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Chem iv unit_2_st_[compatibility_mode]


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Chem iv unit_2_st_[compatibility_mode]

  1. 1. Unit 2 Content 2.1 CoalsFossil fuels and petroleum products - Formation of coals - Uses of coals 2.2 Petroleum (crude oil) - Formation of petroleum - Petroleum refinery - Petrochemical Products Chemistry IV: SCI 32222 Content Energy Consumption2.3 Polymers • Per capita energy consumption - Polymerization reactions - Structures of polymers - Synthetic and natural polymers2.4 Pollutions produced by petrochemical industry and uses Energy Consumption Energy ConsumptionEnergy consumption in the US Energy consumption in the US 1
  2. 2. Energy consumption in Thailand Energy ConsumptionEnergy consumption in the US TOE = Thousand tons of Oil Equivalent; 1 TOE = 10,000 kcal•Energy consumption in Transportation •Energy consumption in Industry•Energy consumption in Residential Energy from Fossil Fuels • The combustion of fossil fuels – coal, natural gas, and petroleum – provided nearly 85% of all the energy used in the world. 2
  3. 3. Energy from Fossil Fuels Energy from Fossil Fuels • Every time we use an • Fossil fuels are non- electrical device, energy renewable energy flows from a power resource. It is not station to the device you unlimited. are using. • Once they have been • Most of our electricity burned we cannot comes from the burning replace them. of the fossil fuels. Fossil Fuels Fossil fuel energy resources include • Petroleum • These are all – Oil (liquid) hydrocarbons, – Natural gas (gas!) consisting of mainly – Oil (Tar) sands (solid) carbon and hydrogen – Oil shale (solid) • The hydrocarbons form • Coal from buried organic matter• World commercial energy sources for electrical power: 2.1 Coals 3
  4. 4. What is Coal? Coal• Coal is our most abundant fossil fuel resource. • Coal forms from organic plant material on land• It is a complex mixture of organic chemical substances containing carbon, hydrogen and • Plant material accumulates in swamps in a tropical oxygen in chemical combination, together with or semi-tropical environment smaller amounts of nitrogen and sulfur.• This organic part of coal has associated with it • Again, the organic material is buried progressively, various amounts of moisture and minerals. leading to increases in temperature and pressure Formation of coals • Swampy environments on land • Land plants appeared about 400 million years ago • Anaerobic conditions • Burial • Heat and pressure Formation of coals• So, the conversion is: – plant material => peat => coal – matter is compressed, water is squeezed out, and density increases• Coal mainly found between layers of sandstone and shale 4
  5. 5. Types of Coal Types of Coal: Lignite (lowest quality) Sub-bituminous coal Bituminous coal Anthracite (highest quality) Types of Coal Types of Coal • Lignite coal, or brown coal, is a very soft coal that contains up to 70% water by weight. • Lignite (volatile-rich) • Sub-bituminous coal contains less carbon and more water, and is therefore a less efficient sourceIncreasing grade • Sub-bituminous of heat.due to highertemperatures and • Bituminous • Bituminous coal, or soft coal, contains betweenpressures 69% and 86% carbon by weight and is the most • Anthracite abundant form of coal. • Anthracite coal is a dense, hard rock with a jet- • Graphite black color and a metallic luster. (metamorphosed, no volatile substances, so will not burn)In general, lower grades of coal have more volatile, orgaseous, components Organisation for Economic Co-operation and Development (OECD) 5
  6. 6. Uses of coalsAbout 90% of coal production is burned to produce • Coal is burning in a boiler to heat water to produce electricity. steam. • The steam, at tremendous pressure, flows into a - Coal that is going to be burned in solid form may go turbine, which spins a generator to produce through a variety of preparation processes. electricity. - The simplest of these is removing foreign material and • The steam is cooled, condensed back into water, screening for size. Large pieces may be crushed, or the and returned to the boiler to start the process over. whole mass pulverized to a certain size. Uses of coalsInside the power station Inside the power station Energy flow diagram Chemical Thermal Kinetic energy energy in coal energy in turbine Electrical Kinetic energy energy in generator Coal MiningTwo basic types of Coal Mining: 1) Subsurface (underground) 2) Surface 6
  7. 7. Mining coal Mining coal 1) Subsurface (underground) 2) Surface • Shaft mining • Strip mining – Tunneling into hillsides – extract mineral deposits – Dangers to miners that are close to the surface. – Significant landscape changes Wyoming strip mine Abandoned mine shafts in Marl, Germany Environmental impacts of coal • Mining pollution – Tailings – Run-off • Air and water pollution – Acid rain Coal rail cars in Ashtabula, Ohio. Environmental impacts of coal Environmental impacts of coal Environmental Impacts of Burning Coal:Environmental Impacts of the Mining Process: - Increases CO2 concentration in atmosphere Prior to 1977, most surface mines were - Lower quality coals release sulfur causing abandoned. “Acid rain”. Leading to water pollution and acid mine drainage. Sulphur is released as sulphur dioxide, SO2, when Current law requires all surface mines to be Coal is burnt. reclaimed. S + O2 ----> SO2 S + 3O2 ----> 2SO3 7
  8. 8. Environmental impacts of coal• Acid rain can be avoided in two ways.• Removing the sulphur from the fuel• Removing SO2 from the power station’s waste gases.• Both these options are expensive and add considerably to the cost of producing electricity. 8