training report on thermal power plant & thermal power generation by sagar mehta (nashik tps)pdf

A Practical Training Report
Undertaken at
Nashik Thermal Power Station,
Eklahare, MAHAGENCO
Dist. Nashik (Maharashtra)
Submitted in Partial Fulfilment of the Requirement
For the Award of Degree
of
Bachelor of Technology
In Department of Mechanical Engineering
to
Rajasthan Technical University,
Kota
2014-2015
Submitted to: - Submitted by: - Dr. JP Bhamu Sagar Mehta Associate Professor B.Tech. VII Sem Department of Mechanical Engineering 11EEBME753
GOVERNMENT ENGINEERING COLLEGE, BIKANER
August, 2014

ACKNOWLEDGEMENT
It is often said that life is a mixture of achievements, failure, experiences, exposures and efforts to make your dream come true. There are people around you who help you realize your dream. I acquire this opportunity with much pleasure to acknowledge the invaluable assistance of Nasik Thermal Power Station and all the people who have helped me through the course of my journey in successful completion of the summer training.
I would like to take this opportunity to thank all those who have contributed in this report directly or indirectly. I offer my thanks to Mr. Santosh Kulkarni (Dy. Executive Engineer), Mr. N.M. Shinde (Dy.Chief Engineer), Mr. K.M. Mane (Superintendent Engineer), Mr. Kimbahune Vikrant V. (Power User, EAM), and O.R.Usrete (Sr. Chemist) for providing whole hearted Co-operation.
I would personally like to my thank Mr. A.P. Netke (Assistant Engineer and Training In- charge) for helping me throughout my training.
I feel deep sense of gratitude towards Dr. JP Bhamu, Associate Professor in Govt. Engineering College Bikaner, being a constant source of motivation and guidance. I also like to thank all Faculty and all staff members of mechanical department of Govt. Engineering College Bikaner.
I want to thank to all Staff and Workers of NTPS for their guidance and co-operation at each & every step of my training.
I also acknowledge thank to my fellow students for discussing various points during the course of training which proved very useful in preparing this report. I am grateful to my friends who gave me the moral support in my times of difficulties. Last but not the least I would like to express my special thanks to my family for their continuous motivation and support.
Sagar Mehta
11EEBME753

Table of Contents
S. No. Topics Page No.
1 HISTORY OF POWER SECTOR 1
1.1 Introduction 1
1.2 Market Reform 2 2 HISTORY OF INDIAN POWER SECTOR 3 2.1 Introduction 3 2.2 Present Energy Scenario In India 4 3 HISTORY OF THERMAL POWER GENERATION 6 3.1 Introduction 6 3.2 Thermal Power Generation In India 6 4 NASIK THERMAL POWER STATION 7
4.1 Introduction 7
4.2 Installed Capacity 8
4.3 Transport 9
4.4 Shaktiman A Symbol Of Visionary Resourcefulness 9
5 STEAM POWER PLANT 10 5.1 Power Plant 10 5.2 Steam Power Plant 10 5.3 Rankine or Steam Cycle 11 6 THERMAL POWER STATION VIEWS 13
7 POWER PLANT WATER INTAKE 14
7.1 Introduction 14
7.2 Methodology 14
8 COAL HANDLING PLANT 15
8.1 Introduction 15

12 TURBINE OPERATION, MAINTAINANCE AND 31
ITS AUXILIARIES
12.1 Introduction 31
12.2 Working Principle of Steam Turbine 31
12.3 Types of Steam Turbine 31
12.4 Construction and Steam Flow 31
12.5 Valves 32
12.6 Turbine Governing System 32
12.7 Oil Supply System 33
12.8 Turbine Monitoring System 33
12.9 Fixed Points 33
12.10 Steam Turbine starts up 36
12.11 Precautions during Running 36
8.2 Coal 15
8.3 Types of Coal 15
8.4 Coal in India 16
8.5 General Working of CHP 16 9 WATER TREATMENT PLANT 18
9.1 Introduction 18
9.2 Water Treatment Process 18
10 BOILER WATER MONITORING 21
11 BOILER OPERATION, MAINTAINANCE AND 22
ITS AUXILIARIES
11.2 Boiler Main Process 22
11.3 Types of Boiler Used in Power Plant 22
11.4 Boiler Main Auxiliaries 24
11.5 Improving Boiler and Overall Efficiency of Plant 27
11.6 Flue Gas Path 27
11.7 Boiler Auxiliaries Specifications 29

12.12 Materials for Steam Turbine Design 36
13 GENERATOR 37
13.2 Principle of Generation 37
14 STEAM CONDESING SYSTEM 39
14.2 Steam Condensing System Components 39
15 BOILER FEED WATER PUMP 43
15.2 Construction and Operation 43
16 ASH HANDLING PLANT 44
16.2 Types of Coal Ash 44
16.3 Bottom Ash System 45
16.4 Fly Ash System 45
16.5 Areas of Fly Ash Utilization 45
17 ENERGY CONSERVATION AND ENERGY AUDIT 48
17.1 Energy Conservation 48
17.2 Audit 48
18 CONCLUSION 49
19 SUGGESTIONS 50

List of Figures and Tables
S. No. Figure Name Page No. 1 2.1 India’s Installed Capacity by Source 4 2 2.3 Indian Generation Capacity (in MW) 5 3 2.3 India’s GDP Variation with Energy Consumption 5 4 4.1 Nashik Thermal Power Station 9 5 5.1 Rankine or Steam Cycle 11 6 5.2 T-s Diagram of Modified Rankine (Reheat) Cycle 12
7 5.3 Energy Conversion in TPS 12
8 6.1 Plant Layout 13
9 6.2 Typical View of Thermal Power Plant 13 10 8.1 Constituents of Coal 15 11 8.2 Coal Handling Plant 16 12 9.1 Pre-Treatment Plant Flow Diagram 19 13 9.2 Softening Plant Flow Diagram 19 14 11.1 Tangential Fired Boiler 23 15 11.2 Balance Draft Boiler 23 16 11.3 Coal and Flue Gas Cycle 26 17 12.1 Steam Turbine and Regenerative Heating 33 18 12.2 Steam Turbine Rotor 33 19 13.1 Turbo-Generator 36

20 13.2 Generator Transformer 36 21 14.1 Diagram of Typical Water Cooled Condenser 40 22 16.1 Electrostatic Precipitator 46 23 16.2 Typical View of Ash Handling Plant 47 Table Name 24 4.1 Capacity of Units 8 25 8.1 Coal Mill Technical Specifications 17 26 8.2 Coal Feeder Technical Specifications 17 27 9.1 Boiler Water Parameters 20 28 11.1 Boiler Technical Specifications 23 29 11.2 Boiler Parameters 24 30 11.3 Required Boiler Auxiliaries 25 31 11.4 Flue Gas Parameters at Various Stages 28 32 11.5 Materials for Boiler Tubes 29 33 11.6 ID Fan Technical Specifications 29 34 11.7 PA Fan Technical Specifications 29 35 11.8 FD Fan Technical Specifications 30 36 11.9 Air Pre-Heater Technical Specifications 30 37 12.1 Turbine Technical Specifications 34 38 12.2 Oil Pump Technical Specifications 34 39 14.1 Condenser Technical Specifications 42 40 15.1 BFP Technical Specifications 43

ABSTRACT A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different fuel sources. Some prefer to use the term energy centre because such facilities convert forms of heat energy into electricity. Some thermal power plants also deliver heat energy for industrial purposes, for district heating, or for desalination of water as well as delivering electrical power. A large part of human CO2 emissions comes from fossil fuelled thermal power plants; efforts to reduce these outputs are various and widespread. At present 54.09% or 93918.38 MW (Data Source CEA, as on 31/03/2011) of total electricity production in India is from Coal Based Thermal Power Station. A coal based thermal power plant converts the chemical energy of the coal into electrical energy. This is achieved by raising the steam in the boilers, expanding it through the turbine and coupling the turbines to the generators which converts mechanical energy into electrical energy.

