Furnace Technology

41.Heat transfer takes place through a liquid medium surrounding the submerged material under heating, in case of a/an

1. Blast furnace
2. Steam boiler
3. Salt bath furnace
4. Annealing furnace

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42.Higher furnace temperature cannot be achieved by use of a lean fuel gas in the furnace by

1. Increasing the draft in the furnace
2. Preheating the fuel gas
3. Oxygen enrichment of combustion air
4. Preheating the combustion air

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43.If fuel and air are mixed ahead of the burner, it is called a/an _________ burner.

1. Premix
2. Outside mixing type
3. Rotary
4. Diffusion

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44.If the flame is produced under the hearth and then sweeps up into the heating chamber, this is called a/an _________ furnace.

1. Sidefired
2. Underfired
3. Covered
4. Recirculating

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45.In a furnace employing forced draught as compared to induced draught,

1. Air is sucked in, so air leaks are more and hence the furnace efficiency is reduced
2. The fan operates hot and hence blades are liable to corrosion and erosion
3. Positive pressure exists in the furnace
4. None of these

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46.In a furnace operation, which is not preheated?

1. Solid fuels
2. Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.)
3. Both (A) and (B)
4. Neither (A) nor (B)

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47.In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the

1. Rate of firing and emissivity of flame
2. Thermal conductivity of the charge & structural materials of furnace
3. Nature of process; whether batch, continuous or intermittent
4. All (A), (B) and (C)

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48.In a heating process, a heat flow diagram in which the quantities of heat in the various items of a heat balance are represented by the width of a band is called the

1. Ostwald chart
2. Cox chart
3. Sankey diagram
4. None of these

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49.In a muffle furnace, the muffle

1. Retards the heat transfer
2. Assists in temperature equalisation in the charge
3. Permits the use of controlled atmosphere for the protection of stock
4. All (A), (B) and (C)

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50.In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of

1. Transportation of coal
2. Drying of coal
3. Combustion of coal by supplying it around the burner
4. Preheating the primary air

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