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CHAPTER 1 INTRODUCTION 1.1 About NTPC NTPC Limited (also known as National Thermal Power Corporation Limited) is an Indian Central Public Sector Undertaking (CPSU) under the Ministry of Power, Government of India, engaged in the business of generation of electricity and allied activities. It is a co...

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CHAPTER 1

INTRODUCTION 1.1 About NTPC NTPC Limited (also known as National Thermal Power Corporation Limited) is an Indian Central Public Sector Undertaking (CPSU) under the Ministry of Power, Government of India, engaged in the business of generation of electricity and allied activities. It is a company incorporated under the Companies Act 1956 and a "Government Company" within the meaning of the act. The headquarters of the company is situated at New Delhi. NTPC's core business is generation and sale of electricity to state-owned power distribution companies and State Electricity Boards in India. The company also undertakes consultancy and turnkey project contracts that involve engineering, project management, construction management and operation and management of power plants. The company has also ventured into oil and gas exploration and coal mining activities. It is the largest power company in India with an electric power generating capacity of 43,803 MW . Although the company has approx. 18% of the total national capacity it contributes to over 27% of total power generation due to its focus on operating its power plants at higher efficiency levels (approx. 83% against the national PLF rate of 78%). It was founded by Government of India in 1975, which now holds 70% of its equity shares on 13 May 2015. In May 2010, NTPC was conferred Maharatna status by the Union Government of India. It is ranked 424th in in the Forbes Global 2000 for 2014 The company has set a target to have an installed power generating capacity of 1,28,000 MW by the year 2032. The capacity will have a diversified fuel mix comprising 56% coal, 16% Gas, 11% Nuclear and 17% Renewable Energy Sources(RES) including hydro. By 2032, non-fossil fuel based generation apa ity shall ake up early 28% of NTPC‟s portfolio.

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Fig 1.1 - PLF vs Year graph

1.2 Strategies of NTPC

Fig 1.2 – Strategies of NTPC

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1.3 Vision To e the orld’s largest a d est po er produ er, po eri g I dia’s gro th

1.4 Mission De elop a d provide reliable power, related products and services at competitive prices, integrating multiple energy sources with innovative and eco-friendly technologies and contribute to so iety

1.5 Core Values B E C O M M I T T E D

Business Ethics Environmentally & Economically Sustainable Customer Focus Organizational & Professional Pride Mutual Respect & Trust Motivating Self & others Innovation & Speed Total Quality for Excellence Transparent & Respected Organization Enterprising Devoted

1.7 Installed Capacity TABLE 1.1 – Installed Capacity of NTPC Projects No. of Projects

NTPC OWNED COAL GAS/LIQ. FUEL TOTAL OWNED BY JVCs Coal Gas/LIQ. FUEL GRAND TOTAL

Commissioned Capacity (MW)

14 07 21

22,395 3,955 26,350

3 1 25

314 740 27,404

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TABLE 1.2 – Coal Based Plants Coal based

State

1.

Singrauli

Uttar Pradesh

2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Korba Ramagundam Farakka Vindhyachal Rihand Kahalgaon NTCPP TalcherKaniha Unchahar Talcher Thermal Simhadri Tanda

Chhattisgarh Andhra Pradesh West Bengal Madhya Pradesh Uttar Pradesh Bihar Uttar Pradesh Orissa Uttar Pradesh Orissa Andhra Pradesh Uttar Pradesh

2,100 2,600 1,600 3,260 2,000 1,340 840 3,000 1,050 460 1,000 440

Delhi

705 22,395

14. Badarpur Total (Coal)

Commissioned Capacity (MW) 2,000

TABLE 1.3 – Gas Based Plants Gas based

State

Commissioned Capacity (MW)

1

Anta

Rajasthan

413

2

Auraiya

Uttar Pradesh

652

3

Kawas

Gujarat

645

4

Dadri

Uttar Pradesh

817

5

Jhanor-Gandhar

Gujarat

648

6

Rajiv Gandhi CCPP Kayamkulam

Kerala

350

7

Faridabad

Haryana

430

Total (Gas)

3,955

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TABLE 1.4 – Projects Under Implementation Coal / Hydro

State

Fuel

Additional Capacity Under Implementation (MW)

1.

Kahalgaon Stage II (Phase I) (Phase II)

Bihar

Coal

500 500

2.

Sipat (Stage I) (Stage II)

Chhattisgarh

Coal

1980 1000

3.

