Aluminum is derived from the naturally occurring ore called Bauxite. Bauxite is refined into alumina which is electrochemically reduced into aluminum in reduction cells or pots (Hall-Herault process). The molten aluminum is then either cast into ingots, bars, rolled into sheets, plates or foil, or drawn into rod. These intermediate shapes are then shipped to processing plants which shape the aluminum into consumer products. Click on a process step below for more information.
Saturday, 27 August 2011
Electricity GenerationEighty-two percent of Kentucky's coal is used to generate electricity. After coal is mined, it is transported to power plants by trains, barges, and trucks. A conveyor belt carries the coal to a pulverizer, where it is ground to the fineness of talcum powder. The powdered coal is then blown into a combustion chamber of a boiler, where it is burned at around 1,400ºC. Surrounding the walls of the boiler room are pipes filled with water. Because of the intense heat, the water vaporizes into superheated high-pressure steam. The steam passes through a turbine (which is similar to a large propeller) connected to a generator. The incoming steam causes the turbine to rotate at high speeds, creating a magnetic field inside wound wire coils in the generator. This pushes an electric current through the wire coils out of the power plant through transmission lines. After the steam passes through the turbine chamber, it is cooled down in cooling towers and it again becomes part of the water/steam cycle.
Coal-Fired Power Plant
Coal-fired units produce electricity by burning coal in a boiler to heat water to produce steam. The steam, at tremendous pressure, flows into a turbine, which spins a generator to produce electricity. The steam is cooled, condensed back into water, and returned to the boiler to start the process over.
For example, the coal-fired boilers at TVA’s Kingston Fossil Plant near Knoxville, Tennessee, heat water to about 1,000 degrees Fahrenheit (540 degrees Celsius) to create steam. The steam is piped to the turbines at pressures of more than 1,800 pounds per square inch (130 kilograms per square centimeter). The turbines are connected to the generators and spin them at 3600 revolutions per minute to make alternating current electricity at 20,000 volts. River water is pumped through tubes in a condenser to cool and condense the steam coming out of the turbines.
The Kingston plant generates about 10 billion kilowatt-hours a year, or enough electricity to supply 700,000 homes. To meet this demand, Kingston burns about 14,000 tons of coal a day, an amount that would fill 140 railroad cars.
Friday, 5 August 2011
Wednesday, 3 August 2011
In today’s world, it is private companies rather than government that pay for and carry out most scientific research. Do you think the advantages outweigh the disadvantages?
Rephrasing the question
Emergence of free market economies has initiated (encouraged) private companies invest huge amounts of money in scientific research, so as to enable them to use the findings, for profitable business activities. The increasing domination of private enterprises, especially multinational corporations in carrying out most research projects has downplayed the role of the government and raised certain issues.
1. Huge investments are required for scientific research and so government can concentrate on more priority issues like health care and social security.
2. Better quality research and better utilisation of money for research in it is carried out by private companies.
3. This would expedite (speed up) the development of the economy through technological innovations.
4. This would enable government to invest in essential research concerning the basic needs of the society.
1. Monopolisation of certain research and consequently the products from inventions may be priced very high. (eg: medicines)
2. Profit motive and therefore no social commitment. May not be accessible to the poor.
3. Sometimes research may be hampered as private companies may not be able to invest as much as government as it may not be financially feasible (alternative sources of energy).
Since the resources of the government is greatly limited, there is no harm in allowing private companies to carry out majority of scientific research. Hence, government can concentrate more on essential research concerning the basic needs of the people, where private companies may not be interested in participating.
· Research and development
· Carry out research
· Research into
· Research on
· State funding
· Corporate research
· Corporate companies
· Monopolistic policies
· Scientific development
· Social commitment
· Profit motive
· Money making
· Greater benefits
· private enterprises
· private sector
You have read this post. Why don't you write down your opinion it. I greatly appreciate it.