Method and apparatus for disinfecting water, and a water supply system including such an apparatus

Abstract

The present invention relates to a method for disinfecting water in a water supply system by the production of active chlorine using an electrolysis device comprising an electrolytic cell with electrodes across which a potential difference is applied. The present invention also relates to an electrolysis device for disinfecting water in a water supply system by the production of active chlorine. The present invention also relates to a water supply system comprising said electrolysis device.

Description

[Technical Field]

[0001] The present invention relates to a method for disinfecting water in a water supply system by generating active chlorine using an electrolysis device including an electrolysis cell with electrodes across which a potential difference is applied. The present invention also relates to an electrolysis device for disinfecting water in a water supply system by generating active chlorine. The present invention also relates to a water supply system including such an electrolysis device. [Background technology]

[0002] Electrolysis is a technique that uses direct current (DC) to promote chemical reactions that do not normally occur naturally. The use of electrolysis to disinfect water is well known. Typically, sodium chloride (NaCl) is electrochemically converted to produce chlorine. Na + ions and Cl - The salt dissolves in water, forming ions. As the solution is conducted through an electrolytic cell, a voltage is applied between the electrodes of the cell, and chlorine (Cl2), oxygen ions, and hydrogen ions are formed at the anode, and hydrogen and hydroxyl ions are formed at the cathode.

[0003] The chlorine formed at the anode is converted into hypochlorous acid (HClO) or hypochlorite (ClO), depending on the pH. - Dissolved chlorine, hypochlorous acid, and hypochlorite are referred to as "free chlorine," "free active chlorine," or "active chlorine." When using (common) tap water with a pH of about 7-8 and containing small amounts of NaCl, sodium hypochlorite is formed. The amount of free chlorine produced depends on the desired concentration and the amount of water being treated.

[0004] The present inventor's European Patent No. 1461291 discloses an example of an electrolysis apparatus, as shown in Figure 1. The apparatus comprises an electrolysis cell 6 with electrodes 14a, 14b between which a voltage difference is applied, and also comprises a generator 1 in a main pipe 4 for supplying the voltage difference to the electrolysis cell, the generator comprising a blade wheel 2 driven by water in a water supply system, and a direct current (DC) generator 3. The apparatus further includes an electrolytic cell supply pipe 5 connected to the water supply system and directing a portion of the water flow in the water supply system to the electrolytic cell; an electrolytic cell discharge pipe 7 connected to the water supply system downstream of the position where the electrolytic cell supply pipe is connected to the water supply system and discharging water treated in the electrolytic cell into the water supply system; a salt dosing device 9 containing a compound capable of supplying chloride ions; a salt dosing device supply pipe 8 connected to the electrolytic cell supply pipe 5 and supplying at least a portion of the water in the electrolytic cell supply pipe 5 to the salt dosing device 9 for supplying chloride ions to the water to be treated in the electrolytic cell 6; and a salt dosing device connected to the electrolytic cell supply pipe 5 downstream of the position where the salt dosing device supply pipe 8 is connected and directing water containing chloride ions from the salt dosing device 9 to the electrolytic cell supply pipe 5. a discharge pipe 10 for the electrolytic cell 9; and means for regulating the ratio of water flow in the water supply system, the water supply to the electrolytic cell, and the water supply to the salt dosing device, comprising a constriction and / or a regulating valve (11, 12) applied in the water supply system between the point where the electrolytic cell supply pipe 5 is connected to the water supply system and the point where the electrolytic cell discharge pipe 7 is connected to the water supply system, the electrolytic cell supply pipe 5, the electrolytic cell discharge pipe 7, the salt dosing device supply pipe 8, and / or the salt dosing device discharge pipe 9, and / or a blade wheel 2 of a generator 1 applied in the water supply system downstream of the point where the electrolytic cell supply pipe 5 is connected to the water supply system and upstream of the point where the electrolytic cell discharge pipe 7 is connected to the water supply system.

[0005] Although the electrolysis device of EP 1 461 291 performs well, the inventors have found that there is still room for improvement, particularly with regard to the regulation of energy input and the associated efficiency of energy use. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 1461291 Summary of the Invention [Means for solving the problem]

[0007] In a first aspect, the present invention relates to a method of disinfecting water in a water supply system through the production of active chlorine using an electrolysis device including an electrolytic cell with electrodes across which a voltage difference is applied, the method comprising: supplying the voltage difference to the electrolytic cell using an alternating current (AC) generator, wherein the AC generator uses water flowing through the water supply system to generate an AC current having an AC frequency proportional to the flow rate of water in the water supply system; and converting the generated AC to direct current (DC) using a converter to generate the DC current and the voltage difference between the electrodes, wherein the converter is controlled to provide the voltage difference and DC current required for the electrolytic production of active chlorine based on the AC frequency.