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CHAPTER 1 HISTORY OF POWER SECTOR 1.1 INTRODUCTION: - The electric power industry provides the production and delivery of electric energy, often known as power, or electricity, in sufficient quantities to areas that need electricity through a grid connection. The grid distributes electrical energy to customers. Electric power is generated by central power stations or by distributed generation. Although electricity had been known to be produced as a result of the chemical reactions that take place in an electrolytic cell since Alessandro Volta developed the voltaic pile in 1800, its production by this means was, and still is, expensive. In 1831, Faraday devised a machine that generated electricity from rotary motion, but it took almost 50 years for the technology to reach a commercially viable stage. In 1878, in the US, Thomas Edison developed and sold a commercially viable replacement for gas lighting and heating using locally generated and distributed direct current electricity. Additionally, Robert Hammond, in December 1881, demonstrated the new electric light in the Sussex town of Brighton in the UK for a trial period. In early 1882, Edison opened the world’s first steam-powered electricity generating station at Holborn Viaduct in London, where he had entered into an agreement with the City Corporation for a period of three months to provide street lighting. In time he had supplied a number of local consumers with electric light. The method of supply was direct current (DC). It was later on in the year in September 1882 that Edison opened the Pearl Street Power Station in New York City and again it was a DC supply. It was for this reason that the generation was close to or on the consumer's premises as Edison had no means of voltage conversion. The voltage chosen for any electrical system is a compromise. Increasing the voltage reduces the current and therefore reduces the required wire thickness. Unfortunately it also increases the danger from direct contact and increases the required insulation thickness. Furthermore some load types were difficult or impossible to make work with higher voltages. The overall effect was that Edison's system required power stations to

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be within a mile of the consumers. While this could work in city centres, it would be unable to economically supply suburbs with power. The mid to late 1880's saw the introduction of alternating current (AC) systems in Europe and the U.S. AC power had an advantage in that transformers, installed at power stations, could be used to raise the voltage from the generators, and transformers at local substations could reduce voltage to supply loads. Increasing the voltage reduced the current in the transmission and distribution lines and hence the size of conductors and distribution losses. This made it more economical to distribute power over very long distances. Generators (such as hydroelectric sites) could be located far from the loads. AC and DC competed for a while, during a period called the War of Currents. The DC system was able to claim slightly greater safety, but this difference was not great enough to overwhelm the enormous technical and economic advantages of alternating current which eventually won out.
1.2 MARKET REFORM: - There has been a movement towards separating the monopoly parts of the industry, such as transmission and distribution sectors from the contestable sectors of generation and retailing across the world. This has occurred prominently since the reform of the electricity supply industry in England and Wales in 1990. In some countries, wholesale electricity markets operate, with generators and retailers trading electricity in a similar manner to share and accuracy.

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CHAPTER 2 HISTORY OF INDIAN POWER SECTOR
2.1 INTRODUCTION: - The Indian Power Industry before independence was controlled firmly by the British. The first demonstration of electric light in Calcutta was conducted on 24 July 1879 by P W Fleury & Co. On 7 January 1897, Kilburn & Co secured the Calcutta electric lighting license as agents of the Indian Electric Co, which was registered in London on 15 January 1897. A month later, the company was renamed the Calcutta Electric Supply Corporation. The control of the company was transferred from London to Calcutta only in 1970. Enthused by the success of electricity in Calcutta, power was thereafter introduced in Bombay. Mumbai saw electric lighting demonstration for the first time in 1882 at Crawford Market, and Bombay Electric Supply & Tramways Company (B.E.S.T.) set up a generating station in 1905 to provide electricity for the tramway. The first hydroelectric installation in India was installed near a tea estate at Sidrapong for the Darjeeling Municipality in 1897. The first electric train ran between Bombay's Victoria Terminus and Kurla along the Harbour Line, in 1925. In 1931, electrification of the metre gauge track between Madras Beach and Tambaram was started. The power sector in India has undergone significant progress after Independence. When India became independent in 1947, the country had a power generating capacity of 1,362 MW. Hydro power and coal based thermal power have been the main sources of generating electricity. Generation and distribution of electrical power was carried out primarily by private utility companies. Notable amongst them and still in existence is Calcutta Electric. Power was available only in a few urban centres; rural areas and villages did not have electricity. After 1947, all new power generation, transmission and distribution in the rural sector and the urban centres (which was not served by private utilities) came under the purview of State and Central government agencies. State Electricity Boards (SEBs) were formed in all the states. Nuclear power development is at slower pace, which was introduced, in late sixties. The concept of operating power systems on a regional basis crossing the political boundaries of states was introduced in the early sixties. In spite of the overall

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development that has taken place, the power supply industry has been under constant pressure to bridge the gap between supply and demand.
2.2 PRESENT ENERGY SCENARIO IN INDIA: -  The electricity sector in India had an installed capacity of 205.34 Gigawatt (GW) as of June 2013, the world's fifth largest.  Thermal power plants constitute 70% of the installed capacity, hydroelectric about 15% and rest being a combination of wind, small hydro, biomass, waste-to- electricity, and nuclear.  India generated 855 BU (855 000 MU i.e. 855 TW) electricity during 2011-12 fiscal.
Fig. 2.1 India’s Installed Capacity by Source  In terms of fuel, coal-fired plants account for 56% of India's installed electricity capacity, compared to South Africa's 92%; China's 77%; and Australia's 76%. After coal, renewal hydropower accounts for 19%, renewable energy for 12% and natural gas for about 9%.

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Fig. 2.2 Indian Generation Capacity (in MW)
 As of January 2012, one report found the per capita total consumption in India to be 778 kWh.  India is the world's fourth largest energy consumer after United States, China and Russia.
Fig. 2.3 India’s GDP Variation with Energy Consumption

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CHAPTER 3
HISTORY OF THERMAL POWER GENERATION
3.1 INTRODUCTION: - Almost all coal, nuclear, geothermal, solar thermal electric, and waste incineration plants, as well as many natural gas power plants are thermal. The initially developed reciprocating steam engine has been used to produce mechanical power since the 18th Century, with notable improvements being made by James Watt. When the first commercially developed central electrical power stations were established in 1882 at Pearl Street Station in New York and Holborn Viaduct power station in London, reciprocating steam engines were used. The development of the steam turbine in 1884 provided larger and more efficient machine designs for central generating stations. By 1892 the turbine was considered a better alternative to reciprocating engines; turbines offered higher speeds, more compact machinery, and stable speed regulation allowing for parallel synchronous operation of generators on a common bus. After about 1905, turbines entirely replaced reciprocating engines in large central power stations. 3.2 THERMAL POWER GENERATION IN INDIA: -
 Thermal power plants convert energy rich fuel into electricity and heat. Possible fuels include coal, natural gas, petroleum products, agricultural waste and domestic trash / waste.
 Coal and lignite accounted for about 70% of India's installed capacity.
 India's electricity sector consumes about 80% of the coal produced in the country. A large part of Indian coal reserve is similar to Gondwana coal.
 The installed capacity of Thermal Power in India, as of June 30, 2011, was 115649.48 MW which is 65.34% of total installed capacity.
 The state of Maharashtra is the largest producer of thermal power in the country.

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CHAPTER 4
NASIK THERMAL POWER STATION
4.1 INTRODUCTION: - Nashik Thermal Power Plant is located at Eklahare village near Nashik in Maharashtra. The power plant is one of the coal based power plants of Mahagenco (Maharashtra State Power Generation Company Limited – MSPGCL). Mahagenco has the highest overall generation capacity and the highest thermal installed capacity amongst all the state power generation utilities in India. In terms of installed capacity, it is the second highest generation company after NTPC. Nasik Thermal Power Station comprises of 2x140 MW and 3x210 MW units. The first 140 MW unit was synchronized on 16thAugust 1970 followed by second unit on 21st of March 1971.The cost of unit including civil work was Rs. 56.5 crores each.
Boilers are front fired type from Babcock Wilcock France. Turbines are also from France.
NTPS Stage-II comprises of three units of 210 MW each of BHEL Make. The first 210 MW units were synchronized on 26th April 1979 at total project cost of Rs. 94.73 crores. The next two units i.e. Unit No. 4 and 5 of 210 MW were constructed at the cost of Rs. 143.95 crores and commissioned on 10th July 1980 and 30thJanuary 1981 respectively. Thus total cost of Stage-II is Rs. 238.68 crores.
Boilers are corner fired of American design. Turbines are of Russian design.
The power station campus include self contained township with all amenities. The entire complex measures 472 hectare of land on the bank of river Godavari.
The power station with its auxiliary equipment comprise intake pump house on the bank of river Godavari, a large raw water reservoir divided in two halves, and reservoir pump house, Water Treatment Plant for clarified and filter water, cooling towers with canals and CW pump houses and the power station proper with concrete stack, dust collecting plant, boiler plant, steel building housing the plant and equipment in bunker bay, heater bay, and turbine bay. Beyond the turbine bay is the outdoor installation of generator transformers, auxiliary reserve and unit transformers.
About 100 meters away from the powerhouse stack and further beyond are the installations for fuel oil day storage and pump houses and bulk storages with pump house. Near the power

