EP1928792A1

EP1928792A1 - A pool chlorinator

Info

Publication number: EP1928792A1
Application number: EP06774844A
Authority: EP
Inventors: James Wesley Bess; William Leslie Stephen Smith
Original assignee: Poolrite Equipment Pty Ltd
Current assignee: Poolrite Equipment Pty Ltd
Priority date: 2005-08-22
Filing date: 2006-08-22
Publication date: 2008-06-11
Also published as: EP1928792A4; WO2007022572A1

Abstract

An electrolytic chlorinator comprising: a housing having an inlet and an outlet, the inlet allowing aqueous solution to enter the housing and the outlet allowing aqueous solution to exit the housing; at least one metal cathode and at least one metal anode that are electrically charged, the cathode and the anode located within the housing; the metal cathode being polished wherein aqueous solution flows over at least the cathode at a velocity of between 1 to 20 feet/second.

Description

TITLE

"A POOL CHLORINATOR" FIELD OF THE INVENTION

This invention relates to an electrolytic chlorinator used in swimming pools and spas.

BACKGROUND OF THE INVENTION

Electrolytic chlorinators have evolved to overcome the problems associated with chemical dosing of swimming pools, spas and the like to prevent the accumulation growth of algae and bacteria therein. The process of dissolving relatively small quantities of sodium based chloride salts in a body of water allows production of high levels of hypochlorite ions via an electrolytic chlorinator, this chlorinator with other essential chemicals such as hydrochloric acid to adjust water pH, bicarbonate of soda to act as a pH buffer, and soluble calcium salts are essential to maintain a total dissolved solids balance on pool water chemistry to reduce leaching from concrete or plaster pool wall surfaces. For the average domestic pool owner, careful and frequent pool chemistry maintenance was seen as burdensome with the result that, for example a low chlorine level would be responded to by overdosing with chlorine giving rise to very large variations in pool chemical concentrations either side of an optimum value.

The advent of electrolytic chlorinators has allowed a low level of sodium chloride dissolved in the pool or spa water to permit sodium hypochlorite generation in an electrolytic cell in an aqueous solvent on a regular cycle thereby avoiding large variations in chlorine concentration. These electrolytic cells typically included spaced electrodes comprising at least one cathode and at least one anode fabricated from flat or expanded sheet titanium, the anode and cathode further including a catalytic coating including rare earth metals such as ruthenium, platinum, palladium, niobium and iridium. Prior art pool and spa chlorinators typically comprised "in-line" and "in-pool" electrolytic cells.

In line cells were usually plumbed into the return line between the filtration system and the pool and were designed to operate only when the pool filter pump was operating to circulate water through the cell. Because their duty cycle was limited to the duration of the filtration system operation, in-line cells are generally designed as high capacity chlorine generators and typically operate at a voltage of from 24-32 volts and a current density of from 300-400 amps/m². Prior art "in-line" chlorinators are described in United States Patents Nos 4472256, 4808290, 4861451 , 5221451 , 5460706 and 6059942.

"In-pool" type chlorinators are described in Australian Patent No 569026, United States Patent No 4997540 and United States Patent No 5228964.

These "in-pool type chlorinators are mounted within a swimming pool submerged under water or are directly plumbed to the pool interior independent of the filtration system. With the exception of United State Patent No 5228964 which discloses an electric pump for circulation of electrolyte through the cell, each of the other prior art "in-pool" type systems relies upon convection currents created by hydrogen gas generation at the cathode(s) and chlorine gas that reacts immediately with the sodium ion to form sodium hypochlorite, generated at the anode(s) within the hollow cell interior.

While generally effective for their intended purpose, these prior art electrolytic chlorinators suffered from a progressive loss in electrical efficiency due to the plating out on the cathode of dissolved alkali metal salts, particularly calcium carbonate. Full current reversal during electrochlorinator operation is performed to remove these calcareous deposits or the electrolyzer is removed from service as frequently as necessary for regular cleaning with weak hydrochloric acid to remove the built up scale.

Of more recent times it has been proposed to provide chlorinator cell circuitry which permits a self cleaning function by periodic reversal of the current the difference here is that electrolysis current functions at 300-400 a/m2 vs. polarity reversal function at microamps/m2 between the electrodes. United States Patent No 4997540 describes current reversal in an "in-pool" chlorinator cell and United States Publication No. 2003/0024809 described current reversal in an in-line chlorinator cell.

