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36 Cards in this Set
- Front
- Back
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Cross Compound |
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Tandem Compound |
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Throttle Trip Valve |
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Steam Turbines convert... |
Heat and pressure energy to mechanical energy. |
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% Efficiency of Steam Turbine |
40% |
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Basic parts of turbine |
Rotor, blades and nozzles |
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Steam flow thru turbine |
Steam passes thru successive rows of stationary and moving blades to spin turbine. Stationary blades direct flow of steam to next row of moving blades. |
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Types of turbines |
Condensing non-condensing extraction mixed pressure topping Cross Compound Tandem Compound |
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Condensing Turbine |
Steam exhausts to condenser where steam condensed by cooling water. Condensate returns to boiler as feedwater. |
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Non-condensing (Backpressure) Turbine |
Used when exhaust steam can be used for some sort of work as a process or heating. Acts as a pressure reducer between boiler and process steam header. |
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Extraction turbines |
Extract steam for feedwater heating or process heat |
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Mixed pressure turbines |
Induction turbine. Excess process steam applied to low pressure sections of turbine |
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Topping turbines |
Exhaust steam used for mechanical drive or electrical power generation. |
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Cross Compound turbines |
Large turbines with a generator on each side of 2 shafts running at dif speeds. |
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Tandem Compound turbines |
Large. Coupled together on a single shafts and applied to one generator |
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Thrust in low pressure compound turbines |
Happens due to pressure drop across each row of moving blades. |
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Thrust elimination in compound turbines |
Steam is admitted midway along the turbine casing and flows in both directions along successively larger rows of blades. Thrust exerted from rows of blades counteract each other. |
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Turning gear |
Electric motor turns turbine shaft at 20-40 rpm to prevent shaft from warping from uneven cooling when turbine is shut down. |
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Emergency stop valve |
Located at main steam line to entrance of high pressure turbine. Controls flow of steam in to turbine during start up. When turbine is on line, primary function of valve is to stop flow of steam in emergency situation. |
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Governor |
Controls steam flow to turbine to maintain constant speed with varying loads or hold pressure with varying steam demands. On condensing Turbine, controls inlet steam to maintain constant speed. On Backpressure turbine, maintain a constant exhaust pressure. |
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Flyball governor |
Uses centrifugal force on a set of fly balls connected to a shaft to reduce steam inlet valve as flyball speed increases and increase steam inlet valve as flyball speed decreases. |
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Mechanical- hydraulic governor |
Operated by combo of oil pressure and spring force. Superior control over mechanical governor. If oil pressure of valve is increased, the valve opens against spring tension. If oil pressure is reduced, the spring forces the valve in the closed direction. |
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Governor valves |
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Mechanical over speed trip mechanism |
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Mechanical over speed trip mechanism |
Prevents steam from entering turbine if turbine overspeeds. Weighted bolt held by spring in a channel drilled in to shaft. Set at 10% above normal operating speed |
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Shaft seal |
Prevents steam leakage around the shaft. Prevents air leakage into casing in LP sections. |
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Labyrinth seals |
Drum that turns with shaft and is grooved on the outside. Drum turns inside stationary cylinder that is grooved on the inside. |
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Labyrinth seals |
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Steam in labyrinth seal |
Steam is injected in to LP turbine to keep air out. Excess goes to a heat exchanger "gland steam condenser" via gland leak off. |
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Gland steam condenser |
Where leaking steam from labyrinth seal is condensed and sent to hot well. Draws steam from shaft area. Condensate from hot well is used to condensate steam leakoff. |
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Submersion System |
A ring that floats on the shaft rotates and carries oil from small reservoir below the bearing with oil. |
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Forced lubrication |
Oil from pump provides oil to bearings. Delivers oil from central reservoir. |
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3 lube oil pumps |
Main oil pump. Auxiliary oil pump. Emergency oil pump. |
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Main oil pump. |
On shaft of turbine. Powered by rotation of shaft. Delivers oil at normal speed. |
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Auxiliary oil pump |
Motor driven. Back up if main pump doesn't deliver proper pressure and volume. Starts automatically when oil pressure drops below a set point. |
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Emergency oil pump |
Small pump driven by battery and used when electric lost. Used for hour needed for roll down. |