Starting fire with water

Jan 13, 2014 by Dr. Tony Phillips
Starting fire with water
This is the rack onboard the ISS where the Super Critical Water Mixture experiment takes place. 

When firefighters want to extinguish a blaze, they often douse it with water. Astronauts on board the ISS, however, are experimenting with a form of water that does the opposite. Instead of stopping fire, this water helps start it.

"We call it 'supercritical water,'" says Mike Hicks of the Glenn Research Center in Ohio. "And it has some interesting properties."

Water becomes supercritical when it compressed to a pressure of 217 atmospheres and heated above 373o C. Above that so-called critical point, ordinary H2O transforms into something that is neither solid, liquid, nor gas. It's more of a "liquid-like gas."

"When supercritical water is mixed with organic material, a chemical reaction takes place—oxidation." Says Hicks. "It's a form of burning without flames."

This really comes in handy when you want to get rid of certain unpleasant materials—like sewage. Cities, corporate farms, ships at sea and manned spacecraft accumulate waste materials that could benefit from this kind of treatment.

"When we push a wet waste stream above the critical point, supercritical water breaks the bonds of the hydrocarbons. Then, they can react with oxygen." In other words, the slurry ignites. Sometimes, hotspots in the slurry produce visible flame, but usually not. "This is a relatively clean form of burning that produces pure water and carbon dioxide, but none of the toxic products of ordinary fire."

What does all of this have to do with the ISS? "The International Space Station provides a unique microgravity lab for studying the properties of supercritical water," explains Hicks.

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One of the problems with supercritical water has to do with salt. Above the critical point, any salts dissolved in water quickly precipitate out. If this happens in a reactor vessel, the metallic components of the vessel become coated with salt and they begin to corrode.

"In any realistic , we have to learn how to deal with salt. It's a major technological hurdle."

Dealing with salt is the ultimate goal of the Super Critical Water Mixture experiment on the ISS, a joint effort between NASA and CNES, the French space agency.

"By studying supercritical water without the complicating effects of gravity, we can learn how precipitating salts behave on a very fundamental level," says Hicks, who is the principal investigator of the experiment. "We might even be able to figure out how to draw salt away from corrosion-sensitive components."

The experiment, which uses French-built hardware (DECLIC) located in the station's Japanese Experiment Module (JEM), began during the first week of July 2013. It will continue for a full year in a series of six test runs, each lasting approximately 15 days.

The results could have down-to-Earth applications. The US Navy has already started using supercritical technologies to purify waste streams onboard some of their ships, while the City of Orlando has started a supercritical treatment plant for processing municipal sludge.

Explore further: NASA launches new citizen science website; opens challenge to participate in future Mars missions

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Returners
1 / 5 (1) Jan 13, 2014
Isn't this thermolysis, but just at a lower temperature?

For example, with a powerful enough magnifying lens, you can "Burn" wood chips inside a vacuum (like in a jar,) even in the absence of oxygen or any other obvious oxidizing agent.

My assumption is this breaks the covalent bonds directly, and then water and carbon alotropes are formed from the elemental ingredients of sugars and cellulose, not to mention other trace elements like sulfur and phosphate. I've obviously no access to a mass spectrometer to see exactly what compounds are made in this process from any random piece of wood, but as I see it, the process supposedly makes a lot less pollutants than burning in the presence of oxygen.

This can also be done with the wood submerged in a jar of water, with the chemistry probably being very similar to that discussed in the article, except that you can focus the beam on the wood itself, "burning" the wood without heating the entire volume of water to boiling or supercritical.
Returners
1 / 5 (1) Jan 13, 2014
I think you could separate the salts by having the water periodically got into another chamber (for a mediating point) close the valve between the two, then move the water into a spinning, centrifuge like device which will simulate gravity. Here the water is allowed to boil, the salts precipitate on the outside of the centrifuge, while the water vapor is drawn off into yet another container for condensation. The centrifuge would haven an augur built into it to scrape the salts from it's walls once the water has been fully vaporized, this way the system is mostly self-cleaning. The salt is pumped (via the augur) into another container, and the system is then re-loaded.

