NTPC Limited’s 1,320 MW Khargone Super Thermal Power Station, located in Selda and Dalchi villages in Khargone district, Madhya Pradesh, is the first ultra supercritical thermal power plant in the country. The 660 MW Unit 1 of the project was commissioned on August 30, 2019, setting a new benchmark for the thermal power generation industry.
Set up on an engineering, procurement and construction (EPC) basis by Larsen & Toubro (L&T), this unit has an efficiency of about 41.5 per cent, the highest in the country. “This means it will consume less coal than other units, which will also result in CO2 emission reduction. Overall, due to the high efficiency, we will be benefitting in monetary terms as well as from the environment point of view,” says an NTPC spokesperson.
For the first unit, NTPC has completed 72 hours of continuous full load operation as of end-September, which is a key CERC requirement for declaring the commercialisation of any unit. The unit has been running continuously for the past 18 days without any issues, which proves that it is now ready for sustainable and reliable operation. Power Line takes a look at the features of the Khargone project and discusses the outlook for ultra supercritical technologies…
This ultra supercritical unit has steam temperature of 603 ºCelsius and pressure of 279 kg per cm2. It is designed with a twin fire vortex resulting in higher efficiencies, enabling the plant to consume less coal, hence lower emissions in comparison to sub-critical and supercritical power plants.
P92 (steel alloy for meeting the high temperature requirements of power plants) has also been used successfully for the first time for the superheater, reheater header and critical piping. It has a one-of-its-kind 400 kV gas insulated switchyard. This environment-friendly plant also complies with “zero liquid discharge” as it has systems installed for recycling and reuse of waste water in addition to low-NOx burners in the steam generator to curb NOx emissions.
With regard to fuel sources, NTPC has tied up fuel from its own captive coal mine, Pakri Barwadih, for the supply of 6.5 million tonnes per annum of coal. However, there is high demand for coal from other power plants as well. Thus, NTPC is exploring the possibility of getting coal from other sources to meet its requirement. It has already developed its own railway line of 37 km for coal transportation. So, as far as coal is concerned there are no major issues, notes NTPC. NTPC expects that the second unit will also be ready for generation in the current financial year. With commissioning activities in full swing, steam blowing is expected to start in the first week of November.
Apart from the 1,320 MW project at Khargone, NTPC is working on ultra supercritical power projects of around 6,000 MW at North Karanpura and Patratu in Jharkhand and Telangana. These units will have 3 per cent higher efficiency than a 500 MW conventional supercritical thermal plant using the same amount of coal.
According to Shailendra Roy, CEO and managing Director-L&T Power, and whole-time director-L&T, the market for ultra supercritical technologies is expected to remain robust going forward. “The central and state power utilities are graduating from supercritical to ultra supercritical technology for better efficiency in the form of lower cost of generation and lower emissions,” he comments.
L&T is currently executing a 2×660 MW ultra supercritical power project on an EPC basis in Bihar for SJVN Thermal Private Limited, a wholly owned subsidiary of SJVN Limited, which is a joint venture of the Government of India and the Himachal Pradesh government, and another 2×660 MW ultra supercritical power project (boiler and associated packages) for THDC India Limited. Two other power projects in the pipeline will also be based on ultra supercritical technology.
The retirement of old and inefficient thermal power plants that do not optimise precious resources is expected to drive the demand for ultra supercritical projects. “In the National Electricity Plan, around 48 GW of coal plants have been planned for retirement till the 2027 financial year. In the past three years, around 9 GW of coal-fired power plants have been retired, and supercritical units have been ordered or planned as their replacement. The pace of retiring the inefficient coal-fired plants needs to be increased with parallel focus on adding plants with ultra supercritical parameters,” adds Roy.
Overall, as India seeks to lower its emissions from its large coal fleet, ultra supercritical technologies will be the preferred option for the Indian power generation industry.