Patent Application
20050127005
1. Field
The invention is in the field of ion exchange.
2. State of the Art
Ion exchange resins are used in numerous ion exchange processes, such as water softening and water desalinization. The process works by passing material to be treated over or through a bed of the ion exchange resin. As the material contacts the ion exchange resin, particular ions to be removed from the material bind to the resin. The result is that the treated material leaving the ion exchange apparatus has a lesser amount of the particular ionic components than the material entering the apparatus. During treatment, the ion exchange resin becomes loaded with the ions binding to the resin. As the resin becomes more loaded with these bound components, the effectiveness of the ion exchange drops. Eventually the resin becomes so saturated with the ions from the material that the ion exchange process becomes ineffective, the ions to be removed are not removed, and the resin is considered “spent.” The “spent” resin has to be regenerated, usually by elution, in order to restore the resin's capacity to again bind the desired components before further ion exchange can take place.
For Example, ion exchange columns are used for water softening. Hard water has Ca++ and Mg++ ions therein which make it “hard.” A typical water softener uses NaCl to remove the Ca++ and Mg++ ions from the water by passing the water through a bed of ion exchange resin where the resin carries Na ions. The resin exchanges its Na ion for the Ca and Mg ions in the water. After performing this operation for a certain amount of time, the resin becomes loaded with Ca++ and Mg++ ions and its Na ions become depleted. The resin is so full of ions taken from the treated material and depleted in its own ionic component that ion exchange can no longer occur. Once this happens either new resin must be used or the resin must be regenerated before the apparatus will function again.
Regeneration of the “spent” resin involves treating the “spent” resin with a regenerant, generally sodium chloride, hydrochloric acid, or sulfuric acid, which reverses the process and exchanges the ions which have been removed from the material treated and built up on the resin with ions of the type originally on the resin. Thus, for the water softener example, the spent resin is treated with NaCl in the form of strong salt water so that the exchange process is reversed and the Ca++ and Mg++ ions on the spent resin are removed from the resin and replaced with Na ions. The effectiveness of the regeneration process depends upon the strength and amount of regenerant used. However, regenerants have a cost which adds to the cost of the ion exchange process and have to be balanced with overall process costs. Thus, the regenerant is carefully used in volume and weight to provide an effective resin capacity for the process concerned along with most effective overall process costs.
Since the effectiveness of an ion exchange process is tied to the ion exchange capacity of the resin, i.e., the capacity of the resin to exchange and thereby remove the ions to be removed from the material being treated before the resin becomes spent and has to be regenerated, increasing the ion exchange capacity of the resin in a given ion exchange process in an economic manner will increase the effectiveness of that ion exchange process.
According to the invention, the ion exchange capacity of ion exchange resin can be increased by applying a magnetic field to the resin while the ion exchange procedure takes place. The increased resin capacity makes the resin more efficient as more material can be treated by the resin before the resin requires regeneration. The apparatus needed is simple in design and only requires that a magnetic field be applied to any given nonmagnetic ion exchange column, such as ion exchange columns made of plastic or glass. The ion exchange column is used to hold the resin as it contacts the material to be treated. A variety of magnetic devices may be used and have been used successfully including stationary magnets taped to the ion exchange column, magnets that rotate around the column, and an A.C. and/or pulsed D.C. current applied to a wire wrapped around the ion exchange column. A rod of magnetic material, such as cast iron, can be placed in the column to concentrate the magnetic field generated in the wire coil around the column. Some minimal magnetic strength appears to be required before a practical increase in ion exchange capacity is observed, but currently this minimum level is unknown.
In the accompanying drawings, which show the best mode currently contemplated for carrying out the invention:
Ion exchange columns are used in a variety of processes, such as water softening and water desalinization. Ion exchange works by passing material that needs to be treated, like water, over a resin. The resin exchanges its ionic component with an ion in the material to be treated. For example, a typical water softener uses NaCl to remove Ca++ and Mg++ from the water by exchanging its Na ion for the Ca and Mg ions in the water. After performing this operation for a certain amount of time, the resin becomes loaded. The resin is so full of ions taken from the treated material and depleted in its own ionic component that ion exchange can no longer occur. Once this happens either new resin must be used or the resin must be regenerated before the apparatus will function again.
