Can a new desalination method revolutionize access to clean water?

[jim meyer]

If sea water is confined in a vacuum of 600 Pascal pressure it will boil and cool until ice forms. There are several problems designing a system using this process. But, when all the engineering is done and a practical system is developed this method will produce potable water from seawater far more efficiently at less cost than the best currently available system. How can interest in developing stuff like this be generated? thanks

 

[billy_joule]

If sea water is confined in a vacuum of 600 Pascal pressure it will boil and cool until ice forms. There are several problems designing a system using this process. But, when all the engineering is done and a practical system is developed this method will produce potable water from seawater far more efficiently at less cost than the best currently available system. How can interest in developing stuff like this be generated? thanks

That sounds like the traditional method for desalination to me;

The traditional process used in these operations is vacuum distillation—essentially the boiling of water at less than atmospheric pressure and thus a much lower temperature than normal. This is because the boiling of a liquid occurs when the vapor pressure equals the ambient pressure and vapor pressure increases with temperature. Thus, because of the reduced temperature, low-temperature "waste" heat from electrical power generation or industrial processes can be used.

https://en.wikipedia.org/?title=Desalination

 

[jim meyer]

Billy, This method you describe is not anything the same thing I am suggesting. The vacuum I am describing will produce ice as well vapor and has a operating temperature at ~-5/+5C. You need to study these systems to see how well they really work.

 

[billy_joule]

Maybe you could provide a link or more information on your proposed system?
My intuition tells me making ice when you want water will not be competitive, efficiency wise, with traditional desalination. I don't see how reducing the temp and/or pressure until freezing occurs will be of much benefit, the enthalpy of fusion will be wasted energy (unless of course the icebox comes back into vogue!).

 

[jim meyer]

Your instincts are right if you a think about it in conventional ways like they say when using in use methods. I am saying that by making the vacuum and then using raw seawater or waste water or brackish water the ice can be made as vapor is removed and condensed. I never posted anything on line about this as far as I recall, but I did write the DOE several times. They never commented because it was not will enough developed. It's a big job as you might know involving millions and lots of engineering. Lately I've been working on some of the details like how gravity can be involved in the vacuum chamber and how to get the ice out. I know how the vapor needs to be removed as well as about how much energy is required to do the job.

 

[berkeman]

The vacuum I am describing will produce ice as well vapor and has a operating temperature at ~-5/+5C. You need to study these systems to see how well they really work.

Maybe you could provide a link or more information on your proposed system?
My intuition tells me making ice when you want water will not be competitive, efficiency wise, with traditional desalination. I don't see how reducing the temp and/or pressure until freezing occurs will be of much benefit, the enthalpy of fusion will be wasted energy

Yes Jim, you need to post links to published works about the method you want to discuss. What is your training in engineering and thermodynamics so far?

 

[jim meyer]

Hi Billy, as I implied in my posts here as far as I know nothing has ever been published about this.

 

[berkeman]

Hi Billy, as I implied in my posts here as far as I know nothing has ever been published about this.

Okay, Jim, if nothing has been published about it before, and your idea is unique, non-obvious and useful, you should be careful about talking about it in public forums. That can nullify any patent possibilities for the process. It's important that you protect your idea as you develop it, so that you can profit from your ideas when they work. I'd recommend that you talk to a local consulting engineer to help develop your idea. He or She would be able to talk through the thermodynamics of your idea, and let you know if your idea has merit or not. If it has merit, the consulting engineer will help you keep your idea private until the patent applications are filed.

This thread is closed.

 

[berkeman]

Thread re-opened at the request of a subject matter expert.

 

[jim meyer]

Hi Expert, As an expert you know these systems have been around a long time and the best system is nature's own powered by solar. We humans don't hold a candle to natural ways of purifying water. Many types of systems have been designed and all of them cost too much for general use.The least costly way currently available is R.O. for stand alone systems. It seems to me a much more efficient(cost wise) way to make potable water is a freeze system. This method has never been researched in any depth because water has never been that great a problem. We just wait for rain or make canals the Romans would be proud to own or just move to greener pastures. Anyway, I don't have any intellectual property worth patent protection or money to invest in pursuit of it. I do know the physics indicates what I have posted above can be obtained with current state of the art and potable water can be produced at a much lower cost than it is being done at this time by the best man made systems.

 

[rootone]

Firstly, I am not the expert, but I am following this topic.
I would like to know why it is that freezing the water after having purified it has an advantage,
or is the freezing necessary as part of the purification method?

 

[jim meyer]

Freezing purifies water just as vaporizing does.

