1.A SUMMER TRAINING PRESENTATION 0N NATIONAL THERMAL POWER PLANT KAHALGAON (BIHAR)SUBMITTED TO:Prof. R K Mathur sir Dept. Of mechanicalSUBMITTED BY: Akhilesh kumar Roll No-11001184006 B.Tech(Mechanical engg.)

2. Introduction Coal Handling Boiler & Auxillary Turbine System Ash Handling Off- siteCONTENTS 3. NTPC OPERATION &MAINTENANCE Boiler Maintenance Department Turbine Maintenance Department Ash Handling Departament Off-site Maintenance Departament 4. INTRODUCTIONIndias largest power company ,NTPC was set up in 1975 to accelerate power development in india.NTPC is emerging as a diversified power major with presence in the entire value chain of the power generation ,which is the mainstary of the company ,NTPC has already ventured into consultancy.power trading,Ash utilisation and coal mining kahalgaon super thermal power station (khstpp) is located in kahalgaon in Bhagalpur district of bihar.The power plant is one of the coal based power plant of NTPC. CAPACITY :- The Total installed capacity of the plant is 2340 mw. 5. NTPC, Kshpp Project Location : Kahalgaon ,Dist-Bhagalpur(Bihar),813214 Total Land : 3,360 acres Land for plant : 883 acres Land for township : 432 acres Land for Ash dyke :1395 acres Configuration : stage -1 (4*210 MW): stage -2: phase 1 (2*500 MW) : Phase 2 (1*500 MW) Sourse of coal : Rajmahal coal field of ECL Fuel Requirement : 4.1 million ton per year stage -1 : 6.62 million ton per year for stage -2 : 3 million ton per year for stage -2 Sourse of water : Ganga River 6. NTPC Make of water Requirement : 7500 m3/hr (stage-1): 6000 m3/hr (stage-2) Cooling water system : closed cycles induced Draft cooling tower Approved capacity : stage 1. 840 mw + stage 2. 500 mw Commersilation :unit 1.-(210 mw) march ,1992 : unit 2.- (210 mw) march, 1994 : unit 3.- (210 mw) march ,1995 : unit 4.- (210 mw) march , 1996 :unit 5.-(500 mw) march ,2007 :unit 6.- (500 mw) march ,2008 : unit 7- (500 mw) june, 2009 7. NTPCLAYOUT OF POWER PLANT :- 8. Coal Handling System Equipment Wagon Trippler Conveyor Belt Pulleys Take Ups Skirt Board Scrappers Magnetic seprator Vibrating screen Crushers 9. CRUSHERS To crush the coal from 200mmto 20mm size received from vibrating screen Crusher hammer are made of MAGNEESE STEEL . Hammer row -4(stage 1) (a)Row-1 & 2 =18 hammer each (b)Row-3&4=20 hammers each1 December 2013No of hammer in each Crusherstage-1 = 76 hammers stage-2 = 92 hammers Weight of each hammer=18.5kg Crushing motor rating -740kw/3.3kv Life of hammer =4 lac MT of coal Normal capacity=600 tons/hr PMI Revision 009 10. CONVEYOR BELTS Made of diff. Layers or piles of fabric duck with rubber protected by a rubber cover on both sides & edges. Fabric duck are designed to withstand tension created in carrying the load . Nylon rubber cover protect the fabric duck. Material =fire resistant grade. Belt Width=1600 mm. Strength= 1000/1250 kN. Belt speed=3.2-3 m/s. Belt length=20km.1 December 2013PMI Revision 0010 11. PULLEYS NTPCMade of mild steel. Rubber coating is used to increase friction factor between belt & pulley (rubber laggingShell dia-500mm. Shaft dia-1400mm. Pulley length-1800mm. Shaft length-2350mm(bearing centre to centre) 1 December 2013PMI Revision 0011 12. DRIVE UNITNTPCMotors coupled to reduction gear with the help of flexible/fluid coupling on the high speed shaft of the Gear box Flexible coupling on the input sideTAKE UPS Take up pulley to facilitates Necessary tension for the drive to operate the belt Sag at a point where requires horse power will be at a minimum and load