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 Units6.4.5 Operation with HP and LP turbine bypass systemi) With HP-LP bypass system in operation, the unit shall be capable ofsmooth start-up, fast loading & house load operation.ii) Steam Turbine trip will call for boiler operation in HP/LP bypass mode.Under this condition, the boiler shall be capable of operating with SHflow corresponding to capacity of HP bypass system and feed watertemperature of approximately 140°C at economiser inlet.6.4.6 Mode of steam generator operation and rate of loadingi) As mentioned above, the Steam Generators shall be designed for variablepressure operation. Thermal design of Steam Generator and the selectionof materials of pressure parts shall be suitable for variable pressureoperational modes.ii) The Steam Generators shall be designed for minimum rate of loading/unloading mentioned below without compromising on design life ofpressure parts:a) Step load change : Minimum ±10%b) Ramp rate : Minimum ±3% per minute above 30% loadiii) The maximum rates of loading/ unloading achievable with SteamGenerator offered and the corresponding limiting variations (±%) of boilerparameters such as oxygen in flue gas, SH/RH steam temperature, furnacedraft, etc. shall be indicated.6.4.7 Steam generator control rangeThe automatic outlet steam temperature control range of Steam Generatorshall be from 50% TMCR to 100% BMCR for superheater as well as reheater.Under the above control range, the steam temperatures at SH & RH outletsshall be maintained at their rated values within allowable +/- 5°C temperaturevariation.6.4.8 Provision for future installation of FGD systemA flue gas desulphurization (FGD) system may be installed in future to meetthe requirements of pollution control. Following provisions need to be kept forthis purpose:i) Suitability of duct between ID fan and chimney for future interconnectionof FGD system with minimum modification.27

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsii) The ducting and supporting structure to be designed to take care of futureGuillotine damper to be installed between the two tap offs beforechimney.6.4.9 Limits of NO x emissioni) The guaranteed maximum NO x emission (thermal as well as fuel) fromthe Steam Generator unit shall not exceed 260 grams of NO x per GigaJoule (GJ) of heat input to the boiler at 6% O 2 level for the range of coalsspecified or as per MOEF’s requirement in this regard (if applicable)whichever is more stringent.ii) The above value of NO x shall not be exceeded during the entire operatingrange of Steam Generator for the whole range of specified coals.6.4.10 Capital overhaul of steam generatorThe design and materials for various equipments/auxiliaries etc. shall beselected keeping in view capital overhaul of units once in two (2) years, suchthat no major repairs/replacements, requiring shutdown of the unit, are neededin between the capital overhauls.6.4.11 Noise levelThe equivalent weighted average of sound level for continuously operatingequipment measured at a distance of 1.5 m above floor level in each elevationand one meter horizontally from the base of any equipments furnished,expressed in decibel to a reference of 0.0002 microbar, shall not exceed 85dB(A).6.4.12 Operational requirementThe Steam Generator(s) shall be designed for the following minimumoperational requirements at all loads and for the specified range of coal(s).i) Soot blowing frequency As per OEM’srecommendation forcharacteristics of the coalbeing firedii) Preferred mill combination Any combination of mills(without any restriction)iii) Max. coal flow unbalances in coal pipes 5.0%from same mill, from the averageiv) Slagging :a) Burnerb) In furnace/ash hopper/ water wall areasNilNilv) Maximum permissible reheat spray water 3% of steam flow atflow with rated steam temperature at reheater outletreheater outletvi) Maximum gas temperature variation 30 0 Cacross furnace width and depth28

<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 Units6.4.5 Operation with HP and LP turbine bypass systemi) With HP-LP bypass system in operation, the unit shall be capable <strong>of</strong>smooth start-up, fast loading & house load operation.ii) Steam Turbine trip will call <strong>for</strong> boiler operation in HP/LP bypass mode.Under this condition, the boiler shall be capable <strong>of</strong> operating with SHflow corresponding to capacity <strong>of</strong> HP bypass system and feed watertemperature <strong>of</strong> approximately 140°C at economiser inlet.6.4.6 Mode <strong>of</strong> steam generator operation and rate <strong>of</strong> loadingi) As mentioned above, the Steam Generators shall be designed <strong>for</strong> variablepressure operation. Thermal design <strong>of</strong> Steam Generator and the selection<strong>of</strong> materials <strong>of</strong> pressure parts shall be suitable <strong>for</strong> variable pressureoperational modes.ii) The Steam Generators shall be designed <strong>for</strong> minimum rate <strong>of</strong> loading/unloading mentioned below without compromising on design life <strong>of</strong>pressure parts:a) Step load change : Minimum ±10%b) Ramp rate : Minimum ±3% per minute above 30% loadiii) The maximum rates <strong>of</strong> loading/ unloading achievable with SteamGenerator <strong>of</strong>fered and the corresponding limiting variations (±%) <strong>of</strong> boilerparameters such as oxygen in flue gas, SH/RH steam temperature, furnacedraft, etc. shall be indicated.6.4.7 Steam generator control rangeThe automatic outlet steam temperature control range <strong>of</strong> Steam Generatorshall be from 50% TMCR to 100% BMCR <strong>for</strong> superheater as well as reheater.Under the above control range, the steam temperatures at SH & RH outletsshall be maintained at their rated values within allowable +/- 5°C temperaturevariation.6.4.8 Provision <strong>for</strong> future installation <strong>of</strong> FGD systemA flue gas desulphurization (FGD) system may be installed in future to meetthe requirements <strong>of</strong> pollution control. Following provisions need to be kept <strong>for</strong>this purpose:i) Suitability <strong>of</strong> duct between ID fan and chimney <strong>for</strong> future interconnection<strong>of</strong> FGD system with minimum modification.27

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