1) Metallic recuperators are not used for waste heat recovery, if the hot flue gas temperature is above _____________ °C, because corrosion prevails at higher temperatures? a. 350 b. 750 c. 1050 d. 1250
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2) In reverberatory furnace, charge is heated mainly by__________________? a. Conduction b. Natural convection c. Radiation of heat from the roof of the combustion chamber d. None of these
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3) Which one shows the diagrammatic heat balance in a furnace ? a. Sankey diagram b. Cox chart c. Ostwald chart d. None of these
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4) _____________ atmosphere is maintained inside an iron blast furnace? a. Oxidising b. Reducing c. Inert d. Decarburising
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5) If the flame is produced under the hearth and then sweeps up into the heating chamber, this is called a/an ______________ furnace? a. Sidefired b. Underfired c. Covered d. Recirculating
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6) Large tonnage of refractory bricks are dried in a_____________________? a. Shaft furnace b. Rotary hearth furnace c. Tunnel kiln d. Muffle furnace
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7) A refractory wall separating the stock and the source of heat is provided in a__________________? a. Updraft kiln b. Muffle furnace c. Continuous furnace d. None of these
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8) Turndown ratio of a burner gives an idea of the ______________ in the furnace? a. Range of fuel firing rates b. Volume of the combustion chamber c. Maximum heat input rate only d. Minimum heat input rate only
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9) Which is a continuous furnace ? a. Coke ovens b. Annealing furnace c. Glass tank furnace d. None of these
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10) Overfire burning in a furnace is a phenomenon characterised by____________________? a. Supply of excess fuel b. Supply of excess air c. Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air d. None of these
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11) Regenerators are normally provided in the____________________? a. Glass melting furnace b. Open hearth furnace c. By product coke ovens d. All A., B. and C.
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12) Which furnace employs preheating, heating and soaking zones ? a. Soaking pit b. Reheating furnace c. Open hearth furnace d. Cupola
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13) Fuel economy in an industrial furnace operation cannot be achieved by the use of__________________? a. Stoichiometric combustion air b. Non-preheated combustion air c. Combustion air not enriched with oxygen d. Recuperators
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14) Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case of complete combustion of_________________? a. Furnace oil with air b. Furnace oil with oxygen c. Blast furnace gas with air d. Blast furnace gas with oxygen
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15) Which of the following is not an additive for flue gases from furnace to reduce its dewpoint ? a. Ammonia b. Fine dolomite c. Alkaline powders d. None of these
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16) The function of an economiser in a boiler is to preheat the _____________________? a. Feedwater b. Combustion air c. Pulverised coal d. Furnace oil
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17) Which of the following furnaces will have maximum thermal efficiency ? a. Soaking pits b. Walking beam reheating furnace c. Boiler furnace d. Rotary kilns
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18) Ostwald charts are meant for__________________? a. Computing the excess/deficiency of combustion air b. Calculation of flue gas temperature c. Computation of flue gas analysis d. None of these
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19) Pick out the wrong statement ? a. Addition of methane to the furnace atmosphere reduces decarburising by hydrogen b. Nitrogen in presence of steam decor-burises high carbon steel, whereas hydrocarbon gases carburise the surface of steel at annealing temperatures c. Active nitrogen (formed by cracking ammonia at the metal surface) cause nitride formation with increase in surface hardness d. None of these
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