will move with least disturbance over idlers 1 December 2013PMI Revision 0012 13. NTPCSKIRT BOARD Used with chutes at trail end. Guides material centrally on the belt while loading until it has settle down on the beltSCRAPPERS Placed at discharge pulley in order to clean the carrying side of belt. It avoids the wear of return idlers due to build up material.1 December 2013PMI Revision 0013 14. BOILER MAINTENANACE DEPARTMENT BOILER: Steam generating device for specific purpose. Capable to meet variation in load demand. Capable of generating steam in a range of operating pressure and temperature. For utility purpose ,it should generate steam uninterrupediy at operatingpressure and temperature for running steam turbine. BOILER/STEAM GENERATOR : Raw material for design of boiler 1.coal frommines 0 Generating heat energy 2. Ambient air 0 Air for combustion 3. Water from natutal resources (river ,ponds ) 0 Working fluid for steam generation possessing heat energy A 500 MW steam generator consumers about 8000 tonnes of coal every day. It will be considered if it requires about 200 cubic meter of D M water in a day. It will produce about 9500 tonnes of carbon di- oxide evert day. 15. BOILER AUXILARIES There are three part of Boiler :1.Milling system 2.Rotatory part 3.pressure part 1.MILLING SYSTEM: Coal Bunker:- These are in process storage silos used for storing crushed coal from the coal handling system .generally,these are made of welded steel plates normally these are six such bunker supplying coal of the corresponding mills .Those are located on top of the mill so as aid in gravity feeding of coal. Coal feeder:- Each mill is provided with a drag link chain/rotary /gravametic feeder to transport raw coal from the bunker to the inlet chute leading to mill at desired rate . MILLS:- These are six mill (25persent capacity each) for every 200mw unit ,located adjacent to the furnace at (o) m level .There mills pulverise coal to be desired fineness to be feed to the furnace for combustion. It is used to crush the coal into powder form (80 micron).These are 10 mills for the 500mw unit ,located adjacent to the furnace at o level .These mills pulverised coal to the desined fineness to be fed to the furnace for combustion. 16. CLASSIFICATION OF MILLS VERTICAL SPINDLE BOWL/ BALL & RACE XRP (BHEL)TUBE PRESSURIZEDE MILLS (BABCOCK)MPS 17. BALL MILL ANIMATION 18. NTPC2.ROTATORY PART : P A Fan : The primary air fan (2 per unit -50 percent capacityeach ) are designed for handling atmospheric air upto a temperature of 50 deg c .These fan are located at (0) m level near the boiler . F.D Fan :- The forced draft fans (2 per unit -50 percent capacity each) are designed for handling secondary air for the boiler .These fan are located at o m level near the P A fan. I D Fan:- There are two indused Draft fans per boiler located between the electrostatic precipitator and the chimney . These fans are used for sucking flue gas from furnace 19. TURBINE MAINTENANCE DEPARTMENT (TMD) TURBINE :- A steam turbine is a rotating device which converts thermalenergy into mechanical energy. OPERATING PRINCIPLE :- A steam turbine has two main part -1) cylinder(stater) and the rotor . The cylinder or rotor is a steel or cast iron housing usually divided at the horizontal centre line.its havies are bolted together for easy access .The cylinder contains fixed blade carred by rotor .each fixed biade set is mounted in diphram located in front of each disc on the rotor or directly in the casing . A disc and diphram pair a turbine