1) Overall thermal efficiency of a lumpy coal fired suitably designed heating furnace, if operated & maintained properly may be about ____________ percent? a. 10-15 b. 25-30 c. 45-50 d. 65-70
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2) Higher furnace temperature cannot be achieved by use of a lean fuel gas in the furnace by_________________? a. Increasing the draft in the furnace b. Preheating the fuel gas c. Oxygen enrichment of combustion air d. Preheating the combustion air
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3) Heat transfer rate to the charge/stock in a furnace does not depend upon the________________? a. Type of fuels viz. solid, liquid or gaseous b. Flue gas temperature c. Emissivity of refractory walls d. Initial temperature of the charged stock
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4) The amount of combustible escaping unconsumed from the furnace, depends upon the________________? a. Air supplied and furnace temperature b. Burner design (thoroughness of mixing versus stratification) c. Air preheat and the flow of gases in the furnace (mixing by induction, by acceleration or by change of direction) d. All A., B. and C.
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5) Reducing atmosphere is maintained in a__________________? a. Calcination kiln b. Blast furnace c. Soaking pit d. L.D. converter
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6) Heat transfer takes place through a liquid medium surrounding the submerged material under heating, in case of a/an__________________? a. Blast furnace b. Steam boiler c. Salt bath furnace d. Annealing furnace
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7) Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of_________________? a. Graphite powder b. Thoria c. Zircon powder d. Beryllium
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8) Which one is not an induced draught furnace ? a. Blast furnace stove b. Sintering furnace c. High pressure boiler d. None of these
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9) Furnace pressure is normally controlled by regulating the__________________? a. Air pressure b. Fuel gas pressure c. Speed of I.D. fan d. Damper
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10) ______________ is an indirectly heated furnace? a. Open hearth furnace b. Muffle furnace c. Soaking pit d. Reheating furnace
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11)
Fuel economy in furnaces can be achieved by_________________? a. Using oxygen enriched combustion air b. Preheating the combustion air c. Reducing the heat loss through furnace openings & doors d. All A., B. and C.
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12) Ingress of cold air in the furnaces through cracks, charging doors, openings etc ________________? a. Reduces the flue gas temperature and makes the furnace atmosphere oxidising b. Increases the load on the induced draft fan c. Reduces the furnace draught d. All A., B. and C.
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13) Which is the most thermally efficient furnace _______________________? a. Reheating furnace b. Reverberatory furnace c. Rotary kilns d. Boiler furnace
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14) The advantages of firing pulverised coal in the furnace lies in the fact that, it_____________________? a. Permits the use of high ash content coal b. Permits the use of low fusion point ash coal c. Accelerates the burning rate and economises on fuel consumption d. All A., B. and C.
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15) _____________ furnace is not an electric furnace? a. Arc b. Induction c. Pot d. Resistance
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16) To reduce the stack loss, heat recovery from flue gas can be done by_____________________? a. Preheating of cold stock b. Preheating of combustion air c. Steam generation in waste heat boilers d. All A., B. and C.
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17) Size of the combustion chamber of a furnace depends upon the ___________________? a. Heat release rate of the fuel b. Preheat temperature of fuel & air c. Method of mixing the fuel & air d. All A., B. and C.
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18) An electric furnace producing heat by means of an electric arc struck between each of three electrodes and the charge is called ____________ furnace? a. Resistance b. Arc c. Low frequency induction d. None of these
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19) Which of the following is a heat treatment furnace ? a. Muffle furnace b. Annealing furnace c. Reheating furnace d. Rotary kiln
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20) In practical operation of any furnace, zero oxygen percentage or theoretical CO2 percentage in flue gas is rarely achieved, because of__________________? a. Use of non-preheated combustion air b. Use of pulverised solid fuels c. Imperfect mixing of fuel & air and infiltration of air d. Use of excessive positive draft in the furnace
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