Method and device for disinfecting water and water supply system comprising such device

Abstract

The invention relates to a method for disinfecting water in a water supply system by means of the generation of active chlorine using an electrolysis device comprising an electrolysis cell provided with an electrode on which a voltage difference is applied. The invention also relates to an electrolysis device for disinfecting water in a water supply system by means of the generation of active chlorine. The invention also relates to a water supply system comprising the electrolysis device.

Description

[0001] The invention relates to a method for disinfecting water in a water supply system by generating active chlorine using an electrolysis device, the electrolysis device comprising an electrolysis cell provided with electrodes across which a voltage difference is applied. The invention also relates to an electrolysis device for disinfecting water in a water supply system by generating active chlorine. The invention also relates to a water supply system comprising the electrolysis device.

[0002] Electrolysis is a technique that uses direct current (DC) to drive otherwise non-spontaneous chemical reactions. Electrolysis is known to be used to disinfect water. Typically, sodium chloride (NaCl) is electrochemically converted to produce chlorine. The salt forms Na + and Cl - When the solution is led through an electrolytic cell, while a voltage is applied to the electrodes of the cell, chlorine (Cl2), oxygen and hydrogen ions are formed at the anode, and hydrogen and hydroxyl ions are formed at the cathode.

[0003] Depending on the pH, the chlorine formed at the anode can also appear as hypochlorous acid (HClO) or hypochlorite (ClO - ). Dissolved chlorine, hypochlorous acid and hypochlorite are called "free chlorine" or "free active chlorine" or "active chlorine". When using (normal) tap water with a pH of about 7 to 8 and containing a small concentration of NaCl, sodium hypochlorite will be formed. The amount of free chlorine to be formed will depend on the desired concentration and the amount of water to be treated.

[0004] An example of an electrolysis device is disclosed in EP 1461291 B1 of the present inventors, which discloses Figure 1The electrolysis device shown in the figure comprises an electrolytic cell 6, the electrolytic cell is provided with electrodes 14a and 14b, a voltage difference is applied to the electrodes 14a and 14b, and the device also comprises a generator 1 arranged in a main pipeline 4 for supplying the voltage difference to the electrolytic cell, the generator comprising an impeller 2 driven by water in a water supply system and a direct current (DC) generator 3. The device further includes a supply pipe 5 for the electrolytic cell, which is connected to the water supply system and guides a part of the water flow in the water supply system to the electrolytic cell; a discharge pipe 7 for the electrolytic cell, which is connected to the water supply system downstream of the position where the supply pipe for the electrolytic cell is connected to the water supply system, and the discharge pipe 7 discharges the water treated in the electrolytic cell to the water supply system; a salt metering device 9 containing a compound capable of supplying chloride ions; a supply pipe 8 for the salt metering device, which is connected to the supply pipe 5 for the electrolytic cell and supplies at least a part of the water in the supply pipe 5 for the electrolytic cell to the salt metering device 9, so as to supply chloride ions to the water to be treated in the electrolytic cell 6; and a discharge pipe 10 for the salt metering device 9, which is connected to the supply pipe 5 for the electrolytic cell downstream of the position where the supply pipe 8 for the salt metering device is connected, and the discharge pipe 10 is connected to the supply pipe 5 for the electrolytic cell, and the discharge pipe 10 is connected to the supply pipe 5 for the electrolytic cell downstream of the position where the supply pipe 8 for the salt metering device is connected. a water supply system 10 for guiding water containing chloride ions from a salt metering device 9 to a supply pipe 5 for an electrolytic cell; and a device for regulating the ratio of the water flow in the water supply system, the feed of the electrolytic cell and the feed of the salt metering device, the device comprising a limiting valve and / or a regulating valve (11, 12), the limiting valve and / or the regulating valve (11, 12) being accommodated in the water supply system, between the position where the supply pipe 5 for the electrolytic cell is connected to the water supply system and the position where the discharge pipe 7 for the electrolytic cell is connected to the water supply system, in the supply pipe 5 for the electrolytic cell, in the discharge pipe 7 for the electrolytic cell, in the supply pipe 8 for the salt metering device and / or in the discharge pipe 9 for the salt metering device; and / or the impeller 2 of the generator 1 is accommodated in the water supply system and is located downstream of the position where the supply pipe 5 for the electrolytic cell is connected to the water supply system and upstream of the position where the discharge pipe 7 for the electrolytic cell is connected to the water supply system.

[0005] Although the electrolysis device of EP 1 461 291 B1 functions well, the inventors have discovered that there is still room for improvement, particularly with regard to the regulation of the energy input and the efficiency of the energy use associated therewith. Summary of the invention

[0006] In a first aspect, the present invention relates to a method for disinfecting water in a water supply system by generating active chlorine using an electrolysis device, the electrolysis device comprising an electrolysis cell provided with electrodes, a voltage difference being applied across the electrodes, wherein the method comprises: providing the voltage difference to the electrolysis cell using an alternating current (AC) generator, wherein the AC generator generates alternating current using water flowing through the water supply system, the alternating current having an alternating current frequency proportional to the flow rate of the water in the water supply system; and converting the generated AC into direct current (DC) using a converter so as to generate the DC and a voltage difference across the electrodes, wherein the converter is controlled to supply the voltage difference and the DC required for electrolytic generation of active chlorine based on the AC frequency.

[0007] In a second aspect, the present invention relates to an electrolysis device for disinfecting water in a water supply system by generating active chlorine, comprising: an electrolytic cell provided with electrodes capable of applying a voltage difference across the electrodes; an alternating current (AC) generator configured to generate alternating current using water flowing through the water supply system, the alternating current having an AC frequency proportional to the flow rate of the water in the water supply system; a converter configured to convert the generated AC power into direct current (DC) for applying a voltage difference across the electrodes of the electrolytic cell; and a control device configured to control the converter to supply DC based on the AC frequency for generating the voltage difference required for electrolytic generation of active chlorine.

