Pavan Paga: 2011

THERMAL POWER IN INDIA-PROBLEMS, PROSPECTS AND LATEST DEVELOPMENTS

A SEMINAR REPORT

Submitted by

PAVAN

(8^th semester, USN-2BV07IPxxx)

Towards partial fulfillment for the award of the degree of

BACHELOR OF ENGINEERING

DEPARTMENT OF INDUSTRIAL AND PRODUCTION ENGINEERING

B V B COLLEGE OF ENGINEERING & TECHNOLOGY

HUBLI – 580031 (India)

March-2011

K L E Society’s

B.V.B. COLLEGE OF ENGG AND TECHNOLOGY

HUBLI-31

Department of Industrial & Production Engineering

CERTIFICATE

This is to certify that the SEMINAR REPORT entitled “THERMAL POWER IN INDIA, PROBLEMS, PROSPECTS AND LATEST DEVELOPMENTS” submitted by Pavan, to the B.V. Bhoomaraddi College of Engineering and Technology, Hubli 580031 (India) towards partial fulfillment for the award of the degree of Bachelor of Engineering is a bona-fide record of work carried out by him under our supervision. The contents of this seminar report, in full or in parts, have not been submitted to any other institute or university for award of any degree or diploma.

Head of the Department

Guide

Dr. B. B. Kotturshettar Prof.Prasanna Raravi

ACKNOWLEDGEMENT

At the outset, I express my deep sense of gratitude to my guide, Prof. Prasanna Raravi for his valuable and inspiring guidance throughout the course of this work. I would like to thank him for providing me an excellent ambience and freedom of thought. I have always been admiring his patience, perseverance and guidance. He has driven me to an everlasting debt of gratitude through his valuable guidance and support in bringing out this seminar report.

I wish to express my sincere thanks to Prof. B.B.KOTTURSHETTER, Head of The Department of INDUSTRIAL PRODUCTION, B.V.BHOOMARADDI COLLEGE OF ENGINEERING AND TECHNOLOGY, Hubli-580031 for providing his guidance.

ABSTRACT

Due to the growth in population and industrial growth the demand for power is increasing in the country by leaps and bounds. But the power production through hydro-electric projects and through nuclear power projects is not keeping pace with the demand. Thermal power offers a ray of hope in this scenario. Power development is the key to the economic development. The per capita consumption of electricity in the country also increased from 15 kWh in 1950 to about 338 kWh in 1997 -98, which is about 23 times. However this is very small compared to the developed world. Still about 15% of the villages are not electrified. The quality and quantity of electricity supply is also very poor.

India’s 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 needs to be encouraged in all possible manner not only to increase the thermal power production but also to increase its efficiency by adopting latest technological innovations.

Ultra Mega Power projects (UMPP) are a series of ambitious power projects planned by the Government of India. With India being a country of chronic power deficits, the Government of India has planned to provide 'power for all' by the end of the eleventh plan (by 2012). This would entail the creation of an additional capacity of at least 100,000 MW by 2012. The Ultra Mega Power projects, each with a capacity of 4000 megawatts or above, are being developed with the aim of bridging this gap. Already some UMPP’s are under implementation at Saasan-(Reliance Energy), Mundra-(TATA power), Kudagi-(NTPC) etc.

Hitachi has recently developed products and services for advanced support for maintenance and preservation through the use of IT (information technology) and network technology, going beyond what has previously been available. This technological innovation needs to be adopted by the existing as well as forth coming power plants not only to increase the efficiency of power production but also to increase the life of the power plants.

The per capita availability and consumption of electricity is very less in the country as compared to the developed world. The rapid economic growth and the resultant increased standard of living of the population calls for huge increase in supply of power. The growing population as well as rapidly expanding industry also demands for a huge supply of power. In this context increasing thermal power production assumes great significance in the country.

Chapter No. TITLE Page No.

Acknowledgement 3

Abstract 5

1. Introduction

1.1 History 8

1.2 Efficiency 8

1.3 Growth of Indian power sector 9

1.4 Development of coal based generation 10

2. Working of Thermal Power plant 11

2.1 Typical coal fired thermal power station 11

2.2 Working of Thermal power plant 12

2.3 Advantages 13

2.4 Disadvantages 13

3. Environmental impact of thermal power stations 14

3.1 Air pollution 14

3.2 Nitrogen Oxide 14

3.3 Sulphur Oxide 15

3.4 Technology up gradation 16

4. Role of NTPC and Power Generation 17

4.1 Overview 18

4.2 Ash Utilisation 19

4.3 CenPEEP 20

4.4 NTPC's Approach 22

5. Ultra Mega Power Projects 23

5.1 The Sasan Ultra Mega Power Project Reliance 23

5.2 Ultra Mega Power Project Tata Power 24

5.3 Ultra Mega Power Project NTPC 24

6. Advanced Technologies of Preventive Maintenance for 25

Thermal Power Plants

6.1 Overview 25

6.2 Introduction 26

6.3 Application of IT to Preventive 27

6.4 Preventive Maintenance Technology for Boilers 27

6.5 Scheduled inspection rationalization technology 28

6.6 Preventive Maintenance Technology for Steam 29

Turbines

6.7 Development of scheduled inspection technology 30

for improving in efficiency

6.8 Preventive Maintenance Technology for Gas 32

Turbines

6.9 Lifetime management and repair of hot gas path 32

Components

6.10 Gas turbine bucket recoating repair 33

6.11 Gas turbine nozzle blade diffusion brazing repair 33

7. CONCLUSION 34

8. REFERENCES 36

LIST OF TABLE AND FIGURES

Description Page no

Power generation in INDIA 8

Diagram of a typical coal fired thermal power station 11

Block Diagram 11

Area wise break-up of utilization for the year 2009-10 16

Growth of NTPC 18

Ultra Mega Power Projects 23

Preventive maintenance solutions 26

Diagnostic Technology 27

ELFOS UT performance 29

Mechanism for detection of steam leaks 30

Screen Images 32

Chapter-1

INTRODUCTION

The power sector has registered significant progress since the process of planned development of the economy began in 1950. Hydro -power and coal based thermal power have been the main sources of generating electricity. 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 development that has taken place, the power supply industry has been under constant pressure to bridge the gap between supply and demand.

