chemical engineering fuels and combustion Mcqs
251. A good metallurgical coke should have very low__________________?
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A. Porosity

B. Hardness & strength

C. Fusion point of its ash

D. Sulphur & phosphorous content
252. Coking time in narrow by-product coke ovens is around ______________ hours?
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A. 48

B. 18

C. 80

D. 8

253. Benzene is used__________________?
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A. As a perfume

B. As an explosive

C. As a motor fuel

D. For making insecticides (e.g., DDT, BHC etc.), detergent & rubber (SBR)
254. Low temperature oxidation of coal is accelerated by the____________________?
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A. Storage in large heaps

B. Storage in compressed piles

C. All A., B. and C.

D. Absence of porous or friable particles

255. The weathering index of a coal________________?
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A. Is a measure of its caking tendency

B. Is a measure of its size stability, when stored & exposed to weather

C. Is related to its calorific value

D. Gives an idea of the fusion temperature of ash

256. If oxygen content in the flue gas rises too high, fuel is being wasted by _______________?
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A. None of these

B. Dry gas/stack gas loss

C. Moisture loss

D. Incomplete combustion

257. Width of the coke oven towards coke side is slightly more than that on pusher side to____________________?
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A. None of these

B. Facilitate easy discharging of coke as it swells during carbonisation

C. Facilitate uniform heating of the oven

D. Increase the output of the coke

258. Dry air requirement for burning 1 Nm3 of CO to CO2 may be around _______________ Nm3 ?
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A. 1.75

B. 2.4

C. 11.4

D. 0.87

259. If CO2 is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as___________________?
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A. N2

B. CO

C. O2

D. SO2
260. Main constituents of Benzol are ____________________?
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A. Tar & creosote

B. Anthracene & phenol

C. Ammonia & phenol

D. Benzene, toluene & xylene
261. Ionisation potential applied across the electrodes of electrostatic tar precipitator is around_____________________?
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A. 60 KV AC

B. 230 V AC

C. 60 KV DC

D. 230 V DC

262. Heat penetration rate in narrow coke ovens in high temperature carbonisation of coal is around ______________ cm/hr?
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A. 20

B. 2.5

C. 10

D. 0.5

263. Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300 C to avoid the___________________?
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A. Chances of clinker formation

B. Incomplete combustion of coal

C. Requirement of large volume combustion chamber

D. Risk of explosion
264. Preheating of ______________ the flame temperature?
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A. Either the fuel or the air does not affect

B. Combustion air decreases

C. Either the fuel or the air or both, increases

D. The gaseous fuel before combustion decreases

265. A coal containing high amount of volatile matter will have__________________?
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A. High fusion point of its ash

B. Low adiabatic flame temperature

C. Low ignition temperature

D. Very little ash content

266. Natural draught produced by a chimney depends upon the _____________________?
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A. Density of the chimney gases

B. Height of the chimney

C. Both A. and B.

D. Neither A. nor B.

267. Coke oven gas compared to blast furnace gas is________________?
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A. Lighter

B. Less poisonous

C. More explosive and inflammable

D. All A., B. and C.
268. The maximum adiabatic flame temperature in air as compared to that in pure oxygen is_______________?
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A. Either lower or higher, depends on the type of fuel

B. Much higher

C. Much lower

D. Same

269. Hard coke is manufactured from___________________?
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A. Anthracite

B. Lignite

C. Semi-anthracite

D. Bituminous coal
270. A particular coal is said to be free burning when it __________________?
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A. Burns completely

B. Gives smokeless burning

C. Shows little or no fusing action

D. None of these

271. Volatile matter content of metallurgical coke may be around ______________ percent?
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A. 30-33

B. 15-Oct

C. 1-2

D. 22-26

272. If the specific heat of gaseous products of combustion of a fuel is high, the abiabatic flame temperature will be_____________?
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A. High

B. None of these

C. Low

D. Very high, if the fuel is of low calorific value

273. The lowest temperature, at which a solid fuel produces enough vapors to support continuous combustion, is called ?
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A. Fire point

B. Kindling temperature

C. Burning temperature

D. Smoke point

274. Gross & net calorific value is the same for___________________?
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A. Coke oven gas

B. Blast furnace gas

C. L.D. converter gas

D. None of these

275. _____________ present in coal is not determined in its ultimate analysis ?
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A. Total carbon

