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

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsii) Number of standby mills a) At 100% of TMCR, : Oneworst coal firingb) At 100% BMCR, : Nilworst coal firingc) At 100% BMCR, : Onedesign coal firingiii) Sizing of coal pulverizers confirming to clause (i) and (ii) above shall beunder following conditions all occurring simultaneously:a) Maximum permissible millloading for deciding millcapacityb) Rated pulverized coalfineness at rated capacity ofthe pulverizer90% or the mill loading achievablecorresponding to the near worn outconditions of mill grindingrolls/balls/tyres etc. whichever isless. This condition shall becomplied for the range of specifiedcoals including the adequacy rangeof coals.Not less than 70% thru 200 mesh(75 microns) and 98% thru 50mesh (300 microns).8.5.3 Classifier designc) Input coal size Upto 50 mm.i) Static/ dynamic classifier capable of maintaining rated conditions offineness as specified under all conditions of operation, load changes andspecified fuels shall be provided. Further, the classifier vanes shall beadjustable externally.ii) Fineness adjustment shall be possible while the mills are in service.iii) Outlet shall be of aerodynamic shape to prevent eddies. The classifiervanes and cones shall be lined with wear resistant material to ensure theguaranteed wear life.iv) In case of static classifier, provision for accommodating rotary classifierin place of stationary classifier in future shall be made in the mill/ boilerdesign. For this purpose, necessary structure, pulverized coal piping, sparepiece etc. shall be provided.8.5.4 Adequate vibration isolation of mills shall be ensured so that no adverseaffects are transmitted to the nearby structure/installations.65