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NLO - Systems > [ED] - Extraction Steam and Drains > Flashcards

[ED] - Extraction Steam and Drains Flashcards

1
Q

[ED]

[ED] purpose?

Extraction Steam & Drains

A

Preheats CD and FW prior to feedwater entering the S/Gs to increase plant efficiency

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2
Q

[ED]

What provides steam to #4 LP feedwater heater during startup?

Extraction Steam & Drains

A

[AS]

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3
Q

[ED]

What water system makes-up to the bottom of the ED blowdown stack?

Extraction Steam & Drains

A

[DS] Domestic Water

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4
Q

[ED]

What is the purpose of the ED blowdown stack?

Extraction Steam & Drains

A

-collection point for steam traps, HP heater relief valves and miscellaneous [AS] header drains

Aux Steam

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5
Q

[ED]

When is [DS] added to [ED] blowdown stack?
What occurs if [DS] is OOS?

(Domestic Water)

Extraction Steam & Drains

A

If temp of water >150F

Steam will come out of the blowdown stack and north Condenser sump

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6
Q

[ED]

GA-N2 & ED?

Extraction Steam & Drains

A

Supplies Nitrogen blanketing of FW Heater Shells & HDTs during long term shutdown operations

Feedwater
Heater Drain Tanks

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7
Q

[ED]

[IA] & [ED]?

2

Extraction Steam & Drains

A

[MT] control system uses [IA] in Turbine Critical and Non-Critical Relay Dump Valves (provide a signal to control BTVs)

For use all [ED] AOVs

Main Turbine
Bleeder Trip Valves
Instrument Air
Air Operated Valves
Extraction Steam & Drains

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8
Q

[ED]

How are BTV’s affected by a loss of [IA]?

Extraction Steam & Drains
Bleeder Trip Valves

A

go partially closed (Lose open permissives)

remain open due to [ED] flow

Bleeder Trip Valves
Extraction Steam

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9
Q

Where are the Heater Drain Pumps powered from?

Extraction Steam & Drains

A

‘A’ from NBN-S02

‘B’ from NBN-S01

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10
Q

[ED]

Where does seal water for each Heater Drain Pump come from?

Extraction Steam & Drains

A

Condensate Header
(375-500 psig)

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11
Q

[ED]

What positions the Heater Drain Pump mini-flow valves? When will it close? What controls the position of the heater drain pump discharge valve?

Extraction Steam & Drains

A

Heater Drain Pumps flow transmitter

as the unit comes up in power and more extraction drain flow is available

heater drain tank normal level control valve

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12
Q

[ED]

What signals stop the Heater Drain Pumps?

3

Extraction Steam & Drains

A

HDT lo-lo level alarm

Heater Drain Pump low flow after a time delay

Electrical protection signal

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13
Q

[ED]

Where are Heater Drain Pumps located?
What allows one heater drain pump operation?

Extraction Steam & Drains

A

TB 100’ (West of Main Feed Pumps)

Open suction
and vent cross-tie between HDTs

Heater Drain Tanks

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14
Q

[ED]

Why doesn’t #5 FW Heater have a level control system?

Extraction Steam & Drains

A

No drain cooler region

Drains directly to the HDT

Heater Drain Tank

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15
Q

[ED]

Which LP FW heaters have four inlets?
How many do the others have?

Extraction Steam & Drains

A

1 & 2

3 & 4 have 1 inlet each

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16
Q

Which feedwater heater has an input from S/G blowdown system?

Extraction Steam & Drains

A

3

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17
Q

[ED]

What is the purpose of the BTVs? Which feedwater heaters have BTVs?

Extraction Steam & Drains
Bleeder Trip Valves

A

Prevent [MT] reverse steam flow (overspeed) on Turbine Trip

3-7

Main Turbine

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18
Q

[ED]

What on the BTVs assists disc opening with min differential steam pressure?

Extraction Steam & Drains
Bleeder Trip Valves

A

Balance Arm device

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19
Q

What happens the Bleeder Trip Valve test valve actuates?

Extraction Steam & Drains

A

air pressure across the operator piston is equalized to allow partial closing of valve disc by spring force

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20
Q

Why are there 2 BTVs on #4 FW heater extraction line?

Extraction Steam & Drains
Feedwater

A

there is enough energy in #4 by itself to cause an overspeed trip

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21
Q

[ED]

Which level control valves are reverse acting in [ED]?

