Study of Combined Gas Cycle Power Plant
and Modernization of Siemens V94.2
A report based on internship at NTPC,
Faridabad
Submitted by: Bhushan Maskay
Department of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY, GUWAHATI
GUWAHATI- 781039, ASSAM
Preface
This report is a summary of the study done at NTPC Limited (Formerly National Thermal Power Corporation) based on 2 months (June-July 2010) training at its gas based power plant in Faridabad. During the project I was introduced to the various departments and their workings in the plant. I was also introduced to the various components involved in the generation of electricity, their running parameters and the necessary precautions taken to prevent their damage. During this training I enhanced my engineering knowledge as I developed an entire concept of combined gas cycle power generation from scratch.
There are three parts of this report: (I) Introduction to NTPC (II) Faridabad Gas based power plant (III) Mechanical Design .
Part I covers the history of NTPC and its growth through the years. It also gives an insight into its upcoming projects, joint ventures and other key data related to the company.
Part II introduces the details of the Faridabad plant. It provides the particulars of the components used and the procedure used in power generation. It also briefs on the working of the major departments of the plant and their workings.
Part III deals mainly with the gas turbine design, and also includes the latest modernization products from Siemens V94.2 (also known as SGT5-2000E).
Acknowledgement
I owe thanks to a great many people who helped and supported me during the training period at NTPC.
My deepest thanks to Mr. Niranjan for guiding the training and arranging the lectures timely. I express my thanks to Mr. K K Sharma (Sr Manager, Chem.), Mr. S K Bhargava (MTP), Mr. V K Garg(Operations), Mr. Manoj Agarwal (Mechanical Maintenance), Mr. Rohit Sharma (C & I) and Mr. S K Baliyan (Electrical Maintenance).
I extend my gratitude to Mr. Amit Tyagi (Mechanical Maintenance) for his guidance and support during the period.
Thanks and appreciation to all the helpful people at NTPC Limited for their support. I would also thank my institution and my faculty members for developing in me a basic understanding of the concepts without which this report would have been a distant reality.
Index
1. Part I: Introduction to NTPC 1.1. About the company 1.2. Evolution of NTPC 1.3. NTPC group 1.4. Power Generation 1.5. NTPC Operations 1.6. Turnaround Capability 1.7. NTPC Strategies 1.8. International Cell
1.9. Ecological Monitoring Programme 2. Part II: Faridabad gas based power plant
2.1. Overview
2.2. Combined Cycle Gas Turbine (CCGT) power plant 2.3. Water treatment
2.3.1. Pre-Treatment(PT) plant 2.3.2. De-Mineralization(DM) plant 2.4. Components
2.4.1. Air Filter
2.4.2. Compressor-Gas Turbine- Generator 2.4.3. Diverter-Damper
2.4.4. Heat Recovery Steam Generator (HRSG) 2.4.5. Steam Turbine Generator
2.4.6. Main Control Room (MCR) 2.4.7. Cooling tower
2.5. Switchyard
2.6. Major Departments
2.6.1. Human resources (HR)
2.6.2. Maintenance Planning (MTP)
2.6.3. Operation & Maintenance: Mechanical (O&M- MM) 2.6.4. Operation & Maintenance: Electrical (O&M- EMD)
2.6.5. Operation & Maintenance: Control & Instrumentation (O&M- C&I) 2.6.6. Operation & Maintenance: Chemical (O&M-Chem)
3. Part III: Gas Turbine Design and Modernisation 3.1. Introduction to Siemens V94.2
3.2. Auxiliaries
3.2.1. Lube oil system
3.2.2. Lube oil cooling system 3.2.3. Fuel oil system
3.2.4. Purge water system 3.2.5. Hydraulic system 3.2.6. Ignition Gas system 3.2.7. Filter Housing 3.2.8. Turbine
3.2.9. Generator
3.2.10. Generator cooling system 3.2.11. Exhaust
3.3. Overview of GT Modernistation Products
3.3.1. Turbine Inlet Temperature Upgrade(TT1+) and Extended Maintenance interval (41 MAC)
3.3.2. Compressor Mass Flow Upgrade(CMF+)
3.3.3. Dry- Low- NOX (DLN) Upgrade using HR3-burner
3.3.4. Performance Boost with Wet Compression (WetC) 3.3.5. Humidity I & C Module for GT control system 3.3.6. Fuel Conversion Upgrade
3.3.7. Siemens innovative 3-D Turbine Blades & vanes 3.3.8. Lifetime Extension
3.4. SGT5-2000E adjustment to site conditions 3.5. Configuration after Modernization
1.1 About the company
Corporate Vision:
“A world class integrated power major, powering India’s growth, with increasing global presence”
Corporate Mission:
“Develop and provide reliable power, related products and services at competitive prices, integrating multiple energy sources with innovative and eco-friendly technologies and contribute to society.
”
Core Values: BCOMIT
B-Business Ethics C-Customer Focus
O-Organizational & Professional pride M-Mutual Respect and Trust
I- Innovation & Speed
T-Total quality for Excellence
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 ranked 317th in the 2009’s Forbes Global Ranking of the World’s biggest companies.
The total installed capacity of the company is 31,704 MW (including JVs) with 15 coal based and 7 gas based stations, located across the country. In addition under JVs, 3 stations are coal based & another station uses naptha/LNG as fuel. By 2017, the power generation portfolio is expected to have a diversified fuel mix with coal based capacity of around 53000 MW, 10000 MW through gas, 9000 MW through Hydro generation, about 2000 MW from nuclear sources and around 1000 MW from Renewable Energy Sources (RES). NTPC has adopted a multi-pronged growth strategy which includes capacity addition through green field projects, expansion of existing stations, joint ventures, subsidiaries and takeover of stations.
NTPC has been operating its plants at high efficiency levels. Although the company has 18.10% of the total national capacity it contributes 28.60% of total power generation due to its focus on high efficiency.
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. The rest is held by Institutional Investors and the Public. The issue was a resounding success. NTPC is among the largest five companies in India in terms of market capitalization.
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.
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.
1.2 Evolution of NTPC
· 1975
o Incorporated on November 7.
· 1976
o On December 8, the Government of India cleared NTPC's first pithead super thermal power project at Singrauli in Uttar Pradesh.
o The authorised share capital of the Company was Rs. 125 crore.
· 1977
o NTPC acquired the first patch of land at Singrauli in September.
o The first major contract of Rs. 57.5 million was awarded for site leveling work at Singrauli in June.
· 1978
o Implementation of Korba and Ramagundam Projects cleared by the Government of India in January and February respectively.
o Late Shri Morarji Desai, the then Prime Minister of India, laid the foundation stone for Ramagundam Project on November 14th
o Construction of the first transmission network Singrauli-Kobra-Kanpur of 400 KV system started
· 1979
o Government of India approved the implementation of Farakka Project in March
o The authorised share capital of the Company rose from Rs.125 crore to Rs. 300 crore
· 1980
o Former Soviet Union offered to assist in setting up of power stations. Vidhayachal was identified as the first project for such assistance.
o The authorized share capital was raised from Rs. 300 crore to Rs. 800 crore in June.
