Overall thermal efficiency of a lumpy coal fired suitably designed heating furnace, if operated & maintained properly may be about ____________ percent?

Related Mcqs:

1. Thermal efficiency of blast furnace stoves used for heating blast (air) may be about _____________ percent?

   A. 20
   B. 40
   C. 60
   D. 80

2. The thermal efficiency of a steel slab reheating furnace (walking beam type) may be about ____________ percent?

   A. 15
   B. 40
   C. 70
   D. 85

3. Thermal efficiency of an open hearth furnace may be about _____________ percent?

   A. 5
   B. 20
   C. 50
   D. 80

4. Combustion of furnace oil in a furnace (soaking pit) with preheated combustion air at 400°C results in saving of about __________ percent furnace oil as compared to its combustion with atmospheric air, if the flue gas outlet temperature from the soaking pit is 1200°C ?

   A. 5
   B. 60
   C. 20
   D. 40

5. While the fuel fired furnace can be used upto a maximum temperature of about 1700°C, the electric furnace can be used upto a temperature of about _____________ °C?

   A. 2000
   B. 3000
   C. 4500
   D. 6000

6. Oxygen percentage in the flue gas coming out of a gaseous fuel fired furnace should be ideally about _____________ percent?

   A. < 2
   B. < 5
   C. < 8
   D. < 10

7. The thermal efficiency of an air/fuel gas preheating recuperator may be as high as _____________ percent?

   A. 50
   B. 65
   C. 85
   D. 99

8. Maximum thermal efficiency of boiler may be about _____________ percent?

   A. 10
   B. 25
   C. 65
   D. 90

9. Thermal efficiency of a limestone calcination rotary kiln may be around ______________ percent?

   A. 20
   B. 40
   C. 65
   D. 80

10. Neutral atmosphere is maintained in a/an ____________ furnace?

    A. Cold rolled steel coil annealing
    B. Open hearth
    C. Soaking pit
    D. Walking beam reheating