System and method for producing a hypochlorous acid disinfectant solution

Abstract

The invention relates to a system for producing a disinfectant solution comprising: - a dilution tank (300) including a water inlet (302) allowing filling with water, - an electrolyser (100) arranged below the tank (300) and including: - an electrolysis enclosure (110) storing alkali chloride in solid form, - a set of electrodes (120), and - a duct (200) connecting the enclosure and the tank, and wherein: - filling the tank results in filling the enclosure by the duct in order to prepare an aqueous solution containing chloride ions by dissolving a portion of the alkali chloride; and - electrolysing the aqueous solution in the enclosure produces hypochlorous acid, at least a portion of which migrates from the enclosure to the tank via the duct, the at least one portion of the hypochlorous acid that migrated diluting in the water present in the tank so as to form the disinfectant solution.

Description

Description Title: System and method for producing a hypochlorous acid disinfectant solution [Technical field. [1] The invention relates to a system for producing a disinfectant solution containing hypochlorous acid. The invention also relates to a method using this system. [2] The field of the invention is that of the manufacture and design of apparatus and systems for the electrochemical production of hypochlorous acid. The invention finds particular application in the field of disinfection of, for example, but not limited to, water, air, hard or soft surfaces, plant, animal or human surfaces, surfaces of medical devices. State of the art. [3] Hypochlorous acid (CAS No. 7790-92-3) is a weak inorganic acid with the formula HOCI. It partially dissociates in water to produce the hypochlorite ion (OCI) according to the reaction of equation 1: HOCI(aq) H + (aq> + OCI'(aq) pKa of approximately 7.5 (1) [4] In aqueous solution, the distribution of the two chlorine species (HOCI / OCr) depends on the pH of the water as shown in the attached figure 1. [5] As can be seen from Figure 1, hypochlorous acid is the predominant species at pH < 7.6 and the hypochlorite form becomes predominant at pH > 7.6 (alkaline pH). At pH values ​​below 3.5, chlorine gas begins to form. To maintain the hypochlorous acid (HOCI) solution in a stable form, maximize its antimicrobial activities and minimize unwanted side products, the pH should preferably be maintained between 3.5 and 7.5. [6] Hypochlorous acid (HOCI) is, moreover, a major bactericidal compound of innate immunity. It is produced naturally in mammals by white blood cells to fight infections. It has properties Germicidal against a wide range of microorganisms (bacteria, viruses, fungi, etc.). Compared to sodium hypochlorite (the main component of bleach), which is often used as a sterilizing agent, hypochlorous acid is said to be 80 to 120 times more effective while being less irritating to the skin. [7] Hypochlorous acid has many uses such as in water treatment, hygiene and food safety, sanitation of all types of surfaces, objects or food, as well as in pharmacy and medicine, particularly for wound care and skin disinfection. It should be noted that hypochlorous acid is authorized by the United States Food and Drug Administration (FDA) as a biocidal product. Furthermore, the European Commission approved, in July 2021, active chlorine released from hypochlorous acid (EC No. 232-232-5) as an active substance in biocidal products used for human hygiene. The recent outbreak of the novel coronavirus Covid-19 has not only led to a shortage of alcohol-based disinfection products on the market, but has also demonstrated the importance of hypochlorous acid in the disinfection of places likely to be contaminated by the coronavirus Covid-19.As a result, there is now a growing demand for hypochlorous acid-based disinfectant solutions in a wide variety of application sectors (e.g. water treatment, food processing, cosmetics, medicine, etc.). [8] Various systems and methods for preparing disinfectant solutions containing hypochlorous acid have been proposed in the prior art. Among the known systems and methods, the following may be cited, by way of example: - the hydrolysis of chlorine gas according to the reaction of equation 2 below, - the acidification of hypochlorite ion according to the reaction of equation 3 below, - the electrolysis of an aqueous solution of sodium chloride according to the reactions of equations 4-6 below. Cl2(g) + H2O(|) HOCI(aq) + H + (aq) + Cl'(aq) (2) OCI (aq) + H + (aq) HOCI(aq) (3) 2CI'(aq) -> Cl2(g) + 2e' (4) 2H2O(i) + 2e" H2(g) + 20H'(aq) (5) Cl2(g) + 20H'(aq) —> OCI'(aq) + Cl'(aq) + H2O ) (6) [9] The process according to equation 2 is rapid and effective for preparing disinfectant solutions containing hypochlorous acid. However, it is very little used because of the risks inherent in handling chlorine gas and the dangers associated with its storage.

[0010] The process according to equation 3 involves acidifying an aqueous solution of a hypochlorite salt, such as calcium or sodium hypochlorite, with an aqueous solution of an acidifier, such as hydrochloric acid, to obtain a disinfectant solution containing hypochlorous acid. However, this process requires very precise control of pH and temperature during the acidification process to prevent or reduce the generation of toxic chlorine gas. In addition, this process requires the manufacture, transportation, and storage of hypochlorite salts and acid products, which are corrosive chemicals.

[0011] The process according to the reaction of equations 4-6 is the most widely used for the production of disinfectant solutions containing hypochlorous acid. This process does not generally require the presence, in the water, of chemicals other than an alkali chloride such as sodium or potassium chloride. In particular, this process consists of supplying a tank or enclosure equipped with an electrolytic cell comprising electrodes including at least one anode and at least one cathode, with an aqueous solution containing a certain proportion of alkali chloride, in particular sodium chloride, electrolyzing this aqueous solution in order to produce an aqueous solution of hypochlorous acid, then transferring, for example by pumping, this solution of hypochlorous acid into another enclosure or tank to be diluted there with water to obtain a disinfectant solution containing hypochlorous acid.It should be noted that the reaction of equation 4 (oxidation of chloride ions) takes place at the level of at least one anode and leads to the formation of chlorine gas and that of equation 5 (reduction of water) takes place at the level of at least one cathode and leads to the generation of dihydrogen.

[0012] As a reminder, the electrolytic cells involved in the known processes exist in two categories: - The first category includes split cells which use membranes to maintain complete separation of anode and cathode products within the cells, thus, the chlorine gas produced at each anode according to the equation dissolves in water to form hypochlorous acid according to the reaction of equation 2 mentioned above. - The second category includes undivided cells that do not use membranes. In this case, the chlorine gas generated at each anode can directly react with the hydroxide anion produced at each cathode to form hypochlorite ions according to the reaction of equation 6, which hypochlorite ions can be in equilibrium with hypochlorous acid according to the reaction of equation 1 mentioned above.

[0013] The prior art electrolysis methods and systems all have one or more of the following disadvantages: - The disinfectant solutions produced are generally contaminated by significant quantities of chloride salt and / or are very dilute and / or weakly concentrated in hypochlorous acid (< 3 ppm). - They generally involve large installations and / or are relatively complex and therefore expensive. - They do not meet the user's need to be able to adapt the production of the disinfectant solution according to the desired concentration of hypochlorous acid. As mentioned above, the applications for using the disinfectant solution are multiple, it is of course desirable to give the user the possibility of choosing the concentration of hypochlorous acid that best suits the disinfection operation that he must carry out. The invention aims to overcome all or part of the aforementioned drawbacks. Another objective of the invention is to provide a system or method for producing a disinfectant solution based on hypochlorous acid which allows a user to obtain said disinfectant solution with the concentration of hypochlorous acid which is best suited to the use he wishes to do so. Yet another object of the invention is to provide such a system or method which is simple in design, easily achievable and easy to implement, on a small or large scale and which is inexpensive. Another object of the invention is to provide such a system or method which allows the user to monitor the production of said disinfectant solution in an efficient manner Presentation of the invention.

[0014] The solution proposed by the invention is a system for producing a disinfectant solution containing hypochlorous acid. This system is remarkable in that it comprises: - a dilution tank dedicated to the preparation of the disinfectant solution, which tank has a water inlet allowing the filling of said tank with water, - at least one electrolyser arranged below the dilution tank, and comprising: - an electrolysis chamber storing alkali chloride in solid form, - at least one set of electrodes comprising at least one anode and at least one cathode arranged in the electrolysis chamber, -- a conduit connecting the electrolysis chamber and the dilution tank.

[0015] This system is further remarkable in that said conduit is arranged so that filling the dilution tank with water causes the electrolysis chamber to be filled with water, to prepare an aqueous solution containing chloride ions by dissolving a portion of the alkali chloride stored in said chamber, and so that when said aqueous solution is electrolyzed in the electrolysis chamber using the set of electrodes to produce hypochlorous acid, at least a portion of the hypochlorous acid can migrate from said chamber to said tank, and can dilute in the water present in said tank in order to form the disinfectant solution.

[0016] The system for producing a disinfectant solution containing hypochlorous acid according to the present invention has many advantages, in particular that of being simple in design, easily achievable, easy to implement work, on a small or large scale and inexpensive. In addition, the system according to the present invention allows a user to obtain the disinfectant solution with the hypochlorous acid concentration that best suits the use he wishes to make of it. Indeed, the user can adjust this system so that the disinfectant solution is concentrated in hypochlorous acid with the desired free chlorine content (for example, 5 ppm, 100 ppm, 250 ppm, 1500 ppm, 3000 ppm, or more than 3000 ppm). To do this, he has at his disposal different ways to adjust the system, he can for example increase the number of electrolyzers and / or the number of sets of electrodes per electrolyzer and / or the number of electrodes per set of electrodes.It will be noted that the system according to the present invention does not comprise any transfer means, for example of the pump type, for transferring the hypochlorous acid (and / or the hypochlorite ions) generated in the electrolysis chamber from the latter to the dilution tank in which the hypochlorous acid must be mixed with water to form the disinfectant solution. It will also be noted that before the electrolysis, the dilution tank placed above the electrolysis chamber contained water, and that after the electrolysis this water was replaced by the disinfectant solution.

