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 Unitsc) Maximum allowable tubeskin temperatured) Means <strong>of</strong> temperaturecontrol:1. Superheaters2. Reheaters*40 0 C below oxidation metal limit <strong>for</strong> thetube metal.Spray water attemperation, (utilisingwater tapped <strong>of</strong>f from downstream side<strong>of</strong> HP heaters or intermediate banks <strong>of</strong>economizer or economizer outlet).Tapping <strong>of</strong> spray water upstream <strong>of</strong> topHP heater is not allowed.Tilting <strong>of</strong> burners/ gas biasing/ gasrecirculation (gas to be tapped <strong>of</strong>f afterID fans), spray water attemperation(utilising water tapped <strong>of</strong>f frominterstage <strong>of</strong> BFP).*Note: In case gas recirculation system is <strong>of</strong>fered <strong>for</strong> reheattemperature control, minimum 2x100% gas recirculation fans withatleast 20% margin on flow and 44% margin on head over calculatedmaximum requirement <strong>of</strong> fan flow and head respectively shall beprovided <strong>for</strong> each Steam Generator.ii) Construction <strong>of</strong> superheaters & reheaters shall have following features:a) Heating surfaces arrangements:1. Completely drainable tubes/ banks/ sections <strong>for</strong> SH/ RH tubebanks in case <strong>of</strong> tower type gas path arrangement. For the twopass boilers, the arrangement <strong>of</strong> SH/ RH banks shall have adrainable layout to the maximum possible extent.2. Banks/ sections/ tubes should be made from seamless tubes.3. In case <strong>of</strong> single fire vortex boiler, ensure even temperaturedistribution at gas and steam side by criss-crossing the steampaths between LHS and RHS.4. Use <strong>of</strong> girdling loops shall not be permitted except in case it isstandard practice <strong>of</strong> the manufacturer.5. Elements shall be uni<strong>for</strong>mly spaced to avoid gas bypassing.6. Use <strong>of</strong> radiant wall superheater shall not be allowed.Note: If design with radiant wall reheater is intended, the use <strong>of</strong>such radiant wall reheater shall be restricted to only on one <strong>of</strong> thefurnace walls (i.e. either on the front wall or on one <strong>of</strong> the sidewalls). Further, the lowest portion <strong>of</strong> wall RH shall not be below thefurnace nose tip level.38
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