Chapter 71- Gas Turbines

Question 1

The three things a gas turbine is considered

Answer 1

*constant flow rotors engine * heat engine * prime mover

Question 2

List two facts about early gas turbines

Answer 2

* handicapped by lack of metal that withstand high temps * air compressor and turbine had very love efficiency

Question 3

____ of the power is used for the air compression on a gas turbine

Answer 3

2/3

Question 4

Output power or ____ depends in _____

Answer 4

Power rating Mass of hot gas

Question 5

Output increases in a gas turbine when using

Answer 5

Air of maximum density

Question 6

An example of aero turbine

Answer 6

Jet engine

Question 7

An open system gas turbine

Answer 7

Air drawn from atmosphere and returned

Question 8

Air and hot gas are _____ from compressor to turbine

Answer 8

Ducted

Question 9

Turbine has to be brought up to ___% speed before the fuel is turned on

Answer 9

20-30

Question 10

The two types of gas turbine

Answer 10

Aero derivative Land based

Question 11

A simple turbine system has no (3)

Answer 11

*heat exchanger *regenerator *intercooler

Question 12

A single shaft gas turbine

Answer 12

Has only one shaft. Compressor and turbine are coupled together

Question 13

What is the majority of gas turbines in industry

Answer 13

Simple Open single shaft

Question 14

Five advantages of the gas turbine

Answer 14

*higher power to weight ratio *low installed coat *low maintenance and operating cost *minimum cooling water *rapid start up and loading

Question 15

List four disadvantages of gas turbines

Answer 15

*low mechanical and thermal efficiency *high noise level *limited types of fuel *NOx emissions

Question 16

Compared to a steam plant and gas turbine is

Answer 16

Smaller and lighter

Question 17

Absence of reciprocating motion and min wear of moving parts results in

Answer 17

Low maintenance and operating cost

Question 18

Gas turbines require Minimal cooling water and is ideal for

Answer 18

Areas where water is scarce

Question 19

What type of fuel does a turbine use

Answer 19

Clean liquid or gaseous fuels

Question 20

What’s the purpose of regenerators

Answer 20

Improve efficiency by recovering heat

Question 21

Regenerators are more efficient with

Answer 21

Cold air

Question 22

Heat recovered from exhaust gas

Answer 22

Reduces fuel quality

Question 23

What are two main benefits from combining a gas turbine with a steam plant

Answer 23

*plant economy improves * reduction in boiler size

Question 24

Gas turbines combined with steam plants are referred to as

Answer 24

Combine cycles

Question 25

What are the two things that are important for an operator to understand about gas turbines

Answer 25

How the ambient temp and atmospheric pressure effects it

Question 26

Atmospheric pressure affects _______ in a gas turbine

Answer 26

Internal combustion engine and boiler performance

Question 27

Air temperature changes

Answer 27

Air density

Question 28

Define manual start up

Answer 28

Operator starts all auxiliary systems and takes gas turbine to minimum governor setting

Question 29

Define semi automatic start ups

Answer 29

Only auxiliary system and automatic control takes gas turbine to minimum governor setting

Question 30

Define automatic starting methods

Answer 30

Operator pushes button

Question 31

What should you do if the engine of a turbine doesn't start up within 90 seconds

Answer 31

Abort start up

Question 32

If 50% rpm is not reached in 60 seconds what should you do

Answer 32

Abort cranking

Question 33

Large turbines are fitted with

Answer 33

Serval governors

Question 34

The over speed trip device will

Answer 34

Cut off fuel immediately

Question 35

Gas turbine load control depends upon

Answer 35

The load shaft speed

Question 36

List the five gas turbine alarm singals

Answer 36

High vibration Generator stator high temp Ignition tripped High differential pressure air intake Low lub oil pressure

Question 37

What do you do with high vibrations

Answer 37

Close fuel supply

Question 38

No ignition will result in

Answer 38

Fire or explosion

Question 39

High differential air pressure indicates

Answer 39

Dirty air inlet filters

Question 40

Why is lubrication essential

Answer 40

Lube bearings Cooling of bearings

Question 41

Define a major overhaul turbine maintenance

Answer 41

A total strip down and checking or replacing

Question 42

Define short shutdown turbine maintenance

Answer 42

Clean and replace air inlet filters, wash compressor blading and replace bearings and coupling

Question 43

Aging factor results in

Answer 43

.5% in power and efficiency loss for 1000 hours of services

Question 44

Why do we cool the turbine blades?

Answer 44

So they don't melt

Question 45

HRSG

Answer 45

Heat recovery steam generator

Question 46

Sag in a turbine shaft is called

Answer 46

Bowing

Question 47

What is a regenerator

Answer 47

Takes heat from the exhaust to heat compressed air in the turbine

Question 48

Define cogeneration

Answer 48

Takes hot exhaust gasses to boil water to produce steam Highest efficiency available

Question 49

A major drawback of the gas turbine

Answer 49

Nox emissions are high Low mechanical efficiency

Question 50

The compressor chamber of a gas turbine

Answer 50

Can be driven by the load turbine

Question 51

Many typical steam plant auxiliaries are eliminated with a gas turbine due to its

Answer 51

SIMPLICITY

Question 52

The temperature to which the air can be raised at the turbine inlet is

Answer 52

A indication of the units efficiency

Question 53

DP

Answer 53

Differential Pressure