[0017] Other advantageous features of the invention are listed below. Each of these features may be considered alone or in combination with the remarkable features defined above, and may be the subject, where appropriate, of one or more divisional patent applications:

[0018] Advantageously, the electrolysis of the aqueous solution in the electrolysis chamber is adjusted to generate the formation of gas bubbles, so that said bubbles create turbulence capable of forcing the migration of at least part of the hypochlorous acid from the electrolysis chamber to the dilution tank via the conduit.

[0019] The at least one electrolyzer can be one or two or three or more electrolyzers.

[0020] The at least one set of electrodes may be one or two or more sets of electrodes.

[0021] Preferably, the at least one set of electrodes further comprises a plurality of bipolar electrodes interposed between an anode and a cathode of the at least one set of electrodes.

[0022] Preferably, the at least one anode, the at least one cathode and the plurality of bipolar electrodes of the at least one set of electrodes are all in the form of flat plates, parallel and regularly spaced from each other.

[0023] In an alternative embodiment, the at least one set of electrodes comprises a plurality of anodes and a plurality of cathodes, which pluralities of anodes and cathodes are in the form of flat plates arranged in parallel rows of alternating polarity.

[0024] The electrolysis chamber of the at least one electrolyser may have a capacity of at least 10 litres.

[0025] The dilution tank may further comprise means for breaking up (or reducing the size of) the bubbles of chlorine gas which may come from the electrolysis chamber of the at least one electrolyser in order to promote the dissolution of the chlorine gas in the water, said means for breaking up said bubbles of chlorine gas being arranged at the bottom of the dilution tank at least opposite the conduit putting the electrolysis chamber and the dilution tank into fluid communication.

[0026] The means for breaking up the gas bubbles may consist of at least one flat plate having perforations of a diameter sufficient to reduce the size of the gas bubbles to dimensions which promote the dissolution of the chlorine in the water.

[0027] Preferably, the perforations of the at least one plate have a diameter of less than 5 mm, preferably less than 1 mm.

[0028] In particular, the means for breaking the gas bubbles consist of several flat and perforated plates, these plates are superimposed in such a way that the perforations of one plate are offset relative to the perforations of another plate which is adjacent to it.

[0029] Advantageously, the system according to the present invention further comprises a measuring device comprising: - a sensor suitable for measuring the free chlorine content in the disinfectant solution forming in the dilution tank, - a display suitable for displaying the free chlorine content measured by the free chlorine sensor.

[0030] Typically, the system according to the present invention further comprises regulating means for regulating the pH of the disinfectant solution being formed in the dilution tank.

[0031] Advantageously, the system according to the present invention further comprises a control unit operatively connected to the device for measuring the free chlorine content, which control unit is adapted to compare the free chlorine content measured by the sensor and a threshold value of the free chlorine content, and to interrupt the electrolysis when the free chlorine content measured by the sensor is equal to or greater than the threshold value of the free chlorine content.

[0032] In particular, the threshold value of free chlorine content is set at a maximum value selected in a range of 5 ppm to 3000 ppm, in particular in a range of 10 ppm to 1500 ppm.

[0033] In practice, the dilution tank has a water inlet which is connected to a water source by a water supply circuit comprising, in the direction of the dilution tank, a solenoid valve and a circulation pump.

[0034] In practice, the dilution tank has a sampling outlet for the disinfectant solution, which sampling outlet is connected to a tapping provided on the water supply circuit between the solenoid valve and the circulation pump so that the sampling line forms, with the pump and the part of the water supply circuit located after this pump, a recirculation loop which is configured to circulate the disinfectant solution from the sampling outlet to the water inlet.

[0035] Preferably, the free chlorine measuring device is placed on the recirculation loop, in particular on the sampling line, so as to allow continuous measurements to be taken on the disinfectant solution.

[0036] The aqueous solution to be electrolyzed may have a pH of 3 to 8, preferably a pH of 6 to 8.

[0037] According to another aspect, the present invention relates to a method for producing a disinfectant solution containing hypochlorous acid. This method is remarkable in that it comprises: a) a step of providing a system according to the present invention; b) a step of filling the dilution tank of said system with water, and in which the filling of the dilution tank with water causes the filling of the electrolysis chamber of the at least one electrolyzer of said system via the conduit putting said electrolysis chamber and said dilution tank into fluid communication, in order to prepare an aqueous solution containing chloride ions by dissolving a portion of the alkali chloride stored in said electrolysis chamber;c) a step of applying an electric current to the electrodes of the at least one set of electrodes of said at least one electrolyzer to electrolyze the aqueous solution containing chloride ions in said enclosure in order to produce hypochlorous acid, and in which at least a portion of the hypochlorous acid migrates from said enclosure to said dilution tank via said conduit, the at least a portion of hypochlorous acid having migrated diluting in the water present in said dilution tank in order to form the disinfectant solution; d) a step of measuring the free chlorine content of the disinfectant solution being formed in said dilution tank; e) a step of interrupting the electrolysis when the free chlorine content measured in step d) reaches a desired free chlorine content value for the disinfectant solution;f) optionally, a step of measuring the free chlorine content by a sensor capable of measuring the free chlorine content of the disinfectant solution forming in said dilution tank; g) optionally, the interruption of the electrolysis provided for in step e) is handled by a control unit adapted to compare the free chlorine content measured by the sensor in step f) and a threshold value of the free chlorine content and to interrupt the electrolysis when the free chlorine content measured by the sensor is equal to or greater than the threshold value of the free chlorine content; h) optionally, a step of measuring at least one intrinsic parameter of the disinfectant solution being formed in the dilution tank, which intrinsic parameter is chosen from the list of parameters comprising pH, temperature, conductivity, and hardness; i) optionally, a step of regulating the pH of the disinfectant solution being formed in the dilution tank.

[0038] In particular embodiments, the current voltage applied to the electrodes, in step c) of the method, is between 1 and 15 volts, preferably between 2 and 10 volts.

[0039] Advantageously, the disinfectant solution containing hypochlorous acid has a pH of about 5.1 to about 6.9, preferably a pH of about 6.5. Preferably, in optional step g) of the method, the threshold value of the free chlorine content is set to a maximum value selected from a range of 5 ppm to 3000 ppm, in particular from a range of 10 ppm to 1500 ppm. Brief description of the figures.

[0040] Other advantages and characteristics of the invention will appear more clearly on reading the description of the preferred embodiment which follows, with reference to the appended drawings, produced as indicative and non-limiting examples and in which: [Fig. 1] is an illustration of dissociation curves of hypochlorous acid in water as a function of pH; [Fig. 2] is a schematic representation of a system for producing a disinfectant solution according to the invention equipped with a dilution tank and an electrolyser; [Fig. 3] is a schematic representation of another production system of a disinfectant solution according to the invention equipped with a dilution tank and two electrolysers; [Fig. 4] is a photographic representation of a system for producing a disinfectant solution according to the invention equipped with a dilution tank and three electrolysers; [Fig. 5] is a perspective view of an exemplary electrolyzer suitable for the present invention; [Fig. 6] is a perspective view of an example of a hollow tube that can serve as a support element for a set of electrodes of the system according to the invention; [Fig. 7] is a perspective view of an example of an electrode set suitable for the present invention; [Fig. 8] is a schematic representation of the system of Figure 2 further equipped with a device for measuring the free chlorine content; [Fig. 9] is a schematic representation of the system of Fig. 8 further equipped with a control unit; [Fig. 10] is a schematic representation of the system of Figure 9 according to a first variant, the system being further equipped with a recirculation loop and the dilution tank of which is fitted with level detectors; [Fig. 11] is a schematic representation of the system of Figure 9 according to another embodiment variant, the system furthermore being equipped with another form of recirculation loop and the dilution tank of which is provided with level detectors; [Fig. 12] is a schematic representation of an example of a dilution tank of the system of the invention according to an alternative embodiment, in which the dilution tank is provided with a tubular gauge. Description of the embodiments.

[0041] This description is given without limitation, each characteristic disclosed only in one embodiment being generalizable to other embodiments. Similarly, one or more characteristics disclosed only in one embodiment may be combined with one or more other characteristics disclosed only in another embodiment.

[0042] This description is given without limitation, each characteristic exposed only in one embodiment being able to be generalized to the other embodiments. Similarly, one or more characteristics exposed only in one embodiment can be combined with one or more other characteristics exposed only in another embodiment. It should be noted from now on that the appended figures are very simplified, the elements represented therein are therefore not necessarily to scale with respect to each other or from one figure to another. Each reference retains the same meaning from one figure to another.

[0043] The present invention primarily relates to a system for producing a hypochlorous acid-based disinfectant solution, preferably a disinfectant solution containing hypochlorous acid with a free chlorine content greater than 5 ppm. This system can be used by users to produce the disinfectant solution on a small scale, on-site or on demand, or on an industrial scale.

[0044] By "ppm" we mean parts per million. It should be noted that in the case of an aqueous solution, a concentration of 1 ppm can be expressed as follows: 1 ppm = 1 mg / kg = 1 mg / L.

[0045] The system which is the subject of the invention comprises: - at least one electrolyser 100, and - a 300 dilution tank dedicated to the preparation of the disinfectant solution.

[0046] By "at least one electrolyser" is meant one electrolyser (see figure 2), two electrolysers (see figure 3), three electrolysers (see figure 4) or more than three electrolysers. Also, for the sake of simplification, only the case of the system with a single electrolyser, shown in figure 2, will be addressed in the remainder of the description, but the system and the method according to the present invention operates in a similar manner with two, three or more than three electrolysers, and, advantageously, with high performance in the production of hypochlorous acid and disinfectant solutions containing it.

[0047] Furthermore, the electrolyser 100 implemented comprises an electrolysis enclosure 110 equipped with at least one set of electrodes 120.

[0048] By "at least one set of electrodes" is meant one set of electrodes (see for example Figure 2), two or more sets of electrodes (see Figure 5). Here too, for the sake of simplification, only the case of the electrolyser with a single set of electrodes, shown in Figure 2, will be addressed in the remainder of the description, but the system and the method according to the present invention operates in a similar manner with two or more sets of electrodes, and, advantageously, with high performance in the production of hypochlorous acid and disinfectant solutions containing it.