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station is the coal storage yard and coal handling plant, comprising crusher house, surge and reclaim hoppers, wagon tipplers, connecting belt conveyor system with inclined belt conveyors leading to the power station.
NTPS… a major driving force since 1971 pouring 910 MW and an apex of Golden triangle of Mumbai, Pune & Nashik. Industrial house of giants like Mahindra, MICO, VIP, Siemens, Gabriel, CEAT, Raymond, Crompton Greaves, HAL(Hindustan Aeronautics Limited), Security Press are HT Consumers more than110 MW. The power plant has got ISO Certification on April 2002.
4.2 INSTALLED CAPACITY: -
Nashik Thermal Power Station has an installed capacity of 890 MW. The plant has 5 units under operation. The individual units have the generating capacity as follows.
Stage Unit Number Installed Capacity (MW) Date of Commissioning Status Stage I 1 140 August, 1970 Stopped(under renovation) Stage I 2 140 March, 1971 Stopped(under renovation) Stage II 3 210 April, 1979 Running Stage II 4 210 July, 1980 Running Stage II 5 210 January, 1981 Running
Table 4.1 Capacity of Units

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4.3 TRANSPORT: - It is on the Bhusawal-Kalyan section of Central Railway. Coal-based thermal power stations consume large quantities of coal. For example, the Nasik Thermal Power Station consumed 4,626,000 tonnes of coal in 2006-07. Around 80 per cent of the domestic coal supplies in India are meant for coal based thermal power plants and coal transportation forms 42 per cent of the total freight earnings of Indian railways.
4.4 SHAKTIMAN A SYMBOL OF VISIONARY RESOURCEFULNESS: -
NTPS built a scrap metal sculpture "SHAKTIMAN”, weighing 27 tones, 17 meter tall one of its kinds in ASEA recorded in the GUINNES book of records. No doubt it’s a symbol of innovative idea emerged in word and sprit, inspiring visitors that wealth from waste can be a reality.
Fig. 4.1 Shaktiman Statue in Guinness Book of World Records In 1991

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CHAPTER 5
STEAM POWER PLANT
5.1 POWER PLANT: - A power station (also referred to as generating station, power plant, powerhouse, generating plant) is an industrial facility for the generation of electric power.
Types of energy available for generation of electrical energy are follows.
1. Thermal Energy
2. Solar Energy
3. Atomic Energy
4. Hydro Power
5. Wind Power
6. Tidal Power
7. Geo-Thermal
8. From Gas
5.2 STEAM POWER PLANT: - A steam-electric power station is a power station in which the electric generator is steam driven. Water is heated, turns into steam and spins a steam turbine. After it passes through the turbine, the steam is condensed in a condenser. The greatest variation in the design of steam-electric power plants is due to the different fuel sources.
For a steam power plant, practical thermal cycle was suggested by Rankine called Ideal cycle or Rankine cycle. A steam power plant continuously convert the energy stored in fossil fuels (Coal, Oil, Natural Gas) or fissile fuels (Uranium, Thorium) into shaft power into shaft work and ultimately into electricity. The working fluid is water, which is sometimes in liquid phase and sometimes in the vapour phase during its cycle of operations. Figure below illustrate a fossil-fuelled power plant as a bulk energy converter from fuel to electricity using water as working medium. Energy released by burning of fuel is transferred to water by boiler (B) to generate steam at a high pressure and temperature, which expands in the turbine (T) to a low pressure to produced shaft work. The steam leaving the turbine condensed into water in the condenser (C) where cooling water from river or sea circulates carrying away the heat

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released during condensation. The water (condensate) is then fed back to the boiler by the pump (P), and the cycle goes on repeating itself.
5.3 THERMAL POWER STATION WORKS ON ‘RANKINE CYCLE’
Main Components of TPS
1. Boiler
2. Turbine
3. Condenser
4. Boiler feed pump
5. Generator
Fig. 5.1 Rankine or Steam Cycle

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Fig. 5.2 T-s Diagram of Modified Rankine (Reheat) Cycle
Fig. 5.3 Energy Conversion in TPS
Furnace Chemical to Heat
Boiler
Heat energy converts water to saturated Steam
Turbine
Heat energy into Kinetic Energy
Turbine
Kinetic energy into Mechanical Work
Generator Mechanical to Electrical Energy

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CHAPTER 6
THERMAL POWER STATION VIEWS
Fig. 6.1 Plant Layout
Fig. 6.2 Typical View of Thermal Power Plant

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CHAPTER 7
POWER PLANT WATER INTAKE
7.1 INTRODUCTION: -
A systematic study has been carried out to assess the water quality at downstream of Godavari river at Nashik city and its impact on Nashik Thermal Power Station, Eklahare. Water samples from six sampling stations were collected monthly, during period March 08 – April 09 and physic-chemical and chemical parameters were analyzed by the standard methods. The pollution level over a period of time is increasing on the river water mainly due to sewage, industrial and other wastewaters are directly discharge in the river. The use of Godavari river water is, mainly for domestic, industrial, agricultural purpose and huge amount of water is also utilized by Nashik Thermal Power Station for electricity generation.
The intake water lifted by Nashik Thermal Power Station is from downstream of the Godavari River i.e. after Gangawadi. For treatment of such contaminated water huge chemicals are required for production of filtered water (sump water), which leading to high chemical cost. To overcome from these difficulties due to polluted water, the quality assessment of intake water of Nashik Thermal Power Station is necessary for cost effective generation.
7.2 METHODOLOGY: -
The pumping station consists of a box open on the riverside. Two, equally spaced pillar walls at the inside base of the box dived the river approach into three equal bay. Trash racks are provided at the entry of each bay to arrest the floating debris coming with river water. Due to shifting flow of river water bunds with the help of sand bags are sometimes used to diver the flow of river water along the pump house. Sand also accumulates in front of pump house. A dredging arrangement is there to remove the sand from front of the Pump House.
There are four vertical mixed flow type water pumps. These are placed in line in a common basin behind three partitioned bays. All the pumps are motor driven. Motor operated, butterfly types discharge valves are provided for the pumps.

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CHAPTER 8
COAL HANDLING PLANT
8.1 INTRODUCTION: -
In thermal power plant coal is a principal fuel, hence design & layout of coal handling plant is important.
8.2 COAL: -
 Coal is a non renewable solid fuel formed by a series of geochemical process from the plant remains accumulated together with other sediments.
 For calculating usefulness of coal as a fuel it is analyzed by two types
i. Proximate Analysis: Determines moisture, ash, volatile matter and fixed carbon percentage
ii. Ultimate Analysis: Determines carbon, hydrogen, nitrogen, sulfur and oxygen within coal.
Main constituents of coal are
ffffffigFf
Fig. 8.1 Constituents of Coal
8.3 TYPES OF COAL: - According to quality (carbon content), the coal may be divided into following classes:

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i. Anthracite: - It is the best quality coal and its carbon content is as much as 92% with a low volatile matter and very little moisture. It is hard and heavy and burns with great heat. ii. Bituminous: - It is also of good quality coal next to Anthracite. Its carbon content is up to 85%. Coal mined in India, is mainly of bituminous type of Gondwana age. iii. Sub-bituminous: -It is a type of coal whose properties range from those of lignite to those of bituminous coal and are used primarily as fuel for steam-electric power generation. Sub-bituminous coals may be dull, dark brown to black, soft. They contain 15-30% inherent moisture by weight and are non-coking. iv. Lignite: - It is inferior quality coal, full of moisture and volatile matter. Its carbon content is less than 50%. It is also known as ‘brown coal’. v. Peat: - It is the first stage in the formation of coal. It is light and woody and has poor heating capacity. 8.4 COAL IN INDIA: -
The common coals used in Indian industry are bituminous and sub-bituminous coal. The calorific value of Indian coal ranges from 4000-5000 Kcal/kg. Apart from low calorific value, Indian coal suffers from high ash content (15-45%) which is about 30-40%.The good thing about Indian coal is its low sulphur content. 8.5 GENRAL WORKING OF CHP
Fig. 8.2 Coal Handling Plant

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Coal Mill: - A pulveriser or grinder is a mechanical device for the grinding of many different types of materials. For example, a pulveriser mill (Coal Mill) is used to produce pulverize coal for combustion in the steam generating furnaces of fossil fuel power plants.
Types of Coal Mills
i. Bowl Mill (Medium Speed)
ii. Ball & Race Mill (Medium Speed)
iii. Ball and Tube Mill (Low Speed)
TECHNICAL SPECIFICATIONS OF COAL MILL AND COAL FEEDER:-
Coal Mill
MAKE
BHEL
MAKE
BHEL
CAPACITY
31.4 T/HR
CAPACITY
320 KW
TYPE
XRP 763 BOWL MILLS
VOLTAGE
6.6 KV
HRDGROOVE IN
72 % ( 200 MESH)
CURRENT
37 AMP
MILL OUTLET T
80-85 ºC
SPEED
990 RPM
Table 8.1 Coal Mill Technical Specifications
Coal Feeder
MAKE
MITSUBHISHI
SPEED
1430 RPM
TYPE
PIV ROTARY COAL FEEDER
CURRENT
7.6 AMP
CAPACITY
3.7 KW
VOLTAGE
415 V
Table 8.2 Coal Feeder Technical Specifications