Of course, building this for space purposes my require a nested centrifuge, that is with two axis of rotation, in order for this to actually work.

Think about an amusement park ride, like the "Gravitron," except this wheel would be tilted up by 90 degrees on another central axis which is itself rotating.
Returners
1 / 5 (1) Jan 13, 2014
Oh yeah, in the magnifying lens (Fresnel lens) example, you must avoid letting the focal point hit the glass directly, or you could shatter the glass due to thermal shock.

Here's an example of burning wood and igniting fireworks under water using a Fresnel lens.

http://www.youtub...bRgwK1Dc

Obviously the water never boils, and never gets anywhere near super critical, but the 2x4 is clearly burning from the focal point of the lens.

I know I saw him do another one with a jar and submerged garbage and wood chips, and I think (or maybe it was someone else,) I think he has a video of burning wood in a vacuum using the Fresnel lens.

It's counter-intuitive, but you don't need an oxidizing agent to disintegrate the materials. You just need to hit it with enough heat and photons to overcome the bond energy, and re-arrange the atoms into different molecules.

The point was to disintegrate the material without making CO2.
Eikka
5 / 5 (6) Jan 13, 2014
Returners, do you know why it says "Brevity is the soul of wit" under the submit button?

It's because of people like you who talk more than they think, producing walls of irrelevant speculation.

Point in case: distilling the sludge would leave behind not only the salts, but the organic compounds that you're trying to burn.

the 2x4 is clearly burning from the focal point of the lens.


It's charring, which means the carbon matrix of the wood is left behind as the hydrocarbons evaporate due to the heat. That in itself is not burning and does not require oxygen.
Returners
1 / 5 (1) Jan 13, 2014
It's charring, which means the carbon matrix of the wood is left behind as the hydrocarbons evaporate due to the heat. That in itself is not burning and does not require oxygen.


I understand that, which is why I used the term "Thermolysis," which is technically not "burning," but that was the point. It has the advantages of "burning" without the drawback of creating CO2 pollutant.

The fresnel lens method actually requires less energy than pressurizing and heating water to super-critical conditions, but I'd say it's a bit risky in a glass container due to thermal shock. Still, it could be used in space if the crew is within about 1 a.u. or so. It probably wouldn't be enough light to do it beyond Mars' orbit though, which is a big reason the method in the article could be useful.

I don't think my posts were irrelevant, I was just drawing a comparison to similar reactions in slightly different circumstances.
baudrunner
1 / 5 (1) Jan 13, 2014
Now those ancient Sumerian documents are beginning to make a little more sense. Apparently, the Anunaki powered their rocket ships with water. The abundant methane in space would provide the carbon for the reaction. Imagine, powering a space-based transportation system using water and methane!
GSwift7
5 / 5 (4) Jan 13, 2014
I don't think my posts were irrelevant


I'm sorry, but you're kinda missing the point.

As the article says, this experiment is being done in space mainly as a way to observe the chemical processes better, not so they can use this in space at some future time.

Secondly, this is strictly a method for removing organic matter from water. In order to char it, you would first need to filter it out of the water. A conventional water treatment plant uses things like charcoal filters, caustic chemicals (like bleach) or strong oxidizers like ozone, as well as evaporation pools and aeration fountians to remove disolved gasses. I work at a large commercial bakery, where we use a three stage trap to collect floating or condensing material and we use a caustic solvent to help break down solids in the water, such as flour (which turns to glue in the sewer pipes if we just flush it down the drain).

Current methods are expensive and not really very effective
Returners
1 / 5 (2) Jan 13, 2014
Now those ancient Sumerian documents are beginning to make a little more sense. Apparently, the Anunaki powered their rocket ships with water. The abundant methane in space would provide the carbon for the reaction. Imagine, powering a space-based transportation system using water and methane!


