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LOIT > Condensate (CD) > Flashcards

Condensate (CD) Flashcards

1
Q

Purpose of the Condensate system

A

Provides heat sink for Turbine, Feedwater pumps, steam bypass control
Minimize air in-leakage
Chemistry control
Provide suction to FWP’s

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2
Q

Where is the dog bone seal filled from if we need to fill it with water?

A

Condensate service header

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3
Q

How are the Equalization ducts filled?

A

Condensate service header

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4
Q

How would the equalization duct water seal blow out?

A

Seal will blow out if differential temperature 30*F

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5
Q

What is the main cause of vacuum in the condenser?

A

phase change of steam coming from the LP turbines condensing

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6
Q

What is the purpose of the Hotwells in the main condenser?

A

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

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7
Q

Which hotwell halves do the CD pumps take suction from?

A

Pump A - hotwells 2A/B/C
Pump C - hotwells 1A/B/C

Pump B - both sides of hotwell

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8
Q

What is the purpose of the mini-flow recirc valves for the CD pumps?

A

prevent overheating of the pump at reduced flow

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9
Q

Where do the CD pump mini-flow recirc valves direct flow back to?

A

Pump A - hotwell 2C
Pump C - hotwell 1C

Pump B - 1C and/or 2C depending on suction valve alignment

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10
Q

What type of controllers are provided for the CD pumps?

A

Foxboro controllers (B05)

CDN-LIC-81/82

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11
Q

What level is the Condenser normally maintained at?

Why?

A

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

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12
Q

What type of valve operator is on the auto makeup valves?

How do they fail?

Where do they flow into directly?

A

2 AOV’s

fail closed on a loss of air or NK

‘A’ Condenser shell, 140’ TB

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13
Q

If the CST Lo-Lo setpoint is reached, what happens to auto makeup to the Main condenser?

A

solenoid valve isolates air to the auto makeup valves to isolate the CST auto makeup

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14
Q

What is the motive force for auto makeup to the main condenser from the CST?

A

vacuum drag

very low pressure in the condenser, higher pressure in the CST

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15
Q

What is the purpose of hotwell draw off?

A

Hi-level in hotwell, will cause CDN-LV-75 to open and send water to CST

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16
Q

When does CDN-LV-75, Hotwell draw off valve, automatically close?

Why?

How can these interlocks be overridden?

A

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

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17
Q

What type of valve operator is on CDN-LV-75, hotwell draw off valve?

How does it fail?

A

air operated valve

fails closed on a loss of air

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18
Q

What is special about the draw off valve interlock bypass switch in the ZTN-C01 cabinet (HS-75)?

A

key switch, captures the key in bypass position

key in SM office

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19
Q

What is needed administratively before overboarding condensate?

Why?

A

overboard permit

so chemistry can verify water contamination is within release limits

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20
Q

Which CD pumps can be used for overboarding?

A

A and C ONLY

21
Q

What is the purpose of long path recirculation?

A

initial cleaning up during startup and shutdown

22
Q

What is the flow path for long path recirculation?

A

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

23
Q

What is the issue caused by the HV-46 valve not having a ‘jog’ function?

What plant mod fixed this?

A

caused thermal shock and water hammering

2” bypass line around HV-46 with VA31 to better control cooldown

24
Q

What is the prerequisite for opening HV-46 while going into long path recirculation flow?

A

HPFWH #7 feedwater outlet temperature has to be </= 200*F

25
Q

What is the purpose of the vacuum breakers?

How are they operated?

A

allows a rapid slowing of the turbine under emergency conditions

solenoid provides air to open, spring to close

26
Q

Why do we keep a water seal on top of the vacuum breaker valve disk?

where does the seal water come from?

A

prevents air leakage into condenser

condensate service header

27
Q

What is the capacity of the CD pumps?

A

50% each, but keep all three running normally

28
Q

What cools the CD pump motor bearing oil?

A

TC

29
Q

What is the hotwell low level trip for the CD pumps?

A

30”

30
Q

Where is each CD pump powered from?

A

Pump A and B - NBN-S01
Pump C - NBN-S02

31
Q

How is the CD pump seal cooled and lubricated?

A

flow from the condensate service header

32
Q

CD pump interlocks and trips

A

suction valve needs to be full open or breaker wont close
pump B needs at least one suction valve open

pump trips:
30” or less in the hotwell pump is aligned to
Low flow less than 3600 gpm for greater than 45 seconds
4.16 kV bus undervoltage
Lockout relay

33
Q

How much flow are CD pump mini-flow recirc valves capable of passing?

When do they start to modulate open?

A

4000 gpm

CD pump flow decreases to 4500 gpm

34
Q

How do they CD pump mini-flow recirc valves fail?

Where do they get power from?

A

AOV

fail open on a loss of air or NN

pump A and C mini-flow valves from NNN-D11
pump B mini-flow valves from NNN-D12

35
Q

What is the negative result of CD pump mini-flow valves failing open?

A

reduced FWP suction pressure

36
Q

What are the CD pump B mini-flow valves interlocked with?

A

B pump suction valves

whichever suction valve is open determines which mini-flow valve will modulate to go back to the same hotwell half group that the pump is taking suction on
(normally both are utilized)

37
Q

What kind of controller (reverse or direct acting) does CDN-PDV-195, Condensate Polishing Demineralizer bypass valve, have?

A

reverse acting

0% output - Open
100% output - Closed

meaning it fails open on loss of air

38
Q

What is the purpose of CDN-PDV-195, Condensate Polishing Demineralizer bypass valve?

A

direct flow around the CD Demins

maintains 55 psid or less when demins are inservice

39
Q

What are the permissives for opening CDN-PDV-195, Condensate Polishing Demineralizer bypass valve?

A

Both inlet and outlet valves must be open for an modulate permissive of bypass

40
Q

What 3 signals will open CDN-PDV-195, Condensate Polishing Demineralizer bypass valve, even when the controller is in manual?

A

Condensate polishing inlet or outlet valve not fully open

Condensate demineralizer high differential pressure (greater than 55 psid)

Instrument Air header pressure low

41
Q

What loads does the Condensate service header supply?

A

condenser expansion joint (dog bone seal), vacuum breakers, and air removal pumps

42
Q

What controls Condensate Service Header pressure?

What pressure is it maintained at?

How does this valve fail?

A

air operated PCV (CDN-PV-200)

80psig

fails closed on a loss of air

43
Q

What is the backup supply to the condensate service header?

A

DW through valve DWN-HV-275

44
Q

How is Steam bypass control system tied into the CD system?

A

SBCVs 1001-1006 discharge to the main condenser shells

45
Q

What is special about the CD pump discharge valve handswitches in the control room?

A

push to stop feature on the handswitch

when pushed, it stops the valve movement at whatever position it is currently in

46
Q

How many demin beds are inservice during full flow operation?

A

5 beds inservice with one being regenerated

47
Q

How are the LPFWH inlet and outlet valves controlled?

A

handswitch in the control room opens/closes them both at the same time

48
Q

How does the Main Turbine system tie into the CD system?

A

CD provides hood spray

helps cool the LP turbine hoods and help direct steam down towards the condenser

49
Q

The CD pumps trip on a hotwell level of 30”, but when does the alarm come in?

A

34”

LOIT (32 decks)

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