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CHAPTER 9
WATER TREATMENT PLANT
9.1 INTRODUCTION: -
Nashik Thermal Power Station is situated at the bank of Godavari River at Eklahare Village. Godavari River is the only source of raw water for Nashik Thermal Power Station for Electricity Generation and other purpose. Raw water quality at Nashik TPS is much typical and contaminated due to release of raw sewage, untreated effluents from various Chemical Industries, various domestic effluents etc. from up-stream. Most of the period during the year, the water contains impurities beyond removal by way of existing conventional system. Due to deteriorated Godavari river water quality, separate arrangement of Darna River water for drinking purpose is made for NTPS colony residents.
9.2 WATER TREATMENT PROCESS: -
i. River water contains a lot of impurities such as algae, fungi, dead vegetation and mineral matter in the form of dissolved solids.
ii. This water is fed after treatment to boiler water system, cooling water system and for domestic purpose.
The treatment is done in two stages –
i. First Stage: - Pre-treatment
Maximum impurities except total dissolved solids and colloidal silica are removed in this treatment.
ii. Second Stage: - Post Treatment
a) Demineralization: - Perfectly pure water is produced by ion exchange process by passing the filtered water through the resins. This water is fed to the boiler feed water system.
b) Softening: - Hardness causing elements such as Calcium and Magnesium are removed in this process. This water is used for cooling water system.
c) Domestic water: - Chlorination / Bleaching Powder dosing is arranged to the filtered water so as to make it suitable for drinking purpose.
Average Incoming River water Parameters are –

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TH – Min – 90 ppm Max – 350 ppm
TCl – Min – 20 ppm Max – 250 ppm
Details of above treatment processes is as under-
Pretreatment Plant: -
i. River water is taken at river water inlet chamber at W. T. Plant where the chemicals
such as alum, lime /bleaching powder, PAC etc. are added.
ii. In this process flocks are formed due to addition of alum / lime which are removed in
settling tank / clarifier.
Fig. 9.1 Pre-Treatment Plant Flow Diagram
Softening Plant: -
Water is passed through base exchangers where hardness causing elements i.e. calcium and
magnesium are removed to get soft water.
Fig. 9.2 Softening Plant Flow Diagram
R – Na + Ca / Mg = R – Ca / Mg + Na
Resin Hard Water Soft Water
Regeneration of Base Exchanger resin is done by using Common Salt, Reaction of which is –
R- Ca / Mg + NaCl = R – Na + Ca / Mg
Salt Resin Effluent
Demineralization: -
Minerals are removed from the filtered water by ion exchange process. Cations (positive
ions) and Anions (Negative ions) are removed from the water one by one using Resin which
FILTERED FILTERED BASE
WATER WATER EXCHANGER SOFT C. T.
SUMP PUMP WATER POND
RIVER Alum,Lime SETTLING RAPID FILTERED
WATER KmnO4 TANK(STG-1) SAND WATER
INTAKE PAC,Bleaching CLARIFIER GRAVITY SUMP
CHAMBER Powder (STG-2) FILTER
RIVER
PUMP

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is an organic material having the capacity to exchange ions in the water with the active group on the resin.
Chemical reactions in Regular Process are
i. Reaction in Cation Exchanger-
Na Cl Na Cl
Ca CO3 + R – H = R ---Ca + H --- CO3
Mg SiO3 Resin Mg SiO3
ii. Reaction in Anion Exchanger-
Cl Cl
H--- SO4 + R – OH = R--- SO4 + OH - H / H2O
SiO3 Resin SiO3
Chemical reactions during Regeneration Process are
i. Reaction in Cation Exchanger-
Na Na Cl
R ---Ca + HCl = R-H + Ca Cl2
Mg Mg Cl2
ii. Reaction in Anion Exchanger-
Cl Cl
R ---SO4 + NaOH = ROH + Na--- SO4
SiO3 SiO3
Recommended Boiler water parameters – Stage – II (210 MW)
Table 9.1 Boiler Water Parameters
Drum Operating Pressure Kg / cm2 126 – 165
M/S BHEL
Recommendation
Parameters at NTPS
Treatment Type
Phosphate
Phosphate
pH at 25 0 C
9.4 - 9.7
9.4 to 9.6
Conductivity at 25 0 C  mhos/cm
100
< 35

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CHAPTER 10
BOILER WATER MONITERING
i. D. M. water which is produced for feeding to boiler water system is having pH 7.0 and Conductivity less than 1.0 micromhos / cm, Silica - NIL.
ii. This water is very sensitive and atmospheric CO2 gets immediately mixed with it to make it acidic which is not desirable, so chemical dosing is done in boiler feed water.
iii. Dissolved oxygen is also present in the D.M. water which is responsible for corrosion. 85 % of dissolved oxygen is removed in deaerator in feed water system.
iv. Hydrazine dosing is arranged through L.P dosing pump at BFP suction for scavenging residual dissolved oxygen in the system water to avoid corrosion of metal surface.
v. pH of D. M. make up water at condenser is about 6.8 to 6.9 ( which is not desirable ) is increased to about 8.8 by dosing Ammonia solution along with Hydrazine through L.P. dosing pump.
vi. Colloidal Silica (which is not removed in D.M. Plant) gets transformed to active silica at Temp. Above 250 deg. Cent. And it appears in boiler drum water.
vii. Silica in the form of silicates is hazardous in boiler water as it gets evaporated to steam and gets deposited directly on the turbine blades as too hard deposits.
CONCLUSION: -
i. The rotation of water is decided by the Govt. as per the agricultural requirement.
ii. Normally the water cycle is about 10 days per month throughout the year.
iii. Due to these reasons, water gets contaminated for about 200 days per year.
iv. Such type of contaminated water has to be treated in W.T. Plant before its utilization for electricity generation.
v. Nashik TPS is situated on the downstream of Godavari River and all the waste water effluents from Nashik City, Nashik Road area, chemical effluent released from MIDC Industries etc. gets mixed with the Godavari River which lastly comes to NTPS Dam.

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CHAPTER 11
BOILER OPERATION, MAINTAINANCE AND ITS AUXILIARIES
11.1 INTRODUCTION: - Steam boiler or simply a boiler is basically a closed vessel into which water is heated until the water is converted into steam at required pressure. The utility boilers are large capacity steam generators used purely for the electrical power generation. In boiler heat energy is released from the combustion of fossils fuel and heat is transferred to different fluids in the system and a part of it is lost or left out as unutilized. The basic working principle of boiler is very simple and easy to understand. The boiler is essentially a closed vessel inside which water is stored. Fuel (generally coal) is bunt in a furnace and hot gasses are produced. These hot gasses come in contact with water vessel where the heat of these hot gases transfer to the water and consequently steam is produced in the boiler. Then this steam is piped to the turbine of thermal power plant. There are many different types of boiler utilized for different purposes like running a production unit, sanitizing some area, sterilizing equipment, to warm up the surroundings etc.
11.2 BOILER MAIN PROCESS: -
i. Send DM water to the boiler through boiler drum to boiler tubes.
ii. Sending fuel (furnace oil and coal) to the boiler through dampers (3000 MT/day).
iii. Sending required amount of primary (300T/hr) and secondary air (600T/hr) to the boiler.
iv. Supplies superheated steam (5400C) of adequate temperature and pressure to turbines.
v. Extracting flue gases from the boiler and discharging them to atmosphere.
vi. Removing bottom ash formed as a result of combustion process.
vii. Removing fly ash from electrostatic precipitator hoppers.
11.3 TYPES OF BOILER USED IN POWER PLANTS: -
Conventional, Single Drum, Tangentially fired, balanced draught, Natural Circulation, Radiant Reheat Type, Dry Bottom with Direct Fired Pulverized Coal with Bowl Mill or with Fuel Oil.

