Common use of Design Basis Clause in Contracts

Design Basis. The Condensate System is designed to provide the maximum condensate demand during full load operation with both combustion turbines operating. The design capacity of each condensate pump will be based on supplying 50% of the maximum condensate flow to be encountered in operation, including turbine bypass. The pump shut-off head shall be a minimum of 115% of the total head at design flow and rated speed. The total head of the pump will be equal to the total discharge head minus the total suction head, plus 5% margin. The pumps shall be selected with 5% flow margin. Net positive suction head available (NPSHA) is zero at the pump suction flange. Each pump shall be designed such that the best efficiency point lies in the flow range between normal and maximum flow conditions. -------------------------------------------------------------------------------- Proprietary Information Page 20 AES IRONWOOD CONTRACT FINAL ISSUE - OCTOBER 30, 1998 -------------------------------------------------------------------------------- Modes of Operation During normal operation condensate feeds the HRSG, the steam jet air ejector condenser and gland steam condenser. Two 50% pumps will be running. During steam turbine bypass, the condensate system also feeds the reheat and LP bypass desuperheaters. In the event one of the condensate pumps shut down, the standby pump is automatically started to maintain the required flow. TYPICAL CONDENSATE PUMP DESIGN FEATURES Motor Driver Cast Iron Bowls A743 First Stage Impeller Bronze Impellers (Add'l Stages) Keyed Impellers 416 SS Pump Shaft Bronze Bearings 10LF-20 Fab Steel Discharge Head ▇▇▇▇ ▇▇▇▇▇ IB BF50 171 Mechanical Seal Plan 13 Seal Flush Piping - Copper Tubing 3 WSA Adjustable Spacer Coupling 300# RF Discharge Flange 150# RF Suction Flange Steel Suction Can Suction Can Vent Steel Mechanical Seal Housing 416 SS Headshaft Keyed Lineshaft Couplings -------------------------------------------------------------------------------- Proprietary Information Page 21 AES IRONWOOD CONTRACT FINAL ISSUE - OCTOBER 30, 1998 --------------------------------------------------------------------------------