· 1981
o Farakka Super Thermal Power Project in West Bengal was the fourth among the first series of four super thermal power projects taken up by NTPC. On December 29, late Smt. Indira Gandhi, the then Prime Minister of India, laid the foundation stone for the Project.
o On December 25, the fifth and last unit of 210 MW at Badarpur Thermal Power Station was synchronised by NTPC, marking the completion of the 720 MW project
· 1982
o The first 200MW unit at Singrauli was commissioned
o The first direct foreign currency borrowing for NTPC- a consortium of foreign banks led by Standard Chartered Merchant Bank extended a loan of GBP 298.41 million for the Rihand project.
o Power Management Institute, Delhi, a centre for education established. o On November 12, Late Smt. Indira Gandhi, the then Prime Minister of
India laid the foundation stone for Vindhyachal Super Thermal Power Project in Madhya Pradesh.
· 1983
o On March 1, the first 200 MW unit of Korba Super Thermal Power Project was commissioned in a record time of 48 months after the placement of order for the main plant equipment
o Another significant achievement was the supply of uninterrupted power from Badarpur during Asian Games and Non-Aligned Meet held at Delhi.
o Ramagundam became operational on November 26 by commissioning its first 200 MW Unit.
o In the very first year of its commercial operation, NTPC earned a profit of Rs. 4.51 crore in the financial year 1982-83
· 1984
o The transmission line based on HVDC (High Voltage Direct Current) technology, commissioned for power transmission from Rihand to Delhi. o Singrauli project received a World Bank loan of USD 150 million through
the Government of India · 1985
o This year marked the completion of a decade (1975-1985) of NTPC's existence. NTPC achieved a generating capacity of 2200 MW by commissioning 11 units of 200 MW each at its various projects in the country.
o In December '85, the Government of India approved the setting up of three gas-based combined-cycle projects by NTPC at Kawas in Gujrat, Auraiya in Uttar Pradesh and Anta in Rajasthan. For these projects, the World Bank agreed to provide US$ 485 million, which was the largest single loan in the history of the bank.
· 1986
o Synchronisation of its first 500 MW unit at Singrauli.
o NTPC launched its maiden public issue of Bonds and raised a total of Rs. 163.37 crore. This issue was over-subscribed by 63 percent.
· 1987
o Crossed the 5000 MW installed capacity mark.
o Korba also entered the 500 MW phase by synchronizing its first 500 MW unit on May 31
· 1988
o Rihand entered the Operational phase by commissioning its first 500 MW unit on March 31.
o The first 500 MW unit of Ramagundam was commissioned on June 26.
· 1989
o Consultancy division launched.
o First unit (88 MW) of first gas based combined cycle power plant at Anta, Rajasthan commissioned
· 1990
o Total installed capacity crossed 10000 MW · 1991
o Vindhyachal recorded completion of stage I activities by synchronising its sixth and last 210 MW unit in February.
o The first unit of NCPP (Dadri) was commissioned on December 21.
· 1992
o Acquisition by the Company of Feroze Gandhi Unchahar Thermal Power Station (2x210MW) from Uttar Pradesh Rajya Vidyut Utpadan Nigam of Uttar Pradesh.
o Pursuant to legislation by the Parliament of India, the transmission systems owned by the company was transferred to Power Grid Corporation of India Limited.
· 1993
o For the first time, IBRD extended direct loan of USD 400 million under time slice concept for its projects.
· 1994
o Crossed 15000 MW of installed capacity.
o Declared a dividend of Rs. 65 crore for the first time.
o Jhanor-Gandhar (Gujarat) becomes the first thermal power station to have commissioned an integrated Liquid Waste Treatment Plant (LWTP)
· 1995
o NTPC celebrated 20 years (1975-1995) of its existence. A new logo was adopted.
o On June 3rd, NTPC formally took over the 460 MW Talcher Thermal Power Station from Orissa State Electricity Board
o On July 25th, the new campus of Power Management Institute (PMI) was inaugurated.
· 1996
o Continuous running of sixth unit (210 MW) of Ramagundam for 406 days for the first time in India.
o PLF of Talcher Thermal reached 43.7 % from 18.7 % at the time of takeover
· 1997
o Identified by the GOI as one of the Navratna public sector undertakings o Achieved 100 billion units generation in one year.
o A consortium of foreign banks led by Sumitomo Bank, Hong Kong extended foreign currency loan of 5 billion Japanese Yen for the first time without GOI guarantee.
· 1998
o Commissioned the first Naphtha based plant at Kayamkulam with a capacity of 350 MW
· 1999
o Dadri Thermal Power Project, Uttar Pradesh adjudged the best in India with a PLF of 96.12%
o Dadri, Uttar Pradesh certified with ISO-14001 on October 7"" · 2000
o Commenced construction of a first hydro-electric power project of 800MW capacity in Himachal Pradesh
· 2001
o Main plant turnkey package of Rihand Stage-II (2x500MW) and Ramagundam Stage-Ill (IX 500 MW) were awarded to BHEL in August · 2002
o Three wholly owned subsidiaries of NTPC viz. NTPC Electric Supply Company Limited, NTPC Hydro Limited and NTPC Vidyut Vyapar Nigam Limited incorporated
o Crossed the 20000 MW installed capacity mark
· 2003
o Raised funds through bonds (Series Xlllth & XlVth) for prepayment of high cost GOI loans
· 2004
o Awarded contract for the first Super Critical Thermal Power Plant at Sipat NTPC's Feroze Gandhi Unchahar Thermal station achieved a record PLF of 87.43% in current year, up from 18.02% in February' 92 when it was taken over by NTPC
o LIC extended credit facility of Rs.70 billion. Rs.40 billion was in the form of unsecured loans and Rs.30 billion in the form of bonds
o NTPC made its debut issue of euro bonds amounting to USD 200 million in the international market
· 2005
o NTPC received the International Project Management Award, 2005 for its Simhadri project at the International Project Management Association World Congress. NTPC became the only Asian Company to receive this award
o NTPC was ranked as the Third 'Great Place to work for in India' for second time in succession by a survey conducted by Grow Talent and Business World 2005.
o The Company's name changed to NTPC Ltd.