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Fig. 11.1 Corner Fired Boiler Fig. 11.2 Balance Draft Boiler
210 MW BOILERS TECHNICAL SPECIFICATIONS: -
BOILER TYPE
TANGENTIALLY FIRED OR CORNER FIRED
COAL
BITUMINOUS COAL
FC
VM
MOIST
37.30%
27.60%
10%
ASH
GRINDABILITY
CV
25%
50 HGI
5000 KCAL/KG
FURNACE
WIDTH
DEPTH
VOLUME
13.8C8M
10.592M
5495 M³
TYPE FUSION WELDED TYPE
WARM UP OIL
LIGHT DIESEL OIL
TOTAL HEATING SURFACE AREA
22862.10 SQ.M
Table 11.1 Boiler Technical Specifications

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FEED WATER CYCLE: -
DM Water – Feed Storage Tank – Boiler Feed Pump – HP Heaters –LP Heaters – Feed Station – Economizer – Boiler Drum – Boiler Tubes
BOILER PARAMETERS: -
MAIN STEAM FLOW @ SH OUTLET
700 T/HR
MAIN STEAM TEMP @ SH OUTLET
540 ºC
MAIN STEAM PRES @ SH OUTLET
137 KG/CM²
REHEAT STEAM FLOW
578.3T/HR
REHEAT STEAM TEMP @REHEAT OUTLET
540 ºC
REHEAT STEAM PRESSURE@REHEAT OUTLET
25.1 KG/CM²
REHEAT STEAM PRESSURE@REHEAT INLET
27 KG/CM²
FEED WATER TEMP. ECONOMISER INLET
247 ºC
Table 11.2 Boiler Parameters
11.4 BOILER MAIN AUXILIARIES: - Auxiliaries of steam boiler are devices that be installed to the steam boiler, and can make it operates efficiently. These devices should be maintained and controlled, so steam boiler can run in good condition. Some of auxiliaries which are installed in steam boiler are:
11.4.1 COAL CYCLE: -
Coal is pulverized and feed into the boiler in the following steps-
• Coal mine - unshaped, unsized raw bituminous coal –crusher – bunker (stack).
• Coal bunkers (20mm size coal) – coal feeders (controlling input to coal mill) – coal mills.
• Powder, pulverized coal lifted by primary air and sending through coal pipes - coal dampers - to furnace for combustion.

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11.4.2 FUEL (FO / LDO) OIL CYCLE: -
• Furnace Oil (FO) / Light Diesel Oil (LDO) Tanks – Fuel Oil Pumps – Heaters (Steam) – Oil Dampers - Oil Guns – To Furnace
• Furnace Oil Is Non Explosive, Difficult To Ignite In Bulk, No Spontaneous Combustion
• Expensive Rs. 45-60 Thousand/Kl
BOILER AUXILIARIES
QUANTITY IN NUMBERS
AIR HEATERS
02 NOS.
FUEL OIL PUMPS
03 NOS.
OIL GUNS / IGNITORS
12 NOS. (4 NOS. AT 1 ELEVATION)
COAL MILLS
06 NOS.
PRIMARY AIR FANS
02 NOS.
FORCE DRAFT FANS
02 NOS.
INDUCED DRAFT FANS
02 NOS.
BOILER FEED PUMPS
03 NOS.
EMERGENCY LIFT PUMPS
02 NOS.
SEAL AIR FANS
02 NOS.
SCANNER FANS
02 NOS.
BOTTOM ASH GRINDERS
04 NOS.( 2NOS. FOR ONE PASS)
ELECTROSTATIC PRECIPETATOR
24 ESP FIELDS (48 HOPPERS)
Table 11.3 Required Boiler Auxiliaries
11.4.3 AIR CYCLE: -
• Primary Air Fans: – Mixture cold & hot air supplies to lifting coal to furnace.
• Forced Draft Fans: – Supplies hot air required for combustion. The function of forced draft fans is to supply the combustion air initially, when no coal firing is taking place. But once the coal firing starts, the function of forced draft fan remains only to supply air required for completing combustion process.

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• Balanced Draft: - Balanced draft is obtained through use of both induced and forced draft. This is more common with larger boilers where the flue gases have to travel a long distance through many boiler passes. The induced draft fan works in conjunction with the forced draft fan allowing the furnace pressure to be maintained slightly below atmospheric.
• Induced Draft Fans: – Maintain continuity of combustion and maintain negative pressure (-ve). Extract flue gases from furnace and discharge them to atmosphere.
• Primary Air: - This air lifts the pulverized coal from the coal mills & enters the boiler with it. The primary air quantity is less with pressure higher so that it can lift the coal. This air is also used to dry the coal.
• Secondary Air: - As air supplied wet coal (Primary air) is less in quantity it is not sufficient for complete combustion & some quantity of air must be supplied additionally to complete combustion. This is called secondary air.
• Seal Air Fans: - These fans take the suction from cold air duck of primary air system & their discharge goes to the sealing of gear box of coal mills & its rollers for bearing sealing.
• Scanner Fans: - Scanner fans air supply the cooling air necessary for the cooling of costly scanner heads. Scanner heads may get damaged if not cooled, leading to outage of units. These fans take their suction from the discharge of FD in the discharge of these fans goes to scanner after getting filtered. In case of AC failure when FD fans trip, there is provision to provide suction to these fans from atmosphere.
• Soot Blower System: - The fuel used in thermal power plants causes soot and this is deposited on the boiler tubes, economizer tubes, air pre heaters, etc. This drastically reduces the amount of heat transfer of the heat exchangers. Soot blowers control the formation of soot and reduce its corrosive effects. The types of soot blowers are fixed type, which may be further classified into lane type and mass type depending upon the type of spray and nozzle used. The other type of soot blower is the retractable soot blower. The advantages are that they are placed far away from the high temperature zone, they concentrate the cleaning through a single large nozzle rather than many small nozzles and there is no concern of nozzle arrangement with respect to the boiler tubes.

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11.5 IMPROVING BOILER AND OVERALL EFFICIENCY OF PLANT: -
• Economizer: - Absorbs heat from flue gas and add this sensible heat to feed water before water enters to Boiler. The justifiable cost of the economizer depends on the total gain in efficiency. In turn this depends on the flue gas temperature leaving the boiler and the feed water inlet temperature.
• Air Pre-Heater: -Flue gases passes through Heater tubes and Cold air passes through air heater heated up and Hot air used for combustion. An air preheater or air heater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a recuperative heat system or to replace a steam coil.
• Super Heaters: - The super heater is a heat exchanger in which heat is transferred to the saturated steam to increase its temperature. It raises the overall cycle efficiency. In addition, it reduces the moisture content in the last stages of the turbine and thus increases the turbine efficiency. The superheater consists of a superheater header and superheater elements. Steam from the main steam pipe arrives at the saturated steam chamber of the superheater header and is fed into the superheater elements. Superheated steam arrives back at the superheated steam chamber of the superheater header and is fed into the steam pipe to the cylinders. Superheated steam is more expansive.
• Reheater: - The reheater functions similar to the superheater in that it serves to elevate the steam temperature. Primary steam is supplied to the high pressure turbine. After passing through the high pressure turbine, the steam is returned to the steam generator for reheating (in a reheater) after which it is sent to the low pressure turbine. A second reheat cycle may also be provided.
11.6 FLUE GAS PATH: -
• Whenever combustion takes place chemical energy converted into heat energy (depends on CV).
• Various gases CO2, SO2, N2, water vapor produced.
• Heat carried away through flue gas is used in Air Heater & Economizer to improve Boiler Efficiency.

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• Temperature of the flue gases at various stages is given below in the index for (210
MW) Rated output plant. Parameters of flue gas may vary from one plant to other.
Table 11.4 Flue Gas Parameters at Various Stages
Eco
Drum
S/H R/H S/H
LTSH
Boiler
WindBox
APH
ESP
ID fan
Coal
Bunker
Coal Mill
Feeder
FD Fan
PA Fan
Coal from
CHP
Chimney
COAL AND FLUE GAS CYCLE
HFO
Fig. 11.3 Coal and Flue Gas Cycle
FLUE GAS PATH OUTLET TEMPERATURE
IN 0 C
FURNACE 1123
PLATTERN SUPER HEATER 1010
REHEATER FRONT 823
REHEATER REAR 765
FINAL SUPER HEATER 662
HORIZONTAL SUPER HEATER 479
ECONOMISER 369
AIR HEATER 140
E.S.P. 125
I.D.FAN 120
CHIMNEY 120