[0049] On the other hand, as will be described later, the dilution tank 300 of the system is provided with at least one bottom outlet 303. In principle, each at least one bottom outlet 303 is intended to be used with an electrolyzer 100. The dilution tank 300 may be provided with two, three or more bottom outlets 303 but of which only one bottom outlet 303 is connected to an electrolyzer 100. For example, in relation to FIG. 2, only one electrolyzer 100 equips the system according to the invention, and the dilution tank 300 is shown with only one bottom outlet 303. However, the dilution tank 300 may be a tank with several bottom outlets in which the unused bottom outlets can be closed by a suitable closing means (e.g. cap, tap, closing valve, etc.).

[0050] Electrolyzer 100

[0051] The set or sets of electrodes 120 of the at least one electrolyser 100 are each intended to be supplied with electricity by an energy source 101 producing an electric current. This may be a direct and / or pulsed current.

[0052] Referring to Figure 2, the electrolyzer 100 comprises an electrolysis chamber 110 storing alkali chloride in solid form, and generally having an upper opening 111, which can be sealed by a removable cover 130.

[0053] The alkali chloride stored in solid form in the electrolysis chamber 110 is intended to be mixed with water in this chamber 110 in order to produce the aqueous solution containing chloride ions whose electrolysis produces hypochlorous acid.

[0054] According to the present invention, the term "alkali chloride" means sodium chloride, potassium chloride and their mixture. For the sake of simplification, only the case of sodium chloride will be addressed in the remainder of the description, but the system and method according to the present invention apply to all types of alkali chloride.

[0055] By "solid form" is meant according to the present invention any solid form having a weight of about 5 g to 30 g. Preferably, the solid form of alkali chloride such as sodium chloride is chosen from pellets, tablets, and lozenges. The advantages of using alkali chloride in solid form will be discussed later.

[0056] The enclosure 110 may be made of any suitable material that is electrically insulating and resistant to corrosion by the aqueous solution containing the alkali chloride such as sodium chloride as well as by the products generated during electrolysis. Preferably, the enclosure 110 is made of glass or rigid plastic, preferably transparent, for example, polyvinyl chloride (PVC), glass fiber reinforced polypropylene (GRP), or Acrylonitrile-Butadiene-Styrene (ABS) or polycarbonate (PC). It is clear, however, that this list is not exhaustive. The use of a transparent material, glass or plastic, allows for visual inspection of the internal components of the cell 110 and observation of the electrolysis during normal operations.

[0057] In practice, the enclosure 110 has the shape of a cylinder with a circular section which extends in the vertical direction. Its height varies for example from 15 cm to 150 cm or more than 150 cm, and its diameter varies for example from 10 cm to 80 cm, or more than 80 cm. The shapes and dimensions described for the enclosure 110 are given only by way of example, because the latter can have any other shape (e.g. parallelepiped or cylinder with an oval section, or other shapes) and appropriate dimensions, best suited to the use for which the enclosure 110 and the system according to the invention are intended. Furthermore, the enclosure 110 can have any shape generated by a straight line which moves parallel to an axis, resting on two fixed planes. Thus the circular section of a cylindrical enclosure can be truncated to present a flat part 112 in almost its entire height as illustrated in figure 5.

[0058] As shown in Figures 2 and 8 to 12, the electrolysis chamber 110 of the system according to the invention is provided with a set of electrodes 120, which is intended to be connected to the energy source 101 producing an electric current. We can recall here that the invention is not limited to this embodiment and that two, three or even more than three sets of electrodes 120 can equip the electrolysis chamber 110. The number of sets of electrodes 120 to be used can be chosen according to the desired overall performance (e.g. production time of the disinfectant solution containing hypochlorous acid). Indeed, the Applicant has been able to observe that with a system according to the invention comprising a single electrolysis chamber 110, the more the number of sets of electrodes increases, the more the production time of the disinfectant solution having a given free chlorine content is reduced.This is highlighted in [Table 1] of the examples and which shows the effect of the number of electrode sets 120 per electrolyzer 100 on the production time of the disinfectant solution according to the present invention.

[0059] The set or sets of electrodes 120 each comprise at least one anode and one cathode (not shown). We recall here that, according to definitions well known to those skilled in the art, the following must be understood: by "anode" a positive electrode, which will be the site of the oxidation reaction of equation No. 4 (2CI'(aq) Cl2(g) + 2e' ) mentioned above, and by "cathode" a negative electrode, which will be the site of the reduction reaction mentioned above.

[0060] The electrodes of the (at least one) set of electrodes 120 may be made of titanium, titanium coated with a catalytic coating containing metal oxides, such as titanium oxide, ruthenium oxide, iridium oxide and tin oxide; titanium alloy; hastelloy® alloy (nickel-chromium-molybdenum alloy) or any other corrosion-resistant metal or alloy. For example, such a catalytic coating may consist of 45 to 55% titanium oxides, 25 to 30% ruthenium oxide and 20 to 20% of iridium. The electrodes may have a shape of the flat plate type or other suitable shapes best suited to the use for which the (at least) one set of electrodes 120 is intended within the scope of the present invention. Preferably, the electrodes of the (at least) one set of electrodes 120 are in the form of flat plates made of a sufficient thickness (e.g. 1 mm to 4 mm) to be rigid. These flat plates may have a width ranging for example from 25 mm to 100 mm and a sufficient length to be able to insert the (at least) one set of electrodes 120 in the diametrical direction into the enclosure 110 and so that the electrodes of the at least one set of electrodes 120 are at least partially arranged inside the enclosure 110. By way of example for an enclosure with a diameter of 25 cm, the flat plates may have a width of less than 25 cm, for example a length of between 15 cm and 24 cm.In particular, the inter-electrode space is between 0.1 cm and 1.2 cm, preferably between 0.1 cm and 0.5 cm. It should be noted that the closer the electrodes are to each other, the greater the contact / exchange surface area per unit volume and therefore the lower the voltage required. Indeed, as the distance increases, the energy requirement to pass the electric current (carried by the ions) through the aqueous solution containing chloride ions increases. Increasing the distance increases the electrical resistance and therefore, at the same current intensity, the voltage must be increased (Ohm's law).

[0061] In particular embodiments of the invention, not shown, the electrodes of the (at least) one set of electrodes 120 are two in number, including an anode and a cathode, which anode and cathode are in the form of plane plates parallel to each other, and are quite spaced apart from each other, for example 0.1 cm and 1.2 cm, preferably between 0.1 cm and 0.5 cm.

[0062] In other particular embodiments of the invention, not shown, a set of electrodes 120 may comprise two or more anodes and two or more cathodes, which anodes and cathodes are in the form of flat plates parallel to each other, and are alternated in the set. of electrodes 120 and sufficiently spaced from each other, for example 0.1 cm and 1.2 cm, preferably between 0.1 cm and 0.5 cm.

[0063] Preferably, the (at least) one set of electrodes 120 further comprises one or more bipolar electrodes arranged between an anode and a cathode of the (at least) one set of electrodes 120.

[0064] The term "bipolar electrode" is understood to mean, according to the present invention, an electrode located at an intermediate potential between an electrode at a higher potential and another electrode at a lower potential, so that said electrode acts simultaneously as an anode on the part opposite the electrode at the lower potential and as a cathode on the part opposite the other. In the case of flat electrodes, anodic type reactions occur on one face and cathodic type reactions on the other face.

[0065] The bipolar electrode(s) may be made of any corrosion-resistant metal or alloy as for the other electrodes of the at least one set of electrodes 120. Furthermore, the bipolar electrode(s) may also have a shape substantially similar or identical to that of the anode and the cathode of the (at least one) set of electrodes 120. Preferably, the anode, the cathode and the bipolar electrode(s) are all in the form of flat, parallel plates regularly spaced from one another, for example from 0.1 cm to 1 cm. The number of bipolar electrodes per set of electrodes 120 may for example range from 1 to 20, in particular from 2 to 18, for example may be equal to 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17.

[0066] It should be remembered that, per set of electrodes 120, the number of anode(s) may be equal to one or more and the number of cathode(s) may be equal to one or more.

[0067] Bipolar electrodes are well known in the art (JP2004237165A, EP0065889A1, WO2012172118A1).

[0068] Preferably, the at least one set of electrodes is of the non-divided type (non

[0069] In particular embodiments, not shown, the electrolyser 100 or the system according to the invention may also comprise at least one switch or an electrical control circuit usable for reversing periodically, for example every 90 min with a pause time of 5 min, the polarities of the electrodes of the at least one set of electrodes, so that the electric current flows, between the electrodes, in one direction, then in the opposite direction (bipolar operation). The purpose of reversing the polarity of the electrodes is to eliminate or prevent a build-up of deposits (e.g. calcium deposit) on the surfaces of the electrodes during operation. It results in improved operation of the electrodes and allows their service life to be extended. When reversing the polarities, a pause time after depolarization and repolarization of the electrodes of 5 min is optimal, this makes it possible to avoid the formation of short circuits between the electrodes of the at least one set of electrodes 120. These short circuits can gradually deteriorate these electrodes. The reversal of the polarities of the electrodes and the pause time can be controlled for the control unit 600 which will be described in more detail later.

[0070] Advantageously, the (at least one) set of electrodes 120 is configured or adapted to be inserted, in a removable and sealed manner, into the electrolysis enclosure 110 through a respective opening 114 provided for this purpose in a wall of the electrolysis enclosure 110, and so that, in use, the electrodes of said (at least one) set of electrodes 120 are at least partly immersed in the aqueous saline solution to be electrolyzed. The holding in position of the set(s) of electrodes 120 in the wall of the enclosure 110 can be achieved by any means suitable to a person skilled in the art, in particular by insertion with bayonet fitting or by screwing onto the wall through which the (at least one) set of electrodes 120 is inserted. The opening 114 of the wall 112 has for example a diameter of approximately 90 mm.

