Steam Turbines

Front 1

Back 1

Cross Compound

Front 2

Back 2

Tandem Compound

Front 3

Back 3

Throttle Trip Valve

Front 4

Steam Turbines convert...

Back 4

Heat and pressure energy to mechanical energy.

Front 5

% Efficiency of Steam Turbine

Back 5

40%

Front 6

Basic parts of turbine

Back 6

Rotor, blades and nozzles

Front 7

Steam flow thru turbine

Back 7

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.

Front 8

Types of turbines

Back 8

Condensing

non-condensing

extraction

mixed pressure

topping

Cross Compound

Tandem Compound

Front 9

Condensing Turbine

Back 9

Steam exhausts to condenser where steam condensed by cooling water. Condensate returns to boiler as feedwater.

Front 10

Non-condensing (Backpressure) Turbine

Back 10

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.

Front 11

Extraction turbines

Back 11

Extract steam for feedwater heating or process heat

Front 12

Mixed pressure turbines

Back 12

Induction turbine. Excess process steam applied to low pressure sections of turbine

Front 13

Topping turbines

Back 13

Exhaust steam used for mechanical drive or electrical power generation.

Front 14

Cross Compound turbines

Back 14

Large turbines with a generator on each side of 2 shafts running at dif speeds.

Front 15

Tandem Compound turbines

Back 15

Large. Coupled together on a single shafts and applied to one generator

Front 16

Thrust in low pressure compound turbines

Back 16

Happens due to pressure drop across each row of moving blades.

Front 17

Thrust elimination in compound turbines

Back 17

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.

Front 18

Turning gear

Back 18

Electric motor turns turbine shaft at 20-40 rpm to prevent shaft from warping from uneven cooling when turbine is shut down.

Front 19

Emergency stop valve

Back 19

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.

Front 20

Governor

Back 20

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.

Front 21

Flyball governor

Back 21

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.

Front 22

Mechanical- hydraulic governor

Back 22

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.

Front 23

Back 23

Governor valves

Front 24

Back 24

Mechanical over speed trip mechanism

Front 25

Mechanical over speed trip mechanism

Back 25

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

Front 26

Shaft seal

Back 26

Prevents steam leakage around the shaft.

Prevents air leakage into casing in LP sections.

Front 27

Labyrinth seals

Back 27

Drum that turns with shaft and is grooved on the outside. Drum turns inside stationary cylinder that is grooved on the inside.

Front 28

Back 28

Labyrinth seals

Front 29

Steam in labyrinth seal

Back 29

Steam is injected in to LP turbine to keep air out. Excess goes to a heat exchanger "gland steam condenser" via gland leak off.

Front 30

Gland steam condenser

Back 30

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.

Front 31

Submersion System

Back 31

A ring that floats on the shaft rotates and carries oil from small reservoir below the bearing with oil.

Front 32

Forced lubrication

Back 32

Oil from pump provides oil to bearings. Delivers oil from central reservoir.

Front 33

3 lube oil pumps

Back 33

Main oil pump.

Auxiliary oil pump.

Emergency oil pump.

Front 34

Main oil pump.

Back 34

On shaft of turbine. Powered by rotation of shaft. Delivers oil at normal speed.

Front 35

Auxiliary oil pump

Back 35

Motor driven.

Back up if main pump doesn't deliver proper pressure and volume.

Starts automatically when oil pressure drops below a set point.

Front 36

Emergency oil pump

Back 36

Small pump driven by battery and used when electric lost. Used for hour needed for roll down.