Vacuum Desalination
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- čas přidán 20. 02. 2009
- Create fresh water from seawater inexpensively.
The process of Vacuum Desalination takes advantage of the fact that water, when pulled upward by a vacuum, cannot rise more than 33 feet above the level of a surrounding body of water. So when a tube 50 feet tall (closed at the upper end) is inverted in a body of seawater, and a vacuum is applied, the seawater can only rise to 33 feet. The space above that water is at a very low pressure, and can be almost fully evacuated. When the pressure above the water level reaches 0.5 psi, the seawater will vaporize (boil) at only about 85 degrees F, which is the ambient temperature in the tropics. Once vaporization has occurred, the water vapor in the evacuated space can condense on a cold surface within that space, and liquid fresh water is produced on that cold surface. From there, gravity can be employed to collect the fresh water, and pump it to its destination.
Copyright P. Lawton, 2009 - Věda a technologie
Not diucussed is how you can separate the vacuum from the condensed water.
The initial vacuum will weaken due to non-condensable gases (air-including CO2) escaping the SW. Before a financial analysis is in order, a thermodynamic analysis should be performed. Take a look a vapor compression (VC) desalination. It is the most thermodynamically efficient of the the 3 thermal desalination techniques (MSF, MEE, VC). The Sandia National Lab report on Review of water resources and desalination techniques is a great resource.
Love the music choice
That music is killing me.
More than nine years after this video was published, I think it's fair to ask why plants based on this concept have not been designed and built. In fact, one has, but so far as I can find out, just the one. Vacuum distillation remains mostly a laboratory process for specialized small scale applications.
How small are we talking in gallons or litres per day
It makes more sense with using the decreasing temperature - at some point clean ice will form (on the sides) and you discard the dirty water in the middle or from between the crystals as it has a lower melting point. That's how I use freeze distillation only without the vacuum.
Another way to cut the cost of electricity would be a set of Stirling engines, heating and cooling water at different stages, recycling the energy. A combination of vacuum and those would make the trick. It may even be net-positive as you extract some thermal energy.
I'm actually working on a potential design with simplicity as it's main tennant
stirling engines would be used to pump the fresh water from a deep basin however, not for the process itsself which would, again be simplistic, utilising the atmospheric pressure of the seawater at a depth of several metres to force the water trough (a) heavy duty membrane(s) or filter(s)
ideally a large area that lays significantly below sea level would be best but if not a basin would have to be made and in this case use of sedimentary stone deposits (sandstone, marble, limestone, ...) may be ideal, the stone could be processed, however this would likely still take decades of full scale, peak efficiency exploitation to approach the dimmensions needed to hold the fresh water being produced, luckily the water could be allowed to overflow trough pipes into natural aquifers found around the near east for instance, or indeed it would be pumped up with said sterling engines (and more traditional pumps) towards area's where it is needed, as well as trough irrigation pipes into the surounding desert lanscape
the plan is far from ready to leave the drawing board but it is largely based around realising the major issues with traditional damms and mainly that they are designed by geniusses to be run by a an especially competent organisation filled with dedicated experts without taking into account the reallity on the ground, (the grand inga dam is a good casus)
meanwhile my idea is peak simplicity, NOT peak efficiency, working out the designs in my head was done thinking of what works in the third world, a truck that is patched with pieces of old toys and tape and metal parts crudely adjusted to go from one truck onto another. my plant is to be maintainable by just a couple competent experts, leading a large number of local tradesmen. electricity is not a main concern, all that can easily be won from it would be used up by the plant for it's main operations with the full realisation that every modern desalination plant utilises pumps equiped with devices meant to turn the remaining waterpressure into extra energy, but this sort of technology would be hell to maintain.
oh and environmentally the produced brine will be pumped out using modern externally driven archimedes screws, (essenttially the tube moves, the screw stays in place) and this can either be processed in a chemical factory or even turned into common eating or roadsalt trough evaporation,
by no means should brine be allowed to litter the seafloor especially near the coast
Well done CAD presentation. It takes more than 2200kJ/kg (~ 2400kJ/kg @ambient temperatures) to evaporate (flash) sea water. Without heat exchangers, your condenser will be working hard to maintain the required parameters. The sea water temperature will lower as well and require a stronger vacuum. But you have to convince investors that this process is more economical than SWRO (which requires about 30 kJ/kg including accounting for electricity produced by coal plants) for it to be viable.
