This set of Energy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Cool and Ash Handling System – 1”.
1. What is the role of breaker house in coal feeding?
a) To break the coal into smaller pieces
b) To separate different sizes of coal
c) To separate the light dust from the coal
d) To powder the coal
Explanation: Because of the brittle nature of the coal, it is a common nature of coal to emit light dust/coal dust during transportation, mining and machine handling. This dust needs to be cleared out and it is performed by coal breaker.
2. When coal is being burnt how much % of ash is formed compared to the whole amount?
Explanation: The coal available in nature already contains some percent of ash and when it is burnt. Due to its brittle nature more amount of ash is produced. And coal is one of the largest types of industrial waste generated. For environmental benefits, this coal ash is reused as a type of by-product in different types of industries.
3. Why is it important to prefer ash handling systems?
a) Coal ash produced destroys the machinery by entering into them
b) Coal ash produced annually accounts for thousands of tones
c) Coal ash can be reutilized for some other purpose
d) Coal ash affects the health of people working at plants
Explanation: Considering the large coal burning capacity plant of modern times, the amount of ash produced when the coal is burnt is in thousands of tones. It could have an effect on other subjects too if the proper ash handling methods are not followed. And for different environmental, economical and product benefits the coal ash is reused by different types of industries in different ways of its necessity.
4. Large amount of coal is transported by ________
b) sea or river ways
c) road transportation
d) by airlifting
Explanation: The railway is preferred since it is quite economical as well as loading and unloading of coal is easy. And at stretch tons of coal can be transported by goods train from one place to another place. Coal is considered as a bulk commodity value which falls in category of minerals and ores. If roadways are preferred only minimal amount of load can be transported. But by railway, long distances with huge amount of coal can transported to any region/part of the country.
5. The coal is fed to the furnace through _________
a) conveyor belt
b) wagon tipper
Explanation: Hopper is the conical shaped slow coal dispenser to the furnace. It is placed right above the furnace and a live feeder mechanism is set at end of hopper for a controlled flow. There is no requirement of any external power/force since this works on gravity force.
6. Which system consumes less power out of all ash handling systems?
a) Mechanical ash handling system
b) Pneumatic ash handling system
c) Hydraulic ash handling system
d) Steam jet ash handling system
Explanation: The mechanical ash handling system consumes less amount of power. Since the power is required by the conveyor belt to transfer the ash from boiler furnace to over head bunker which is located at end of the conveyor belt. And in case of pneumatic there is high power requirement to draw and blow the air at high velocities and high pressures.
7. What is the function of cyclone separators in pneumatic ash handling system?
a) To separate the lighter dust particles
b) To force up the movement of ash through pipes or tubes
c) To draw out the dust from furnace
d) To separate minute coal particles
Explanation: Cyclone separators use air to swirl around the ash that has been dispensed into them. Due to centrifugal action heavier ash settles down, where as lighter dust/ash particles is collected in hopper and dumped out. The air flows in helical pattern which makes easy for the heavier dust particle to settle down easily without interrupting the airflow.
8. Which medium is used to carry ash in the pneumatic ash handling system?
a) Conveyor belt
b) Water trough
d) Chain belt
Explanation: In pneumatic ash handling system, Air is used to carry ash to long distance at a capacity of 5 to 30 tonnes per hour. And the air used for this purpose is easily cleanable and can be exhausted back into atmosphere after the complete filtration processes.
9. Which system is noisy out of all the following ash handling systems?
a) Steam jet ash handling system
b) Mechanical ash handling system
c) Pneumatic ash handling system
d) Hydraulic ash handling system
Explanation: The air is made to pass at very high pressure in order to carry out the ash for long distance. Since the air is moving at high speed at high velocity in the conveying pipes, it tends to create a lot of noise by hitting the walls of pipe at swift turns and curves.
10. Which medium is used to carry ash in hydraulic system?
Explanation: Water is used as the medium to carry ash at high velocity. Depending on water pressure the system is divided as Low pressure system and High pressure system. In low pressure system, sloped sumps are used to move the ash at low velocity and in high pressure system nozzle sprays used to ram up the speed of ash flow.
11. What would be the amount of distance that a low pressure system could carry the ash?
Explanation: Low pressure system moves the ash mixed in water at a distance of 3 to 5 m/s in a sloped pump made of reinforced constituents and this movement is continuous. So, it has the ability to carry the ash for such long distance. There is no requirement any auxiliary source to move the ash mixed with water.
12. What is the capacity of low pressure hydraulic ash handling system?
a) 80 tonnes/hour
b) 22 tonnes/hour
c) 50 tonnes/hour
d) 10 tonnes/hour
Explanation: The capacity of low pressure hydraulic ash handling system is 50tonnes/hour at a speed of 3m/s. Since the ash produced is mixed in water and dumped, the water has the ability to dissolve and intake more amount of ash. And this mixture is spread throughout the sump.
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