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 Unitsg) Minimum dust- eight (8)hopper storagecapacity (upto themaximum trip levelbased on designpoint conditions(while firing worstcoal (with maximumash) (in hrs)h) Minimum hopper Sixty (60) Sixty (60)valley angle to thehorizontal (degrees)i) Maximum nos. of Two (2) for one TR Two (2) for one TRash hoppers setset* Collecting plate spacing of 400 mm may also be allowed with referenceminimum sca as 195 m 2 /m 3 /s (calculated from sca of 260 m 2 /m 3 /s for 300mm spacing as per inverse proportion of spacing between collecting plates).10.2 System DescriptionThe ESPs shall be of outdoor type and installed on the cold end side ofregenerative air pre-heaters. The flue gas shall be drawn from air pre-heateroutlets and guided through adequately sized duct work into the specifiednumber of independent gas streams of the ESP. Similarly, the flue gas after theESP shall be led to the suction of the induced draft fans. The flue gastemperature may approach the economiser outlet temperature in case theregenerative air pre-heaters fail to operate. These aspects shall be taken intoaccount while designing the ESPs.10.3 Service ConditionsThe steam generators are to be designed to burn HFO/HPS/LSHS and LDO inconjunction with pulverised coal during startup and at low loads for warm upand flame stablisation. Further, the frequency and durations for startup andlow loads operation may be quite large during unit commissioning and firstyear of operation. The entire characteristics of expected combination of fuelsto be fired shall be taken into account and preventive measures shall beprovided to minimise the possibility of fires in the ESPs and to avoid thecorrosion of ESP components/ surfaces.10.4 Location and Layout RequirementsESP control room shall be located at grade level adjacent to the ESP and shallhouse the control cubicles. The Man Machine Interface (MMI) to be providedto enable unit control room operator to access the ESP controls for control,monitoring and data acquisition functions may be suitably located in the unitcontrol room.81

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Units10.5 Maintenance Requirements10.5.1 The design of the precipitators shall allow adequate space above and betweenthe adjacent fields to carryout necessary inspection and maintenance. Apermanent walkway shall be provided at each rapper level both for thedischarge and collecting plates.10.5.2 Minimum 2.0 m wide platforms shall be provided between the two casings ofthe ESPs to facilitate maintenance work and minimum 1.2 m wide platformshall be provided all around all ESP passes at intermediate and TR setelevation. The protection for the platform and the rapping motors fromexposure to rain shall also be provided.10.5.3 One staircase of minimum 0.85m clear width shall be provided between twoadjacent streams (casings) from ground to the roof of the ESPs with landingsconnected at all platforms. As such, minimum three (3) staircases shall beprovided for ESP of 660 MW unit and five (5) staircases for ESP of 800 MWunit. Two adjacent staircases shall be located on opposite ends of the ESP.Further, the platforms between all the ESP casings shall be interconnected atleast at one intermediate elevation.10.5.4 Each compartment of individual stream of ESP shall be provided withisolation dampers at inlet and outlet for carrying out maintenance work whilethe remaining streams of ESP are in service by completely isolating itelectrically and grounding it. Suitable safety interlocks etc. shall be provided.10.5.5 A monorail system with movable trolley and an electrically operated hoistmounted on the precipitators roof shall be provided for handling andmaintenance of TR sets, rapper motors, fans (if applicable) etc. By thisarrangement, it shall also be possible to lower the TR sets down to the groundlevel and/or onto a truck. Normal and special maintenance tools shall also befurnished for attending to different equipment.10.6 Model StudyComputer based model study using CFD technique or physical flow modelstudy shall be carried out to achieve optimum size and layout of the ducting,uniform flue gas distribution, maximum particulate collection, minimum draftloss, minimum dust drop out and build up and minimum re-entrainment fromwithin the precipitator. The design of the duct work, guide vanes, flow splittersetc. shall be finalized based on results of the model study. The model studyshall also include a gas distribution study for the duct system around ESP tofind out the effect of isolation of one stream of the ESP. CFD model study orphysical flow model study for the ESP may not be needed in case the same hasbeen earlier carried out for similar size and type of the ESP.10.7 Gas Distribution SystemGas distribution system shall be provided at the precipitator inlet as well asoutlet sections to achieve uniform gas distribution throughout the ESP with82

<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 Unitsg) Minimum dust- eight (8)hopper storagecapacity (upto themaximum trip levelbased on designpoint conditions(while firing worstcoal (with maximumash) (in hrs)h) Minimum hopper Sixty (60) Sixty (60)valley angle to thehorizontal (degrees)i) Maximum nos. <strong>of</strong> Two (2) <strong>for</strong> one TR Two (2) <strong>for</strong> one TRash hoppers setset* Collecting plate spacing <strong>of</strong> 400 mm may also be allowed with referenceminimum sca as 195 m 2 /m 3 /s (calculated from sca <strong>of</strong> 260 m 2 /m 3 /s <strong>for</strong> 300mm spacing as per inverse proportion <strong>of</strong> spacing between collecting plates).10.2 <strong>System</strong> DescriptionThe ESPs shall be <strong>of</strong> outdoor type and installed on the cold end side <strong>of</strong>regenerative air pre-heaters. The flue gas shall be drawn from air pre-heateroutlets and guided through adequately sized duct work into the specifiednumber <strong>of</strong> independent gas streams <strong>of</strong> the ESP. Similarly, the flue gas after theESP shall be led to the suction <strong>of</strong> the induced draft fans. The flue gastemperature may approach the economiser outlet temperature in case theregenerative air pre-heaters fail to operate. These aspects shall be taken intoaccount while designing the ESPs.10.3 Service ConditionsThe steam generators are to be designed to burn HFO/HPS/LSHS and LDO inconjunction with pulverised coal during startup and at low loads <strong>for</strong> warm upand flame stablisation. Further, the frequency and durations <strong>for</strong> startup andlow loads operation may be quite large during unit commissioning and firstyear <strong>of</strong> operation. The entire characteristics <strong>of</strong> expected combination <strong>of</strong> fuelsto be fired shall be taken into account and preventive measures shall beprovided to minimise the possibility <strong>of</strong> fires in the ESPs and to avoid thecorrosion <strong>of</strong> ESP components/ surfaces.10.4 Location and Layout RequirementsESP control room shall be located at grade level adjacent to the ESP and shallhouse the control cubicles. The Man Machine Interface (MMI) to be providedto enable unit control room operator to access the ESP controls <strong>for</strong> control,monitoring and data acquisition functions may be suitably located in the unitcontrol room.81

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