Question No. 1

How would you stop air from leaking into a condenser?

Answer:

First, find the leak by passing a flame over the suspected part while the condenser is under vacuum. Leaks in the flange joints or porous castings can be stopped with asphalt paint or shellac. Tallow or heavy grease will stop leaks around the valve stems. Small leaks around the porous castings, flange nuts, or valve stems can always be found by the flame test. So, you might have to put the condenser under a few pounds of air pressure and apply soapsuds to the suspected trouble parts.

Question No. 2

In how many patterns are tie wires used?

Answer:

1.     In one design, tie wire is passed through the blade vane.

1.     In another design, an integral stub is joined by welding/brazing.

Question No. 3

In steam turbines, is there any alternative to the shrunk-on-disc design?

Answer:

Two designs are available at present:

1.     Welded rotor in which each individual disc is welded, instead of shrunk, onto the main shaft.

2.     Mono-bloc rotor in which the entire shaft and blade assembly is manufactured from a single forging.

Question No. 4

In which case does upgrading imply life extension of steam turbines?

Answer:

For a capital-short electric utility plant, upgrading comes to mean extending the life of that plant scheduled for retirement.

Question No. 5

In which cases does erosion corrosion damage appear?

Answer: It is commonly encountered in nuclear steam turbines and old fossil-fuel-fired units that employ lower steam temperatures and pressures.

Question No. 6

In which cases does upgrading mean up-rating the turbine capacity?

Answer:

For an electric utility system facing uncertain load growth, upgrading is chiefly up rating.

It is an inexpensive way to add capacity in small increments.

Question No. 7

In which part of the steam turbine does corrosion fatigue occur?

Answer:

In the wet stages of the LP cylinder.

Question No. 8

In which part of the steam turbine does stress corrosion cracking (SCC) occur?

Answer:

In the wet stages of the low-pressure turbine.

Question No. 9

What are the basic causes of the problems are?

Answer:

1.     Normal wear.

2.     Fatigue failure due to high stress.

3.     Design deficiency.

4.     Aggressive operating environment

Question No. 10

In which turbine is this pressure compounding used?

Answer:

In the Rateau turbine.