Chemical Engineering Calculations Flashcards by Yssa Siuagan

In a flue gas analysis by Orsat’s apparatus, carbon monoxide is absorbed by

A. Cuprous chloride
B. Potassium hydroxide
C. Alkaline pyrogallol solution
D. None of these

A. Cuprous chloride

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Calorific value as determined by bomb calorimeter is

A. Higher calorific value at constant volume
B. Gross calorific value at constant pressure
C. Lower calorific value at constant pressure
D. Net calorific value at constant volume

A. Higher calorific value at constant volume

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Incomplete combustion by fuel is characterized by

A. Smoke formation
B. High gas temperature
C. High percentage of oxygen in flue gas
D. High carbon monoxide content in flue gas

D. High carbon monoxide content in flue gas

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For maximum discharge through a chimney, its height should be

A. 200 meters
B. Infinitely long
C. More than 105.7 meters
D. Equal to the height of the hot gas column producing draught

D. Equal to the height of the hot gas column producing draught

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Oxygen percentage (by weight) in atmospheric air is

A. 19
B. 21
C. 23
D. 29

C. 23

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Stack (chimney) height in a big thermal power plant ks dictated by

A. Pollution control aspect
B. Draught to be created
C. Limitation of constructional facilities
D. None of these

B. Draught to be created

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A particular coal is said to be free burning when it

A. Burns completely
B. Gives smokeless burning
C. Shows little or no fusing action
D. None of these

C. Shows little or no fusing action

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As time passes, the calorific value of stored coal

A. Decreases
B. Increases
C. Remains unaltered
D. May increase or decrease (depends on the method of storage)

A. Decreases

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Emission of dense white smoke out of chimney of a thermal power plant is an indication of the use of

A. Less air for combustion
B. Correct amount of air for combustion
C. Too much air for combustion
D. Pulverized coal in boilers

C. Too much air for combustion

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Use of pulverized coal in boiler furnace provides

A. High calorific value
B. Better combustion
C. Smokeless burning
D. Pulverized coal

B. Better combustion

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Which of the following fuels is best for burning on chain grate smoker?

A. Non caking coal
B. Caking coal
C. Coking coal
D. Pulverized coal

A. Non caking coal

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Which of the following accounts for maximum energy loss in a boiler?

A. Flue gases
B. Ash content in the fuel
C. Incomplete combustion
D. Unburnt carbon in flue gases

A. Flue gases

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“Over-fire burning” in a furnace is a phenomenon characterized by

A. Supply of excess fuel
B. Supply of excess air
C. Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air
D. None of these

C. Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air

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When steam is passed over coal resulting in the endothermic reaction (C + H2O → CO + H2), it is called

A. Carbonization of coal
B. Oxidation of coal
C. Coalification
D. Gasification of coal

D. Gasification of coal

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Fischer-Tropsch methid aims at

A. Gasification of coal
B. Synthesis of gasoline (from water gas)
C. Hydrogenation of coal to produce gasoline
D. None of these

B. Synthesis of gasoline (from water gas)

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Commercial production of petrol from coal (as practiced in a factory at Sasol in South Africa) is done by

A. Hydrogenation of coal
B. Gasification of coal
C. Carbonization of coal
D. None of these

A. Hydrogenation of coal

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In case pulverized coal from steam boiler, the secondary air serves the main purpose of

A. Transportation of coal
B. Drying of coal
C. Combustion of coal by supplying in the burner
D. Pre-heating the primary air

C. Combustion of coal by supplying in the burner

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The main function of primary air in pulverized coal fired burner is to

A. Burn CO to CO2
B. Dry transport of the coal
C. Have proper combustion by supplying it around the burner
D. Pre-heat the tertiary air used for complete combustion of CO to CO2

B. Dry transport of the coal

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The advantage of firing pulverized coal in the furnace lies in the fact that it

A. Eprmits the use of high ash content of coal
B. Permits the use of low fusion point ash coal
C. Accelerates the burning rate and economizes on fuel combustion
D. All of the above

C. Accelerates the burning rate and economizes on fuel combustion

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Orsat apparatus is meant for

A. Gravimetric analysis of flue gas
B. Finding out combustion efficiency
C. Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride
D. None of these

D. None of these

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Pick out the wrong statement

A. Theoretical flame temperature is temperature attained by the products of combustion when the fuel is burned without the loss or gain of heat
B. Burning 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 maximum values

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

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The maximum adiabatic flame temperature in air compared to that in pure oxygen is

A. Much lower
B. Much higher
C. Same
D. Either lower or higher, depends on the type of fuel

A. Much lower

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Adiabatic flame temperature of a fuel is dependent on the initial temperature of

