This set of Energy Engineering Interview Questions and Answers focuses on “Coal and Ash Handling System – 2”.
1. _________ is used in high pressure hydraulic ash handling system, to quench the ash.
a) Turbines
b) Lubricants
c) Water troughs
d) Nozzle sprays
View Answer
Explanation: As we know Nozzles are used to increase pressure. Also, they are also used to quench the ash. The ash falling from the conveyor belt is quenched to make it flow down through the sump. Water trough is used in order to avoid dust creating from falling ash from the furnace.
2. Which of the following ash handling system is more suitable for large thermal plants?
a) Steam jet ash handling system
b) Mechanical ash handling system
c) Pneumatic ash handling system
d) Hydraulic ash handling system
View Answer
Explanation: Hydraulic ash handling system is more suitable large thermal plants since its ash carrying capacity is considerably large. And also it has ability to dissolve the ash in the water which makes its capacity large. It also has lots of advantages it is clean, dust free and no noise is produced. The water used can be recycled only for limited amount of times.
3. What is the important feature of hydraulic ash handling system?
a) It is clean and dustless
b) It can discharge ash for long distances
c) The unhealthy aspect of ordinary ash basement work is eliminated
d) Absence of working parts in contact with ash
View Answer
Explanation: Particularly in hydraulic system the ash is actually quenched in water. So, there is less chance that ash has any possibility of getting in contact with the machineries. There is less chances of machine falling into a repair and maintenance is less as compared to any other type of ash handling system.
4. In hydraulic ash handling system, large quantities of leachate under a positive pressure head in pond pose a constant threat to ________
a) cause pungent smell
b) the livelihood
c) ground water quality
d) the nearby flora
View Answer
Explanation: Since there is constant gravity pressure that is exerting on the surface of the ponds or other water bodies where hydraulic ash is dumped. When the same water is absorbed into the ground, it affects the quality of ground water. This effect indirectly affects growth of plants and degrades the land around water body making it unusable.
5. Which of the following ash handling system is not flexible to re-locate/re-place its discharging site?
a) Steam jet ash handling system
b) Mechanical ash handling system
c) Hydraulic ash handling system
d) Pneumatic ash handling system
View Answer
Explanation: Since the hydraulic ash handling system involves the usage of liquids, the discharging sites cannot be re-located/re-placed. Else constructing/developing a new discharging site is possible but the old one cannot be replaced since it is a wet system. In case of all other forms of ash handling system it is easy since they are dry system and they won’t have much of an impact on the following discharging site/land.
6. ___________ and __________ are the common problems on pipeline inner walls when the slurry contains calcium, magnesium and sulphate ashes.
a) Clogs and Corrosion
b) Scaling and Cracks
c) Pores and Contamination
d) Scaling and Cementation
View Answer
Explanation: Scaling and Cementation are the two main problems caused on the inner walls of pipeline, when there is contamination of calcium, magnesium and sulphate in the discharge. Calcium or magnesium contained mixtures have limited solubility. So, they intend get deposited on the materials.
7. Which of the following ash is suitable for selling?
a) Bed ash
b) Synthetic gypsum
c) Fly ash
d) Clinkers
View Answer
Explanation: Fly ash is sold in the market, which is used in concrete bricks, cement clinkers, road subbase and as mineral filler in asphaltic concrete. Fly ash is very fine in its structure, composed mostly of silica made from burning of coal in the furnace or boiler. And ‘Bed ash’ refers to the ash that’s struck on the walls of boiler which is very coarse in nature.
8. Which ash handling system can be built up in limited space?
a) Mechanical ash handling system
b) Pneumatic ash handling system
c) Hydraulic ash handling system
d) Steam jet ash handling system
View Answer
Explanation: Steam jet ash handling system can be constructed particularly when there is a limited amount of space is available because not much amount of space is required for its setup and operation. Pneumatic and hydraulic ash handling system require huge amount of space for their construction and operation. Steam jet ash handling system is used in small capacity plants.
9. In what form does the total ash produced in the furnace escapes through the chimney?
a) Fines
b) Aerosols
c) Gas
d) Cinder
View Answer
Explanation: Fines are the particles which vary in the size of 1 to 80 microns. These could easily get escaped into air via chimneys. About 80% of ash produce is in this range of microns and everything gets easily escaped into air and the rest is made use for other possible purposes.
10. What is the capacity of the steam jet ash handling system?
a) 45tonnes/hour
b) 15tonnes/hour
c) 30tonnes/hour
d) 150tonnes/hour
View Answer
Explanation: The capacity of the steam jet ash handling system is limited 15tonnes/hour since the plant built up is in less space. And it has ability to remove ash through a horizontal distance of 200m. the operation of this system is noisy since steam jet of high velocity is produced in such a limited place.
11. What material is used in pipe linings for linking of steam jet system?
a) Nickel alloy
b) Graphite
c) Titanium
d) Copper alloy
View Answer
Explanation: The abrasive particles present in ash cause wear and tear in pipes due to high speed movement in pipes of steam jet system. Even chilled iron also can be used to line the pipes to overcome the following problem. And also avoiding bends and turns in pipes would reduce the damage of pipes.
12. What is the distance up to which steam jet ash handling system is capable of removing ashes?
a) 200m
b) 50m
c) 75m
d) 350m
View Answer
Explanation: Even though the size of the steam jet ash handling capacity is compact, the high velocity steam jet can easily remove the ashes up to 200m. Since it is small sized plant its capability to remove ashes is limited. The moisture of steam also makes the ash wet and it would gain a light amount of weight which becomes a bit difficult to move ash at a longer distances.
13. What measure to be taken to avoid the noise produced in the pneumatic ash handling system?
a) Passing ash at slower pace
b) Reducing swift turns and sharp bends
c) Broadening of pipe width
d) Reducing and crushing the size of the ash
View Answer
Explanation: The air and ash mixture moving through the pipe at high pressure tends to hit the walls at inner side of pipe when there are number of swift turns and sharp bends made. Avoiding them can reduce the noise up to 50%.
14. Is there any requirement of auxiliary steam producer in the steam jet ash handling system.
a) True
b) False
View Answer
Explanation: There is no requirement for any auxiliary steam producing unit since the steam required is drawn from the boiler present in the system. The steam drawn from the boiler is pressurized and then utilized. Non-requirement of auxiliary unit is advantageous as it would cut slack in the expenses of setting up the plant.
15. How much amount of steam is required to remove 1 ton of ash from the steam jet ash handling system?
a) 100kg
b) 450kg
c) 65kg
d) 200kg
View Answer
Explanation: 100 kg of steam is required to remove 1 ton of ash. Since the steam let out is at very high velocity, 1 ton of ash can be easily moved to compare and balancing to its weight ratio. And this wholesome amount of steam is generated by the boiler present in the plant.
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