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22.1 Fossil fuels

22.1 Fossil fuels. 22.1.1 Introduction to fossil fuels Our society uses a lot of energy. An important way to get energy is by burning fuels. Fuels can be solids, liquids or gases. Coke - a solid fuel. 22.1 Fossil fuels. 22.1.1 Introduction to fossil fuels.

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22.1 Fossil fuels

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  1. 22.1 Fossil fuels • 22.1.1 Introduction to fossil fuels • Our society uses a lot of energy. • An important way to get energy is by burning fuels. Fuels can be solids, liquids or gases. Coke - a solid fuel

  2. 22.1 Fossil fuels • 22.1.1 Introduction to fossil fuels Liquefied petroleum gas (LPG) - a common gaseous fuel Petrol - a liquid fuel for car

  3. 22.1 Fossil fuels • 22.1.1 Introduction to fossil fuels • Most of the world’s energy is obtained by the burning of fossil fuels. • The major fossil fuels are coal, petroleum and natural gas.

  4. 22.1 Fossil fuels • 22.1.2 How was coal formed? • Millions of years ago, swamp forests covered large parts of the earth’s surface. • The plants died and formed thick layers of dead plant materials. Rivers washed down sand and mud to cover the dead plant materials.

  5. 22.1 Fossil fuels • 22.1.2 How was coal formed? • In time, the combined effect of heat, pressure and bacterial action gradually changed the dead plant materials into coal.

  6. 22.1 Fossil fuels • 22.1.3 How was petroleum formed? • Petroleum was formed from plants and small marine animals that lived millions of years ago. When they died, their bodies sank to the bottom of the sea and were covered by thick layers of sand and mud. • The combined effect of heat, pressure and bacterial action gradually changed the dead remains of plants and animals into petroleum and natural gas.

  7. S E A S E A m u d a n d s a n d 22.1 Fossil fuels • 22.1.3 How was petroleum formed? • Petroleum and natural gas move through porous rocks underground, until they get trapped by non-porous rocks above them. natural gas petroleum water non-porous rock sea bed porous rock Plant and marine animals died Dead plants and animals covered by sand and mud Pressure, heat and bacterial action gradually changed the dead remains of plants and animals into petroleum and natural gas

  8. 22.2 How are fossil fuels used up? • Much of the energy used in industry, households, transport and commerce does not come directly from fossil fuels. It comes from electricity.

  9. number of years 22.2 How are fossil fuels used up? • An estimate of how long the resources of fossil fuels may last.

  10. 22.3 Fractional distillation of petroleum • Petroleum is a mixture of many different compounds with different properties. Nearly all the compounds in petroleum are hydrocarbons. • To make petroleum useful, we need to sort these compounds into groups with similar properties. Petroleum can be separated into different groups by a technique called fractional distillation.

  11. 22.3 Fractional distillation of petroleum • Fractional distillation separates the petroleum into different groups of simpler mixtures. Each group of mixtures, or fraction, has a different boiling point range.

  12. 22.3 Fractional distillation of petroleum • Properties of fractions obtained from fractional distillation of petroleum in the laboratory.

  13. 22.4 Petroleum refining • 22.4.1 The refining process • In practice, fractional distillation of petroleum is carried out in an oil refinery. • In an oil refinery, there are tall towers called fractionating towers.

  14. 22.4 Petroleum refining • 22.4.1 The refining process • Petroleum is first heated to about 400 ºC in a furnace. Petroleum is turned into a mixture of liquid and vapour. • The mixture is then pumped into a fractionating tower. The top levels of the tower are cooler than the bottom levels. • The liquid portion separates out and flows to the bottom of the tower. The vapour portion rises up the tower.

  15. 22.4 Petroleum refining • 22.4.1 The refining process • Different fractions condense at different levels of the tower. • Fractions with higher boiling point ranges are condensed at lower, hotter levels of the tower. Fractions with lower boiling point ranges are condensed at higher, cooler levels of the tower. • Different fractions contain different hydrocarbons.

  16. 22.4 Petroleum refining • 22.4.2 Characteristics of fractions containing hydrocarbons with a smaller number of carbon atoms in their molecules • Lower boiling point ranges • Lighter in colour • Less viscous • Easier to evaporate • Easier to burn • Burn with clear flames

  17. 22.4 Petroleum refining • 22.4.3 Characteristics of fractions containing hydrocarbons with a greater number of carbon atoms in their molecules • Higher boiling point ranges • Darker in colour • More viscous • More difficult to evaporate • More difficult to burn • Burn with sootier flames

  18. F r a c t i o n B o i l i n g p o i n t N u m b e r o f c a r b o n (C ) r a n g e a t o m s i n e a c h m o l e c u l e o f h y d r o c a r b o n s i n e a c h f r a c t i o n < 4 0 1 – 4 p e t r o l 4 0 – 1 7 0 5 – 1 0 n a p h t h a kerosene 1 7 0 – 2 5 0 1 0 – 1 4 g a s o i l 2 5 0 – 3 5 0 1 4 – 2 5 fuel oil > 3 5 0 a b o v e 2 5 p e t r o l e u m l u b r i c a t i n g o i l s a n d w a x e s f u r n a c e bitumen 22.4 Petroleum refining Uses refinery gases as gaseous fuel as fuel for cars fractionating tower manufacturing town gas as fuel for aircraft as diesel fuel 400 C as fuel for ships as lubricating oil for machines; making candles surfacing roads and roofs

  19. 22.5 Uses of petroleum • Petroleum is used as a fuel for generating electricity, as a fuel for cars, and as a raw material in the petro-chemical industry. Making fuels for cars and lorries

  20. 22.5 Uses of petroleum Making gaseous fuel Making town gas

  21. 22.5 Uses of petroleum Making plastic goods Generating electricity

  22. 22.5 Uses of petroleum Making detergents Making alcohol

  23. 22.5 Uses of petroleum Making pesticides

  24. 22.6 Useful web links • Fossil fuels http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761586407 • Petroleumhttp://www.fwkc.com/encyclopedia/low/articles/p/p019001047f.html • Fractional distillation of petroleumhttp://homepages.enterprise.net/bobchap/science/fractionation.html • Significance of oil in modern times, origin of crude oil, world distribution of oil, status of the world oil supply http://www.britannica.com/bcom/eb/article/3/0,5716,119353+1,00.html

  25. 22.6 Useful web links • China Light and Power http://www.chinalightandpower.com.hk/n_clp/index.html • Shell Hong Kong Limited http://www.shell.com.hk/ • Hongkong Electric Group http://www.hec.com.hk/ • Hong Kong fact sheet on water, power and gas supplies http://www.info.gov.hk/hkfacts/facts_e.htm

  26. 22.6 Useful web links • Petrochemicals http://www.britannica.com/bcom/eb/article/3/0,5716,119903+10+110685,00.html

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