A. The fuel
B. The air
C. Both fuel and air
D. Neither fuel nor air

C. Both fuel and air

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Pre-heating of

A. The gaseous fuel before combustion decreases the flame temperature
B. Combustion air decreases the flame temperature
C. Either the fuel or the air ot both increases the flame temperature
D. Either the fuel or the air does not affect the flame temperature

C. Either the fuel or the air ot both increases the flame temperature

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The fuel ratio of the coal is A. Thr ratio of its percentage of fixed carbon to that of volatile matter B. Helpful in estimation of its rank C. Both a and b D. Neither a nor b

C. Both a and b

A fuel containing carbon and carbon monoxide (but containing the hydrogen or its compounds) is burnt in pure oxygen at constant pressure. Its gross calorific value as compared to the net calorific value will be A. More B. Less C. Same D. Data insufficient, can't be predicted

C. Same

Removal of hydrogen from coke oven gas A. Increases its calorific value B. Decreases its calorific value C. Does not alter its calorific value D. Is not possible on commercial scale

A. Increases its calorific value

With increase in calorific value of fuels, their adiabatic flame temperatures A. Increase B. Decrease C. Remain unchanged D. May increase or decrease; depends on the quantity of products of combustion

D. May increase or decrease; depends on the quantity of products of combustion

Grindability index of a coal is 100. It implies that the A. Coal can be pulverized with great difficulty B. Coal can't be pulverized C. Coal can easily be pulverized D. Power consumption in grinding the coal will be very high

C. Coal can easily be pulverized

If the specific heat of gaseous products of combustion of a fuel is high, the adiabatic flame temperature will be A. Low B. High C. Very high if the fuel is of low calorific value D. None of these

A. Low

Calorific value (kcal/kg) of dry wood may be around A. 5 B. 50 C. 500 D. 5000

A. 5

A coal containing high amount of volatile matter will have A. Low ignition temperature B. Very little content C. High fusion point of its ash D. Low adiabatic flame temperature

A. Low ignition temperature

Steam is intermittently admitted in to the fuel bed during the production of producer gas to A. Convert CO to CO2 B. Increase in combustion rate C. Increase the gas production rate D. Minimize the chances of clinker formation

D. Minimize the chances of clinker formation

Which of the following is called "blue gas"? A. Coke oven gas B. Water gas C. Natural gas D. Producer gas (producer using Kopper Totzek gasifier)

B. Water gas

During combustion of gaseous fuel, deficiency of air A. Lengthens the flame B. Tends to shorten the flame C. Does not affect the flame length D. Increases the flame temperature

A. Lengthens the flame

Use of excess of combustion air in the combustion of fuels results in A. Heat losses B. Long flame C. Condensation of water vapor from the flue gas D. None of these

A. Heat losses

A gaseous fuel in order to develop luminosity omn burning, must contain A. Carbon monoxide B. Hydrocarbons C. Hydrogen D. Oxygen

B. Hydrocarbons

Pre-heating of gaseous fuel results in increased A. Flame length B. Flame temperature C. Quantum of flue gas D. Ignition temperature

B. Flame temperature

Quantity of coke oven gas produced by high temperature carbonization of one ton of dry coal may be around A. 30 Nm³ B. 300 Nm³ C. 3000 Nm³ D. 30,000 Nm³

B. 300 Nm³

Coke oven gas is a better fuel than blast furnace gas because of its higher A. Calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity) B. Adiabatic flame temperature C. Heat release rate (thus requiring smaller combustion chamber) D. All of the above

D. All of the above

Which of the following constituents of fuel does not contribute to its calorific value on combustion? A. Hydrogen B. Sulfur C. Carbon D. None of these

D. None of these

Combustion of pulverized coal as compared to that of lump coal A. Develops a non-luminous flame B. Develops a low temperature C. Can be done with less excess air D. Provides a lower rate of heat release

C. Can be done with less excess air

Which of the following is the most important deterrents to an extended use of pulverized coal in boiler firing? A. Ash disposal problem B. Excessive fly-ash discharge from the stack C. High power consumption in its transportation D. Erosion of induced draft fan blades

A. Ash disposal problem

Pulverized coal used in boiler firing have A. Less moisture content B. High fusion point of its ash C. High bulk density D. Lower ash constant

B. High fusion point of its ash

Dry air required to burn one lb of carbon completely may be around A. 11.5 lb B. 2.67 lb C. 16 lb D. None of these

A. 11.5 lb

Dry air requirement for burning 1 ft³ of CO to CO2 may be around A. 2.4 ft³ B. 1.75 ft³ C. 0.87 ft³ D. 11.4 ft³

