MT/ MSR Flashcards
What is the purpose of the MSR’s?
Improve the quality of the high pressure turbine exhaust steam before it enters the LPT. Improves LPT efficiency. Aids in overall plant efficiency.
How does the MSR improve the quality of the steam?
By mechanically removing moisture and reheating the dry steam by passing it across the reheater tube bundles.
What is the purpose of the MT system?
- Convert thermal energy from SG’s to mechanical energy that is used to spin the MG.
- Provide extraction steam for FW heating to increase plant efficiency.
- Provide hot reheat steam for operation of MFWPT’s.
Where does the the HPT provide extraction steam to?
3rd stage to 1st stage reheater MSR and 7 HP FW htr
5th stage to 6 HP FW htr
Where does the LPT provide extraction steam to?
8th- #4 LP FW Htr
9th- #3 LP FW Htr
11th- #2 LP FW Htr
12th- #1 LP FW Htr
What provides steam to the 2nd stage MSR reheater coils?
Main steam
What does Gland seal do for the MT system?
Prevent steam leaking out
Prevent air leaking in
What is the thrust bearing?
Located on the turbine shaft between HPT and 1st LPT. It supports axial thrust of rotors.
How many journal bearings are there>
One located at each end of all turbines and MG. 10 total
What does the MT Turning Gear do?
- Rotates shaft slowly and continually during shutdown periods when rotor temp changes occur
- To jack the rotor small amounts at desired intervals to facilitate inspection.
- Helps provide a more uniform and controlled starting sequence
Describe the starting of the TG.
Piggyback motor mounted on top of TG.
Once Start is pressed the piggyback motor will start if;
- MG C/B’s or motor operated disconnect are/is open
- Bearing lift pump is running
- Bearing LO pressure is adequate
- TG is disengaged
Where is the MT overspeed device located?
on the front standard of the main turbine
How many speed sensors are there? What are they for?
5 for EHC speed control
1 for Turbine supervisory system
What is the purpose of the MSR’s?
Designed to remove excess water, via moisture separators (chevron vanes), and raise steam temperature to super-heated steam
What is the LPT side to side differential temperature maximum difference?
50 degrees F
What are the CIV’s?
Combined intermediate valves (1-6)
Two valves in one valve body and share a common seat
What do the CIV’s prevent against?
Overspeed condition caused by the cross around piping.
What are the two valves called in a CIV?
Intercept Valve and Stop Valve
What is the purpose of the stop valve?
Serve as a backup to the IV’s to isolate flow during a loss of load in the event of a failure of the IV.
Which valves in the MT valves are controlling?
Intercept valves 1-3, Main Turbine Stop valve 2, and Control valves 1-4
Which valve in the MT system are non-controlling?
Main turbine stop valves 1,3,4, Intercept valves 4-6, Intermediate stop valves 1-6.
Explain the relationship with the controlling and non-controlling valves in the MT system?
Controlling are considered master and non-controlling are considered slave. When a controlling valve goes closed to 50% the slave valve will trip closed. When a controlling valve opens to 90% the associated slave valve will open.
After the piggyback motor for the MT TG is started; when will the TG engage?
- Rotor speed less then 2 RPM
- Low speed permissive from EHC system