In theory, you'd use water as a stable storage media for hydrogen. You'd do electrolysis to separate out the hydrogen, then do fusion of the hydrogen for enormous energy gains. The excess oxygen could be used as a propellant, or as a replacement for oxygen on board, for example you'd have some losses of O2 from airlock usage for external maintenance.

Water is nearly ideal, because you can always use that replacement oxygen.

Molecular hydrogen would be too dangerous to store on the ship long term, due to risk of fire.
Protoplasmix
5 / 5 (4) Jan 13, 2014
I think you could separate the salts by having the water periodically got into another chamber (for a mediating point) close the valve between the two, then move the water into a spinning, centrifuge like device which will simulate gravity.

@Returners, are you trying on purpose to be a source of cognitive dissonance? Did you miss this bit?
"By studying supercritical water without the complicating effects of gravity, we can learn how precipitating salts behave on a very fundamental level," says Hicks, who is the principal investigator of the experiment.

You can lead horses to water. And you can lead idiots to water. One group cannot be forced to drink. But the other group pisses in the trough. Hence the distinction.
Botopfbber
1 / 5 (1) Jan 13, 2014
I feel on a large scale this is a very bad idea. Its a fast fix we don't need that level of production of CO2. Yes use it on chemical weapons and extreme bio waste but poop and landfill waste would produce way to much CO2 those are best composted. Maybe as a final stage for the med's and compounds in drinking water yes, but not a first stage treatment. Thing is so many people will think it's a good idea, and we'll all be screwed for it; and so will our kids.
GSwift7
5 / 5 (3) Jan 14, 2014
I feel on a large scale this is a very bad idea. Its a fast fix we don't need that level of production of CO2. Yes use it on chemical weapons and extreme bio waste but poop and landfill waste would produce way to much CO2 those are best composted


You have it backwards. This process allows you to completely recycle waste material that would otherwise just go into a landfill or underground storage. They use this process to treat some of the worst hazardous waste. It could be used much more extensively, if we can figure out how to make it work better.

Here, check out the wiki page on this before you respond:

http://en.wikiped...xidation

The main problem with this process right now is that not only does the supercritical water disolve impurities in the water, it also disolves the machine it is in. This is largely due to salts. That is why NASA is working on this. This is a very green technology.
baudrunner
1 / 5 (1) Jan 14, 2014
Maybe the supercritical water reaction can be used "as is" to power rockets in space. After all, a nominal constant acceleration of only 1G will take you from Earth to Mars in about two and a half days. Operative word is "constant", mind you.
GSwift7
5 / 5 (2) Jan 15, 2014
Maybe the supercritical water reaction can be used "as is" to power rockets in space. After all, a nominal constant acceleration of only 1G will take you from Earth to Mars in about two and a half days. Operative word is "constant", mind you


Oh boy. You're really not even close to understanding what this is. Should I even bother trying to help you, or would I be wasting my time?

Do you know the difference between endothermic and exothermic? If you look up those two words, it should be enough for you to figure out what is wrong with your statement. The operative word here is "endothermic", mind you.
baudrunner
1 / 5 (1) Jan 15, 2014
@GSwift7:
"Sometimes, hotspots in the slurry produce visible flame, but usually not. This is a relatively clean form of burning that produces pure water and carbon dioxide, but none of the toxic products of ordinary fire."
The production of any compounds involve formation of chemical bonds. Those are exothermic reactions. If anything is to be gleaned from this information, it is that the process involves very efficient exothermic reactions.

The only occurrence of the word "endothermic" is in your post.
Botopfbber
1 / 5 (1) Jan 16, 2014
You have it backwards. This process allows you to completely recycle waste material that would otherwise just go into a landfill or underground storage. They use this process to treat some of the worst hazardous waste. It could be used much more extensively, if we can figure out how to make it work better...

