ELECTRIC HUB

Corona: When an Alternating Potential Difference is applied across two conductors,whose spacing is large in comparison with the diameter,then the atmospheric air surrounding the conductors is subjected to electrostatic stresses.At low voltage there is no change in the condition of atmospheric air around the conductor.However,when the potential difference is gradually increased,a stage arrives when a faint luminous glow is violet colour appears together with a hissing noise.This phenomenon is called VISUAL CORONA and is accompanied by the production of OZONE which is readily detected because of its characteristic odour.The glow is due to the fact that the atmospheric air around the conductor becomes conducting due to electrostatic stresses. DISCHARGE OF CORONA                      If the potential difference is raised still further,the glow and the noise will increase in intensity until eventually a spark over will take pla...

Classification of fuels:- Fuels may be classified as Solid,Liquid and Gaseous and as natural or prepared.The various fuels commonly used for combustion in the Thermal Power Plants are coal,Oil and Gas.Gaseous fuel is rarely economical except when the Power Plant is located near natural gas field or Gas manufacturing industries.Oil is used only where it is plentiful and cheap.Coal is the most commonly used fuel in Thermal Power Plant.                The coals can be classified in increasing order of heat value,namely peat,lignite,sub-bituminous,bituminous,semi-bituminous,semi-anthracite,anthracite and super anthracite coals. Coal Mine                         Peat is the first stage in the process of transformation of buried vegetarian into coal.Its enthalpy of combustion is about 700 kcal/kg.Owing to high moisture content,peat is not suitable for power plants.Lignite is the ne...

Boiler:- Boiler is used in Steam Power Plants are of two types  1.Fire Tube Boiler : Use restricted to low cost,small size and low pressure about 10kg/cm^ plants  2.Water Tube Boilers : A Boiler may be a straight or bent tube,single or multi drum,horizontal or vertical or inclined tube,longitudinal or cross drum Boiler                          Research and development during last 50 years has led to large Steam Generating capacity Boilers having improved design and construction.Today Boilers are more efficient,compact and lighter in weight in comparison to Old time Boilers.                    Boilers can burn low grade fuels.Super critical pressure Boilers with pressure as high as 350 Atm,temperature 600 degree centigrade and capacity 1,00,000 kg/hr are available now.

Operation of Steam Power Plant Based on a clear Schematic: Steam Power Plant basically operates on the Rankine cycle. Schematic Arrangement of Steam Power Plant Coal is burnt in a Boiler,which converts water into steam. The Steam is expanded in a Turbine,which produces Mechanical Power driving the Generator coupled to the Turbine. The steam after expansion in Prime mover is usually condensed in a Condenser to be fed into the Boiler again. In practise,however,a large number of modifications and improvements have been made so as to effect economy and improve the Thermal Efficiency of the plant. The working of a modern Coal-fired Steam Power Plant ca be studied conveniently with the help of various Cycles. Main Constituents of a Steam Power Plant are.         1.Boiler.         2.Boiler Furnace         3.Super heater and Re heater.         4.Economiser and Air Preheater.     ...

Steam Power Plant: A Steam Power Plant is also known as a Thermal Power Plant.This provides the major share of Electrical Energy in India as well as in other Countries.In Steam Power Plants,the heat of combustion of fossil fuels such as Coal,Oil and Gas is utilised by the Boilers to raise Steam at High Pressure and Temperature. Steam Power Plant                  The Steam so produced is used in driving the Steam Turbine or sometimes steam Engine coupled to Generators and thus in Generating Electrical Energy.              Essential features of such power plants are Boilers, Turbines coupled to electrical generators,condensers and large number of auxiliaries.              The Thermal Efficiency of Steam Power Plant is quite low that is about 30% and Overall Efficiency is about 29% .In steam power plants more than 50% of total heat of combustion is lost as heat...