The inventor has found that applying a magnetic field to the ion exchange column during the exchange process will increase the binding capacity of the resin, increasing the amount of time the ion exchange column can operate before requiring regeneration. The invention comprises applying a magnetic field to the resin in the ion exchange column during the ion exchange procedure. The invention works with both cathodic and anodic resins. The invention can also increase the capacity of both types of resins when combined into a single mixed bed apparatus. The magnetic field can be generated with an electromagnet or with permanent magnets. An electromagnet can be formed by wrapping magnet or other wire around a nonmagnetic ion exchange column, such as a plastic or glass tube containing ion exchange resin, or by placing permanent magnets around a nonmagnetic ion exchange column. The permanent magnets may be secured to the column in stationary manner or may be mounted for rotation around the column.
A minimum threshold of magnetic force appears to be needed, but the exact level of this force has not been determined. Several initial preliminary tests indicated no benefit from a small magnetic field surrounding the resin in an ion exchange column during the ion exchange procedure. In one test, a twelve inch long, {fraction (1/16)} inch thick, two inch inside diameter steel tube was lined with five sets, ten total, small permanent magnets. A one inch diameter acrylic tube filled with cation resin was inserted into the metal tube with the magnets between the metal tube and the acrylic tube. When sea water was passed through the resin, no increase in cation bonding capacity was observed.
In a second test, the steel tube of the first test, with interior permanent magnets still in place, was wrapped with high temperature resistant paper. The paper was then wrapped with 5000 wraps of twenty eight gage copper magnet wire over its twelve inch length. The wire was held by two four inch diameter wood discs at each end of the tube. The wire was insulated with wraps of high temperature resistive insulating tape. The ends of the magnet wire were connected to a plug to be plugged into a 110 volt AC outlet. A fifteen inch long, one and five eights inch diameter acrylic tube was inserted into the steel tube and filled with IR-120 which is a cation resin from Rohm & Haas. Once again, no beneficial increase of the resin's capacity was observed when sea water was run through the apparatus with the coil plugged into a 110 volt AC outlet. Use of a rectifier to provide 110 volt and 220 volt DC was also of no use. Additional tests with wire wrapped around a metal tube were also unsuccessful, probably because any magnetic field generated by the wire windings was blocked by the metal tube from influencing the ion exchange column within the metal tube.
In order to further test the idea of increasing the capacity of ion exchange resin by providing a magnetic field around the resin during the ion exchange process, a test apparatus as shown in
Ion exchange resin 30 fills ion exchange column 18, preferable no more than about half way, but extends through the height of the wire windings 12. A screen or mesh material 31, such as a nylon mesh, covers hole 23 to prevent the ion exchange resin from flowing out of the bottom of the column. The screen or mesh material 31 may be positioned over the end of stopper 22 and sandwiched between the sides of the stopper and the column to hold it in place, or, as illustrated, a washer 32 may be secured to the top of stopper 22 by screws 33 to secure the screen or mesh material in place over hole 23.
A core 34 of nonmagnetizable magnetic material, such as cast iron, is positioned in the center of ion exchange column 18 to extend through the ion exchange resin 30. Core 34 is centered in the bottom of the ion exchange column by a nonmagnetic rod 35 extending through core 34 and at the top of the core by either a similar nomagnetic rod, or if the top of the rod is above the level of the resin, by a centering disc 36. A centering rod could be used at the top in this case also, but the centering disc, which is perforated and positioned above the top of the resin bed, serves the additional purpose of distributing the material added to the column for treatment and reducing turbulence at the top of the bed when the material is added. When a centering disc is not used, such as when the top of the rod is in the resin, a similar disc is generally provided above the resin to reduce turbulence at the top of the bed when the material is added. With the embodiment illustrated, the ion exchange column 18 can be inserted in the tube 10 having the windings 12, and the ion exchange column can be removed and easily replaced when desired.
Rather than a separate tube 10 for the windings 12, windings 12 could be placed directly around the ion exchange column 18.
