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 Unitsg) If the Steam Generator has the flue gas down-flow section withhorizontal tube banks, the top most row shall be shielded to reduceerosion.h) Headers shall be located external to gas path and shall be completelydrainable. If locating headers in gas path becomes unavoidable, thansuitable erosion shields/ protectors must be provided.i) Economiser shall be provided with ash hoppers along with high ashlevel switches/ alarms, if economizer is placed in the second pass <strong>of</strong>Steam Generator.j) Wet ash handling system is intended <strong>for</strong> evacuation <strong>of</strong> ash collectedin the economizer & economizer bypass hoppers (if applicable).Sufficient head room below the economizer/ economizer bypasshoppers shall be ensured to accommodate the ash handlingequipment. A minimum headroom <strong>of</strong> 2.5 m shall be kept betweenhopper flange and plat<strong>for</strong>m to accommodate the ash handlingequipments. To enable the ash/slurry pipes from economizer/economizer bypass hoppers to be routed with minimum bends, itmay be required to pass vertically through the air/ flue gas ducts. Insuch a case it is envisaged that a pipe sleeve shall be providedwithin the ducts through which the ash/ slurry pipes may be routed.iii) Economizers shall also meet following requirements:a) Minimum 1.5 m clear cavity height between two sections/banks <strong>of</strong>the economizer <strong>for</strong> maintenance access.b) Access /opening <strong>for</strong> each tube banks alongwith air/ gas tight hingeddoors.c) Arrangement (structural steel/runway beams, motorized hoists,walkways plat<strong>for</strong>m alongwith runway beams etc.) <strong>for</strong> removing,handling and placement <strong>of</strong> tubes banks/section at ground level <strong>for</strong>repair/ replacement. The size <strong>of</strong> plat<strong>for</strong>ms shall be adequate to store5-6 economizer assemblies as well as adequate space <strong>for</strong> handlingthem.d) Arrangement <strong>for</strong> <strong>of</strong>f load water washing <strong>for</strong> economizer withnecessary drainage connected to nearest drain, if two pass boiler is<strong>of</strong>fered.e) The header shall be provided with drains and suitable opening with<strong>for</strong>ged weld on caps <strong>for</strong> internal inspection and chemical cleaning.Inspection openings with <strong>for</strong>ged weld on caps shall be provided <strong>for</strong>headers.44
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