Barh

Bihar

Coal

1980

4.

Bhilai (Exp. Power Project-JV with SAIL)

Chhattisgarh

Coal

500

5.

Korba (Stage III)

Chhattisgarh

Coal

500

6.

Farakka (Stage III)

West Bengal

Coal

500

7.

NCTPP (Stage II)

Uttar Pradesh

Coal

980

8.

Simhadri (Stage II)

Andhra Pradesh

Coal

1000

9.

Koldam (HEPP)

Himachal Pradesh

Hydro

800

10. Loharinag Pala (HEPP)

Uttarakhand

Hydro

600

11. TapovanVishnugad (HEPP)

Uttarakhand

Hydro

520

Total (Coal + Hydro)

11,360

TABLE 1.5 – Power Plants with Joint Ventures Coal Based

State

Fuel

Commissioned Capacity (MW)

1

Durgapur West Bengal

Coal

120

2

Rourkela Orissa

Coal

120

3

Bhilai

Chhattisgarh

Coal

74

4

RGPPL

Maharastra

Naptha/LNG 740

Total(JV)

1054

Grand Total (Coal + Gas + JV)

27,404

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1.7 Working Principle A coal based powerplant basically works on Rankine Cycle. Steam is produced in boiler is exported in prime mover and is condensed in condenser to be fed into the boiler again. In practice of good number of modifications are affected so as to have heat economy and to increase the thermal efficiency of plant. Many of the impracticalities associated with the Carnot cycle can be eliminated by superheating the steam in the boiler and condensing it completely in the condenser. The cycle that results is the Rankine cycle, which is the ideal cycle for vapor power plants. The ideal Rankine cycle does not involve any internal irreversibility's . 1–2 2–3 3–4 4–5 5–6 6–1

BFP work Heating of water to convert it finally to superheated steam in boiler Expansion in HP turbine Reheating Expansion in IP and LP turbine Cooling in Condenser

Fig 1.3 – Rankine Cycle (with reheat)

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1.8 About NTPC Dadri National Capital Power Station (NCPS) Or NTPC Dadri, is the power project to meet the power demand of National Capital Region (India). It has a huge coal-fired thermal power plant and a gas-fired plant and has a small township located in Uttar Pradesh, India for its employees. NTPC Dadri is a unique power plant of NTPC group which has both coal based thermal plant and gas based thermal plant of 1820 MW and 817 MW respectively and 5 MW solar plant totaling 2642 MW

1.8.1 Installed Capacity Coal based The coal-based station mainly meets power requirements of the National Capital Region [NCR] , and the northern grid . With the World Bank funding component , the capital cost of the units is Rs. 16.69 billion . There are four 210 MW coal based units and two 490MW coal based units. The units have a coal-fired boiler and a steam turbine each . The boiler design is also suitable for 100% operations with heavy furnace oil firing . For this , three storage tanks , each of capacity 15,000 kL , enough for 10 days continuous oil firing requirements have been provided for the boilers . TABLE 1.6 – NTPC Dadri Coal Based Stage

Unit Number

Installed Capacity (MW)

Date of Commissioning

1

210

1991 October

2

210

1992 December

3

210

1993 March

4

210

1994 March

5

490

2010 January

6

490

2010 July

Six

1820

1st

2nd Total

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TABLE 1.7 – NTPC Dadri Gas Based Stage

Unit Number

Installed Capacity (MW)

Date of Commissioning

GT / ST

1

130.19

1992 March

GT

2

130.19

1992 May

GT

3

130.19

1992 June

GT

4

130.19

1992 November

GT

5

154.51

1993 February

ST

6

154.51

1993 March

ST

Six

829.78

1st

Total

Grand Total capacity is 2637 MW.

1.8.2 Location It is located in Gautam Budh Nagar district of Uttar Pradesh about 25 km from Ghaziabad and about 9 km fromDadri. It is nearly 48 km from New Delhi towards Hapur. The township has an area of about 500 acres over all. NTPC Dadri is a branch of National Thermal Power Corporation, which is a public sector now. It is about 20km from Ghaziabad via Badalpur, Mahawar, Bamabawar, and Akilpur Jagir.

1.8.3 Coal Source The coal is transported from the Piparwar block of mines of the North Karanpura Coalfields of Jharkhand , over a distance of about 1,200 kms. , by the Indian Railways bottom discharge , and Box 'N' type of wagons . The coal requirement for the six units is about 25000M.T. each day. The station has its' own 14 kms. Long rail track from the Dadri Railway Statio , to the site, and a 6 km in-plant track, on electric traction.

