Wednesday, November 2, 2011

COAL FIRED ELECTRICITY GENERATION.

              Energy, we all need it to do a work. As humans we use energy stored in our body. But most of the time energy stored in our body is not sufficient enough to finish the required work. Therefore we use machines to do our work. Most of these machines driven by electricity which makes electricity to play a major role in the form of energy for development of a country. Electricity generation required an efficient energy source. Energy sources that we use today is limited resulting a global problem called energy crisis.s
              Hydro power is the most common energy source that people familiar with the electricity generation in Sri Lanka. Other than that developed countries use nuclear energy to generate electricity. Fossil fuels, geothermal energy is also using for electricity generation. Due to the modern climatic changes hydro power stations cannot operate at their maximum capacity. And Nuclear power plants need more advanced technology and more capital which cannot afford by developing country like Sri Lanka, which lead to find a convenient alternative energy source to generate electricity. Such convenient alternative energy source is Coal. Coal is a solid fossil fuel which containing Carbon and it is the most impure of fuels, its impurities range from trace quantities of many metals including uranium and thorium to much larger quantities of aluminum and Iron to still larger quantities of impurities of such as Sulfur. 
           In a coal power plant have some kind of rotating machinery to convert heat energy of combustion in to mechanical energy which then operate an electrical generator. This energy conversion is done by using several steps. First step of this energy conversion is burning the coal in boiler furnace to produce heat In second step include thermodynamic process which are.
  1. The heat from combustion of the coal boils water in the boiler to produce steam. In modern power plant, boilers produce steam at a high pressure and temperature. 
  2. The steam is then piped to a turbine. 
  3. The high pressure steam impinges and expands across a number of sets of blades in the turbine. 
  4. The impulse and the thrust created rotate the turbine. 
  5. The steam is then condensed and pumped back into the boiler to repeat the cycle.
           In third step rotation of the turbine rotates the generator to produce electricity based on the faradays principle of electromagnetic induction. In practice to effect these three stages of conversion, many systems and sub systems have to be in service. Also involved are different technologies, like combustion, aerodynamics, heat transfer, thermodynamics, pollution control, and logistics. Leading to much complex tasks in coal fired electricity generation.
          When a country involves in coal fired electricity generation, Country will have the benefit of generating large amount of electricity in one place. And much more advantages. Coal fired electricity generation also has disadvantages and some threats to the environment and to the people living around it. Those disadvantages and threats can be avoided using proper techniques which will discuss in my next post.