All Free Chemical Engineering MCQs with Answers

• A. Solid fuels
• B. Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.)
• C. Both A. and B.
• D. Neither A. nor B.

Explanation: Solid fuel cannot be conveniently preheated before firing, and hydrocarbon-rich fuel gases are generally not preheated because heating can…

• A. Pulverised coal
• B. Furnace oil
• C. Coke oven gas
• D. Blast furnace gas/mixed gas

Explanation: Blast-furnace stoves burn blast-furnace gas, often supplemented by mixed gas, to heat the refractory checkerwork.

• A. Roasting/reduction of ores
• B. Annealing steel coil
• C. Heating air
• D. Steel melting

Explanation: A reverberatory furnace transfers heat mainly by radiation from the flame and hot roof to the charge, making it suitable for roasting and…

• A. Coke oven
• B. High pressure boiler
• C. Beehive coke oven
• D. Blast furnace stoves

Explanation: A high-pressure boiler commonly uses an induced-draught fan to draw flue gases through the furnace and boiler passes before discharge.

• A. Natural draft furnace
• B. Tunnel Kiln
• C. Rotary Kiln
• D. Batch furnace

Explanation: Cement manufacture uses a rotary kiln, in which the inclined rotating shell continuously moves and mixes the raw meal through drying…

• A. Low reactivity of carbonised residue containing high proportion of iron & sulphur
• B. Low forced draft & fuel bed temperature
• C. Thick firebed and preheated primary air
• D. All A., B. and C.

Explanation: Poorly reactive residue, inadequate draught, unsuitable bed conditions, a thick firebed and preheated primary air can create local…

• A. < 2
• B. < 5
• C. < 8
• D. < 10

Explanation: A well-adjusted gaseous-fuel furnace aims for only a small excess of air, commonly keeping flue-gas oxygen below about 2%.

• A. Fans
• B. Arrangement of heating stock in the furnaces
• C. Location of outlet ports and heating & combustion devices
• D. All A., B. and C.

Explanation: Gas circulation in a furnace is controlled by fan action, the arrangement of the stock, and the positions of outlets and heating or…

• A. Thermal efficiency of the process
• B. Sources of heat losses
• C. Scope of reduction of heat losses
• D. All A., B. and C.

Explanation: A furnace heat balance accounts for heat supplied and heat used or lost, so it can give efficiency, identify loss sources, and show where…

• A. Reverberatory furnace
• B. Walking beam reheating furnace
• C. Tower furnace
• D. Tunnel kiln

Explanation: A reverberatory furnace is directly fired because combustion gases transfer heat directly to the charge, usually by radiation from the…

• A. Hood annealing furnace
• B. Both A. and B.
• C. Muffle furnace
• D. Neither A. nor B.

Explanation: A muffle furnace heats the charge through a surrounding hot wall rather than exposing it directly to combustion gases.

• A. Higher calorific value
• B. Smokeless burning
• C. Better combustion
• D. Less erosion on furnace wall

Explanation: Pulverising coal greatly increases its surface area, allowing rapid and more complete mixing with air and therefore better combustion.

• A. Economiser
• B. Steam superheater
• C. Air preheater
• D. All A., B. and C.

Explanation: Flue-gas heat can be recovered successively in an economiser for feedwater, a superheater for steam, and an air preheater for combustion…

• A. Regenerator
• B. Economiser
• C. Ceramic recuperator
• D. Waste heat boiler

Explanation: A regenerator stores heat in a solid matrix during one part of the cycle and gives it back during another, so its operation is periodic.

• A. Reduction in scale losses
• B. Increase in flame temperature
• C. Increase in calorific value of the fuel
• D. Saving in fuel consumption

Explanation: Preheated air raises flame temperature, reduces scale formation and saves fuel by improving heat transfer and combustion.

• A. Rotary kilns
• B. Blast furnace
• C. Coke oven heating chamber
• D. Blast furnace stoves

Explanation: Blast-furnace stoves are regenerative heaters operated in alternating heating and air-heating cycles, so they are periodic furnaces.

• A. None of these
• B. Gas velocity in furnace
• C. Ratio of wall surface to surface of stock
• D. Size of the furnace

Explanation: Furnace capacity depends on furnace size, gas velocity and the relative wall-to-stock surface area because these affect heat-transfer rate…

• A. Change in volume during a change of temperature
• B. All A., B. and C.
• C. Furnace pressure in conjunction with draft in flues
• D. Difference in density between hot and cold gases

Explanation: Gas circulation may result from thermal expansion, density differences between hot and cold gases, and pressure differences produced by…

• A. Elimination of cold spot at the bottom of the charge
• B. Increase in heating capacity/m2 of floor space
• C. Reduction in the temperature of furnace gases
• D. Protection of the periphery of the charge from excessive radiation

Explanation: Underfiring is used to remove the cold region near the bottom, shield the charge edges from excessive radiation and lower the furnace-gas…

• A. Store smaller quantity of waste heat
• B. Are lighter & compact
• C. Involve higher initial cost
• D. All A., B. & C.

Explanation: A regenerator uses refractory checkerwork to store heat cyclically and generally needs a heavier, more expensive arrangement than a…