Simple n wouldnt cost allot this is awesoME!!!
@Tomahawk4196 I would not use the actual mast to carry the water, rather 5 narrow pvc tubes inside it. 2 Salt going up, 2 salt going down plus one fresh going down. But if its heeled over it could be a problem thats true, never thought of that...
Yeah, the reason why you put this in the sea is all the crap you normally have to pump to a treatment facility just floats back into the sea so essentially removing the whole cleaning the waste step. This is quite a clever way to desalinate I wonder how much electricity it uses vs the rolled filters (osmosis) method?
@trader0108 I think that might be true when you create the vauum in the vapour side cause of the high volume, with this system you just pressuerise the low volume water to get it to the required hight then let gravity create the vacuum. But you might be right. I hope not.
We can even do it WITHOUT vacuum pump
at first stage you close the inlet pipe of sea water, you feed the tube to the end with salted water then you open the inlet sea water, the sea water will stabilized and create a pretty good vacuum with a set of valve to harvest the fresh water.
by the way the pipe does not need to be straight, only the height of the column must be respected, it mean that you can make the installation on the ground (provided you have a cave in a cliff at +6 meters and roof clearance of 7 meters).
basically you need a heath collector, radiators of cars filed with glycol mixed, in serial black painted under glass or transparent material and exposed to the sun, that will be used as exchanger to warm the salted water inside the column.
A cold source, to improve the efficiency of the condenser .
By the way this technic can be used to extract water from very dirty water
Works on the same principle as the old US Navy survival devices, which were plastic and floated on the sea water.
What is the Rate of production on a nominal unit?
Has this gone any further? I never did make a sailboat mast version. Too many issues with scale buildup and inert gasses building up in the evacuated space..Would work in theory, but too complex in real life.
Would the vac not also boil off the the condensed fresh water and the vac prevent pumping the clearwater out. lso can this be aceived at a height of 3 0r 4 foot or is it physics and be higher than 33 foot
Has this been scaled for boat use? Seems more reliable than the current systems for sale... is it an energy efficiency factor?
They don't even pull a hard vacuum by letting a colum of water sink to somewhere else
I had the same idea. Are you still working on it ?
So many clever comments. Well done all 👏👏
Any Idea of the Kilowatts used on a monthly rate? Harming the ecosystem will have to be resolved because of the byproduct Brine . There has to be a use for this byproduct and not releasing it back into the sea.So the sea water would have isolated from returning to sea life.This could be done with man made inland salt water ponds that could be drained and brine removed before refilling.Shallow ponds would also raise the water temperatures to decrease vacuum energy used.
I like the idea of filling tube with a pump. (maybe a giant harm pump if you wanted to go that far) close the valve at the top and bottom, let the vacuum and heat be for a bit, then drain off the fresh water at the top level.
oh and that hammer pump could be storing the water at an even higher tank while desalination is going on.
If it's not a continuous process, if the collection tank has to be closed and drained periodically, then it also has to be vacuumed again. Sounds like a lot of energy being expended.
Can you use the heat from the compressor to boil the water?
might work? or at least help lower the energy use.
It might help raise the water temperature so reducing the energy used lowering the pressure
why the vacuum pipe is passing through fresh water tank, cause it will result in sucking fresh water into pump. 2nd is why fresh water pipe is vanishing at tower base and inside fresh water tank ,what it means
Faisal, Just that question occurred to me, too. I don't see how it is overcome without something that expends yet more energy to counter that vacuum.