A. 2.4 ft³

Washing of coal A. Reduces is sulfur and ash content B. Controls its ash fusibility and increases its calorific value C. Improves its coking properties D. All of the above

D. All of the above

Which of the following has the highest gross calorific value? A. Blast furnace gas B. Coke oven gas C. Carburetted water gas D. Oil refinery gas

D. Oil refinery gas

Most of coking coals are A. Anthracite coal B. Bituminous coal C. Lignite D. None of these

B. Bituminous coal

High excess air in combustion of fuels results in A. Increased fuel consumption B. Incomplete combustion C. Smoky flame D. None of these

A. Increased fuel consumption

Atomizing steam to fuel oil ratio in a burner should be around A. 0.5 B. 2 C. 3 D. 5

A. 0.5

For every 10% increase in the excess air; the fuel consumption increases by A. 0.1% B. 2% C. 5% D. 10%

A. 0.1%

Ash content in the coke produced from a coking coal having 20% ash may be around A. 5% B. 2% C. 17% D. 25%

D. 25%

Out of the following fuels, the difference between the net and gross calorific value is maximum in case of A. Pitch B. Fuel oil C. Blast furnace gas D. Bituminous gas

B. Fuel oil

Spontaneous combustion of coal on storage results to A. Inadequate ventilation B. Low temperature oxidation C. Storage in large heaps with small surface to volume ratio D. All of the above

D. All of the above

Efficient burning of anthracite coal requires A. Low preheat of air B. Fine grinding C. High excess air D. All of the above

B. Fine grinding

Low temperature oxidation of coal resulting from bad storage conditions does not decrease its A. Caking power B. Calorific value C. Hydrogen content D. Oxygen content

D. Oxygen content

Rate of temperature oxidation of coal due to bad storage conditions A. Decrease with increase in surface area B. Does not vary with increase in surface area C. Is more for low volatile coal compared to high volatile coal D. Is accelerated by storage in large heaps with small surface to volume ratio

D. Is accelerated by storage in large heaps with small surface to volume ratio

Fusion of point coal asg increases in its A. Iron sulfate content B. Iron silicate content C. Lime and magnesia content D. All of the above

D. All of the above

Which of the following accentuates clinkering trouble on furnace grate burning coal? A. Low density of carbonized residue containing high proportions of iron and sulfur B. Low forced draught and fuel bed temperature C. Thick fire and preheated primary air D. All of the above

D. All of the above

A coal having a high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon A. Is less liable to spontaneous combustion on storage B. Is more difficult to ignite and produces a shorter flame C. Requires smaller combustion space and less secondary air D. None of these

D. None of these

Which of the following can be made into briquettes without the use of a binder? A. Lignite B. Bituminous coal C. Anthracite coal D. None of these

A. Lignite

Presence of free moisture in coal is most disadvantageous during A. Its pulverized (as it requires more power) B. Combustion of fine slacks on the grates C. Handling (e.g. when emptying wagons) D. None of these

A. Its pulverized (as it requires more power)

Which of the following is not a binder for coal briquetting? A. Coal tar B. Bitumen C. Molasses D. None of these

D. None of these

High caking coals A. Produce weak coke B. Produce strong coke C. May damage the coke oven walls during carbonization D. Both b and c

D. Both b and c

Presence of free moisture in coal during its high temperature carbonization A. Reduces the coking time B. Protexts the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls C. Increases the loss of fine coal dust from the ovens when charging D. None of these

B. Protexts the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls

Higher percentage of ash in coal meant for the production of metallurgical grade coke A. Increases the hardness of coke B. Increases the abrasion resistance of coke C. Causes brittleness in steel D. None of these

D. None of these

Increases in ash content of blast furnace coke A. Reduces its consumption in the furnace B. Increases its consumption in the furnace C. Does not affect its consumption in the furnace D. Decreases its hardness and abrasion resistance

B. Increases its consumption in the furnace

High sulfur content in a fuel A. Increases the dew point of the flue gases B. Decreases the dew point of the flue gases C. Reduces combustion efficiency by limiting the permissible temperature reduction of the flue gases D. Both a and c

D. Both a and c

With the increase in carbonization temperature A. Gas yield increases B. Tar yield increases C. Hydrogen percentage in the coke oven gas decreases D. Methane percentage in the coke oven gas increases

A. Gas yield increases

With increase in time of carbonization at a particular temperature (say 1000°C), the ____ percentage in coke oven gas increases A. Hydrogen B. Methane C. Unsaturates D. All of the above

A. Hydrogen

Producer gas containing least amount of tar is produced by A. Partial combustion of coal B. Partial combustion of large size (<50mm) C. High pressure gasification of coal (e.g. in Lurgi gasifier) D. Atmospheric pressure gasification of coal (e.g. in Kopper-Totzek gasifier)