[0008] In a second aspect, the present invention provides an electrolysis apparatus for disinfecting water in a water supply system by the production of active chlorine, the apparatus comprising: an electrolytic cell having electrodes across which a voltage difference can be applied; an alternating current (AC) generator configured to use water flowing through the water supply system to generate an alternating current having an AC frequency proportional to the flow rate of water in the water supply system; a converter configured to convert the generated AC current to direct current (DC) for applying the voltage difference between the electrodes of the electrolytic cell; and a controller configured to control the converter to provide DC for generating the voltage difference required for the electrolytic production of active chlorine based on the AC frequency.

[0009] In a third aspect, the present invention relates to a water supply system including an electrolysis device according to the second aspect.

[0010] The inventors have discovered that the AC generator of the present invention can be used to generate the electrical energy required for electrolysis, while simultaneously controlling the energy input required to effectively produce active chlorine using the frequency of the AC generated by the generator. In other words, the amount of active chlorine produced within a given time period is based on the AC frequency. As used herein, a specific AC frequency can be geared to produce a specific, predetermined amount of active chlorine. That is, a predetermined amount of active chlorine can be produced within a given time period based on the predetermined AC frequency. Accordingly, the electrolyzer can be configured (using a control device input) to produce a predetermined amount of active chlorine within a given time period based on the predetermined AC frequency. Here, the purpose of predetermining the specific amount of chlorine produced is to define the amount of chlorine required to purify a volume of water of a given initial quality to a desired quality within a given time period, in accordance with the flow rate of water in the water supply system.

[0011] This is because the AC generator is driven by the water flow in the water supply system, for example, by using a blade wheel driven by the water in the water supply system. As a result, the AC frequency is proportional to the water flow rate in the water supply system. Therefore, the AC frequency can be used as a measure of the amount of water that needs to be disinfected in an electrolytic cell, such as a membrane electrolytic cell. The amount of water passing through the electrolytic cell in a given time frame is accordingly proportional to the amount of chlorine required for disinfection. Furthermore, the amount of chlorine produced in a given time period depends on the voltage difference between the electrodes and the current flowing between the electrodes. In other words, the greater the amount of chlorine that needs to be produced in a given time period, the greater the voltage difference between the electrodes and the current flowing between the electrodes must be. Considering this proportional relationship between these parameters, the inventors believe that the AC frequency can be used in accordance with the present invention as a measure to control the energy input required for effective production of active chlorine, where a given frequency can be attributed to the required voltage difference between the electrodes and the current flowing between the electrodes. This is efficient in terms of energy use. However, in the present invention, since both the energy supply for electrolysis and its regulation require the AC generator as a key component, they are physically linked to each other, and therefore also provide a very reliable and efficient means for controlling the amount of chlorine produced.

[0012] The present invention is very useful for purifying tap water or water of a similar quality to tap water, in other words, relatively good quality water. In this regard, the water supply system in the context of the present invention is preferably configured to supply tap water or water of a similar quality to tap water. Here, the amount of salt required in the electrolytic cell, as well as the voltage and current required for treatment at a certain water flow and desired chlorine content, can be effectively controlled based on these parameters, thereby making the present invention a simple and effective system for water purification.

[0013] Furthermore, with regard to the AC generator, in a preferred embodiment, the AC generator is applied to the water supply system downstream of the point where the supply pipe for the electrolytic cell is connected to the water supply system and upstream of the point where the discharge pipe of the electrolytic cell is connected to the water supply system, i.e., the electrolytic cell is placed in a bypass of the main pipe. Positioning the AC generator in this way creates a slight pressure drop over the generator, which makes it possible to generate a water flow through the electrolytic cell. Nevertheless, the generator can be applied elsewhere in the water supply system. However, in that case, measures must be taken to ensure sufficient flow through the electrolytic cell, for example, by providing a restriction or a regulating valve in the main pipe.

[0014] Any electrolysis reaction requires a supply of electrical energy, meaning both voltage and current are required. In practice, a slightly higher voltage is required because the enthalpy (heating) of the product slightly reduces efficiency and manifests as overvoltage. To produce active chlorine as in the present invention, a basic voltage difference is required to initiate the electrolysis process. Depending on the electrode material, this may be approximately 0.8 V. Above this critical voltage level, the electrolysis reaction follows Ohm's law and proceeds at a rate determined primarily by the current. Essentially, the higher the current, the more molecules react (electrolyze) and the more product (active chlorine) formed per unit time. With this in mind, it is understood that the relationship between the required voltage difference and the current flowing through the electrolytic cell is not necessarily linear.