I am curious if there happened to be just a small amount of condensation of the inside water vapor onto the "inside surfaces" of your device, then if some pathogens could then possibly travel or rather swim along this condensation-inside-water-film from the bad water to the hoped for good water. What do you think, and how could this be prevented ?
Possibly this contamination could be prevented by some type of temperature control on this device.
Trader, Good question. It seems clear that the condensate is going to have to be purified, at least by passing through an ultraviolet light field.
Chlorine. Also it's a vacuum so most bacteria wont be able to thrive there.
I want to make a minature system like this for my sailboat, using the 40' mast for elevation and just using a low power pump to get the water up there. But my design still needs an electronic salinity regulator and two pumps, one high pressure for up the mast, the other low pressue for the float chamber that has the salinity regulator. I then use cold seawater for the condenser which is recirculated to a normal solar water heater to get the water to 50C or so.
You think this could work?
33 feet of your mast will be filling water inside , are you sure your boat no problem ?
@@wawansanisamudra I would put a rubber hose down the hollow mast. This should be no problem. One hose down one hose up.
@@wawansanisamudra Salt water is not good for metal parts that need to be strong...
I am a high school science teacher and I think your invention is truly inspiring. I am currently researching various classsroom enrichment ideas and I know you environmentally friendly and innovative invention will definitely stir up the interest of the young Caribbean inner city youth I am so fortunate to educate. Can you please send me any and all instructional and design and implementation ideas you have available so that I can provide my students with a blueprint as to creative brainstorms on eco friendly city/island designs? Thank you in advance for your consideration and assistance and God bless.
Sir me distillation plant operator hu hamare industries phenoxy ethanol distil hota hai iske bare me video bana vo
Fancy. Also unnecessary, just pump the water on land and do the exact same thing with water in a tank. Pull a vacuum on the top, reduce the boiling point heat water with the sun and condense the vapors at the top of the tower.
There's no reason at all to locate the tower in the ocean. Locate it on land where you can access it easier, and sink it into a hole fed by siphon from the ocean, if you have to.
Why not just make a much shorter ( in height ) system, and add a solar powered vacuum pump that will make a much greater vacuum pressure than the pressure that this device makes, & that will thus also allow the water to boil at an even lower temperature than the boiling temperature of this device ? The cost savings for the cost of such a much shorter in height system, possibly would pay for both the cost of the extra vacuum pumps and the extra photovoltaic solar panels to power the vacuum pump.
Ammm...Explain a bit more dear i am having problem over here understanding ur method.
Can you do a better animation or something it would help!
I just spoke with a scientific expert on this subject of including a vacuum in this system, and he claims that using a vacuum will not save any overall energy, as the overall energy requirements are identical with or without using a vacuum. The energy saved in heat generation is identical to the extra energy required to make the vacuum.
Use gravity to make the vacuum rather than an expensive to buy and run pump.
It makes more sense with using the decreasing temperature - at some point clean ice will form (on the sides) and you discard the dirty water in the middle or from between the crystals as it has a lower melting point. That's how I use freeze distillation only without the vacuum.
Another way to cut the cost of electricity would be a set of Stirling engines, heating and cooling water at different stages, recycling the energy. A combination of vacuum and those would make the trick. It may even be net-positive as you extract some thermal energy.
use a ram pump to create the vacuum needed...
Your scientific expert is mistaken.
Wooohoooooooo... who shud i kiss for thiS???! My ow myy
It's been 11 years and still this amazing method is not applied, No one gets any kisses 😁
ahahahahahahhaa
Cancer music
Uhmm? Did an adult review this video prior to release? Why the horrible intrusive music while we are trying to listen and be educated. Best of luck, but this appears to be a rather awful format!
That's a terrible design.
Do you really....... really have to have that stupid music playing all of the time????