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# Wildfire suckback

pull fires back, reduce pollution
 (0) [vote for, against]

One of the major sources of carbon monoxide pollution is forest fires. The simplified reaction is:

2C + O2(limited) = 2CO+a little heat.

But when there is abundant oxygen,

C + O2(abundant) = CO2+more heat

You can see this reaction by blowing into a campire. The extra airflow causes the fire to flare up a little, because more oxygen is near the logs.

That is the tradeoff. If we assume it is better to have complete combustion, here is the method I propose:

Find a fireproof, lightweight material, to produce an inflatable "chimney". I think 200 meters should be adequate, and but this will also require "tripod" tethering.

Position the chimney on top of charred ground after the fire has passed. You may have to drop some water to make it safe for a ground crew.

Put blowers at the base of the chimney to suck air and push it up through the chimney. Hopefully, the effect will be to created a low pressure center behind the fire. Rather than winds driving the fire to spread, the winds will blow against the fire, and push the fire back to already-burned ground.

The fire will burn hotter, but spread slower. And the combustion will be more complete, producing less carbon monoxide. And because the combustion is more complete, the fire will create slightly less gas, weakening it's ability to propel itself forward.

Also, ground level pollution will be reduced, because the 200 meters should hopefully be enough height to overcome the layering of the atmosphere, allowing the hot air to rise faster via convection after being expelled from the chimney.

Optionally, water can be sprayed in the tower to extinguish any embers that get into the fan. While the system already functions like a catalytic converter, catalytic converters can be added to the intake of the chimney to further reduce pollution.

If the system can be delivered and inflated in a matter of just a few hours, it might be able to do some good against a large wildfire that would otherwise last many days.

The generators to run the fans will need to be fireproof or come with a sprinkler system, and be rainproof. Or, if their is a buried power line nearby, a generater might not even be needed.

An example of the tethering needed. http://www.pacifics.../laturnus/tower.htm

(?) Firefighting bombs Firefighting_20bombs
LOx bombs are even better than the above idea. Bring your bagels. [bungston, Oct 03 2005]

here's an article about how air sometimes has temperature inversions http://unisci.com/s...s/20021/0221022.htm
If one can pierce the lower layers, the pollution will go up and stay up. [Madai, Oct 03 2005]

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Annotation:

 You start with talk of carbon monoxide, but the idea then becomes a giant fan to suck wildfires backwards. I am not sure how CO is involved with the giant fan.

 If you position your giant fan in front of the fire, it would not need to be fireproof, and could directly blow it backwards.

 Or best of all, and accomplishing all you want and so much more: fans blowing pure oxygen at the back of the fire. This would accelerate and enhance combustion of groud which has already burned, completing combustion and getting rid of CO2. The enourmous heat from the O2 fueled fire will itself be your chimney, with heated air rushing skywards, sucking the front of the fire backwards. No need for inflatables.

In fact this could be even better (if that is possible!) accomplished not with blowers, but with LOX bombs dropped from a plane behind the advancing front of the fire. This would also be safer for all involved, and as an added plus uses bombs.
 — bungston, Oct 03 2005

 The more oxygen that passes over the fire, the more complete the combustion. So a fire that is blown on will produce more CO2.

 I've read all the other wildfire ideas, this idea takes a different approach. Dropping O2 behind a fire would push it outward even faster. Dropping lox in front of a fire would not be smart either. LOX turns charcoal into the equivalent of dynamite. We don't want that, for this idea. We want to *gently* push the fire back into itself, not blow it to smithereens.

 imagine a fire that burns outward in a perfect circle. you would have black center, that is already burned, then a red ring around the black, the part still on fire, then a yellowish ring around the red-- the part that is tinder dry but has not caught fire yet.

 To push a fire from the outside would require fans to encircle the fire completely. That's a lot of fans.

 if you put a fan in the center of the black, you would suck in the fire equally, with only one fan.