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 center because such facilities convert forms of heat energy into electrical energy. 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 proportion of CO₂ is produced by the worlds fossil fired thermal power plants; efforts to reduce these outputs are various and widespread.

Almost all coal, nuclear, geothermal, solar thermal electric, and waste incineration plants, as well as many natural gas power plants are thermal. Natural gas is frequently combusted in gas turbines as well as boilers. The waste heat from a gas turbine can be used to raise steam, in a combined cycle plant that improves overall efficiency. Power plants burning coal, oil, or natural gas are often referred to collectively as fossil-fuel power plants. Some biomass-fueled thermal power plants have appeared also. Non-nuclear thermal power plants, particularly fossil-fueled plants, which do not use co-generation are sometimes referred to as conventional power plants.

1.1-History

Reciprocating steam engines have been used for mechanical power sources since the 18th Century, with notable improvements being made by James Watt. The very first commercial central electrical generating stations in the Pearl Street Station, New York and the Holborn Viaduct power station, London, in 1882, also used reciprocating steam engines. The development of the steam turbine allowed larger and more efficient central generating stations to be built. By 1892 it was considered as an 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. Turbines entirely replaced reciprocating engines in large central stations after about 1905. The largest reciprocating engine-generator sets ever built were completed in 1901 for the Manhattan Elevated Railway. Each of seventeen units weighed about 500 tons and was rated 6000 kilowatts; a contemporary turbine-set of similar rating would have weighed about 20% as much.

1.2 Efficiency

The energy efficiency of a conventional thermal power station, considered as salable energy (in MW) produced at the plant, is typically 33% to 48% efficient. This efficiency is limited as all heat engines are governed by the laws of thermodynamics . The rest of the energy must leave the plant in the form of heat. This waste heat can go through a condenser and be disposed of with cooling water or in cooling towers. If the waste heat is instead utilized for district heating, it is called co-generation. An important class of thermal power station are associated with desalination facilities; these are typically found in desert countries with large supplies of natural gas and in these plants, freshwater production and electricity are equally important co-products.

1.3 Growth of Indian Power Sector

Figure 1.1

Power development is the key to the economic development. The power Sector has been receiving adequate priority ever since the process of planned development began in 1950. The Power Sector has been getting 18-20% of the total Public Sector outlay in initial plan periods. Remarkable growth and progress have led to extensive use of electricity in all the sectors of economy in the successive five years plans. Over the years (since 1950) the installed capacity of Power Plants (Utilities) has increased to 89090 MW (31.3.98) from meagre 1713 MW in 1950, registering a 52d fold increase in 48 years. Similarly, the electricity generation increased from about 5.1 billion units to 420 Billion units – 82 fold increase. The per capita consumption of electricity in the country also increased from 15 kWh in 1950 to about 338 kWh in 1997 -98, which is about 23 times. In the field of Rural Electrification and pump set energisation, country has made a tremendous progress. About 85% of the villages have been electrified except far-flung areas in North Eastern states, where it is difficult to extend the grid supply.

1.4 Development of Coal Based Generation

Coal based thermal power stations are presently the mainstay of power development and this is likely to be so in the immediate future also, considering the present status of the projects and various constraints in development of hydro and nuclear power. As per the present estimates, the coal reserves in the country are the order of 202 billion tones with the bulk of the reserves lying in the Eastern Region states of Bihar, Orissa and West Bengal. Of the coal produced about 70% is consumed in the power sector. Presently, about 200 Million Tonnes of coal is consumed yearly in the power sector and this requirement would continue to increase in the coming years. The Planning Commission in the 9th plan document has projected a coal demand in the country for end of 11th plan (2011-12) of 775 MT and production of 672 MT leaving a gap of about 103 MT. It is estimated that the demand for coal by the power sector is likely to be substantially in excess of the production by the end of Ninth and Tenth Plan periods. This demand would need to be met by importing coal and augmenting domestic coal producing capability. Both the options would require special efforts and policy measures. The Government had taken a major step in opening up coal mining to the private sector. It is hoped that substantial private participation would give a boost to the domestic production. Besides quantity, the quality of Indian coal has been a major problem and concern for the power supply industry. With ash content of coals being in the range of 30-50%, the beneficiation of coal assumes special significance. Establishment of washeries therefore assumes a great importance and country has t o address this problem seriously. So far the power sector has relied primarily on railways for coal transportation. However, there are considerable constraints in this area and other modes of transport, viz. shipping, rail-cum-sea route for coastal projects will have to be examined on case to case basis. Keeping in view the problems of fly ash and the high ash content coal, the desirable option would be to develop large pit head coal projects and transmit the power to the load centers. Only Washed Coal should be transported to load centre stations and washery rejects may be utilized through fluidized bed boilers in power stations at the pit head itself.