· 2006
o For the fourth consecutive year, NTPC continued to realize 100% of current bills
o On June, 1, the Badarpur Thermal Power Station with an installed capacity of 705 MW was transferred to NTPC by the Government of India
o Another 740 MW was added through its Joint Venture, Ratnagiri Gas and Power Private Limited, Dabhol. Thus taking installed capacity of the NTPC group to 27904 MW
o MOA with Govt. of Sri Lanka and Ceylon Electricity Board for development of 2 x 250 MW Coal based power project at Trincomalee in Sri Lanka
o Energy Technology Centre set up with the mandate of being a world class research institute
· 2007
o Ministry of Coal, Government of India granted in-principle approval for allocation of a new coal block, namely, Chhati Bariatu South to NTPC, subject to the conditions stipulated in the approval letter. The share of reserves was indicated as 354 million tonnes
o Tripartite agreement signed with the Government of Assam, Assam Power Generating Co. Ltd., and NTPC for transfer of existing plant at Bongaigaon and to set up a new plant of 750 MW with 3 units of 250 MW each
o 765 KV switchyard transmission system energised at Sipat, the largest in the country
o MOU signed between NTPC and Ministry of Energy, Federal Government of Nigeria(FGN) for Energy cooperation
o Vindhyachal Super Thermal Power Project became the largest power station in the country with an installed capacity of 3260 MW
· 2008
o Joint Venture Company under the name "National Power Exchange Limited" was incorporated on 11th December 2008 with NHPC Ltd., PFC Ltd., and TCS Ltd., to operate Power Exchange at national level
o NTPC was ranked Number 1 in the 'Best Work places for Large Organisations' and Number 8 overall for the year 2008 by Great Places to Work Institute's, India chapter in collaboration with the Economic Times
· 2009
o 500 MW Unit VI of Sipat brought under commercial generation
o NTPC has achieved the highest ever single day generation of 655.22 MUs on 2nd March, 2009 with highest ever single day coal based generation of 579.02 MUs
·
2010o
Installed capacity reaches 31,704 MW (including 2864 MW under JVs). o 17,830 MW under construction at 17 locations.o New national benchmark: Dadri Unit-5 (490 MW) begins commercial operation in 39 months from zero date.
o Generation increased by nearly 6% to 218.84 BUs compared to 3% generation growth achieved in 2008-09; Exceeded the MoU ‘Excellent’ target of 217 BUs.
1.3 NTPC Group
· One of the three largest Indian companies with market cap of Rs.1778 billion · Ranks 126th on the basis of market Cap globally (Forbes 2009 data)
· Has a net worth of Rs. 574 billion · Owns total assets of Rs. 1052 billion
Subsidiaries(6)
Generation
NTPC Hydro Ltd.
(100%)
Kanti Bijlee
Utpadan Nigam
Ltd. (51%)
Bhartiya Rail
Bijlee Company
Ltd. (74%)
Pipavav Power
Development Co
Ltd (100%)*
Services
NTPC Electric
Supply Company
Ltd. (100%)
Power Trading
`NTPC Vidyut
Vyapar Nigam
Ltd. (100%)
Joint Ventures (15) Generation Aravali Power Company Pvt Ltd (50%) NTPC Tamil Nadu Energy Company Ltd (50%) Nabinagar Power Generating Company Pvt. Ltd (50%)
Meja Urja Nigam Pvt. Ltd (50%)
NTPC SAIL Power Company Pvt Ltd
(50%)
Ratnagiri Gas and Power Pvt Ltd (28.33%) Services Utility Powertech Ltd (50%) NTPC Alstom Power Services Pvt Ltd (50%)
National High Power Test Laboratory Pvt Ltd (25%) Equipment Manufacturing NTPC BHEL Power Projects Pvt Ltd (50%) BF NTPC Energy Systems Ltd (49%) Transformers and Electricals Kerala Ltd.(44.6%) Coal Acquisition International Coal Ventures Pvt. Ltd (14.29%) NTPC SCCL Global Ventures Pvt Ltd (50%) Power Trading `National Power Exchange Ltd (16.67%)
1.4 Power Generation
Be it the generating capacity or plant performance or operational efficiency, NTPC’s Installed Capacity and performance depicts the company’s outstanding performance across a number of parameters.
NO. OF PLANTS CAPACITY (MW)
NTPC Owned
Coal 15 24,885
Gas/Liquid Fuel 7 3,955
Total 22 28,840
Owned By JVs
Coal & Gas 5 2,864
Total 27 31,704
Regional Spread of Generating Facilities
REGION COAL GAS TOTAL
Northern 7,525 2,312 9,837 Western 6,360 1,293 7,653 Southern 3,600 350 3,950 Eastern 7,400 - 7,400 JVs 924 1,940 2,864 Total 25,809 5,895 31,704
1.4.2 Coal Based Power Stations
With 15 coal based power stations, NTPC is the largest thermal power generating company in the country. The company has a coal based installed capacity of 24,885 MW.
COAL BASED
(Owned by NTPC) STATE COMMISSIONED CAPACITY(MW)
1. Singrauli Uttar Pradesh 2,000
2. Korba Chhattisgarh 2,100
3. Ramagundam Andhra Pradesh 2,600
4. Farakka West Bengal 1,600
5. Vindhyachal Madhya Pradesh 3,260
6. Rihand Uttar Pradesh 2,000
8. NCTPP, Dadri Uttar Pradesh 1,330
9. Talcher Kaniha Orissa 3,000
10. Feroze Gandhi, Unchahar Uttar Pradesh 1,050
11. Talcher Thermal Orissa 460
12. Simhadri Andhra Pradesh 1,000
13. Tanda Uttar Pradesh 440
14. Badarpur Delhi 705
15. Sipat-II Chhattisgarh 1,000
Total 24,885
Coal Based Joint Ventures:
COAL BASED (Owned by
JVs) STATE COMMISSIONED CAPACITY
1. Durgapur West Bengal 120
2. Rourkela Orissa 120
3. Bhilai Chhattisgarh 574
4. Kanti Bihar 110
Total 924
1.4.3 Gas/Liquid Fuel Based Power Stations
The details of NTPC gas based power stations is as follows GAS BASED (Owned by NTPC) STATE COMMISSIONED CAPACITY(MW) 1. Anta Rajasthan 413
2. Auraiya Uttar Pradesh 652
3. Kawas Gujarat 645
4. Dadri Uttar Pradesh 817
5. Jhanor-Gandhar Gujarat 648
6. Rajiv Gandhi CCPP
Kayamkulam Kerala 350
7. Faridabad Haryana 430
Gas Based Joint Ventures:
COAL BASED (Owned
by JVs) STATE COMMISSIONED CAPACITY
1. RGPPL Maharashtra 1940
Total 1940
1.4.4 Hydro Based Power Projects (Under Implementation)
NTPC has increased thrust on hydro development for a balanced portfolio for long term sustainability. The first step in this direction was taken by initiating investment in Koldam Hydro Electric Power Project located on Satluj river in Bilaspur district of Himachal Pradesh. Two other hydro projects under construction are Tapovan Vishnugad and Loharinag Pala. On all these projects construction activities are in full swing.
HYDRO BASED STATE APPROVED
CAPACITY(MW)
1. Koldam (HEPP) Himachal Pradesh 800
2. Loharinag Pala (HEPP) Uttarakhand 600
3. Tapovan Vishnugad (HEPP) Uttarakhand 520
Total 1,920
1.4.5 Renewable & Distributed Generation
Renewable Energy
Renewable energy (RE) is being perceived as an alternative source of energy for “Energy Security” and subsequently “Energy Independence” by 2020. Renewable energy technologies provide not only electricity but offer an environmentally clean and low noise source of power.
Objectives
NTPC plans to broad base generation mix by evaluating conventional and non-conventional sources of energy to ensure long run competitiveness and mitigate fuel risks.
Portfolio of Renewable Power
NTPC has also formulated its' business plan of capacity addition of about 1,000 MW through renewable resources.
