THE FOUR MAIN TYPES OF NDT

THERE ARE FOUR MAIN TYPES OF NDT  METHODS USED IN POWER PLANTS

Ultrasonic testing

Ultrasonic testing uses high-frequency sound waves called ultrasonic pulse waves to detect flaws or other imperfections or defects in metal components, and it can also be used to identify and monitor changes like shifts in thickness within the components that may result in failure or other problems in the future. One of the most common uses of ultrasonic testing is to evaluate corrosion in pipelines and other enclosed structures or components. Ultrasonic testing is most commonly performed on metals and metallic alloys, but it can also be used to test concrete and composites, and sometimes even wood. Although the method offers the advantage of deep penetration to evaluate problems within components, ultrasonic testing requires a high degree of training and competence to apply the method and interpret the results. Results also may be affected by surface imperfections or irregularities.

Magnetic particle testing

Also called magnetic particle inspection (MPI), this technique can be used in metals that have magnetic properties (also called ferromagnetic materials) such as iron, cobalt, nickel and some alloys. MPI works by issuing a magnetic field into the component being tested – essentially magnetizing the component. Next, iron particles are applied to the surface either in a dry form or suspended in liquid. Because even the tiniest cracks and fissures will allow some of the magnetism to “leak” out, these particles become attracted to the tiny cracks, building up and providing evidence of a leak, or “indication.” The component may be magnetized by an electrical current, called direct magnetization, or indirectly by applying a magnetic field to the outside of the component. Like ultrasonic testing, this approach requires considerable training and expertise

Liquid penetrant testing

Liquid penetrant testing is one of the oldest methods of non-destructive testing. In this method, two solutions are used – a penetrant that is first applied to the surface of the component to be tested and a developer that combines with the penetrant to help reveal tiny cracks or other imperfections. After the penetrant is applied, it is allowed to “soak in” for a prescribed period of time to help reveal defects that extend below the component’s surface. Liquid penetrant testing is used in a wide variety of industries and is one of the most popular techniques of non-destructive testing because it is relatively inexpensive, requires no costly special equipment and relies on limited experience and training, making it widely accessible to companies of all sizes.

Radiographic testing

Radiographic testing uses x-rays or radioactive isotopes to evaluate components in much the same way a doctor uses an x-ray to evaluate the structures inside a human body. This type of testing works by sending the radiation through the component and measuring the amount that emerges on the opposite side. The result is a photographic-type image that reflects areas of different densities, including areas where material may be missing or thinned, such as in cracks or areas of weakness. Radiographic testing can be difficult to use on components with irregular surface areas since those irregularities can influence the thickness of the materials that are being evaluated.

INDIA'S MOST TOP TEN POWER PLANTS

More than 65% of India's electricity generation capacity comes from thermal power plants, with about 85% of the country's thermal power generation being coal-based. The 10 biggest thermal power stations operating in India are all coal-fired, with seven of them owned and operated by state-run National Thermal Power Corporation (NTPC). Power-technology.com profiles India's 10 biggest thermal power plants by installed capacity.

1 :- Vindhyachal Thermal Power Station, Madhya Pradesh

Vindhyachal Thermal Power Station in the Singrauli district of Madhya Pradesh, with an installed capacity of 4,760MW, is currently the biggest thermal power plant in India. It is a coal-based power plant owned and operated by NTPC.

Construction of the plant, which comprised 12 generating units (six 210MW units and six 500MW units), had begun in 1982. The first unit was commissioned in 1987, while the sixth 500MW was commissioned in April 2013. An additional 500MW unit was commissioned in August 2015, increasing the plant’s gross capacity from 4,260MW to 4,760MW.

The plant uses coal from the NCL-operated Nigahi mine and water from the discharge canal of Singrauli Super Thermal Power Station. The turbine manufacturers for the Vindhyachal Thermal Power Station include Russian companies LMZ, Electrosila and the Indian BHEL. The 500MW units were supplied by BHEL.

2 :- MUNDRA THERMAL POWER STATION , GUJARAT

TheW 4,620MW Mundra Thermal Power Station located in the Kutch district of Gujarat is currently the second biggest operating thermal power plant in India. It is a coal-fired power plant owned and operated by Adani Power.

The power plant consists of nine generating units (four 330MW units and five 660MW units). The first 330MW unit was commissioned in May 2009 and the last 660MW unit of the plant commissioned in March 2012. The coal used for the power plant is mainly imported from Indonesia. The plant’s water source is the sea water from the Gulf of Kutch.

The boilers and generators for the first four units were supplied by Babcock & Wilcox and Beijing Beizhong respectively. SEPCO III, China was the EPC contractor for the last five 660MW units, which feature super critical technology.

The boilers were supplied by Harbin Boiler and the turbine and generators were supplied by Dongfang Machinery.

3 :- MUNDRA ULTRA MEGA POWER PLANT , GUJARAT

The 4,000MW Mundra Ultra Mega Power Plant (UMPP), also located in the Kutch district of Gujarat, ranks as the third largest thermal power plant in India. It is a coal-fired power plant owned and operated by Coastal Gujarat Power Limited (CGPL), a subsidiary of Tata Power.

The thermal power plant consists of five generating units, each of 800MW capacity. Construction of the plant began in March 2009.

The first unit of the Mundra UMPP was commissioned in March 2012 and the last unit was commissioned in March 2009. The plant uses 12 billion tonnes of imported coal per annum.

