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 Unitsii)iii)iv)Steam tight horizontal joints with metal to metal contact or as per provenpractice <strong>of</strong> the manufacturer.All extractions shall preferably be from the lower half <strong>of</strong> casing andextraction branches shall be welded to casings except <strong>for</strong> LP casing(s)extractions which can be with either welded type or bolted typeconnection as per turbine manufacturer’s standard practice.Adequate drainage facility with temperature devices (in pair) shall beprovided in casings, strainer- housings, stop and control valves,extraction lines etc. with provision <strong>for</strong> water detection and properremoval during start-up and shall be in accordance to ASME TDP-1.v) Pressure relief bursting diaphragm <strong>for</strong> LP casing(s) to limit the exhausthood pressure within a safe margin from design pressure.vi)A completely self contained exhaust hood spray system shall beprovided <strong>for</strong> LP casing(s) to protect the turbine against excessivetemperature due to windage at no load / low load and HP/LP by passoperations.12.3 Turbine Rotor12.3.1 Rotor shall be <strong>of</strong> <strong>for</strong>ged alloy steel.12.3.2 Maximum permissible shaft vibration measured at bearing housing shall beas per zone A <strong>of</strong> ISO 7919 and maximum permissible bearing vibrationmeasured at bearing housing will be as per zone A <strong>of</strong> ISO 10816-2.12.3.3 Critical speed <strong>of</strong> composite rotor and blade assembly shall not be within(-)10 % to (+)15% <strong>of</strong> the operating speed.12.4 Nozzles and Blades12.4.1 Nozzles and blades shall be made from hard, corrosion & erosion resistantalloy steel.12.4.2 LP blades design without lacing wires is preferred. TheLP last stage blades shall be designed <strong>for</strong> effective removal <strong>of</strong> moisture.12.4.3 Hardening <strong>of</strong> LP last stage blades upto 1/3 rd (minimum) <strong>of</strong> blade length &width 25mm (minimum) or stelliting or design <strong>of</strong> LP last stage blades withprovision <strong>of</strong> moisture removal as per the proven standard practice <strong>of</strong> OEMshall be provided.12.4.4 There shall be no resonance <strong>of</strong> LP blading in the continuous operatingfrequency range <strong>of</strong> 47.5 Hz to 51.5 Hz.91
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