All Free Chemical Engineering MCQs with Answers

• A. Sankey diagram
• B. Cox chart
• C. Ostwald chart
• D. None of these

Explanation: A Sankey diagram represents an energy or heat balance by showing input energy and its useful and wasted outputs in proportionate widths.

• A. Conduction
• B. Radiation of heat from the roof of the combustion chamber
• C. Natural convection
• D. None of these

Explanation: In a reverberatory furnace, the flame and hot gases heat the roof, which then radiates heat onto the charge.

• A. 350
• B. 750
• C. 1050
• D. 1250

Explanation: Metallic recuperators are generally limited to about 750°C because oxidation and high-temperature corrosion become severe above this…

• A. Use of non-preheated combustion air
• B. Use of pulverised solid fuels
• C. Use of excessive positive draft in the furnace
• D. Imperfect mixing of fuel & air and infiltration of air

Explanation: Complete combustion would require perfect fuel-air mixing and no air leakage, conditions that are not achieved in practical furnaces.

• A. Muffle furnace
• B. Annealing furnace
• C. Reheating furnace
• D. Rotary kiln

Explanation: An annealing furnace is specifically designed for heat treatment, in which controlled heating and cooling soften the material and relieve…

• A. Resistance
• B. Low frequency induction
• C. Arc
• D. None of these

Explanation: An arc furnace generates heat through an electric arc between electrodes and the charge.

• A. Heat release rate of the fuel
• B. Preheat temperature of fuel & air
• C. All A., B. and C.
• D. Method of mixing the fuel & air

Explanation: The chamber must provide enough volume for the required heat release and residence time, both of which are affected by fuel-air mixing and…

• A. Preheating of cold stock
• B. Preheating of combustion air
• C. Steam generation in waste heat boilers
• D. All A., B. and C.

Explanation: Flue-gas heat can be recovered by heating the stock, preheating combustion air, or producing steam in a waste-heat boiler.

• A. Pot
• B. Induction
• C. Arc
• D. Resistance

Explanation: Arc, induction, and resistance furnaces convert electrical energy into heat.

• A. Permits the use of high ash content coal
• B. Accelerates the burning rate and economises on fuel consumption
• C. Permits the use of low fusion point ash coal
• D. All A., B. and C.

Explanation: Pulverising coal greatly increases its surface area, so combustion is faster and more complete, reducing fuel consumption.

• A. Blast furnace
• B. Steam boiler
• C. Salt bath furnace
• D. Annealing furnace

Explanation: In a salt-bath furnace, the workpiece is immersed in molten salt, which acts as the liquid heat-transfer medium and gives rapid, uniform…

• 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

Explanation: The heat-transfer relation is governed directly by temperatures, area, and surface emissivity, not by whether the fuel is solid, liquid…

• A. Preheating the fuel gas
• B. Increasing the draft in the furnace
• C. Oxygen enrichment of combustion air
• D. Preheating the combustion air

Explanation: Increasing furnace draft usually admits more excess air, which dilutes the fuel gas and lowers the adiabatic flame temperature.

• A. 10-15
• B. 45-50
• C. 25-30
• D. 65-70

Explanation: Lumpy-coal furnaces lose substantial heat through hot flue gases, radiation, incomplete combustion, and furnace-wall losses, so their…

• A. None of these
• B. Open hearth furnace
• C. Coke ovens
• D. Soaking pit

Explanation: A soaking pit can recover heat from outgoing furnace gases to preheat the combustion air, making it a recuperative furnace.

• A. Positive pressure exists in the furnace
• B. The fan operates hot and hence blades are liable to corrosion and erosion
• C. Air is sucked in, so air leaks are more and hence the furnace efficiency is reduced
• D. None of these

Explanation: A forced-draught fan pushes combustion air into the furnace, producing pressure above atmospheric pressure.

• A. Coke oven heating chamber
• B. Both A. and B.
• C. Open hearth furnace
• D. Neither A. nor B.

Explanation: Both coke-oven heating chambers and open-hearth furnaces use regenerative arrangements, storing heat from waste gases and returning it to…

• A. More of CO2 in flue gas
• B. Less of excess air
• C. More of CO in flue gas
• D. More of excess air

Explanation: An oxidising furnace atmosphere requires oxygen in excess of the stoichiometric combustion requirement, so excess air must be increased.

• A. Use of waste heat recovery equipments
• B. Size of the furnace
• C. Emissivity of the refractory walls
• D. Thickness of the stock

Explanation: Heat transfer to the stock is governed by factors such as furnace geometry, refractory emissivity and stock thickness.

• A. Protect the charge from the effects of the products of combustion
• B. Both A. & B.
• C. Smooth out temperature inequalities on the combustion side of the muffle wall
• D. Neither A. nor B.

Explanation: A muffle separates the charge from direct contact with combustion gases and also helps distribute heat more uniformly through its wall.