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HIRAKUD POWER PLANT
a PROJECT REPORT ON CAPTIVE POWER PLANT
For 467.5MW Thermal power plant HINDALCO-Hirakud Power At Hirakud, Sambalpur(Dist), Odisha
Prepared By: Archana NayakSuprava SohelaPrativa Rani BhueMechanical Engg.(2013-17) VEER SURENDRA SAI UNIVERSITY OF TECHNOLOGY (VSSUT) ,BURLA Sambalpur, Odisha
EXECUTIVE SUMMARY Introduction Description Brief discussion about power plant profile Fuel processing parameters Boiler EconomiserCycloneElectrostatic precipitatorSteam Turbine Steam generatorConclusion Reference
HINDALCO-HIRAKUD POWER is a coal based Thermal Power plant which is located at Hirakud, Dist: Sambalpur. The nearest Railway station is Sambalpur Junction which is about 12 kms from plant. Its a CPP (Captive Power Plant) and it has basically 2 branches. One is Power generation and another is Smelter. This power plant generates its own power and utilises for smelting and auxiliary consumption. In addition to that it exports some power to grid.
DescriptionThis power plant has 5 units. It is capable of generating 467.5 MW.As it is a coal based thermal power plant it uses coal as its fuel for boiler. It collects coal from its own mine i.e. Talabira mines which is at a distance 60kms from plant. The daily input of coal is 7KT/day.
The coal based thermal power plant comprises of following units
Steam generator Steam turbine Coal handling system Ash handling System Air cooled Condenser ESP Power plant stack Fuel system Utilities & Services
General Requirement details: Water requirement: 900m3/hr. Source: Reservoir, Hirakud
Use of limestone to reduce emission Use of environmental friendly CFBC Technology Use of Air cooled condenser to reduce coal consumption ESP to minimize the emission of particulate matter Fire protection system Dust Suppression system
Brief discussion about power plant profile
Hindalco-Hirakud power consists of 5 units. Means here 5 turbines and 13 boilers are present. U # 1 is capable of producing 67.5MW power. And two boilers are connected to it. U # 2, U # 3, U # 4 have the capacity of producing 100MW power and 3 boilers are assisted to each unit. U # 5 has the capacity of producing 100MW power & two boilers are assisted. Hence the plant is capable of producing 467.5 MW. As per the demand of smelter its producing the power.
There are three basic circuits in a boiler:(a) water & steam that includes the boiler feed pump (BFP).(b) coal & fly ash that includes the drag chain conveyor (DCC).(c) air & flue gas that includes the ID fan PA fan & SA fan.
Two main terms related to boiler are:(a) mounting that includes safety valve, pressure gauge, level probe etc..(b) accessories that includes ID fan, PA fan, SA fan, DCC, BFP etc..
Water circuit Boiler feed pump (BFP) (around 210oc) ECO 01 ECO 02 (250oc) Evaporator Drum Screen
(510+- 5 oc) (300 oc) Super heater 01
SH 01 Downcomer SH 02 SH 03
Coal circuitIN BOILER:DCC Furnace
Dumping ground Hoppers
Air circuit... PA fan
TA fan SA fan APH
Fuel processing parameters: COAL MINE COAL YARD PRIMARY CRUSHER SECONDARY CRUSHER FEED COAL CONVEYING COAL BUNKERS BOILERS
The fuels burnt in these boilers include low-grade coal, biomass, sludge, waste plastics, waste tires.
WHAT IS A BOILER...?According to IBR 1923 boiler is a closed vessel used for generation of steam for power generation under temperature and pressure by combustion of fuel and air. Boiler is suspended from the top on four columns and kept free from the bottom side for free expansion on downward direction.
SCHEMATIC DIAGRAM OF BOILER...
Feed water is fed to the boiler drum through the economiser.Water then enters in bottom ring header through six numbers of down comers.
PROCESS OF COMBUSTION...There are nozzles on the sand bed through which primary air (pa) enters that helps in fluidising the sand and heats it upto 510 degree celcius.The oil is introduced through the oil gun in the hgg area and coal through drag chain conveyor.
