21. Ceramic recuperators (made of SiC) is economical, only when used for preheating combustion air above __________ °C.
250
650
850
1000
✅ The correct answer is option B.
Furnace Technology MCQs
22. 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.
2000
3000
4500
6000
✅ The correct answer is option C.
23. Regenerators compared to the recuperators for the same duty
Occupy more space
Are less costly
Are of smaller size
All of the above
✅ The correct answer is option A.
24. Thermal efficiency of an open hearth furnace may be about __________ percent.
5
20
50
80
✅ The correct answer is option B.
25. Maximum thermal efficiency of boiler may be about __________ percent.
10
25
65
90
✅ The correct answer is option D.
26. Which of the following is not a recuperative furnace?
Soaking pit
Reheating furnace
Steamboiler
Coke oven
✅ The correct answer is option D.
27. 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.
5
60
20
40
✅ The correct answer is option C.
28. In a furnace operation, which is not preheated?
Solid fuels
Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.)
Both A and B
Neither A nor B
✅ The correct answer is option C.
29. Which of the following is a periodic furnace?
Tunnel kiln
Rotary kiln
Soaking pit
Reheating furnace
✅ The correct answer is option C.
30. In a furnace employing forced draught as compared to induced draught,
Air is sucked in, so air leaks are more and hence the furnace efficiency is reduced
The fan operates hot and hence blades are liable to corrosion and erosion
Positive pressure exists in the furnace
None of these
✅ The correct answer is option C.