Carbonisation of coal

This is full description of carbonisation of coal

1. GOVERNMENT ENGINEERING COLLEGE,

GANDHINAGAR,SECTOR-28
Metallurgy department Prepared by:-
Subject :-FFRP Sarvaiya Riddhiben P.
Topic:-Carbonisation of coal

2. WHAT IS CARBONISATION?
•Heating of coal in absence of air to
produce coke is called its carbonisation or
destructive distillation.
•By-product is called co-product.
•This co-products is like coke oven gas and
other liquid products like tar, benzol,
naphthalene, phenol etc.
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3. TYPES OF CARBONISATION:-
•There are mainly two types of
carbonisation depending upon the
temperature upto which the coal is heated
in absence of air,
1)Low Temperature carbonisation(LTC)
2)High Temperature carbonisation(HTC)
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4. LOW TEMPERATURE CARBONISATION:-
•The karrick process
•700
0
c
•Produces – Semi coke
•Coke oven gas - 150-160 Nm
3
gas/ton dry coal
•C.V. Of coke oven gas – 6000 to 6500kcal/ Nm
3

•Ammonia – low
•Primary Tar – 10% of dry coal(Aliphatic nature) –
low market value
•Discharging of coke – Difficult
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5. •Free carbon in Tar – 5 to 10% of Tar
•Coke – Weaker, Bigger in size, More reactive
•Coke produced is called soft coke
•Volatile matter – high (5-7%)
•Ignition temp.
r
- 425
0
c
•Coke yield is more. (80% of dry coal)
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6. DEMERITS OF LTC
•Coke is not mechanically strong.
•It pollute the air
•Incosistent quality of soft coke
•Co-product can not be utilised.
•Heat liberated by combustion is not used.
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7. HIGH TEMPERATURE CARBONISATION:-
•1100
0
c
•Produces – Metallurgical coke
•Coke oven gas – 290-300 Nm
3
gas/ton dry coal
•Calorific value is less - 4200 to 4400kcal / Nm
3

•Ammonia – high (10-15gm / Nm
3
)
•Tar – 3% of dry coal
•Discharging of coke - Easier
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8. •Free carbon in Tar -15 to 20% of Tar
•Coke – Stronger, Smaller in size, Less reactive
•Coke produced is hard coke
•Volatile matter – Less(1-2%)
•Ignition temp.
r
- 600
0
c
•Coke yield is less.(75% of dry coal)
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10. 150130121047
Cokemaking Animation- Coal to Quenching Operation[via torchbrowser.com].mp4

11. PHYSICO CHEMICAL CHANGES DURING
CARBONISATION OF COAL:-
•Raw coal(400
0
) Plastic layer (450- 600
0
)

Semi coke High temperature coke
Median crack in coke.
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METALLURGICAL COKE PRODUCTION BY H.T.C.
•Mainly two types of ovens are used:
1)Beehive coke oven
2)By-product coke ovens:
(a)Waste heat ovens
(b)Regenerative ovens

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•(1)Beehive coke oven:-
• Dimensions: Height-2 mtr,
Base dia-3.5mtr, capacity-5.7
tons of coal
• Air is supplied initially to
ignite the coal.
• Carbonisation starts
proceeds and complete in 2 to
3 days.
• The hot coke is quenched
with water and discharged.
• No by-products are recoverd

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15. MERITS OF BEEHIVE COKE OVEN:-
•Strong coke having good reactivity are produced
•Low capital and running cost
•It can be shut down without any damage to
refractory
•Produces hard coke for foundry
•Simplicity of construction
•No extra fuel is required for heating
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16. DEMERITS OF BEEHIVE COKE OVEN:-
•No by products recovery is possible
•Lower coke yield due to partial combustion
of coal.
•Lack of flexibility of operation
•Large coking time (i.e. 2-3 days)
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17. (2)BY PRODUCT COKE OVENS:-
•It consist of rectangular chamber of L-
15mt, H- 5mt, Width- 0.4mt, with
removable doors at both ends.
•Composition of flue gas (CO 7-8%, H
2

60%, CH
4
25%, Co
2
2-4%, N
2
-3%)
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18. (a)WASTE HEAT OVEN
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19. (b)REGENERATIVE COKE OVEN
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20. •Flue temp.
r
– 1200 to 1300
0
c
•Carbonisation time of 22 tons of wet coal – 16 to
18 hours
•Dry quenching – inert gas (N
2
)
•Both ovens Similar in operation.
•But it is differ,In waste heat type, steam is
generated by the hot flue gas by transferring its
heat to a waste heat boiler
whereas in regenerative ovens, combustion air is
preheated in regenerators which is heated by
hot flue gases.
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21. MORDEN TRENDS OF COKE MAKING
•This aims the reducing specific heat
consumption in coke making by way of
fuel economy techniques and high
prodctivity of coke oven.
•1.35 ton coal is req.
r
for 1 ton of hot metal
•Carbonisationof 1 ton coal is req.
r
0.6 *
10
6
kcal
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22. •So, energy conservation in coke making
can be done by many techniques.
•There are washing of coal, Blending of
coal, Preheating of coal charge, Use of
coal briquettes, Addition of coking agents,
Formed coke, Dry quenching of coke,
Stamped charging of coal and many
others.
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23. COKE OVEN PLANT
•In india mostly the coke oven plants is in
steel making and iron making industries.
•World’s 1st coke oven plant is in south
corea.
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Coke Plant Technologies[via torchbrowser.com].mp4

24. REFERENCES:-
•Fuel, furnace and refractories book by o.p
gupta
•Fuels and refractories Book by J. D.
Gilchrist
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25. THANK YOU