The dimensions of the apparatus shown in
When power is connected between the coil leads 15, current flows through the coils 12 and a magnetic field is generated. The magnetic field extends through the resin 30 within the coils 12 with the metal core 34 concentrating the magnetic field in the resin bed. Thus, the resin in the resin bed is under the influence of a magnetic field. The coils can be energized by various signals from the standard 110 volt, sixty Hertz AC signal from a wall outlet to various other AC and DC signals from a variety of signal generators.
A signal generation circuit used to vary the signal applied to electromagnet L,
Various experiments have been performed with the apparatus shown in
An apparatus substantially as shown in
For the second run, the coil made up of 10,000 wraps of number twenty three magnet wire around a two inch outer diameter pyrex tube, was energized with the function generator of the circuitry of
The third run was similar to the first run without the metal bar and without any magnetic field generated by the coil. However, 300 grams of Dow HCR cation resin was used rather than the 300 grams of Rohm and Haas IR-120 resin, and the sample treated was San Francisco ocean water rather than San Francisco Bay water. The regeneration time prior to the sample run was nineteen minutes with a fourteen minute rinse. The results were about the same as the first run with the test showing between nine and ten cups of sample could be treated by the resin in the column before the resin was exhausted. This result is shown as the third bar, labeled 103, in the graph of
The fourth run used the coil made up of 10,000 wraps of number twenty three magnet wire around a two inch outer diameter pyrex tube as used in run two. The coil was energized with the function generator of the circuitry of
The fifth run was the same as the fourth run except that the resin was no longer new. It was regenerated over about twenty five minutes with a rinse of about nineteen minutes. The first seventy five ml. of effluent was discarded prior to starting testing to allow the rinse water at the start of the run to flow out of the column and ensure that the sample was being tested. This test run showed that the resin became exhausted between about eleven and eleven and one half cups of sample, slightly less than the previous run. This is shown by the fifth bar, labeled 105, in the graph of
The sixth run was the same as the fifth run, but with a 500 hertz sine wave applied to the coil. The resin was regenerated over about twenty one minutes with a rinse of about twenty two minutes. This test run showed that the resin became exhausted at about eleven cups of sample, about the same as run five. This is shown by the sixth bar, labeled 106, in the graph of
The seventh run was the same as the sixth run, but with a 550 hertz sine wave applied to the coil. This test run showed that the resin became exhausted at about ten to ten and one half cups of sample, less than that for run six. This is shown by the seventh bar, labeled 107, in the graph of
The eighth run was the same as the sixth run, but with a 600 hertz sine wave applied to the coil. The resin was regenerated over about thirty minutes with a rinse of about twenty minutes. This test run showed that the resin became exhausted at about ten and one half to eleven cups of sample. This is shown by the eighth bar, labeled 108, in the graph of
The ninth run was similar to the eighth run using the equivalent Dow HCR cation resin, but with a twelve and three quarter inch long, seven sixteenth inch round rod rather than the flat rod in the resin bed. Backwash was done twice. Regeneration took about twenty five minutes and rinse took about nineteen minutes. The results were the same as for run eight indicating no difference between the round and flat rods. This is shown by the ninth bar, labeled 109, in the graph of
The tenth run was similar to the ninth run but with the flat cast iron rod of previous runs and using a 650 hertz sine wave applied to the coil. Regeneration took about twenty two minutes and rinse took about twenty four minutes. This test run showed that the resin became exhausted at about thirteen to thirteen and one half cups of sample. This is shown by the tenth bar, labeled 110, in the graph of
The eleventh run was the same as the tenth run with a regeneration time of about twenty minutes and rinse time of about twenty two minutes. This test run showed that the resin became exhausted at about thirteen to thirteen and one half cups of sample, the same as with the previous run. This is shown by the eleventh bar, labeled 111, in the graph of
The twelfth run used a one and five eights inch inside diameter pyrex column with a 675 hertz sine wave applied to the coil. Regeneration took about twenty two minutes and rinse took about twenty two minutes. This test run showed that the resin became exhausted at about fourteen to fourteen and one half cups of sample. This is shown by the twelfth bar, labeled 112, in the graph of