[0071] In particular embodiments (not shown), the (at least one) set of electrodes 120 is in the form of or is arranged in a cylindrical or parallelepipedal housing, insertable into the electrolysis enclosure 110 and having appropriate peripheral openings or holes so that, in operation, the electrodes of the (at least one) set of electrodes are in contact with the aqueous solution to be electrolyzed, on the one hand, and the alkali chloride such as sodium chloride, in solid form, cannot become encrusted between the electrodes of the (at least one) set of electrodes (120) and cause short circuits in the electrolyser 100, on the other hand.

[0072] In a particular embodiment, presented in particular in FIG. 5, the electrolysis enclosure 110 is provided with elongated hollow tubes 121, with a horizontal axis, each arranged in the enclosure 110. Each of these hollow tubes 121 serves as a support element for a set of electrodes 120 and is designed to facilitate the insertion of the set of electrodes 120 into the enclosure 110, on the one hand, and the removal of the set of electrodes 120 from the enclosure 110, on the other hand, for example when it is desired to carry out control operations to be carried out on the electrodes and / or replacement of the latter. In practice, the elongated hollow tubes 121 each have peripheral holes provided so that, in use, the electrodes of the (at least) one set of electrodes 120 inserted into the respective hollow tube 121 are in contact with the aqueous saline solution to be electrolyzed.Such peripheral holes are also intended to prevent alkali chloride such as sodium chloride, in solid form, from becoming embedded between the electrodes of the (at least one) set of electrodes (120) and causing short circuits in the electrolyser. The elongated hollow tubes may be made of a material substantially identical or similar to that constituting the enclosure 110. Their peripheral holes may have a diameter of 10 mm or less.

[0073] In Figure 6, an elongated hollow tube 121 is shown, the end of which, which is intended to be fixed in the wall 112 of the enclosure 100, has an external thread 119 provided for screwing a set of electrodes 120 provided with a counter-thread (not shown). Of course, other fixing means or techniques than those described with reference to Figure 6 can be provided to ensure the reversible and sealed fixing of a set of electrodes 120 in an elongated hollow tube 121.

[0074] Concerning the arrangement of the (at least one) set of electrodes 120 in the electrolysis chamber 110, reference may be made to patent application WO2012172118A1 in the name of the applicant.

[0075] Generally speaking, referring to Figures 2, 3, 8 to 12, the enclosure 110 is surmounted by a cover 130. This is configured or adapted to close the upper opening 111 of said enclosure 110, in a sealed manner. This cover 130 is removable so as to allow the loading of the alkali chloride in solid form into the enclosure 110, on the one hand, and to allow easy access to the interior of the enclosure 110, in particular to be able to carry out emptying and / or cleaning operations of the enclosure 110, on the other hand. The cover 130 is made of a material substantially similar or identical to that of the enclosure 110, in particular PVC, ABS or PC.

[0076] The cover 130 can be fixed to the enclosure by screwing. In Figure 5, the upper part of the enclosure 110 has an external thread 113 provided for fixing by screwing the cover 130 provided with a counter-thread (not shown). Of course, other fixing means or techniques than those described with reference to Figure 5 can be provided to ensure the reversible closure of the enclosure 110. As an example of these other means or techniques, mention may be made of those commonly used in the field of opening and closing systems for pressure cookers.

[0077] Furthermore, the cover 130 may be equipped with a suitable sealing gasket (not shown), for example made of elastomer, making it possible to create or reinforce the seal between the enclosure 110 and the cover 130.

[0078] In Figures 2 to 5, and 8 to 12, the cover 130 is provided with a conduit 200 (called a communication conduit). This is intended to allow fluid communication between the inside and the outside of the electrolysis enclosure 110. The communication conduit 200 can be used for filling the electrolysis enclosure 110 with water for dissolving the alkali chloride which is already loaded therein in solid form (via the upper opening 111) in order to form the aqueous solution containing chloride ions to be electrolyzed. The communication conduit 200 also allows the movement of the hydrogen gas, at least a portion of hypochlorous acid and, if applicable, the chlorine gas generated in the enclosure 110 during the electrolysis reaction from this enclosure 110 to the dilution tank 300 dedicated to the preparation of the disinfectant solution as will be described in more detail later.

[0079] This communication conduit 200 is made of a material substantially similar or identical to that of the enclosure 110 or the cover 130, in particular made of PVC, ABS or PC. It preferably has the shape of a cylindrical tube with a circular base. In use, it opens at its lower end into the enclosure 110 through a cover orifice 131 arranged in the removable cover 130. The free upper end of this communication conduit 200 is intended to be connected to the dilution tank 300 as will be described below.

[0080] Such a communication conduit 200 can be made in one piece with the cover 130 or be fixedly attached in a sealed manner, for example by means of a rubber sealing ring (not shown) in this cover 130.

[0081] In particular embodiments of the invention (not shown), the electrolysis chamber may further comprise at its lower part an outlet orifice allowing it to be emptied. This outlet orifice may for example be closed by any suitable sealing means, for example by a plug, a tap or the like.

[0082] An example of an electrolyser which can be used with the system according to the present invention is described in patent application WO2012172118A1 in the name of the Applicant, or is marketed by the latter under the brand name CHLOR'IN (https: / / www.chlor-in.com / concept-chlor-in-p3.php).

[0083] In the attached figures, the conduit 200 is a straight and vertical or substantially straight and vertical conduit, but it is possible to provide an inclined conduit, or a conduit of helical shape, vertical or inclined.

[0084] Dilution tank

[0085] The system according to the present invention further comprises a dilution tank 300 in which the disinfectant solution will be prepared by diluting the hypochlorous acid coming from the at least one electrolyzer in water supplied by the water source S.

[0086] The tank 300 is intended to be placed above the at least one electrolyzer 100. The number of electrolyzers may be 1, 2 or 3 or more as indicated above. As can be seen in Figures 2, 3 and 4, this tank 300 is placed above, respectively, 1, 2 and 3 electrolyzers 100. The number of electrolysers 100 is chosen according to the desired overall performance (e.g. production time of the disinfectant solution containing hypochlorous acid, desired hypochlorous acid content for the disinfectant solution). Indeed, the Applicant has been able to observe that for a dilution tank 300 of a given volume of water, the more electrolysers there are, the more the disinfectant solution is obtained with a given concentration of hypochlorous acid in a shorter time. This is highlighted in [Table 1] of the examples presented above, and which shows the effect of the number of electrolysers 120 on the production time of the disinfectant solution according to the present invention.

[0087] The tank 300 according to the invention has at its upper part a water inlet 302 and at its bottom 305 at least one bottom outlet (or orifice) 303 (one bottom outlet per electrolyser).

[0088] The water inlet 302 is dedicated to the introduction of water into the dilution tank 300. It is intended to be connected to a water supply source “S” such as for example a tap or a municipal water pipe, or other.

[0089] In practice, the water to be added to the 300 dilution tank is tap water, but it is obviously possible to use natural spring water, distilled water, or deionized or filtered water.

[0090] Also, in a particular embodiment (not shown), the system according to the present invention may further comprise a water filter arranged between the water supply source S and the water inlet 302 of the dilution tank 300. The purpose of this water filter is to eliminate, or at least reduce, any organic compounds (or organic pollutants) which may be present and which could interact with chlorine, among other electrolysis products of water saturated with sodium chloride. The water filter may be of any type known to those skilled in the art such as, for example, a particulate filter (cartridge filter, microfiltration membrane, sand); an activated carbon filter; an ultrafiltration membrane; a membrane contactor or a gas filtration membrane.

[0091] The bottom outlet 303 of the dilution tank 300 is configured or adapted to connect to the communication conduit 200 of the electrolyzer 100 in order to allow fluid communication between this dilution tank 300 and the interior of the electrolysis enclosure 110 of this electrolyzer 100.

[0092] The bottom outlet 303 can be connected to the communication conduit 200 of the electrolyser 100, for example, by means of any type of suitable quick and sealed connection known to those skilled in the art (see e.g. US5580099A; US20190063652A1; EP0829671A2, US20180252347A1).

[0093] By "bottom outlet 303" is meant a bottom orifice of the tank 300 or a suitable bottom conduit inserted into said bottom orifice of the tank 300, which bottom conduit can be attached and mounted on the dilution tank 300 so that it can be fixed there permanently, or in a removable manner.

[0094] The dilution tank 300 may have any shape (e.g., parallelepiped or cylindrical with an oval cross-section, or other shapes) and appropriate dimensions, best suited to the use for which the enclosure 110 and the system according to the invention are intended. In practice, the tank 300 has the shape of a parallelepiped with a square or rectangular cross-section. The volume of the dilution tank 300 may range from 1 liter to 500 liters or more. Of course, the invention is not limited to these shapes or dimensions for the dilution tank 300.

[0095] In practice, the dilution tank 300 is made of a material substantially similar or identical to that of the enclosure 110, in particular PVC, ABS or PC. It is preferably protected against ambient light, for example by an auxiliary device for protection against ambient light (not shown). This auxiliary device may take the form of a box or a cabinet whose walls are made of opaque material, for example, but not limited to, wood, opaque plastic (e.g. PVC, HDPE), opaque glass, metal (e.g. stainless steel).

[0096] In particular embodiments of the invention (not shown), the dilution tank 300 may further comprise at its lower part an outlet orifice allowing the distribution of the disinfectant solution or the emptying of the tank 300. This outlet orifice may be closed for example by means of a tap or be connected by connection means (e.g. pipe) to a storage tank capable of receiving the disinfectant solution or to a flexible pipe for distributing the latter.

[0097] In particular embodiments of the invention (not shown), the dilution tank 300 may further comprise means for breaking up the chlorine gas bubbles that may come from the electrolysis chamber 110 of the at least one electrolyzer 100 in order to promote the dissolution of the chlorine gas in the water, said means for breaking up said chlorine gas bubbles being arranged at the bottom of the dilution tank 300 at least opposite the conduit 200 putting said electrolysis chamber and the dilution tank 300 into fluid communication. The means for breaking up the gas bubbles may consist of at least one flat plate having perforations whose diameter is sufficient to reduce the size of the gas bubbles to dimensions promoting the dissolution of the chlorine in the water. Preferably, the perforations of the at least one plate have a diameter of less than 5 mm, preferably less than 1 mm. Preferably, the means for breaking the gas bubbles consist of several flat, perforated plates. These plates are generally superimposed in such a way that the perforations of one plate are offset from the perforations of another plate adjacent to it.

