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

Standard Technical Features of BTG System for Supercritical 660/800 MW Thermal Unitsiv) Shaft sealing Either mechanical seals or packed type withexternal water sealing designed to preventair ingress to condenser even when thepump under shut down and exposed tocondenser.v) Impeller/Casing design Closed and nonover-loading type impellerwith wear rings on pump bowls.vi) Materials a) Suction bell/pump casing : Cast Iron.b) Impeller/ wear rings/shaft/ shaft sleeves :12%Cr stainless steel.c) Cannister : Fabricated mild steel.vii) Pump Sizinga) Design Capacity Combined flow of 2 x 50 % CEP to bebased on 10% margin over highestcondensate flow envisaged during unitoperation (excluding HP/ LP bypassoperation).b) Design Head The design head shall be worked outconsidering minimum 10% margin in pipingfriction for highest condensate flow as at (i)above and 10% margin over maximumdeaerator pressure.c) Best efficiency point Combined flow of 2x50% CEPs shall bebased on TMCR requirementand corresponding head.d) Maximum Capacity One pump shall be capable of handling theflow and head corresponding to 65% unitload.e) Other Capabilities 1. Two pumps shall be capable of handlingthe flow corresponding to Unit TMCR,all HP heaters out, 1% make up andworst condenser pressure at 47.5 Hz.2. Two pumps shall be capable of handlingthe flow corresponding to HP - LP bypass operation with turbine under trippedcondition as well as turbine on houseload.f) NPSH Margin NPSH (R) at 3% head drop shall not bemore than half the NPSH(A) at design flowwith low low hotwell level and NPSH(R) at3% head break shall be well belowNPSH(A) under all conditions.104