Inexpensive Desalinizer

I just realized this idea this morning. If water is under 29 hg's (inches) of vacuum, it will boil at 75F or 24.4C.

If the vacuum is increased to 29.42 hg's of vacuum, water boils at 59F or 15C.

A pressure head 33 ft. (9.8m) tall is supposed to create such a vacuum. If so, then very little energy would be needed to desalinize or purify water. There would be 3 pressure heads at work. One would be solute or brackish water. The second would be for brine discharge and the third, of course, would be clean water.

If the self siphoning concept can work, then it could be a self powering system. If not, then 3 pumps would be needed.

This would be to ensure a controlled flow and to maintain the necessary vacuum. And since the pipes could be welded, there might be nothing to allow air into the system except for what is in the water.

To degas water, pressure heads could be filled while almost all air is vented, When the vent is closed, water could be drawn through. And then as degassing occurs, the water level on the discharge side can be allowed tolower to maintain the vacuum.

After this, degassed water could be drawn through another set of pressure heads causing it to evaporate under vacuum. And by using the mass of the water to maintain vacuum, it should be a fairly efficient system.

Since water does cool as water evaporates, the lower temperature would need to be considered. Also, for continuous operation, 2 degassing systems may be needed.

I'm kind of wonderingif someone has tried this before.

chart
http://i979.photobucket.com/albums/ae278/bessler_supporter/chart_zps341e6f74.gif

design
http://i979.photobucket.com/albums/ae278/bessler_supporter/SelfSiphoningDesalinizer_zps93e4885e.jpg

2 Answers

1. But, I thought that the recovery rate of the plant will be very low.

   1 Comment

   1. Hi Yahia, It would be. One thing this idea has helped me to understand is that under such conditions of vacuum, a normal R.O. system should be much more efficient. There are 3 basic reasons why. The first 2 are that adhesion and cohesion with water molecules should be non-factors. And what might be a great surprise is that under vacuum, water molecules should contract while being more energetic. These last 2 things should let water molecules flow through a membrane much easier. One thing that would need to be changed is that the water would need to be drawn through the membrane and this might be able to happen with a significant savings.

2. One thing I have realized is that data that was achieved to simulate conditions on Mars suggests a rate of 10L/hr per square meter. While that may not seem like much, that is with water, air and surface temperatures at 0C. Here on planet Earth and with a water temperature about 24.4C, a vacuum of 29 hg's would be needed. And because of the greater temperature variation possible between evaporated and condensed water, a much more favorable rate should be possible. This is something I plan on pursuing in the near future. It is as the scientists who did the Mars study stated, there is little data on the evaporation rate of water under vacuum. This is something I hope to make better understood. There is one give away with pressure heads and vacuum. When vacuum nears 29 hg's (28.67), the boiling point of water lowers less as the vacuum is increased. This would be because the atmospheric gasses are becoming stretched. This would require a pressure head taller than 9.8 meters to have sufficient force to expand atmospheric gasses beyond their normal state and achieve an extreme vacuum. And if such an idea works well, the water moving through such a system would require little energy as the brine and fresh water discharges would help to ensure that sea water is drawn into the system by the vacuum desalinizing the water. Simply put, the 2 discharges would be siphoning water into the system as they drain.