Questions and answers for exam Preparation

MCQs

Total Questions : 757 | Page 11 of 76 pages

Question 101. In practical operation of any furnace, zero oxygen percentage or theoretical CO₂ percentage in flue gas is rarely achieved, because of

Use of non-preheated combustion air
Use of pulverised solid fuels
Imperfect mixing of fuel & air and infiltration of air
Use of excessive positive draft in the furnace

Discuss Question

Answer: Option C. -> Imperfect mixing of fuel & air and infiltration of air

Question 102. Presence of SO₂ in furnace gases attacks the ferrous metal by way of

Accelerating the rate of scaling
Causing metal embrittlement
Attacking the grain boundaries; particularly severe on low carbon and nickel bearing steels at high temperature
All of the above

Discuss Question

Answer: Option D. -> All of the above

Question 103. The main function of a muffle in the muffle furnace is to

Protect the charge from the effects of the products of combustion
Smooth out temperature inequalities on the combustion side of the muffle wall
Both A & B
Neither A nor B

Discuss Question

Answer: Option C. -> Both A & B

Question 104. Which of the following is a periodic furnace?

Tunnel kiln
Rotary kiln
Soaking pit
Reheating furnace

Discuss Question

Answer: Option C. -> Soaking pit

Question 105. Low stack loss indicates the

Use of sub-stoichiometric air for combustion
Efficient use of fuel
Inefficient use of fuel
Oxygen enrichment of combustion air

Discuss Question

Answer: Option B. -> Efficient use of fuel

Question 106. In furnaces operating at very high temperature (say) 1250°C, e.g. soaking pit), the maximum heat transfer takes place by

Conduction
Convection
Radiation
Can not be predicted

Discuss Question

Answer: Option C. -> Radiation

Question 107. The reason for excessive clinker formation in gas producers is the

Use of coal/coke containing a high % of fines and ash
Use of fuel having too low an ash fusion temperature
Development of hot spots in the fuel bed and an abnormally high rate of gasification
All of the above

Discuss Question

Answer: Option D. -> All of the above

Question 108. In a muffle furnace, the muffle