Steam Nozzles and Turbines online Practice Test - Set 10 - ObjectiveBooks

Practice Test: Question Set - 10

1. Which is not the correct statement about moisture in coal?
(A) Inherent moisture and surface moisture are different things
(B) In some coals moisture may be present up to 40%
(C) Some moisture in coal helps in better burning which is not possible with completely dry coal
(D) It increases thermal efficiency

2. The friction present between the steam and the nozzle surfaces reduces the heat drop by
(A) 10 to 15%
(B) 15 to 25%
(C) 25 to 40%
(D) 40 to 60%

3. The draught in locomotive boilers is produced by a
(A) Chimney
(B) Centrifugal fan
(C) Steam jet
(D) None of these

4. Stoichiometric quantity of air is the
(A) Air present in atmosphere at NTP conditions
(B) Air required for complete combustion of fuel with no excess air
(C) Air required for optimum combustion so as to have reasonable excess air
(D) Air required to convert CO into CO₂

5. The impulse reaction turbine has its driving force
(A) As an impulsive force
(B) As a reaction force
(C) Partly as an impulsive force and partly as a reaction force
(D) None of the above

6. The average operating pressure of Benson boiler is
(A) 100 bar
(B) 150 bar
(C) 200 bar
(D) 250 bar

7. Pick up the wrong statement about critical condition of steam
(A) Latent heat is zero
(B) Liquid directly becomes steam
(C) Specific volume of steam and liquid is same
(D) This is the maximum pressure limit

8. In reaction turbines, the axial thrust is due to
(A) Pressure drop across the rotor
(B) Change in axial velocity
(C) Both (A) and (B)
(D) None of these

9. The draught produced by a steam jet issuing from a nozzle placed in the chimney is called
(A) Induced steam jet draught
(B) Chimney draught
(C) Forced steam jet draught
(D) None of these

10. A packaged boiler is one in which various parts like firing equipment, fans, feed pumps and automatic controls are
(A) Supplied by same manufacturer loose and assembled at site
(B) Supplied mounted on a single base
(C) Purchased from several parties and packed together at site
(D) Packaged boiler does not exist

11. The impulse turbine rotor efficiency will have a maximum value of 0.5 cos 2α, where α is the nozzle exit flow angle, if the
(B) Blade velocity coefficient is unity
(C) Blades are equiangular and frictionless

12. Lancashire boiler is used where working pressure and power required are
(A) Low
(B) Moderate
(C) High
(D) None of these

13. Fusible plug for boilers is made of fusible metal containing tin, lead, and
(A) Bismuth
(B) Copper
(C) Aluminium
(D) Nickel

14. Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
(A) A steam turbine develops higher speeds
(B) The efficiency of steam turbine is higher
(C) The steam consumption is less
(D) All of these

15. Which of the following is not a boiler mounting?
(A) Blow off cock
(B) Feed check valve
(C) Economiser
(D) Fusible plug

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