Chapter 2

WORKING OF THERMAL POWER PLANT

2.1 Diagram of a typical coal fired thermal power station

Figure-2.1

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/PowerStation2.svg/595px-PowerStation2.svg.png

2.2 Block Diagram

Figure-2.2

2.3 Working of Thermal power plant

1.3.1 Feedwater heater

A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feed water reduces the irreversibility 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 introduced back into the steam cycle.

2.3.2 Boiler

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.

2.3.3 Steam condensing

The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases.

2.3.4 Electrical Generator

In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy.

2.3.5 Steam Turbine

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion.

2.4 Advantages

The fuel used is quite cheap.
Less initial cost as compared to other generating plants.
It can be installed at any place irrespective of the existence of coal. The coal can be transported to the site of the plant by rail or road.
It requires less space as compared to Hydro power plants.
Cost of generation is less than that of diesel power plants.

6. They can be located very conveniently near the load centers.

7. Does not require shielding like required in nuclear power plant

8. Unlike nuclear power plants whose power production method is difficult, for thermal power plants it is easy.

9. Transmission costs are reduced as they can be set up near the industry.

10. The portion of steam generated can be used as process steam in different industries.

11. Steam engines and turbines can work under 25%of overload capacity.

12. Able to respond changing loads without difficulty.

2.5 Disadvantages

It pollutes the atmosphere due to production of large amount of smoke and fumes.

2. Large amounts of water are required.

3. Takes long time to be erected and put into action.

4. Maintenance and operating costs are high.

5. With increase in pressure and temperature, the cost of plant increases.

6. Troubles from smoke and heat from the plant, disposal of ash.

Chapter-3

ENVIRONMENTAL IMPACT OF THERMAL POWER STATIONS

Thermal Power Stations in India, where poor quality of coal is used, add to environmental degradation problems through gaseous emissions, particulate matter, fly ash and bottom ash. Growth of manufacturing industries, in public sector as well as in private sector has further aggravated the situation by deteriorating the ambient air quality. Ash content being in abundance in Indian coal, problem of fly ash and bottom ash disposal increase day by day. The fly ash generated in thermal power station causes many hazardous diseases like Asthma, Tuberculosis etc.

3.1 Air pollution

Initially, perceptions of objectionable effects of air pollutants were limited to those easily detected like odour, soiling of surfaces and smoke stacks. Later, it was the concern over long term/chronic effects that led to the identification of six criteria pollutants. These six criteria pollutants are sulphur di-oxide (SO2), Carbon Mono-oxide (CO), Nitrogen oxide (NO2), Ozone (O3), suspended particulates and non-methane hydrocarbons (NMHC) now referred to as volatile organic compounds (VOC). There is substantial evidence linking them to health effects at high concentrations. Three of them namely O3, SO2 and NO2 are also known phytotoxicants (toxic to vegetation). In the later part Lead (Pb) was added to that list.

3.2 Nitrogen Oxide (NOx)

Most of the NOx is emitted as NO which is oxidised to NO2 in the atmosphere. All combustion processes are sources of NOx at the high temperature generated in the combustion process. Formation of NOX may be due to thermal NOx which is the result of oxidation of nitrogen in the air due to fuel NOx which is due to nitrogen present in the fuel. Some of NO2 will be converted to NO3 in the presence of 02. In general, higher the combustion temperature the higher NOx is produced. Some of NOxis oxidised to NO3, an essential ingredient of acid precipitation and fog. In addition, NO2 absorbs visible light and in high concentrations can contribute to a brownish discoloration of the atmosphere.

3.3 Sulphur Oxide

The combustion of sulphur containing fossil fuels, especially coal is the primary source of SOx. About 97 to 99% of SOx emitted from combustion sources is in the form of Sulphur Di-oxide which is a criteria pollutant, the remainder is mostly SO3, which in the presence of atmospheric water is transformed into Sulphuric Acid at higher concentrations, produce deleterious effects on the respiratory system. In addition, SO2 is phytotoxicant.

3.4 Water pollution

Water pollution refers to any change in natural waters that may impair further use of the water, caused by the introduction of organic or inorganic substances or a change in temperature of the water. In thermal power stations the source of water is either river, lake, pond or sea where from water is usually taken. There is possibility of water being contaminated from the source itself. Further contamination or pollution could be added by the pollutants of thermal power plant waste as inorganic or organic compounds.

3.5 Land degradation

The thermal power stations are generally located on the non-forest land and do not involve much Resettlement and Rehabilitation problems. However it's effects due to stack emission etc, on flora and fauna, wild life sanctuaries and human life etc. have to be studied for any adverse effects. One of the serious effects of thermal power stations is land requirement for ash disposal and hazardous elements percolation to ground water through ash disposal in ash ponds. Due to enormous quantity of ash content in India coal, approximately 1 Acre per MW of installed thermal capacity is required for ash disposal. According to the studies carried out by International consultants if this trend continues, by the year 2014 -2015, 1000 sq. km of land should be required for ash disposal only.

3.6 Noise pollution

Some areas inside the plant will have noisy equipments such as crushers, belt conveyors, fans, pumps, milling plant, compressors, boiler, turbine etc. Various measures taken to reduce the noise generation and exposure of workers to high noise levels in the plant area will generally include:

i) Silencers of fans, compressors, steam safety valves etc.

ii) Using noise absorbent materials.

iii) Providing noise barriers for various areas.

iv) Noise proof control rooms.

v) Pro vision of green belt around the plant will further reduce noise levels.