Extraction Steam & Drains

A

All high level CVs and #1 LP heater normal level CVs

Low Pressure
Control Valves

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22
Q

At what air signals are the reverse acting valves full open and full closed in the ED system?

Extraction Steam & Drains

A

Full open with 3#

Full closed with 15#

(Direct acting is the complete opposite)

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23
Q

What happens upon a hi-hi signal in a HP feedwater heaters?

Extraction Steam & Drains

A

Isolates extraction steam

Closes the normal level control valve of the preceding heater

Opens the affected heater’s motor operated extraction steam line drain valve

In addition, for the HP heaters, the 1st and 2nd stage reheater drain tank vents isolate from the affected heater and vent to the main condenser

24
Q

What happens upon a hi-hi signal in a LP feedwater heaters?

Extraction Steam & Drains

A

Isolated entire LP heater train by closing the heater train isolation valves

Isolated extraction steam to #3 and #4 heaters

Opens the extraction line solenoid operated drain valves for #3 and #4 heaters

25
Q

Below what power level may there be insufficient D/P between the heater shells to allow for proper operation of the normal level control valves in the ED system?

Extraction Steam & Drains

A

20%

high level control valves operate to keep alarms clear until power level is sufficiently raised

26
Q

When is the first heater drain pump started?

Extraction Steam & Drains

A

25% power

27
Q

When is the second heater drain pump started?

Extraction Steam & Drains

A

Between 30 and 40%

28
Q

During a plant shutdown, when are the Heater Drain Pumps secured?

Extraction Steam & Drains

A

First one at 40%, second one at 25%

29
Q

How is the ED system affected by a loss of IA?

Extraction Steam & Drains

A

Heater Drain Pump discharge valve fails closed, recirc valve fails open, putting the pump on recirc

Heater Drain Tank, MSR Drain Tank, 1st and 2nd Stage Reheater Drain tank, and Feedwater heater High Level Dump valves will all fail open and the Normal Level Control Valves fail closed (Except #1 heater)

Heater Drain pump will eventually trip on low flow or Heater Drain tank lo lo level signals

The main steam supply to the 2nd stage reheater will isolate and the 1st and 2nd stage Reheater Drain Tanks and Tube Bundles will vent to the condenser instead of their associated Feedwater heaters

30
Q

What is the purpose of the HDTs (heater drain tanks)?

Extraction Steam & Drains

A

ultimate collection point for most of the normal drains within the ED system

provides suction for the heater drain pumps

tank level regulated flow to the Main feed pumps

receives mini flow line from heater drain pump

31
Q

Where are the heater drain tanks located?

Extraction Steam & Drains

A

120’ turbine building, above the heater drain pumps

32
Q

Concerning the ED system, where do the MSR 1st stage reheater drain tanks flow to? 2nd stage reheater drain tanks?

Extraction Steam & Drains

A

6 FW heaters, then to the heater drain tank

33
Q

How many stages are the heater drain pumps?

Extraction Steam & Drains

A

5

34
Q

What is the purpose of the Feedwater heaters?

Extraction Steam & Drains

A

aid in improving the secondary system efficiency

35
Q

Concerning the High pressure feedwater heaters, what are the flow paths for the extraction steam and feedwater flow?

Extraction Steam & Drains

A

extraction steam from HP turbine comes in through the top, condenses and is drained from the bottom

feedwater flows in through the bottom, passes through the U-tubes and exits through the top

36
Q

Concerning the HP feedwater heaters, what are the differences between the #6/7 heaters and the #5 heaters?

Extraction Steam & Drains

A

6/7 have condensing and subcooling zones, has level control system, #7 drains to the #6 heater, #6 drains to the HDT

37
Q

What is the purpose of the vents on the various tanks, heat exchangers and pumps in the ED system?

Extraction Steam & Drains

A

to remove non-condensable gases and direct them to the condenser for removal

38
Q

What is the motive force of extraction steam while traveling from the turbine to the feedwater heaters?

Extraction Steam & Drains

A

the differential pressure between the turbine stages and the feedwater heater shells

39
Q

Which feedwater heaters have the supplying extraction lines cross-connected and what does the cross connect allow for?