Sl. No. RENEWABLE ENERGY SOURCES CAPACITY
1. Wind energy Farms 650 MW
2. Small Hydro Project 300 MW
3. Solar PV Power Project 5 MW
4. Solar Thermal 10 MW
5. Biomass Power Project 15 MW
6. Geothermal Power Project 30 MW
Total 1,010 MW
1.4.6 Distributed Generation
India’s ambitious growth plans require inclusion of all sectors, especially the rural sector where two third of our population lives. Such economic development cannot be achieved without availability of energy and subsequently efficient energy management which is crucial for rural development. As per census 2001, about 44% of the rural households do not have access to electricity. Some of the villages are located in remote & inaccessible areas where it would be either impossible or extremely expensive to extend the power transmission network.
Objective
· Implementation of distributed generation projects using locally available
renewable resources such as biomass, wind, solar, micro hydel, bio-fuel etc.
· Training & capacity building of local community to enable them to
independently manage, operate & maintain the plant • To ensure viability and long term sustainability of DG projects
· Integrated growth & development of rural areas by enhancing employment
education, income generation & livelihood opportunities
· To ensure implementation of various technologies as demo/pilot project
1.5 NTPC Operations
In terms of operations, NTPC has always been considerably above the national average. The availability factor for coal based power stations has increased from 89.32% in 1998-99 to 91.76% in 2009-10, which compares favourably with international standards. The PLF has increased from 76.6% in 1998-99 to 90.81% during the year 2009-10.
The table below shows that while the installed capacity has increased by 62.15% in the last twelve years the generation has increased by 99.84%.
Description Unit 1998-99 2009-10 % of Increase
Installed Capacity MW 17,786 28,840 62.15
Generation MUs 1,09,505 2,18,840 99.84
* Excluding JVs and Subsidiaries
The table below shows the detailed operational performance of coal based stations over the years.
OPERATIONAL PERFORMANCE OF COAL BASED NTPC STATIONS
Year Generation(BU) PLF(%) Availability Factor(%)
2009-10 218.84 90.81 91.76 2008-09 206.94 91.14 92.47 2007-08 200.86 92.24 92.12 2006-07 188.67 89.43 90.09 2005-06 170.88 87.52 89.91 2004-05 159.11 87.51 91.20 2003-04 149.16 84.40 88.79 2002-03 140.86 83.57 88.70 2001-02 133.20 81.11 89.09 2000-01 130.10 81.80 88.54 1999-00 118.70 80.39 90.06 1998-99 109.50 76.60 89.36
1.6 Turnaround Capability
NTPC has played an extremely important role in turning around sub-optimally performing stations. The phenomenal improvement in the performance of Badarpur, Unchahar, Talcher and Tanda by NTPC make them our big success stories.
Badarpur (705 MW)
The expertise in R&M and performance turnaround was developed and built up by NTPC with the operational turnaround of Badarpur TPS through scientifically engineered R&M initiatives. The PLF of the power station improved from 31.94% at the time of the takeover to 86.46% for the year 2007-08.
Unchahar (420 MW)
The Feroze Gandhi Unchahar Power Station was taken over by NTPC whereby the cash strapped UPSEB was rescued by the turnaround expertise of NTPC.
The remarkable speed and extent of the turnaround achieved can be seen in the table.
Talcher (460 MW)
An even more challenging turnaround story was being scripted at the OSEB's old power plant at Talcher. Taken over in June 1995, the table indicates the dramatic gains in the performance of the power plant as a result of NTPC’s expertise.
Tanda (440 MW)
Tanda Thermal Power Station was taken over by NTPC on the 15 January 2000.The PLF of the power station improved from 21.59% at the time of the takeover to 91.66% for the year 2007-08.
While NTPC bettered PPA commitments, from the viewpoint of capital requirements, turning around such old units is a low cost, high and quick return option. This unprecedented success helped the concerned SEBs and the entire nation in terms of economy and power availability.
1.7 NTPC Strategies
1.8 NTPC International Cell
Towards the end of last century, many countries started structural changes in their infrastructure sectors. Many countries decided to un-bundle their hitherto government controlled power sector. Further, in order to meet the growing demand for power, privatization of power projects emerged as the most outstanding choice. These actions of many progressive governments resulted in a number of opportunities for private players in power sector. These include development of power projects as Independent Power Producers (IPP).
Keeping its proactive tradition, NTPC launched a separate International Cell to meet the varied needs of IPPs and other International clients who are looking for a world
class service in power sector. The International Cell is fully backed by NTPC’s three decades of experience and expertise. The Cell is especially tuned to meet the requirements of International clients in terms of quick response, flexible service options and to deliver value for money.
1.8.1 Rich International Experience
NTPC has a rich experience of executing power sector related projects abroad. Some of the projects are:
· Turnkey supply and installation of 400 kV & 132 kV Transmission lines for
Dubai Electricity & Water Authority, Dubai
· Turnkey supply and installation of 132 kV Sub-stations for Dubai Electricity &
· Turnkey execution of 21 sub-stations for Asian Development Bank assisted 7th
Power Project for Nepal Electricity Authority, Nepal.
· Feasibility Studies for Mchuchuma Mining-cum-Power Project of about 400
MW for National Development Corporation, Tanzania.
· Preparation of Procurement plan for IDA funded National HIV / AIDS
Prevention Project of Ministry of Health, Nutrition & Welfare, Govt. of Sri Lanka.
· Executive training to ALBA Engineers for ALBA Bahrain
· Training to Technical personnel of Oman Refinery Company for Petroleum
India International (PII).
· Deputation of experts to Nigeria to act as shift charge engineers for gas fired
project AFAM at Nigeria from Steag encotec, India.
· Status assessment of Kipevu Power Station of KenGen. Kenya.
· Energy audit of power plants of Saudi Electricity Company in Kingdom of Saudi
Arabia from YBAK of Saudi Arabia.
· Deputation of Metallurgical expert to Mangalore and USA for technical
discussion with M/s General Electric in connection with failure of one of the Barge mounted Gas turbine belonging to GMR Energy Ltd. in India.
· Deputation of expert for assistance in due diligence of 683 MW Sidi Krier
Power project Egypt.
· Review of design engineering of 4 Nos. 132/33kV substations in Dubai for
DEWA, Dubai Investment Park & Tajera town.
· Experts’ services for supervision of commissioning and materials management
at 800MW Az Zour Gas Power Plant in Kuwait.
· Review of protocol document and performance data sheet at home office and
attending meeting at Kuwait and review of PG test calculation for 252 MW open cycle gas plant at Shuwaikh, Kuwait.
· Analysis of root cause for internal corrosion in HRSG tubes in Fujairah
Independent water and power project, UAE.
