Extraction Stea & Drains(ED) Flashcards
What does the Heater Drain Tank provide for the Extraction Steam system ?
-Ultimate drain point for most of the normal drains in ED system
-Provides suction source for the HTR Drain Pumps
Where does the HTR Drain Pumps discharge to ?
-Discharges to suction of the associated Main FW Pump
How is flow regulated to the Main FW Pump suction ?
-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
How many HTR Drain Pumps are there? Where do they take suction from ?
There are two HTR Drain Pumps, that have there own HTR Drain Tank to take suction from
What powers the HTR Drain Pumps ?
-NBN-S01 powers ‘B’ HTR Drain Pump
-NBN-S02 powers ‘A’ HTR Drain Pump
THINK OPPOSITE
Where is seal water provided from for HTR Drain Pumps ?
Provided from Condensate Header at 375-500psig
Where is cooling water for the HTR Drain Pumps stuffing box provide from ?
Provided from condensate service header at 50-100psig
What is the HTR Drain Pump mini follow valve positioned by ?
Positioned by HTR Drain Pump flow transmitter to maintain minimum flow through HTR Drain Pump
What happens to the HTR Drain Pump mini flow valve when unit comes up in power & has more extraction steam flow available to pump ?
Mini flow valve will close
When will stop the HTR Drain Pumps ?
-HTR Drain Tank LO-LO level alarm
-HTR Drain Pump low flow after time delay
-Electrical protection
Where does flow from the HTR Drain Tank go when the High Level Control Valve actuates ?
Directs high energy fluid to condenser
Why is it bad for flow from the HTR Drain Tank High Level Control Valves to actuate ?
It’s bad on the tube because it causes high vibration & erosion in tube bundle due to velocity & thermal changes when entering condenser
What just be done to minimize high level control valve to be activated ?
Reducing power to 50% until HTR Drain Trains are cross-tied
Why is having a cross connected HTR Drain Pump important , when a High Level Control Valve actuates ?
Reduce HTR Drain Tanks High Level Control Valve actuation <25%
How many HP Feedwater Heaters trains are there ?
-There are two parallel trains of HPFWH
Why does the #5 HPFWH not have a level control system ?
It doesn’t contain a drain cooler region
Where does the #5 HPFWH directly drain too ?
Drains to HTR Drain Tank
How many trains of LPFWH are there ?
There are three LPFWH trains in parallel
What stages of the LP Turbine do the LPFWH receive extraction steam from ?
Receives extraction steam from stages 8,9,11,12
How is the LPFWH sub cooling zone or drain cooler water level maintained ?
Maintained by Normal Level Control Valve
What’re the bleeder trip valves used for ?
-Used during turbine trip to prevent overspeed on a turbine trip
How do the bleeder trip valves work ?
-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
What is the balance arm device used for on the bleeder trip valves ?
It helps open valve with minimum differential steam pressure
Why does the bleeder trip valve pneumatic Cylindrical device equipped with three-way test valve ?
-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
Why does the #4 LPFWH have two Bleeder Trip Valves on its extraction steam lines ?
Has enough energy to cause overspeed trip by itself
Which valves in the ED system are reverse acting ?
-All the High Level Control Valves AND #1 LPFWH NORMAL level control valve are Reverse-Acting
Which valves in the ED system are direct acting ?
-2-7 LPFWH normal level control valves
-1st & 2nd stage reheated drain tanks normal level control valves
Where does the ED system drain to on a loss of instrument air ?
Will drain to the Main Condenser
How does the heaters normal or high level control valves operate ?
They operate water level within pipe stack that will send out output air signal to valve position
What’s the procedure categories for placing a sight glass in/out of service ?
-1st &2nd Stage Reheater Drain Tanks
-Moisture Separator Drain Tank
-Fw Heater
-HTR Drain Tank
What automatically happens to HPFWH during a HI-HI level ?
-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
What will automatically happen during a LPFWH HI-HI Level ?
-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
Which level control valves are used during low power operations for the LP & HP Heaters ?
High level control valves will open because insufficient DP
When coming up in power how long are the Moisture Separator Drain Tank & First Stage Reheater Drain Tank directing flow to Main Condenser ?
Until Turbine Generator 10% loaded
What happens to Moisture separator Drain Tank & 1st stage Reheater drain Tank when turbine load reaches 10%?
-High Level Control valves will close
-Normal Level Control valves will OPEN
What happens to 2nd Stage Reheater Drain Tank when turbine load reaches 20% ?
-High level control valve goes closed
-Normal Level Control Valve goes open
When are the HTR Drain Pumps starting when coming up in power ?
-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%
When do the HTR Drain Pumps stop ?
-1st HTR Drain Pump will stop at 40%
-2nd HTR Drain Pump will stop at 25%
If power operation with only one HTR Drain Pump why just precautions be taken ?
Must be taken to limit vibration & erosion in condenser tube bundle due to high energy fluid to condenser
What happens to HTR Drain Pumps Discharge Valve on loss of Instrument Air ?
Discharge valve will fail closed & Recirc valve will fail open
-Putting pump in full Recirculation
