Question Set 15

Question No. 1

What is operating pressure?

Answer:

The amount of pressure nearest the point of performing work at the output end of a pneumatic system. The system operating pressure is used to specify the capability of valves and actuators.

Question No. 2

What is the effect of inter cooling in gas turbines?

Answer:

It decreases thermal efficiency but increases net output.

Question No. 3

What are the safety valves? How many on each boiler?

Answer:

A valve opening automatically to relieve excessive pressure, especially in a boiler.

There are normally two to six safety valves provided in the drum depending upon the capacity.

The super heater outlet will have one to three safety valves on either side of the boiler. There will be an electro metric relief valve on the super heater pipe in addition. This valve will be set at lower pressure than the lowest set safety valve on the super heater. The reheater pipes both at the inlet and outlet side will also have safety valves which can range from two to eight both in the inlet and outlet of the reheater put together.

Question No. 4

What is a sentinel valve?

Answer:

Sentinel valves are simply small relief valves installed in some systems to warn of impending over pressurization. Sentinel valves do not relieve the pressure of the system. If the situation causing the sentinel valve to lift is not corrected, a relief valve (if installed) will lift to protect the system or component. If a relief valve is not installed, action must be taken quickly to secure the piece of equipment or system to reduce the pressure.

Question No. 5

In which reactor the coolant and moderator are the same?

Answer:

Pressurized water reactor.

Question No. 6

Which reactor has no moderator?

Answer:

Fast breeder reactor.

Question No. 7

What are thermal neutrons?

Answer:

Thermal neutrons are slow neutrons (having energy below 1 eV) which are in thermal equilibrium with their surroundings.

Question No. 8

What is the function of Hydrogen seals work on a generator?

Answer:

Provide a seal between the generator housings and rotor shaft to maintain the pressurized hydrogen gas inside the generator. Also, provides a trap-vent system to prevent the release of hydrogen into the turbine generator lube oil system and building atmosphere.

Question No. 9

How is the excess discharge pressure prevented?

Answer:

Pressure relief valves on the discharge side of each seal oil pump relieve back to seal oil system.

Question No. 10

Which two seal oil pumps are driven from the same motor?

Answer:

Main seal oil pump and re-circular seal oil pump; both are driven by Main seal oil pump motor.