The coal also gets fluidised and the temperature rises as combustion ocurrs.The heat energy developed by combustion of coal in furnace is utilized for the evaporation of water in water walls. As the density of steam is lower than water ,this water steam mixture enters in boiler drum without help of any pump. This is called natural circulation
The main mechanism behind it is CFBC technology i.e., circulating fluidised bed combustion.
It utilises the fluidized bed principle in which crushed (6-12 mm size) fuel and limestone are injected into the furnace.
The particles are suspended in stream of upwardly flowing air (60 70% of the total air) which enters the bottom of the furnace through air distribution nozzle. The fluidizing velocity in circulating bed ranges from 3.7 to 9 m/s.
In boiler drum steam is separated from the mixture.Steam that comes out of boiler is called saturated steam. This saturated steam is then passed through number of superheaters.
When coal is burned in the boiler furnace, hot flue gases pass through the first pass and then to the second pass to the exit of boiler. Economiser and primary superheaters are placed in second pass one above the other, economiser being placed at the exit. The temp. of the flue gases in the combustion zone is 1110 oc. The temp. of flue gas gradually decreases to 400 oc when it leaves second pass.The flue gas then goes through air pre heaters where its temp. Drops down to 140oc.
Bottom ash falls in the bottom hopper and after crushing it is transferred to ash handling plant .Fly ash alongwith the flue gases goes through ESP where fine ash is taken out and send to the ash handling plant for further processing to the ash bunds.Boiler drum, superheater and reheaters are fitted with safety valves for safety against the high pressures of the steam.
What is an Economizer?
An economiser is a mechanical device which is used as a heat exchanger by preheating a fluid to reduce energy consumption.
In asteam boiler, it is a heat ex-changer device that heats up fluids or recovers residual heat from the combustion product i.e. flue gases in thermal power plant before being released through the chimney.
Working principle of an economiser...The recovered heat is in turn used to preheat the boiler feed water, that will eventually be converted to super-heated steam.
Thus, saving on fuel consumption and economising the process to a large extent
Advantages and Benefits of Economizer
It recovers more heat of flue gases which normal air pre-heater can not do.Due increase in fuel prices, all power plants are facing pressure for increasing boiler efficiency. So by using economizer, this pressure can be minimized.Power plants where it is not used, large quantity of water is required to cool the flue gas before desulphurization which is minimized by using economizers.The efficiency of power plant reduced when steam air pre-heater required steam.
WHAT IS A CYCLONE...?Cyclones are simple tanks with no moving parts and have been used for wood dust separation for over seventy years. Cyclones are made up of just a few parts, an air inlet, an outer cylinder, an air outlet, and cone with dust chute that connects to a collection bin. Dirty air comes in through the inlet.Heavy particles i.e., the unburnt coal falls at the bottom outlet.This is connected to the coal inlet to allow the unburnt particles to undergo combustion.
Advantages:Simple constructionNo moving components Little maintenanceLow investment and functioning costsConstant pressure dropSaves roomDry relief during wet cyclone
There are two types of cyclone:HOT CYCLONECOLD CYCLONEIn this type the temp. is greater than 700oc
Here the temperature remains between 400-500oc.
ELECTROSTATIC PRECIPITATOR...ESP is used for reduction of particulate matter (PM) in flue gas generated due to the combustion of Indian coal. This coal is characterized by high ash content, low calorific value and low sulphur content resulting in the generation of a very large amount of highly electrically-resistive fly-ash
HOW DOES AN ESP WORK...?It has electrodes through which electricity in the range of 10000 kV is passed when flue gas enters into the precipitator.Hence the gas gets divided into (+)ve and (-)ve ions which are then attracted towards the electrodes and stick to it.In hirakud there is a hammering operation which hammers the electrode from time to time so that the contents get collected in the hopper below which are then transferred.
A low efficiency (65%), high throughput cyclone is considered for pre-cleaning flue gas and the ESP is designed for removal of the remaining 35% fly-ash from the flue gas.
WHOLE PROCESS OF A POWER PLANT...
WHAT IS A TURBINE...?Turbine is a prime mover.It converts potential energy into kinetic energy.Here the temperature & pressure is around 510oc & 90 kg respectively. It is primarily of three types: impulse, reaction & compound.The key parts of a turbine are a set ofblades (41 blade assembly in Hirakud power plant)that catch the moving fluid, a shaft oraxlethat rotates as the blades move, and some sort ofmachinethat's driven by the axle.Each set of blade is called a stage.