With the advent of reverse current "self cleaning" electrolytic chlorine cells, it has been noted that the service life of the electrode assembly is often less than the prior art non-self cleaning electrode assemblies and this necessitates an expensive replacement process for the pool owner and usually some pro-rata warranty compensation by the cell manufacturer. It was initially considered that an electrical "shock" induced by instantaneous current reversal would control or remove deposits.

In order for the reverse current chlorinators to operate, the rare earth metal catalytic coatings must be placed over both the cathode and the anode. Hence, the electrolytic cell chlorinators that utilise reverse current are costly as they must use cathodes and anodes that both incorporate rare earth metal catalytic coatings which are expensive. Further, as electrical "shock" induced by instantaneous current reversal causes passivation of many rare earth metal catalytic coatings on the titanium electrodes providing only a very limited choice of rare earth metal catalytic coatings that can be used in reverse current electrolytic cells. OBJECT OF THE INVENTION

It is an object of the invention to overcome or alleviate one or more of the above disadvantages or provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION In one form, although not necessarily the broadest or only form, the invention resides in an electrolytic chlorinator comprising: a housing having an inlet and an outlet, the inlet allowing aqueous solution to enter the housing and the outlet allowing aqueous solution to exit the housing; at least one metal cathode and at least one metal anode that are electrically charged, the cathode and the anode located within the housing; the metal cathode being polished wherein aqueous solution flows over at least the cathode at a velocity of between 1 to 20 feet/second.

Preferably, the velocity of the aqueous solution is between 2 and 15 feet/second. More preferably, the velocity of the aqueous solution is between 3 and 12 feet/second. Even more preferably, the velocity of the aqueous solution is between 5 and 11 feet/second.

The cathode is preferably a flat plate. The anode is preferably a mesh plate or a flat plate. The cathode is preferably corrosion resistant. The cathode may be made from a nickel alloy. The cathode may be made from nickel chrome alloys such as Alloy 600 or Alloy 601. Alternatively, the cathode may be made from nickel chrome iron molybdenum alloy such as Alloy 825 or Alloy 20. Still alternatively, the cathode may be made from nickel chrome molybdenum alloys such as Alloy 625, Alloy C276 or Alloy 22.

Preferably the cathode is a metal whose chemical composition by weight percent contains Nickel 57% ± 2.85 %; Cobalt 2.5% ± 0.125%; Chromium 16% ± 0.8%; Tungsten 4% ± 0.2% and Iron 5 ± 0.35%.

More preferably the cathode is a metal whose chemical composition by weight percent contains Nickel 57%; Cobalt 2.5%; Chromium 16%; Tungsten 4%; Iron 5 ± 0.35%; Silicon up to 0.08%; Manganese up to 1 % and Carbon up to 0.01 %.

Most preferably, the cathode is made from Hastelloy C-276 Alloy. The cathode may be electro polished or mechanically polished.

The polishing may be performed to at least Ra 10 micron. Preferably, the polishing is performed to at least Ra 1 micro.

More preferably, the polishing is performed to at least Ra 0.1 micron. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying drawings in which: FIG. 1 is a side view of an electrolytic chlorinator according to an embodiment of the invention;

FIG. 2 is a side view the electrodes as shown in FIG. 1 ; and

FIG. 3 is a top view the electrodes as shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG 1 shows a side view of an electrolytic chlorinator 10 for a swimming pool or spa. The electrolytic chlorinator 10 includes a housing 20 and an electrolytic cartridge 30.

The housing 20 is substantially cylindrical in shape and has an open end 21. A housing thread 22 is located on the outside of the housing

20 adjacent the open end 21. An end cap 40 is located within the open end of the housing 20. The end cap 40 has two electrode holes 41 that extend through the end cap 40. A threaded sealing ring 52 is located over the end cap 40 and is screwed onto housing thread 22 located on the housing 20 to hold the end cap 40 securely to the end of the housing 20 and to seal, the housing 20.

The housing 20 also has an inlet 23 and an outlet 24. The inlet 23 is connected to a pump (not shown) that pumps water into the housing 20 through the inlet that is expelled out the outlet 24. The diameter of the inlet 23 and the outlet 24 are typically of the same size.

