Important points about fossil fuel.pdf

Petroleum
A petroleum is liquid mixture of hydrocarbons that is present in suitable rocks and can be extracted and refined to produce fuel like diesel oil, petrol and paraffin etc. Million years ago died plants and animals settled on the surface of earth and then mud layers covered them. Due to this oxygen supply cut off. There are two types of theories in regarding of origin of petroleum i-e inorganic theories an organic theories. According to inorganic theory petroleum is formed itself by chemical reactions occurred in earth. To prove inorganic behaviour different theories are present including Metal carbide theory, Volcanic theory, Earthquake theory and Serpentinization theory. Evidences for inorganic origin of petroleum are Geographical location and Stability with depth. According to organic theory of petroleum ,petroleum is a substance that form by decaying of organisms  present at several kilometers below in the earth. Due to high pressure and temperature in the absence of oxygen change mud into rock and organic matter into petroleum and natural gas finally. Evidences for organic origin of petroleum includes presence of brine with petroleum, polarized light pass through petroleum products in such a way that is same when polarized light pass through organic oils and molecules of hydrocarbon is similar to  organic matter. 
Oil Extraction and Recovery
Primary Recovery includes natural water moving oil downward into the well, expansion of natural gas at top of reservoir, expansion of gas  dissolved in the crude oil in the starting and gravity drainage causes the movement of oli from upper to lower part. Recovery factor is about 5-15%.
Secondary Recovery: Due to increase in reservoir pressure, external energy is given to inject fluids. Injection of water as well as natural gas and gas lifting increase reservoir pressure and Carbon dioxide, water and other gases are injected and fluid density is reduced. Recovery is about 35-45%.
Enhanced recovery: By heat crud oil Steam is Produced which increase mobility as well as extraction by cogeneration plant. Gas turbine is usually used to produced electricity. It is used in S.J Valley to generate heavy oil. Carbon dioxide floating is used and microbes break the hydrocarbon chain to oil.
Fuel
Fuel is a fissionable chemical that generates energy and includes combustion substances and is a source of heat. Fuel is a substance which after oxidation becomes a source of heat for practical and commercial uses.

Calorific Value
Calorific value is defined as the amount of heat released in calories by complete combustion of combustible material with Oxygen as well as condensation of products to desired temperature. Mean calorific value of any fuel containing hydrogen and carbon can be calculated by
Total calories= (% of C × 8137) + (% of H × 34500) / 100
Determination of calorific value of any liquid or solid fuel is done by burning of definite quantity in bomb calorimeter. 
Modern Concept of Fuel
Combustion is not necessary for a fuel to give energy. For example when electrical energy or Nuclear energy is used as a source of energy it is considered as a fuel. Classification of Fuel on basis or Origin is of two types i-e Natural and Artificial Fuel. In natural fuels wood, peat is solid , petroleum is liquid and natural gas is present in gaseous form. In Artificial Fuels semi cock and charcoal is solid, petrol , kerosene, fuel, gas oil, solar oil, coal tar is liquid and coke-oven gas, semi cock gas and producer gas is considered as gaseous form. Classification of Fuel on the basis of origin, is of two types. First is Primary Fuel or Primary Natural occurring fuel e.g. wood, peat, lignite, coal, anthracite, oil, shale and petroleum etc. Second is Secondary Fuel or prepared fuel derived from primary fuel. For Example motor spirit, tars and oils, lignite tar, kerosene, diesel oil, gasoline and synthetic fuels. 
Economic Importance of fuel depends upon various factors such as
• Its Geoghrafic distribution.
• Cost about its trapping and transport
• Relative calorific value
• Easy to combust
Industrial Fuel are Classified into two groups i-e power generating fuel and process fuel.
Power Generating Fuel: To obtain energy these are burnt in power plants.
Process Fuel is used to produce energy from industrial furnace and driers for purpose of used in various industrial processes. 
Criterion of Selection of Fuel
• Supply position
• Suitability to process
• Calorific Value
• Cost of Fuel

Requirements of Fuel
• Release of thermal energy of reasonably high value
• Reasonably high velocity of combustion
• Low percentage of non-combustible
• Proper ignition temperature
• Low cost
Factors Affecting quality and BTU of solid fuel
• Moisture Content
• Fixed percentage
• Percentage of volatile matter
Properties of Fuel
1)    High Calorific                    2)  Composition of Fuel         3)  Specific heat of combustion               4)    Ignition temperature      5)  Flame Temperature          6)  Explosive Range
7)    Flash Point                        8)  Fire Point                             9) Aniline Point
10)  knocking                          11)  Specific Gravity                12) Pour point
13) Cloud point                      14) Coke Number                    15) Viscosity
Solid Fuel
It is combustible organic material and have incombustible part called ballast. The Organic Part usually consists of C, H and S. Natural Solid Fuel contains Wood, peat, Lignite and coal. Artificial Solid Fuel contains charcoal, coke and Briquettes. Properties of Coal contains color, texture, hardness, friability, specific gravity and calorific value etc. Classification of Coal: It has four types i-e banded coal, splint coal, Bog head coal and cannel coal. By grinding fossil coal we get Pulverised Coal. Advantages of Solid Fuel over liquid and gas is that it is easy to store due to its high ignition temperature and cheapness. Disadvantages of Solid Fuel over liquid and gas is that a large amount of unburnt material also wasted with clinker. Analysis of coal consists of three types i-e Proximate analysis, ultimate analysis and calorific value. Chemical processing of Solid Fuel based on heterogeneous, non-catalytic process in solid-gas and multiphase systems are carried out at high temperature. Methods of High Temperature processing includes pyrolysis, hydrogenation and Gasification. High Temperature Carbonisation yield 75% coke and 15 lbs per ton light oil. On other hand Low temperature Carbonisation yield 75-80% coke and 20 lbs per ton light oil.
Types of Coking includes beehive coking and coproduct coking. With the help of destructive distillation chemicals were get initially by coal. The Direct coke oven gas is basically a mixture of vaporous and gaseous substances. The light oil is a complex mixture having low boiling hydrocarbons and 1.6-3.4% CS2. In refractory lined furnace a gas is produced.

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