Category: Steam and Gas Turbines Objective Questions

Steam Turbine Interview Questions and Answers on “Heat and Steam Rate”.

1. Heat rate defines how much energy is to be expanded for obtaining a unit of useful work.
a) True
b) False

Answer: a
Clarification: Heat rate means the amount of energy that must be expanded for obtaining an unit of useful work.

2. What is heat rate in turbine?
a) Heat required for unit of power generated in specific conditions and specific fuel burning
b) Amount of heat required to expand turbine blades
c) Amount of heat required to increase pressure of steam
d) None of the mentioned

Answer: a
Clarification: Heat rate in turbines is defined as heat required to generate unit power in turbine at specific fuel being burned at specific conditions.

3. For calculating heat rate in steam turbines enthalpy is calculated.
a) False
b) True

Answer: b
Clarification: Heat rate can be calculated by using enthalpy method.

4. Steam turbine governing can be defined as __________
a) increasing the steam speed
b) adjusting the governors for particular speeds
c) controlling the flow rate of steam
d) none of the mentioned

Answer: c
Clarification: Governors are used to control the fuel needed to the load and they are no way related to the steam turbine governing. Steam turbine governing is controlling the flow rate of steam.

5. Why is steam turbine governing used?
a) To increase the steam speed
b) To maintain steam speed constant
c) To decrease the steam speed
d) None of the mentioned

Answer: b
Clarification: Flow rate if steam is controlled to maintain the constant speed.

6. In nozzle governing the flow rate is controlled by ____________
a) opening and closing the valves at nozzle
b) adding more number of nozzles
c) increasing nozzle efficiency
d) none of the mentioned

Answer: a
Clarification: Opening and closing of valves at nozzle is called nozzle governing.

7. During overload of turbines __________ are used.
a) throttle governing
b) nozzle valves
c) bypass governing
d) none of the mentioned

Answer: c
Clarification: During overload conditions fresh steam is added into later stages called as bypass governing.

8. When is emergency governing used?
a) Speed of shaft increased above 110%
b) When turbine is shut down due to overload
c) When Low steam is entering
d) None of the mentioned

Answer: a
Clarification: When speed of shaft is increased to 110% then emergency governing is used to control the speed.

9. When balancing of the turbine is disturbed ___________ is used.
a) Potter governor
b) Centrifugal governor
c) Emergency governor
d) None of the mentioned

Answer: c
Clarification: Emergency governor is also used when balancing of the turbine is disturbed.

10. When lubrication is failed _____________ is used.
a) Centrifugal governor
b) Emergency governor
c) Potter governor
d) None of the mentioned

Answer: b
Clarification: Emergency governor is used in all emergency situations like when the lubrication system is failed, when speed is increased when balancing is disturbed etc.

Steam Turbines for Interviews,

Steam and Gas Turbines Multiple Choice Questions on “Relationship between Velocity Ratios”.

1. Velocity ratio is represented by ___________
a) Alpha
b) Beta
c) Sigma
d) None of the mentioned
Answer: c
Clarification: Velocity ratio is represented by sigma.

2. For single stage impulse turbine optimum sigma value lies between ____________
a) 0.4 and 0.6
b) 0.2 and 0.4
c) 0.1 and 0.3
d) none of the mentioned
Answer: a
Clarification: 0.4 and 0.6 are the boundary values for sigma in single stage impulse turbine which can be found from graph plotted between sigma and efficiency.

3. For two stage impulse turbine optimum sigma value lies between __________
a) 0.3 and 0.5
b) 0.2 and 0.4
c) 0.1 and 0.5
d) none of the mentioned
Answer: b
Clarification: For two stage impulse turbine sigma value lies in between 0.2 and 0.4 which can be found out from graph plotted between sigma value and efficiency.

4. For reaction turbines the optimum sigma value lies between _____________
a) 0.8 and 1.0
b) 0.6 and 1.0
c) 0.4 and 0.8
d) none of the mentioned
Answer: a
Clarification: For reaction turbines sigma value lies between 0.8 and 1.0 which can be found out from graph plotted between sigma and efficiency.

5. Speed of the blade to speed of the gas ratio can be denoted by ___________
a) Alpha
b) Sigma
c) Gamma
d) None of the mentioned
Answer: b
Clarification: Blade to gas speed ratio is known as velocity ratio and it can be represented by sigma.