B. Partial combustion of large size (<50mm)

High temperature in gasification of coal favors A. High production of CO2 B. Low production of CO2 C. High production of CO D. Both b and c

D. Both b and c

Lurgi gasifier (high pressure gasifier) as compared to Kopper-Totzek gasifier (atmospheric pressure gasifier) produces A. Higher amount of methane B. Lower amount of hydrogen C. Both a and b D. Higher amount of both methane and hydrogen gas

C. Both a and b

Which of the following constituents of coal is most important in the production of coke? A. Moisture B. Ash C. Volatiles D. Carbon

D. Carbon

Which of the following is most reactive (as regards the formation of CO + H2 from C + H2O)? A. Blast furnace coke B. Low temperature coke C. Anthracite coal D. Sub-bituminous coal

B. Low temperature coke

A coal that softens and fuses on heating in A. Classified B. Carbonized C. Caking D. Non-caking

C. Caking

Purity of coke means that it is high in carbon and low in A. Volatiles B. Ash C. Iron D. Moisture

A. Volatiles

Calorific value (kcal/Nm³) of coke oven furnace gas is around A. 900 B. 4500 C. 7500 D. 2000

B. 4500

Calorific value (kcal/Nm³) of blast furnace gas is around A. 900 B. 4500 C. 7500 D. 2000

A. 900

Blast furnace is a very poisonous gas because of its predominantly high A. H2S content B. CO2 content C. CO content D. CH4 content

C. CO content

Percentage of carbon monoxide in blast furnace gas may be around A. 0.5 B. 5 C. 20 D. 55

C. 20

Percentage of hydrogen in coke oven gas may be around A. 1 B. 5 C. 20 D. 50

D. 50

Percentage of methane in coke oven gas may be around A. 1 B. 10 C. 25 D. 55

C. 25

Coke oven gas compared to blast furnace gas is A. More explosive and inflammable B. Less poisonous C. Higher D. All of the above

D. All of the above

Which of the following gases will require maximum amount of air for combustion of 1 Nm³ gas? A. Blast furnace gas B. Natural gas C. Producer gas D. Water gas

B. Natural gas

Which of the following will generate maximum volume of product of complete combustion (Nm³/Nm³ of fuel)? A. Carburetted water gas B. Blast furnace gas C. Natural gas D. Producer gas

A. Carburetted water gas

Which is the heaviest fuel gas out of the following? A. Blast furnace gas B. Coke oven gas C. Water gas D. Carburetted water gas

A. Blast furnace gas

Fuel can ve defined as a substance which produces heat by A. Combustion B. Nuclear fission C. Nuclear fusion D. All of the above

D. All of the above

Catalyst used in Fisher-Tropsch process is A. Nickel B. Zinc oxide C. Alumina D. Thorium oxide

A. Nickel

In the flue gas analysis by Orsat's apparatus, oxygen is absorbed by A. Potassium hydroxide B. Cuprous chloride C. Alkaline pyrogallol solution D. None of these

C. Alkaline pyrogallol solution

In the flue gas analysis by Orsat's apparatus, carbon dioxide is absorbed by A. Potassium hydroxide B. Cuprous chloride C. Alkaline pyrogallol solution D. Dilute potassium chloride

A. Potassium hydroxide

The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively A. CO2, O2, CO B. CO, O2, CO2 C. CO2, CO, O2 D. O2, CO2, CO

A. CO2, O2, CO

Which of the following has the highest calorific value? A. Lignite B. Sub-bituminous coal C. Anthracite D. Peat

C. Anthracite

The main product of high temperature carbonization is A. Coke B. Ammonia C. Tar D. Coke oven gas

A. Coke

High temperature carbonization produces A. Inferior coke compared to low temperature carbonization B. Less gases compared to liquid products C. Large quantity of tar compared to low temperature carbonization D. None of these

D. None of these

High temperature carbonization takes place at A. 2000°C B. 600°C C. 1100°C D. 1600°C

C. 1100°C

Low temperature carbonization takes place at A. 300°C B. 1100°C C. 500-650°C D. 150°C

C. 500-650°C

Proximate analysis of coal determines A. Moisture, ash, sulfur, volatile matter B. Moisture, volatile matter, ash, fixed carbon C. Moisture, sulfur, nitrogen, fixed carbon D. None of these

B. Moisture, volatile matter, ash, fixed carbon

Ultimate analysis of coal determines A. Carbon, hydrogen, nitrogen, sulfur B. Carbon, ash, sulfur, nitrogen C. Carbon, sulfur, volatile matter, ash D. Carbon, volatile matter, ash, moisture

A. Carbon, hydrogen, nitrogen, sulfur