1.8.4 Water Source Upper Ganga Canal Dehra Headworks, During closure of UGC through network of tube wells. The consumption of cooling water is 50 cusecs (1415.85 litres/sec).

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CHAPTER 2

COAL CYCLE 2.1 Coal Supplied at NTPC Dadri Coal is supplied to NTPC, Dadri by Piparwar coal mines. The type of coal is Bituminous and Semi Bituminous with following specifications: Moisture- less than 8%  Volatile matter-17% to 19%  Ash- 35% - 40%  Calorific Value- 4500 to 5300 Kcal/kg  Coal is received in railway box rakes containing 50-60 wagons in each rake.  Capacity of each box wagon is about 55 ton.  The BOX-N type wagons are placed on 2 wagon tippler (one for Stage-I and other for Stage-II)  The BOBR type wagons are emptied on track hoppers

2.2 Different Components of Coal Cycle          

Wagon Tippler Track Hopper Paddle Feeder Conveyer Belts Crusher House Stacker cum Reclaimer Coal Yard Coal Bunker Coal Feeder Coal Mills  Furnace

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Fig 2.1 – Coal Cycle

2.2.1 Wagon Tippler Wagon from coal yard come to the tippler and emptied here. There are 2 wagon tipplers. The tippler is tilted to about 135° so that coal from the wagon is emptied into the hopper. Elliptics paddle feeders are used to move the coal from hoppers to conveyer belts. In this it takes 52 sec to raise a wagon, 10 sec to empty the wagon completely & then again 52 sec to bring the tippler down. A semicircular huge WT gear is used to run the tippler. Protocol cameras have been installed for safety to ensure that no moving creature or object is near the wagon which is on the tippler.

2.2.2 Track Hopper Coal in BOBR (Box Open Bottom Release) was unloaded on the track hoppers. The track hoppers are shown as follows. The Coal is stored in the hoppers from where it is passed on to the conveyer belts by paddle feeders, towards the crusher house.

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Fig 2.2 – Wagon Tippler

Fig 2.3 – Track Hoppers

2.2.3 Paddle Feeder These are movable elliptical feeders with paddle like structures so as to move the coal from the bottom of the track hoppers to the conveyer belts. There are 4 paddle feeders which can move along the bottom of the track hopper at different positions.

2.2.4 Conveyer Belts 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. Conveyer belts are used in the CHP to transfer coal from one place to other as required in a convenient & safe way. All the belts are numbered accordingly so that their function can be easily demarcated. These belts are made of rubber & move with a speed of 250-300 m/min.

2.2.5 Safety Switches in Conveyers There are certain switches which are used for safe operation of th conveyers used throughout the plant.  Belt Sway Switch These are the switches which are operated when there is sway in the conveyer belt, i.e. the belt move in a particular direction outside its fixed path. These are located on both the sides of the belt. In case there is a sway in the belt, the switch gets activated and stop the conveyer so as to avoid accidents  Pull Cord Switch These are the switches which are installed at every 10m gap in a conveyer belt to ensure the safety of motors running the conveyer belts. If at any time some accident happens or the conveyer belt is needed to be stopped immediately, then the cord is pulled which activates the switch and stops the conveyer. Page | 11

 Zero Speed Switch It is used as a safety device for the motor i.e. when the belt is not moving but the pulley is rotating. This switch checks the speed of the belt & switches off the motor when speed of the belt is zero.

2.2.6 Crusher House After the coal is unloaded in the wagon tipplers and track hopper (size of coal=-250mm), it is conveyed to the crusher house for reducing the size of the coal upto -20mm which is the optimum size for transfer via conveyers. Table 2.1 – Crusher House No. and Make of Crusher Type and Size Main Crusher Capacity Motor Rating Power Supply RPM

8, Pennsylvenia, USA Ring Granulators, TKKGN-48093 875 tonnes/hr 800hp (597KW) . kv, 3Φ, 0Hz 743

Fig 2.4 – Coal Sizes

2.2.7 Stacker cum Reclaimer It is used for stacking (storage) of the excess coal in the coal yards. When there is a requirement of the stored coal, reclaiming process starts and the coal is sent to the coal bunkers through conveyer belts. There are 3 Stacker Reclaimers at NTPC Dadri with stacking capacity of 1400tph and reclaiming capacity of 1400tph with boom conveyer speed of 3m/s