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Materials used for the boiler tubes as per ASME: -
Material
ASTM
Specification
Grade
Temperature
Carbon Steel
SA 210
A1
450oC
Carbon ¼ % MO Steel
SA 209
T1
480Oc
1 % Cr, ½ % MO Steel
SA 213
T11
550oC
2 ½ % Cr, 1 % MO Steel
SA 213
T22
580oC
18% Cr, 8 % Ni Stainless Steel
SA 213
T304
Up to 700oC
Table 11.5 Materials for Boiler Tubes
11.7 BOILER AUXILIARIES SPECIFICATIONS: -
 Induced Draft Fan: -
MOTOR
UNIT NO.3
UNIT NO.4
UNIT NO.5
FAN
MAKE
BHEL
BHEL
BHEL
MAKE
BHEL
CAPACITY
1700
1300
1300
CAPACITY
232.5M³/SEC
SPEED
990
990
990
TYPE
AXIAL IMPULSE
VOLTAGE
6.6
6.6
6.6
SPEED
990 RPM
CURRENT
175
138
138
NO. OF FAN / BOILER
2
Table 11.6 ID Fan Technical Specifications
 Primary Air Fan: -
MAKE
BHEL
MAKE
BHEL , KKK
CAPACITY
1250 KW
TYPE
SINGLE SUCTION RADIAL
VOLTAGE
6.6 KV
FAN SIZE
NDF-21 b U#3
FAN SIZE
NDFV-22b U#4&5
SPEED
1480 RPM
CAPACITY
70.33 M³/SEC
Table 11.7 PA Fan Technical Specifications

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 Forced Draft Fan: -
Table 11.8 FD Fan Technical Specifications
 Air Pre-Heater: -
TYPE
TRISECTOR ROTARY AIR PREHEATER(LIUNGSTORM)
MAIN DRIVE MOTOR
SIZE
27 VI 72
MAKE
CROMPTON GREAVES
NO OF AIR HEATERS
2
CAPACITY
11 KW
INSTALLED POSITION
VERTICAL
VOLTAGE
415 V
HEIGHT OF HOT END LAYER
1067 MM
CURRENT
22 AMP
HEIGHT OF INTERMEDIATE LAYER
457 MM
SPEED
1440 RPM
HEIGHT OF COLD END LAYER
305 MM
DRIVE MOTOR
2 NOS.
GAS TEMP.
141 ºC
Table 11.9 Air Pre-Heater Technical Specifications
MOTOR
UNIT NO.3
UNIT NO.4
UNIT NO.5
FAN
MAKE
BHEL
BHEL
BHEL
MAKE
BHEL
CAPACITY
630
750
750
CAPACITY
105.5 M³/SEC
SPEED
990
1491
1491
TYPE OF FAN
AXIAL IMPULSE
VOLTAGE
6.6
6.6
6.6
FAN TYPE
AN 20e6 U#3
CURRENT
68
79
79
TYPE OF FAN
AXIAL REACTION
IGV OPERATIO
PNEUMATIC
HYDRAULIC
HYDRAULIC
FAN TYPE
API-18/11 U#4&5

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CHAPTER 12
TURBINE OPERATION, MAINTAINANCE AND ITS AUXILIARIES
12.1 INRODUCTION: -
Turbine is an engine that converts energy of fluid into mechanical energy. The steam turbine is steam driven rotary engine.Steam Turbine Converts the Heat Energy (Kinetic Energy) into Mechanical Energy.
12.2 WORKING PRINCIPLE OF STEAM TURBINE: -
i. A steam turbine works on the principle of conversion of High pressure & temperature steam into high Kinetic energy, thereby giving torque to a moving rotor.
ii. For above energy conversion there is requirement of converging /Converging- Diverging Sections.
iii. Such above requirement is built up in the space between two consecutive blades of fixed and moving blades rows.
12.3 TYPES OF STEAM TURBINE: -
According to the principle of action of the steam, turbine can be classified as:
i. Impulse Turbine: - In a stage of Impulse turbine the pressure/Enthalpy drop takes place only in fixed blades and not in the moving blades.
ii. Reaction Turbine: - In a stage of Reaction Turbine the Pressure/enthalpy drop takes place in both the fixed and moving blades.
TURBINES IN NTPS NASHIK: -
210 MW Turbine at Nashik is three cylinders (HP, IP, LP) Tandem compound with nozzle governing, condensing & regenerative feed heating type.
• The HPT comprises of 12 stages, the first stage being governing stage.
• The IPT comprises of 11 stages.
• The LPT has 4+4 stages .Steam enters at middle & flows in opposite paths having four stages.
Turbine rotors are supported on five bearings .The common bearing of HP & IP rotor is a combined journal & radial thrust bearing. Rest four bearings are journal bearings.
12.4 CONSTRUCTION AND STEAM FLOW: -

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 The turbine is tandem compound machine with HP, IP, & LP parts. The HP part is a single flow cylinder & IP & LP parts are double flow cylinders.
 The individual rotors & generator rotor are connected by rigid couplings.
 The HP cylinder has a throttle control. The initial steam is admitted before the blading by two combined main steam stop & control valves.
 The lines leading from the two HP exhaust branches to the re heater are provided with swing a check valve which prevents hot steam from re heater flowing back in to the HP cylinder.
 The steam coming from the re heater is passed to the IP part via two combined reheat stop & control valves cross around pipes connect the IP & LP cylinders.
 Bleeds are arranged at several points of the turbine.
12.5 VALVES: -
It is a mechanical device to control the flow of fluid in pipe. Valves are said to be nerve centre of power plant controlling high pressure steam & water.
 The HP turbine is fitted with two initial steam stop & control valves.
 A stop & control valve with stems arranged right angle to each other are combined in a common body.
 The stop valves are spring operated single-seat valves, the control valves, are also of single seat design, have diffusers to reduce pressure losses.
 The IP turbine has two combined reheat stop &control valves.
 The reheat stop valves are spring loaded single seat valves.
 The control valves, also spring loaded, have diffusers. The control valves operate in parallel & are fully open in the upper load range.
 In the lower load range, they control the steam flow to the IP turbine & ensure stable operation even when turbo set is supplying only the station load.
 Both the main & reheat stop & control valves are supported kinematically on foundation ceiling below the machine floor before the turbo set.
 All valves are individually operated by oil hydraulic servomotors.
12.6 TURBINE GOVERNING SYSTEM: -

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 The turbine has an electro-hydraulic governing system backed with a hydraulic governing system.
 An electric system measures & controls speed & output, & operate the control valves hydraulically in conjunction with an electro hydraulic converter.
 The electro hydraulic governing system permits run up control of turbine up to rated speed & keeps speed swings following sudden load shedding low.
 The linear output frequency characteristic can be very closely set even during operation.
12.7 OIL SUPPLY SYSTEM: -
 A single oil supply system lubricates & cools the bearing, governs the machine operates the hydraulic actuators & safety and protective devices & drives the hydraulic turning gear.
 The main pump is driven by the turbine shaft draws oil from the main oil tank. Auxiliary oil pumps maintain the oil supply on start up & shut down. During turbine gear operation & when MOP is faulted.
 When the turning gear is stared, jacking oil pumps force high pressure oil under the shaft journals to prevent boundary lubrication.
 The lubricating & cooling oil is passed through oil coolers before oil supply.
12.8 TURBINE MONITORING SYSTEM: -
 In addition to measuring instruments & instruments indicating pressures, temperatures, valve positions &speed, the monitoring system also includes measuring instruments & indicators for the following values.
 Absolute expansion, measured at the front & rear bearing pedestal of the HP turbine.
 Differential expansion between the shafting & turbine casing, measured at several points.
 Bearing pedestal vibrations, measured at all turbine bearings.
 Relative shaft vibrations measured at all turbine bearings .absolute shaft vibrations, obtained from bearing pedestal vibration & relative shaft vibration by calculation.
12.9 FIXED POINTS: -
 There is no restriction on axial movement of the casings.

