All Free Chemical Engineering MCQs with Answers

• A. All A., B. and C.
• B. Preheating the combustion air
• C. Reducing the heat loss through furnace openings & doors
• D. Using oxygen enriched combustion air

Explanation: Oxygen enrichment and combustion-air preheating reduce the energy needed for combustion and lower flue-gas heat losses, while sealing…

• A. Open hearth furnace
• B. Muffle furnace
• C. Soaking pit
• D. Reheating furnace

Explanation: A muffle furnace heats the charge indirectly through a surrounding refractory chamber, so the material does not contact the flame or…

• A. Air pressure
• B. Fuel gas pressure
• C. Speed of I.D. fan
• D. Damper

Explanation: Furnace pressure is commonly adjusted with the flue-gas damper, which changes the resistance to gas discharge and hence the pressure…

• A. Blast furnace stove
• B. Sintering furnace
• C. High pressure boiler
• D. None of these

Explanation: A blast-furnace stove is normally operated with forced draught during combustion, rather than as an induced-draught furnace.

• A. Graphite powder
• B. Zircon powder
• C. Thoria
• D. Beryllium

Explanation: Zircon-based ceramic coatings provide a high-emissivity refractory surface, increasing radiative heat transfer to the charge.

• A. Calcination kiln
• B. Soaking pit
• C. Blast furnace
• D. L.D. converter

Explanation: A blast furnace contains carbon monoxide and hydrogen-rich gases produced from coke and injected fuel, which reduce iron oxides as the…

• A. Air supplied and furnace temperature
• B. All A., B. and C.
• C. Air preheat and the flow of gases in the furnace (mixing by induction, by acceleration or by
• D. change of direction)
• E. Burner design (thoroughness of mixing versus stratification)

Explanation: Unburned combustible losses depend on the available air and furnace temperature, burner mixing quality, air preheat, and gas-flow patterns…

• A. Temperature
• B. Time
• C. Nature of atmosphere
• D. All A., B. and C.

Explanation: Scaling is accelerated by higher temperature, longer exposure time, and an oxidising or otherwise favourable furnace atmosphere.

• A. Use of coal/coke containing a high % of fines and ash
• B. All A., B. and C.
• C. Development of hot spots in the fuel bed and an abnormally high rate of gasification
• D. Use of fuel having too low an ash fusion temperature

Explanation: Clinker forms when ash softens and fuses, especially with low ash-fusion fuel, hot spots, excessive local gasification, or high fines and…

• A. Physical nature, ash content and fineness of the coal
• B. Amount of excess air supplied and load on the boiler
• C. Type of burner and combustion chamber
• D. All A., B. and C.

Explanation: Unburnt coal carried with fly ash depends on coal fineness, ash content, and physical properties, as well as excess air, boiler load…

• A. Weight heated/hr
• B. Weight heated/furnace volume
• C. Weight heated/hr/furnace volume
• D. None of these

Explanation: Specific heating capacity measures furnace throughput relative to furnace size, so its unit is weight heated per hour per unit furnace…

• A. Ton stock/hr/m2 hearth area
• B. Ton stock/hr
• C. Ton stock/m2 hearth area
• D. Both B. and C.

Explanation: Furnace loading is a rate of production normalised by hearth area, expressed as tons of stock heated per hour per square metre of hearth.

• A. 20
• B. 40
• C. 65
• D. 80

Explanation: A limestone-calcination rotary kiln typically has a thermal efficiency of roughly 40%, although the exact value varies with kiln design…

• A. 10
• B. 25
• C. 65
• D. 90

Explanation: Modern well-designed boilers can transfer roughly 80 to 90% of the fuel heat to the steam, so about 90% is a reasonable maximum.

• A. Saving in fuel consumption
• B. Reduction in scale losses
• C. Increase in flame temperature
• D. All A., B. and C.

Explanation: Preheating combustion air recovers heat that would otherwise leave with the flue gas, thereby reducing fuel consumption, limiting scale…

• A. 20
• B. 40
• C. 60
• D. 80

Explanation: Blast-furnace stoves are regenerative heat exchangers and commonly achieve thermal efficiencies of about 80%.

• A. Potteries
• B. Stainless steel
• C. Glass
• D. Refractory bricks

Explanation: A pot furnace with regenerative or recuperative heating is a furnace used for melting glass, where the charge is held in refractory pots.

• A. Slabs
• B. Coils
• C. Sheets
• D. Ingots

Explanation: Soaking pits heat steel ingots uniformly throughout their cross-section before rolling.

• A. Both A. and B.
• B. Cement manufacture
• C. Calcination of limestone & dolomite
• D. Neither A. nor B.

Explanation: Rotary kilns provide continuous high-temperature processing and are used both to calcine limestone or dolomite and to manufacture cement…

• A. Same
• B. Less
• C. More
• D. Either more or less; depends on the flue gas density

Explanation: For the same mass flow and draught pressure, forced-draught equipment handles cooler, denser air and therefore a smaller volume.