3.7 Technology up gradation:

3.7.1 Clean coal technologies:

Clean coal technologies offer the potential for significant reduction in the environmental emissions when used for power generation. These technologies may be utilized in new as well as existing plants and are therefore, an effective way of reducing emissions in the coal fired generating units. Several of these systems are not only very effective in reducing Sox and NOx emissions but because of their higher efficiencies they also emit lower amount of CO2 per unit of power produced. CCT's can be used to reduce dependence on foreign oil and to make use of a wide variety of coal available. Blending of various grades of raw coal along with beneficiation shall ensure consistency in quality of coal to the utility boilers. This approach assumes greater relevance in case of multiple grades of coals available in different parts of the country and also coals of different qualities being imported by IPPs. Ministry of Environment and Forests vide their notification dated 30th June 1998 had stipulated the use of raw or blended or beneficiated coal with ash content not more than 34% on an annual average basis w. e. f. 1st June 2001. CPCB has constituted a Steering Committee consisting representative from some SEBs, CPCB, Ministry of Coal, Ministry of Power, CEA and World Bank to carry out cost benefit analysis of using clean coal technologies and assess and prioritize technically feasible and economically viable measures to improve coal quality.

3.7.2 Refurbishment of existing thermal power stations:

Continuous deterioration in performance of thermal power stations had been observed during early 80's. Therefore, Renovation and Modernization Schemes(R&M Schemes) were drawn and executed for improving the performance of existing thermal power stations. Pollution control measures in these power stations being a capital-intensive activity, it accounted for major portion-around 40% of Rs. 12 Billion kept for R&M schemes under phase-I. During phase-I, 163 units of 34 thermal power stations were covered. As a result of R&M schemes these achieved 10,000 million units of additional generation per annum against the target of 7000 million units. Encouraged by the results achieved, R&M phase-II programme is presently under progress. Total estimated cost of these works is Rs. 24 Billion. Most of the Electricity Boards or other generating agencies are facing financial constraints to carry out R&M activities. Therefore, this area has to be taken on priority to arrange financial assistance. Several organizations have carried out Energy audits of thermal power plants with a view to suggest measures to improve their operational efficiency and to identify areas having wasteful use of energy. Steps have been suggested to reduce energy losses and their implementation is being monitored vigorously.

Chapter-4

ROLE OF NTPC AND POWER GENERATION

4.1 Overview:

India’s 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 utilisation and coal mining. NTPC ranked 317^th in the ‘2009, Forbes Global 2000’ ranking of the World’s biggest companies. NTPC became a Maharatna company in May, 2010, one of the only four companies to be awarded this status.

The total installed capacity of the company is 33,194 MW with 15 coal based and 7 gas based stations, located across the country. In addition under JVs, 5 stations are coal based & another station uses naptha/LNG as fuel. 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 capacity shall make up nearly 28% of NTPC’s portfolio.

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.

4.2 Ash Utilisation

Gainful and sustainable ash utilization is one of the key concerns at NTPC. The Ash Utilization Division, set up in 1991, strives to derive maximum usage from the vast quantities of ash produced at its coal based stations. The Division proactively formulates policies, plans and programmes for ash utilization. It further monitors the progress in these activities and works for developing new segments of ash utilization. At each station, its own Ash Utilization cell handles ash utilization activities and makes efforts for gainful and sustainable ash utilization.

The quality of fly ash produced at NTPC’s stations is extremely good with respect to fineness, low unburnt carbon and has high pozzolanic activity and conforms to the requirements of IS 3812 – 2003-Pulverized Fuel Ash for use as Pozzolana in Cement, Cement Mortar and Concrete. The fly ash generated at NTPC stations is ideal for use in manufacture of Cement, Concrete, Concrete products, Cellular concrete products, Bricks/blocks/ tiles etc. To facilitate availability of dry ash to end – users, fly ash evacuation and storage system have been set up at coal based stations. Further, at NTPC-Rihand facility for loading fly ash into rail wagons has been provided so that fly ash can be transported in bulk quantity through railway network. Such facility is also being provided at all new upcoming thermal power stations.

As the emphasis on gainful utilization has increased, the usage over the years has also increased. Over the years, the Ash Utilization level from meager 0.3 million tons in 1991 – 1992 has reached to robust 27.61 million tons in 2009-10.

The various segments of ash utilization currently include Cement, Asbestos – Cement products & Concrete manufacturing industries, Land development, Road embankments construction, Ash Dyke Raising, Building Products such as Bricks/ blocks/tiles, Reclamation of coal mine and as a soil amender and source of micro –nutrients in agriculture.

Area wise break-up of utilisation for the year 2009-10 is as under:

Area of Utilisation

Quantity (in Million Tons)

Land Development

7.73

Cement manufacturing

7.20

Ready Mix Concrete and asbestos cement products

0.40

Roads embankments

1.34

Ash Dyke Raising

3.51

Bricks and other building products

2.04

Mine Filling

1.13

Export

0.90

Others

Table-4.1

3.36

Total

27.61

Use of ash in agriculture, as a soil modifier and source of micronutrient has been successfully demonstrated in the farmers’ fields at many of NTPC stations. For this “Show case projects”in association with Agriculture Research Institutes have been carried out in the farmers’ fields. Various crops of different seasons have been grown and harvested and increase in crops yield is given below:

Sl. No.

