Power Plant Engineering Multiple Choice Questions on “Coal-Oil & Coal-Water Mixtures – I”.
1. Which of the following is not considered a type of coal according to ASTM?
a) anthracite
b) bituminous
c) peat
d) lignite
Answer: c
Clarification: Because peat contains 90% of moisture and hence is not suitable as utility fuel.
2. Which of the following is not directly determined in the Proximate Analysis of coal?
a) Volatile Matter
b) Fixed Carbon
c) Moisture
d) Ash
Answer: b
Clarification: Fixed carbon is the difference between 100% and sum of the percentages of volatile matter, moisture and ash.
3. Which of these is not a component of coal in Ultimate Analysis?
a) carbon
b) sulphur
c) ash
d) phosphor
Answer: d
Clarification: This component is not determined in Ultimate Analysis.
4. If M and A represent the percentages of moisture and ash respectively, the dry and ash free analysis in Ultimate Analysis is obtained on dividing other components by the fraction of?
a) {1-(M+A)}/100
b) {1-(M-A)}/100
c) {1-(A-M)}/100
d) 1-{(M+A)/100}
Answer: d
Clarification: The fraction of ash and moisture is given by (M+A)/100. So the dry and ash free part is 1-{(M+A)/100}.
5. The extent of caking in coal is determined using __________
a) swelling index
b) grindability
c) weatherability
d) heating value
Answer: a
Clarification: Swelling index is the quantitative evaluation method devised to determine the extent of calling in coal.
6. Coke devoid of volatile matter is called __________
a) caking coal
b) free-burning coal
c) agglomerate
d) coke
Answer: d
Clarification: Coke is the type of coal devoid of volatile matter.
7. Which of the following property is the inverse of the power required to grind coal to a particular size for burning?
a) heating value
b) weatherabillity
c) grindability
d) sulphur content
Answer: c
Clarification: This property of coal is measured by the standard Grindability Index.
8. The design of steam generator greatly depends on __________
a) spontaneous combustion
b) sulphur content
c) ash softening temperature
d) heating value
Answer: c
Clarification: The ash softening temperature is the temperature at which ash becomes plastic. If the furnace temperature is higher, ash forms molten slag and causes trouble in discharge.
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