Power Generation

FeedwaterSystem

O&M Training 2For Training Only

Feedwater System

Provides deaerated and preheated feedwater to the HRSG HP and IP steam drumsSupply feedwater to various desuperheaters and to the condensate preheater system.

Functions

IP desuperheaterHP desuperheater

HP reducingstation

IP HP

from CEP

Keep Min. flow of feedwater

Pump

Provide injection water for IP-

desuperheater

Supply feedwater from condensate

preheater to IP- and HP drums via IP- and

HP- economizers

Provide injection water for HP-desuperheater and reducing

station

Provide extracted

feedwater for condensate preheating

O&M Training 3For Training Only

Feedwater System

HP Feedwater to HP Economizer (~ 1000 gpm at 4475 feet of differential head)HP Feedwater to HP Superheater AttemperatorHP Feedwater to the HP ST By-pass Station HP and IP Feedwater to the Sampling System HP Feedwater Minflow to Condensate System

IP Feedwater to IP Economizer (~ 175 gpm at 1183 feet of differential head) IP Feedwater to Reheater Attemperator

LP Take-off to Condensate Recirculation (~ 350 gpm at 252 feet of differential head)

Drains and Vents to the Drain System

Functions

O&M Training 4For Training Only

Feedwater System

PT PT

610 PSIG 610 PSIG

PT

PT TT

PT

STRAINERSTRAINER

ARCVALVE

ARCVALVE

BFP BFP

IP DRUM

CONDPRHTR

HP DRUM

O&M Training 5For Training Only

Feedwater Pump

Designed to provide adequate flow rates at required pressure for startup, shutdown, normal and ST bypass operation. Takes suction from the condensate preheater (CPH). Min flow line discharges to the main condensate line upstream of the CPH.

Design featuresHorizontal, radial split, ring-section pump with radial impellers, single-flow entryMotor-driven, constant speed 1750 Hp, 6600 VAC, 3 phase, 60 IP feedwater and condensate recirculation extractionY-type suction strainerAutomatic recirculation valve (min. flow) for pump protection (one valve per pump)Supply for both HRSGsIntegral self contained lubrication sys (brg oil sump)Oil Slinger Ring SystemOil cooler cooled by CCW

Design

O&M Training 6For Training Only

Boiler Feedwater Pump

O&M Training 7For Training Only

Boiler Feedwater Pump

FeaturesShaft seals located at each End of the pumpCCW supplies cooling water to these shaft seals.Each Closed Cooling Water return line and bearing oil return line has a flow indicatorProper axial shaft positioning – accomplished with a lift off device and a Balance Piston. Lift off device – Uses a spring to provide a small amount of thrust on the shaft for proper axial shaft positioning on pump startup. Balance piston provides for proper axial shaft position in the pump casing after startup

O&M Training 8For Training Only

Feedwater Pump

Self Actuating Relief Valve @ 610 psig

Minimum Flow Recirculation Control Valve (ARC Valve)Provides a minimum of 431 gpm flow through the pump Prevent overheating and cavitation during startup and low flow operation. Proportional type valveEach ARC valve contains a check valve to prevent backflow through an idle pump.

Suction Relief Valve

O&M Training 9For Training Only

Walk down the pump and system. Inspect for:Proper valve lineups,Correct oil levelsMotor breaker closed.

Feedwater Pump Protection Off (Trip)The feedwater pumps will shut off on

Protection if any of the following conditions occur:

Loss of HP/IP FWP Required NPSH, ORHP/IP FW Pmp Non Drive End High High Bearing Temp > 82°C (180°F) ORHP/IP FW Pmp Drive End High HighBearing Temp > 82°C (180°F) ORHP/IP FW Pmp Non Drive End High Vibration (6 mils) ORHP/IP FW Pmp Drive End High Vibration (6 mils) ORHP/IP FW Pmp discharge pressure low – HP < 113 bar (1639 psig), IP < 26 bar (377 psig) for longer than 20 seconds No CEP Running

Prestart Requirements

Feed Pump Operation

O&M Training 10For Training Only

Feed Pump Operation

O&M Training 11For Training Only

Feed Pump Operation#1 SLC / ASO Start Feedwater Pumps

Operator must initiate a start up of the feedwater system. From the OM Screen, Operator turns ON the “SLC START FEEDWATER PUMPS”

SLC START FEEDWATER PUMPS - ON, “Feedwater Pump – In Auto. Commands Selected Feedwater Pump – ON if enable signals satisfied.

O&M Training 12For Training Only

Feed Pump Operation#1 SLC / ASO Start Feedwater Pumps

The feedwater pumps are enabled to start if: Condensate Preheater Trim Valve (11LCA30AA101) is >19% Open ANDAt least One CEP is Running ANDCEP Common Discharge Pressure > 23.56 bar (342 psig) AND At least One Circ Water Pump is Running ANDFeedwater Pump Drive End Vibration Alarm is NOT Active (<4 mils) ANDFeedwater Pump Non-Drive End Vibration Alarm is NOT Active (<4 mils) ANDFeedwater Pump NPSH Required to Start is Satisfied ANDBoth HP and IP Feedwater Block Valves Closed or Other Feedwater Pump in Operation ANDNo Feedwater Pump Trip Active

O&M Training 13For Training Only

Feed Pump Operation#1 SLC / ASO Start Feedwater Pumps

Standby Pump START Command: Commanded pump fails to start:

Start command active > 20 seconds and HP discharge pressure < 113 bar (1639 psig) or IP discharge pressure is < 26 bar (377 psig), ORHP or IP feedwater flow increases to greater than a set value (HP – 60 kg/s, IP – 71 kg/s).

“2nd BFWP Not Needed” Alarm - Activated: Both feedwater pumps – RunningBoth HP flow (<52 kg/s) and IP flow (<61 kg/s) for > 20 sec

“2nd BFWP Not Needed” Alarm - Informs operator to turn off the standby pump