6. Best velocity ratio for four row impulse turbine is ________
a) one seventh
b) one sixth
c) half
d) none of the mentioned
Answer: a
Clarification: The best velocity ratio for four row impulse turbine is one seventh.

6. Efficiency of the four row impulse turbine with a velocity ratio of one seventh is ______
a) 55%
b) 44%
c) 34%
d) 77%
Answer: b
Clarification: Efficiency of four row impulse turbine with a velocity of one seventh is 44% which was found from graph plotted against efficiency and velocity ratio.

7. Velocity ratio is the integral of ________ of the velocity in each row.
a) fourth power
b) cube
c) square
d) none of the mentioned
Answer: c
Clarification: Velocity ratio is the integral of square of velocity in each row.

8. Velocity ratio is directly proportional to square of velocity.
a) True
b) False
Answer: b
Clarification: Velocity ratio is directly proportional to integral of square of velocity in each row.

9. When velocity in each row increases its velocity ratio __________
a) decreases
b) remains constant
c) increases
d) none
Answer: c
Clarification: When velocity in each row increases its velocity ratio also increases.

10. Velocity ratio is directly proportional to velocity in each row.
a) True
b) False
Answer: b
Clarification: Velocity in each row is inversely proportional to velocity ratio.

contest

Steam and Gas Turbines Multiple Choice Questions on “Control and Supervisory Instruments”.

1. Radial vibration measurement measures ____________
a) unbalanced masses
b) cracked shafts
c) oil whirl
d) all of the mentioned
Answer: d
Clarification: Radial vibration measurement measures all the unbalanced masses, cracked shafts and also oil whirls.

2. Vibration measurements in steam turbines can be made in _______ planes.
a) 1
b) 2
c) 1 or 2
d) 4
Answer: c
Clarification: Vibration measurements in steam turbines can be measured in single plane or two planes.

3. Absolute shaft measurement is done when __________
a) weight of the rotating assemble is five times more than casing
b) weight of rotating assembly is two time more than the casing
c) weight of the rotating assembly is thrice the casing weight
d) none of the mentioned
Answer: a
Clarification: Absolute shaft measurement measures the shaft motion with respect to the free space. It is done when weight of the shaft assembly is five times more than the weight of casing.

4. Phase measurement is required for accurate balancing of the rotor.
a) True
b) False
Answer: a
Clarification: Phase measurement is required for accurate balancing of any rotor. Because phase is defined as angle between reference mark and heavy spot on the rotor.

5. Eccentricity measurement is used to indicate ______
a) bent shafts
b) when the rotor can be bought to the high speeds
c) bent shafts and when the rotor can be bought to the high speeds
d) none of the mentioned
Answer: c
Clarification: Eccentricity measurement makes us to know about the sag or bow in a rotor which helps us to get knowledge about whether to increase the speed or not.

6. DE measurement is used to get the knowledge about distance between case and rotor.
a) True
b) False
Answer: a
Clarification: As turbine casing has more weight than the rotor, when turbine is under operation it should be taken care that there should not be any contact between turbine and casing due to thermal expansion as turbine has more expansion when compared to the casing.

7. Rotor thrust measurement is done in order to _______
a) monitor thrust
b) monitor bearing wear
c) monitor thrust & bearing wear
d) none of the mentioned
Answer: c
Clarification: Rotor thrust measurement is done in order to monitor thrust and also bears wear.

8. Thrust position measurements are taken within _____ inches of thrust bearing.
a) 10
b) 12
c) 20
d) 24
Answer: b
Clarification: Thrust position measurement is done within 12 inches of thrust bearing.

9. Thrust measurement taken out of 12 inches are effected by ______
a) thrust forces
b) thrust forces & thermal expansions
c) thermal expansions
d) none of the mentioned
Answer: c
Clarification: Measurements taken out of q2 inches are generally effected by thermal expansions.

10. Valve position measurement is used to measure how much valve is used.
a) True
b) False
Answer: a
Clarification: Valve position measurement is used to measure how much the valve is opened, mainly throttle valve which gives us information about how much percentage the load can be increased.

Steam and Gas Turbines Multiple Choice Questions on “Economic Aspect of Regenerator Design”.

1. In two stat regenerator system ________ stage is known as partial combustion mode.
a) first
b) last
c) intermediate
d) none of the mentioned
Answer: a
Clarification: In two stage regenerator system first stage combusts CO with all the available oxygen.

2. Amount of coke burnt is _______ in first stage of two stage regenerator.
a) varied
b) constant
c) Zero
d) none of the mentioned
Answer: b
Clarification: Amount of coke burned varies in first stage of two stage regenerator.