 

[rootone]

Are you sure about that?
Sea water freezes naturally in polar regions, and the resulting ice contains a lot of NaCl seasalt plus other impurities.
Maybe you have a special method of freezing though, and if so you won't want to reveal the details before having patented the process.

 

[jim meyer]

Quite sure of this fact. Sea ice has all kinds of stuff not related to the fusion of liquid to solid.

 

[rootone]

Hmm, yes I did quick fact check on sea ice, and it seems that although newly formed sea ice has a high salt content, if it remains frozen for several years the impurities slowly leech out of it.
If you have discovered a way to accelerate that process to be effective in few days rather than years it does seem plausible.
Let's wait and see what the expert who asked for this thread to be reopened has to say.

 

[jim meyer]

Rootone, I just said there is nothing new and therefore patentable here. The area has never been explored much like most of our planet which is undersea-but I digress. I don't have time or money to pursue intellectual rights. As for the salt problems-they are minor compared to real problems engineering might resolve in time.

 

[russ_watters]

Freezing purifies water just as vaporizing does.

I'm not the expert either, but I also think this is wrong and would like an explanation.

Vaporizing water is, itself, a purification process: when the water evaporates, it leaves the impurities behind. Not so with freezing: when water freezes, most impurities freeze with it.

So if you have a method for removing the impurities from ice that is already formed, that would be a wholly different (and useful) thing. Is that what you are suggesting?

 

[jim meyer]

Hi Russ, Try a simple experiment you can do at home-put a quart of milk or orange juice in the freezer compartment of you refer. In a day or so you will find ice on top and muck on the bottom-the ice can be examined anyway you wish and it will be pure H2O. What I am suggesting is developing a method of moving heat from seawater by evaporation cooling it to a point where ice forms. Nothing more than that. It is a very simple well researched process.

 

[russ_watters]

Hi Russ, Try a simple experiment you can do at home-put a quart of milk or orange juice in the freezer compartment of you refer. In a day or so you will find ice on top and muck on the bottom-the ice can be examined anyway you wish and it will be pure H2O.

I have done this: in my freezer right now is a bag of Gatorade Cubes I use for biking. When I freeze them, a small portion remains muck and I use that in the next batch. The rest is frozen Gatorade.

Kids also make popcicles this way.

 

[jim meyer]

Hi Russ, OK you win-its something I did as a kid too. The ice in the Popsicle is still ice as is the ice in the gator aid and the sweet stuff in not ice. This is a very interesting bit of physics best for some other thread. Its really way off the point here.

 

[Rippetherocker]

I'm not an expert as berkeman said lol but i do work on such systems on a daily basis.
Standard plants are maintained at 90% vacuum for a reason. It keeps the boiling point at around 50°C.

Do you know why? Its because at greater vacuum the water will flash almost instantaneously and salt particles will go up along with the vapour and demisters can't stop this.
Salinity of distillate will keep on increasing.
Also the feed can be heated more to facilitate production but the higher temp. Cause hard scales.
Evaporation desalination systems have been done to death by multi billion corporation R&Ds. I'm not trying to be discouraging but I'm not sure anything significant is left here to be discovered.
We need energy efficient systems not power hungry farms who waste energy in latent fusion.

 

[Rippetherocker]

And just to add we've all had that eureka moment when we thought we could change the world. We know how you feel! The people here on this forum are "experts" so heed their advice.

P.S. - Anyone who calls himself an "expert" is automatically stupid in my book.

 

[jim meyer]

Hi Ripper, I would love to hear more from a hands on guy about how these systems perform. Are you talking about using steam in a multi-flash design? If so, what is the pressure of the feed stock(steam)? If you read my posts here it seems we are talking about two very different ways of getting from point "A" to point "B" unless I missed something. I am attempting to perfect a freeze system that would be very efficient although I'll admit its a bit like attempting to juggle boiled noodles.

 

[Rippetherocker]

Look man I'll tell you as simply as I can.
Forget the heat source. For you to get pure ice you need pure water vapour. You CAN get pure water vapour from sea water but it will be miniscule. So you increase the rate of evaporation by increasing the vacuum, at the cost of purity.
I've detailed the rest already. To get 20tons of fresh water of salinity around 20ppm per day you need total flow maybe 500 tons. Who know? I havnt calculated.
Tell me in detail your plan and I'll tell you the stumbling blocks.
i suggest you download and read let's say the alfa laval fresh water generator manual.
good luck.

 

[Rippetherocker]

And btw berkeman your a great mod.
Also is that you on the bike?