Extraction Steam & Drains

A

3a, b, c
4a, b, c
6a, b
7a, b

allows unit operation without all high and low pressure feedwater heaters in service

40
Q

What does the High Pressure turbine provide extraction steam to?

Extraction Steam & Drains

A

3rd stage- 7A/B heaters and first stage reheating steam in the MSRs

5th stage- 6A/B heaters

cold reheat- 5A/B heaters

41
Q

Where do the heater drain pumps send their effluent?

Extraction Steam & Drains

A

to the suction of the main feedwater pumps

combines with the condensate just downstream of the feedwater heaters

42
Q

What is the difference in operation between direct acting and reverse acting level control valves in the feedwater heater level control system?

Extraction Steam & Drains

A

direct acting- higher air pressure opens the valve

reverse acting- higher air pressure closes the valve

43
Q

Where do the MSR drain tanks vent to? Where does the heater drain pump vent its suction line to?

Extraction Steam & Drains

A

their respective MSR/Hot reheat line

respective heater drain tank

44
Q

Where do the first stage reheater drain tanks normally vent to?

Extraction Steam & Drains

A

A and C vent to #6A heater extraction line

B and D vent to #6B heater extraction line

all four vent back to their respective 1st stage reheater tube bundle outlet for steam scavenging

(on high level, vent to the condenser)

45
Q

Where do the 2nd stage reheater drain tanks normally vent to?

Extraction Steam & Drains

A

A and C vent to #7A heater extraction line

B and D vent to #7B heater extraction line

all four vent back to their respective 2nd stage reheater tube bundle outlet for steam scavenging

(on high level, vent to the condenser)

46
Q

Where do the heater drain tanks vent to?

Extraction Steam & Drains

A

to their respective #5 FW heater

both tanks also have a vapor cross-connect line to each other

47
Q

Where do the #5, 6 and 7 feedwater heaters vent to?

Extraction Steam & Drains

A

both trains all tie in together to a common header and vent to the condenser

48
Q

How does the ED system interface with the SC (secondary chemical control) system?

Extraction Steam & Drains

A

Blowdown Flash Tank (BFT) vents to both of the Heater Drain Tanks by way of the vapor cross tie line between the HDT’s.

The blowdown flow from the Blowdown Flash Tank can be directed to the shell side of the #3 LP Heaters.

Cooling water from the blowdown heat exchanger is returned to the discharge of the heater drain pumps, which is then directed to the main feedwater pump suction.

49
Q

How does ED interface with GS?

Extraction Steam & Drains

A

LP turbine 9th stage extraction supplies sealing steam to GS on power ascension

50
Q

In the ED system, what is powered by NH?

Extraction Steam & Drains

A

MOVs, HP heater extraction steam block and drain valves, heater drain pump motor space heaters

51
Q

In the ED system, what is powered by NK?

Extraction Steam & Drains

A

solenoids, controls, indication and alarms for various valves

52
Q

In the ED system, What is powered by NN?

Extraction Steam & Drains

A

LP FW heater steam pressure instrumentation

HTR DRN pump discharge/suction D/P, tank level and pump flow instrumentation

53
Q

What cools the HTR DRN pump lube oil coolers?

Extraction Steam & Drains

A

turbine cooling water

54
Q

What maintains water level in the LP feedwater heater drain cooler, or subcooling zone?

Extraction Steam & Drains

A

normal level control valve

55
Q

What is the purpose of having reverse acting normal and high level control valves in the ED system?

Extraction Steam & Drains

A

to ensure that on a loss of IA, the ED system will drain its contents to the main condenser

56
Q

Describe the new level control valves for the LP feedwater heaters.

Extraction Steam & Drains

A

Vee style ball valve, provides beter throttling and seal off flow

can be positioned in either fail open or fail closed designation with the same valve mounting configuration, causing less installation errors

rotory positioners with rotary actuators with a lever

4 gauges instead of three

smaller in size

57
Q

What is the sequence for putting the MSR and 1st/2nd stage drain tanks in service to their normal level control valves?

Extraction Steam & Drains

A

At 10% turbine power, 1st stage and MSR drain tanks go to normal level control valves, leading to the #6 FW heaters (1st stage) and the HTR DRN tank (MSR drain tank)

At 20% turbine power, 2nd stage drain tank goes to normal level control valve, leading to #7 FW heaters

NLO - Systems (70 decks)

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