The reason why you want a chimney is because air columns stagnate. Take a stack of books. Imagine the bottom book is 100 degrees, the next book 95, the next book 90, and so on. the 100 degree book will only warm the 95 degree book so quickly. now, take the 100 degree book and put it between the 20 degree book and 25 degree book. Now there is much less resistance.

/Dropping O2 behind a fire would push it outward even faster/ - why? It would suck it back.
 — bungston, Oct 03 2005

 As a gas expands outward it pushes things outward. In order to suck a fire in, you would need to reduce the pressure. going back to the black/red/yellow rings, if you drop lox in the black (behind the fire), the lox will expand, it's cooled vapors(cooler, thicker air) running across the ground until it reaches the fire. Then the vapors will reach the flames and expand into a full fledged gas, and provide a rich oxygen source to the fire, as well as push the hot air outward.

 If you put the lox bomb in front of the fire(in the yellow), you make the fire burn EXPLOSIVELY hot. Any LOX-drenched dried brush might as well be TNT.

Lox cannot stop a fire. it can only fuel it, or rather, help it burn the fuel in front of it.

 / And because the combustion is more complete, the fire will create slightly less gas, weakening it's ability to propel itself forward./

Crazy idea: fight wildfires with water, not oxygen.
 — Texticle, Oct 03 2005

/full fledged gas/ Gas is gas. Increased oxygen = more combustion = more heat = less pressure on the ground as heated gases move skyward. Any increase in pressure produced by evaporating LOX will be greatly outweighed by the chimey effect of the combustion it produces.
 — bungston, Oct 03 2005

 //Gas is gas.//

 yes, I wasn't being really clear. you remember the day your physics professor, or however, showed you some liquid nitrogen? you remember how you could see the liquid nitrogen vapor bubbling out of liquid as it slowly boiled? That was vapor. ordinarily, nitrogen is so thin, and warm, that you cannot see it. only when it is vapor can you see it. Vapor is gas, if you want to go with the 3-state paradigm, but it's a special case of gas.

 //Any increase in pressure produced by evaporating LOX will be greatly outweighed by the chimey effect of the combustion it produces.//

 I heartily disagree. The explosive force of the oxygen's expansion will go in all directions, up especially, but not at all exclusively . Giving a fire more oxygen is a mistake.

 Texticle, by gas, I mean all gasses released by a burning object. During incomplete combustion, carbon produced carbon monoxide.

 2C + O2 = 2(CO)

 So, for every gas molecule of O2 that feeds a poorly oxygenated fire, 2 gas molecules are created.

 consider the other case, complete combustion:

 C + O2 = CO2

 Now, every oxygen molecule is replaced by just one carbon dioxide molecule. Complete combustion produces less gas.

 Also, while CO2 is dangerous, CO is much more dangerous. More complete combustion = less pollution. Thats why cars have catalytic converters.

 My idea is basically a giant catalytic converter for a wildfire. It's not meant to replace fighting fires with water but to augment it.

If fact I should probably add typical catalytics to the chimney intakes.

 Less gas? No.

 True every O2 molecule creates only one CO2 model in the case of complete combustion, but there are much more O2 molecules in that case (abundant as opposed to limited oxygen).

Consider each carbon instead - that is what is of relevance here. And don't be fooled by the balancing of the equations when doing that...not that you would.
 — Texticle, Oct 04 2005

The product is CO2 and water.
 — Antegrity, Oct 04 2005

 texticle, you do have to pay attention to the amount of oxygen. let's suppose you have a basic sugar:

 C6H12O6

 Lets say a parcel of air that passes by this sugar has 3O2 and 17N2, and has a pressure of 1 atmosphere.

 During combustion, of course, the water locked up in the sugar is driven off, becoming 6H2O.

 Carbon combustion will be incomplete:

 3O2+6C = 6CO

 20 molecules went in. 29 molecules came out.

 Now let's suppose the parcel of air is oxygen rich:

 6O2 + 14N2

 You still have the H2O, but, you don't get extra molecules from the incomplete combustion.

 6O2+6C = 6CO2

 so, 20 molecules go in, 26 go out.