3. In two stage regenerators catalyst deactivation rates are _______
a) low
b) high
c) medium
d) none of the mentioned
Answer: a
Clarification: The environment produced in two stage regenerator is gentle and hence catalyst deactivation rates are low.

4. ________ catalyst deactivation rates are benefited as catalysts are poisonous in nature.
a) medium
b) high
c) less
d) none of the mentioned
Answer: c
Clarification: Less catalyst deactivation rates are benefited as catalysts are poisonous in nature.

5. In two stage regenerator system catalyst cooler is added.
a) True
b) False
Answer: a
Clarification: In a two stage regenerator system a catalyst cooler is present.

6. Cooling capacity of catalyst cooler is _________ MMBtu/h.
a) 120
b) 100
c) 140
d) 200
Answer: c
Clarification: Cooling capacity of catalyst cooler is 140MMBtu/h.

7. When cooling system is needed to be increased no of catalyst coolers are _________ by two or three.
a) increased
b) decreased
c) not related
d) none of the mentioned
Answer: a
Clarification: When cooling system is needed to be increased no of catalyst coolers are increased to two or three.

8. In two stage FCC regenerator FCC stands for fluid catalytic cracking unit.
a) True
b) False
Answer: a
Clarification: In two stage FCC regenerator FCC stands for fluid catalytic cracking unit.

9. Total no of FCC regenerators operated in India are ______
a) 20
b) 10
c) 5
d) 15
Answer: b
Clarification: Total no of 10 FCC regenerators are operated India.

10. Minimum obtained catalyst loss is ________ Kg/day.
a) 500
b) 400
c) 420
d) 360
Answer: c
Clarification: Minimum obtained catalyst loss is 420kg/day.

Steam and Gas Turbines Multiple Choice Questions on “Compressor Parts of Gas Turbines”.

1. Airfoils are present in the ________ of the compressor.
a) inlet
b) outlet
c) middle
d) none of the mentioned
Answer: a
Clarification: Airfoils are used to produce swirl motion in the inlet. Hence they are present in the inlet.

2. Valve’s are present in the ________ of the centrifugal compressor.
a) middle
b) outlet
c) inlet
d) none of the mentioned
Answer: c
Clarification: Valve’s are present in the inlet of the centrifugal compressor. Valves are used to inject working fluids into the compressor.

3. Stationary vanes are present in the ________ of the compressor.
a) outlet
b) inlet
c) middle
d) none of the mentioned
Answer: b
Clarification: Stationary vanes are present in the inlet of the compressor. Stationary vanes help in directing the fluid into required direction.

4. Compressor belts are present in order to avoid ________ losses.
a) pressure
b) temperature
c) pressure & temperature
d) none of the mentioned
Answer: a
Clarification: Compressor belts are present to provide tight seal so that pressure loss doesn’t take place.

5. Unloader valves are used to _________ the load on the compressor.
a) increase
b) deccrease
c) unloader does not alter load
d) none of the mentioned
Answer: b
Clarification: Unloader valves are used to decrease the load on the compressor. When the compressor reaches maximum load then unloader is used.

6. Check valves are used in the compressor.
a) True
b) False
Answer: a
Clarification: Check valves are used to check whether the required pressure is maintained or not.

7. _____________ are present in the centrifugal impeller.
a) Rotating vanes
b) Stationary vanes
c) Rotating & Stationary vanes
d) None of the mentioned
Answer: c
Clarification: Rotating vanes increases the energy of the working gas. Stationary vanes are used to direct the flow of the steam.

8. Exit velocity of the gas in the centrifugal compressor is equal to __________
a) speed of sound
b) double the speed of sound
c) half the speed of sound
d) none of the mentioned
Answer: a
Clarification: Exit velocity of the gas in the centrifugal compressor is equal to speed of the sound. Outlet pressure is very high in the compressor.

9. In compressor diffuser is used to convert ___________ of the gas into the velocity.
a) potential energy
b) kinetic energy
c) potential & kinetic energy
d) none of the mentioned
Answer: b
Clarification: Diffuser converts kinetic energy of the gas into velocity. In diffuser pressure is reduced which leads to increase in velocity.

10. Bernoulli’s principle is used in determining the performance of diffuser.
a) True
b) False
Answer: a
Clarification: Performance of diffuser can be determined by using bernoulli’s theorem.