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Annealed coal

The opposite of cryogenically treating organic polymers to make them tougher; warming coal to noncombustion temperatures for 5-24 hours may make the coal particularly flammable (more joules/second emitted))
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What if coal becomes particularly easy to molecularly shake apart if it is non-combustively heat treated, reverse cyogenically-hardened in a sense? You would get more joules/second out of lesser grades of coal, improving efficiency, or reducing combustion chamber size for higher output.

This is the opposite of cryogenically treating organic polymers (published are hardwood and bamboo [link]) to make them tougher; warming coal to noncombustion temperatures for 5-24 hours may make the coal particularly flammable. The possible % gain in joules/second is as far as I know unresearched, but if if coal becomes 9-27% "less tough" to combust then entirely new kinds of coal fueled power plants could be developed.

Also, they could do a stepwise examination of pollution produced by coal treated from -170C to +227, at 1 degree intervals to see if any of the temperature pre-treatments have a "least pollution" producing profile. It's possible that cryogenically treated coal is anthracite-ish even though it is a less carbonaceous coal.

Now, if warming coal (annealing) to +220-227 causes efficiency gains, it seems like just storing the coal next to the smokestack could produce this degree of warming. Although possibly otherwise at cogeneration applications, and thermoelectric electricity generation, which might be more efficient uses of the 220-227C warmth.

Solar thermal treatment of coal is also a possibility (cofocal mirrors on outdoor coal transport channels) at some weather pattern locations.

If, conversely, cryogenic treatment of coal is beneficial, either from an efficiency (imitation anthracite joules/second even with less carbon) or pollution perspective, the cheapest refrigeration I am aware of is ammonia freeezers. and a 2020 published value is -80 F.

The thing about freeze-treating coal is that, obviously shorter freezer durations are more energy efficient, but, then again, once it is only at -80F, perhaps you can leave it at that for 240 hours instead of 5-24 hours (established "give it a day" cryogenic treatment practice) but for 240 hours (an order of magnitude more freezer time to make up for the cheap, comparatively warmer -80F ammonia freezing).

It's unclear from the internet thing I read, but ammonia alone refrigeration may reach -120 C or better

And, just as an aside, treating coal with cryogenic freezing has a winter advantage; Even just doing it in Northern Hemisphere cold weather season could start the the refrigeration process at outdoor winter temperature of 0C. Freezing from that is cheaper than 28C summers.

beanangel, Jan 09 2021

Coke https://en.wikipedia.org/wiki/Coke_(fuel)
cooked coal [prufrax, Jan 09 2021]

breeding cryogenically treatable wood that is even stronger than usual lumber from cryogenic treatment Breeding_20cryogeni..._20treatable_20wood
[beanangel, Jan 09 2021]

Smokeless fuel https://en.wikipedi...wiki/Smokeless_fuel
Baked. Literally. [8th of 7, Jan 10 2021]

Great Smog of London https://en.wikipedi...reat_Smog_of_London
Rather unpleasant. [8th of 7, Jan 10 2021]


       I would point out that a lot of the coal we use was mined and/or moved via geologic process from deep underground where the temperatures are hotter. A survey of the difference between coal in uplifted rock and coal that probably has always been near the surface may be enlightening.   

       Of course this is confounded by the differing chemical compositions not related to heat.
Voice, Jan 09 2021

       More fuel to exacerbate global warming. No smart money will be going towards coal. This is especially true now that Trump is a has-been loser. Trump loved coal, so that tells you it's completely toxic and won't attract any research investment, except to find ways to get rid of its use.
xenzag, Jan 09 2021

       ... except for the steel industry, which is a huge user and for which there's no technical alternative (to the blast furnace).   

       Oh, and cement manufacture, another big consumer.
8th of 7, Jan 09 2021

       But the idea does seem quite focused on thermal coal which, as [xenzag] remarks, is on the way out.
pertinax, Jan 09 2021

       If coal is heated to 220C, some of the volatiles will be driven out- the proportion depends on the coal type. Bituminous coal will probably give off a lot, anthracite very little.   

       Now, those volatiles are probably mostly hydrocarbons, if the heating is anaerobic, and they most likely have a lower energy value per kilo than pure carbon.   

       That means you're expelling a less energy-dense fraction, at the expense of the energy required to vapourise it.   

       So, the result is a hot, anaerobic fuel gas stream, probably sour with sulphur and ammonia - and residual carbon remaining in the retort/kiln.   

       This actually sounds a lot like the process for making "smokeless" coal.   

       If you process the gas stream for feedstocks, it could have significant commercial value, as does the residual carbon, but the economics hinge on the energy recovery from the annealing outflow... at 200C, that's plenty hot enough for a steam turbine, so this could run as a topping cycle in a generation plant...
8th of 7, Jan 09 2021

       //to get more energy out//   

       To be fair, I think the proposal is not to get more energy out, but to get the same energy out faster - that is, to get more power out (for a shorter time per unit of input mass).   

       Still a bad idea for [xenzag]'s reason, but not a violation of thermodynamics.
pertinax, Jan 10 2021

       Depends on circumstances. Didn't we toss about ideas a few years ago for decreasing air pollution in Tibet ? Concerned coal ; concensus was to make brown coal into black coal.
FlyingToaster, Jan 10 2021

8th of 7, Jan 10 2021


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