Name of Crop

Increase in Yields

Wheat

16-22%

Paddy

10-15 %

Sugarcane

20-25%

Banana

25-30%

Maize

Table-4.2

More than 30%

Vegetables

10-15%

To demonstrate use of ash in construction of railway embankment research study was carried out in association with Central Road Research Institute (CRRI), New Delhi. The design of railway embankment developed by CRRI was validated by conducting Centrifuge model tests at IIT, Bombay. Construction of railway embankment of NTPC’s Merry Go-Round (MGR) track for coal transportation is planned at Kahalgaon and Talcher –Kaniha.

Use of fly ash in the manufacture of pre-stressed railway concrete sleeper demonstrated in association with IIT Kanpur. Research Studies also have been taken up to explore use of ash in HDPE and Polypropylene products.

From time to time, NTPC Ash Utilization Division is bringing out literature on use of ash in various applications in the form of books & promotional brochures and documentary films to create awareness among the prospective users & entrepreneurs for use of ash.

Figure-4.1

http://www.ntpc.co.in/images/content/about_us/organisation/growth_chart.jpg

In October 2004, NTPC launched its Initial Public Offering (IPO) consisting of 5.25% as fresh issue and 5.25% as offer for sale by Government of India. NTPC thus became a listed company in November 2004 with the Government holding 89.5% of the equity share capital. In February 2010, the Shareholding of Government of India was reduced from 89.5% to 84.5% through Further Public Offer. The rest is held by Institutional Investors and the Public.

http://www.ntpc.co.in/images/content/about_us/organisation/overviewchart.jpg

At NTPC, People before Plant Load Factor is the mantra that guides all HR related policies. NTPC has been awarded No.1, Best Workplace in India among large organisations and the best PSU for the year 2009, by the Great Places to Work Institute, India Chapter in collaboration with The Economic Times.

Figure 4.2

The concept of Corporate Social Responsibility is deeply ingrained in NTPC's culture. Through its expansive CSR initiatives, NTPC strives to develop mutual trust with the communities that surround its power stations.

4.3 CenPEEP - Centre for Power Efficiency & Environmental Protection

Towards the reduction of Greenhouse Gas (GHG) emission from Indian thermal power plants, NTPC has been promoting and deploying efficient power generation technologies and practices from design stage to operation stage and building local institutional capacities for continuously striving for eco-friendly technologies.

NTPC established Centre for Power Efficiency & Environmental Protection (CenPEEP) in collaboration with USAID with a mandate to reduce GHG emissions per unit of electricity generated by improving the overall performance of coal-fired power plants. The centre functions as a resource centre for acquisition, demonstration and dissemination of state-of-the-art technologies and practices for performance improvement of coal fired power plants for the entire power sector of India.

Win-win Approach for Global Climate Change

NTPC has adopted a win-win strategy at CenPEEP by achieving synergy between environmental concerns and utility needs. We have initiated the Comprehensive Performance Optimisation Programme thereby successfully balancing the dual objectives of reducing carbon-di-oxide emissions that contribute to climate change and facilitating higher efficiency of power generation.

Figure 4.3

http://www.ntpc.co.in/images/content/environment/canPEEP/chart.jpg

Under NTPC’s effort for betterment of Indian Power Sector, CenPEEP is also assisting various state electricity utilities in India by demonstration and dissemination of improved technologies and practices. To increase outreach to SEBs, 2 regional centres of CenPEEP have also been established in the Northern Region (Lucknow) and Eastern Region (Patna).This approach has brought significant benefits to the power plants and helped in the reduction of emissions.

4.4 Technological Interventions

For greater acceptability and assimilation of eco-friendly technologies and practices, methodology of ‘Technology Acquisition, Demonstration and Dissemination’ has been adopted. Focus has been on low cost high benefit options. Also involve people from local power stations during demonstration and widespread dissemination.

Methodology & Reach

Boiler Performance Optimisation	Predictive maintenance system and technologies for diagnostics
Best practices for air-preheater, etc. condenser water pressure cleaner	Reliability Centred Maintenance(RCM)
Condenser helium leak detection	Thermodynamic modeling: A tool for performance analysis
Steam turbine performance assessment & optimisation	Thermal audit for:- accurate assessment of degradations
Real time measurements & balancing of air-fuel ratio	Risk Evaluation & Prioritisation (REAP)
Cooling tower, condenser performance optimisation	New overhaul practices

Table 4.3

4.5 Afforestation:

Maintenance of ecological balance and a perfect environment has been of utmost importance at NTPC. Environment planning and preservation is an integral part of its project activities. NTPC undertakes afforestation programmes covering vast tracts of land in and around its projects in a concerted bid to counter the growing ecological threat.

The crucial need for conservation and restoration of the degraded ecosystem and preservation of genetic resources of the country led to the enactment of the ‘Wild Life Protection Act’ (1974) and ‘Forest Act’ (1980) in addition to legal acts of air, water and environment.

Figure 4.4

http://www.ntpc.co.in/images/content/environment/aforestation/img_1.jpg

4.6 NTPC's Approach:

It has been possible to achieve a satisfactory combination of environmental quality and techno-economics through determined efforts at NTPC. Continuous vigilance is maintained to minimise pollution. This is over and above the other environment management programmes that start simultaneously with start of construction activities.

The appropriate afforestation programme for plant, township, green-belt and other sites are designed according to the geographical features. Species are selected on the basis of their adaptability and grouped with local representatives. The growth characteristics, flowering pattern and canopy (spreading nature) are evaluated in their distribution over these sites of afforestation. These considerations not only contribute to the aesthetics but also go a long way in serving as ‘Sinks’ for the pollutant emission of the power plant. At times, they even combat pollution from other industries in the surrounding area.

