[Stoves] How to make smokeless coal?

[Andrew Heggie]

On 20 May 2017 at 19:33, Darpan Das <darpandasiitb at gmail.com> wrote:

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> 1) Is carbonisation of coal the major step to make it a smokeless fuel

I'm no expert but my take is yes and more below.
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> 2) Is pyrolysis/carbonisation/ devolatalisation the same thing?

Yes
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> 3) Are volatiles the main reason for emissions from coal cook stoves?

Not being able to completely burn these volatiles in the time the
molecules remain in the flame leads to Particles of Incomplete
Combustion leaving the flame, these are a mixture of soot and
Polycyclic Aromatic Compounds.
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> 4) How can i remove the volatiles?

By heating up the coal in the absence of air
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> 5) If I remove them then all the emissions will reduce?

Perhaps but you will still have to burn the smokeless coal completely.
What will you do with the volatiles you have removed?
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> 6) How do I decide at what temperature should I carbonise?

The higher the temperature then nearer the coal will get to be coke.
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> 7) Why is low temperature carbonisation of coal meant for domestic use and
> high temperature for metallurgical use?

What do you mean by low temperature?

The reason coke is made at a high temperature is so that it is nearly
pure carbon, domestic smokeless coal just needs the more volatile
substances removed but leaving higher tars in the coal to retain more
of the initial energy in the coal plus make it easier to light.
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> 8) Is the size of the coal not important factor to be taken into
> consideration when carbonising the coal?

I don't know
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> 9) Why is coke for domestic purpose also called semi-coke?

Because it is only part way to being coke as the pyrolysis is at a
lower temperature (typically 650centigrade rahter than 1100c when
making producer gas.
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> 10) Coke obtained from Low temperature Carbonisation same as Semi Coke?

Probably
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> 11) What are the specification for quality assurance of the domestic coke
> products? Are there any standards?

I would think there are bound to be but  I don't know them.

There are similariiities between pyrolysis of coal and making charcoal
but the by products from coal are nastier.

I suspect this is because the coal contains volatiles which are more
phenol (ring like carbon structures) like whereas wood has more chain
like structures and the lignin, which is phenol like structures are
not as complex so can burn out more completely without giving rise to
many PAHs, Also coal gives of amoniacal liquids and sulphur compounds.

Andrew

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