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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<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 UnitsFurnace residence time shall be calculated by dividing the furnacevolume between the center line <strong>of</strong> top coal burner and furnace exitplane by the flue gas volume at mean gas temperature in the abovefurnace volume.iii) Furnace/ evaporator shall be designed <strong>for</strong> variable pressure operationover 30% to 100% BMCR load range.iv)Water/ steam walls shall be <strong>of</strong> membrane wall construction and shall bemade <strong>of</strong> seamless tubes. Furnace/ evaporator shall be <strong>for</strong>med using spiralwound/ inclined tubing or vertical plain/ rifled tubing as per the provenpractice <strong>of</strong> the manufacturer <strong>for</strong> boilers <strong>of</strong> similar capacity. Irrespective<strong>of</strong> the type <strong>of</strong> water wall tubing <strong>of</strong>fered <strong>for</strong> the evaporator, the design<strong>of</strong>fered shall ensure that no readjustment <strong>of</strong> tube mass flow is requiredduring entire operating regime <strong>of</strong> the steam generator <strong>for</strong> complete range<strong>of</strong> specified coals. In case such readjustment becomes necessary over aperiod <strong>of</strong> five years from the date <strong>of</strong> successful completion <strong>of</strong> initialoperation <strong>of</strong> respective steam generator, the same shall be carried out bythe supplier. Appropriate time required <strong>for</strong> readjustment and period <strong>of</strong>shut down shall be indicated.v) Elevation <strong>of</strong> Furnace Bottom Hopper shall be at least 10.25 m abovegrade level <strong>for</strong> wet bottom ash handling system and opening <strong>of</strong> bottomhopper shall be 1.10 m (minimum) wide.vi) A minimum allowance <strong>of</strong> 0.6 mm over and above the calculatedthickness as per IBR shall be provided <strong>for</strong> entire water wall. Anadditional tube thickness <strong>of</strong> 1.0 mm over and above the tube thickness <strong>of</strong>water wall tubes calculated as per above shall be provided on all waterwall tubes coming within a radius <strong>of</strong> one meter around each wall blowerto guard against premature tube failure due to soot blowing steamerosion.vii) Flame impingement on steam/ water walls is not permitted.viii) Maximum allowable tube skin temperature <strong>for</strong> evaporator section shallbe 40 0 C below oxidation limit <strong>for</strong> tube metal.ix) Headers shall be located external to gas path and shall be completelydrainable. If locating headers in gas path becomes unavoidable, thensuitable erosion shields/ protectors must be provided.x) Minimum 10 mm dia. wear bars <strong>of</strong> suitable wear resistant material shallbe welded along the full length <strong>of</strong> first 40 tubes <strong>of</strong> inclined water walltubes <strong>of</strong> S-panel <strong>of</strong> bottom hopper from each corner up to hopperopening or adequate additional thickness shall be provided to take care<strong>of</strong> erosion.34
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