NTPC has developed independent Horticulture Department at its projects headed by experienced horticulture officers / supervisors.

Saving existing trees, planting right at the beginning of construction phase, preservation of trees and advice from State Forest Departments and agricultural universities are a few general guidelines followed by NTPC.

Chapter-5

ULTRA MEGA POWER PROJECTS

The UMPPs are seen as an expansion of the MPP (Mega Power Projects) projects that the Government of India undertook in the 1990s, but met with limited success. The Ministry of Power, in association with the Central Electricity Authority and Power Finance Corporation Ltd., has launched an initiative for the development of coal-based UMPP's in India. These projects will be awarded to developers on the basis of competitive bidding.

The Government has a target of “Power for All” by 2012. To meet the capacity addition targets required to achieve this objective, the Ministry of Power launched an initiative facilitating the development of coal-based UMPPs. Development of large power projects can result in cheaper power through economies of scale. Recognizing this, the Government envisages a series of projects of at least 4,000 megawatts (MW) each. These projects will be awarded to developers identified and selected through international competitive tariff-based bidding processes. The projects will be developed on a build-own-operate basis. Based on supercritical technology, these projects are also expected to be more environment friendly than conventional subcritical generating units. India will be dependent upon coal as a fuel for a large portion of its power generation for the foreseeable future as it has no other practical alternatives. Thus the issue is how to generate power from coal as cleanly as possible. The Project will be one of the new generations of cleaner coal projects and thus merits ADB's active support. The Project will contribute significantly to reducing power shortages in the country.

5.1 The Sasan Ultra Mega Power Project Reliance:

Reliance Power’s Sasan UMPP is a 3,960 MW (6 units of 660 MW each) super-critical technology based pit-head coal-fired power generating plant at Sasan, in Madhya Pradesh, India. this is the first of the three UMPPs awarded to Reliance Power. It involves development of associated captive coal mines allotted to the Company, which ensures fuel security. Sasan Power has entered into a 25-year Power Purchase Agreement (PPA) with off-takers of power for its entire capacity at a competitive tariff of ` 1.19 per kWh. The Project would supply power to 14 off-takers in seven states benefitting over 35 crore Indians. The estimated Project Cost of the Power Project (excluding coal mines) is about 16,000 crore. The construction of the Project is progressing at a fast pace with the expected commissioning in 2012-13. Reliance Power

Reliance Power Limited, a part of Reliance Anil Dhirubhai Ambani Group, is India's leading private sector power generation Company. Reliance Power is implementing power projects with aggregate capacity of over 37,000 MW, by far the largest development portfolio in the country. The Company also has the largest coal reserves in the private sector estimated at more than two billion tones

5.2 Ultra Mega Power Project Tata Power

The Mundra UMPP was awarded to Tata Power and as per the share purchase agreement Tata Power acquired CGPL on 22 April 2007.The project will have five units of 800 MW each, generating a total of 4,000 MW using supercritical technology and 40,000 MT /day imported coal.Power will be evacuated through six 400kV lines, to be installed by Power Grid, to ultimately benefit the States of Gujarat, Maharastra, Punjab, Haryana and Rajasthan

Figure 5.1

5.3 Ultra Mega Power Project NTPC

The 4,000-Mw Kudagi Ultra Mega Power Plant proposed to be set up by the National Thermal Power Corporation (NTPC) at Kudagi in Basavana Bagewadi taluk of Bijapur district,

Figure 5.2

Chapter-6

ADVANCED TECHNOLOGIES OF PREVENTIVE MAINTENANCE FOR

THERMAL POWER PLANTS

6.1 Overview:

Although thermal power generating facilities are aging, flexible operation in response to changes in the demand for electrical power is required. To extend the life and manage the maintenance of those facilities, advanced preventive maintenance technology is important. For that reason, Hitachi has been grappling with nondestructive inspection, life assessment technology, rationalization technology for scheduled inspections of the boilers, steam turbines, gas turbines and other machinery used in thermal power generation to strengthen preventive maintenance and increase the efficiency of maintenance. Recently, they have been developing products and services for advanced support for maintenance and preservation through the use of IT (information technology) and network technology, going beyond what has previously been available.

6.2 Introduction:

In recent years, startup and shutdown operations have become frequent in aging thermal power generation facilities, and preventive maintenance technology has steadily been increasing in importance from the viewpoints of extending the scheduled inspection interval and strengthening the independent management of facilities. Furthermore, concerning preservation of the global environment as well, there is also a strong demand for the reduction of CO2 emissions through improved generation efficiency and fuel conversion in existing facilities.

Under such circumstances, Hitachi is going beyond the application of new technology that has been developed for new power plants to old facilities, and has taken up the challenge of developing our own preventive maintenance technology. Together with these advanced technologies and products, Hitachi is making use of IT, which has developed rapidly in recent years, to provide global services that contribute to life-cycle cost minimization for power generation facilities (see Fig. 1).

Figure 6.1

6.3 Application of IT to Preventive

Maintenance of Thermal Power Plants:

Hitachi is proceeding to add intelligence in a wide range of fields by making use of IT and the proprietary knowledge we have accumulated in various industrial areas with the objective of being the customers’ “Best Solutions Partner” by offering new solutions.

In the field of preventive maintenance for thermal power plants, too, they have taken up the challenge of using IT and network technology to provide services for the support of advanced maintenance and preservation that go beyond what has been available to the customer in the past.