 

[berkeman]

And btw berkeman your a great mod.
Also is that you on the bike?

Thanks

Yep, that's me on my CRF450R motocross bike a few years ago. Berkeboy is grown up now, and we don't ride much MX anymore. We're both on sportbikes now

https://www.physicsforums.com/threads/how-many-of-you-ride-motorcycles-scooters.813943/#post-5110766

.

 

[256bits]

Hi Ripper, I would love to hear more from a hands on guy about how these systems perform. Are you talking about using steam in a multi-flash design? If so, what is the pressure of the feed stock(steam)? If you read my posts here it seems we are talking about two very different ways of getting from point "A" to point "B" unless I missed something. I am attempting to perfect a freeze system that would be very efficient although I'll admit its a bit like attempting to juggle boiled noodles.

Here is some information on freeze purification.

Basically you are working with a eutectic phase diagram as illustrated in the given links.
http://www.imwa.info/docs/imwa_2009/IMWA2009_Nathoo.pdf
http://www.wmconlon.com/wp-content/uploads/papers/IATC92.pdf

Might as well add in a wiki
https://en.wikipedia.org/wiki/Fractional_freezing

 

[jim meyer]

Hi Ripper&265, You guys are great. The Conlon paper is the best paper I've seen about this detail of a complex subject. My idea is still different in that first off it might not even be practical and second it would not need cooling other than what is done by boiling the seawater. The seawater is boiled by reducing the pressure well below what current best available systems operate at. Basically the design is quite simple but, the devil is in the details as they say. Anyway, I would lift the seawater 9.8 meters by vacuum in order to maintain a low enough pressure for the water to boil and remove the vapor(~500 cubic meters per kilogram) which is the first problem. Now a column of very cold seawater will begin to develop ice I would suppose. Lots of problems popup which might be overwhelming. Still-you know-maybe they can be worked around and a really good device can be developed to supply huge volumes of potable water.

 

[Rippetherocker]

As you have probably read in the wiki you need several freezing and thawing cycles for it to be drinkable.
1)You will need the machine to work continously not in batches.
2) At such a great vacuum a huge amount of salt will contaminate the vapour i.e. unusable.
3) The remaining sea water in the column is brine i.e. conc. seawater
4) your method will produce large amounts of salty fresh water, lesser salinity than sea water but not by much.
5) your system is exactly like current systems with only the vacuum increased.
6) LET IT GO...or study engineering then let it go.

 

[jim meyer]

Hi Ripper, Of course you are right as far as engineering at this time goes we are limited just as our Roman ancestors were. We can't make a good vacuum and we can't freeze seawater without it being salty. But, why it this a fact of life when nature does with ease? Don't you think something might be wrong with the way we do things now? And even more important might you think better ways of doing things can be developed by playing around with concepts like this? I,m not looking for money-I'm intelectually involved. BTW, Your 1st comment about working continously is on my to do list.

 

[rootone]

Nature does it on a grand scale though.
Huge volumes of water vapour are being shifted around the globe, some of which condenses out as rain or snow.
Often that condensing is caused by air being forced to cross over high mountain ranges.
The other primary cause is when a mass of warmer air (which holds more H20) collides with a mass of colder air.
It's hard to imagine an effective scaled down version of the way nature does it.

 

[jim meyer]

Hi, Yea, for nature does it big time. I see it as energy in motion and scale is mostly a matter of perspective. On a grander scale clouds of dust in space condense and evaporate over light year scales doing the same stuff. I think nature shows us the way to desal her way is to use solar. That would be least costly all around. These machines of our forefathers really are net very good at all and everyone knows it.

 

[Rippetherocker]

Hahaha I surrender!

 

[jim meyer]

Reviewing what you guys have said so far it is you can't get past the salt problem I consider to be a strawman. Making a mountain out of a molehill or missing the forest becausse the tree is in the way. Clearly the salt will stay in the liquid and the ice is pure H2O-that is a physical fact and it is your machine at fault. I agree your best is not good enough to do the job. The real problems are getting stuff to flow in paths that will make the process work. Ice can be made anywhere within the column and doesn't have to melt at all. And if you think for a moment you will see ice can't support salt even as well as vapor can. Only liquid H2O makes the right connections with salt to make a solution like seawater. I hope you can get over this kind of thinking (AKA common sense). How did I get in this anyway?

 

[russ_watters]

I really can't make heads or tails of what you are trying to do. If you drew a diagram showing the steps in the process and inputs and outputs of mass and energy or listed the steps sequentially for us, it might help.