18-01-2012, 11:27 AM
INDUSTRIAL TRAINING REPORT
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COAL HANDLING PLANT
Coal Handling Plant is one the major sections of plant.It accounts to the major expenses incurred in generation of electricity.It involves unloading, pulverizing, storing and feeding of coal to furnace.The plant requires about 10,000-12,000 tonnes of coal per day which is supplied by COAL INDIA LIMITED.The coal is basically obtained from the JHARKHAND mines.The coal used is of SUB-BITUMINOUS type.The functions of a coal handling plant are as follows:
MAJOR COMPONENTS OF CHP
1.WAGON TIPPLER-It performs the function of unloading.Wagons of rake come to tippler and are emptied here.The process is performed by a slip-ring induction motor of rating: 55KW,415V,1480RPM.This motor turns the motor by 135 degrees and coal falls on the conveyor belts through hopper.
2.CONVEYOR-There are 14 conveyors in the plant.They are numbered so that their function can be easily demarcated.Motors employed for conveyors has a capacity of 150HP.They have a capacity of carrying coal at a rate of 400 tons per hour.The conveyors are 1m wide,3cm thick and made of chemically treated vulcanized rubber and it moves with a speed of 250-300m/min.
3.ZERO SPEED SWITCH:It is a safety device for motors.If the belt is not moving and the motor is on then the motor may burn,in such situations it checks the speed of the switch and turns of the motor if the speed is zero.
4.METAL SEPRATORS:As the belt takes coal to crusher ,no metal pieces should go along with coal.When coal is dropped to crusher hoots,the seprator drop metal pieces ahead of coal.It has a magnet and a belt,as the belt moves the metal pieces are thrown away.
COOLING TOWERS
They are evaporative coolers used for cooling water or other working medium.The tower vary in size from small roof top to 200mts tall and 100mts in dia.It can be rectangular or hyperboloid in structure.The absorbed heat is rejected to the atmosphere by the evaporation of some cooling water in FD or ID towers.Smaller towers are factory built while larger ones are made on site.They are also used in chemical plants,oil refineries etc.
THREE PHASE TRANSMISSION LINE
Three phase electric power is a common method of electric power transmission .A three phase system uses less conductor material to transmit electric power than equivalent single phase ,two phase ,or DC system at same voltage. In a three phase system three circuits reach their instantaneous peak values at different times. This delay between phases has the effect of giving constant power transfer over each cycle of current .
SUPERHEATER
A superheater is a device in a steam engine that heats the steam generated by the boiler again increasing its thermal energy and decreasing the likelihood that it will condensate inside the engine.They increase the efficiency of steam engine.Steam which is not superheated is called saturated or wet steam.
ECONOMIZER
They are mechanical devices intended to reduce energy consumption or to perform another useful function like preheating a fluid.In boilers, economizer are heat exchange devicesthat heat fluids usually water,upto but not beyond the boiling point of fluid.They make use of enthalpy and improve boiler’s efficiency.They are a device fitted to a boiler which saves energy by using the exhaust gases from the boiler to preheat the cold water used to fill it.Economizer lowers stack temperatures which may cause condensation of acidic combustion gases and serious equipment corrosion damage,if care is not taken in their design and material selection .
HIGH TENSION SWITCHGEAR
In high tension switchgear I was told about arcing,electrical breakdown of air and the various types of circuit breakers.I was also told about interlocking of the circuit breakers.Circuit breaker is one which can make or break the circuit on load and even on faults. Practically a circuit breaker consists of instrument control,bus bar,breaker and cable to load.Various type of circuit breakers are described as follows:
