REPORT ONINDUSTRIAL TRAINING

ATBADARPUR THERMAL POWER STATION, NEW DELHI

SUBMITTED BYROHIT KAPOOR080909382

DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERINGMANIPAL INSTITUTE OF TECHNOLOGYACKNOWLEDGEMENT

I wish to express my appreciation to all those with whom I worked interacted and whose thoughts and insists helped me in increasing my knowledge and understanding of working in an organization.I feel great pleasure in presenting my obligation to Mr. Man Mohan (Dy. Manager) who allowed me to undergo training at BTPS.I acknowledge with deep sense of gratitude to Mr. G.D. Sharma (training coordinator) for providing his esteem guidance and vast knowledge to help me complete my training.Im very thankful to the various departments in charges for helping me clear my concepts about the plant and providing me with required information.Finally, I owe my thanks to faculty members and training and placement department of my college, Manipal Institute of Technology who helped and guided me for the training.

CONTENTSPage no. 1.0 Introduction 4-81.1 NTPC 1.2 Power Generation in India 1.3 Badarpur Thermal Power Station (BTPS) 2.0 Objective 93.0 Work Done During The Training Period 10-403.1 Electricity From Coal 3.2 Boiler Maintenance Division (BMD)3.3 Plant Auxiliary Maintenance (PAM)3.4 Pollution Control and Waste Management4.0 Inference 415.0 Bibliography 42

1.0 INTRODUCTION

Thermal power station employs a great no of equipment performing number of complexity process. The ultimate aim being the production of electricity in order to have stable generating conditions always balance has to be achieved so that heat input is equal to electricity output and losses. Efficiency of the plant is expressed in terms of heat rate which is the kilocalories burnt to get 1 kWhr.

1.1 NTPCIndias 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 business. Apart from power generation, which is the mainstay of the company, NTPC has already ventured into consultancy, power trading, ash utilization and coal mining. NTPC ranked 317th in the 2009, Forbes Global 2000 ranking of the Worlds biggest companies.

The total installed capacity of the company is 31,704 MW (including JVs) with 15 coal based and 7 gas based stations, located across the country. In addition under JVs, 3 stations are coal based & another station uses naphtha/LNG as fuel. By 2017, the power generation portfolio is expected to have a diversified fuel mix with coal based capacity of around 53000 MW, 10000 MW through gas, 9000 MW through Hydro generation, about 2000 MW from nuclear sources and around 1000 MW from Renewable Energy Sources (RES). NTPC has adopted a multi-pronged growth strategy which includes capacity addition through green field projects, expansion of existing stations, joint ventures, subsidiaries and takeover of stations.NTPC has been operating its plants at high efficiency levels. Although the company has 18.10% of the total national capacity it contributes 28.60% of total power generation due to its focus on high efficiency.

1.2 POWER GENERATION IN INDIANTPCs core business is engineering, construction and operation of power generating plants. It also provides consultancy in the area of power plant constructions and power generation to companies in India and abroad. As on date the installed capacity of NTPC is 27,904 MW through its 15 coal based (22,895 MW), 7 gas based (3,955 MW) and 4 Joint Venture Projects (1,054 MW). NTPC acquired 50% equity of the SAIL Power Supply Corporation Ltd. (SPSCL). This JV Company operates the captive power plants of Durgapur (120 MW), Rourkela (120 MW) and Bhilai (74 MW). NTPC also has 28.33% stake in Ratnagiri Gas & Power Private Limited (RGPPL) a joint venture company between NTPC, GAIL, Indian Financial Institutions and Maharashtra SEB Co Ltd.NTPC has set new benchmarks for the power industry both in the area of power plant construction andoperations. Its providing power at the cheapest average tariff in the country.1.3 BADARPUR THERMAL POWER STATION (BTPS)Badarpur thermal power station (BTPS) is designed and engineered by the central water and power commission (CWP).Approved capacity: 705 MWInstalled capacity: 705 MWLocation: New DelhiCoal source: jharia coal fieldsa) CCL (central coal fields)b) BCCL (bharat cooking coals ltd.)c) ECL (eastern coal fields ltd.)Water source: Agra canalBeneficiary state-New DelhiSize of units- 3x95 MW2x210 MWCommissioning of units:Unit I95 MW1973-75

Unit II95 MW1974-75

Unit III95 MW1974-75

Unit IV210 MW1978-79

Unit V210 MW1981-82

The management of centrally owned BTPC was handed over to NTPC on April 15th 1978.The BTPS under the management of NTPC is generating today at a plant load factor of more than 80% of the total capacity. The turnaround of station has been possible only due to management of station by NTPC.The station was designed and engineered by Central Electricity Authority (CEA) formerly central water and power commission. The plant became operational on July 26th, 1973.presently the station is supplying its entire generation to New DelhiThere are 11 feeders in use at present, 2-Okhla, 2-Sarita Vihar, 2-Mahroli, 2-Noida, 2-Ballabhgarh, and 1-Alwar.

Site selection of power plant Availability of coal-steam power station should be located near mines so minimum cost of fuel is maintained. However if such facility isnt available then adequate facilities should be made for transportation of coal like railway lines which are provided in case of BTPS Availability of water-a large amount of water is necessary for condenser. Therefore such a plant should be located at the bank of river or near a canal like Agra canal in case of BTPS Means of transportation-the power plant should be well interconnected with roads or railways system for efficient transportation material Land properties-land should be cheap and there should be enough land surrounding the plant so that there may be option of expanding. The land should be able to withstand the load of heavy equipment Nearness to load centers-this is very important factor when considering dc transmission. If an ac system is employed then this factor is less important because ac can be transmitted at high voltage with consequent reduction transmission cost that is why it is possible to install the plant away from load centre provided the conditions are favorable Ash disposal facilities-quantity of ash to be handled is 1500-2000 tons per day the disposal of large quantity of ash from the power station can be into river, sea or lake or can be brought into useful purposes like manufacturing of bricks as done by BTPS or for land filling as recently was used by Delhi metro Distance from populated areas-since there is a lot of coal burnt in the power station there will be a lot smoke and fumes that make surrounding of plant very hazardous

2.0 OBJECTIVE

I was appointed to do three-week training at this esteemed organization from 21st JUNE to 10 th JULY, 2010. In these four weeks I was assigned to visit various division of the plant which were

1. Boiler Maintenance Division I (BMD-I)2. Boiler Maintenance Division II (BMD-II) 3. Plant Auxiliary Maintenance (PAM)

The objective of the training at NTPC is to gain experience of three weeks on field, utilize the current engineering concepts, to gain practical knowledge in the field of thermal power generation and understand how an organization works in harmony to produce benefits for both the employees and customers.

3.0 WORK DONE DURING THE TRAINING PERIOD

3.1 ELECTRICITY FROM COALCoal from the coal wagons is unloaded with the help of wagon tipplers in the C.H.P. this coal is taken to the raw coal bunkers with the help of conveyor belts. Coal is then transported to bowl mills by coal feeders where it is pulverized and ground in the powered form.This crushed coal is taken away to the furnace through coal pipes with the help of hot and cold mixture P.A fan. This fan takes atmospheric air, a part of which is sent to pre heaters while a part goes to the mill for temperature control. Atmospheric air from F.D fan in the air heaters and sent to the furnace as combustion air.Water from boiler feed pump passes through economizer and reaches the boiler drum. Water from the drum passes through the down comers and goes to the bottom ring header. Water from the bottom ring header is divided to all the four sides of the furnace. Due to heat density difference the water rises up in the water wall tubes. This steam and water mixture is again taken to the boiler drum where the steam is sent to super heaters for super heating. The super heaters are located inside the furnace and the steam is super heated (540 degree Celsius) and finally it goes to the turbine.Fuel gases from the furnace are extracted from the induced draft fan, which maintains balance draft in the furnace with F.D fan. These fuel gases heat energy to the various super heaters and finally through air pre heaters and goes to electrostatic precipitators where the ash particles are extracted. This ash is mixed with the water to from slurry is pumped to ash period. The steam from boiler is conveyed to turbine through the steam pipes and through stop valve and control valve that automatically regulate the supply of steam to the turbine. Stop valves and controls valves are located in steam chest and governor driven from main turbine shaft operates the control valves the amount used. Steam from controlled valves enter high pressure cylinder of turbines, where it passes through the ring of blades fixed to the cylinder wall. These act as nozzles and direct the steam into a second ring of moving blades mounted on the disc secured in the turbine shaft. The second ring turns the shaft as a result of force of steam on the stationary and moving blades together.

Typical components of a coal fired thermal power station1. Cooling water pump2. Three-phase transmission line3. Step up transformer4. Electrical Generator5. Low pressure steam6. Boiler feed water pump7. Surface condenser8. Intermediate pressure steam turbine9. Steam control valve10. High pressure steam turbine11. Deaerator Feed water heater12. Coal conveyor13. Coal hopper14. Coal pulverizer15. Boiler steam drum16. Bottom ash hoper17. Super heater18. Forced draught (draft) fan19. Reheater20. Combustion air intake21. Economizer22. Air preheater23. Precipitator24. Induced draught (draft) fan25. Fuel gas stack

The description of some of the components written above is described as follows:

1. Cooling towersCooling Towers are evaporative coolers used for cooling water or other working medium to near the ambivalent web-bulb air temperature. Cooling tower use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries, Chemical plants, power plants and building cooling, for example. The tower vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 meters tall and 100 meters in diameter, or rectangular structure that can be over 40 meters tall and 80 meters long. Smaller towers are normally factory built, while larger ones are constructed on site. The primary use of large , industrial cooling tower system is to remove the heat absorbed in the circulating cooling water systems used in power plants , petroleum refineries, petrochemical and chemical plants, natural gas processing plants and other industrial facilities . The absorbed heat is rejected to the atmosphere by the evaporation of some of the cooling water in mechanical forced-draft or induced draft towers or in natural draft hyperbolic shaped cooling towers as seen at most nuclear power plants.

2. Electrical generator An Electrical generator is a device that converts kinetic energy to electrical energy, generally using electromagnetic induction. The task of converting the electrical energy into mechanical energy is accomplished by using a motor. The source of mechanical energy may be a reciprocating or turbine steam engine, , water falling through the turbine are made in a variety of sizes ranging from small 1 hp (0.75 kW) units (rare) used as mechanical drives for pumps, compressors and other shaft driven equipment , to 2,000,000 hp(1,500,000 kW) turbines used to generate electricity.

3. TurbinesThere are several classifications for modern steam turbines.Steam turbines are used in all of our major coal fired power stations to drive the generators or alternators, which produce electricity. The turbines themselves are driven by steam generated in Boilers or steam generators as they are sometimes called.Electrical power station use large steam turbines driving electric generators to produce most (about 86%) of the worlds electricity. These centralized stations are of two types: fossil fuel power plants and nuclear power plants. The turbines used for electric power generation are most often directly coupled to their-generators .As the generators must rotate at constant synchronous speeds according to the frequency of the electric power system, the most common speeds are 3000 r/min for 50 Hz systems, and 3600 r/min for 60 Hz systems. Most large nuclear sets rotate at half those speeds, and have a 4-pole generator rather than the more common2-pole one.Energy in the steam after it leaves the boiler is converted into rotational energy as it passes through the turbine. The turbine normally consists of several stage with each stages consisting of a stationary blade (or nozzle) and a rotating blade. Stationary blades convert the potential energy of the steam into kinetic energy into forces, caused by pressure drop, which results in the rotation of the turbine shaft. The turbine shaft is connected to a generator, which produces the electrical energy.

4. Boiler feed water pumpA Boiler feed water pump is a specific type of pump used to pump water into a steam boiler. The water may be freshly supplied or retuning condensation of the steam produced by the boiler. These pumps are normally high pressure units that use suction from a condensate return system and can be of the centrifugal pump type or positive displacement type.

Construction and operation:Feed water pumps range in size up to many horsepower and the electric motor is usually separated from the pump body by some form of mechanical coupling. Large industrial condensate pumps may also serve as the feed water pump. In either case, to force the water into the boiler; the pump must generate sufficient pressure to overcome the steam pressure developed by the boiler. This is usually accomplished through the use of a centrifugal pump.Feed water pumps usually run intermittently and are controlled by a float switch or other similar level-sensing device energizing the pump when it detects a lowered liquid level in the boiler is substantially increased. Some pumps contain a two-stage switch. As liquid lowers to the trigger point of the first stage, the pump is activated. I f the liquid continues to drop (perhaps because the pump has failed, its supply has been cut off or exhausted, or its discharge is blocked); the second stage will be triggered. This stage may switch off the boiler equipment (preventing the boiler from running dry and overheating), trigger an alarm, or both.

5. Steam-powered pumpsSteam locomotives and the steam engines used on ships and stationary applications such as power plants also required feed water pumps. In this situation, though, the pump was often powered using a small steam engine that ran using the steam produced by the boiler. A means had to be provided, of course, to put the initial charge of water into the boiler(before steam power was available to operate the steam-powered feed water pump).the pump was often a positive displacement pump that had steam valves and cylinders at one end and feed water cylinders at the other end; no crankshaft was required.

In thermal plants, the primary purpose of surface condenser is to condense the exhaust steam from a steam turbine to obtain maximum efficiency and also to convert the turbine exhaust steam into pure water so that it may be reused in the steam generator or boiler as boiler feed water. By condensing the exhaust steam of a turbine at a pressure below atmospheric pressure, the steam pressure drop between the inlet and exhaust of the turbine is increased, which increases the amount heat available for conversion to mechanical power. Most of the heat liberated due to condensation of the exhaust steam is carried away by the cooling medium (water or air) used by the surface condenser.

4. Control valvesControl valves are valves used within industrial plants and elsewhere to control operating conditions such as temperature,pressure,flow,and liquid Level by fully partially opening or closing in response to signals received from controllers that compares a set point to a process variable whose value is provided by sensors that monitor changes in such conditions. The opening or closing of control valves is done by means of electrical, hydraulic or pneumatic systems

7. DeaeratorA Deaerator is a device for air removal and used to remove dissolved gases (an alternate would be the use of water treatment chemicals) from boiler feed water to make it non-corrosive. A deaerator typically includes a vertical domed deaeration section as the deaeration boiler feed water tank. A Steam generating boiler requires that the circulating steam, condensate, and feed water should be devoid of dissolved gases, particularly corrosive ones and dissolved or suspended solids. The gases will give rise to corrosion of the metal. The solids will deposit on the heating surfaces giving rise to localized heating and tube ruptures due to overheating. Under some conditions it may give to stress corrosion cracking.Deaerator level and pressure must be controlled by adjusting control valves- the level by regulating condensate flow and the pressure by regulating steam flow. If operated properly, most deaerator vendors will guarantee that oxygen in the deaerated water will not exceed 7 ppb by weight (0.005 cm3/L)

8. Feed water heaterA Feed water heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feed water reduces the irreversible involved in steam generation and therefore improves the thermodynamic efficiency of the system.[4] This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feed water is introduces back into the steam cycle.In a steam power (usually modeled as a modified Ranking cycle), feed water heaters allow the feed water to be brought up to the saturation temperature very gradually. This minimizes the inevitable irreversibilitys associated with heat transfer to the working fluid (water). A belt conveyor consists of two pulleys, with a continuous loop of material- the conveyor Belt that rotates about them. The pulleys are powered, moving the belt and the material on the belt forward. Conveyor belts are extensively used to transport industrial and agricultural material, such as grain, coal, ores etc.

9. PulverizerA pulverizer is a device for grinding coal for combustion in a furnace in a fossil fuel power plant.

10. Boiler Steam DrumSteam Drums are a regular feature of water tube boilers. It is reservoir of water/steam at the top end of the water tubes in the water-tube boiler. They store the steam generated in the water tubes and act as a phase separator for the steam/water mixture. The difference in densities between hot and cold water helps in the accumulation of the hotter-water/and saturated steam into steam drum. Made from high-grade steel (probably stainless) and its working involves temperatures 390C and pressure well above 350psi (2.4MPa). The separated steam is drawn out from the top section of the drum. Saturated steam is drawn off the top of the drum. The steam will re-enter the furnace in through a super heater, while the saturated water at the bottom of steam drum flows down to the mud-drum /feed water drum by down comer tubes accessories include a safety valve, water level indicator and fuse plug. A steam drum is used in the company of a mud-drum/feed water drum which is located at a lower level. So that it acts as a sump for the sludge or sediments which have a tendency to the bottom.

11. Super HeaterA Super heater 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 condense inside the engine. Super heaters increase the efficiency of the steam engine, and were widely adopted. Steam which has been superheated is logically known assuperheated steam;non-superheated steam is calledsaturated steam or wet steam; Super heaters were applied to steam locomotives in quantity from the early 20th century, to most steam vehicles, and so stationary steam engines including power stations.

12. EconomizersEconomizer is a mechanical device intended to reduce energy consumption, or to perform another useful function like preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, and heating, ventilating and air conditioning. In boilers, economizer are heat exchange devices that heat fluids , usually water, up to but not normally beyond the boiling point of the fluid. Economizers are so named because they can make use of the enthalpy and improving the boilers 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 the fill it (the feed water). Modern day boilers, such as those in cold fired power stations, are still fitted with economizer which is decedents of Greens original design. In this context they are turbines before it is pumped to the boilers. A common application of economizer is steam power plants is to capture the waste hit from boiler stack gases (flue gas) and transfer thus it to the boiler feed water thus lowering the needed energy input , in turn reducing the firing rates to accomplish the rated boiler output . Economizer lower 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.

13. Air PreheaterAir preheater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler). The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the fuel gas. As a consequence, the flue gases are also sent to the flue gas stack (or chimney) at a lower temperature allowing simplified design of the ducting and the flue gas stack. It also allows control over the temperature of gases leaving the stack.

14. PrecipitatorAn Electrostatic precipitator (ESP) or electrostatic air cleaner is a particulate device that removes particles from a flowing gas (such As air) using the force of an induced electrostatic charge. Electrostatic precipitators are highly efficient filtration devices, and can easily remove fine particulate matter such as dust and smoke from the air steam.ESPs continue to be excellent devices for control of many industrial particulate emissions, including smoke from electricity-generating utilities (coal and oil fired), salt cake collection from black liquor boilers in pump mills, and catalyst collection from fluidized bed catalytic crackers from several hundred thousand ACFM in the largest coal-fired boiler application.

The original parallel plate-Weighted wire design (described above) has evolved as more efficient ( and robust) discharge electrode designs were developed, today focusing on rigid discharge electrodes to which many sharpened spikes are attached , maximizing corona production. Transformer rectifier systems apply voltages of 50-100 Kilovolts at relatively high current densities. Modern controls minimize sparking and prevent arcing, avoiding damage to the components. Automatic rapping systems and hopper evacuation systems remove the collected particulate matter while on line allowing ESPs to stay in operation for years at a time.

15. Fuel gas stackA Fuel gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called fuel gases are exhausted to the outside air. Fuel gases are produced when coal, oil, natural gas, wood or any other large combustion device. Fuel gas is usually composed of carbon dioxide (CO2) and water vapor as well as nitrogen and excess oxygen remaining from the intake combustion air. It also contains a small percentage of pollutants such as particulates matter, carbon mono oxide, nitrogen oxides and sulfur oxides. The flue gas stacks are often quite tall, up to 400 meters (1300 feet) or more, so as to disperse the exhaust pollutants over a greater aria and thereby reduce the concentration of the pollutants to the levels required by governmental environmental policies and regulations.When the fuel gases exhausted from stoves, ovens, fireplaces or other small sources within residential abodes, restaurants , hotels or other stacks are referred to as chimneys.

3.2 BOILER MAINTENANCE DIVISION I/II/ (BMD-I/II/)

As the name suggests this unit maintains the boiler and checks out its proper functioning. There are 5 boilers 3 of 95 MW and 2 of 210 MW each. Each boiler is considered as one unit.Structure of units 1,2,3 is same and so is of unit 4,5

Units 1/2/3 (95 MW each)1. I.D Fans2 in no.

2. F.D Fans2 in no.

3. P.A.Fans2 in no.

4. Mill Fans3 in no.

5. Ball mill fans3 in no.

6. RC feeders3 in no.

7. Slag Crushers5 in no.

8. DM Make up Pump2 in no.

9. PC Feeders4 in no.

10. Worm Conveyor1 in no.

11. Turnikets4 in no.

Units 4/5 (210 MW each)1. I.D Fans2 in no.

2. F.D Fans2 in no.

3. P.A Fans2 in no.

4. Bowl Mills6 in no.

5. R.C Feeders6 in no.

6. Clinker Grinder2 in no.

7. Scrapper2 in no.

8. Seal Air Fans2 in no.

9. Hydrazine and Phosphorous Dozing 2 in no.

2/3 in no.

Coal Handling Plant and New Coal Handling Plant (CHP/ NCHP)The old coal handling plant caters to the need of units 2,3,4,5 and 1 whereas the latter supplies coal to units 4 and V.O.C.H.P. supplies coal to second and third stages in the advent coal to usable form to (crushed) form its raw form and send it to bunkers, from where it is send to furnace.

Major Components1. WAGON TIPPLER: -Wagons from the coal yard come to the tippler and are emptied here. The process is performed by a slip ring motor of rating: 55 KW, 415V, 1480 RPM. This motor turns the wagon by 135 degrees and coal falls directly on the conveyor through vibrators. Tippler has raised lower system which enables is to switch off motor when required till is wagon back to its original position. It is titled by weight balancing principle. The motor lowers the hanging balancing weights, which in turn tilts the conveyor. Estimate of the weight of the conveyor is made through hydraulic weighing machine.

2. CONVEYOR: -There are 14 conveyors in the plant. They are numbered so that their function can be easily demarcated. Conveyors are made of rubber and more with a speed of 250-300m/min. Motors employed for conveyors has a capacity of 150 HP. Conveyors have a capacity of carrying coal at the rate of 400 tons per hour. Few conveyors are double belt, this is done for imp. Conveyors so that if a belt develops any problem the process is not stalled. The conveyor belt has a switch after every 25-30 m on both sides so stop the belt in case of emergency. The conveyors are 1m wide, 3 cm thick and made of chemically treated vulcanized rubber. The max angular elevation of conveyor is designed such as never to exceed half of the angle of response and comes out to be around 20 degrees.

3.ZERO SPEED SWITCH:-It is safety device for motors, i.e., if belt is not moving and the motor is on the motor may burn. So to protect this switch checks the speed of the belt and switches off the motor when speed is zero.

4. METAL SEPERATORS: -As the belt takes coal to the crusher, No metal pieces should go along with coal. To achieve this objective, we use metal separators. When coal is dropped to the crusher hoots, the separator drops metal pieces ahead of coal. It has a magnet and a belt and the belt is moving, the pieces are thrown away. The capacity of this device is around 50 kg. .The CHP is supposed to transfer 600 tons of coal/hr, but practically only 300-400 tons coal is transferred.

5. CRUSHER: -Both the plants use TATA crushers powered by BHEL motors. The crusher is of ring type and motor ratings are 400 HP, 606 KV. Crusher is designed to crush the pieces to 20 mm size i.e. practically considered as the optimum size of transfer via conveyor.

6. ROTARY BREAKER: -OCHP employs mesh type of filters and allows particles of 20mm size to go directly to RC bunker, larger particles are sent to crushes. This leads to frequent clogging. NCHP uses a technique that crushes the larger of harder substance like metal impurities easing the load on the magnetic separators.

Milling System1. RC Bunker: -Raw coal is fed directly to these bunkers. These are 3 in no. per boiler. 4 & tons of coal are fed in 1 hr. the depth of bunkers is 10m.

2. RC Feeder: -It transports pre crust coal from raw coal bunker to mill. The quantity of raw coal fed in mill can be controlled by speed control of aviator drive controlling damper and aviator change.

3. Ball Mill: -The ball mill crushes the raw coal to a certain height and then allows it to fall down. Due to impact of ball on coal and attraction as per the particles move over each other as well as over the Armor lines, the coal gets crushed. Large particles are broken by impact and full grinding is done by attraction. The Drying and grinding option takes place simultaneously inside the mill.

4. Classifier: -It is an equipment which serves separation of fine pulverized coal particles medium from coarse medium. The pulverized coal along with the carrying medium strikes the impact plate through the lower part. Large particles are then transferred to the ball mill.

5. Cyclone Separators: -It separates the pulverized coal from carrying medium. The mixture of pulverized coal vapour caters the cyclone separators.

6. Turniket: -It serves to transport pulverized coal from cyclone separators to pulverized coal bunker or to worm conveyors. There are 4 turnikets per boiler.

7. Worm Conveyor: -It is equipment used to distribute the pulverized coal from bunker of one system to bunker of other system. It can be operated in both directions.

8. Mills Fans: -It is of 3 typesSix in all and are running condition all the time.

(a) ID Fans: -Located between electrostatic precipitator and chimney.Type-radicalSpeed-1490 rpmRating-300 KWVoltage-6.6 KVLubrication-by oil(b) FD Fans: - Designedto handle secondary air for boiler. 2 in number and provide ignition of coal.Type-axialSpeed-990 rpmRating-440 KWVoltage-6.6 KV(c) Primary Air Fans: -Designed for handling the atmospheric air up to 50 degrees Celsius, 2 in numbers, and they transfer the powered coal to burners to firing.Type-Double suction radialRating-300 KWVoltage-6.6 KVLubrication-by oilType of operation-continuous 9. Bowl Mill: -One of the most advanced designs of coal pulverizes presently manufactured.Motor specification squirrel cage induction motorRating-340 KWVoltage-6600KVCurreen-41.7ASpeed-980 rpmFrequency-50 HzNo-load current-15-16 A

New Coal Handling Plant (NCHP)

1.Wagon Tippler:-

Motor Specification(i) H.P 75 HP(ii) Voltage 415, 3 phase(iii) Speed 1480 rpm(iv) Frequency 50 Hz(v) Current rating 102 A

2.Coal feed to plant:-

Feeder motor specification(i) Horse power 15 HP(ii) Voltage 415V,3 phase(iii) Speed 1480 rpm(iv) Frequency 50 Hz

3. Conveyors Nomenclature:-10A, 10B/11A, 11B/12A, 12B/13A, 13B/14A, 14B/15A, 15B/16A, 16B/17A, 17B/18A, 18B.

4. Transfer Point 6

5. Breaker House

6. Rejection House

7. Reclaim House

8. Transfer Point 7

9. Crusher House

10. Exit

The coal arrives in wagons via railways and is tippled by the wagon tipplers into the hoppers. If coal is oversized (>400 mm sq) then it is broken manually so that it passes the hopper mesh. From the hopper mesh it is taken to the transfer point TP6 by conveyor 12A ,12B which takes the coal to the breaker house , which renders the coal size to be 100mm sq. the stones which are not able to pass through the 100mm sq of hammer are rejected via conveyors 18A,18B to the rejection house . Extra coal is to sent to the reclaim hopper via conveyor 16. From breaker house coal is taken to the TP7 via Conveyor 13A, 13B. Conveyor 17A, 17B also supplies coal from reclaim hopper, From TP7 coal is taken by conveyors 14A, 14B to crusher house whose function is to render the size of coal to 20mm sq. now the conveyor labors are present whose function is to recognize and remove any stones moving in the conveyors . In crusher before it enters the crusher. After being crushed, if any metal is still present it is taken care of by metal detectors employed in conveyor 10.

3.3 PLANT AUXILIARY MAINTENANCE (PAM)

This unit of the plant mainly dealt with the auxiliary or helping parts in the plant e.g.: water treatment, ash treatment, pump division etc.

This one week of training in this division were divided as follows:

1. Control Structure Pump House (CSPH)2. Water Treatment Plant (WTP)3. Ash Pump House (APH)4. Compressed Air SystemsThe details of the above sub units are as follows: Control Structure Pump House (CSPH)This unit consists of all types of pumps used in plants for purposes like water supply, ash slurry flow etc. The various types of pumps are:

S.NoTypesNo.

1CRW Pump3

2Fire Fighting Pump2

3Diesel Fire Pump1

4Low Pressure Pump3

5High Pressure Pump6

6TWS Pump3

CRW pump is raw water pump used in CSPH, through which raw water is sent into water treatment plant to get demineralised water. Fire Fighting Pumps are used to pacify fire, which occurs most of the time in Coal Handling Plant. These pumps direct the screened or strained water into the areas where fire has started. Diesel Fire Pump is an alternative to Fire fighting pump. It acts as spare. Low Pressure Pump is used to direct treated water into turbines and cooling lines of units 1, 2, 3, 4, 5. In case LP pump is not able to send water up to unit 4 or 5, HP pumps are used. High Pressure Pumps are also used in ash lines, where the ash is directed into slurry pond. Travelling Water Strainer or TWS pump is used to screen the catchable impurities, plastics, dirt through screens placed in the inlet of the Agra canal channel.

Water Treatment Plant (WTP)The raw water from CSPH is sent to WTP where it is processed and converted into DM water. This unit has 8 pumps in all, of which 3 pumps are of 210 MW and are used in running plant, whereas other 5 are 100 MW pumps used in cooling water circulation. Here, initially raw water is mixed with alum and chlorine, and then passed through chambers of carbon filter to convert it to clarified water. This water is passed through resin filter and then mixed with 30 % HCL solution, to form ions. Then it is passed through cation chamber to separate cations, and similarly anions are removed through anion chamber. Thus we get carbonated water, this water is passed through the process of decarbonation, and thus we get DM or Demineralised water. The layout of water treatment plant is shown in the below figure:

Ash Pump House (APH)In the bottom ash system the ash slag discharged from furnace bottom is collected in two water impounded scraper troughs installed below bottom ash hoppers. The ash is continuously transported by means of scrapper chain conveyor, on to the respective clinker grinders which reduces the lump size to required fineness. The crushed ash from clinker grinders falls into the ash sluice trench provided below bottom ash hopper from where ash slurry is further transported to ash slurry sump aided by the ash sluice channel. If the clinker grinder is not in operation , bottom ash can be discharged directly into the sluice channel through bifurcating chute bypass the grinder.The Main types of hoppers used in power plants are: Water Filter Hoppers Quencher Cooled Ash HopperThe various ash disposal systems are: Fly Ash SystemThe fly ash collected in these hoppers drop continuously to flushing apparatus where fly ash gets mixed with flushing water and the resulting slurry drops into the ash sluice channel. Low pressure water is applied through the nozzle directing tangentially to the section of pipe to create turbulence and proper mixing of ash with water. For the maintenance of flushing apparatus plate valve is provided between apparatus and connecting chute. Ash Water SystemHigh pressure water required for B.A. hopper quenching nozzles, B.A. hoppers window spraying, clinker grinder sealing scrapper bars, cleaning nozzles, B.A. hopper seal through flushing, Economizer hoppers flushing nozzles and sluicing trench jetting nozzles is tapped from the high pressure water ring main provided in the plant area.Low pressure water required for bottom ash hopper seal through make up, scrapper conveyor makeup, flushing apparatus jetting nozzles for all. F.A.hoppers excepting economizer hoppers, is tapped from low pressure water ring mains provided in the plant area.

Ash Slurry SystemBottom ash and fly ash slurry of the system is sluiced up to ash slurry pump along the channel with the aid of high pressure water jets located at suitable intervals along the channel.Slurry pump suction line consisting of reducing elbow with drain valve reducer and butterfly valve and portion of slurry pump delivery line consisting of butterfly valve, pipe and fittings has also been provided.

Compressed Air SystemsInstrument air is required for operating various dampers, burner tilting devices, diaphragm valves etc., in the 210 MW units. Station air meets the general requirement of the power station such as light oil atomizing air, for cleaning filters and for various maintenance works. The control air compressors have been housed separately with separate receivers and supply headers and their tappings.Control Air SystemThese have been installed for supplying moisture free dry air required for instrument used. The output from the compressor is fed to air receivers via non return valves. From the receiver air is passed through the dryers to the main instrument air line which runs along with the boiler house and turbine house of 210 MW units.There is one interconnection between service air and instrument air headers just at the inlet of drying units. This connection has been provided as an emergency provision to meet the requirement of instrument air in case of non-availability of instrument air compressor. The line connecting the service air header with instrument air header is provided with two isolating valves, one oil separator, one activated carbon filter, one non return valve and one regulating valve. Oil and dust free air is supplied to the instrument air header which is then passed through air drier units. Instrument air compressors are of double acting horizontal cross head type of two opposed cylinder. The compressors are driven by electric motor through V belts. Gear wheel type lubricating oil pump is provided to feed the main bearing. Connecting rod bearing and cross heads of one side ie. to the opposite side of crank shaft rotation piston. The compressor is equipped with water cooled inter cooler or header, pressure regulator to load and unload the compressor and safety valves for first and second stages. The suction air filter is at the middle of the cylinder so that air can enter at both ends of the piston. After compression the air passes through the delivery valves to the intercooler where the air is cooled and enters the HP cylinder. The entrapped air in HP side is compressed in a similar manner as in LP cylinder to the required pressure and enters the header connected to the HP cylinders through the delivery valves and then finally to the air receiver.Air Drying UnitAir contains moisture which tends to condense, and cause trouble in operation of various devices by compressed air. Therefore drying of air is accepted widely in case of instrument air. Air drying unit consists of dual absorption towers with embedded heaters for reactivation. The absorption towers are adequately filled with specially selected silica gel and activated alumina .While one tower is drying the air, the other tower is under reactivation. Thus the unit maintains continuous supply of dry air for plant requirement. Thus the system is completely automatic.

3.4 POLLUTION CONTROL AND WASTE MANAGEMENTNTPC is committed to theenvironment, generating power at minimal environmental cost and preserving the ecology in the vicinity of the plants. Harmony between man and environment is the essence of healthy life and growth. Therefore, maintenance of ecological balance and a pristine environment has been of utmost importance to NTPC. It has been taking various measures discussed below for mitigation of environment pollution due to power generation.

Pollution Control systems:While deciding the appropriate technology for its projects, NTPC integrates many environmental provisions into the plant design. In order to ensure that NTPC comply with all the stipulated environment norms, various state-of-the-art pollution control systems / devices as discussed below have been installed to control air and water pollution.

Electrostatic Precipitators (ESP):The ash left behind after combustion of coal is arrested in high efficiency Electrostatic Precipitators (ESPs) and particulate emission is controlled well within the stipulated norms. The ash collected in the ESPs is disposed to Ash Ponds in slurry form.Flue Gas Stacks:Tall Flue Gas Stacks have been provided for wide dispersion of the gaseous emissions (SOX, NOX etc) into the atmosphere.

Low-NOX Burners:In gas based NTPC power stations, NOx emissions are controlled by provision of Low-NOx Burners (dry or wet type) and in coal fired stations, by adopting best combustion practices.

Neutralizations Pits:Neutralizations pits have been provided in the Water Treatment Plant (WTP) for pH correction of the effluents before discharge into Effluent Treatment Plant (ETP) for further treatment and use.

Coal Settling Pits / Oil Settling Pits:In these Pits, coal dust and oil are removed from the effluents emanating from the Coal Handling Plant (CHP), coal yard and Fuel Oil Handling areas before discharge into ETP.

DE & DS Systems:Dust Extraction (DE) and Dust Suppression (DS) systems have been installed in all coal fired power stations in NTPC to contain and extract the fugitive dust released in the Coal Handling Plant (CHP).

Cooling Towers:Cooling Towers have been provided for cooling the hot Condenser cooling water in closed cycle Condenser Cooling Water (CCW) Systems. This helps in reduction in thermal pollution and conservation of fresh water.

Ash Dykes & Ash Disposal systems:Ash ponds have been provided at all coal based stations except Dadri where Dry Ash Disposal System has been provided. Ash Ponds have been divided into lagoons and provided with garlanding arrangements for change over of the ash slurry feed points for even filling of the pond and for effective settlement of the ash particles. Ash in slurry form is discharged into the lagoons where ash particles get settled from the slurry and clear effluent water is discharged from the ash pond. The discharged effluents conform to standards specified by CPCB and the same is regularly monitored.At its Dadri Power Station, NTPC has set up a unique system for dry ash collection and disposal facility with Ash Mound formation. This has been envisaged for the first time in Asia which has resulted in progressive development of green belt besides far less requirement of land and less water requirement as compared to the wet ash disposal system.Ash Water Recycling System:Further, in a number of NTPC stations, as a proactive measure, Ash Water Recycling System (AWRS) has been provided. In the AWRS, the effluent from ash pond is circulated back to the station for further ash sluicing to the ash pond. This helps in savings of fresh water requirements for transportation of ash from the plant. The ash water recycling system has already been installed and is in operation at Ramagundam, Simhadri, Rihand, Talcher Kaniha, Talcher Thermal, Kahalgaon, Korba and Vindhyachal. The scheme has helped stations to save huge quantity of fresh water required as make-up water for disposal of ash.

Dry Ash Extraction System (DAES):Dry ash has much higher utilization potential in ash-based products (such as bricks, aerated autoclaved concrete blocks, concrete, Portland pozzolana cement, etc.). DAES has been installed at Unchahar, Dadri, Simhadri, Ramagundam, Singrauli, Kahalgaon, Farakka, Talcher Thermal, Korba, Vindhyachal, Talcher Kaniha and BTPS.