With the increasingly severe demands on the operation of aging thermal power plants, typified by extension of the period for scheduled inspections and DSS (daily start-up and shut-down) operations, there is increasing need to know the quantitative state of the facilities, such as by monitoring operation at times of transition and knowing the deterioration state of equipment, in addition to the regular monitoring of operation. There is also a demand for the provision of performance evaluation technology for life-cycle cost minimization, as well as the provision of operation methods that use such technology to optimize efficiency and the provision of operation data management services. To meet that demand, Hitachi is developing services which make use of IT, such as plant monitoring services and engineering services.

6.4 Preventive Maintenance Technology for Boilers Application of the Latest Development Technology:

The conventional techniques for nondestructive inspection of boiler materials and parts include PT (liquid penetrant testing), MT (magnetic particle testing), and UT (ultrasonic testing), among others.

These types of inspection, however, have problems such as:

(1) difficulty of inspecting narrow gapped areas,

(2) requiring a large amount of associated work, and

(3) difficulty of lifetime diagnosis or can predict quantitative damage progress.

To cope with these problems, Hitachi has been developing various kinds of scheduled inspection rationalization technology to achieve lower-cost, timely inspection by reducing the preparation work and to achieve fast, highly accurate inspection by employing advanced inspection equipment without direct contact. The main diagnostic points and diagnosis technology are shown in Fig. 3. These rationalized technologies are already being applied in actual plants.

Figure 6.2

Of these technologies, ELFOSS UT (electronic focus sector scan ultrasonic testing), which can evaluate internal defects in the welds of main pipes, is described below:

ELFOSS UT can evaluate defects contained in welds and in narrow nozzle stubs by electronic focusing and sector scanning techniques. A major feature of this device is that the scanning range of the UT probe is smaller than that used in the conventional UT method, so the defect size and location can be determined accurately. The results of ELFOSS UT inspection of a plate (100-mm thick) butt weld that contains an artificial defect are shown in Fig. 4. The defect detected by the nondestructive method matches well with the defect as confirmed by cross-section examination. With such an excellent defect detection capability, this equipment is being applied to precise inspection of important areas, such as the welds of main pipes.

6.5 Scheduled Inspection Rationalization Technology:

The various types of nondestructive inspection equipment shown in Fig. 3 are all capable of quantitative evaluation of defects, and can also be called rationalized technologies with respect to shortening inspection time for schedule inspections.

In addition to such higher performance of the inspection equipment itself, rationalization technology such as for shortening the preparation time for inspection is also desired.

For example, in the furnace of coal-fired boilers, fused ash adheres to places such as the bends in the heat exchange pipes that are suspended from the top of the furnace. Such ash may grow to form hard clinkers. Because it is very dangerous if those clinkers fall inside the furnace, they should be removed before installing the scaffolding and performing the inspection and repair work at the time of scheduled inspections. The removal of the clinkers in this way requires much time and labor. For that reason, hitachi turned attention to WJ (water jet) technology, and developed a special nozzle that produces several times the force of the conventional nozzle. Using this nozzle reduces the time required for clinker removal significantly, and the time from the shutdown of a plant to the beginning of inspection and repair can be greatly reduced.

Figure 6.3

6.6 Preventive Maintenance Technology for Steam

Turbines:

For high-temperature components of aging steam turbines, accurate preventive maintenance and extension of machine life is becoming established.On the other hand, for low-temperature components, of which low-pressure turbines are a typical example, damage related to corrosion has been appearing in recent years. In most of those cases, corrosion fatigue cracking or SCC (stress corrosion cracking) is seen in the severely corrosive phase transition zone environment. To deal with these problems, hitachi establishing highly accurate lifetime evaluation technology derived from an understanding of actual operation in service. That technology is based on analysis of the vibratory response in grouped blades in the low pressure stage and accumulating data on the occurrence and growth of corrosion pitting in the actual environment. As a result, it is trying to maintain the reliability of low-temperature parts in a corrosive environment by recommending the overhaul of low-pressure turbines that have been in service for 20 years or more by removal of the bucket.

Figure 6.4

6.7 Development of Scheduled Inspection Technology for Improving In Efficiency:

With the continuing relaxation of regulation, there is an even stronger demand for improvement in the operating efficiency of facilities as well as the lowering of maintenance costs. For those reasons, we are endeavoring to raise the efficiency of work involved in the scheduled inspection of turbines and to develop various types of technology for increasing efficiency and conserving energy. The technology for rationalizing scheduled inspection work not only improves that work directly, but also includes technologies, such as facility diagnosis technology, that minimizes that work and asset management technology that in turn increases the efficiency of managing the scheduled inspection data.

6.7.1 Rationalization Technology For Scheduled

Inspections:

To shorten the scheduled inspection process, we have developed tapered sleeve type bolting equipment for the bucket coupling and oil flushing reduction equipment. The tapered sleeve type bolting equipment allows smooth bolt extraction, so the bolt loosening time can be reduced to half a day per coupling. Previously, five to seven days were required to flush the oil for cleaning the bearings and bearing box after completing the assembly of the turbine and generator. The oil flushing reduction equipment, however, achieved results that fully satisfy the specified bearing oil cleanness requirement in only three days, as well as reducing the test operation time.

6.7.2 Facility Diagnosis Technology :

For facility diagnosis, we developed leak diagnosis technology that makes use of AE (acoustic emission). Up to now, AE diagnosis has been applied to abnormality detection in rotating parts such as turbines and pumps. Now we have developed technology for applying this method to steam leaks in stop valves as well. An application example is shown in Fig. 5.

