Electric Power Generation

Electric Power Generation

1. ENERGY CONVERSION 2. INPUT ENERGY SOURCES 3. COMBUSTION 4. HEAT AND TEMPERATURE 5. COMBUSTION OF FOSSIL FUELS 6. GASIFICATION OF COAL 7. FUEL OIL 8. NATURAL GAS 9. OTHER FUELS 10. COMPARISON OF FUELS 11. DISTRIBUTED GENERATION 12. THE FUEL CELL 13. NUCLEAR FUEL - NUCLEAR

fuel

fire

Boiler/ furnace

steam

Engine turbine

Shaft generator turbine

Schematic Diagram of Energy Conversion

consumer

source

1. ENERGY CONVERSION

Except for the source of heat they use to create steam, nuclear and fossil power plants are basically the same.

2. INPUT ENERGY SOURCES

———————————————————————————————— 2.1 Hydro - Depends on availability, volume and head (distance from the intake to the water wheels). 2.2 Fossil Fuels - Typical Characteristics (Approximate Values) Components in Percent Fuel Btu/lb Carbon Hydrogen Oxygen Sulphur Nitrogen Ash ———————————————————————————————— Wood 9,000 52.0 6.0 25.0 0.3 15.0 1.7 Coal Lignite 11,000 60.0 6.0 4.0 1.0 1.0 28.0 Oil 18,500 88.0 8.2 0.5 3.0 0.1 0.2 Natural Gas 22,000 69.0 23.5 1.5 0.3 5.7 0.0

2.3. Nuclear Fuels Fuel Btu/lb Uranium Plutonium 38.7 billion Thorium 2.4 Other Fuels Fuel Tar Garbage vary widely, but the Manure Heap Gas contents generally include Aquatic & Land Plants hydrogen as basic elements. Biogases Husks

Components may combustible carbon and

2.5 Other Energy Sources Geo-thermal Wind Tides Solar (Direct Sun Rays) Temperature Differences between Surface & Deep Layers of Water Bodies

Variable - from very large quantities to very small quantities - Some not always available.

3. COMBUSTION

Elements, Molecules and Atoms

Illustrating Composition of Atoms & Molecules

Atomic and Molecular Weights

• • • • • • •

Hydrogen (H) .............. 1 Carbon (C) ................. 12 Nitrogen (N) .............. 14 Oxygen (O) ................ 16 Sulphur (S) ................. 32 1 x 12 + 2 x 16 = 12 + 32 = 44 that is, the molecular weight of carbon dioxide ( CO2) is 44.

Chemical Reactions—Combustion Equations

The principal chemical reactions of the combustion of fossil fuels are • shown in the following equations expressed in symbols: (1) Carbon to carbon monoxide 2C + O2 = 2CO • (2) Carbon to carbon dioxide, 2C + 2O2 = 2CO2 • (3) Carbon monoxide to carbon dioxide 2CO + O2 = 2CO2 • (4) Hydrogen to water 2H2 + O2 = 2H2O • (5) Sulphur to sulphur dioxide S + O2 = SO2

•

4.HEAT AND TEMPERATURE

Comparison of F & C Temperature Scales

Temperature of Combustion

Ignition Temperatures

5.COMBUSTION OF FOSSIL FUELS Classification of Coals

Ultimate Analysis of Coal Sample

Example, if the coal contained 5% moisture, the heating value would be 14,614 x 0.95 or 13883 Btu.

6. GASIFICATION OF COAL

Variations of Gasification Process (Courtesy Power Engineering)

Comparison of Syngas and Coal Components (% volume)

7. FUEL OIL

specifications • Specific Gravity .......................5 to 14 degrees API • Viscosity ...................................300 seconds Saybolt at 122ฐF • Btu .............................................Approx. 18,500 Btu per pound • Water Content .........................Not more than 2.0 percent • Sediment Content ...................Not more than 0.25 percent

8. NATURAL GAS

Natural gas almost always accompanies petroleum and is released when the pressure on the oil is released. The gas consists mainly of light hydrocarbons such as methane (CH4), ethane (C2H6), propane (C3H8)j butane (C4H10), and others, all of which are volatile.

9.OTHER FUELS

• Vegetation, both land and aquatic; e.g. • • •

bagasse from sugar cane,corn husks, etc. Tars as residue from coal and coke operations; e.g. from manufactured gas, steel making, etc. Garbage from industrial, commercial and residential waste, etc. Gases from garbage piles and manure heaps, etc.

10.COMPARISON OF FUELS

The decision as to what fuel should be burned depends on the individual plant, the equipment and op erating personnel, local conditions,and principally on the price of the fuel. The price, in turn, may be affected b y its availability, transportation and handling costs.

11.DISTRIBUTED GENERATION

As the name implies, generating units of relatively small dimensions and capacity (from 5 kW to 5 MW) are installed at or near the load to be served and usually connected to the associated distribution or transmission system. These units can serve: 1. to supply base load 2. for peak shaving 3. to supply additional load instead of revamping of existing supply facilities 4. as independent producers of electricity in areas remote from system sources, or where it may be mor e economic to do so

12. THE FUEL CELL

THE FUEL CELL • 1. • 2. • 3. • 4. • 5.

Proton Exchange Membrane Alkaline Fuel Cell Phosphoric Fuel Cell Molten Carbonate Fuel Cell Solid Oxide Fuel Cell

13. NUCLEAR FUEL - NUCLEAR REDUCTION Uranium Isotopes

The Atom: Structure and Parts

Nuclear Fission

In chain reaction, neutrons emitted by fissioning U-235 can fission other U-235 atoms. When a U-238 atom captures a neutron, it most often transmutes to plutonium after several days. Fissioning atoms raise the temperature of the mass of which the

Neutrons thrown out by fission fragments may (1) convert fertile U-238 to fissionable Pu-239, (2) fission U -235 nuclei, or (3) be captured by nonfissionable or nonfertile material s, or (4) escape from