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1 Training Session on Energy Equipment Fuels & Combustion Presentation from the Energy Efficiency Guide for Industry in Asia www.energyefficiencyasia.org UNEP 2006 Thermal Systems/Fuels Slide 2 2 UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 4 4 UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities Thermal Systems/Fuels Slide 5 5 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/Fuels Usage Used extensively in industrial applications Examples Furnace oil Light diesel oil Petrol Kerosine Ethanol LSHS (low sulphur heavy stock) Slide 6 6 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/Fuels Density Ratio of the fuels mass to its volume at 15 o C, kg/m 3 Useful for determining fuel quantity and quality Slide 7 7 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/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 oilLSHS ( Low Sulphur Heavy Stock) Specific Gravity 0.85-0.870.89-0.950.88-0.98 Table 1. Specific gravity of various fuel oils (adapted from Thermax India Ltd.) Slide 8 8 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/Fuels Viscosity Measure of fuels 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: 66 o C Slide 9 9 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/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 1 o C (kcal/kg o C) Indicates how much steam/electricity it takes to heat oil to a desired temperature Slide 10 10 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/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 Slide 11 11 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/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 Slide 12 12 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/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 ( 13 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/Fuels Storage of fuels Store in cylindrical tanks above or below the ground Recommended storage: >10 days of normal consumption Cleaning at regular intervals Slide 14 14 UNEP 2006 Type of Fuels Liquid Fuels Thermal Systems/Fuels PropertiesFuel Oils Furnace OilL.S.H.SL.D.O Density (Approx. g/cc at 150C) 0.89-0.950.88-0.980.85-0.87 Flash Point (0C)669366 Pour Point (0C)207218 G.C.V. (Kcal/kg)105001060010700 Sediment, % Wt. Max. 0.25 0.1 Sulphur Total, % Wt. Max. < 4.0< 0.5< 1.8 Water Content, % Vol. Max. 1.0 0.25 Ash % Wt. Max.0.1 0.02 Typical specifications of fuel oils (adapted from Thermax India Ltd.) Slide 15 15 UNEP 2006 Type of Fuels Solid Fuels Thermal Systems/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 Slide 16 16 UNEP 2006 Type of Fuels Solid Fuels Thermal Systems/Fuels Physical properties Heating or calorific value (GCV) Moisture content Volatile matter Ash Chemical properties Chemical constituents: carbon, hydrogen, oxygen, sulphur Slide 17 17 UNEP 2006 Type of Fuels Solid Fuels (Physical properties) Thermal Systems/Fuels Heating or calorific value The typical GVCs for various coals are: ParameterLignite (Dry Basis) Indian Coal Indonesian Coal South African Coal GCV (kCal/kg) 4,5004,0005,5006,000 Slide 18 18 UNEP 2006 Type of Fuels Solid Fuels (Physical properties) Thermal Systems/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 Slide 19 19 UNEP 2006 Type of Fuels Solid Fuels (Physical properties) Thermal Systems/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 Slide 20 20 UNEP 2006 Type of Fuels Solid Fuels (Physical properties) Thermal Systems/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 Slide 21 21 UNEP 2006 Type of Fuels Solid Fuels (Physical properties) Thermal Systems/Fuels Proximate analysis Typical proximate analysis of various coals (%) Indian Coal Indonesian Coal South African Coal Moisture5.989.438.5 Ash38.6313.9917 Volatile matter 20.7029.7923.28 Fixed Carbon34.6946.7951.22 Slide 22 22 UNEP 2006 Type of Fuels Solid Fuels (Chemical Properties) Thermal Systems/Fuels Ultimate analysis Typical ultimate analysis of coal (%) GCV (kCal/kg) 4000 5500 Slide 23 23 UNEP 2006 Type of Fuels Solid Fuels (Chemical Properties) Thermal Systems/Fuels Storage, Handling & Preparation Storage to minimize carpet loss and loss due to spontaneouscombustion Reduce carpet loss: a) a hard surface b) standard concrete/brick storage bays Coal preparation before use is important for good combustion Slide 24 24 UNEP 2006 Type of Fuels Gaseous Fuels Thermal Systems/Fuels Advantages of gaseous fuels Least amount of handling Simplest burners systems Burner systems require least maintenance Environmental benefits: lowest GHG and other emissions Slide 25 25 UNEP 2006 Type of Fuels Gaseous Fuels Thermal Systems/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 Slide 26 26 UNEP 2006 Type of Fuels Gaseous Fuels Thermal Systems/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/Nm 3 Air/Fuel ratio m 3 /m 3 Flame Temp o C Flame speed m/s Natural Gas 0.693501019540.290 Propane1.52222002519670.460 Butane1.96285003219730.870 Slide 27 27 UNEP 2006 Type of Fuels Gaseous Fuels Thermal Systems/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 Slide 28 28 UNEP 2006 Type of Fuels Gaseous Fuels Thermal Systems/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 Slide 29 29 UNEP 2006 Type of Fuels Comparing Fuels Thermal Systems/Fuels Fuel OilCoalNatural Gas Carbon8441.1174 Hydrogen122.7625 Sulphur30.41- Oxygen19.89Trace NitrogenTrace1.220.75 AshTrace38.63- WaterTrace5.98- Slide 30 30 UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels 1T) Temperature 2T) Turbulence 3T) Time Slide 33 33 UNEP 2006 Performance Evaluation Oxygen is the key to combustion Principle of Combustion Thermal Systems/Fuels Bureau of Energy Efficiency, India, 2004 Slide 34 34 UNEP 2006 Performance Evaluation Stochiometric calculation of air required Thermal Systems/Fuels 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 CO 2 and O 2 in dry flue gas by volume Slide 35 35 UNEP 2006 Performance Evaluation Measure CO2 in flue gases to estimate excess air level and stack losses Concept of Excess Air Thermal Systems/Fuels Carbon dioxide (%) Excess air (%) Source: Bureau of Energy Efficiency, India, 2004 Slide 36 36 UNEP 2006 Performance Evaluation Concept of Excess Air Thermal Systems/Fuels Residual oxygen (%) Excess air (%) Bureau of Energy Efficiency, India, 2004 Measure O2 in flue gases to estimate excess air level and stack losses Slide 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 Thermal Systems/Fuels Slide 38 38 UNEP 2006 Training Agenda: Fuels & Combustion Introduction Type of fuels Performance evaluation Energy efficiency opportunities Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Slide 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 Thermal Systems/Fuels Preparation of Solid Fuels Slide 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