6.7.3 Asset Management Technology:

As an asset management technology, we have developed a scheduled inspection record and history management application system. Rapid and paperless recording of data from the time of measurement to data management is made possible by using a network to connect the inspection site and the persons responsible for data approval and management. This inspection recording application is linked to a history management system, and serves to provide data for the history management of assets. In this way, the various types of information from the inspections is data based for each asset so that the deterioration trend of each asset can be known. Furthermore, data mining is done easily by time series of the maintenance data for each asset or by phenomenon. A sample window from the turbine history management application is shown in Fig. 6. Introducing the various types of rationalization equipment that have been developed can shorten the standard process for a 600-MW turbine to about five days and a 10 to 15% saving in energy can be expected.

Figure 6.5

6.8 Preventive Maintenance Technology for Gas

Turbines:

The load conditions are very severe for gas turbines, which use high-temperature combustion gases as the working fluid. For that reason, differently from steam turbines, the hot gas path components that are placed in the path of the combustion gases have a relatively short operating time and are repaired repeatedly during the course of use. Maintenance costs for repair, reconditioning and part updating are a large proportion of the cost of generating electricity, so the advancement of preventive maintenance technology is important in terms of economy as well as reliability.

6.9 Lifetime Management and Repair of Hot Gas Path

Components:

The life of hot gas path components is shortened by creep, abrasion, oxidation and other such damage that is related to operating time and by damage that occurs as the result of repeated startups and shutdowns, such as low-cycle fatigue. Accordingly, lifetime management employs the equivalent operating time method, which takes into account the effects of the number of startups shutdowns and sudden changes in load, etc. as well as the actual operating time. When the equivalent operating time reaches the specified lifetime, that component is considered to have reached the end of its operating life. Concerning the hot gas path components, if the inspection result exceeds the judgement criteria, the component is repaired. See Table 1 for a description of the repairs. Of those, the latest repair technology that is currently being used in actual plants is described below.

6.10 Gas Turbine Bucket Recoating Repair:

Gas turbine buckets are subjected to severe conditions of centrifugal force and high thermal stress load in the high-temperature and high-pressure combustion gases. For that reason, Ni-based super-alloys are used and an oxidation resistance coating is applied to the bucket surface to protect the base material. With long-term use of the buckets, the coating suffers damage by deterioration, so it is necessary to strip the old coating and recoat the buckets before the base material is damaged. Measures are also taken against erosion of the bucket tips by high-temperature oxidation. Hot tearing from welding heat flux usually occurs in Ni-based super-alloys with high Ti or Al content, so it is a difficult material to weld. In recent years, however, low-current welding methods have been developed, so repair by build-up welding has become practical for the low-stress bucket tips.

6.11 Gas Turbine Nozzle Blade Diffusion Brazing Repair:

Gas turbine nozzle blades suffer thermal fatigue cracking due the thermal stress caused by start-up and shut-down. Those cracks must be repaired by welding during the course of nozzle blade use. There is a tendency for multiple thermal stress cracks to appear over a wide area of the nozzle blades, so repairing them takes a great deal of time and effort. Furthermore, deformation of the nozzle blades occurs in proportion to the amount of heat applied during the welding. Diffusion brazing repair avoids that problem by using a brazing filler metal that has about the same composition as the base metal, but with a low melting point metal added. This method involves cleaning the surfaces of the cracks, flowing the filler metal into the cracks and then diffusing the filler metal into the blade metal with a heat treatment. This method reduces labor for the repair and prevents deformation of the blades. By using both welding repair and diffusion brazing repair, we are reducing labor and extending the life of nozzle blades.

Comparison

Table- 6.1

CONCLUSION

There is a huge increase in demand for power, due to population increase, economic development, rapid industrialization and growth of IT services industry. However shortage of power is not only inconveniencing the citizens of the country but also adversely affecting the industrial production and studies of the students during the examination time
The possibility of increasing power production through hydro-electric route is very limited. There is very huge resistance to build nuclear power plants due to the risk of radiation and its adverse effect on the population around the power plants. The recent tragedy at Fukushima in Japan has only complicated the nuclear energy situation.
The final conclusions of this paper are-

I. Presently India has substantial thermal power production infrastructure. The technological innovations introduced by Hitachi as explained above should be adopted by the various thermal plants.

II. NTPC is doing a yeoman service in the field of thermal power in India. All encouragement should be given to it, to not only increase the capacity but also the efficiency of power production. Government of India should provide it with adequate capital support.

III. The recent decision of the Government of India to award UMPP to various private sector parties is a very welcome decision. More and more locations suitable for UMPP should be identified by the Government and the projects should be awarded to the private sector expeditiously.

REFERENCES

E-BOOKS & JOURNALS

NTPC Guide for Users of Coal Ash
Fly Ash Bricks – Modern Building Material; Towards Cleaner Environment
Fly Ash for Cement Concrete – A Resource for High Strength and Durability of Structure at Lower Cost
Ritish Electricity International (1991). Modern Power Station Practice: incorporating modern power system practice (3rd Edition (12 volume set) ed). Pergamon. ISBN 0-08-040510-23.

WEB LINKS

www.air-dispersion.com
www.ntpc.co.in
www.emt-india.net/PowerPlantComponent
www.Sciencedirect.com.

Pavan Paga

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Train maintenance

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SEMINAR TOPIC- Thermal Power Plant

2.3.3 Steam condensing

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