[0098] In a variant, not shown, the means for breaking the gas bubbles consist of a strainer made of stainless metal or plastic (e.g. PVC) and with meshes whose size is less than 5 mm, preferably less than 1 mm.

[0099] Use of the system according to the invention.

[0100] The system according to the present invention can be mounted in the manner described below, which is easily deduced from the preceding explanations in relation in particular to figure 1, and without this description of the mounting or use of the system according to the invention having to be interpreted in a limiting sense.

[0101] Step 1: we start with the electrolysis chamber 110, which is in practice already equipped with (at least) one set of electrodes 120. The electrolysis chamber is charged with the alkali chloride such as sodium chloride in solid form. It can be indicated that the quantity of alkali chloride such as sodium chloride to be charged into the electrolysis chamber must be sufficient to prepare an aqueous solution in which a part of the alkali chloride such as sodium chloride is dissolved, for example a brine or an aqueous solution saturated with this alkali chloride. It is recalled here that in the case of sodium chloride, this has a solubility of approximately 357 g per liter of water at CTC. In a particular example, approximately 25 kg of sodium chloride in the form of pellets of approximately 15 g are loaded into an electrolysis chamber with a capacity of approximately 40 liters. It can also be indicated that sodium chloride in the form of pellets of approximately 15 g is available under the brand name AXAL® PRO, from the company K+S Minerais and Agriculture GmbH, located in Germany. As a variation of the particular example described here, potassium chloride or a mixture of sodium chloride and potassium chloride can be used to prepare the aqueous solution to be electrolyzed.

[0102] Step 2: the electrolysis chamber 110 is then closed with its removable cover 130.

[0103] Step 3: the electrolysis chamber 110 loaded with alkaline chloride such as sodium chloride, and closed by its cover 130, is placed under the dilution tank 300. In relation to the particular example mentioned above, a dilution tank of 260 liters is chosen for at least one electrolysis chamber whose capacity is approximately 40 liters.

[0104] Step 4: The conduit 200 of the electrolyser 100 is connected to the corresponding bottom outlet 303 of the dilution tank 300. The connection can be made by any suitable quick and sealed coupling means known to those skilled in the art, as mentioned above. Now, the dilution tank 300 and the electrolysis enclosure 110 of the electrolyser 100 are in fluid communication with each other.

[0105] Step 5: Connect the dilution tank 300 to the water supply source S, if applicable, via a suitable water filter as mentioned above.

[0106] Step 6: Water is introduced into the dilution tank 300 until the latter and also the electrolysis chamber 110 are filled, the latter being filled with water via the bottom outlet 303 of the dilution tank 300 and the conduit 200 of the electrolysis chamber 110 to which this bottom outlet 303 is connected. Here we can mention the advantage of using alkali chloride, such as sodium chloride, in solid form which is that when filling the electrolysis chamber 110, the alkali chloride salt remains at the bottom of the latter.

[0107] Step 7: Wait a sufficient amount of time to allow the formation of chloride ions in the water, by dissolving at least part of the alkali chloride, such as sodium chloride. In practice, this waiting time is approximately 5 minutes to 1 hour.

[0108] Step 8: Once the complete system is assembled, the at least one electrolyzer is supplied with electricity by the energy source 101 in order to start the electrolysis itself.

[0109] In practice, the electric current supplying the electrodes of the at least one set of electrodes 120 (or electrodes of the at least one electrolyser 100) is a direct current. Alternatively, the electrolysis according to the invention can be carried out with a pulsed current.

[0110] Electrolysis in the electrolysis chamber 110 is generally carried out at a pH of approximately 6-8, under a voltage of between 1V and 15V, preferably between 2 and 10V.

[0111] The direct (and / or pulsed) current used can have a current density of between 0.1 A / dm 2 and 10 A / dm 2 , or even above 10 A / dm 2. Preferably, the electrolysis is carried out with a direct (and / or pulsed) current having a current density of between 0.1 A / dm 2 and 5 A / dm 2 .

[0112] After a period of electrolysis sufficient to obtain a disinfectant solution containing hypochlorous acid with the desired content of free chlorine, the electrolysis is interrupted (we will return to this last point in detail later).

[0113] During electrolysis, at least a portion of the chloride ions present in the aqueous solution contained in the electrolysis chamber is oxidized at the at least one anode of the electrolyzer to generate chlorine (Chfg)) following the reaction of equation 4 mentioned above. The chlorine thus generated reacts instantly with the water present in the aqueous solution to produce hypochlorous acid (HOCI( aq)) and hydrochloric acid (HCI(aq)) following the reversible reaction of equation 2 mentioned above. In parallel with the reaction oxidation of chloride ions, there is a reduction of water, at the level of at least one cathode of the electrolyser, into hydrogen gas (H2(g)) and hydroxide ions (OH ) following the reaction of equation 5 mentioned above. Thus, overall the electrolysis of the aqueous solution containing alkali chloride such as sodium chloride, at a pH of 6 to 8 (pH of tap water), leads to the formation of chlorine products (chlorine gas, hypochlorous acid and / or hypochlorite ions) and hydrogen gas, within the electrolysis enclosure 110. However, the latter is in fluid communication with the dilution tank 300, which is filled with water.

[0114] The hydrogen gas, and where appropriate a portion of the chlorine gas, generated in the electrolysis chamber 110 therefore passes through the conduit 220 of the latter, then the bottom outlet 303 of the dilution tank 300 and then passes through the dilution tank 300 containing the water to be discharged into the atmosphere.

[0115] On the other hand, the water contained in the dilution tank 300 and the aqueous solution contained in the electrolysis chamber 110 together form a system which has an automatic tendency to make the concentrations of the chemical species (In this case: water, hypochlorous acid and / or hypochlorite ions and chloride ions) which compose it homogeneous. This phenomenon of “irreversible” displacement of the chemical species which tends to homogenize the composition of the system corresponds to what is called in physical chemistry chemical “diffusion”.

[0116] Thus, in this case, the hypochlorous acid and / or the hypochlorite ions as well as the chloride ions therefore tend to move (or migrate) from the aqueous solution from the electrolysis chamber 110 to the dilution tank 300 and, conversely, water tends to move (or migrate) from the dilution tank 300 to the electrolysis chamber 110.

[0117] It should be noted that chemical diffusion is a phenomenon which, in principle, occurs very slowly if no agitation accelerates it.

[0118] However, it is to the credit of the author of the present invention to have found, despite this highly unfavourable prejudice, that it is possible to produce a disinfectant solution whose free chlorine content (hypochlorous acid and / or ions hypochlorites) can reach 1000 ppm or even more than 1000 ppm in acceptable times, in industrial practice, for example less than 12 hours, by placing the dilution tank 300 above the electrolysis chamber 110, by connecting them fluidically, and by using the movement of the hydrogen gas bubbles and, where appropriate, chlorine gas, generated in the aqueous solution of the electrolysis chamber 110. Indeed, this movement of gas bubbles generates tiny vortices which promote the displacement or diffusion of at least a portion of the hypochlorous acid molecules and / or hypochlorite ions (or chlorine product) from the concentrated medium which is represented in this case by the aqueous solution contained in the electrolysis chamber 110 towards the less concentrated medium which is represented in this case by the water in the dilution tank 300.

[0119] Furthermore, it is possible to adjust the electrolysis so as to generate the formation of gas bubbles, in particular hydrogen gas, so that these bubbles create turbulence capable of forcing the migration of at least a portion of the hypochlorous acid from the electrolysis chamber 110 to the dilution tank 301. For this, the author of the present invention has shown that increasing the number of electrodes per set of electrodes 120 and / or the number of sets of electrodes per electrolyzer makes it possible to promote the generation of such gas bubbles and to reduce the production time of a disinfectant solution containing hypochlorous acid at a given or desired free chlorine content.

[0120] Furthermore, the author of the present invention has surprisingly and unexpectedly found that the disinfectant solutions obtained using the system according to the present invention may possibly contain alkaline chloride such as sodium chloride, but in very low levels, less than 1 ppm, which is very advantageous in a process or system for producing disinfectant solutions.

[0121] We return here to the notion of "sufficient electrolysis period" mentioned above. In fact, the present invention leaves the choice to the user of the system for producing the disinfectant solution comprising hypochlorous acid to determine for himself the free chlorine content which is best suited to the disinfection operation which he plans to carry out, for example air disinfection, disinfection of hard or soft surfaces, disinfection of medical devices, skin disinfection, disinfection of cuts on the skin, disinfection of plants (e.g. salads, fruits, vegetables, vines, plants), disinfection of animal housing, etc.

[0122] Also, to obtain the disinfectant solution with a given free chlorine content that is suitable for the use he wishes to make of it, the user can monitor, during the production process, the free chlorine content of the water contained in the dilution tank 300. Furthermore, when the value of the free chlorine content corresponds to what he desires, the user can interrupt the electrolysis in the electrolyser(s).

[0123] We refer to "free chlorine" as: hypochlorous acid (HOCI) and hypochlorite ions (OCI).

[0124] To monitor the progress of the production of the disinfectant solution containing hypochlorous acid, the user can take samples of the disinfectant solution being formed in the dilution tank 300 and analyze these samples to determine their free chlorine content. The sampling and analysis of the samples can be carried out on an ad hoc basis or online, preferably online.

[0125] The punctual determination of the free chlorine content of the disinfectant solution can be carried out according to conventional analysis methods known to those skilled in the art: colorimetric assay, acid-base titration, amperometric assay, spectrophotometric analysis (see e.g. WO2013121294A1), Oxidation-Reduction Potential (ORP) assay.