The plant features super-critical boiler technology. Doosan Heavy Industries & Construction was the EPC contractor for this project. The five boilers for the plant were also supplied by Doosan. Toshiba supplied the steam turbine generators.

4 :-Talcher Super Thermal Power Station, Odisha

Talcher Super Thermal Power Station or NTPC Talcher Kaniha, located in the Angul district of Odisha, is a 3,000MW coal-fired power plant owned and operated by NTPC. The power station currently ranks as the fourth largest operational thermal power plant in India.

NTPC Talcher Kaniha plant consists of six 500MW units. The first unit of the plant was commissioned in February 1995 and the last unit began operations in February 2005. Turbine manufacturers for the plant were ABB and BHEL.

The coal used by Talcher Super Thermal Power plant is sourced from the Lingraj Block of Talcher Coal Field. The plant uses water Samal Barrage Reservoir on Brahmani River in Odisha.

5 :-Sipat Thermal Power Plant, Chhattisgarh

The 2980MW Sipat Super Thermal Power Plant located at Sipat in the Bilaspur district of Chhattisgarh, ranks as the fifth largest thermal power station in India. It is a coal-based power plant owned and operated by NTPC.

The power plant built in two stages is installed with six generating units (three 660MW super-crtical units and three 500MW units). The first unit of the plant commenced commercial operations in August 2008, while the last unit was commissioned in June 2012.

The power plant, built with an estimated cost of more than $2bn, was renamed as Rajiv Gandhi Super Thermal Power Station in September 2013. Coal for the Sipat plant is sourced from Dipika Mines of South Eastern Coalfields Limited (SECL). The plant uses water from the Right Bank Canal (RBC) originating from the Hasdeo Barrage.

6 :-NTPC Dadri, Uttar Pradesh

NTPC Dadri or National Capital Power Station (NCPS) owned and operated by NTPC is located in the Gautam Budh Nagar district of Uttar Pradesh, about 48km from the Indian capital New Delhi. The power station, with an installed capacity of 2637MW (1820MW- coal based and 817MW gas based), ranks as the sixth largest thermal plant in India.

The power station consists of six coal-fired units (four 210MW units and two 490MW units) and six gas-based generating units (four 130.19MW gas turbines and two 154.51MW steam turbines). The first coal-fired unit was commissioned in October 1991 and the last unit was commissioned in July 2010. The gas-based generating units were commissioned between 1992 and 1997.

The coal for NTPC Dadri is sourced from Piparwar Mines, Jharkhand. The gas is sourced from GAIL Hazira-Bijapur-Jagdishpur (HBJ) Pipeline. The water source for the thermal power station is the Upper Ganga Canal

7 :- NTPC Ramagundam, Andhra Pradesh

NTPC’s Ramagundam thermal power plant in the Karimnagar district of Andhra Pradesh ranks as the seventh largest thermal power plant in India and the largest in south India. The coal-fired power plant has an installed capacity of 2600MW.

The power plant built in three phases consists of seven generating units (three 200MW units and four 500MW units. The first unit of the plant started operations in November 1983 and the last 500MW unit was commissioned in August 2004. The boilers and turbines of the plant were supplied by BHEL.

The power plant uses coal from South Godavari Coal Fields of Singrani Collieries and Korba Coal Fields of SECL. The sources of water for the plant are Sri Ram Sagar Dam on Godavari River and D-83 Canal from Pochampad Reservoir. The power generated at the plant is uniformly distributed among Andhra Pradesh, Tamil Nadu, Kerala, Karnataka and Maharashtra.

8 :- Korba Super Thermal Power Plant, Chattisgarh

Korba Super Thermal Power Plant located in the Korba district of Chhattisgarh, with 2600MW of installed capacity, also ranks as the seventh largest thermal power plant in India. It is a coal-fired power plant owned and operated by NTPC.

The power plant built in three phases comprises of seven generating units (three 200MW units and four 500MW units). The first unit of the Korba thermal power plant was commissioned in March 1983. The last 500MW unit at the plant was commissioned in December 2010.

The power plant uses coal from Kusmundha and Gevra mines in the Korba Coalfield. The water source of the plant is Hasdeo River, a tributary of Mahanadi River.

9 :-Rihand Thermal Power Station, Uttar Pradesh

Rihand Thermal Power Station at Rihandnagar in the Sonebhadra district of Uttar Pradesh ranks as the ninth largest thermal power plant in India. The coal-based power plant with an installed capacity of 2,500MW is owned and operated by NTPC.

Rihand Thermal Power Plant consists of five generating units of 500MW capacity each. The first unit was commissioned in March 1988. The fifth unit of the plant was commissioned in May 2012.

Coal for the Rihand Thermal Power Station is sourced from Amlori, Amloric expansion and the Dudhichua Mines in Madhya Pradesh. The plant uses water from the Rihand Reservoir built on 

10 :- Jharsuguda Thermal Power Plant, Odisha

Jharsuguda Thermal Power Plant, in the Jharsuguda district of Odisha, is currently the tenth largest thermal power plant operating in India. It is a 2400MW coal-fired power plant owned and operated by Sterlite Energy, a 100% subsidiary of Vedanta Resources.

The power plant is installed with four 600MW units. The first generating unit was commissioned in August 2010. The fourth unit was commissioned in March 2013. The coal used by the plant is sourced from the IB Valley coal field in the Jharsuguda district.

The Jharsuguda Thermal Power Plant was built with an estimated investment of $1.3bn. The SEPCO III Electric Power Construction Company of China was the EPC contractor for this thermal power project.

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