Standard Technical Features of BTG System for Supercritical 660 ...
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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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12.07.2015 Views

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsiv) Coolers (if applicable)a) 2x100% duty seal oil coolers.b) Cooler tube/ plate redundancy: Seal oilcoolers to be designed to have 15% excesscooling surface area over and above designedtube surface area required for the rated loadconditions, while maintaining the designpressure drop on cooling water side.v) Filters Suitable filters of 2x100% duty to beprovided.16.2.3 Stator water cooling systemi) General Cooling of stator winding to be provided witha closed loop stator water cooling system.a) Primary water tank One (1) no. tank mounted on generator casingwith anti-vibration pads or mountedseparately. The empty space in primary watertank may be filled with N 2 or H 2 (or air incase of oxygen rich type system) to minimizewater evaporation. Devices to be provided todetect, trap, monitor and release the H 2 thatleaks in to the stator water cooling system, toa safe place outside the building throughsuitable safety valves.b) Water to water heatexchangers2x100% or 3x50% capacity shell and tubetype or plate type water to water heatexchangers designed to accept secondary DMwater (condensate quality). The exchanger tobe designed to have 10% excess coolingsurface area over and above the designedsurface area required for the rated loadcondition, while maintaining the designpressure drop on cooling water side.c) Filters 2x100% capacity fine wire mesh filters withmagnet bars of unlimited life for removal ofall magnetic particles. Permanent magnet barsto be protected by sleeves of stainless steel.Alternatively, manufacturer’s standard andproven practice regarding type of filter shallalso be acceptable.d) Circulating waterpumps2x100% capacity AC motor driven.131

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitse) De-mineraliser One (1) mixed bed demineraliser (MBD) ofadequate capacity to maintain the requiredquality of water. MBD to remain continuouslyin service in order to retain high purity ofstator cooling water with its associatedelectrical resistivity.ii) On-line monitoringsystem for water qualityRequired for ensuring a corrosion freeoperation to be provided along with statorwater system.16.2.4 Generator excitation systemi) General The generator shall be provided with ‘StaticExcitation System’ or ‘Brushless ExcitationSystem’ along with ‘Automatic VoltageRegulator’.ii) Design and constructiona) General When the generator is subjected to a suddenloss of rated output at rated power factor, thesystem shall be capable of restoring thevoltage within 2% of the nominal preset valuewithin negligible time prior to initiation ofprotection equipment.b) Redundancy The redundancy shall be as follows :1. Static excitation system:Power thyristor converter shall be fullycontrolled three phase, full wave bridgetype with fast and high ceilingperformance. The converter shall have‘N+2’ redundancy where N is the numberof bridges required to deliver ratedexcitation current and ‘N+1’ number ofbridges shall deliver the ceiling voltage/current.2. Brushless Excitation System :- Converter assembly of pilot excitationsystem, thyristor gate firing system &pulse transformer shall have 2x100%redundancy.- The rotating rectifier assembly shall beof one complete bridge as redundant.Alternatively, a single three phaserectifier bridge with atleast oneredundant parallel branch in each of sixbranch of the bridge shall be provided.132

<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 Unitse) De-mineraliser One (1) mixed bed demineraliser (MBD) <strong>of</strong>adequate capacity to maintain the requiredquality <strong>of</strong> water. MBD to remain continuouslyin service in order to retain high purity <strong>of</strong>stator cooling water with its associatedelectrical resistivity.ii) On-line monitoringsystem <strong>for</strong> water qualityRequired <strong>for</strong> ensuring a corrosion freeoperation to be provided along with statorwater system.16.2.4 Generator excitation systemi) General The generator shall be provided with ‘StaticExcitation <strong>System</strong>’ or ‘Brushless Excitation<strong>System</strong>’ along with ‘Automatic VoltageRegulator’.ii) Design and constructiona) General When the generator is subjected to a suddenloss <strong>of</strong> rated output at rated power factor, thesystem shall be capable <strong>of</strong> restoring thevoltage within 2% <strong>of</strong> the nominal preset valuewithin negligible time prior to initiation <strong>of</strong>protection equipment.b) Redundancy The redundancy shall be as follows :1. Static excitation system:Power thyristor converter shall be fullycontrolled three phase, full wave bridgetype with fast and high ceilingper<strong>for</strong>mance. The converter shall have‘N+2’ redundancy where N is the number<strong>of</strong> bridges required to deliver ratedexcitation current and ‘N+1’ number <strong>of</strong>bridges shall deliver the ceiling voltage/current.2. Brushless Excitation <strong>System</strong> :- Converter assembly <strong>of</strong> pilot excitationsystem, thyristor gate firing system &pulse trans<strong>for</strong>mer shall have 2x100%redundancy.- The rotating rectifier assembly shall be<strong>of</strong> one complete bridge as redundant.Alternatively, a single three phaserectifier bridge with atleast oneredundant parallel branch in each <strong>of</strong> sixbranch <strong>of</strong> the bridge shall be provided.132

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