stage.steam turbine can have many stage the rotor is a rotating shaft carries the moving blades .on the outer edges of either disc or drum . The blade rotate as the rotor revolves .The rotor of a large steam turbine consists of high intermediate ,low pressure turbine section . In a multiple stage ,steam at the high pressure and high temperature enter s the first row of fixed blades or nozzle through an inlet value .As the steam passes through the fixed blades or nozzles it expands and its velocity increases the high velocity jet of steam strkes the first set of moving blades. 20. 21 HPT3 IP T4567LPT GENERATOR EXCITERTHREE STAGE TURBINE : HIGH PRESSURE TURBINE (HPT) INTERMEDIATE PRESSURE TURBINE (IPT) LOW PRESSURE TURBINE (LPT) SEVEN NOS JOURNAL BEARINGS BEARING N0. 2 THRUST CUM JOURNAL BEARING FOUR NOS RIGID COUPLINGS BETWEEN HP-IP TURBINE IP-LP TURBINE LP-GENERATOR GENERATOR - EXCITERCONDENSER 21. SINGLE STEAM FLOW OF TWO SHELL (CASING) DESIGN OUTER CASING IS OF BARREL TYPE AND HAS NEITHER ON AXIAL OR RADIAL FLANGE. DUE TO THE PERFECT SYMMETRIC DESIGN OF THE OUTER CASING AND UNIFORM WALL THICKNESS AT ALL SECTIONS, PREVENTS MASS CONCENTRATIONS WHICH WOULD CAUSED HIHG THERMAL STRESSES AND REMAINS LEAK PROOF DURING QUICK CHANGES IN TEMPERATURE DURING START UP AND SHUT DOWN. THE INNER CASING IS AXIALLY SPLIT IS ALMOST CYLINDRICAL IN SHAPE AS THE JOINTS FLANGES ARE RELIEVED BY HIGHER PRESSURE ACTING FROM THE OUT SIDE. CASING IS MADE OF CREEP RESISTING CHROMIUM-MOLYBDENUM-VANADUIUM (Cr-Mo-V) STEEL CASTING. THE TURBINE HAS 2 MAIN STOP VALVES (ESV) AND 2 CONTROL VALVES (CV)LOCATED SYMMETRICALLY TO THE RIGHT AND LEFT OF THE CASING. THE VALVES ARE ARRANGED IN PAIRS WITH ONE STOP VALVE AND ONE CONTROL VALVE IN A COMMON BODY. EACH ESV AND CV HAS A DEDICATED HYDRAULIC SERVOMOTOR. THE STEAM LINES FROM ESV & CV ARE CONNECTED TO THE INLET CONNECTIONS OF THE OUTER CASING BY BREECH NUTS. THE EXHAUST END OF HPT HAS A SINGLE OUT LET CONNECTION FROM BOTTOM. 22. THE IP TURBINE IS OF DOUBLE FLOW CONSTRUCTION WITH TWO NOS HORIZONTALLY SPLIT CASINGS ( INNER & OUTER CASING). THE HOT REHEATED (HRH) STEAM INTERS THE INNER CASING AT THE MID SECTION FROM TOP AND BOTTOM AND EXPENDS IN OPPOSITE SIDE IN TWO BLADE SECTIONS AND COMPENSATE AXIAL THRUST. THE INNER CASING CARRIES THE STATIONARY BLADING. THE IP STOP AND CONTROL VALVES 2 NOS ARE SUPPORTED ON THE FOUNDATION COVER PLATE BELOW EL 17.00 M FLOOR IN FRONT OF TURBINE GEN UNIT. CASING IS MADE OF CREEP RESISTING CHROMIUM-MOLYBDENUMVANADUIUM (Cr-Mo-V) STEEL CASTING. THE SHAFT IS MADE OF HIGH CREEP RESISTANCE Cr-Mo-V STEEL FORGING. 23. LP TURBINE CASING CONSISTS OF DOUBLE FLOW UNIT AND HAS A TRIPLE SHELL WELDED CASING. THE OUTER CASING CONSISTS OF FRONT AND REAR WALLS, TWO LATERAL LONGITUDINAL SUPPORT BEAMS AND THE UPPER DOME AND CONNECTED TO CONDENSER BY WELDING. THE INNER-INNER & INNER-OUTER CASING CARRIES THE TURBINE GUIDE BLADES AND DIFFUSER. STEAM ADMITTED TO THE LP TURBINE INNER CASING FROM IP TURBINE FROM BOTH LEFT AND RIGHT SIDE HORIZONTALLY. EXPANSION JOINTS ARE INSTALLED IN THE STEAM PIPING TO PREVENT ANY UNDESIRABLE DEFORMATION OF THE CASINGS DUE TO THERMAL EXPANSION OF THE STEAM PIPING. 24. HP TURBINE MOVING AND STATIONARY BLADES : 1. 2. 