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Fig 2.5 – Stacker cum Reclaimer

2.2.8 Coal Yard Whenever the coal bunkers are filled and there is excess crushed coal in the plant, it is stored in the coal yard.  Capacity - 45 days coal of stagel requirement, 500000m3 of coal approx.  No. of coal piles in stockyard – 6  Length/Height of each pile - 470/10m Water is continuously sprayed on the coal piles so as to settle the coal dust. The water also cools the coal so as to prevent the escape of the volatile material from the coal The coal yards of both the stages are interconnected by conveyers so as to supply coal to the one who is in deficiency of coal at a particular time

2.2.9 Coal Bunker After the coal is crushed in the crusher house, it is either sent to the coal yards or directly to the coal bunkers. These are very large coal storage containers which are placed above the coal mills (where the coal is ground finely). These are cylindrical in shape with conical cum hyperbolic hopper at bottom and made up of 8mm M.S. plate  Stage I – 6 Coal Bunkers per unit  Stage II – 9 Coal Bunkers per Unit

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Fig 2.6 – Coal Bunkers (in Yellow)

2.2.10 Coal Feeder It is situated just below the coal bunkers. It is used to send calculated amount of coal from the coal bunkers to the coal mills as per the requirement of the furnace. The quantity of coal fed is controlled by controlling the speed of the conveyer inside it. Maximum and minimum capacity of the feeder is 60MT/hr and 6MT/hr respectively

2.2.11 Coal Mill The oal ills are situated just elo the ra oal feeders. It’s ai fu tio is to pulverize the coal from -25mm size to 200mesh size. In NTPC Dadri there is a bowl type coal mill in which there is a bowl and three rollers at 120° to each other. The bowl rotates at 50rpm and the rollers rotate about their own axis. The rollers are pressed against the bowl using springs so as to facilitate the grinding of coal. The coal comes in the coal mill from the top from the coal feeder through a single pipe. After the coal is pulverized it is carried by the primary air (which enters the mill from bottom towards the top) to the furnace through 4 pipes. These four pipes carry the coal to the 4 corners of the furnace.

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Table 2.2 – Coal Mill Make No. per boiler Type Capacity Coal size-inlet - outlet Grinding roll material

Fig 2.7 – Coal Mills (Pulveriser)

BHEL 6 XRP 883 49 T/hr 25 mm 70% through 200 mesh Ni -Hard Gr II

Fig 2.8 – Rollers of Coal Mill

2.2.12 FURNACE Furnace is primary part of the boiler where the chemical energy available in the fuel is converted into thermal energy by combustion. Furnace is designed for efficient and complete combustion. Major factors that assist for efficient combustion are the temperature inside the furnace and turbulence, which causes rapid mixing of fuel and air. In modern boilers, watercooled furnaces are used. The boiler fuel firing system is tangentially firing system in which the fuel is introduced from wind nozzle located in the four corners inside the boiler. The crushed coal from the coal crusher is transferred into the unit coalbunkers where the coal is stored for feeding into pulverizing mill through rotary feeder. The rotary feeders feed the coal to pulverize mill at a definite rate. Then coal burners are employed to fire the pulverized coal along with primary air into furnace. These burners are placed in the corners of the furnace Page | 15

and they send horizontal streams of air and fuel tangent to an imaginary circle in the centre of the furnace. Table 2.3 – Furnace specifications Type Bottom Furnace projected area Fuel heat input Residence time for fuel particles in furnace Effective volume used to calculate the residence time Draft Furnace width Furnace depth Furnace height (Ring header to furnace roof) (viii) Furnace volume

Fusion welded walls Dry 3275 m2 519.3 MK Cal/hr 3.14 sec 4200 m3 Balanced 13.868 m 10.592 m 43.136 m 5570 m3

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CHAPTER 3

WATER CYCLE

Fig 3.1 – Water Cycle

3.1 De-Mineralized Water/Steam Cycle  Condensate Cycle  Feed Water Cycle  Steam Cycle

3.2 Condensate Cycle Different Components of Condensate Cycle  Hot Well  Condensate Extraction Pump  Low Pressure Heater  Deaerater  Feed Storage Tank Page | 17

3.2.1 Hot Well After the steam is condensed in the condenser, it gets collected in the hotwell so that the water can be recirculated in the system.

3.2.2 Condensate Extraction Pump This pump is used to extract the condensed water from the hotwell to the deaerater through the low pressure heaters Table 3.1 – Condensate Extraction Pump s...