 18. 18 © 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
- 19. 19 © 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
- 20. 20 © 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
- 21. 21 © 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
- 22. 22 © UNEP 2006 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
- 23. 23 © 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
- 24. 24 © 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
- 25. 25 © 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
- 26. 26 © 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
- 27. 27 © 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
- 28. 28 © UNEP 2006 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
- 29. 29 © 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 -
- 30. 30 © UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities
- 31. 31 © UNEP 2006 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
- 32. 32 © UNEP 2006 Performance Evaluation • 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
- 33. 33 © UNEP 2006 Performance Evaluation Oxygen is the key to combustion Principle of Combustion Bureau of Energy Efficiency, India, 2004
- 34. 34 © 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
- 35. 35 © UNEP 2006 Performance Evaluation • 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
- 36. 36 © UNEP 2006 Performance Evaluation 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
- 37. 37 © UNEP 2006 Performance Evaluation 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
- 38. 38 © UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities
- 39. 39 © UNEP 2006 Energy Efficiency Opportunities Preheating of combustion oil Temperature control of combustion oil Preparation of solid fuels Combustion controls Four main areas
- 40. 40 © UNEP 2006 Energy Efficiency Opportunities 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
- 41. 41 © UNEP 2006 Energy Efficiency Opportunities To prevent overheating • With reduced or stopped oil flow • Especially electric heaters Using thermostats Temperature Control of Combustion Oil
- 42. 42 © UNEP 2006 Energy Efficiency Opportunities 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
- 43. 43 © UNEP 2006 Energy Efficiency Opportunities 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 Preparation of Solid Fuels
- 44. 44 © UNEP 2006 Energy Efficiency Opportunities 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 Preparation of Solid Fuels
- 45. 45 © UNEP 2006 Energy Efficiency Opportunities • 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
- 46. 46 Training Session on Energy Equipment Fuels & Combustion THANK YOU FOR YOUR ATTENTION © UNEP GERIAP
- 47. 47 © 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