Liquid Waste Treatment Plants & Management System:The objective of industrial liquid effluent treatment plant (ETP) is to discharge lesser and cleaner effluent from the power plants to meet environmental regulations. After primary treatment at the source of their generation, the effluents are sent to the ETP for further treatment. The composite liquid effluent treatment plant has been designed to treat all liquid effluents which originate within the power station e.g. Water Treatment Plant (WTP), Condensate Polishing Unit (CPU) effluent, Coal Handling Plant (CHP) effluent, floor washings, service water drains etc. The scheme involves collection of various effluents and their appropriate treatment centrally and re-circulation of the treated effluent for various plant uses.NTPC has implemented such systems in a number of its power stations such as Ramagundam, Simhadri, Kayamkulam, Singrauli, Rihand, Vindhyachal, Korba, Jhanor Gandhar, Faridabad, Farakka, Kahalgaon and Talcher Kaniha. These plants have helped to control quality and quantity of the effluents discharged from the stations.

Sewage Treatment Plants & Facilities:Sewage Treatment Plants (STPs) sewage treatment facilities have been provided at all NTPC stations to take care of Sewage Effluent from Plant and township areas. In a number of NTPC projects modern type STPs with Clarifloculators, Mechanical Agitators, sludge drying beds, Gas Collection Chambers etc have been provided to improve the effluent quality. The effluent quality is monitored regularly and treated effluent conforming to the prescribed limit is discharged from the station. At several stations, treated effluents of STPs are being used for horticulture purpose.

Waste ManagementVarious types of wastes such as Municipal or domestic wastes, hazardous wastes, Bio-Medical wastes get generated in power plant areas, plant hospital and the townships of projects. The wastes generated are a number of solid and hazardous wastes like used oils & waste oils, grease, lead acid batteries, other lead bearing wastes ,oil & clarifier sludge, used resin, used photo-chemicals, asbestos packing, e-waste, metal scrap, C&I wastes, electrical scrap, empty cylinders (refillable), paper, rubber products, canteen (bio-degradable) wastes, building material wastes, silica gel, glass wool, fused lamps & tubes, fire resistant fluids etc. These wastes fall either under hazardous wastes category or non-hazardous wastes category as per classification given in Government of Indias notification on Hazardous Wastes (Management and Handling) Rules 1989 (as amended on 06.01.2000 & 20.05.2003). Handling and management of these wastes in NTPC stations have been discussed below.

Advanced / Eco-friendly TechnologiesNTPC has gained expertise in operation and management of 200 MW and 500 MW Units installed at different Stations all over the country and is looking ahead for higher capacity Unit sizes with super critical steam parameters for higher efficiencies and for associated environmental gains. At Sipat, higher capacity Units of size of 660 MW and advanced Steam Generators employing super critical steam parameters have already been implemented as a green field project.Higher efficiency Combined Cycle Gas Power Plants are already under operation at all gas-based power projects in NTPC. Advanced clean coal technologies such as Integrated Gasification Combined Cycle (IGCC) have higher efficiencies of the order of 45% as compared to about 38% for conventional plants. NTPC has initiated a techno-economic study under USDOE / USAID for setting up a commercial scale demonstration power plant by using IGCC technology. These plants can use low-grade coals and have higher efficiency as compared to conventional plants.With the massive expansion of power generation, there is also growing awareness among all concerned to keep the pollution under control and preserve the health and quality of the natural environment in the vicinity of the power stations. NTPC is committed to provide affordable and sustainable power in increasingly larger quantity. NTPC is conscious of its role in the national endeavor of mitigating energy poverty, heralding economic prosperity and thereby contributing towards Indias emergence as a major global economy.

4.0 INFERENCE

In these three weeks at BTPS, I gained practical experience and earned quite a lot ofInformation regarding thermal power engineering.The thermal plant consists of various units. All the main plant running equipments weredivided into units, which were further sub divided into more specific units for theirmaintenance and efficient working.For my three week training, I was assigned the work of two units, which were BMD and PAM. These 2 units are explained above in chapter 3, of this report.Boiler and turbine are the most important part of the power plant, without which the powerplant cannot run. This plant produces 705 MW of electricity, with the help of its 5 units. 3units of 95 MW each and 2 units of 210 MW each. The 95 MW units were the first ones to beestablished followed by the 210 MW units in the later years.As for the unit PAM, it is equally important. It takes care of all the auxiliary processes goingon in the plant. It provides water to all the parts of the plant with the help of pumps present inCSPH. Also it produces DM water from raw water by passing it through water treatmentplant. The ash or the waste produced on burning is taken care of, by Ash handling plant. Thecompressed air required in any part of the plant is provided by the unit comprising of thecompressor, also known as compressor house.The fuel used was coal which was pulverized with the help of bowl and ball mills. Thispulverized coal was the fuel burnt in the furnace to produce heat, which then heated the water to superheated steam. This superheated steam was passed into the turbine rotor, thus rotating the turbine shafts. To ensure the quality of steam generated a process named as reheating is taken into account, which increases the dryness fraction of steam or makes it superheated. Thus as the rotor rotates, it also runs the generator, which produces electricity. This electricity is then sent to GT junction (Generator- Transformer), through which the electricity is passed into the switching yard. After which it is distributed into various grids.process. Thus I learned a lot during my training and hope to use this knowledge in the future.

5.0 BIBLIOGRAPHY

NTPC Trainer Manual , By Training Department Senior Student Training Report , NTPC Nalanda Library NTPC slides , By- NTPC training Department

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