Purpose Of…

Question 1

Purpose of:
Hydrogen

Answer 1

Cool the generator rotor

Question 2

Purpose of:
Seal Oil

Answer 2

Contain Hydrogen in the Generator and prevent it leaking out at rotor

Question 3

Purpose of:
EHC

Answer 3

ElectroHydraulic Control Oil
Oil at 2400psi to hold open Main Stream stop valves, Turbine control valves and ReHeat intercept valves.

Question 4

Purpose of:
Main Lube Oil

Answer 4

Provide oil flow to cool and lubricate turbine and generator bearings.
Return oil to H2 seal oil tank.

Question 5

Purpose of:
Turbine

Answer 5

Convert thermal energy of the steam to mechanical energy as torque on the shaft

Question 6

Purpose of:
Generator

Answer 6

Convert mechanical energy of the turbine to electric energy at 23,000V

Question 7

Purpose of:
Main transformer

Answer 7

Step up generator voltage from 23kV to 515kV for transmission on the grid
OR
Step down grid voltage to supply the auxiliary transformers

Question 8

Purpose of:
Auxiliary transformers

Answer 8

Take 23kV input and step it down to 13.8kV and 4160V for use on the plant site

Question 9

Purpose of:
Turning gear

Answer 9

Keeps turbine turning at 5 rpm when not in service to prevent bowing of hot shaft during first few days after shutdown.

Question 10

Purpose of:
Circulating Water

Answer 10

Provides water at ~90F to 3 loads:
-Condensing turbine exhaust steam
-Closed Cycle cooling heat exchangers
-Vacuum pump seal water cooling

Question 11

Purpose of:
Closed Cycle cooling water

Answer 11

Circulate water at 100F to cool equipment in the plant.

Question 12

Purpose of:
Stator cooling water

Answer 12

Circulates very pure water through the generator stator bars for cooling

Question 13

Purpose of:
FD Fan

Answer 13

Provide air pressure to:
- deliver oxygen to burners to support combustion
-overfire air to “hold down” the fire ball and reduce NOx
-dilution air for transporting anhydrous ammonia into flue gas

Question 14

Purpose of:
Mill (Pulverizer)

Answer 14

Grind coal into fine powder to supply burners

Question 15

Purpose of:
Slakers

Answer 15

Dissolve pebble lime into slurry to maintain level in slurry tank

Question 16

Purpose of:
Aqueous Ammonia
NH3(aq)

Answer 16

Added to Condensate system to raise pH in the steam cycle

Question 17

Purpose of:
Anhydrous Ammonia
NH3(g)

Answer 17

Sprayed into flue gas upstream of the SCR (Selective Catalytic Reducer) to remove NOx
NH3 + NO3 ➡️ N2 + H2O

Question 18

Purpose of:
Activated Carbon

Answer 18

Absorbs Mercury (Hg) out of the flue gas and traps it in the fly ash

Question 19

Purpose of:
Feedwater

Answer 19

Provides high pressure water to:
-maintain drum level
-cool (attemporate) main stream
-cool (attemporate) ReHeat steam

Question 20

Purpose of:
Condenser

Answer 20

Removes heat from turbine exhaust steam and converts it to water for return to the boiler

Question 21

Purpose of:
Vacuum pumps

Answer 21

Remove non-condensable gasses (air) from the condenser.

Question 22

Purpose of:
Boiler

Answer 22

Convert chemical energy of the fuel to thermal energy of the steam by boiling water to provide high pressure superheated steam to the turbine.

At full load steam will be 2520psi and 1050F

Question 23

Purpose of:
Backpass Dampers

Answer 23

Control Hot ReHeat temperature by balancing flue gas flow across the Primary Superheat section and the ReHeat section of the boiler backpass.

Question 24

Purpose of:
Feedwater Heaters

Answer 24

Take extraction steam from the turbine to preheat Feedwater before entering the boiler to improve efficiency.

Question 25

Purpose of:
Rotary Air Heater
(RAH)

Answer 25

Transfer heat from the flue gas to Primary Air and Secondary Air

Question 26

Purpose of:
Steam Preheat Coils

Answer 26

Heats PA and FD air before entering the RAH to raise cold end metal temperature and prevent condensation inside the flue gas duct work.

Question 27

Purpose of:
Baghouse

Answer 27

Removes particulate (fly ash) from the flue gas
Provides a place for Carbon to accumulate to filter Mercury from the flue gas.

Question 28

Purpose of:
Seal steam

Answer 28

To prevent air in-leakage at the shaft of the LP turbine (and the HP and IP turbines during startup)

Question 29

Purpose of:
Gland steam exhaust condenser

Answer 29

To capture leak off from the turbine seal steam so it doesn’t fill the turbine deck

Question 30

Purpose of:
Atomizer

Answer 30

Distributes slurry and dilution water into a fine mist to maximize surface area for better chemical reaction and heat transfer.
Uses nozzles spinning on the disc at 11,000 rpm

Question 31

Purpose of:
DA
(Deaerator)

Answer 31

Removes dissolved oxygen from condensate
Provides NPSH for Boiler Feed Pumps

Question 32

Purpose of:
Acid

Answer 32

Adds H+ ions
Lowers pH
Regenerates Cation resin.

Question 33

Purpose of:
Caustic

Answer 33

Adds OH- ions
Raises pH
Regenerates Anion resin

*Caustic crystallizes at low temperatures, which is why the containment is heated in winter and the water heater treats it before use in regens.

Question 34

Purpose of:
Sodium Hypochlorite

Answer 34

Commonly called “Hypo” and chemically identical to laundry bleach.
Used to kill biologicals.
Injected in Riverwater and Clarifiers to prevent algae in the Cooling Tower.

Question 35

Purpose of:
Lime Slurry

Answer 35

Distributed in the flue gas to absorb SO2.

Question 36

Purpose of:
Dilution Water

Answer 36

Control SDA outlet temperature.
Higher dilution water flow increases the surface area for the slurry/SO2 reaction, improving the efficiency of the slurry.