chemical engineering fuels and combustion Mcqs
451. During coal carbonisation process, the conversion of semi-coke to coke is accompanied by an increase in the _______________ of the mass?
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A. Electrical resistivity

B. Porosity

C. Density

D. None of these

452. Higher percentage of ash in coal meant for the production of metallurgical grade coke ___________________?
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A. None of these

B. Decreases the abrasion resistance of coke

C. Decreases the hardness of coke

D. Causes brittleness in steel

453. Safe condition for storage of high V.M. bituminous coal is that ___________________?
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A. Height of the coal heap should be < 3 metres

B. Maximum 200 tons should be stored in a heap

C. Both A. and B.

D. Neither A. nor B.

454. Yield of coke oven gas in low temperature carbonisation of coal is about ______________ Nm3 /ton of dry coal?
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A. 750

B. 500

C. 60

D. 160
455. The combustion reaction, C + O2 = CO2, is ___________________?
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A. Autocatalytic

B. None of these

C. Endothermic

D. Exothermic
456. Pick out the wrong statement ?
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A. Maximum yield of naphthalene is obtained on distillation of crude oil

B. called its flash point</strong>

C. LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of

D. Each ton of petroleum oil on distillation produces about 30-50 Nm3 of gas

E. als

F. The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn,
457. A coal containing very high percentage of durain is called ______________ coal?
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A. Splint

B. Non-banded

C. Bright

D. Boghead

458. Fussain _____________________?
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A. coal

B. Is friable, charcoal like substance

C. Is non-coking, but when blended with highly coking coal, controls its swelling and produces

D. All A., B. and C.

E. h strength coke on carbonisation

F. Has highest fixed carbon and lowest volatile matter content of all the four banded components

459. By-products are _____________ recovered in Beehive ovens ?
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A. Partially

B. Negligibly

C. Fully

D. Not at all
460. Blast furnace gas burns with a bluish flame, because of the presence of____________________?
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A. CO

B. S

C. CH4

D. CO2

461. Commercial production of petrol from coal (as practised in a factory at Sasol in South Africa) is done by the ________________ of coal?
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A. Gasification

B. None of these

C. Hydrogenation

D. Carbonisation

462. Mineral matter, M and ash percentage A in coal are roughly related as_______________?
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A. M = A

B. M = 0.5 A

C. M = 1.8 A

D. M = 1.1 A
463. Calorific value of pitch creosote mixture (PCM) i.e., C.T.F.-200 is about________________?
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A. 8800 kcal/m3

B. Same as that of coal middling

C. 25000 kcal/kg

D. 8800 kcal/kg
464. Coal is heated in presence of air to a temperature of about _______________ C, while determining its ash content for proximate analysis?
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A. 950

B. 500

C. 750

D. 1100

465. Pick the odd man out?
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A. Oil gas

B. Briquettes

C. Pitch creosote mixture

D. Wood
466. Orsat apparatus is meant for ___________________?
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A. Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride

B. None of these

C. Finding out combustion efficiency

D. Gravimetric analysis of flue gas

467. Flue gas from the heating chamber of by product coke ovens is removed by________________?
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A. Forced draft fan

B. Induced draft fan

C. Natural draft

D. Steam ejector

468. Which of the following constituents of coal is the most important in the production of coke ?
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A. Carbon

B. Moisture

C. Ash

D. Volatiles

469. Which of the following gaseous fuels has the lowest calorific value ?
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A. Gobar gas

B. Blast furnace gas

C. Refinery gas

D. Converter gas

470. Anthracite coal ____________________?
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A. Ignites more easily than bituminous coal

B. Is essentially a coking coal

C. Contains more volatile matter than bituminous coal

D. Burns with short, bluish, yellow-tipped flame producing very little smoke
471. Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is _______________ percent?
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A. In between 37 & 71%

B. None of these

C. 71%

472. Temperature of coke oven gas just before entering into saturator (for recovery of NH3) is about ______________ C?
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A. 30

B. 180

C. 65

D. 120

473. Stack heat losses can be minimised by________________?
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A. Oxygen enrichment of combustion air

B. Controlling the excess air

C. Using low c.v. fuels

D. Maintaining proper draft in the furnace

474. Gross and net calorific value of a fuel will be the same__________________?
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A. If its ash content is zero

B. If its hydrogen/hydrogen compound content is zero

C. If its carbon content is very low

D. Under no circumstances

475. Carbon Content by weight in air dried wood may be about _______________ percent?
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A. 80

B. 10

C. 50

D. 25

476. Pick out the wrong statement ?
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A. Ash is normally removed as fly-ash in Kopper-Totzek process of coal gasification

B. The calorific value (kcal/Nm3) of coke oven gas reduces on removal of hydrogen from it by

C. Percentage of ash in coke produced from medium coking coal is more than that in coal

D. Coal based fertiliser plants in India at Talcher (Orissa) and Ramagundam (A.P) employ

E. ogenic method

F. per-Totzek process of coal gasification

477. Beehive coke oven________________?
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A. Takes 2-3 days for coking of coal but requires no external fuel for heating

B. Produces coke with very poor strength

C. Gives larger yield of coke (around 85%) as compared to by-product ovens

D. Facilitates by-products recovery

478. Fuel gases containing hydrocarbons (e.g. coke oven gas) are not preheated before burning, mainly because __________________?
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A. It reduces its calorific value tremendously

B. There are chances of explosion during preheating

C. The hydrocarbons crack thereby choking and fouling the heat transfer surface by carbon soot

D. It reduces its flame temperature tremendously

479. Eschka mixture, which is used for the determination of sulphur in coal, is a mixture of _____________________?
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A. MgO & Na2CO3

B. MgCO3 & NaCl

C. BaSO4 & NaCl

D. MgSO4 & BaCl2

480. Method of maintaining fires in furnace during standby periods without undue consumption of fuel is called_________________?
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A. Under pressurising

B. Back draughting

C. Banking

D. None of these

481. Calorific value of dry wood may be around ______________ Kcal/kg?
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A. 500

B. 5000

C. 50

D. 5
482. White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is_______?
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A. Pulverised coke

B. Coke Oven Gas

C. Tar

D. Sulphide Coke

483. Quantity of coke produced from metallurgical coal may be around _____________ percent?
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A. 50

B. 30

C. 75

D. 95

484. Pick out the wrong statement ?
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A. Coals are divided in four species according to their carbon content in Seylors classification

B. Carburetted water gas is also called blue gas

C. Carbonisation time in a by-product coke oven is about 16 hours

D. Gross and net calorific value of a fuel is the same, if it does not contain hydrogen or

E. rocarbons

485. Which of the following has the least calorific value (kcal/Nm3) ?
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A. Blast furnace gas

B. Sewage gas

C. Coke oven gas

D. Natural gas

486. Calorific value of bituminous coal may be around ______________ Kcal/kg?
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A. 1500

B. 20000

C. 500

D. 6500