Pursuing Business Opportunities In:
Bahrain Bangladesh China Egypt
Indonesia Iran Jordan Kazakhstan
Malaysia Nigeria Saudi Arabia Sri Lanka
1.9 Ecological Monitoring Programme
NTPC has undertaken a comprehensive Ecological Monitoring Programme through Satellite Imagery Studies covering an area of about 25 Kms radius around some of its major plants. The studies have been conducted through National Remote Sensing Agency (NRSA), Hyderabad at its power stations at Ramagundam, Farakka, Korba, Vindhyachal, Rihand and Singrauli. These studies have revealed significant environmental gains in the vicinity areas of the project as a result of pursuing sound environment management practices. Some of these important gains which have been noticed are increase in dense forest area, increase in agriculture area, increase in average rainfall, decrease in waste land etc. In general, the studies, as such, have revealed that there is no significant adverse impact on the ecology due to the project activities in any of these stations. Such studies conducted from time to time around a power project have established comprehensive environment status at various post operational stages of the project.
2.1 Overview
The natural gas-fired combined cycle gas turbine (CCGT) based power plant and associated transmission and transformer facilities (T&T facilities) is located in an area of 324.58 acres in the village of Mujhedi, Neemka, Faridabad district, Haryana State, in India’s Northern region, targeting the elimination of supply deficits and contributions to living standard improvements and industrial development within the region.
*A indicates location of the plant
A yen loan of 56,154 million was extended from OECF (Overseas Economic Cooperation Fund) Japan to the President of India / National Thermal Power Corporation Ltd. (NTPC) and Powergrid Corporation of India Ltd. (POWERGRID) to cover the power plant and T&T facilities costs, excluding the land acquisition costs, project management costs, taxes and part of the costs for the switchyards, however, the portion necessary for the works to be undertaken by the end of FY95 (23,536 million yen) was in fact provided.
Outline of Loan Agreement
Loan Amount 23,536 million yen
Loan Disbursed Amount 19,937 million yen
Exchange of Notes December 1993
Loan Agreement January 1994
Terms and Conditions
-Interest Rate 2.6%
-Repayment Period (Grace
Period) 30 years (10 years)
-Procurement General untied
Final Disbursement Date March
Initially the entire Northern region was established as the project’s beneficiary area, and plant output was projected to be around 800MW so as to be capable of supplying an adequate volume of power. However, an 800MW output scale was found to be excessive in terms of securing fuel. In addition, with the exception of Haryana State, all other states in the region expressed reservations about future purchases of power from the plant, citing high fuel costs, thus a proposal was made to the Haryana State government regarding the conclusion of a power purchase contract, on condition that the entire volume of power produced at the Faridabad Power Station be supplied to the state. This proposal was accepted by NTPC and approved by the central government, in consequence of which the project’s beneficiary area was narrowed down from the entire Northern region to Haryana State alone.
The “Flare Gas Reduction Project” and "HBJ (Hazira-Bijaipur-Jagdishphur) Gas Pipeline Reinforcement Project” that were instituted as external requirements (the drilling for and supply of natural gas) for the establishment of this plant were respectively completed in 1999 and 1998. Both projects were jointly funded by JBIC and the World Bank as well as the Asian Development Bank (ADB), and their completion was also a precondition of gas supplies to the Faridabad Power Station. The projects were divided into a number of components; these dates indicate completion of the final components.
Power Plant Output
Due to the comparatively favorable nature of the terms for generation facilities stipulated by the winning contractor, plant output was fixed at 430MW*6. Switchyard facilities were also changed from the initial 400kV to 220kV compatibility since with the reduction in plant scale (800MW→400MW) and hence the plant was connected to 220kV power lines.
Transmission & Transformer Facilities
Since the plant turned out to be connected to the 220kV system, the construction / expansion of 400kV substations and the construction of incoming 400kV transmission lines were omitted, and two 220kV transmission line routes were constructed from the plant to existing substations.
Implementation Schedule (1) Power Plant
The power plant was completed in July 2000, two years and seven months behind the initially planned date (December 1997). This delay was caused by approval procedures accompanying the changes to output scale and so on, however, as Table 3 illustrates, construction of the plant per se progressed extremely smoothly.
Construction Schedule for Key Power Plant Components
Component Initial schedule Actual
No. 1 Gas turbine generator 30 months 23 months No. 2 Gas turbine generator 32 months 27 months
(2) Transmission & Transforming Facilities
For the same reason as cited above, construction started three years behind schedule, but was completed in 16 months, which was essentially as per the plans (14 months). The delays occurring prior to construction are believed to have been the product of limitations in NTPC’s ability to deal, unassisted, with the numerous state governments and related organizations involved in the process. However, given the fact that debate over the changes in output scale linked to hold ups in the approval process, it might have been possible to confirm / verify the prospects for power purchase by each of the states in advance, thereby reducing the duration of the delays. However, it would be beneficial to evaluate how the construction work was completed in less time than initially projected under such circumstances.
Contribution of the plant in Haryana State
The Faridabad Power Station commenced on-grid generation in 1999 and all power produced (100%) at the plant is being supplied to Haryana State. Assuming that the plant had not existed in FY99, the supply deficit in the state would have deteriorated from 2.3% to 9.0%*11. Moreover, in a trial calculation for the following year, FY00, the supply deficit would worsen from 2.8% to 15.8%. In fact, the peak supply deficit dropped from 8.3% in FY98 to 3.3% in FY00, a circumstance to which the Faridabad Power Station is believed to making a certain contribution*12. The net electric energy production had reached approximately 2,797MWh in FY01. This is roughly equivalent to 16% of total power consumption in Haryana State (17,856MWh). Further, peak demand (FY01) was 3,004MW with the plant supplying 12.7% of the demand during peak times. In summary, the plant has attained the initially set targets.
Environmental Impacts
NTPC periodically measures effluent and atmospheric concentrations of environmental pollutants including nitrogen oxide (NOx) and sulfur oxide (SOx), as
well as the quality of effluent and water in the river into which said effluent is discharged (suspended particulate matter, heated effluent, etc.). All results to date have been in conformity with the standards governing emissions and the environment established by the national government, and there have been no specific reports of adverse environmental impacts.
Power produced at the Faridabad Power Station is purchased by Haryana Vidyut Prasaran Nigam Ltd., (HVPNL), the distribution company that came into being as the result of the unbundling of Haryana State Electricity Board (HSEB).
Item Plan Actual
1) Project Scope Power station Transmission / transformer facilities
1) Gas turbine generators, 140MW × 2
2) Steam turbine generators, 130MW × 1
3) Heat recovery steam gas boiler × 2
4) Monitoring /control equipment, water treatment facilities, etc.
5) Switchyard and related facilities
1) 400kV Dadri-Ballabgarh transmission line
2) 400kV Ballabgarh-Jaipur transmission line
3) Construction and expansion of substation facilities
1) Gas turbine generators, 137MW × 2
2) Steam turbine generators, 156 MW × 1 3) As planned 4) As planned 5) Changed from 400kV to 220kV 1) 220kV Faridabad-Samaypur transmission line 2) 220kV Faridabad-Palla transmission line
3) Only 220kV bay constructed
2) Implementation schedule Power plant Transmission lines Substations Dec. 1994 - Dec. 1997 Aug. 1995 - Sep. 1996 Aug. 1994 - Sep. 1996 Jan. 1998 - Jul. 2000 Aug. 1998 - Dec. 1999 Aug. 1998 - Dec. 1999
2.2 Combined Cycle Gas Turbine (CCGT) plant
A combined cycle is characteristic of a power producing engine or plant that employs more than one thermodynamic cycle. Heat engines are only able to use a portion of the energy their fuel generates (usually less than 50%). The remaining heat (e.g., hot exhaust fumes) from combustion is generally wasted. Combining two or more thermodynamic cycles, such as the Brayton cycle and Rankine cycle, results in improved overall efficiency.