3. HP TURBINE BLADING CONSISTS OF 17 REACTION STAGES WITH 50 % REACTION. BLADES ARE HAVING THREE MAIN PARTS : AEROFOIL : IT IS THE WORKING PART OF THE BLADE WHERE STEAM EXPANSION TAKES PLACE. ROOT : TI IS THE PORTION OF THE BLADE WHICH IS HELD WITH ROTOR OR CASING SHROUDS : END PORTION OF BLADES ARE HELD TOGETHER THE STATIONARY AND MOVING BLADES OF ALL STAGES ARE PROVIDED WITH INVERTED T-ROOTS. ALL THESE BLADES ARE PROVIDED WITH INTEGRAL SHROUDS WHICH AFTER INSTALLATION FORM A CONTINUOUS SHROUD. THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE INSERTION SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE WHICH IS FIXED BY GRUB SCREWS. SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE SHAFT TO REDUCE LEAKAGES LOSSES AT THE BLADE TIPS. 25. IP TURBINE MOVING AND STATIONARY BLADES : IP TURBINE BLADING CONSISTS OF 12 REACTION STAGES PER FLOW WITH 50 %REACTION. THE STATIONARY AND MOVING BLADES OF ALL STAGES ARE PROVIDED WITH INVERTED T-ROOTS. ALL THESE BLADES ARE PROVIDED WITH INTEGRAL SHROUDS WHICH AFTER INSTALLATION FORM A CONTINUOUS SHROUD. THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE INSERTION SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE WHICH IS FIXED BY GRUB SCREWS. SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE SHAFT TO REDUCE LEAKAGES LOSSES AT THE BLADE TIPS. 26. LP TURBINE MOVING AND STATIONARY BLADES (FIRST 3 STAGES) : LP TURBINE BLADING CONSISTS OF 6 REACTION STAGES PER FLOW WITH 50% REACTION. THE STATIONARY AND MOVING BLADES OF FIRST THREE STAGES ARE PROVIDED WITH INVERTED T-ROOTS. ALL THESE BLADES ARE PROVIDED WITH INTEGRAL SHROUDS WHICH AFTER INSTALLATION FORM A CONTINUOUS SHROUD. FIRST THREE GUIDE BLADES ARE MOUNTED ON INNER-INNER CASING. THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE INSERTION SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE WHICH IS FIXED BY GRUB SCREWS. SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE SHAFT TO REDUCE LEAKAGES LOSSES AT THE BLADE TIPS. 27. CONDENSER IS A SURFACE TYPE CONDENSER WITH TWO PASS ARRANGEMENT. COOLING WATER IS PUMPED INTO EACH OF CONDENSER PASS BY VERTICAL CW PUMPS THROUGH THE INLET PIPE. WATER ENTERS THE INLET CHAMBER OF FRONT WATER BOX AT THE BOTTOM PASSES HORIZONTALLY THROUGH THE TITANIUM TUBES TO THE WATER BOX AT THE OTHER END, TAKES A TURN PASSES THROUGH THE UPPER CLUSTER OF THE TUBES AND REACHES THE OUT LET CHAMBER AT THE TOP IN THE FRONT WATER BOX AND LEAVES THE CONDENSER THROUGH OUTLET PIPE. STEAM EXHAUSTED FROM THE LP TURBINE WASHING THE OUTSIDE OF THE CONDENSER TUBES LOSSES ITS LATENT HEAT TO THE COOLING WATER AND CONVERTED INTO WATER IN THE STEAM SIDE OF THE CONDENSER. THIS CONDENSATE COLLECTS IN THE HOT WELL, WELDED TO THE BOTTOM OF THE CONDENSER.CONDENSER DESIGN DATA : COOLING WATER FLOW : 54300 M3/Hr. COOLING WATER SURFACE AREA : 35603 M2 NO. OF COOLING TUBES : 24398 NOS ( CONDENSING ZONE:22688 NOS AND AIR COOLING ZONE :1710 NOS) TUBE MATERIAL : TITANIUM SB-338 GRADE-II MAIN TUBE PLATE : MS WITH TITANIUM CLADED. WATER BOX : MS WITH FRE LINING ( GLASS FIBRE REINFORCED EPOXY LINING) OF 3MM THICKNESS. 28. ASH HANDLING DEPARTMENT WHAT IS ASH ? Ash is the residue remaining after the coal has been incinerated to constant weight under standard conditions. Ash is oxidised form of the mineral matters present in coal. Typical ash composition : SiO2, Al2O3, Fe2O3, CaO, MgO etc. Coal with more SiO2 & Al2O3, Ash MP > 1400C Coal with more Fe2O3, CaO & MgO, Ash MP < 1100C 28 29. WHY ASH HANDLING? Ashcontent of Indian coal used in power station is about 30 to 40 %. A typical 2000 MW station produce around 9000T to 12000T of ash per day. This huge amount of ash needs to be disposed off continuously. Necessary care to be taken for preventing pollution AshHandling system takes care the above requirement29 30. Fly Ash Handling System FA iscollected from Air heater