[0126] Preferably, as illustrated in Figures 8 to 12, the system according to the present invention further comprises a measuring device 400 comprising: - a sensor 411 adapted to measure the free chlorine content in the disinfectant solution forming in the dilution tank 300, - a display 412 adapted to display the free chlorine content measured by the sensor 411.

[0127] The threshold value of the free chlorine content corresponds to a maximum value, chosen, that the free chlorine content of the disinfectant solution in formation in the dilution tank 300 must not exceed. It is set by the user, for example, to a value greater than or equal to 5 ppm. It is generally chosen in a range between 5 ppm and 3000 ppm, in particular between 10 ppm and 1500 ppm. It should be remembered that the system according to the present invention could be adjusted, if necessary, for example so as to obtain a concentrated disinfectant solution of hypochlorous acid with a free chlorine content equal to or greater than 3000 ppm, in particular, a free chlorine content equal to or less than 10000 ppm

[0128] The measuring device 400 with its sensor 411 and its display 412 may be of a known and commercially available type. It may be connected to a measuring tapping located below the level of the disinfectant solution present in the dilution tank as illustrated in FIG. 8, or in practice, be placed on a recirculation loop 450, as shown in FIGS. 9 to 12.

[0129] The measuring device 400 allows, thanks to its sensor 411, a continuous measurement of the free chlorine content of the disinfectant solution present in the dilution tank, thus allowing real-time monitoring of the production of this disinfectant solution. The continuous display of the free chlorine content measured by the sensor 411 allows the user to monitor, in real time, the production of the disinfectant solution containing the hypochlorous acid and to decide to interrupt the electrolysis at any time when he considers that the disinfectant solution has a sufficiently high free chlorine content for the use he plans to make of it.

[0130] For the purpose of automating the monitoring of the production of the disinfectant solution, the system according to the present invention may further comprise a control unit, designated by the reference 600 in FIGS. 9 to 12. This control unit 600 is functionally connected to the measuring device 400 and is adapted to compare the free chlorine content measured by the sensor 411 and a threshold value of the free chlorine content and to interrupt the electrolysis when the free chlorine content measured by the sensor 411 is equal to or greater than the threshold value of the free chlorine content.

[0131] The threshold value of the free chlorine content corresponds to a maximum value, chosen, which the free chlorine content of the disinfectant solution being formed in the dilution tank 300 must not exceed. This threshold (or maximum) value can be selected in a range of free chlorine content greater than or equal to 5 ppm, in particular, in a range from 5 ppm to 3000 ppm, for example, a range from 10 ppm to 1500 ppm.

[0132] Furthermore, the disinfectant solution forming in the dilution tank 300 generally has a pH greater than 3 and less than 8, in particular from 4 to 7.5. It is preferably maintained or regulated in a pH range of 5 to 7, preferably at a pH of about 5.1 to about 6.9, in particular at a pH of about 6.5.

[0133] It should be noted that in the various applications (e.g. disinfection of air, plant, animal or human surfaces, medical devices, etc.) for which the disinfectant solution produced by the system according to the present invention is suitable, a pH of 5.1 to 6.9, in particular, a pH of approximately 6.5 can be considered optimal.

[0134] Also, preferably, the system according to the present invention further comprises a pH probe 413 for measuring or determining the pH of the disinfectant solution present in the dilution tank 300. This pH probe may be of a known and commercially available type. It may be connected to a measuring tap located below the level of the disinfectant solution present in the dilution tank 300 as illustrated in FIG. 8, or in practice, be placed on a recirculation loop 450 (shown in FIGS. 9 to 12). Alternatively, not shown, the pH probe may be placed immersed in the dilution tank 300 (e.g., use of a digital pH meter with remote probe available under Ref. 2201 LM from MOINEAU Instruments, France).

[0135] In practice, the pH probe 413 is included in the measuring device 400 comprising sensor 411, which measuring device 400 can further be configured to display, using the display 412, the pH value measured by the pH probe 413 in addition to the value of the free chlorine content measured by the sensor 411.

[0136] The system according to the present invention may further comprise a pH control device (not shown) connected to receive a signal from the pH probe 413 and being adapted to inject a pH correcting agent into the dilution tank in response to the signal from the pH probe 413.

[0137] By "pH correcting agent" is meant any acidic aqueous solution or any basic aqueous solution which does not alter the physicochemical characteristics of hypochlorous acid. Preferably, the pH correcting agent is in the form of an aqueous solution containing an acid, preferably chosen from inorganic acids such as boric acid, hydrochloric acid, phosphoric acid and sulfuric acid and / or organic acids such as acetic acid, citric acid, ascorbic acid and propionic acid.

[0138] Typically, the pH regulating device also includes a metering pump capable of injecting a dose of the pH correcting agent into the disinfectant solution.

[0139] The pH control device (metering pump connected to the pH correcting agent reservoir) may be of a known and commercially available type. Its metering pump may be connected to the dilution tank 300 (embodiment not shown) or be arranged at any point in a recirculation loop, such as the loop 450 shown in Figures 9 to 12.

[0140] In practice, the pH probe 413 measures the pH value of the disinfectant solution present in the dilution tank, continuously or periodically, every 10 minutes for example. If the pH value measured by the probe 413 is higher, respectively lower, than a set value, generally set in a pH range of 5 to 7, preferably, a pH range of approximately 5.1 to approximately 6.9, in particular at a pH of approximately 6.5, the metering pump of the pH regulating device injects a dose of pH correcting agent so as to decrease, respectively increase the pH of the disinfectant solution until a pH equal to the set value is obtained.

[0141] The pH regulation device is generally arranged near the pH probe 413 which can be included in the measuring device 400 as mentioned above.

[0142] The measurement and regulation of the pH of the disinfectant solution can be automated, as for the measurement of the free chlorine content, thanks to the use of the 600 control unit presented previously.

[0143] In practice, as shown in Figures 10 to 12, the water inlet 302 of the dilution tank 300 is connected to the water source S by a water supply circuit 420 comprising, in the direction of the dilution tank 300, a valve, preferably a solenoid valve 440 or 441, and a pump 430.

[0144] With the aim of homogenizing the disinfectant solution in the dilution tank 300 and of carrying out measurements, in particular of pH and the free chlorine content of the disinfectant solution, the system according to the present invention may further comprise an external recirculation loop, designated by the reference 450 in FIG. 10.

[0145] This recirculation loop 450 may be formed by a sampling line for at least a portion of the disinfectant solution, designated by the reference 410 in FIGS. 10 to 11, and a portion of the water supply circuit 420, the sampling line 410 being connected, on one side, to a sampling outlet 307 provided on the dilution tank 300 and, on the other side, to a tapping, designated by the reference 421, located on the water supply circuit 420 between the solenoid valve 440 and the pump 430. The latter is provided for pumping and circulating at least a portion (or fraction) of the disinfectant solution in the circulation loop 450, from the sampling outlet 307 towards the water inlet 302 of the dilution tank 300.

[0146] According to a possible variant, shown in Figure 11, the two-way solenoid valve 440 is replaced by a three-way solenoid valve 441, a first way 441a of which is connected to the water source S, a second way 441b is connected to the inlet of the pump 430 and a third way 441c is connected to the sampling line at 410, the third way 441c replacing the tapping 421 used in the previous embodiment. The closing of the first channel 441 a and the opening of the second and third channels 441 b and 441 c of the solenoid valve 441 makes it possible to form a recirculation loop 450' equivalent to the recirculation loop 450 presented previously.

[0147] In practice, as shown in Figures 10 to 12, the sampling outlet 307 is provided in the lower part, on a wall or on the base, of the dilution tank 300 and the water inlet 302 is provided in the upper part of the dilution tank 300. Of course, it is possible to reverse this arrangement. The sampling outlet 307 is then arranged in the upper part of the dilution tank 300 and the water inlet 302 in the lower part of the dilution tank.

[0148] As mentioned above, the measuring sensors or probes (pH and free chlorine level), and the means for regulating the pH of the disinfectant solution can be arranged at the level of such a recirculation loop 450 or 450'. This allows the user to have real-time information on the parameters of the disinfectant solution and therefore to optimally monitor the production of the latter at the concentration desired by the user.

[0149] Preferably, the solenoid valve 440 or 441 and the pump 430 are controlled by the control unit 600.

[0150] Preferably, the dilution tank 300 is provided with disinfectant solution level sensors in order to optimize the operation of the recirculation loop 450 or 450' and the system of the present invention.

[0151] In particular embodiments, shown in Figures 10 to 11, three level detectors are placed in the dilution tank 300, namely a low level detector Ni, a high level detector N2 and an intermediate level detector N3 located between the low level detectors Ni and high level detectors N2.

[0152] In another embodiment, shown in Figure 12, the dilution tank 300 is equipped with a tubular gauge 310 which is placed on the outer wall (or one of the walls) of the dilution tank 300 while being arranged vertically in parallel thereto. As can be seen in this Figure 12, the tube 310 has a lower end 311 fluidly connected to an opening 306 in the lower part of the dilution tank 300 and an end upper 312 fluidly connected to an opening 308 in the upper part of the dilution tank. Furthermore, a low level detector Ni' is placed at the opening 306 of the dilution tank 300 (or at the lower end 311), a high level detector N2' is placed at the opening 308 of the dilution tank 300 (or at the upper end 312), and an intermediate level detector N3' located between the low level detectors Ni' and high level detectors N2'.

[0153] The various level detectors Ni, N2 and N3 (or Ni', N2', and N3') are intended to be connected to the control unit 600 which can be configured to control, for example: - filling the dilution tank 300 with water in response to a low level signal emanating from the low level detector Ni (or Ni'), - interrupting the filling of the dilution tank 300 with water, and then circulating the disinfectant solution in the circulation loop 450 (or 450') in response to a high level signal emanating from the high level detector N2 (or N2'), or - starting the measuring device 400 to begin measuring the free chlorine content of the contents of the dilution tank 300, in response to an intermediate level signal emanating from the intermediate level detector N3 (or N3').

