Moisture Separator Reheater

Question 1

What does the MSR system do?

Answer 1

improves the quality of steam leaving the HP turbine before it enters the LP turbine by removing moisture and reheating the dried steam.

Question 2

Why are we concerned about the quality of steam entering the LP turbine?

Answer 2

Drier steam minimizes erosion of the LP turbine buckets and maximizes the efficiency of the LP turbine.

Question 3

How does cold re-heate enter the MSR?

Answer 3

via two inlet nozzles on the bottom and it exits as hot reheat via two exit nozzles out the top

Question 4

Where does the moisture that is removed from the cold reheat drain to?

Answer 4

the MSR drain tank

Question 5

What supplies the first and second stage of the MSR tube bundles?

Answer 5

First stage - 3rd stage extraction steam from the HP turbine

2nd stage - Main Steam

Question 6

Can the MSR be operated without Main steam?

Answer 6

Yes, but they won’t be as efficient. (1155MW)

Question 7

What does IA supply in the MSR system?

Answer 7

motive force for low load valve operation and drain tank level control valves

Question 8

What is extraction steam from the HP turbine used to heat?

Answer 8

5th, 6th, and 7th feedwater heater stages and the 3rd stage extraction supplies the MSR first stage reheater.

Question 9

What is the extraction steam taken from the LP turbine used to heat?

Answer 9

1-4 feedwater heaters

Question 10

At what level in the MSR drain tank will the turbine trip?

Answer 10

when level has backed all the way up to within 3” of the MSR vessel, 3 level switches will trip the turbine

Question 11

Where does the MSR drain tank drain to?

Answer 11

Normally, the associated train heater drain tank.

high level dump valve sends moisture to the condenser.

Question 12

When is the MSR high level dump valve failed open?

Answer 12

turbine power <10% and shell warming is not in progress.

Question 13

How does the MSR drain tank normal level control valve fail on a loss of IA?

Answer 13

closed and the high level dump valve opens.

a HI HI level will also fail the normal level control valve closed.

Question 14

What is scavenging steam?

Answer 14

steam that comes out of the vent on the first stage drain tank that is vented back to the first stage tube bundle outlet and to the 6th stage feedwater heater. The scavenging steam is necessary to ensure water drainage from the reheater tube bundle.

Question 15

What valves work together to regulate steam pressure in accordance with MSR and LP turbine operational limitations?

Answer 15

The pneumatically operated Reheat Steam Low load valve (RSLLV) and the motor operated RSHLV (high Load).

Question 16

What interlocks are in place to keep the Reheat Steam Source Valves from opening?

Answer 16

Reheater stop check valve must be open (keeps the 2nd stage from being put in service without the first stage in service)
Valves can’t be opened below 10% turbine load at inlet to LP turbine A.

Question 17

When is the 2nd stage drain tank high level dump valve failed open?

Answer 17

turbine power <20%

Question 18

Where is the 2nd stage drain tank vented to during purge operations?

Answer 18

the condenser.

Question 19

What is the purpose of steam scavenging?

Answer 19

prevent condensate collection in the tubes of the MSR.

Question 20

When is air purging of the MSR performed?

Answer 20

prior to placing it in service to place the bundles at condenser vacuum and to ensure uniform heating as the bundles pressurize

Question 21

What temperature is blanketing steam controlled at?

Answer 21

approx. 300F. to minimize corrosion while shutdown

Question 22

How is leak detection performed?

Answer 22

by trending steam flow rate through the 1st and 2nd stage tube bundles. deviations of more than 10% from previous reference data indicate a leak

Question 23

What is main turbine output limited to when both stages of reheat are isolated?

Answer 23

1155 MW

Question 24

Where do the MSR relief valves relieve to?

Answer 24

out the side of the turbine building.