chemical engineering fuels and combustion MCQs – Page 22

Practise multiple-choice questions from chemical engineering fuels and combustion for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering fuels and combustion Mcqs
421. The most matured coal out of the following is__________________?
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A. Bituminous

B. Semi-anthracite

C. Sub-bituminous

D. Lignite

422. For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will_____________________?
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A. Decrease

B. Increase or decrease depending on the fuel type

C. Not change

D. Increase

423. Volumetric ratio of N2 to O2 in dry atmospheric air is ______________?
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A. 4.76

B. 0.21

C. 0.79

D. 3.76
424. Which of the following fuel gases will require maximum amount of air for combustion of 1 Nm3 gas ?
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A. Natural gas

B. Producer gas

C. Water gas

D. Blast furnace gas

425. Air/gas ratio for complete combustion will be the highest for__________________?
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A. Coke oven gas

B. LPG

C. Gobar gas

D. Carburetted water gas

426. Ignition temperature decreases progressively from anthracite to lignite, because___________________?
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A. Ash content increases

B. Moisture content increases

C. Volatile matter content increases

D. Carbon content decreases

427. Pick out the wrong statement ?
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A. Specific gravity of coal increases with its increasing maturity

B. io of coal</strong>

C. Specific heat of coal decreases with increases in the volatile matter and decrease in the C/H

D. Angle of repose of coal increases with its increasing size

E. Refractive index and reflectance of coal increases with the increasing rank of coal

428. Washing of coal _________________?
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A. All A., B. and C.

B. Improves its coking properties

C. Increase the fusion point of its ash by removing chlorine compounds

D. Reduces its ash & sulphur content

429. Which of the following coke has the least percentage of ash ?
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A. Foundry coke

B. Beehive coke

C. Petroleum coke

D. Metallurgical coke

430. Coke compared to the coal from which it has been made, contains ____________________?
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A. All A., B. and C.

B. Less volatile matter

C. Greater percentage of ash

D. More carbon

431. High ash containing coke____________________?
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A. Is desirable in producer gas manufacture

B. Has poor strength and abrasion resistance

C. Produces more slag when used in the blast furnace

D. None of these

432. Highly reactive coke have lower ___________________?
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A. Porosity

B. Coke reactivity index (CRI)

C. Critical air blast (CAB) value

D. Both B. and C.

433. Which of the following is coking ?
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A. Vitrain

B. Fussain

C. Both A. & B.

D. Neither A. nor B.

434. Pensky-Marten apparatus is used for those oils, whose flash points are _____________ F?
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A. < 90

B. > 120

C. 90-110

D. < 120

435. The advantage of firing pulverised coal in the furnace lies in the fact, that it____________________?
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A. Permits the use of high ash content coal

B. All A., B. and C.

C. Permits the use of low fusion point ash coal

D. Accelerates the burning rate and economises on fuel combustion
436. Calorific value of coal middling generated in coal washeries during washing of coal may be around _____________ Kcal/kg?
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A. 8000

B. 1000

C. 6000

D. 4000
437. Which of the following is a rich fuel gas ?
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A. None of these

B. Producer gas

C. Coal gas from underground gasification of coal

D. Refinery gases
438. Pick out the wrong statement ?
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A. ing pulverised fuel

B. None of these

C. Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible

D. l

E. Low grade coal can be used, but generally high volatile matter coals are more suitable for

F. Pulverised fuel can be completely burnt with less percentage of excess air compared to lump

439. Too much of excess air in combustion results in high___________________?
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A. Fuel consumption for the same heat load

B. Percentage of oxygen in flue gases

C. Stack gas temperature

D. All A., B. and C.
440. Combustion of pulverised coal as compared to that of lump coal ________________?
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A. Develops a non-luminous flame

B. Develops a low temperature flame

C. Provides a lower rate of heat release

D. Can be done with less excess air