B. Nitrogen

C. Hydrogen

D. Fixed carbon
276. A good quality coal should have ___________________?
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A. None of these

B. Low fusion point of ash

C. High ash content

D. High sulphur

277. Which of the following gaseous fuels is likely to have the highest gross calorific value ?
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A. Sewage gas

B. Natural gas

C. LPG

D. Producer gas

278. Coal containing large quantity of _______________ are difficult to wash?
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A. Volatile matter

B. Free impurities

C. Ash

D. Inherent mineral matter
279. (64-132) rank coal (ASTM) means a coal with 64%___________________?
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A. Ash and a heating value of 13, 200 BTU/1b

B. None of these

C. Fixed carbon and a heating value of 132 BTU/1b

D. Fixed carbon and having a heat value of 13, 200 BTU/1b
280. A coal that softens and fuses on heating is_________________?
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A. Classified

B. Caking

C. Non-caking

D. Carbonised

281. High amount of sulphur and phosphorous in coke causes ____________________ ?
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A. Decrease in its calorific value

B. Brittleness of steel made by using it

C. Increase in its strength

D. None of these

282. The temperature at which plastic layer formation takes place during carbonisation of coal varies from ______________ C ?
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A. 350 to 450

B. 700 to 850

C. 550 to 650

D. 100 to 150

283. Fixed carbon in coal is defined as______________________?
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A. The total quantity of carbon present in the coal

B. The one which is present in the residue after combustion

C. That present in volatile matters

D. Hundred minus the percentage of volatile matter, ash and moisture
284. Efficiency of the combustion of a fuel is judged by the ______________ the flue gas?
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A. Temperature of

B. Colour of

C. % of CO2 in

D. % of O2in
285. When incomplete combustion loss is high, the flue gas analysis shows large amount of ________________?
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A. O2

B. CO

C. C

D. CO2

286. Degree of carbonisation of coal during coke making can be roughly judged by the ______________ of the coke produced?
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A. Volatile matter

B. Moisture content

C. Colour

D. Ash content

287. Water gas constitutes mainly of __________________?
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A. CH4 & H2

B. CO & H2

C. CO & N2

D. CO2 & H2

288. Which of the following can be made into briquettes without the use of a binder ?
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A. Anthracite coal

B. Lignite

C. Bituminous coal

D. None of these

289. Gobar gas constitutes mainly of___________________?
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A. CO & CO2

B. CO & N2

C. CH4 & CO2

D. CH4 & N2

290. In Orsats apparatus, ammoniacal cuprous chloride is used for selectivity absorbing________________?
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A. O2

B. CO

C. H2O

D. CO2

291. Low temperature carbonisation of coal takes place at ______________ C?
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A. 300

B. 150

C. 700

D. 1100

292. Furnace oil consumption in a furnace for a given duty employing preheated combination air (at 300) may be reduced by about ______________ percent as compared to the use of atmospheric combustion air?
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A. 5

B. 10

C. 20

D. 35

293. Pick out the wrong statement ?
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A. Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat

B. Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature

C. Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature

D. Adiabatic flame temperatures of actual combustions are always less than the maximum values

294. KOH solution used in Orsat apparatus absorbs____________________?
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A. CO2

B. SO2

C. Both A. & B.

D. Neither A. nor B.

295. The calorific value of natural gas is about ______________ kcal/Nm3?
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A. 25,000

B. 35,000

C. 2,500

D. 10,000
296. Oxygen percentage (by weight) in atmospheric air is_________________?
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A. 23

B. 29

C. 21

D. 19

297. Blast furnace gas constitutes mainly of_________________?
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A. N2 & CO

B. CH4 & CO2

C. N2 & H2

D. N2 & CH4

298. In low temperature carbonisation of coal as compared to high temperature carbonisation _____________ produced is less?
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A. Free carbon content in tar

B. Difference in gross & net calorific value of the coke oven gas

C. Yield of ammonia present in coke oven gas

D. Yield percentage of coke

299. Blast furnace gas is a very poisonous gas because of its predominantly high _______________ content?
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A. H2O

B. CH4

C. CO

D. CO2

300. Main constituent of natural gas is ________________?
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A. H2

B. C2H6

C. C3H8

D. CH4 (upto 90%)