No I don't think I do have it backwards and and all I was able to pick up from Wikipedia (I also donate to them each year BTW) supports what I said. it's used on ships on the seas and in space for good reason. It can be used for PCB's, nerve gas and such no problem with that. On a large scale, in the case of sewage sludge every city very bad idea. Nature has a way to rework that with chemistry for the good of everything, but she can't handle mega tons and we shouldn't try. If we all had composting crappers we would be much better off. This in a different form is what they tried maybe 20-30 years ago by pumping it up under liquid iron with all the same effects. large scale....NO!!
GSwift7
not rated yet Jan 16, 2014
The only occurrence of the word "endothermic" is in your post


That's right, because the article assumes this is so basic that it didn't need to be explained.

It takes a huge amount of energy to heat and pressurize the water. This energy is what is causing the organics in the water to break down and oxidize. Any flame that is produced in the reaction releases less energy than it takes to heat the water. In practice, they try to use heat exchangers and gas pressure turbines to recover as much of the energy as they can, but it's still not a very efficient process. The energy going in is much more than the energy released.

Here's a fairly easy to understand journal paper about the process, if you care to learn a thing or two:

http://users.unim...AP11.pdf

Think of this as kinda like a fancy version of distillation. You add enough heat to cause something to happen which wouldn't happen without that heat. BTW, they actually have to add oxygen as a feedstock.
TheGhostofOtto1923
1 / 5 (1) Jan 16, 2014
Well we might soon have even better uses for water

"Terry M. Copeland, PhD., MIT January 5, 2012

"In summary, BLP has successfully fabricated and tested CIHT cells capable of producing net electrical output up to 50 times that input to maintain the process. Some cells have produced steady power for over one month. The power generation is consistent with Dr. Mills theory of energy release release resulting from hydrino formation. No other source of energy could be identified. BLP has achieved a historic success for a technology that could be directly commercialized as an alternative form of power generation."
http://www.e-catw...-claims/
rockwolf1000
1 / 5 (1) Jan 16, 2014
@ boto
On a large scale, in the case of sewage sludge every city very bad idea. Nature has a way to rework that with chemistry for the good of everything, but she can't handle mega tons and we shouldn't try. If we all had composting crappers we would be much better off. This in a different form is what they tried maybe 20-30 years ago by pumping it up under liquid iron with all the same effects. large scale....


The problem nowadays is that sewage treatment plants cannot remove pharmaceutical and other chemical residues from the waste stream. These compounds produce all sorts of unwanted and poorly understood reactions in the environment and may be one of the reasons frogs are in decline. i.e. birth control pills. Elimination of these chemicals is the logical and prudent remedy.
baudrunner
1 / 5 (1) Jan 17, 2014
@GSwift7: I think you're hung up on the current limited applications of supercritical water. For example, as chemical engineer Ken Debelak of Vanderbilt University explains on the NASA site, NASA Science:
"Magnesium can be dissolved quite easily by supercritical CO2, Debelak has found. That's an experiment that we're quite excited about at the moment," he says. Magnesium, which is likely to be found in martian soil, ignites easily and can be used to fuel rockets."
That would be step two in the process, after harvesting the CO2 produced from the critical water reaction described in the article.

You gotta jump into a bigger box, man.

Eikka
5 / 5 (1) Jan 17, 2014
You gotta jump into a bigger box, man.


You got to understand chemistry first. Man.

The reason why magnesium and supercritical CO2 react easily and violently is because the bond between Mg and O is stronger than between C and O, so the magnesium strips the oxygen from the carbon and releases as much energy as the difference in energy between the two bonded states. In other words, magnesium actually burns in an atmosphere of pure CO2.

For the exact same reason, you cannot put out a magnesium fire with water. Water or CO2 for magnesium is an oxidizer and the reaction releases energy, whereas for organic carbon molecules in water or CO2 the opposite is true and energy needs to be added to get any reaction going.

KBK
not rated yet Jan 19, 2014
I'd like to thank them for proving the efficacy of Rhode's gas. Aka: "Brown's Gas".

Of Course it involved the Japanese. They've been trying to get the technological fundamentals behind Brown's Gas introduced for quite some time.

Add in that Brown's Gas, combined with some simple techniques, can be used to break down radiation, and you can see why this is coming up.