importance of coal handling system, necessity and requirement of coal handling system, various transportation means, methods and equipment's, advantages and disadvantages of various methods, coal unloading videos.
2. NECESSITY OF COAL HANDLING SYSTEM
A 600MW Power Plant handles about 7200 tons of coals per
day.
Coal handlings are to be flexible, reliable & capable of
handling large quantities in less time than even before.
Coal plays a vital role in electricity generation worldwide.
Coal-fired power plants currently fuel 41% of global
electricity.
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3. REQUIREMENT OF GOOD COAL HANDLING
PLANT
It should have minimum maintenance
It should be simple.
It should be reliable
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4. COAL HANDLING SYSTEM
Coal Delivery
Unloading
Transfer
Outdoor Storage
Covered Storage
Inplant Handling
Weighing
Furnace Firing
Preparation / Weighing
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5. OUT-PLANT HANDLING.(COAL DELIVERY)
Out plant handling means transfer of Coal from mine or
port to storage of coal at plant site.
1. Transportation by Rail: 4000 to 13000 tons/trip.
2. Transportation by Ships: 45 million tons/year.
3. Transportation by Roads: Trucks etc.
4. Transportation by belt & conveyors.
5. Transportation of Coal by Pipe line.
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6. FACTS
Daqin Railway coal trains—20,000 t, 3.2 km, 210
wagons(China).
The longest train there was recorded in 1986, carrying
Kuzbass coal in 439 cars, for the train length of 6500
meters and total weight of 43,500 tonnes (Russia).
one litre of fuel moves 24 ton/km on road, 85 ton/km on
rail and 105 ton/km on water.
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7. UNLOAD OF COAL AT SITE
Unload from Rail cars
Unloading from Ships
1. Unloading equipment.
2. Self unloading ship.
o Unloading from trucks (lifting trucks)
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8. RAIL CAR UNLOADING
Rail car unloading featuring
bottom dump by unloading
bridge.
Rail car unloading
by means of Rotary
Drum
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11. TRANSPORTATION THROUGH ROPE & BELT
CONVEYORS
Transfer of coal by rope, belt & conveyor is also used if
the distance between the mines & power station is less
than 10 km
Conveying capacity was 600 tonnes per hour. The line
was 270 meters long, with a vertical rise of 23 meters. It
eliminated 115,000 truck journeys.
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12. COAL WEIGHING
All of our train weighing systems involves "Load Cell"
technology which is the only genuinely recognized
method of long term accurate & reliable train weighing &
uses the exact principal as weighbridges, truck scales &
every other general scale is based upon.(onboard coal
weighing)
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13. COAL STORAGE
Storage of coal is undesirable because it costs more as
there is,
Risk of spontaneous combustion.
Weathering.
Possibility of loss deterioration during storage.
Interest on capital cost of coal lying dormant.
Cost of protecting the stored coal from deteriorating & so
on.
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14. PURPOSE OF STORAGE OF COAL
To store the coal for a period of 30 – 80 days so that
plant is never required to be shut-down.
Storage of coal allows the purchaser to take the
advantage of seasonal market fluctuation in prices of
coal.
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15. OUTDOOR STORAGE (DEAD STORAGE)
The coal is usually kept on ground in the form of pile
exposed to outside weather.
The coal is required to be protected from deterioration &
weathering
This is a long term storage i.e. 10% of annual
consumption.
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16. CLOSED OR LIVE STORAGE
In the closed or live storage the coal is stored for one or
two days requirement of the power plant.
This storage is used for the purpose of supplying the coal
to the combustion equipment with negligible handling
The coal is usually stored in the vertical cylinder bunkers
or coal bins.
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17. INPLANT COAL HANDLING
The In-Plant coal handling
system deals with feeding of
coal from live storage to the
furnace.
It includes various equipment's
for transfer of coal like belt
conveyor, screw conveyor etc.
& the equipment needed to
weigh the quantity of coal for
feed.
In case of pulverized coal firing
system, it requires large no. of
equipment’s like chutes,
pulverized mills, feeders,
weighing machine, hoppers &
automatic scales.
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18. POINTS TO REMEMBER.
Simple & sound, requiring minimum operations &
transportation.
No double handling of coal in plant.
Handling unit should be centralized to facilitate inspection
& maintenance.
Electric motors can be used as driver of mechanism.
Working parts should be enclosed to avoid abrasion &
corrosion.
System should be able to supply required quantity of coal
as per demand.
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20. CRUSHING OF COAL
Crushers are used to reduce the coal to optimum size.
It is crushed into pieces of 25-30mm for stoker firing and
10-20mm for pulverized coal firing.
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21. VIBRATING SEPARATOR
Size of vibrating separator is fitted after crusher to
screen the coal crushed below set size.
Oversized coal is returned to crusher for further proper
crushing.
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22. TRANSFER OF COAL.
Different equipment’s of coal transfer.
1. Belt conveyors.
2. Screw conveyors.
3. Bucket elevators.
4. Grab bucket elevators.
5. Flight conveyors or scrapers.
6. Skip hoist.
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23. BELT CONVEYORS
It consist of endless belt of suitable material running over
pair of end drums supported at regular interval by series
of rollers(idler).
Max Inclination: 20degree.
Running Speed: 400-500 RPM.
Transport Capacity: 50-100ton/hour over long distance
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24. BELT CONVEYORS (CONT.)
Advantages
1. Low cost & power consumption.
2. Smooth & clean operation.
3. Cheap maintenance.
4. Controlled rate of coal transfer.
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25. SCREW CONVEYORS
It is used for shorter distance(30m).
Totally enclosed from atmosphere.
Coal dust can also be transferred easily.
Diameter: 15-50cm.
Speed: 70-120 rpm.
Transfer Capacity: 100tons/hour.
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26. SCREW CONVEYORS
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Advantages
1. Cheap
2. Requires small space, simple & tight.
3. Dust tight.
Disadvantages
1. High power consumption per ton of coal transfer
2. Wear and tear of screw is high. Shorter life
27. BUCKET ELEVATOR
Coal is lifted vertical or
near vertical direction.
It carries the buckets
fixed to a chain.
Buckets are loaded
with coal at bottom &
discharges at the top.
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Limitation:
The lift of coal is limited to about 30m.
Inclination is limited to 60 degree with horizontal
Transfer Capacity: 60 tons/hour.
28. GRAB BUCKET ELEVATOR
It lifts & transfer coal on a single rail or track from
one point to the other.
It can be used with crane or tower.
Transfer Capacity: 50 tons/hour
Advantages:
1. Requires less power for operation and minimum
maintenance.
2. Used when other arrangements are not possible.
3. Lesser operating cost.
Disadvantages:
1. Initial cost is high.
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29. FLIGHT CONVEYOR OR SCRAPERS
It is generally used for transfer of coal when filling of no.
of storage bin under the conveyor is required.
The coal is discharged in the bottom of trough.
Transfer Capacity: 10-100 tons/hour.
Advantage:
1. Low capital cost.
2. It can transfer both coal & ash.
3. It can vary easily the rate of coal discharge.
o Disadvantages:
1. High energy consumption & maintenance cost.
2. High wear and tear due to dragging action.
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