hopper, Eco hopper and ESP hopper. Either through flushing apparatus or hydrobactur system. In Flushing apparatus system ash is allowed to fall in flushing apparatus under gravitation. Water jet in flushing apparatus carries away the ash to FA trench High pressure jets further carries it to FA sump. Series pumping carries the ash slurry to FA pond.1 December 2013PMI Revision 0030 31. Bottom ash Handling System BA canbe collected at furnace bottom as Wet or Dry form. Wet bottom ash system consists of i)Trough seal, ii)BA gate, iii)Hopper, iv)Scrapper Conveyer, v)Clinker grinder, vi)BA trench, vii)BA tank, viii)BA pump, ix)BA pond. Dry BA consists of i)Trough seal, ii)BA gate, iii)Hopper, iv)Scrapper Conveyer, v)Clinker grinder, vi)Silo. Trough seal : A channel around the furnace bottom filled with water where the furnace bottom end is immersed in water. This is to prevent air ingression in the boiler during operation.31 32. OverburdenSurge Pile Pulverize (-150)Coal SeamElectrostatic PrecipitatorBoilerFlue GasFlue Gas Fly Ash Bottom AshFly AshFly AshBottom AshSmoke Stack 32 33. Ash volumes and properties FurnaceESP(1300 - 1500 C) Economizer100 %Stack10-20 %1%Stage C: 3 %Stage A: 80 %Bottom Ash Eco AshStage B: 17 %Air preheater APHPulverize d CoalCoalElectrostatic PrecipitatorAPH Ash Fly ash1%80-90 % AshFineness 33 34. OFF-SITE DEPARTMENT Water Treatment Cooling Tower 35. Why water treatment? Raw water contains many dissolved minerals and organic materials. At high temperature certain minerals left scaling on the tube metal of the boiler and cause permanent damage. Some dissolved minerals leads to corrosion of tube metals. Some leads to foaming At high pressure and temperature an element, silica can be carried away with steam causing damage to turbine low pressure stage. A Thermal Power Station needs water of varying quality for different process and hence the requirement. The performance and life expectancy of the station greatly depends on water chemistry compliance.1 December 2013PMI Revision 0036 36. Type of water treatment the type of demineralization process chosen for a powerstation depends on three main factors : The quality of the raw water. The degree of deionisation i.e. treated water quality Selectivity of resins.1 December 2013PMI Revision 0037 37. Steps of treatment process Aeration of raw water Adding chemicals for bacteria removal Adding chemicals for sedimentation of suspended particles Flocculation Filtration Ion Exchange process water treatment process is generally made up of two sections : Pretreatment section Demineralisation section1 December 2013PMI Revision 0038 38. DescriptionStage-ITower TypeStage-IIInduced Draft Multi Fill Counter Flow Make M/S Gammon India Circulating water flow 30,000 / tower M3/hr./tower. Hot CW inlet temp. 43oCInduced Draft Multi Fill Counter Flow M/S NPCC Ltd. 33,000 M3/hr.Cold CW Out let temp. 33oC33oCRange9oC10oC42oC 39. COOLING FAN DescriptionStage-IStage-IITypeAxial FlowAxial FlowNo. of fans / tower1612Diameter24 feet28 feetNo. of blade67Blade angle13o13oFan speed151 Rpm118 Rpm35 KW56 KWAbsorbedpower 40. NTPC 41. Maintenance practices in CT Daily walk down monitoring of CT cells Cold water basin cleaning Algae removal from splash bars Tree trimming /pruning at nearby CT area Maintaining clean walkway around CT Gear box to be run for an hour fortnightly during opencycle Prevention of air ingress at inspection door, transmission shaft, oil piping, expansion joints etc Fabricated nozzle fitting in hot water channel in CT ST # II 42. NTPC