Question Set 16

Question No. 1

Which heating value is indicated by a calorimeter and why?

Answer:

Gross heating value because steam is condensed and heat of vapour formed is recovered.

Question No. 2                   

When does Emergency Seal Oil Pump automatically start?

Answer:

When its pressure switch senses Main Seal Oil Pump discharge pressure reduced to 78 PSI.

Question No. 3

What is the consequence of not maintaining hydrogen (or air) pressure in generator casing at a value above atmospheric pressure when seal oil system is in service?

Answer:

Failure to do so will cause excessive seal oil to be drawn into the generator.

Question No. 4

What is a radial-flow turbine?

Answer:

In a radial-flow turbine, steam flows outward from the shaft to the casing. The unit is usually a reaction unit, having both fixed and moving blades.

Question No. 5

What are four types of turbine seals?

Answer:

1.     Carbon rings fitted in segments around the shaft and held together by garter or retainer springs.

2.     Labyrinth mated with shaft serration’s or shaft seal strips.

3.     Water seals where a shaft runner acts as a pump to create a ring of water around the shaft. Use only treated water to avoid shaft pitting.

4.     Stuffing box using woven or soft packing rings that are compressed with a gland to prevent leakage along the shaft.

Question No. 6

What are two types of clearance in a turbine?

Answer:

Radial – clearance at the tips of the rotor and casing.

Axial – the fore-and-aft clearance, at the sides of the rotor and the casing.

Question No. 7

Which reactor uses natural uranium as fuel?

Answer:

Gas cooled reactors.

Question No. 8

Which reactor uses heavy water as moderator?

Answer: CANDU.

Question No. 9

Which reactor requires no moderator?

Answer: Breeder reactor.

Question No. 10

Which reactor uses primary coolant as fluoride salts of lithium, beryllium, thorium and uranium?

Answer: Molten salt breeder reactor.