The electrolytic cartridge 30 includes a cartridge body 31 that substantially surrounds a series of electrodes in the form of an anode assembly 50 and a cathode assembly 60 shown in more detail in FIGS. 2 and 3. The anode assembly 50 includes four mesh anode plates 51 having the dimensions of 1.0 x 50 x 200 mm. The four mesh anode plates 51 are electrically connected to each other via an anode busbar 52. An anode electrical connection assembly 53 is welded to an outer mesh anode plate located adjacent the end cap 40. The anode electrical connection assembly includes an L-shaped bar 54 welded to an electrode bolt 55. The L-shaped bar 54 is welded to an inner side of an outer mesh anode plate. The electrode bolt 55 extends through the end cap 40 and is used to electrically charge the anode. The mesh anode plates 51 are made from titanium with a coating of platinum. However, it should be appreciated that other rare metal catalysts such as ruthenium, palladium, niobium or iridium may also be used.

Further, other less expensive metal catalysts such as manganese or tin in combination with the rare earth metal catalysts may be applied.

The cathode assembly 60 includes three flat cathode plates 61 having the dimensions of 0.5 x 50 x 210 mm. The three flat cathode plates 61 are electrically connected to each other by a cathode busbar 62. A cathode electrical connection assembly 63 is connected to an outer flat cathode plate. The cathode electrical connection assembly 63 includes an L-shaped bar 64 welded to an electrode bolt 65. A titanium nut 66 and grommet seal 67 is located on the electrode bolt 65. The electrode bolt 65 extends through the end cap 40 and is used to electrically charge the cathode. Each of the flat cathode plates 51 is made from a nickel, chrome, molybdenum alloy with the proprietary name of "Hastelloy C-276". However, it should be appreciated that other types of nickel alloys and also austenitic steels may be used to produce the flat cathode plates. Each of the flat cathode plates 51 are electro polished to less than Ra 0.1 micron to minimise the deviations, pits and/or imperfections. That is, the electro polishing of the flat cathode plates increases the smoothness of the flat cathode plates.

The anode plates 51 and cathode plates 61 are located within the cartridge body 31. The cartridge body 31 is formed from an upper part 32 and a lower part 33 that are joined together. Each of the upper part 32 and lower part 33 has a series of longitudinally extending grooves (not shown). The cathode plates 61 and anode plates 51 are located within respective grooves and are sandwiched between the upper part 32 and the lower part 33 to hold them in position. The upper part 32 and the lower part 33 are ultrasonically welded together to hold the cathode plates 61 and anode plates 51.

A longitudinal channel 34 is formed within the cartridge body 31 to allow for the passage of water through the housing 20. A roof 35 of the upper part 32 of the cartridge body 31 is curved and has the same diameter as the inside of the housing 20. A series of fins 36 extend around the cartridge body 31 and are also curved and have the same diameter as the inside of the housing 20.

The electrolytic cartridge 30 can be removed from the housing 20 by unscrewing the sealing ring 42 from the housing 20, removing the end cap 40 from the open end 21 of the housing 20 and then sliding the electrolytic cartridge 30 out of the open end 21 of the housing 20. This enables the electrolytic cartridge 30 to be replaced or cleaned easily.

When the electrolytic cartridge 30 is placed within the housing, the fins 36 (in conjunction with the roof) seal the housing 20 between the inlet 23 and the outlet 24. Hence, when water passes into the housing 20 via the inlet 23, the water can only pass from the inlet 23 to the outlet 24 through the channel 34 formed within the cartridge body 31. By knowing the flow rate and velocity of the water being pumped out of the pump, the cross-sectional area of the channel 34 can be varied to achieve a velocity.

In use, a current is applied to the electrode bolt to produce electrolysis using the cathode and anode to cause chlorine to be released into the water in a manner that is well known in the art. The polarizing voltage is applied when using reverse polarity i.e., a reversal of microamps/m2.

The velocity of the water that passes over the cathode plates 61 and anode plates 51 is between 7 to 9 feet per second. The increase in velocity of the water through the channel 34 is achieved by the cross- sectional area of the channel being substantially smaller than a diameter of the housing causing the velocity of the water to be increased after it passes through the inlet 23.

