2. THE NATURALLY OCCURING OR MANUFACTURED COMBUSTIBLE SUBSTANCES WHICH ACT AS SOURCE WHEN BURNT. “THE FUEL UNDERGOES EXOTHERMIC REACTION WITH OXYGEN PRODUCING HEAT.” FUELS
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4. CLASSIFICATION OF FUELS: Depending on their physical state may be classified into Solid fuels Liquid fuels Gaseous fuels They are further divided into Primary or natural Secondary or derived fuels
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6. Characteristicoffuel: High calorific value Composition of the fuel Specific heat of combustion Flame temperature Fire point Flash point Pour point Cloud point Explosive range
7. HIGH CALORIFIC VALUE3 of solid or liquid fuel or 1*10ˆ-6 at one atmosphere pressure of a gaseous fuel is completely burnt in excess : The total quantity of heat liberated , when 1*10ˆ-of air or oxygen and the products of combustion cooled to room temperature . COMPOSITION OF FUEL: low moisture content , less volatile matter, high carbon content or combustible substance, ballast must be low. FLAME TEMPERATURE: The minimum temperature to which an object can be heated by a flame of fuel. FIRE POINT : Temperature in which the oil vapor will catch fire and continue to burn.
8. FLASH POINT: It is the minimum temperature at which a sample of a fuel oil gives off enough vapors to catch fire (but don’t continue to burn) by the naked flame or electric discharge . It depends on vapour pressure. POUR POINT: The temperature at which cloudiness appear in a sample of oil due to the separation of wax under standard condition . CLOUD POINT : The temperature at which oil ceases to flow , when cooled under standard conditions. EXPLOSIVE RANGE : The limiting composition of a gas –air mixture , beyond which the mixture will not igniteand continue to burn .
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10. They should have high carbon content high calorific value. It should give low ash content or no ash or carbon. Should possess low moisture and volatile matter. Rate of combustion should be uniform and moderate. Should have moderate ignition temperature. Combustion should be easily controllable. It should not produce toxic gases during combustion. Quality of a good fuel
11. GASEOUS FUELS The important gaseous fuels are Water gas Coal gas Producer gas Acetylene Bio gas Liquefied petroleum gas etc..
12. Advantages of gaseous fuel: Gaseous fuels have high calorific value. Rate of combustion is very high but can be easily controlled. The higher temperature is obtained and can be easily controlled. It can be easily distributed through pipes from the source of production. They neither produce smoke nor ash .
14. Natural gas It is found in nature in association with or without petroleum deposits.
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17. Used as an excellent industrial and domestic fuel. Used as raw material for the manufacture of carbon black and hydrogen gas. Employed as a member of chemicals in various synthetic processes. APPLICATION
25. PROCESS C + H2O ----------> CO +H2 H=121.5 KJ (STEAM) (WATER GAS) C(s)+O2(g)-----------> CO2(GAS) 2C (s) + O2(g) --------> 2CO
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27. APPLICATION Used as a source of hydrogen gas. As a fuel gas and as an illuminating agent. In the manufacture of methanol and synthetic petrol. As reducing agent.
28. PRODUCER GAS It is a mixture of carbon monoxide and nitrogen.
30. Calorific value The calorific value of producer Gas is 1308kcal/m3 The low calorific value is due to the presence of large excess of non combustible gases like nitrogen and carbon dioxide.
31. MANUFACTURE Cup & cone feeder Producer gas outlet Refractory fire bricks Distillation zone Reduction zone Combustion zone Ash zone
32. PROCESS C (s)+ O2(g) ----------->CO2(g) H= -394 kj CO2(g) +C (s)-------> 2CO(g) H= +163 kj The overall reaction 2C(s)+O2(g)----------->2CO(g) H= -231 kj
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34. APPLICATION It is used as a fuel for heating retorts in preparing coal gas. It is used as a fuel for heating open hearth furnace in the manufacture of steel and glass. It is used as a reducing agent in metallurgy.
39. ADVANTAGE OF BIO GAS The production of biogas is more economical. It also yields simultaneously excellent manure. The nitrogen content of the manure is about 2% as against 0.75% in farm yard manure. The biogas has all the advantages of gaseous fuel. It does not contain any poisonous gas like carbon monoxide. It can burn with pale blue flame and gives temperature of 813K with proper burner.
41. LPG LPG is a mixture of lower hydrocarbon of C3 and C4, which are mainly propane, butane, isobutylene and butylene with little or no propylene and ethane.
45. APPLICATION It is widely used as a domestic fuel for cooking. As industrial fuel. As motor fuel.
46. It has high calorific value. It burns with a smokeless flame and does not cause pollution. It does not produce any poisonous gas on combustion. It is easy to handle and convenient to store. ADVANTAGES OF LPG
47. ADVANTAGES OF LPG AS MOTOR FUEL It is less costlier than gasoline. It mixes easily with air and gives better distribution. Residue and oil contamination is small as it burns clearly. Engine life is increased.
48. DISADVANTAGE OF LPG AS MOTOR FUEL Handling has to be done with utmost care. Due to its faint odor, leakage can not be detected easily. It is advantageous only in engines working under high compression ratio. It has low octane number and road sensitivity is very high.
