Fuels and combustion

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1 A PRESENTATION ON: FUels & Combustion SUBMITTED TO: Prof. VASANTHAKUMAR PAI SIR Dept.of INDUSTRIAL CHEMISTRY KUVEMPU UNIVERSITY, SUBMITTED BY: ASHA.E 3 rd SEMESTER, INDUSTRIAL CHEMISTRY KUVEMPU UNIVERSITY

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2 Introduction Type of fuels Combustion Conclusion Fuels and Combustion

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3 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 Fuels and combustion

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CHEMICAL FUELS SECONDARY OR DERIVED FUELS PRIMARY OR NATURAL FUELS SOLID: Wood,coal , lignite LIQUID: Crude oil GASEOUS: Natural gas SOLID: coke,charcaol,petroleum GASEOUS:coal gas, water gas, biogas LIQUID: Petrol,kerosene,diesel . CLASIFICATION OF FUELS

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5 Calorific value Calorific value is the total quantity of heat liberated when a unit mass of fuel burn completely. Measured at 25˚C. Heat or energy produced Gross calorific value (GCV): vapour is fully condensed Net calorific value (NCV): water is not fully condensed. NCV = GCV – (mass %hydrogen)(9)( λ v )kJ/kg λ v –latent heat of water vapour at reference temperature, normally at 298.15K. λ v at 298.15K = 2442.5kJ/kg. Introduction Fuels and combustion

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6 Units of calorific values: For solid and liquid calorific value are Joules/kg [ in SI system] calori / gram [ in cgs system] kcalori/kg [ in mks system] B.T.U/lB [ British system ] Relation 1kcal/kg = 1.8B.T.U/lB. For gases; kcal/cubic meter. BTU/cubic feet. Relation 1kcal/cubic meter = 0.107BTU/IB. Introduction Fuels and combustion

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7 Introduction Type of fuels Combustion Conclusion Fuels and combustion

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8 Type of Fuels Liquid Fuels Fuels and combustion Usage Used extensively in industrial applications Examples Furnace oil Light diesel oil Petrol Kerosine Ethanol LSHS (low sulphur heavy stock)

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9 Type of Fuels Liquid Fuels Fuels and combustion Density Ratio of the fuel’s mass to its volume at 15 o C, kg/m 3 Useful for determining fuel quantity and quality

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10 Type of Fuels Liquid Fuels Fuels and combustion Specific gravity Ratio of weight of oil volume to weight of same water volume at a given temperature Specific gravity of water is 1 at 4˚C. 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

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Type of Fuels Liquid Fuels Fuels and combustion 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: 66 o C

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12 Type of Fuels Liquid Fuels Fuels and combustion 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

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13 Type of Fuels Liquid Fuels Fuels and combustion 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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14 Type of Fuels Liquid Fuels Fuels and combustion 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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15 Type of Fuels Liquid Fuels Fuels and combustion 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 Calorific value: Typical GCVs of some of the commonly used liquid fuels are given below:

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16 Type of Fuels Liquid Fuels Fuels and combustion 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

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17 Type of Fuels Liquid Fuels Fuels and combustion 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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18 coal DEFINITION Coal is a highly homogeneous matter. Coal is the most important fossil fuel. In india, most of the calories are situated in madhya pradesh,West Bengal, Bihar and the bangs of river Godavari. Fuels and combustion Type of Fuels Solid Fuels

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19 Type of Fuels Solid Fuels Fuels and combustion Coal classification Anthracite: hard and geologically the oldest Bituminous L ignite: soft coal and the youngest Further classification: semi- anthracite, semi-bituminous, and sub-bituminous

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20 Type of Fuels Solid Fuels Fuels and combustion Physical properties Heating or calorific value (GCV) Moisture content Volatile matter Ash Chemical properties Chemical constituents: carbon, hydrogen, oxygen, sulphur

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21 Type of Fuels Solid Fuels (Physical properties) Fuels and combustion 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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22 Type of Fuels Solid Fuels (Physical properties) Fuels and combustion 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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23 Type of Fuels Solid Fuels (Physical properties) Fuels and combustion 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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24 Type of Fuels Solid Fuels (Physical properties) Fuels and combustion 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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25 Type of Fuels Solid Fuels (Physical properties) Fuels and combustion 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

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26 Type of Fuels Solid Fuels (Chemical Properties) Fuels and combustion Ultimate analysis Typical ultimate analysis of coal (%) GCV (kCal/kg) 4000 5500

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27 Type of Fuels Solid Fuels (Chemical Properties) Fuels and combustion 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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28 Type of Fuels Gaseous Fuels Fuels and combustion 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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29 Type of Fuels Gaseous Fuels Fuels and combustion 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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30 Type of Fuels Gaseous Fuels Fuels and combustion 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 0.6 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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31 Type of Fuels Gaseous Fuels Fuels and combustion Liquefied Petroleum Gas (LPG) Propane, butane and unsaturates, lighter C 2 and heavier C 5 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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32 Type of Fuels Gaseous Fuels Fuels and combustion 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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33 Type of Fuels Comparing Fuels Fuels and combustion 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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34 Introduction Type of fuels Combustion Conclusion Fuels and combustion

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35 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) CO 2 (b) CO resulting in less heat production Principles of Combustion Fuels and combustion

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36 Combustion 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 Fuels and combustion 1T) Temperature 2T) Turbulence 3T) Time

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37 Combustion Oxygen is the key to combustion Principle of Combustion Fuels and combustion

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38 Combustion Stochiometric calculation of air required Fuels and combustion Stochiometric air needed for combustion of furnace oil Theoretical CO 2 content in the flue gases Actual CO 2 content and % excess air Constituents of flue gas with excess air Theoretical CO 2 and O 2 in dry flue gas by volume

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39 Combustion Measure CO 2 in flue gases to estimate excess air level and stack losses Concept of Excess Air Fuels and combustion Carbon dioxide (%) Excess air (%)

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40 Combustion Concept of Excess Air Fuels and combustion Residual oxygen (%) Excess air (%) Measure O 2 in flue gases to estimate excess air level and stack losses

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41 Fuels and combustion Introduction Type of fuels Combustion Conclusion

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42 CONCLUSION FUELS: A combustible substance, containing carbon as main constituent which on proper burning, it gives amount of heat which can be used for domestic and industrial purposes. example: wood,cal,etc., COMBUSTION: Combustion is an unit processin which oxidation reaction takes place. The union of carbon,hydrogen, and sulphur with oxygen. During combustion of a fuel, the atoms of carbon , hydrogen,etc., combine with the oxygen and liberates heat at a rapid rate. Fuels and combustion

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43 Fuels & Combustion THANK YOU FOR YOUR ATTENTION QUESTIONS??????