Condensate (CD) Flashcards
Purpose of the Condensate system
Provides heat sink for Turbine, Feedwater pumps, steam bypass control
Minimize air in-leakage
Chemistry control
Provide suction to FWP’s
Where is the dog bone seal filled from if we need to fill it with water?
Condensate service header
How are the Equalization ducts filled?
Condensate service header
How would the equalization duct water seal blow out?
Seal will blow out if differential temperature 30*F
What is the main cause of vacuum in the condenser?
phase change of steam coming from the LP turbines condensing
What is the purpose of the Hotwells in the main condenser?
One in each condenser section (2 hotwell halves)
100,000 gal. Volume, sufficient for 4 minutes of operation at ‘valves wide open’ condition.
Provide:
Condensate storage
Reheat and deaeration
Detention time
Leak detection
Which hotwell halves do the CD pumps take suction from?
Pump A - hotwells 2A/B/C
Pump C - hotwells 1A/B/C
Pump B - both sides of hotwell
What is the purpose of the mini-flow recirc valves for the CD pumps?
prevent overheating of the pump at reduced flow
Where do the CD pump mini-flow recirc valves direct flow back to?
Pump A - hotwell 2C
Pump C - hotwell 1C
Pump B - 1C and/or 2C depending on suction valve alignment
What type of controllers are provided for the CD pumps?
Foxboro controllers (B05)
CDN-LIC-81/82
What level is the Condenser normally maintained at?
Why?
41”
Basis is on a Heater Drain Pump trip, we could lose 9 inches of level in the hotwell.
The Condensate Pumps trip on a lo-lo level of 30 inches
This gives us margin
What type of valve operator is on the auto makeup valves?
How do they fail?
Where do they flow into directly?
2 AOV’s
fail closed on a loss of air or NK
‘A’ Condenser shell, 140’ TB
If the CST Lo-Lo setpoint is reached, what happens to auto makeup to the Main condenser?
solenoid valve isolates air to the auto makeup valves to isolate the CST auto makeup
What is the motive force for auto makeup to the main condenser from the CST?
vacuum drag
very low pressure in the condenser, higher pressure in the CST
What is the purpose of hotwell draw off?
Hi-level in hotwell, will cause CDN-LV-75 to open and send water to CST
When does CDN-LV-75, Hotwell draw off valve, automatically close?
Why?
How can these interlocks be overridden?
low feedpump suction pressure
–to help with saving a feedpump from tripping on low suction pressure
high cation conductivity
–minimize CST contamination
Key switch in ZTN-C01, HS-75
What type of valve operator is on CDN-LV-75, hotwell draw off valve?
How does it fail?
air operated valve
fails closed on a loss of air
What is special about the draw off valve interlock bypass switch in the ZTN-C01 cabinet (HS-75)?
key switch, captures the key in bypass position
key in SM office
What is needed administratively before overboarding condensate?
Why?
overboard permit
so chemistry can verify water contamination is within release limits
Which CD pumps can be used for overboarding?
A and C ONLY
What is the purpose of long path recirculation?
initial cleaning up during startup and shutdown
What is the flow path for long path recirculation?
1 CD pump takes suction on the hotwells > CD demins > 3 strings of LPFWHs > Feedpump bypass > HPFWHs > V124/V125 > HV-46/VA31 > back to the condensers
What is the issue caused by the HV-46 valve not having a ‘jog’ function?
What plant mod fixed this?
caused thermal shock and water hammering
2” bypass line around HV-46 with VA31 to better control cooldown
What is the prerequisite for opening HV-46 while going into long path recirculation flow?
HPFWH #7 feedwater outlet temperature has to be </= 200*F