The thirteenth run was the same as the twelfth run with a 675 hertz sine wave applied to the coil. Regeneration took about thirty minutes and rinse took about eighteen minutes. This test run showed that the resin became exhausted at about fourteen to fourteen and one half cups of sample, the same as for the prior run. This is shown by the thirteenth bar, labeled 113, in the graph of
The fourteenth run was the same as the thirteenth but with a 700 hertz sine wave applied to the coil. Regeneration took about twenty four minutes and rinse took about seventeen minutes. This test run showed that the resin became exhausted at about thirteen to thirteen and one half cups of sample. This is shown by the fourteenth bar, labeled 114, in the graph of
The fifteenth run was the same as the fourteenth. Regeneration took about twenty three minutes and rinse took about twenty seven minutes. This test run showed that the resin became exhausted at about thirteen and one half to about fourteen cups of sample. This is shown by the fifteenth bar, labeled 115, in the graph of
The sixteenth run was the same as the fifteenth but with a 750 hertz sine wave applied to the coil. Regeneration took about twenty minutes and rinse took about twenty three minutes. This test run showed that the resin became exhausted at about thirteen and one half to about fourteen cups of sample. This is shown by the sixteenth bar, labeled 116, in the graph of
The seventeenth run was the same as the sixteenth. Regeneration took about twenty five minutes and rinse took about nineteen minutes. This test run showed that the resin became exhausted at about thirteen and one half to about fourteen cups of sample. This is shown by the seventeenth bar, labeled 117, in the graph of
As indicated by the results of Example 1, the presence of an electromagnetic field around the ion exchange column and a bar of magnetic material in the resin to direct and concentrate the magnetic field in the resin, is effective to increase the ion exchange capacity of the resin. While the magnitude of the capacity increase varied with factors such as the frequency of the sine wave used to create the magnetic field, significant increases in capacity occurred at all frequencies tested. Thus, without the magnetic field present, about seventy two ounces of water could be treated with the resin. However, with the magnetic field present along with the metal bar, up to one hundred and twelve ounces of water could be treated with the same amount of resin and using the same resin regeneration procedure. This was a significant 55% increase in ion exchange capacity of the resin. The variation in regeneration and rinse times, due mainly to the nonrepeatable flow rates through the column during regeneration and rinse, did not appear to influence the results. This would be expected as the regeneration time should not matter as long as it is enough to regenerate the resin. Various other tests indicated that a sine wave appeared to work better than a square or triangle wave and that various types of metal bar could be used with about the same results.
Similar tests were performed as in Example 1 only using an anion resin instead of a cathodic one. Further, the apparatus used was that shown in
Similar results are reached when a cation resin and an anion resin are mixed together to form a mixed bed in the column. Rohm & Haas cation IR-120 was regenerated individually and then mixed with anion Dowex 55A-OH, which had also been regenerated individually. Without the magnetic field, sixty eight ounces of San Francisco ocean water were treated before the capacity of the resins was reached. When a 675 Hz sine wave was used to create the magnetic field, ninety six ounces of water passed through before the capacity of the resin was reached. This is a significant 41% increase in capacity.
An alternate apparatus for creating a magnetic field in an ion exchange resin bed is shown in
Several test runs were made using the apparatus of
The resin filled tube was inserted into the drum holding the magnets as shown in
A further embodiment of apparatus of the invention for creating a magnetic field in an ion exchange resin bed is shown in
A forty eight inch long, four and three quarter inch inside diameter acrylic ion exchange column was filled about seventeen inches deep with three kilograms of Dow HCR resin. The regeneration and backwash used were scaled up to meet the requirements of the larger tube and larger amount of resin. Thus, three batches of 50.9 grams of thirty seven percent HCl each mixed with 250 grams of distilled water were used for regeneration and rinsed with three cups of distilled water. The tube was surrounded by eighteen curved heavy magnets taken from a direct current one horsepower motor. The magnets were fastened in place by tape 70 in positions as shown in
Whereas the invention is here illustrated and described with reference to embodiments thereof presently contemplated as the best mode of carrying out the invention in actual practice, it is to be understood that various changes may be made in adapting the invention to different embodiments without departing from the broader inventive concepts disclosed herein and comprehended by the claims that follow.
