Standard Technical Features of BTG System for Supercritical 660 ...
Standard Technical Features of BTG System for Supercritical 660 ...
Standard Technical Features of BTG System for Supercritical 660 ...
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<strong>Standard</strong> <strong>Technical</strong> <strong>Features</strong> <strong>of</strong> <strong>BTG</strong> <strong>System</strong> <strong>for</strong> <strong>Supercritical</strong> <strong>660</strong>/800 MW Thermal Units1.1 <strong>Supercritical</strong> TechnologyCHAPTER 1INTRODUCTIONThe current thrust <strong>of</strong> thermal power development in the country is onsupercritical units so as to improve the conversion efficiency and reducecarbon footprint. A number <strong>of</strong> power generation utilities are going <strong>for</strong>supercritical technology and a large number <strong>of</strong> supercritical units <strong>of</strong> <strong>660</strong>/800MW size are already under construction. Apart from BHEL and L&T, severalother manufacturers are setting up facilities <strong>for</strong> manufacturing supercriticalboilers and turbine generators in the country. Considering these developments,this document on “<strong>Standard</strong> technical features <strong>for</strong> <strong>BTG</strong> system <strong>of</strong> supercritical<strong>660</strong>/800 MW thermal units” has been prepared with a view to evolve commonunderstanding amongst utilities, manufacturers and consultants on design andsizing philosophy <strong>for</strong> supercritical units. The objective is to incorporate broadfunctional aspects deemed necessary <strong>for</strong> specifying major quality andper<strong>for</strong>mance parameters unambiguously; and at the same time provideflexibility to the manufacturers. Steam generator and auxiliaries, being themajor focus area <strong>for</strong> supercritical units, have been dealt with in more detail.This document is not intended to be detailed specification <strong>for</strong> use as biddocument.The generation efficiency <strong>of</strong> coal fired stations depends on the steamparameters adopted - higher the steam parameters, higher is the efficiency. It iswith this objective that the steam parameters have been constantly raised from60 kg/cm 2 <strong>for</strong> 50 MW units to 170 kg/cm 2 <strong>for</strong> 500 MW units. <strong>Supercritical</strong>technology implies use <strong>of</strong> steam pressure beyond the critical point <strong>of</strong>water/steam which is about 225 kg/cm 2 . Thus, supercritical units use highersteam parameters <strong>of</strong> over 240 kg/cm 2 with various combinations <strong>of</strong>temperature and pressure. This has been made possible largely throughdevelopments in materials technology to withstand the higher temperaturesand pressures in the boiler.World over the supercritical technology has been driven by the need toachieve higher efficiency in order to reduce specific fuel consumption andgreen house gas emissions. <strong>Supercritical</strong> technology is an established andproven technology with over 500 supercritical units operating worldwide andreliability and availability <strong>of</strong> supercritical units being at par with that <strong>of</strong> subcriticalunits. Ultra supercritical parameters with pressure <strong>of</strong> 250-300 kg/cm 2and main steam/ reheat steam temperatures <strong>of</strong> 600/610 0 C are also beingadopted. Research is underway to further increase the steam temperatures to700 0 C.Whilst the earlier supercritical units installed in the country adopted steamparameters <strong>of</strong> 247 kg/cm 2 , 535/565 0 C, higher steam parameters <strong>of</strong> 247 kg/cm 2 ,565/593 0 C are being adopted <strong>for</strong> later units and have been adopted in this1
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