In a combined cycle power plant (CCPP), or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat is used to make steam to generate additional electricity via a steam turbine; this last step enhances the efficiency of electricity generation.
Design Principle
In a thermal power station water is the working medium. High pressure steam requires strong, bulky components. High temperatures require expensive alloys made from nickel or cobalt, rather than inexpensive steel. These alloys limit practical steam temperatures to 655 °C while the lower temperature of a steam plant is fixed by the boiling point of water. With these limits, a steam plant has a fixed upper efficiency of 35 to 42%.
An open circuit gas turbine cycle has a compressor, a combustor and a turbine. For gas turbines the amount of metal that must withstand the high temperatures and pressures is small, and lower quantities of expensive materials can be used. In this type of cycle, the input temperature to the turbine (the firing temperature), is relatively high (900 to 1,400 °C). The output temperature of the flue gas is also high (450 to 650 °C). This is therefore high enough to provide heat for a second cycle which uses steam as the working fluid; (a Rankine cycle).
In a combined cycle power plant, the heat of the gas turbine's exhaust is used to generate steam by passing it through a heat recovery steam generator (HRSG) with a live steam temperature between 420 and 580 °C. The condenser of the Rankine cycle is usually cooled by water from a lake, river, sea or cooling towers. This temperature can be as low as 15 °C.
Typical size of CCGT plants
For large scale power generation a typical set would be a 400 MW gas turbine coupled to a 200 MW steam turbine giving 600 MW. A typical power station might comprise of between 2 and 6 such sets.
Efficiency of CCGT plants
By combining both gas and steam cycles, high input temperatures and low output temperatures can be achieved. The efficiency of the cycles add, because they are powered by the same fuel source. So, a combined cycle plant has a thermodynamic cycle that operates between the gas-turbine's high firing temperature and the waste heat temperature from the condensers of the steam cycle. This large range means that the Carnot efficiency of the cycle is high. The actual efficiency, while lower than this, is still higher than that of either plant on its own.
Supplementary firing and blade cooling
The HRSG can be designed with supplementary firing of fuel after the gas turbine in order to increase the quantity or temperature of the steam generated. Without
supplementary firing, the efficiency of the combined cycle power plant is higher, but supplementary firing lets the plant respond to fluctuations of electrical load. Supplementary burners are also called duct burners.
More fuel is sometimes added to the turbine's exhaust. This is possible because the turbine exhaust gas (flue gas) still contains some oxygen. Temperature limits at the gas turbine inlet force the turbine to use excess air, above the optimal stoichiometric ratio to burn the fuel. Often in gas turbine designs part of the compressed air flow bypasses the burner and is used to cool the turbine blades.
Fuel for combined cycle power plants
Combined cycle plants are usually powered by natural gas, although fuel oil, synthesis gas or other fuels can be used. The supplementary fuel may be natural gas, fuel oil, or coal. Bio-fuels can also be used. Integrated solar combined cycle power stations combine the energy harvested from solar radiation with another fuel to cut fuel costs and environmental impact.
Configuration of CCGT plants
The combined-cycle system includes single-shaft and multi-shaft configurations. The single-shaft system consists of one gas turbine, one steam turbine, one generator and one Heat Recovery Steam Generator (HRSG), with the gas turbine and steam turbine coupled to the single generator in a tandem arrangement on a single shaft. Key advantages of the single-shaft arrangement are operating simplicity, smaller footprint, and lower startup cost. Single-shaft arrangements, however, will tend to have less flexibility and equivalent reliability than multi-shaft blocks. Additional operational flexibility is provided with a steam turbine which can be disconnected, using an SSS Clutch, for start up or for simple cycle operation of the gas turbine.
Multi-shaft systems have one or more gas turbine-generators and HRSGs that supply steam through a common header to a separate single steam turbine-generator. In terms of overall investment a multi-shaft system is about 5% higher in costs.
Single- and multiple-pressure non-reheat steam cycles are applied to combined-cycle systems equipped with gas turbines having rating point exhaust gas temperatures of approximately 540 °C or less. Selection of a single- or multiple-pressure steam cycle for a specific application is determined by economic evaluation which considers plant installed cost, fuel cost and quality, plant duty cycle, and operating and maintenance cost.
Multiple-pressure reheat steam cycles are applied to combined-cycle systems with gas turbines having rating point exhaust gas temperatures of approximately 600 °C.
The most efficient power generation cycles are those with unfired HRSGs with modular pre-engineered components. These unfired steam cycles are also the lowest in cost. Supplementary-fired combined-cycle systems are provided for specific application.
The primary regions of interest for cogeneration combined-cycle systems are those with unfired and supplementary fired steam cycles. These systems provide a wide range of thermal energy to electric power ratio and represent the range of thermal
energy capability and power generation covered by the product line for thermal energy and power systems.
2.2
Water treatment
Raw water for steam turbine generation (STG), use as circulating water (CW) and other purposes is taken from the Agra canal through an extensive piping system. The water is contaminated with various minerals and other impurities which readily dissolve in it. They have to be removed from the raw water before it can be used for any industrial applications. For this purpose water is treated first by a Pre-Treatment (PT) plant and then by a De-Mineralization (DM) plant.
2.2.1 Pre-treatment (PT) plant
Pre-treatment plant consists mainly of clarifiers, chemical house, gravity filter, pressure filter and Chlorine dozing. A Cooling Water (CW) clarifier caters water requirement of CW makeup, HVAC makeup, fire fighting and auxiliary water requirements. For back washing gravity filters, blowers have been provided. Sand in the form of quartz, free from clay, fine particles and soft grains is used in the gravity filters with sizes ranging between 0.45 to 0.70 mm.
The nature and concentration of impurities and objectionable constituents of water determine the methods to be employed for the treatment of water. Different techniques are used for removal of mechanical impurities, Clayey turbidities, Colloidal, dissolved impurities, organic matter, detergents, polycyclic aromatics,
colouring substances, oils and aliphatic hydrocarbons etc. which impart taste or odour, polyvalent heavy-metal compounds, germs and bacteria.
The water is given an initial dose of chlorine when it is in the raw water tank. This water is pumped by three CW pumps for use as circulating water while other three pump this water for further processing as described below:
1. The pumped water is passed to an Aerator, which oxidizes soluble iron in the Raw Water (RW) from Ferrous to Ferric State.
2. Water flows to the Stilling Chamber to break the turbulence.
3. Water is then taken into the Flash Mixer for intimate mixing of chemicals with the raw water.
4. The raw water is dosed with Alum or PAC (Poly Aluminium Chloride), Lime and Polyelectrolyte to coagulate and flocculate the suspended / colloidal matter and form floc of higher nuclei thereby enhancing the efficiency of sedimentation.
