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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Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsd) Air heater drive 1. One (1) no. peripheral AC drive or central ACdrive as per OEM’s proven practice with gearbox and automatic clutching/ declutchingfacility.2. One (1) no. auxiliary air motor drive withautomatic clutching, declutching facility forrotation during non availability of A.C. drivesystem.3. An air receiver tank of storage capacityadequate to operate air pre-heater using airmotors for 10 minutes (minimum) with no airmake-up during this period.v) Two nos. inlet oil carryover detection probes shall be provided for eachAPH.6.5.9 Steam coil air pre-heaters (SCAPHs)i) SCAPHs shall be designed/ sized to increase the air heaters inlet airtemperature based on following criteria:a) Design ambient air 6 0 Ctemperatureb) Number of SCAPHs One (1) for each FD fan in case of trisectortype APH.orOne (1) for each FD fan and one (1) foreach PA fan in case of bi- sector typeAPH.c) Air temperature at 1. At 100% BMCR: 27 0 C (minimum).SCAPH outlet2. At 30% BMCR during oil firing:d) Air temperature at theinlet of each air preheater100 0 C (minimum).To keep average metal temperature(cold end) at least 76 0 C with coal firingand 100 0 C with oil firing.ii)SCAPH and connected air ducts shall be designed to handle flowscorresponding to 60% BMCR loads with one of the two streams workingwithout any undue noise/ vibration.6.5.10 Soot blowing systemi) Type of Soot Blowersa) For furnace chamber Short rotary, Single nozzle retractabletype.b) For horizontal heat 1. Long rotary, multiple nozzle,exchanger section retractable type for high temperaturezones.47

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units2. Short rotary, multiple nozzle,retractable type for low temperaturezones.c) Air-preheaters Power driven swinging arms soot blower,or retractable multi-nozzle soot blowers.ii)Soot blowing system shall be:a) capable of effectively removing deposited ash from steam generatorheat transfer surfaces with on- load cleaning devices. The sootblower design shall be of self draining type.b) fully automatic & sequentially controlled through SG C&I controlsystem. Alternately, a SMART Soot Blowing system based on heatflux sensors and flue gas exit temperature may be implemented witha fall back to sequential control, if required.iii)iv)The design of air-heater soot blowing system including piping, valves &fittings shall allow use of high temperature steam from high temperatureauxiliary steam header during start-up. A check valve and/or motoroperated valve shall be provided on this high temperature line to preventnormal soot blowing steam from entering auxiliary steam header. In casesoot blowing steam is required at parameters other than those availablefrom auxiliary steam system, for the purpose of efficient soot blowingduring start-up and other loads, a permanent arrangement shall beprovided for the same.Soot blower elements shall be made of extra heavy seamless tubing fromsolid bars with heat, corrosion & erosion protection in permanent contactwith hot gases. The Blowing element shall be of high temperature alloysteel.v) Retractable soot blowers (RSB) shall be retractable even duringemergencies such as drop in steam supply pressure, low steam flow, etc.Long retractable soot blowers (LRSBs) shall be half of steam generatorwidth on each side. Double helix cleaning pattern shall be used. Dualelectric drives, one for rotary and other for linear motion shall beprovided for each soot blower. Alternatively, soot blower design havingboth linear as well as rotary motion achieved through single drive motorshall also be acceptable.vi)All soot blowers shall be suitable for local and remote automaticsequential operation.6.5.11 Walkways, platforms and stairsi) Access platforms, walkways, handrails, stairs, ladders and gratings etc.for proper approach during maintenance shall be provided for steamgenerator, all auxiliaries, equipments and accessories. Walkways,48

<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 Unitsd) Air heater drive 1. One (1) no. peripheral AC drive or central ACdrive as per OEM’s proven practice with gearbox and automatic clutching/ declutchingfacility.2. One (1) no. auxiliary air motor drive withautomatic clutching, declutching facility <strong>for</strong>rotation during non availability <strong>of</strong> A.C. drivesystem.3. An air receiver tank <strong>of</strong> storage capacityadequate to operate air pre-heater using airmotors <strong>for</strong> 10 minutes (minimum) with no airmake-up during this period.v) Two nos. inlet oil carryover detection probes shall be provided <strong>for</strong> eachAPH.6.5.9 Steam coil air pre-heaters (SCAPHs)i) SCAPHs shall be designed/ sized to increase the air heaters inlet airtemperature based on following criteria:a) Design ambient air 6 0 Ctemperatureb) Number <strong>of</strong> SCAPHs One (1) <strong>for</strong> each FD fan in case <strong>of</strong> trisectortype APH.orOne (1) <strong>for</strong> each FD fan and one (1) <strong>for</strong>each PA fan in case <strong>of</strong> bi- sector typeAPH.c) Air temperature at 1. At 100% BMCR: 27 0 C (minimum).SCAPH outlet2. At 30% BMCR during oil firing:d) Air temperature at theinlet <strong>of</strong> each air preheater100 0 C (minimum).To keep average metal temperature(cold end) at least 76 0 C with coal firingand 100 0 C with oil firing.ii)SCAPH and connected air ducts shall be designed to handle flowscorresponding to 60% BMCR loads with one <strong>of</strong> the two streams workingwithout any undue noise/ vibration.6.5.10 Soot blowing systemi) Type <strong>of</strong> Soot Blowersa) For furnace chamber Short rotary, Single nozzle retractabletype.b) For horizontal heat 1. Long rotary, multiple nozzle,exchanger section retractable type <strong>for</strong> high temperaturezones.47

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