There are two types of blades:Fixed bladeThese blades are mounted on the casting.These are used to direct the steam towards the direction of moving blades.Moving bladeThese are mounted on the rotor.These blades rotate on their own & are exactly responsible for converting potential energy into kinetic energy.
IMPULSE TURBINE...In animpulse turbine, a fast-moving fluid is fired through a narrow nozzle at the turbine blades to make them spin around. The blades of an impulse turbine are usually bucket-shaped.
so they catch the fluid and direct it off at an angle or sometimes even back the way it came (because that gives the most efficient transfer of energy from the fluid to the turbine). In an impulse turbine, the fluid is forced to hit the turbine at high speed.
REACTION TURBINE...In areaction turbine, the blades sit in a much larger volume of fluid and turn around as the fluid flows past them. A reaction turbine doesn't change the direction of the fluid flow as drastically as an impulse turbineIt simply spins as the fluid pushes through and past its blades. Wind turbines are perhaps the most familiar examples of reaction turbines.
WORKING OF A TURBINE...Steam in superheated condition from boiler enters turbine through valve called control valve(4 in Hkd)Opening & closing of CV is not decided manually.Before CV there are stop valves called Emergency stop valves (ESV).ESV opens only when all the factors like temp. & pressure are satisfied.ESV is also hydraulically operated.There are nozzles on the surface of the blades that direct the flow of the steam.
Initial blades are pure impulse.Here the 90 kg pressure is directly converted into enthalpy.Subsequently, the 90 kg & 510oc goes on drooping & at the end, pressure & temp. around (0.5-0.8)kg/cm2 (45-52)oc respectively is obtained.This is because of the compounding factor which is necessary to increase enthalpy.
The last stage is the exhaust stage.It leaves the heat out & into the condenser from where it is transferred to the CEP (condensate extraction pump).An ejector type vaccum pump is used to suck the air out to allow the steam to enter it.This is cooled by surface type heat exchanger where pipes containing cold water is entered into the condenser.
Tip loss means the process of loss of steam through the tip of blades hence the gap between the blades is kept less (usually in microns). The steam lost through these parts are subsequently collected and are taken to HP 1, HP 2, dearator, LP 1 & LP 2. The heat from these stages are then used to heat up the circulating water hence forming a close circuit.
Turbine in a thermal power plant
Steam generator... The steam enters in steam turbine and due to the heat energy of steam, turbine rotates at about 3000 rpm. The turbine is directly coupled to the generator rotor. Electricity is generated as per the Faradays Law in generator.
FARADAYS FIRST LAW : Whenever a conductor cuts magnetic flux,an emf is induced in that conductor.FARADAYS SECOND LAW : The magnitude of the induced emf is equal to the rate of change of flux linkages.
In alternator time varying magnetic field is produced by rotating field winding with help of turbine. Field windings are wound over rotor of the alternator and rotor is coupled to the turbine. Field windings are connected to the excitation system through slip rings. From excitation circuit, D.C. current is allowed to pass through the field windings and produces a magnetic field. So when the rotor rotates, D.C. current carrying field windings also rotates and produces a time varying magnetic fieldx
This time varying magnetic field is cut by the stator windings of the alternator and emf is induced in it of the order of 15.75 KV as per the Faradays Law. Electricity produced in the stator is then passed though bus ducts to the generator transformer. GT increases the voltage level from 15.75 KV to 400 KV. This transformer is connected to 400 KV buses in switchyard through isolators and a circuit breaker.
Steam generator in hirakud, power thermal power plant...
Cooling tower circuit...
Demineralising plant in hirakud power...
Conclusion... The HINDALCO- HIRAKUD POWER is one of the major power plant in ODISHA as well as in INDIA. We are very grateful that we got the opportunity to join the Industrial training project in your Industry. We are very thankful to all the respected Employees of the plant who guided us to get all the knowledge about the power plant.
Bureau of Energy efficiency www.google.com Wikipedia S.B. Mishra sir Prem Kumar Sir