The electrolytic chlorinator 10 provides the distinct advantage of reduced cleaning frequency. This is due to the polishing of the cathode, the cathode being a flat plate and the increased velocity of the water across the cathode. This reduces the build up of scale (such as calcium carbonate or calcium hydroxide or magnesium hydroxide) on the cathode plates 61 and hence cleaning can be performed less frequently.

Further, it is envisaged that the application of microamps/m2 will perform the same function as reversing the current when applied to alloy cathodes that have a mirror surface. That is, the cathodes have been polished. When utilising these mirror finish cathodes and applying a polarity reversal of microamps/m2 cathode, deposit formation on the cathode is reduced. In this condition precious metal anode coatings unable to tolerate 300-400 amps/m2 current reversal conditions may be utilised. These additional coatings provide an excellent life span when operating in a reverse polarity (microamps/m2) environment.

Still further, the metal used for the cathode is substantially cheaper than that required if the electrolytic chlorinatorwas a reverse current type making the electrolytic chlorinator 10 less expensive to manufacture. Still further, as the electrolytic chlorinator 10 has a single high forward operating current path, the variety of catalytic coatings that can be placed on the anode plates are greater in number as there is less passivation of the rare earth metal catalytic coatings where very low polarizing voltages and currents are applied to the cathode plates. Yet still further, it is envisaged that the construction of the housing with the removable cartridge having a channel produces a less turbulent flow past the anode plates and the cathode plates than in prior art electrolytic chlorinators.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention.

Claims

CLAIMS:

1. An electrolytic chlorinator comprising: a housing having an inlet and an outlet, the inlet allowing aqueous solution to enter the housing and the outlet allowing aqueous solution to exit the housing; at least one metal cathode and at least one metal anode that are electrically charged, the cathode and the anode located within the housing; the metal cathode being polished wherein aqueous solution flows over at least the cathode at a velocity of between 1 to 20 feet/second.

2. The electrolytic chlorinator of claim 1 wherein the velocity of the aqueous solution is between 2 and 15 feet/second.

3. The electrolytic chlorinator of claim 1 wherein the velocity of the aqueous solution is between 3 and 12 feet/second.

4. The electrolytic chlorinator of claim 1 wherein the velocity of the aqueous solution is between 5 and 11 feet/second.

5. The electrolytic chlorinator of claim 1 wherein the cathode is a flat plate.

6. The electrolytic chlorinator of claim 1 wherein the anode is a mesh plate or a flat plate.

7. The electrolytic chlorinator of claim 1 wherein the cathode is corrosion resistant.

8. The electrolytic chlorinator of claim 1 wherein the cathode is made from a nickel alloy.

9. The electrolytic chlorinator of claim 1 wherein the cathode is made a nickel chrome alloy.

10. The electrolytic chlorinator of claim 1 wherein the cathode is made from a nickel chrome iron molybdenum alloy.

11. The electrolytic chlorinator of claim 1 wherein the cathode is made from a nickel chrome molybdenum alloy.

12. The electrolytic chlorinator of claim 1 wherein the cathode is a metal whose chemical composition by weight percent contains Nickel 57% ± 2.85 %; Cobalt 2.5% ± 0.125%; Chromium 16% ± 0.8%; Tungsten 4% ± 0.2% and Iron 5 ± 0.35%.

13. The electrolytic chlorinator of claim 1 wherein the cathode is a metal whose chemical composition by weight percent contains Nickel 57%; Cobalt

2.5%; Chromium 16%; Tungsten 4%; Iron 5 ± 0.35%; Silicon up to 0.08%; Manganese up to 1% and Carbon up to 0.01%.

14. The electrolytic chlorinator of claim 1 wherein the cathode is made from Hastelloy C-276 Alloy.

15. The electrolytic chlorinator of claim 1 wherein the cathode is electro polished or mechanically polished.

16. The electrolytic chlorinator of claim 1 wherein the polishing is performed to at least Ra 10 micron.

17. The electrolytic chlorinator of claim 1 wherein the polishing is performed to at least Ra 1 micro.

18. The electrolytic chlorinator of claim 1 wherein the polishing is performed to at least Ra 0.1 micron.

19. The electrolytic chlorinator of claim 1 wherein there are a series of alternating anode and cathode plates.

20. The electrolytic chlorinator of claim 19 wherein the another plates and cathode plates are located within a removable cartridge.