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 In designing the supports of the turbine on the foundation, attention is given to the expansion and contraction of the machine during thermal cycling.
 Excessive stresses would be caused in the components if the thermal expansion or contractions were restricted any way.
 The method of attachment of the machine components, and their coupling together, are also decisive factors in determining the magnitude of the relative axial expansion between the rotor system & turbine casings, which is given careful attention when determining the internal clearances in the design.
TURBINE MAIN DATA: -
RATED OUTPUT OF TURBINE
210 MW
RATED SPEED
3000 RPM
RATED PRESSUE OF STEAM BEFORE EMERGENCY STOP VALVE
130 KG/CM²
RATED LIVE STEAM TEMPERATURE
535 ºC
RATED STEAM PRESSURE
23.20 KG /CM²
RATED STEAM PRESS. AF
535 ºC
STEAM FLOW
616 TON/HR
STEAM FLOW AT VALVE WIDE OPEN CONDITION
670 TON/HR
RATED PRESSURE AT THE EXHAUST OF LPT
63.3 MM HG COL
RATED CIRCULATING WATER TEMP.
30 ºC
RATED QUALITY OF CIRC
27000 M³/HR
Table 12.1 Turbine Technical Specifications
OIL PUMPS: -
MOTOR
PUMP
MAKE
BHEL,HARIDWAR
MAKE
MATHER & PLATT,PUNE
CAPACITY
200 KW
SPEED
970 RPM
VOLTAGE
6.6 KV
HEAD
220 M
CURRENT
21.8 AMP
DISCHARGE
200 M³/HR
SPEED
985 RPM
Table 12.2 Oil Pump Technical Specifications

35
Fig. 12.1 Steam Turbine and Regenerative Heating
Fig. 12.2 Steam Turbine Rotor

36
12.10 STEAM TURBINE STARTS UP: -
When warming up a steam turbine for use, the main steam stop valves (after the boiler) have a bypass line to allow superheated steam to slowly bypass the valve and proceed to heat up the lines in the system along with the steam turbine. Also a turning gear is engaged when there is no steam to the turbine to slowly rotate the turbine to ensure even heating to prevent uneven expansion. After first rotating the turbine by the turning gear, allowing time for the rotor to assume a straight plane (no bowing), then the turning gear is disengaged and steam is admitted to the turbine, first to the astern blades then to the ahead blades slowly rotating the turbine at 10 to 15 RPM to slowly warm the turbine.
12.11 PRECAUTIONS DURING RUNNING: -
Problems with turbines are now rare and maintenance requirements are relatively small. Any imbalance of the rotor can lead to vibration, which in extreme cases can lead to a blade letting go and punching straight through the casing. It is, however, essential that the turbine be turned with dry steam. If water gets into the steam and is blasted onto the blades (moisture carryover) rapid impingement and erosion of the blades can occur, possibly leading to imbalance and catastrophic failure. Also water entering the blades will likely result in the destruction of the thrust bearing for the turbine shaft. To prevent this, along with controls and baffles in the boilers to ensure high quality steam, condensate drains are installed in the steam piping leading to the turbine.
12.12 MATERIALS FOR STEAM TURBINE DESIGN: -
i. Blades
 Stainless Steel – 403 & 422 (+Cr)
 17-4 PH steel (+ Ti)
 Super Alloys
ii. Rotor
 High “Chrome – Moley” Steel – Cr-Mo-V
 Low “Ni Chrome Steel – Ni-Cr-Mo-V

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CHAPTER 13
GENERATOR
13.1 INTRODUCTION: - In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit. The source of mechanical energy may vary widely from a hand crank to an internal combustion engine and turbine used in power plants. Generators provide nearly all of the power for electric power grids.
13.2 PRINCIPLE OF GENERATION: - GENERATION OF AC POWER
The basic requirements for generation of AC power are as follows.
i. Conductor
ii. Magnetic field
iii. Relative speed
Faraday's laws of electromagnetic induction
 First Law: - Whenever there is change in magnetic flux associated with a coil, an emf is induced in it.
 Second law: - The magnitude of induced emf is directly proportional to the rate of change of flux through the coil.
Maximum electric speed to be achieved is 3000 RPM being 50 cycles per sec. is the quality of electric supply in our India.
Thus maximum speed shall be achieved by 2 poles machine. However multi pole generators are used for Hydro Power Stations as speed depends upon depth of reservoirs i.e., water pressure, water head available at first stage of runner of turbine.

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Fig. 13.1 Turbo-Generator
Fig. 13.2 Generator Transformer

39
CHAPTER 14
STEAM CONDENSING SYSTEM
14.1 INTRODUCTION: - Thermoelectric power plants boil water to create steam, which then spins turbines to generate electricity. The heat used to boil water can come from burning of a fuel, from nuclear reactions, or directly from the sun or geothermal heat sources underground. Once steam has passed through a turbine, it must be cooled back into water before it can be reused to produce more electricity. Colder water cools the steam more effectively and allows more efficient electricity generation. Wet-recirculating or closed-loop systems reuse cooling water in a second cycle rather than immediately discharging it back to the original water source. Most commonly, wet- recirculating systems use cooling towers to expose water to ambient air. Some of the water evaporates; the rest is then sent back to the condenser in the power plant. Because wet- recirculating systems only withdraw water to replace any water that is lost through evaporation in the cooling tower, these systems have much lower water withdrawals than once-through systems, but tend to have appreciably higher water consumption.
14.2 STEAM CONDENSING SYSTEM COMPONENTS: -
i. Condenser
ii. Cooling tower
iii. Hot well
iv. Condenser cooling water pump
v. Condensate air extraction pump
vi. Air extraction pump
vii. Boiler feed pump
viii. Make up water pump
ix. Deaerator
x. Air Ejector
xi. Drain Cooler
xii. Feed Water Heaters (HP/LP Heaters)

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Condenser: -
The main purposes of the condenser are to condense the exhaust steam from the turbine for reuse in the cycle and to maximize turbine efficiency by maintaining proper vacuum. As the operating pressure of the condenser is lowered (vacuum is increased), the enthalpy drop of the expanding steam in the turbine will also increase. This will increase the amount of available work from the turbine (electrical output). By lowering the condenser operating pressure, the following will occur:
a. Increased turbine output
b. Increased Plant efficiency
c. Reduced steam flow
Fig. 14.1 Diagram of a Typical Water-cooled Surface Condenser
Hot Well: -
These are small storage tank of condensate water below condensers. They are maintained at required level of condensate with the help of Hot Well Level Controller, provided just before drain cooler. They are also equipped with make-up lines from DM Storage Tank and Surge Tank.
Suction Well: -
This is the storage well of condensate water and condensate pump is submerged in this well. It is provided with continuous vent connection to condenser to maintain the flow of condensate water from condenser by neglecting its vacuum.

41
Condensate Pump: -
There are two multistage centrifugal condensate pumps but both are capable of delivering full load individually. It delivers condensate to SPE.
Cooling Tower: -
A cooling tower extracts heat from water by evaporation. In an evaporative cooling tower, a small portion of the water being cooled is allowed to evaporate into a moving air stream to provide significant cooling to the rest of that water stream.
Cooling Towers are commonly used to provide lower than ambient water temperatures and are more cost effective and energy efficient than most other alternatives. The smallest cooling towers are structured for only a few litres of water per minute while the largest cooling towers may handle upwards of thousands of litres per minute. The pipes are obviously much larger to accommodate this much water in the larger towers and can range up to 12 inches in diameter.
When water is reused in the process, it is pumped to the top of the cooling tower and will then flow down through plastic or wood shells, much like a honeycomb found in a bee’s nest. The water will emit heat as it is downward flowing which mixes with the above air flow, which in turn cools the water. Part of this water will also evaporate, causing it to lose even more heat.
Steam Packing Exhauster (SPE): -
This is a surface type heat exchanger which transfers the heat energy of packing steam to the condensate water and condenses packing steam (drip) in turn, which are drained to the condenser through an atmospheric drain tank. Its shell is equipped with an Air Blower to evacuate non-condensable gases to atmosphere.
Air Ejector: -
It is a double stage twin steam jet ejector which acts as an air pump. Its main function is to maintain vacuum by pulling out air and non-condensable gases from the condenser. Exhaust steam from jet ejector are made to pass from inter and after condenser where heat of jet steam is transferred to condensate coming from SPE.