5. Chemically dosed raw water is then fed into the clariflocculator unit wherein flocculation and clarification of raw water takes place.
6. The sludge generated in the clariflocculator is bled via Telescopic Bleeds to an underground Sludge Pit. The sludge collected from the plant is finally pumped out.
7. Clarified water is collected in the launder of the clarifier located on the top periphery from where it flows to the clarified water reservoir.
The clearified water is then pumped to the De-Mineralisation (DM) plant for removing inorganic impurities and making the water suitable for use in Heat Recovery Steam Generator (HRSG) and Steam Turbine (ST).
2.2.2 De-Mineralisation (DM) plant
Demineralisation is the process of removing the mineral salts from water by ion-exchange. Impurities that remains dissolved in water dissociate to form positive and negative charged particles known as ions. These impurities or compounds are called electrolytes. Generally, all natural water has electrolytes in varying concentrations. An ion-exchange vessel holds ion-exchange resin of the required type through which water is allowed to pass. The selective ions in the water are exchanged with ions or radicals loosely held by the resin. In this way, the water is passed through several vessels or a mixed bed vessel so that both positive and negative ions are removed and water is demineralised. The DM plant at Faridabad gas power plant (FGPP) was provided by Ion Exchange (I) Ltd (Mumbai), over a period of 20 months on 30-03-2000.
The demineralization plant is a two stream plant having a normal treatment capacity of 100 m3/hr. Each demineralising chain comprises of following units:
a) ACF : Activated Carbon Filter b) WAC :Weak Acid Cation Exchanger c) SAC :Strong Acid Cation Exchanger
d) DG & DGWT :Degasser Tower and Degassed Water Storage Tank e) WBA :Weak Base Anion Exchanger
f) SBA : Strong Base Anion Exchanger g) MB :Mixed Bed Exchanger
Apart from the above a hot water tank is provided for heating “power water” required for regeneration of SBA/WBA unit & when residual silica at outlet is high.
Each exchanger is mounted with several instruments for local and/or panel indication, control or alarm to monitor the various parameters for smooth running of the plant. Each exchanger is mounted with flow instrument (Rotameter) at the service inlet, pressure gauge at inlet and outlet, and resin trap at the outlet.
The plant has predominantly DOPC diaphragm valves mounted on the service inlet, backwash inlet and outlet, bleed and air release, Service outlet and regenerant valves are DOPO diaphragm valves. The block valves open and close with the regenerant inlet valve while the bleed valves open and close when the block valves and regenerant inlet valves open and close respectively. Needle valves are used for transmitter, pH sample, pressure indicator isolation, drain and sample while ball valves are used for flow indicator and flow switch isolation, inter connecting valves between service outlet header of two streams of two streams are manually operated butterfly valves.
Carbon filters are provided upstream for residual chlorine reduction and organic removal in the water supply to the demineraliser. Downflow service and upflow
regeneration is employed for the primary Cation and Anion exchangers. The mixed bed is designed with simultaneous regeneration of cation and anion resin. For anion resin, the caustic dilution system is designed with on-line hot caustic regeneration.
The WAC and SAC remove the cationic inorganic impurities while the WBA and SBA remove the acidic inorganic impurities present in water.
2.4 Components
2.4.1 Air filters
Ambient air can be contaminated by solids, liquids, or gases. Of these three, contamination by solids is the most common, and usually the most serious situation. When account is taken of ’the large flow rates of gas turbines, it is evident that the total quantity of dust which is ingested can be appreciable when summed over hundreds or thousands of fired hours. Therefore, Inlet air filtration systems are essential on any gas turbine. Some of the consequences of poor inlet filtration are fouling, erosion, and corrosion.
Feed Water
ACF WAC SAC
Degasser
Five basic filtration mechanisms are described below:
The first filtration mechanism is inertial impaction. This type of filtration is applicable to particles larger than 1 micron in diameter. The inertia of the large heavy particles in the flow stream causes the particles to continue on a straight path as the flow stream moves to go around a filter fiber. The particulate then impacts and is attached to the filter media and held in place as shown in the top picture of figure .This type of filtration mechanism is effective in high velocity filtration systems.
The next filtration mechanism, diffusion, is effective for very small particles typically less than 0.5 microns in size with low flow rates. These particles are not held by the viscous forces in the fluid and will diffuse within the flow stream along a random path (second picture). The path the particle takes depends on its interaction with nearby particles and gas molecules. As these particles diffuse in the flow stream, they collide with the fiber and are captured. The smaller a particle and the lower the flow rate through the filter media, the higher probability that the particle will be captured. The next two filtration mechanisms are the most well known; interception and sieving. Interception occurs with medium sized particles that are not large enough to leave the flow path due to inertia or not small enough to diffuse. The particles will follow the flow stream where they will touch a fiber in the filter media and be trapped and held. Sieving is the situation where the space between the filter fibers is smaller than the particle itself, which causes the particle to be captured and contained.
Another type of filtration mechanism which is not shown in Figure is viscous impingement. This type of mechanism uses the inertial impaction mechanism to capture particles. What makes this mechanism unique is that the filter is covered with a thin layer of oil which causes the captured particles to adhere to the filter surface, thus preventing them from being released downstream. The amount of particles captured is maximized by creating a torturous path for the air. This results in a filter
with many changes in flow direction. This filtration mechanism is effect for medium to large size particles.
The last filtration mechanism is electrostatic charge. This type of filtration is effective for particles in the 0.01 to 10 micron size range. The filter works through the attraction of particles to a charged filter. In gas turbine applications, this charge is applied to the filter before installation during the manufacturing process. Filters always lose their electrostatic charge over time because the particles captured on their surface occupy charged sites, therefore neutralizing their electrostatic charge. As the charge is lost, the filter efficiency for small particles will decrease. However, it should be noted that as the filter is loaded, the filtration efficiency increases. This will offset some of the loss of filtration efficiency due to the lost charge. Figure below shows a comparison of a filter’s total efficiency based on the various filtration mechanisms that are applied.
2.4.2 Compressor-Gas Turbine- Generator
A gas turbine is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbine's blades, spinning the turbine which powers the compressor and drives the generator.
Before starting the turbine, compressor has to be started. For this purpose, an electric motor is mounted on the same shaft as that of the turbine. The motor is energised externally. Upon reaching 20% of the rated rpm the gas turbine is ignited. It is speeded up higher and takes the system to approximately 50% or its rated rpm. From this point on, any further increase in speed is accomplished by the gas turbine and the motor is disconnected. Once the unit starts, a part of the mechanical power of the turbine drives the compressor and there is no need of the motor.
Faridabad plant is equipped with two gas turbines provided by Siemens (V94.2 model 3) with a capacity of 137.6 MW. Each turbine consists of a 16 stage compressor and a four stage turbine mounted on a single shaft with four bearings as shown in figure.
Generator Compressor Turbine
Journal Bearing
2.4.3 Diverter-Damper
Since the gas turbine has two options; one is to run in open cycle i.e. by passing HRSG or waste heat recovery boiler (WHRB) and second (normal) mode in which HRSG is in circuit, hence a damper has been provided on the path of flue gas. This damper will close the path either towards HRSG or towards the by-pass stack.