[0154] In practice, for filling the dilution tank 300 with water, the low level detector Ni (or Ni') detects that the level of water or disinfectant solution in the dilution tank 300 is equal to or lower than a predetermined minimum level, it produces a low level signal that the control unit 600 receives. The latter then commands the solenoid valve 440 (or 441) to open the water supply circuit 420 to allow the dilution tank 300 to be supplied with water. In the particular case of the solenoid valve 441, the control unit 600 will command the latter to open the ports 441a and 441b and to close the port 441c.

[0155] Regarding the interruption of filling and the circulation of the disinfectant solution in the circulation loop, when the high level detector N2 (or N2') detects that the level of water or disinfectant solution in the dilution tank is equal to or greater than a predetermined maximum level, it sends a high level signal to the control unit 600. The latter then commands the solenoid valve 440 to close (or the solenoid valve 441 to close its port 441a and open its ports 441b and 441c) and the pump 430 to start sucking a portion of the disinfectant solution out of the dilution tank 300 so that this portion of disinfectant solution circulates in the recirculation loop 450 (or 450') towards the water inlet 302 of the dilution tank 300.

[0156] The system according to the present invention may comprise forced operation and automatic operation.

[0157] With reference to Figures 10 to 12, the control unit 600 may comprise a user interface 601, of the type comprising buttons, making it possible, for example, to select forced operation or automatic operation, to adjust the threshold values, in particular the pH and the free chlorine content, to manage the production of the disinfectant solution (use of one or more electrolysers and / or sets of electrodes). The user interface 601 may also make it possible to control, via the control unit 600, different elements of the system according to the present invention, for example, - The starting or stopping of the energy source 101 supplying electric current to the set or sets of electrodes 120 of the at least one electrolyser 100, and / or - The starting or stopping of at least one electrolyser 100, and / or - Starting or stopping the measuring device 400, and / or - The opening or closing of the solenoid valve 440, and / or - Starting or stopping pump 430, and / or - Starting or stopping the pH regulation device, and / or - The inversion of the polarity of the electrodes of the set(s) of electrodes 120 and, where applicable, the pause time between each inversion of polarity.

[0158] The user interface 601 can also allow the user to obtain information sequentially on the operating status of the system, on the production of the disinfectant solution containing the hypochlorous acid, and in particular, on the pH value measured by the pH probe 413, on the value of the free chlorine level measured by the sensor 411, or on the operating times of the electrolyser(s) 100 recorded by the control unit 600 over time.

[0159] During forced operation, the control unit 600 only controls the interruption of the electrical power supply to the electrolyser(s) 100 when the desired free chlorine content for the disinfectant solution is reached or exceeded.

[0160] During automatic operation, the control unit 600 manages the production of the disinfectant solution containing hypochlorous acid, for example, by authorizing or prohibiting the supply of electrical current to one or more electrolyzers 100, when there are several, and / or the supply of electrical current to one or more electrodes 120, when there are several per electrolyzer 100.

[0161] The control unit 600 can continuously monitor the production of the disinfectant solution in the dilution tank and control the stopping of the electrolyser(s) 100, when there are several of them, by cutting off the electrical current supply to the corresponding set(s) of electrodes, in the event that the free chlorine content measured by the sensor 411 exceeds the pre-recorded threshold value.

[0162] The control unit 600 can continuously monitor the production of the disinfectant solution in the dilution tank and control the stopping of the electrolyser(s) 100, when there are several of them, by cutting off the electrical current supply to the corresponding set(s) of electrodes, in the case where the pH probe has measured a pH outside the previously recorded pH threshold range and where the control unit 600 has detected an anomaly in the operation of the pH regulating device, for example the latter is no longer capable or available to inject the pH correction agent to bring the pH back into the desired pH range.

[0163] In particular embodiments, not shown, the system according to the present invention may further comprise a system 603 for transmitting information remotely and / or a system for storing all of the information of the system according to the invention: - the percentage of production, - the measured pH value of the disinfectant solution, - the measured value of the free chlorine content of the disinfectant solution, - the values ​​of the thresholds set, in particular for pH and free chlorine content, - the operating time of the system according to the present invention, to determine when to change the at least one set of electrodes 120, - the polarity inversion period of the at least one set of electrodes 120, - the occurrence of each power outage, - automatic or forced operation, - triggering diagnostics.

[0164] This information can be recorded at least three times a day for 30 days in a loop. However, it may be preferable to keep information on the diagnosis of the system according to the invention, the occurrence of power outages.

[0165] The control unit 600 is preferably provided with a screen 602 of the liquid crystal screen 82 type, or Liquid Crystal Display in English, or LCD, communicating information on the operation of the system according to the invention to the user.

[0166] For further information on the control unit 600 (its characteristics and uses) one may usefully refer to patent application WO2012172118A1 in the name of the applicant.

[0167] In summary, the system according to the present invention can operate in manual and / or semi-automatic and / or automatic mode, to monitor the production of disinfectant solutions containing hypochlorous acid at the free chlorine contents desired by the user.

[0168] Also, the present invention also relates to a method for producing the disinfectant solution. This method according to the invention comprises: - a step a) in which a system according to the present invention is provided; - a step b) in which the dilution tank 300 and the electrolysis enclosure 110 are filled with water in accordance with the present invention; - a step c) in which an electric current is applied to the electrodes of the at least one set of electrodes 120 of the at least one electrolyzer 100 for electrolyzing the aqueous solution containing chloride ions in the enclosure 110 in order to produce hypochlorous acid, and in which at least a portion of the hypochlorous acid migrates from said enclosure 110 to said dilution tank 300 via the conduit 200, the at least a portion of hypochlorous acid having migrated diluting in the water present in said dilution tank 300 in order to form the disinfectant solution; - a step d) in which the free chlorine content of the disinfectant solution forming in the dilution tank 300 is measured; - a step e) in which the electrolysis is interrupted when the free chlorine content measured in step d) reaches a desired free chlorine content value for the disinfectant solution.

[0169] The desired free chlorine content value means the free chlorine content value desired or selected by the user and which the user considers to be high enough for the user to use with the disinfectant solution containing hypochlorous acid.

[0170] The method according to the present invention may further comprise a step f) in which the free chlorine content is measured by the sensor 411 capable of measuring the free chlorine content of the disinfectant solution forming in said dilution tank.

[0171] The method according to the present invention may further comprise a step g) in which the interruption of the electrolysis provided for in step e) is taken over by the control unit 600 adapted to compare the free chlorine content measured by the sensor 411 in step f) and a threshold value of the free chlorine content and to interrupt the electrolysis when the free chlorine content measured by the sensor 411 is equal to or greater than the threshold value of the free chlorine content. Preferably, this threshold value of the free chlorine content is set to a maximum value selected in a range of 5 ppm to 3000 ppm, in particular in a range of 10 ppm to 1500 ppm.

[0172] The method according to the present invention may further comprise a step h) in which at least one intrinsic parameter of the disinfectant solution being formed in the dilution tank 300 is measured, which parameter intrinsic can be chosen from the list of parameters including pH, temperature, conductivity, and hardness.

[0173] The method according to the present invention may further comprise a step g) in which the pH of the disinfectant solution forming in the dilution tank 300 is regulated.

[0174] Preferably, in step c) the current voltage applied to the electrodes is between 1 and 15 volts, preferably between 2 and 10 volts.

[0175] Advantageously, the disinfectant solution containing hypochlorous acid has a pH of about 5.1 to about 6.9, preferably a pH of about 6.5. These pH ranges are optimal for the applications for which the disinfectant solutions produced according to the present invention are intended.

[0176] The various elements (dilution tank, electrolyser(s), communication conduit, piping, cabling, measuring means (pH, free chlorine content) and regulation, control unit, etc.) of the system according to the present invention can be arranged in a compact, small-sized assembly, which is transportable and ready to be installed and used for the production of hypochlorous acid-based disinfectant solution.

[0177] In practice, the entire system according to the present invention is carried by a vertical support structure capable of supporting at least the dilution tank 300 and the at least one electrolyser 100 (and its electrolysis enclosure 110) and ensuring the rigidity of the assembly. This vertical support structure may, for example, be of the type comprising a frame delimiting a space dedicated to the production of the disinfectant solution according to the invention and in which are arranged: - a first compartment mounted on the chassis and in which the at least one electrolyser 100, and where appropriate the circulation pump 430, can be arranged; - a second compartment arranged above the first compartment and in which the dilution tank 300 can be placed, this second compartment having in its lower part, at least one lower opening, to be able to place, through this at least one lower opening, the duct of communication 200 respective of at least one electrolyser, - the outer walls of the first compartment PC1 and / or second compartment PC2 serving as support for the other elements of the system according to the present invention such as the electrical power source 101, the water supply pipe, the electrical cable(s), and where appropriate, the control unit 600, the solenoid valve 440 (or 441), and other components / elements considered to fall within the scope of the present invention.

[0178] Of course, the invention is not limited to this form of mounting of the system of the present invention. In particular, it is possible to provide a form of frame comprising two opposite parallel side walls (or two opposite pairs of side uprights), an upper horizontal plate provided to support the tank 300, and a lower horizontal plate (or base or plinth) provided to support the at least one electrolyzer 100 and where appropriate the pump 430, the upper and lower plates being fixedly connected to the opposite side walls (or to the opposite pairs of side uprights) and the upper plate having at least one lower opening, for the placement of the respective communication conduit 200 of the at least one electrolyzer.

[0179] An example of a system according to the present invention assembled as a compact assembly is shown in the photograph of Figure 4.