42
Drain Cooler: -
The air from condensate water, which is exhausted to atmosphere through a vent condenser. The bled steam directly condenses and gets mixed with condensate water from heater, and this is passed to storage tank.
Deaerator: - A deaerator is a device that is used for removal of oxygen and other dissolved gases from the feed water to steam-generating boilers. In particular, dissolved oxygen in boiler feed water will cause serious corrosion damage in steam boiler systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). Dissolved carbon dioxide combines with water to form acid that causes further corrosion.
Feed Water Heaters: -
This item is installed to improve power generator efficiency by heating supplied water and reducing breakage due to heat stress from temperature differences in boiler tubes. Because a single heater consists of cooling areas, condensing areas, and heating areas, this item requires thoughtful engineering and production.
Feed water heaters are classified as low and high pressure heaters with one heater consisting of overheating, condensing and overcooling areas, making it difficult to design and produce.
Use one or more low pressure feed water heaters to raise the temperature of condensate from condensate pump discharge temperature to the de-aerator inlet temperature. Use one or more high pressure feed water heaters to raise the temperature of feed water from de-aerator outlet temperature to the required boiler economizer inlet temperature.
Condenser Data: -
MAKE
BHEL
COOLING SURFACE AREA
14650 M²
NO. OF COOLING TUBES
15652
LENGTH OF COOLING TU
10M
DIA.OF COOLING TUBE
30/28 MM
NO. OF WATER PATHS FOR EACH CONDENSER
2
DESIGNED CONSUMPTION OF COOLING WATER
27000 M³/HR
QUANTITY OF STEAM CONDENSING
150 TO 500 T/HR
MAIN EJECTOR
2 NOS.
STARTING EJECTOR
1 NO
Table 14.1 Condenser Technical Specifications

43
CHAPTER 15
BOILER FEED WATER PUMP
15.1 INTRODUCTION: - A boiler feed water pump is a specific type of pump used to pump feed water into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are normally high pressure units that take suction from a condensate return system and can be of the centrifugal pump type or positive displacement type.
15.2 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 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. Another common form of feed water pumps run constantly and are provided with a minimum flow device to stop over pressuring the pump on low flows. The minimum flow usually returns to the tank or deaerator.
Boiler Feed Pump Data: -
MOTOR
PUMP
MAKE
BHEL , HARDWAR
MAKE
BHEL,HYDERABAD
CAPACITY
4000 KW
TYPE
200 KHI
VOLTAGE
6.6 KV
NO.OF STGES
6
CURRENT
408 AMP
SPEED
4320 RPM
SPEED
1485 RPM
LUBRICATION
FORCED
Table 15.1 BFP Technical Specifications
HEAD
1830 MLC
DISCHARGE
430 T/HR

44
CHAPTER 16
ASH HANDLING PLANT
16.1 INTRODUCTION: -
To generate one unit, as per design we have to burn 0.55 kg coal. But actually we have to burn 0.65 kg coal.
Indian coal has
 Calorific Value- 5000 Kcal/ Kg.
 Fixed Carbon – 38%
 Volatile Matter – 26%
 Moisture – 8%
 Ash Content – 28%.
16.2 TYPES OF COAL ASH: -
Coal ash is the residue of the coal combustion process involved in the thermal power plants. The types of coal ash from coal based thermal power plants are:
i. Fly Ash: - Collected from different rows of electrostatic precipitator.
ii. Bottom Ash: - Collected at the bottom of boiler furnace.
iii. Pond Ash: - Mixture of bottom ash and fly ash as available in ash disposal ponds.
One 210 mw set requires
0.65*5.04*1000=3276 tonne coal per day.
Ash content is 28%
I.e. 3276*0.28=917.28 tonne i.e. 920 tonne.
Out of this 28% ash
 Bottom ash 15 to 20% i.e. 138 to 184 tonne
 Fly ash 80 to 85% i.e. 734 to 780 tonne
Contents of ash-
 Silica
 Alumina
 Iron oxide

45
 Calcium
 Magnesium
 Sulphate
 Alkalis
16.3 BOTTOM ASH SYSTEM: -
It consists following main components:
 Bottom ash hopper
 Clinker grinder
 Ejector feed pump
 Hydro ejector
16.4 FLY ASH SYSTEM: -
The system for all units is identical and following description is applied to both the units the water compounded bottom ash hopper receives the bottom ash from the furnace from where it is stores and discharged through the clinker grinder. Two slurry pumps are provided which is common to all units & used to make slurry and further transportation to ash dyke through pipeline.
Ash particles are separated by passing through electrical field (Electrostatic Precipitator).
Components in ESP: -
• Discharge electrode (-ve)
• Collecting electrode (+ve )
• Rapping mechanism
• Fly ash hopper
• High tension voltage equipment
16.5 AREAS OF FLY ASH UTILISATION: -
Fly ash can be used for various applications. Some of the major areas of fly ash utilization are as follow:
 Fly ash bricks
 Fly ash cement
 Reclamation of waste land

46
 Fly ash based components for construction industry.
 Sintered aggregate
 Wood substitute – doors & panels
 Granite substitute
 Ceramic tiles
 Paints & enamels
 Reclamation of ash ponds for human settlement
Fig. 16.1 Electrostatic Precipitator
Common causes of unsatisfactory performance of ESP are:
 Excessive gas volume
 Overloading
 Ineffective rapping

47
 Overfilling of dust hoppers
 Poor gas distribution
 Flashover and electrical instability
 Discharge wire breakage
Fig 16.2 Typical View of Ash Handling Plant

48
CHAPTER 17
ENERGY CONSERVATION AND ENERGY AUDIT
17.1 ENERGY CONSERVATION: -
Energy conservation means to reduce the quantity of energy that is used for different purposes. This practice may result in increase of financial capital, environmental value, national and personal security, and human comfort.
Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote economic, political and environmental sustainability.
On a larger scale, energy conservation is an important element of energy policy. In general, energy conservation reduces the energy consumption and energy demand per capita. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production. By reducing emissions, energy conservation is an important method to prevent climate change. Energy conservation makes it easier to replace non-renewable resources with renewable energy. Energy conservation is often the most economical solution to energy shortages.
17.2 ENERGY AUDIT: - An Energy Audit is a systematic exercise to identify end-uses that consume a significant amount of energy, estimate the efficiency in each of these end uses and devise methods of improving efficiency curbing losses and wasteful use or in other words it is an inspection, survey and analysis of energy flows for energy conservation in a building, process or system to reduce the amount of energy input into the system without negatively affecting the output.
It attempts to balance the total energy inputs with its use and serves to identify all the energy streams in a facility. When the object of study is an occupied building then reducing energy consumption while maintaining or improving human comfort, health and safety are of primary concern. Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost effective opportunities for energy savings.

49
CHAPTER 18 CONCLUSION It was a knowledgeable experience while taking practical training at NASHIK THERMAL POWER STATION. It proved an opportunity for encounter with such huge machines like tippler, turbine, boiler and generator. But there are few factors that require special mention. From all the study it can be concluded that the Nasik thermal power project of 210X3 units is fairly organized unit with the latest machinery available. The turbine is a very sophisticated assembly of machinery which requires specific conditions of steam temperature and pressure to work efficiently. Any alteration of the specific requirements may prove hazardous to the turbine. Another interesting yet worrying fact is the quantity of coal consumed which approximately 3276 tonne per day. The level of pollution is always controlled according the established norms, but still I consider it to be quite enough. Well, efforts are always underway in reducing the pollution and improving the efficiency of the plant. All in all, a thermal power project is very large establishment with many components and it awesome to see how all the components work in a synchronized manner.
The Electricity Act 2003 and subsequent National Electricity Policy and Tariff Policy have
Opened up several opportunities for the power sector. The Act allows the IPPs and captive
Power producers open access to transmission system, thus allowing them to bypass the SEBs
and sell power directly to bulk consumers. Slowly open access in distribution system is also being allowed.
Assessment of the financial feasibility of the Proposed Project, delivers satisfactory financial
Parameters as per base financial model. It has also assessed the viability of the project under the impact of various scenarios, which could be at variance with the base case scenario assumed. Company has proposed to set-up 660 MW Coal fired Thermal Power Project based on
Super Critical Technology. State Government has supported this Project and has issued letter of support to provide all kind of administrative support required.

50
CHAPTER 19
SUGGESTIONS Power sector is an essential service and in the basis of industrialization and agriculture. It plays a vital role in the socio-economic development. Therefore, improving efficiency of these thermal power stations in addition to increasing their PLF (Plant Load Factor) has become the need of the hour to bring the cost and maximize the generation levels. With this objective in view, several actions have already been initiated by Ministry of Power (MOP) and other various agencies like CEA, NTPC, State Electricity Boards, CBIP etc. to improve the operating efficiency and PLF of thermal power stations. Now I here make it sort with my suggestions for improving efficiency of power plant and for various other factors on the basis of what I have learned during my training are:
 With the deficit of electricity in our country, there is need of many projects and the exposure limit should be increased to effectively assist the new projects.
 Proper maintenance of ESP must be done with regular maintenance of boilers and furnaces.
 Variable speed motors should be used.
 Auxiliaries power reduction.
 Use of automatic system for monitoring flue gases.
 Completely insulate the steam system.
 Turbine driven Boiler Feed Pumps should be used.
 The plant is working fine with not many hindrances, but the main concern is the cleanliness of plant. The plant, especially 140X2 units building of the plant is not clean enough. What I believe is that cleaner environment might help in improving of productivity and decrease the rate of breakdowns. This might improve the efficiency of the unit as lesser number of foreign elements will be present which prevent the proper functioning of the unit. If the efficiency increases, the coal consumption will be reduced for the same load and that would provide better profit to the organization.
 Recover the portion of heat loss from the warm cooling water existing the steam condenser.  Reduce air, water, steam and flue gas leakages.

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