Main Turbine(MT1) Flashcards
What is the purpose of the Main Turbine?
Converts the heat energy of the steam to kinetic energy and then work by rotating the turbine shaft(rotational energy)
What is the system designator for Turbine Exhaust?
TE
What is the system designator for Turbine Exhaust Hood Spary?
TS
What are the two types of turbine blades?
- Impulse Blades
2. Reaction Blades
What type of blading makes up the majority of the High Pressure and Low Pressure Turbine blading?
The HP and LP Turbines use mostly impulse blading, but there are some combination impulse/reaction blades.
What is the principle of operation for Impulse Blading?
Rotation is developed by the force of the steam impinging on the rotating blades.
What makes up a “stage” in a turbine?
A stage is a row of stationary nozzles and rotating blades.
What is the principle of operation for Impulse Blading?
Reaction blading uses the force of the steam exiting the blade to cause it to move. The low pressure turbines use some reaction blading, along with impulse blading.
What is the general flow path from the Main Steam Stop Valves to through the Low Pressure Turbine?
Equalization Header -> Stop Valves -> Steam Chest -> Control Valves -> Nozzle Blocks -> High Pressure Turbine -> MSRs -> Crossaround Pipes -> Combined Intermediate Valves -> Reheat Stop Valves -> Low Pressure Turbines.
How many High and Low Pressure Turbines are there?
1 - High Pressure Turbine
3 - Low Pressure Turbines
What does the term “Tandem” mean when describing the turbine configuration?
Tandem means that all four turbines share a common shaft.
What does the term “Compound” mean when describing the turbine configuration?
Compound means that the steam flows through HP Turbine and then the 3 LP Turbines in series.
What does the term “Double Flow” mean when describing the turbine configuration?
Double-flow means that the steam enters at the center of the turbine blading and travels towards both ends.
What are the purpose of the Slide Pads in relation to the Main Turbine?
Since the turbine components can expand and contract as the turbine is either heated or cooled down, slide pads are utilized to accommodate this expansion and contraction.
What is the design/purpose of the High Pressure Turbine?
- Single shell construction
- 4 nozzle blocks direct steam flow to the first stage blading
- Blading converts the kinetic energy of the steam into rotational work
- Extraction steam from the turbine supplies feedwater heating
- Exhausts to the Moisture Separator Reheater
What is the purpose of the Turbine Casing(Shell)?
- Confines and directs the steam
- Provides structural frame for the turbine
- Holds the stationary nozzle diaphragms so that they are sandwiched between the rotating bucket wheels without contacting the rotating parts.
- Supports the rotor
What is the purpose of the Shroud Bands?
- Support the steam buckets
- Contains the steam
- Dampen vibration
* not used on the last stage of the LP Turbine*
What is the design/purpose of the Low Pressure Turbine?
- Three parallel flow Low Pressure Turbines
- Has an inner and outer casing
- The outer casing supports the inner casing and directs exhaust steam to the main condenser
What function to does the outer casing of the Low Pressure Turbine perform at the outlet of the inner casing?
The outer casing acts as the “Exhaust Hood” at the outlet of the inner casing, directing the steam from the last stage of the LP Turbine to the condenser.
What is the purpose of the Diaphragms?
The Diaphragms are the curved passages which fit into the turbine shell and around the shaft and blades. They direct the flow of steam at the proper angle and velocity from stage to stage.
What is the purpose of the Spill Strip Seals?
- Attached to the Casings
2. Prevent steam blow-by
Where is the Front Standard and what components are contained in it?
- The Front Standard is located at the front of the High Pressure Turbine
- The Front Standard houses:
A. Mechanical Overspeed Trip Device
B. Lube Oil Gauges
C. Manual Trip Handle
D. Turbine Supervisory Instrumentation(vibration, eccentricity, shell/rotor expansion)
E. Shaft Driven Oil Pump
What is the purpose of the Turbine Stop Valves?
- Quickly shutoff steam to the main turbine in an emergency
- Act as an isolation valve between the Steam Generators and the main turbine
- Close in approximately 1/2 second
What makes up the Steam Chest?
The outlet of the Turbine Stop Valves is welded to the inlet of the Turbine Control Valves. This portion of metal located between all 4 of each valve is called the Steam Chest.