Extraction Stea & Drains(ED)

Question 1

What does the Heater Drain Tank provide for the Extraction Steam system ?

Answer 1

-Ultimate drain point for most of the normal drains in ED system
-Provides suction source for the HTR Drain Pumps

Question 2

Where does the HTR Drain Pumps discharge to ?

Answer 2

-Discharges to suction of the associated Main FW Pump

Question 3

How is flow regulated to the Main FW Pump suction ?

Answer 3

-Regulated by HTR Drain Tank level to ensure it has enough water for HTR Drain Pump
-Mini flow back to HTR Drain Tank is provided for each HTR Drain Pump

Question 4

How many HTR Drain Pumps are there? Where do they take suction from ?

Answer 4

There are two HTR Drain Pumps, that have there own HTR Drain Tank to take suction from

Question 5

What powers the HTR Drain Pumps ?

Answer 5

-NBN-S01 powers ‘B’ HTR Drain Pump
-NBN-S02 powers ‘A’ HTR Drain Pump
THINK OPPOSITE

Question 6

Where is seal water provided from for HTR Drain Pumps ?

Answer 6

Provided from Condensate Header at 375-500psig

Question 7

Where is cooling water for the HTR Drain Pumps stuffing box provide from ?

Answer 7

Provided from condensate service header at 50-100psig

Question 8

What is the HTR Drain Pump mini follow valve positioned by ?

Answer 8

Positioned by HTR Drain Pump flow transmitter to maintain minimum flow through HTR Drain Pump

Question 9

What happens to the HTR Drain Pump mini flow valve when unit comes up in power & has more extraction steam flow available to pump ?

Answer 9

Mini flow valve will close

Question 10

When will stop the HTR Drain Pumps ?

Answer 10

-HTR Drain Tank LO-LO level alarm
-HTR Drain Pump low flow after time delay
-Electrical protection

Question 11

Where does flow from the HTR Drain Tank go when the High Level Control Valve actuates ?

Answer 11

Directs high energy fluid to condenser

Question 12

Why is it bad for flow from the HTR Drain Tank High Level Control Valves to actuate ?

Answer 12

It’s bad on the tube because it causes high vibration & erosion in tube bundle due to velocity & thermal changes when entering condenser

Question 13

What just be done to minimize high level control valve to be activated ?

Answer 13

Reducing power to 50% until HTR Drain Trains are cross-tied

Question 14

Why is having a cross connected HTR Drain Pump important , when a High Level Control Valve actuates ?

Answer 14

Reduce HTR Drain Tanks High Level Control Valve actuation <25%

Question 15

How many HP Feedwater Heaters trains are there ?

Answer 15

-There are two parallel trains of HPFWH

Question 16

Why does the #5 HPFWH not have a level control system ?

Answer 16

It doesn’t contain a drain cooler region

Question 17

Where does the #5 HPFWH directly drain too ?

Answer 17

Drains to HTR Drain Tank

Question 18

How many trains of LPFWH are there ?

Answer 18

There are three LPFWH trains in parallel

Question 19

What stages of the LP Turbine do the LPFWH receive extraction steam from ?

Answer 19

Receives extraction steam from stages 8,9,11,12

Question 20

How is the LPFWH sub cooling zone or drain cooler water level maintained ?

Answer 20

Maintained by Normal Level Control Valve

Question 21

What’re the bleeder trip valves used for ?

Answer 21

-Used during turbine trip to prevent overspeed on a turbine trip

Question 22

How do the bleeder trip valves work ?

Answer 22

-Closes automatically when steam flow stops or has reverse flow during turbine trip
-Has pneumatic cylinders that uses spring force to help close valve when air is bled off

Question 23

What is the balance arm device used for on the bleeder trip valves ?

Answer 23

It helps open valve with minimum differential steam pressure

Question 24

Why does the bleeder trip valve pneumatic Cylindrical device equipped with three-way test valve ?

Answer 24

-Equalizes air pressure across operator cylinder to partial close valve by the spring force
-This will cause DP to go up across valve which shows the valve isn’t stuck open

Question 25

Why does the #4 LPFWH have two Bleeder Trip Valves on its extraction steam lines ?

Answer 25

Has enough energy to cause overspeed trip by itself

Question 26

Which valves in the ED system are reverse acting ?

Answer 26

-All the High Level Control Valves AND #1 LPFWH NORMAL level control valve are Reverse-Acting

Question 27

Which valves in the ED system are direct acting ?

Answer 27

-2-7 LPFWH normal level control valves -1st & 2nd stage reheated drain tanks normal level control valves

Question 28

Where does the ED system drain to on a loss of instrument air ?

Answer 28

Will drain to the Main Condenser

Question 29

How does the heaters normal or high level control valves operate ?

Answer 29

They operate water level within pipe stack that will send out output air signal to valve position

Question 30

What’s the procedure categories for placing a sight glass in/out of service ?

Answer 30

-1st &2nd Stage Reheater Drain Tanks -Moisture Separator Drain Tank -Fw Heater -HTR Drain Tank

Question 31

What automatically happens to HPFWH during a HI-HI level ?

Answer 31

-Isolates extraction steam supply valve -Closes normal control valve -Open extraction steam line drain valve to condenser -1st&2nd Reheater Drain Tank vent line will isolate from the affected heater

Question 32

What will automatically happen during a LPFWH HI-HI Level ?

Answer 32

-Entire LP train will be isolated by heater drain isolation valves -Isolates extraction steam to #3 & #4 heaters -Opens extraction line solenoid operated drain valve for #3 & #4 heaters

Question 33

Which level control valves are used during low power operations for the LP & HP Heaters ?

Answer 33

High level control valves will open because insufficient DP

Question 34

When coming up in power how long are the Moisture Separator Drain Tank & First Stage Reheater Drain Tank directing flow to Main Condenser ?

Answer 34

Until Turbine Generator 10% loaded

Question 35

What happens to Moisture separator Drain Tank & 1st stage Reheater drain Tank when turbine load reaches 10%?

Answer 35

-High Level Control valves will close -Normal Level Control valves will OPEN

Question 36

What happens to 2nd Stage Reheater Drain Tank when turbine load reaches 20% ?

Answer 36

-High level control valve goes closed -Normal Level Control Valve goes open

Question 37

When are the HTR Drain Pumps starting when coming up in power ?

Answer 37

-When power reaches 25% the first HTR Drain Pump starts preferable on same side as FW Pump -2nd HTR Drain Pump can be started 30-40%

Question 38

When do the HTR Drain Pumps stop ?

Answer 38

-1st HTR Drain Pump will stop at 40% -2nd HTR Drain Pump will stop at 25%

Question 39

If power operation with only one HTR Drain Pump why just precautions be taken ?

Answer 39

Must be taken to limit vibration & erosion in condenser tube bundle due to high energy fluid to condenser

Question 40

What happens to HTR Drain Pumps Discharge Valve on loss of Instrument Air ?

Answer 40

Discharge valve will fail closed & Recirc valve will fail open -Putting pump in full Recirculation