[0180] Furthermore, one or more features disclosed only in one embodiment may be combined with one or more other features disclosed only in another embodiment. Similarly, one or more features disclosed only in one embodiment may be generalized to other embodiments, even if that or those features are described only in combination with other features: - The electrolysis chamber 110 or its cover 130 may be equipped with a pressure gauge to monitor the pressure in this electrolysis chamber 110, - The dilution tank 300 may be fitted with a cover or a ceiling having an orifice for the evacuation of gas (hydrogen and, where appropriate, chlorine gas), - The electrodes of the at least one set of electrodes 120 may be solid or perforated, - The electrolysis enclosure(s) 100 may be mounted on a base or pedestal, - The support structure provided to support the system according to the present invention may be equipped with rolling means such as casters in order to facilitate the movement of the entire said system. Examples

[0181] Various tests for the production of a disinfectant solution containing hypochlorous acid with a free chlorine content of 250 ppm were carried out with the following operating conditions: - Dilution tank 300 = 260 liters, - Electrolysis chamber = 40 liters, - Set(s) of electrodes = per set of electrodes, 7 flat plates arranged in parallel rows of alternating polarity. The plates are 210 mm long by 55 mm wide, and are made of titanium coated with titanium oxide, ruthenium oxide and iridium oxide, - Room temperature (around 25°C), - The disinfectant solution was maintained at pH = 6.5, - The applied voltage = between 4 and 6 volts, - Current intensity = between 15 and 30 amps.

[0182] [Table 1] Number Number of sets Electrode electrolyzer production time (in hours) Test 1 1 1 7 to 9 Test 2 2 1 5 to 7 Test 3 3 1 3 to 5 Test 4 1 2 5 to 7 Test 5 2 2 3 to 4 Test 6 3 2 2 to 3

[0183] It is clear from this table that for the production of a disinfectant solution containing hypochlorous acid at a given free chlorine content, the more the number of electrolysers and / or sets of electrodes increases, the shorter the production time of said disinfectant solution.

[0184] The invention is not limited to the embodiments described. Furthermore, in the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim. Furthermore, the use of the verb "to comprise", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim. Of course, one or more characteristics disclosed only in one embodiment may be combined with one or more other characteristics disclosed only in another embodiment. Similarly, one or more characteristics disclosed only in one embodiment may be generalized to the other embodiments.

Claims

Claims

1. (System for producing a disinfectant solution containing hypochlorous acid, comprising: - a dilution tank (300) dedicated to the preparation of the disinfectant solution, which tank (300) comprises a water inlet (302) allowing the filling of said tank with water, - at least one electrolyser (100) arranged below the dilution tank (300), and comprising: -- an electrolysis chamber (110) storing alkali chloride in solid form, - at least one set of electrodes (120) comprising at least one anode and at least one cathode arranged in the electrolysis chamber (110), -- a conduit (200) placing the electrolysis chamber (110) and the dilution tank (300) in fluid communication, wherein said conduit (200) is arranged so that filling the dilution tank (300) with water causes the electrolysis chamber (110) to be filled with water, to prepare an aqueous solution containing chloride ions by dissolving a portion of the alkali chloride stored in said chamber (110), and so that when said aqueous solution is electrolyzed in the electrolysis chamber (110) using the set of electrodes (120) to produce hypochlorous acid, at least a portion of the hypochlorous acid can migrate from said chamber (110) to said tank (300), and can dilute in the water present in said tank (300) in order to form the disinfectant solution.

2. System according to claim 1, wherein the electrolysis of the aqueous solution in the electrolysis chamber (110) of the at least one electrolyzer is adjusted to generate the formation of gas bubbles, so that said bubbles create turbulence capable of forcing the migration of at least a portion of the hypochlorous acid from the electrolysis chamber (110) to the dilution tank (301) via the conduit (200).

3. A system for producing a disinfectant solution according to claim 1 or 2, wherein the at least one electrolyzer (100) is one or two or three or more electrolyzers (100).

4. A system for producing a disinfectant solution according to one of claims 1 to 3, wherein the at least one set of electrodes (120) is one or two or more sets of electrodes (120).

5. A system for producing a disinfectant solution according to one of claims 1 to 4, wherein the at least one set of electrodes (120) further comprises a plurality of bipolar electrodes interposed between an anode and a cathode of the at least one set of electrodes (120).

6. A system for producing a disinfectant solution according to claim 5, wherein the at least one anode, the at least one cathode and the plurality of bipolar electrodes of the at least one set of electrodes (120) are all in the form of flat, parallel plates regularly spaced from each other.

7. A system for producing a disinfectant solution according to one of claims 1 to 4, wherein the at least one set of electrodes (120) comprises a plurality of anodes and a plurality of cathodes, which pluralities of anodes and cathodes are in the form of flat plates arranged in parallel rows of alternating polarity.

8. System for producing a disinfectant solution according to one of claims 1 to 7, wherein the electrolysis chamber (110) of the at least one electrolyser (100) has a capacity of at least 10 litres.

9. System for producing a disinfectant solution according to one of claims 1 to 8, in which the dilution tank (300) comprises means for breaking the bubbles of chlorine gas which may come from the electrolysis chamber (110) of the at least one electrolyser (100) in order to promote the dissolution of the chlorine gas in the water, said means for breaking said bubbles of chlorine gas being arranged at the bottom of the dilution tank (300) at least opposite the conduit (200) putting said electrolysis chamber (110) and the dilution tank (300) into fluid communication.

10. A system for producing a disinfectant solution according to claim 9, wherein the means for breaking up the gas bubbles are consisting of at least one flat plate and having perforations whose diameter is sufficient to reduce the size of the gas bubbles to dimensions promoting the dissolution of chlorine in the water.

11. A system for producing a disinfectant solution according to claim 10, wherein the perforations of the at least one plate have a diameter of less than 5 mm, preferably less than 1 mm.

12. System for producing a disinfectant solution according to claim 11 or 12, in which the means for breaking the gas bubbles are constituted by several flat and perforated plates, these plates are superimposed in such a way that the perforations of one plate are offset relative to the perforations of another plate which is adjacent to it.

13. System for producing a disinfectant solution according to one of claims 1 to 12, further comprising a measuring device (400) comprising: - a sensor (411) adapted to measure the free chlorine content in the disinfectant solution forming in the dilution tank (300), - a display (412) adapted to display the free chlorine content measured by the sensor (411).

14. A system for producing a disinfectant solution according to one of claims 1 to 13, further comprising regulating means for regulating the pH of the disinfectant solution being formed in the dilution tank (300).

15. System for producing a disinfectant solution according to one of claims 1 to 14, further comprising a control unit (600) operatively connected to the device (400) for measuring the free chlorine content, which control unit (600) is adapted to compare the free chlorine content measured by the sensor (411) and a threshold value of the free chlorine content and to interrupt the electrolysis when the free chlorine content measured by the sensor (411) is equal to or greater than the threshold value of the free chlorine content.

16. The system of claim 15, wherein the threshold value of the free chlorine content is set to a selected maximum value. in a range of 5 ppm to 3000 ppm, particularly in a range of 10 ppm to 1500 ppm.

17. System for producing a disinfectant solution according to one of claims 1 to 16, in which the water inlet (302) of the dilution tank (300) is connected to a water source (S) by a water supply circuit (420) comprising, in the direction of the dilution tank (300), a solenoid valve (440, 441) and a circulation pump (430).

18. System for producing a disinfectant solution according to claim 17, wherein the dilution tank (300) has a sampling outlet (307) for the disinfectant solution, which sampling outlet (307) is connected to a tapping (421, 441c) provided on the water supply circuit (420) between the solenoid valve (440) and the circulation pump (430) so that the sampling line (410) forms with the pump (430) and the part of the water supply circuit (420) located after the pump (430) a recirculation loop (450, 450') configured to circulate the disinfectant solution from the sampling outlet (307) to the water inlet (302).

19. System for producing a disinfectant solution according to claim 18 in combination with claim 13, wherein the free chlorine measuring device (400) is placed on the recirculation loop (450, 450'), in particular on the sampling line (410), so as to allow continuous measurements to be carried out on the disinfectant solution.

20. A method for producing a disinfectant solution containing hypochlorous acid, comprising: a) a step of providing a system according to one of the preceding claims; b) a step of filling the dilution tank (300) of said system with water, and wherein the filling of the dilution tank (300) with water causes the filling of the electrolysis chamber (110) of the at least one electrolyzer (100) of said system via the conduit (200) placing said electrolysis chamber (110) and said dilution tank (300) in fluid communication, in order to prepare an aqueous solution containing chloride ions by dissolving a portion of the alkali chloride stored in said electrolysis chamber (110); c) a step of applying an electric current to the electrodes of the at least one set of electrodes (120) of said at least one electrolyzer (100) to electrolyze the aqueous solution containing chloride ions in said chamber (110) in order to produce hypochlorous acid, and in which at least a portion of the hypochlorous acid migrates from said chamber (110) to said dilution tank (300) via said conduit (200), the at least a portion of hypochlorous acid having migrated diluting in the water present in said dilution tank (300) in order to form the disinfectant solution; d) a step of measuring the free chlorine content of the disinfectant solution being formed in said dilution tank (300); e) a step of interrupting the electrolysis when the free chlorine content measured in step d) reaches a desired free chlorine content value for the disinfectant solution;f) optionally, a step of measuring the free chlorine content by a sensor (411) capable of measuring the free chlorine content of the disinfectant solution being formed in said dilution tank; g) optionally, the interruption of the electrolysis provided for in step e) is handled by a control unit (600) adapted to compare the free chlorine content measured by the sensor (411) in step f) and a threshold value of the free chlorine content and to interrupt the electrolysis when the free chlorine content measured by the sensor (411) is equal to or greater than the threshold value of the free chlorine content; h) optionally, a step of measuring at least one intrinsic parameter of the disinfectant solution being formed in the dilution tank (300), which intrinsic parameter is chosen from the list of parameters comprising pH, temperature, conductivity, and hardness;i) optionally, a step of regulating the pH of the disinfectant solution forming in the dilution tank (300).;

21. Method according to claim 20, wherein in step c) the voltage applied to the electrodes is between 1 and 15 volts, preferably between 2 and 10 volts.

22. The method of claim 20 or 21, wherein the disinfectant solution containing hypochlorous acid has a pH of about 5.1 to about 6.9, preferably a pH of about 6.

5.

23. Method according to one of claims 19 to 21, wherein in optional step g) the threshold value of the free chlorine content is set to a maximum value selected in a range of 5 ppm to 3000 ppm, in particular in a range of 10 ppm to 1500 ppm.

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