Osmotic desalinization process

Details Osmotic desalinization process Osmotic desalinization process

2000-08-04

2002-05-21

Fortuna, Ana (Department: 1723)

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

C210S642000, C210S652000, C023S306000

Reexamination Certificate

active

06391205

ABSTRACT:

FIELD OF THE INVENTION
The invention pertains to the field of water recovery from aqueous solutions. More particularly, the invention pertains to the desalinization of a saline solution.
BACKGROUND OF THE INVENTION
The economically and energetically practical desalinization of saline solutions has long been a goal of organized society. In fact, there are suggestions found in the Bible, and in writings by the ancient Greeks, that suggest knowledge regarding the desalting of brackish waters. The benefits of such a process are obvious and important in a world with both a rapidly increasing population and a relatively static fresh water supply. However, it was not until the nineteenth century in England that the first official studies were made into the possibility and practicality of desalinization and ion exchange.
Milestones in the scientific approach to desalinization include the realization by the German chemist Eichorn, in 1858, that ion exchange reactions are reversible ones. By 1905 German scientist Gans developed a process of softening water on a commercial basis using cation exchange materials. In 1935 two English chemists, Adams and Holmes, produced an ion exchanger. The cation exchanger used was a phenolformaldehyde condensation product and the anion exchanger was a condensation product of polyamines and formaldehyde. These products made possible the near complete removal of all ions, including aqueous sodium chloride (“NaCl
(aq)
”), from water. However, the anion exchanger was unable to remove weak alkaline or silica based acids, and the important chemical species to accomplish the ion reduction were both expensive to produce and difficult to handle.
More recently, various desalinization systems have relied upon phase transformations, electrodialysis, or reverse osmosis techniques which are energetically expensive processes. A semi-permeable membrane, like the cell wall of a bladder, is selective about what it allows through it, generally allowing small molecules like water to pass easily but preventing the passage of many other compounds. With the presence of two solutions, each containing a different concentration of dissolved compounds on either side of the barrier, water will typically move from the side of the more dilute solution to the more concentrated solution. Eventually, osmotic pressure will counter the diffusion process exactly, and equilibrium will form. The process of reverse osmosis, first described by a French scientist in 1748, forces a net flow of water molecules from an aqueous solution with a greater concentration of compounds present within it through a semi-permeable membrane and into a solution with a lower concentration of dissolved compounds In a relatively expensive energy step, high water pressure on the source side is used to “reverse” the natural or forward osmotic process. For example, the desalinization of brackish water typically requires operating pressures within the range of 250 to 500 psi, while seawater desalinization requires operating pressures from 800 to 1000 psi, to obtain potable water as the final product.
Other workers in the field have attempted to provide workable desalinization systems to address the long standing need for an efficient and inexpensive method for the demineralization of water. See for example, Batchelder, U.S. Pat. No. 3,171,799; Glew, U.S. Pat. No. 3,216,930; Halff, U.S. Pat. No. 3,617,547; Frank, U.S. Pat. No. 3,670,897; and Yaeli, U.S. Pat. No. 5,098,575. However, none suggest the type of osmolar and thermal manipulations provided by the instant invention.
Through the use of the osmosis techniques and apparati of the invention described herein, virtually unlimited amounts of water can be made potable for a variety of uses including agricultural uses, commercial uses, and as a source of drinking water. More importantly, the creation of potable water through desalinization can essentially “drought-proof” a given population, region, or industry.
SUMMARY OF THE INVENTION
The present invention teaches a method and apparatus for recovering water from aqueous solutions. In a preferred embodiment, the present invention teaches a forward osmotic process to create potable water from a saline solution through the manipulation of thermal and osmolar conditions of multiple solutions in a series of reactions which result in the passage of H
2
O from one solution to another through solvent transfer means, such as semi-permeable membranes.
The invention relates to an osmotic process or method for the extraction of a solvent from a first solution, having a first solute difficult to separate from the solvent, by passing said solvent through a series of intermediate solutions comprising the steps or drawing the first solution into a first heating means to heat the first solution; drawing the first solution into a first chamber that is divided by a first solvent transfer means from a saturated second solution having a second solute in a second chamber; subjecting the first solution to “natural” or forward osmosis by means of the first solvent transfer means, in opposition to the second solution such that a net osmotic flow of the solvent takes place across the first solvent transfer means and into the second solution thereby increasing the volume of the second solution; drawing the second solution from the second chamber into a cooling means to cool the second solution; drawing the second solution into a third chamber that is divided by a second solvent transfer means from a third solution having a third solute in a fourth chamber; subjecting the second solution to forward osmosis by means of the second solvent transfer means, in opposition to the third solution such that a net osmotic flow of solvent takes place across the second solvent transfer means and into the third solution thereby increasing the volume of the third solution; drawing the third solution from the fourth chamber into a second heating means to heat the third solution; drawing the third solution into a fifth chamber to provide for removal of any remaining third solute; and collecting the third solution, now diluted, for use. Optionally, the fifth chamber can be divided by a third solvent transfer means from a fourth solution having a fourth solute in a sixth chamber. Prior to collecting the third solution, it would be subjected to forward osmosis by means of the third solvent transfer means, in opposition to the fourth solution such that a net osmotic flow of the solvent takes place across the third solvent transfer means and into the fourth solution, increasing its volume and diluting it. The fourth solution would then be collected, now diluted, for use.
In this invention the flow of H
2
O from one opposing solution to another is such that there is a net osmotic flow of H
2
O from a saline solution, such as seawater, through a series of intermediate solutions to an ending solution. The intermediate solutions, which are subjected to thermal and osmolar manipulation, are used to generate a final solution with a very low concentration of an acceptable or desirable end-product solute. The process takes advantage of the solutes having highly temperature dependent solubilities, such as KNO
3(s)
and SO
2(g)
, as well as the relatively temperature indifferent solubility of NaCl
(aq)
, the primary solute present in seawater.
In general, the first solution is a saline solution and the second and third solutions are aqueous solutions of salts (i.e., water is the solvent and the salt is the solute) having temperature dependent solubility. The solubility of the second solute is directly related to temperature while the solubility of the third solute is inversely related to the temperature. A fourth, optional solution contains one or more desired additives that will be introduced into the final product. Typically the first solution is seawater (NaCl
(aq)
, the second solution is a saturated KNO
3
solution, the third solution is a saturated SO
2
solution at 15 atm partial pressure to insure sufficient concentration of the SO
2
solute, and the fourth solution is

Affiliated with

Also associated with

Rating

Osmotic desalinization process does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Osmotic desalinization process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Osmotic desalinization process will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2888036