[0015] Therefore, it is preferable to calibrate the electrolysis device so that controlling the converter to supply DC for generating the voltage difference required for the electrolytic production of active chlorine based on the AC frequency comprises: determining in advance a correlation between the flow rate and each of the generated AC frequencies; determining in advance a correlation between the AC frequency and each of the DC current and voltage difference values required for the electrolytic production of active chlorine; and controlling the converter using these correlations to apply to the electrolyzer the voltage difference and DC current required for the electrolytic production of active chlorine.

[0016] In a given water supply system, the situation is relatively stable; that is, the same equipment, piping, valves, and electrolytic cell are used for a long period of time. Therefore, controlling the required voltage and current in the electrolytic cell can be achieved in a relatively simple manner by preprogramming the device's controller. In this regard, in the device of the present invention, it is preferable to program the controller to control the converter so that the required voltage difference for the electrolytic production of active chlorine is applied between the electrodes using a predetermined correlation between the AC frequency generated by the AC generator and the DC and / or voltage difference values required for the electrolytic production of active chlorine, respectively. Since the device and method of the present invention can generally be used for a longer period of time in the same water supply system, this can be suitably achieved by calibrating the controller to the specific AC generator and electrolytic cell, for example, by preprogramming the controller with the required parameters, such as the AC frequency and the required DC current and voltage, and optionally the flow rate through the water supply system. When the controller detects a specific AC frequency, it can respond by causing the converter to generate a specific DC current, which is correspondingly related to the specific voltage to be established between the electrodes and may be controlled via the same controller or a different controller.

[0017] Despite the relatively stable conditions in a given water supply system, deviations or undesirable events may occur from time to time. For example, if the salt concentration is not optimal, the amount of salt ions may be too low, resulting in a low conductivity in the electrolytic cell, causing the resulting voltage difference between the electrodes to be much higher than predicted based on the predetermined correlation. Also, a generator defect may occur, resulting in a voltage between the electrodes that is too low. In light of the possibility of such undesirable events, the method according to the present invention may include a warning system. For this purpose, the actual voltage difference between the electrodes may be determined, and based on predetermined correlations between the AC frequency and the DC and voltage difference values, the actual voltage difference may be monitored for consistency with the expected voltage difference. If the actual voltage difference does not match the voltage difference predicted based on the predetermined correlation, a warning signal may be generated. Such a system may be implemented in an apparatus according to the present invention by including: a voltmeter configured to determine an actual voltage difference between the electrodes; a monitoring device that monitors whether the actual voltage difference matches an expected voltage difference based on a predetermined correlation between the AC frequency and each of the DC and voltage difference values; and a warning device configured to generate a warning signal based on input from the monitoring device if the actual voltage difference does not match the expected voltage difference. The warning system may include, for example, an LED indicator configured to generate the warning signal.

[0018] The electronic circuits are preferably implemented on one or more printed circuit boards (PCBs). For example, the controller and control device may be included on the PCB, optionally together with additional components. The use of PCBs allows for a compact design. Depending on specific needs, the device according to the invention may be equipped with appropriate circuits, sensors, etc., based on general knowledge in the field of electronics. The PCBs may include means for collecting and storing information regarding water flow, treated water volume, current, voltage, salinity, conversion, etc., and may be remotely monitored using a wireless connection.

[0019] Any additional equipment may be used to tailor the device according to the invention to the user's needs, such as tubing, plumbing, valves, salt storage and / or salt administration equipment.

[0020] In an exemplary embodiment, the device may be designed to include an AC generator in the mains to supply the electrolyzer voltage difference, the generator including a blade wheel driven by the water in the water supply system. Such generators are commonly referred to as turbogenerators. In a turbogenerator, flowing water pushes against a series of blades attached to a rotor shaft. The water force acting on the blades causes the generator's rotor shaft to spin / rotate. The generator then converts the rotor's mechanical (kinetic) energy into electrical energy.

