# Practice Test: Question Set - 19

1. The economiser is used in boilers to
(A) Increase thermal efficiency of boiler
(B) Economize on fuel
(C) Extract heat from the exhaust flue gases
(D) Increase flue gas temperature

2. The reheat factor is the ratio of the
(A) Cumulative heat drop to the isentropic heat drop
(B) Isentropic heat drop to the heat supplied
(C) Total useful heat drop to the total isentropic heat drop
(D) None of the above

3. Which of the following statement is correct?
(A) A fire tube boiler occupies less space than a water tube boiler, for a given power
(B) Steam at a high pressure and in large quantities can be produced with a simple vertical boiler
(C) A simple vertical boiler has one fire tube
(D) All of the above

4. The three "Ts" for good combustion are
(A) Temperature, time, and turbulence
(B) Total air, true fuel, and turbulence
(C) Thorough mixing, total air and temperature
(D) Total air, time, and temperature

5. The value of the reheat factor varies from
(A) 1.02 to 1.06
(B) 1.08 to 1.10
(C) 1.2 to 1.6
(D) 1.6 to 2

6. Cut-off governing of steam engines is a method of controlling the engine output by varying
(A) Volume of intake steam
(B) Pressure of intake steam
(C) Temperature of intake steam
(D) All of these

7. The size of a boiler drum in pulverized fuel fired boiler, as its size and capacity, (steam pressure and flow ratings) increase
(A) Increases
(B) Decreases
(C) Remains unchanged
(D) Increases/decreases depending on steam temperature requirements

8. A nozzle is said to be a divergent nozzle
(A) When the cross-section of the nozzle increases continuously from entrance to exit
(B) When the cross-section of the nozzle decreases continuously from entrance to exit
(C) When the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
(D) None of the above

9. The theoretical indicator diagram of a simple steam engine is based upon the assumption that
(A) There is no pressure drop due to condensation
(B) Steam is admitted at boiler pressure and exhausted at condenser pressure
(C) The expansion (or compression) of the steam is hyperbolic
(D) All of the above

10. If partial pressure of air and steam be ‘pa’ and ‘ps’ respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
(A) ps - pa
(B) pa - ps
(C) pa + ps
(D) None of these

11. In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is
(A) Low
(B) Very low
(C) High
(D) Very high

12. The high steam and low water safety valve is used to blow off steam when the
(A) Steam pressure exceeds the working pressure
(B) Water level in the boiler becomes too low
(C) Both (A) and (B)
(D) None of the above

13. On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
(A) Horizontal straight line
(B) Vertical straight line
(C) Straight inclined line
(D) Curved line

14. The critical pressure gives the velocity of steam at the throat
(A) Equal to the velocity of sound
(B) Less than the velocity of sound
(C) More than the velocity of sound
(D) None of these

15. The high pressure and low pressure cylinders in a Woolf type compound engine are regarded as having cranks
(A) 180° to each other
(B) 90° to each other
(C) 0° to each other
(D) None of these

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