 Now, forget the starting 20. You have 6 and 9. Incomplete combustion produces 50% more gas compared to normal combustion. What happens to the oxygen is more important because it was a gas to begin with.

 I'm simplifying, but my point remains.

And anyway, the important thing is to reduce the pollution, and to steer the pollution away from ground level.

the fire will tend towards areas of higher oxygenation. this idea would simply fan the flames, making the situation worse. unless you think this chimney will produce tornado strength winds that will such all the local atmosphere and fiery debris through it. i notice that this is mainly about reducing pollution caused by forest fires, but im not sure tons more of one gas is better than another. also, the updraft from a hot fire creates a similar effect.
 — schmendrick, Oct 04 2005

 Fire tend to create their own weather, pushing themselves onward.

 The sucking should at least at counteract the fire's own *whether* to a small degree. Since the fire will burn hotter, the updraft will be enhanced. Burning embers will hopefull be sucked back into the bruning zone instead of falling on unburned fuel.

 As for carbon monoxide being worse than carbon dioxide, this should not even be up for debate:

 400 ppm of carbon monoxide is lethal. Permanent brain and organ damage can occur well below that.

 At 600 ppm carbon dioxide, you might be able to notice dioxide if you are very aware. It takes prolonged exposure above 5000 ppm to be dangerous, and 30,000ppm before it is lethal.

So, yeah, turning carbon monoxide into carbon dioxide is looking like a pretty damn good idea.

 [Madai], I disagree re: the gas volumes.

 C6H12O6 + 6O2(abundant) = 6CO2 + 6H2O

 C6H12O6 + 3O2(limited) = 6CO + 6H2O

 So every molecule of sugar, when combusted, either completely or incompletely, produces 6 Carbon-n-oxide molecules and 6 water vapour molecules.

 I’ll assume both CO2 and CO are ideal gases i.e. they both take up the same volume. Therefore gas volume as a product of combustion is the same in my opinion. The only thing different is the amount of oxygen (limited or abundant) that you started with.

I am open to correction though.
 — Texticle, Oct 04 2005

 Your equations are correct, you're just not looking at them the same way I am.

 In complete combustion, you go from 6 gas molecules to 12. The number of gas molecules has DOUBLED.

 In incomplete combustion, you go from 3 gas molecules to 12. The number of gas molecules has QUADRUPLED.

 It does matter what gas you started with. The number of molecules a sugar will give off is constant, I give you that, but since incomplete combustions consumes less EXISTING gas, the volume of gas will be greater.

 You are saying: 12 = 12, I am saying: (12 - 3) > (12 - 6)

You see, now?

Hey man whatever you say.
 — Texticle, Oct 05 2005

//So, yeah, turning carbon monoxide into carbon dioxide is looking like a pretty damn good idea.//
funny
 — schmendrick, Oct 07 2005

Point of fact :
2C + O2(limited) > 2CO
is an endothermic reaction - it requires heat. The following oxygenation of carbon monoxide is exothermic.
 — Loris, Oct 10 2005

//LOX bombs dropped from a plane behind the advancing front of the fire. This would also be safer for all involved// [Bung] - I can't believe that you have considered the health and safety implications of dropping liquid oxygen onto a forest fire, beyond the obvious: don't. There appear to be a number of insanely lethal plans here, all vying for acceptance.
 — wagster, Oct 10 2005

 Loris, I thought CO production was exothermic, but produced less energy than CO2 production? The ratio is about 2.5x or something. For a quick example: Blast furnaces work by burning coke, and reducing FeO. Reducing FeO is endothermic, but anyway, heat is produced in the blast furnace. The interesting gas offtake from Blast Furnaces is CO, which can be later used in power generation on site. CO is produced when the temperature is high, even if there is enough oxygen available.

However, I think there is another reaction which *is* endothermic: C02 +C > 2CO.
 — Ling, Oct 10 2005

How's about an iceberg trebuchet? You just launch are really really big iceberg at a wildfire and let it cool down the fire! I just hope whoever fires the thing misses my house.
 — Willie333, Oct 10 2005

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