[0021] According to the present invention, an (AC) generator is configured to use water flowing through a water supply system to generate AC having an AC frequency proportional to the water flow rate in the water supply system. The apparatus also includes a converter configured to convert the generated AC into direct current (DC) for applying the voltage between electrodes of an electrolytic cell, and a control device configured to control the converter to supply DC for generating a voltage difference required for electrolytic production of active chlorine based on the AC frequency. The apparatus may also further include an electrolytic cell supply pipe connected to the water supply system and directing a portion of the water flow from the water supply system to the electrolytic cell, and an electrolytic cell discharge pipe connected to the water supply system downstream of where the electrolytic cell supply pipe is connected to the water supply system and discharging water treated in the electrolytic cell into the water supply system. The apparatus may further include a salt dosing device containing a compound capable of supplying chloride ions, a salt dosing device supply pipe connected to the electrolytic cell supply pipe and supplying at least a portion of the water in the electrolytic cell supply pipe to the salt dosing device, which supplies chloride ions to the water to be treated in the electrolytic cell, and a salt dosing device discharge pipe connected to the electrolytic cell supply pipe downstream of the position where the salt dosing device supply pipe is connected and conducting water containing chloride ions from the salt dosing device to the electrolytic cell supply pipe. The apparatus may also include means for regulating the ratio of water flow in the water supply system, the water supply to the electrolytic cell, and the water supply to the salt dosing device, which may comprise a constriction and / or a regulating valve applied in the water supply system between the point where the electrolytic cell supply pipe is connected to the water supply system and the point where the electrolytic cell discharge pipe is connected to the water supply system, the electrolytic cell supply pipe, the electrolytic cell discharge pipe, the salt dosing device supply pipe, and / or the salt dosing device discharge pipe, and / or a generator blade wheel applied in the water supply system downstream of the point where the electrolytic cell supply pipe is connected to the water supply system and upstream of the point where the electrolytic cell discharge pipe is connected to the water supply system.

[0022] The present invention is particularly suitable for disinfecting water in water supply systems that transport water that has not been heated to a sufficient temperature. In such systems, the risk from Legionella bacteria is particularly high. Legionella bacteria are bacteria that can cause a respiratory tract infection known as Legionnaires' disease. Legionella bacteria grow in stagnant water at temperatures between 20 and 50°C. Heat pump heating systems, which have recently attracted increasing interest in light of the ongoing energy transition, operate to heat water within these temperature ranges but generally do not heat water above these temperatures. Therefore, heat pump heating systems generally do not provide sufficient heat to prevent the growth of Legionella bacteria. The present invention enables the disinfection of water in water supply systems with heat pump heating without requiring additional external energy input. In this respect, the method according to the present invention is particularly suitable for preventing Legionella bacteria in water supply systems where the maximum water temperature is not sufficient to prevent the growth of Legionella bacteria, such as water supply systems that include heat pump heating systems. In this respect, the present invention also relates to a water supply system comprising an electrolysis device according to the present invention, preferably including a heat pump heating system. Implementation of the present invention in a water supply system including a heat pump heating system will result in significant energy and cost savings when compared to other disinfection approaches such as heat treatment using a boiler, a buffer tank with a heat booster, or exposing the water to UV-C light. [Brief explanation of the drawings]

[0023] [Figure 1] [Figure 2] DETAILED DESCRIPTION OF THE INVENTION

[0024] The following exemplary embodiments are intended to illustrate the present invention and not to limit the scope of the claims.

[0025] FIG. 2 attached herewith shows a schematic diagram of an electrolysis apparatus according to a preferred embodiment of the present invention. In FIG. 2, an AC generator 101 is shown comprising an AC dynamo 103, a blade wheel 102, and a PCB 113. The blade wheel 102 is disposed within a main pipe 104 so that the flowing water drives the dynamo 103. A supply pipe 105 for an electrolytic cell 106 branches off from the main pipe 104 upstream of the AC generator 101 and directs a portion of the water to the electrolytic cell 106. The AC dynamo 103 uses the water flowing through the main pipe 104 to generate AC using the blade wheel 102, with an AC frequency proportional to the water flow rate in the water supply system. The PCB 113 uses a converter mounted on the PCB 113 to convert the generated AC into direct current (DC) for applying the voltage between electrodes 116a, b of the electrolytic cell 106. The converter is controlled to supply DC based on the AC frequency to generate the voltage difference required for the electrolytic production of active chlorine. The discharge pipe 107 for the electrolytic cell 106 returns the water treated in the electrolytic cell 106 to the main pipe 104. The system of FIG. 2 also includes a salt dosing device 109. A supply pipe 108 for the salt dosing device 109 diverts a portion of the flow through the supply pipe 105 for the electrolytic cell 106 and guides it to the salt dosing device 109, where saturated sodium chloride solution and solid sodium chloride are present, and salt is incorporated into the water. A discharge pipe 110 for the salt dosing device 109 returns the salt-containing water to the supply pipe 105 for the electrolytic cell 106. Numbers 111 and 112 refer to a check valve and a constriction, respectively. If the generator 101 is not functioning properly, or if no or insufficient salt is supplied to the water, the current to the electrodes 116a, b drops significantly and the voltage rises. This can be detected via a detector 114, which then sends a signal to a PCB 113, which can, for example, activate a warning light 115 on the system.

