Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by_________________?

Related Mcqs:

1. One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is____________________?

   A. 100
   B. 900
   C. 9000
   D. 10000

2. The delivery pressure of boiler feed water pump compared to the boiler steam pressure is___________________?

   A. Same
   B. Slightly less
   C. Slightly more
   D. Much more

3. A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness ______________ metre?

   A. 0.01
   B. 0.1
   C. 0.25
   D. 0.5

4. A high pressure boiler generates steam at a pressure greater than _____________________ kg/cm2 ?

   A. 10
   B. 30
   C. 50
   D. 80

5. The amount of water evaporated in kg per kg of fuel burnt in a boiler is called the ______________ of a boiler ?

   A. Evaporative capacity
   B. Evaporation efficiency
   C. Thermal efficiency
   D. Steam load

6. The most detrimental impurity in high pressure boiler feed water is ___________________?

   A. Suspended salt
   B. Dissolved salt
   C. Silica
   D. Turbidity

7. In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be__________________?

   A. Conduction
   B. Radiation
   C. Natural convection
   D. Forced convection

8. The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by (T1 – T2)/T1. The co-efficient of performance (CO.P.) of a Carnot heat pump operating between T1 and T2 is given by_________________?

   A. T1/(T1-T2)
   B. T2/(T1-T2)
   C. T1/T2
   D. T2/T1

9. Which of the following is a boiler accessory i.e., not a boiler mounting ?

   A. Blow off cock
   B. Feed check valve
   C. Feed water pump
   D. Stop valve

10. The most prominent single cause of corrosion in boiler-tubes, drums, economisers and steam superheaters in a thermal power plant boiler is the_______________?

    A. Water alkalinity & leakage
    B. Hydrazine addition during feed water treatment
    C. Release of non-condensable gas from water in the boiler
    D. Scale formation