.
Movement of the damper is 900 and it is basically rectangular shaped plate which seats
perfectle on its seal provided at the two places. Blade of diverter damper is made off carbon steel supported on suitable modification on both sides to resist temp of 5400C and sudden cooling and heating during operation.
2.4.4 Heat Recovery Steam Generator (HRSG)
Faridabad gas power project, popularly known as FGPP, is equipped with two HRSGs of 277 t/hr each. A heat recovery steam generator or HRSG is an energy recovery heat exchanger that recovers heat from a hot gas stream. It produces steam that can be
used in a process or used to drive a steam turbine. HRSGs consist of three major components. They are the Evaporator, Superheater, and Economizer. The different components are put together to meet the operating requirements of the unit. In horizontal type HRSGs, exhaust gas flows horizontally over vertical tubes as shown in figure.
Direct Benefits:
Recovery of waste heat has a direct effect on the efficiency of the process. This is reflected by reduction in the utility consumption & costs, and process cost. Indirect Benefits:
a) Reduction in pollution: A number of toxic combustible wastes such as carbon
monoxide gas, sour gas, carbon black off gases, oil sludge, Acrylonitrile and other plastic chemicals etc, releasing to atmosphere if/when burnt in the incinerators serves dual purpose i.e. recovers heat and reduces the environmental pollution levels.
b) Reduction in equipment sizes: Waste heat recovery reduces the fuel consumption,
which leads to reduction in the flue gas produced. This results in reduction in equipment sizes of all flue gas handling equipments such as fans, stacks, ducts, burners, etc.
c) Reduction in auxiliary energy consumption: Reduction in equipment sizes gives
additional benefits in the form of reduction in auxiliary energy consumption like electricity for fans, pumps etc.
Flue gas from the combustion turbine enters the HRSG at a temperature of around 5400C and is reduced in temperature by the superheater, reheater, dram evaporative surfaces, and economizer before it enters the stack. Condensate from the combined cycle condenser enters the deaerator, and flows through the economizer to the drum. Steam from the drum flows to the superheater and then to the high pressure turbine. Steam from the high pressure steam turbine flows through the reheater and then to the intermediate pressure turbine.
Pinch points and approach temperatures are important HRSG design parameters. Reducing these temperatures will increase cycle efficiency.
2.4.5 Steam Turbine-Generator
The Faridabad gas power plant is equipped with BHEL 156 MW steam turbine. The heat energy in the steam from HRSG is converted to mechanical energy in the steam turbine. The turbine uses the mechanical energy from the steam to turn the generator which then converts the mechanical energy to electrical energy.
The steam expands and cools in the energy conversion in the steam turbine. A small fraction of the steam condenses in the steam turbine and appears as small water droplets. The mixture of steam and water exhausts from the steam turbine to the condenser where the remaining steam is condensed into water, usually referred to as condensate. The heat required to change the state between steam and water, called the heat of vaporization, is rejected to the circulating water through heat transfer in the condenser. The condensate is then pumped back to the HRSG through heat exchangers designed to capture more heat through heat transfer. The process is then repeated.
Bearing and Lubication:
Two types of bearings are used to support and locate the rotors of steam turbines: Journal bearings are used to support the weight of the turbine rotors. A journal bearing consists of two half-cylinders that enclose the shaft and are internally lined with Babbitt, a metal alloy usually consisting of tin, copper and antimony; and Thrust bearings axially locate the turbine rotors. A thrust bearing is made up of a series of Babbitt lined pads that run against a locating disk attached to the turbine rotor.
High-pressure oil is injected into the bearings to provide lubrication. The oil is carefully filtered to remove solid particles. Specially designed centrifuges remove any water from the oil. Shaft Seals The shaft seal on a turbine rotor consist of a series of ridges and groves around the rotor and its housing which present a long, tortuous path for any steam leaking through the seal. The seal therefore does not prevent the steam from leaking, merely reduces the leakage to a minimum. The leaking steam is collected and returned to a low-pressure part of the steam circuit.
Turning gear:
Large steam turbines are equipped with "turning gear" to slowly rotate the turbines after they have been shut down and while they are cooling. This evens out the temperature distribution around the turbines and prevents bowing of the rotors.
2.4.6 Main Control Room (MCR)
The control room is the heart of the processing system. It is the core of the plant and the main part of the supervision is carried out here. Working as an operator involves many hours in front of computer screens. A pleasant and appropriate surrounding enhances the work spirit and stamina.
An interface provides the operator with the general following information:
· After initiating an action within a system the operator is clearly informed of the
result of their action.
· If there is a delay in the system that prevents the operator from being informed
of the result of his/her action, the system informs the operator of this fact.
· If an action is made in error then it is possible to reverse such an action where
it would not be detrimental to plant safety to do so.
· The system informs the operator of any deviations from safe operating levels,
through alarms.
For large plants, control rooms are likely to be situated in separate buildings away from the process plant which they serve. For medium or small plants control rooms may be within the plant building or control panels may be located local to the plant. 2.4.7 Cooling tower
Induced Draft Cooling Tower of 29000 m3/hr capacity has been built to cool the hot
water coming out of condenser of steam turbine. It is capable to reduce water temperature by 110.
The primary task of a cooling tower is to reject heat into the atmosphere. This heat rejection is accomplished through the natural process of evaporation that takes place when air and water are brought into direct contact in the cooling tower. The evaporation is most efficient when the maximum water surface area is exposed to the maximum flow of air, for the longest possible period of time.
Cooling towers are designed in two different configurations, counter flow and cross flow. The specific configuration indicates the direction of air flow through the tower relative to the direction of the water flow.
Induced draft cooling towers are constructed such that the incoming circulating water is dispersed throughout the cooling tower via a spray header. The spray is directed down over baffles that are designed to maximize the contact between water and air. The air is drawn through the baffled area by large circulating fans and causes the evaporation and the cooling of the water.
The heat exchanger media in the cooling tower is PVC fills packed in box form after gluing each other suitably at the top of the cooling tower. Placed just below the propeller fans drift eliminator, PVC fills (grey coloured) are cross corrugated with minimum sheet thickness of 0.2 mm and minimum sheet spacing is 17 mm.
Drift Eliminator:
It is placed between propeller fan and PVC fills boxes. The purpose of drift eliminator is to arrest carry over of minute water particles form air so that drift loss is a minimum of .05% of total water circulation. Drift eliminator is nothing but closely packed PVC sheet arrangements.
2.5 Switchyard
A Switchyard or Substation, consisting of large breakers and towers, is located in an area close to the plant. The substation is used as the distribution center where:
· electrical power is supplied to the plant from the outside, and · electrical power is sent from the plant
Often there are at least 2 main Buses. The generated power at FGPP is transmitted as 220 kV to the grid thorugh four output lines: 2 to Samaipur (ballabgarh) and 2 to palla( faridabad), where other substations step down the voltage for distribution to households.
The switchyard at FGPP was erected by Power Grid Corporation Of India Ltd. (NR) in 1998.