[0026] 10cm 2 For an exemplary electrolyzer 106 using electrodes with a surface of 0.3 mg / L, a correlation based on values such as those shown in the table below can be used to program a controller in the PCB to provide the desired current and voltage to produce 0.3 mg / L of active chlorine.

[0027]

Table 1

Claims

1. A method for sterilizing water in a water supply system by generating activated chlorine using an electrolytic apparatus including an electrolytic cell equipped with electrodes to which a voltage difference is applied, wherein the method is: A means of supplying the voltage difference to the electrolytic cell using an alternating current (AC) generator, wherein the AC generator uses water flowing through the water supply system to generate an alternating current having an alternating frequency proportional to the flow rate of water in the water supply system; and The generated alternating current is converted to a direct current (DC) using a converter, and the voltage difference between the DC current and the electrodes is generated, wherein the converter is controlled to supply the voltage difference and DC current necessary for the electrolytic generation of activated chlorine based on the AC frequency. A method comprising controlling the converter to supply a DC current to generate a voltage difference necessary for the electrolytic generation of activated chlorine based on the AC frequency, The correlation between the flow rate and the generated AC frequency is determined in advance, The correlation between the AC frequency and the DC current and voltage difference values ​​required for the electrolytic generation of activated chlorine is determined in advance, and These correlations are used to control the converter so that the voltage difference and DC current necessary for the electrolytic generation of activated chlorine are applied to the electrolytic cell, A method that includes this.

2. The method according to claim 1, further comprising determining the actual voltage difference between the electrodes and monitoring whether the actual voltage difference matches an expected voltage difference based on a predetermined correlation between the AC frequency, DC current, and voltage difference value, wherein if the actual voltage difference does not match the expected voltage difference, a warning signal is generated.

3. The method according to claim 1, wherein the water supply system includes a heat pump heating system.

4. An electrolytic device for sterilizing water in a water supply system by generating activated chlorine, An electrolytic cell equipped with electrodes to which a voltage difference can be applied during that time, An alternating current (AC) generator configured to generate an alternating current having an AC frequency proportional to the flow rate of water in the water supply system, using water flowing through the water supply system, A converter configured to convert the generated alternating current into a direct current (DC) for applying the voltage difference between the electrodes of the electrolytic cell, A control device configured to control the converter and supply DC to generate the voltage difference necessary for electrolytically generating activated chlorine based on the AC frequency, This includes, where the control device is An electrolytic device programmed to control the converter so that the voltage difference necessary for the electrolytic generation of activated chlorine is applied between the electrodes, using a predetermined correlation between the AC frequency generated by the AC generator and the DC current and voltage difference values, respectively, that are necessary for the electrolytic generation of activated chlorine.

5. The electrolytic apparatus according to claim 4, wherein the converter and the control device are included in a printed circuit board (PCB).

6. The electrolytic apparatus according to claim 4, wherein the AC generator includes a blade wheel driven by water in the water supply system.

7. A voltmeter configured to determine the actual voltage difference between the electrodes, A monitoring device that monitors whether the actual voltage difference matches the expected voltage difference based on a predetermined correlation between the AC frequency, DC current, and voltage difference value, A warning device configured to generate a warning signal based on the input from the monitoring device when the actual voltage difference does not match the expected voltage difference, The electrolytic apparatus according to claim 4, including the following:

8. The electrolytic apparatus according to claim 7, wherein the warning device includes an LED indicator configured to generate a warning signal.

9. A water supply system including an electrolytic device according to any one of claims 4 to 8.

10. The water supply system according to claim 9, comprising a heat pump heating system.

11. The method according to any one of claims 1 to 3, wherein the water supply system is configured to supply tap water.

12. The electrolytic apparatus according to any one of claims 4 to 8, wherein the water supply system is configured to supply tap water.

13. The water supply system according to claim 9, wherein the water supply system is configured to supply tap water.

14. Use of the electrolytic apparatus according to any one of claims 4 to 8 for the prevention of Legionella in a water supply system where the maximum water temperature is insufficient to prevent the growth of Legionella.

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