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 Unitsii)The enclosure integral with boiler (except air heaters) shall be <strong>for</strong>med bywater/steam cooled tubes on all the four sides, ro<strong>of</strong> and bottom. Thefurnace water walls shall be <strong>for</strong>med using either spiral (helical) woundtubes or vertical plain/rifled tubes. The ro<strong>of</strong> <strong>of</strong> single pass/tower typeboilers could be <strong>for</strong>med by gas tight metal sheeting <strong>of</strong> appropriatematerial.iii) The enclosure shall be <strong>for</strong>med using welded wall construction only.Where use <strong>of</strong> refractory is unavoidable, 4mm thick steel plate behindrefractory shall be provided to <strong>for</strong>m enclosure.iv)Any penetration(s) into the steam generator enclosure shall be sealed <strong>for</strong>gas tight integrity.v) The Steam generator enclosure shall be provided with:a) Air cooled observation ports <strong>for</strong> each oil/coal burner and at variousplat<strong>for</strong>m levels on all the walls.b) Openings with hinged doors (air/gas tight) in all areas needing access<strong>for</strong> internal observation/maintenance. Minimum two openings <strong>for</strong>each area shall be provided.c) Approach plat<strong>for</strong>m <strong>for</strong> each observation port/opening alongwithladders from nearest plat<strong>for</strong>m level.d) Seal plates <strong>of</strong> stainless steel (type 430) or better corrosion anderosion resistant steel material <strong>of</strong> minimum 6 mm thickness, allround the furnace bottom, to prevent ingress <strong>of</strong> air.vi) Dissimilar metal welds (DMW) between martensitic and austeniticsteels, martensitic and ferrite steel shall be avoided inside the boilerenclosure <strong>for</strong> the pressure parts, which are exposed to hot flue gases.However, if such DMW are unavoidable, same can be permitted at shopprovided manufacturer has previous experience <strong>of</strong> such DMW andappropriate heat treatment is done after welding.vii) In the steam generator enclosure, minimum 1.5 m cavity height shall beprovided in between the horizontal banks/ sections <strong>of</strong> economizer,superheater and reheaters <strong>for</strong> maintenance purpose.viii) No ingress <strong>of</strong> air from any opening like bottom hopper, soot blower, anymanhole or peep hole, ducts etc. shall be considered <strong>for</strong> sizing <strong>of</strong>secondary and primary air fans while the same shall be considered <strong>for</strong>per<strong>for</strong>mance predictions.ix)Steam generator casing/pent house (as applicable) shall be provided. Thecasing/pent house design shall ensure:a) Complete enclosure <strong>of</strong> steam generator including superheater,reheater & economizer headers.30
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