[0008] In a third aspect, the present invention relates to a water supply system comprising an electrolysis device according to the second aspect.

[0009] The inventors have discovered that the use of an AC generator according to the present invention allows the generation of the electrical energy required for electrolysis, while at the same time the frequency of the AC generated by the generator can be used to control the energy input required to effectively produce active chlorine. In other words, the amount of active chlorine produced in a given time is based on the AC frequency. In this context, a specific AC frequency can be coupled to produce a specific predetermined amount of active chlorine. In other words, a predetermined amount of active chlorine can be produced in a given time based on a predetermined AC frequency. Accordingly, the electrolytic cell can be configured to produce a predetermined amount of active chlorine in a given time based on a predetermined AC frequency (using input from a control device). In this context, the predetermination of the production of a specific amount of chlorine is intended to limit the amount of chlorine required to purify an amount of water of a given initial quality to a desired quality in a given time, which is consistent with the flow rate of water in the water supply system.

[0010] This is because the AC generator is driven by the flow of water in the water supply, for example by using an impeller driven by the water in the water supply, so that the AC frequency is proportional to the flow rate of the water in the water supply. Therefore, the AC frequency can be used as a measure of the amount of water that needs to be disinfected in an electrolytic cell (e.g., a membrane electrolytic cell). The amount of water that passes through the electrolytic cell within a given time frame is in turn proportional to the required amount of chlorine required for disinfection. In addition, the amount of chlorine produced in a given time depends on the voltage difference between the electrodes and the current flowing between the electrodes. In other words, the more chlorine needs to be produced in a given time, the higher the voltage difference between the electrodes and the current flowing between the electrodes should be. In view of this proportional relationship between these parameters, the inventors have recognized that the AC frequency can be used according to the present invention as a measure of the energy input required to control the effective generation 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 effective for energy use, but the present invention also provides a very reliable and effective method for controlling the amount of chlorine to be produced, because providing energy for electrolysis and its regulation are physically associated with each other, because they both require an AC generator as a key component.

[0011] The present invention is very useful in purifying tap water or water of comparable quality to tap water, or in other words water of relatively good quality. In this regard, it is preferred that the water supply system in the context of the present invention is configured to supply tap water or water of comparable quality to tap water. In this context, the amount of salt required in the electrolytic cell and the voltage and current required for treatment at a certain water flow rate and a desired chlorine content can be effectively controlled based on these parameters, making the present invention a simple and effective system for purifying water.

[0012] With further regard to the AC generator, in a preferred embodiment, the AC generator is housed in the water supply system, downstream of where the supply conduit for the electrolytic cell connects to the water supply system and upstream of where the discharge conduit for the electrolytic cell connects to the water supply system, i.e. the electrolytic cell will then be located in a bypass of the main conduit. Due to this positioning of the AC generator, a slight pressure drop will occur across the generator, as a result of which it is possible to generate a flow of water that will travel through the electrolytic cell. Nevertheless, it is possible to house the generator elsewhere in the water supply system. However, measures will then have to be taken, for example by providing a restricting valve or a regulating valve in the main conduit, to ensure sufficient flow through the electrolytic cell.

[0013] Any electrolytic reaction requires the supply of electrical energy, which means that both voltage and current are required. In practice, a slightly larger voltage is required because the enthalpy (heating) of the product leads to a slightly lower efficiency, which is manifested as an overpotential. For the production of active chlorine as in the present invention, a basic voltage difference is required to initiate the electrolytic process. Depending on the electrode material, this can be, for example, about 0.8V. Once this critical voltage level is exceeded, the electrolytic reaction follows Ohm's law and proceeds at a rate primarily determined by the current. Basically, the higher the current, the more molecules react (electrolysis) per unit time, and the more products (active chlorine) are formed. In view of this, it should be understood that the relationship between the required voltage difference and the current on the electrolytic cell is not always linear.

[0014] Therefore, it is preferred to calibrate the electrolysis device so that the converter is controlled to supply DC based on the AC frequency for generating the voltage difference required for electrolytic production of active chlorine, which includes predetermining the correlation between the flow rate and the corresponding generated AC frequency; and predetermining the correlation between the AC frequency and the corresponding direct current and voltage difference required for electrolytic production of active chlorine; and using these correlations to control the converter so that the voltage difference and direct current required for electrolytic production of active chlorine are applied in the electrolysis cell.

[0015] In a given water supply system, the situation is relatively stable. That is, the same equipment, piping system, valves and electrolytic cells are used for a longer time. Therefore, the control of the required voltage and current in the electrolytic cell can be performed in a relatively simple manner by the controller of the preprogrammed device. In view of this, it is preferred in the device of the present invention that the control device is programmed to control the converter using a predetermined correlation between the AC frequency generated by the AC generator and the corresponding DC and / or voltage difference required for electrolytic production of active chlorine, so that the voltage difference required for electrolytic production of active chlorine is applied to the electrode. Since the device and method of the present invention can usually be used for a longer time in the same water supply system, this can be appropriately achieved by preprogramming the controller, using the required parameters (such as AC frequency and required DC current and voltage) and optionally calibrating the controller to a specific AC generator and electrolytic cell by the flow rate of the water supply system. When the controller detects a certain AC frequency, it can respond by causing the converter to generate a certain DC current, which in turn is linked to a certain voltage to be established on the electrode, which can be achieved via the same controller or a separate controller.

[0016] Although the situation in a given water supply system is relatively stable, deviations or undesirable events may occasionally occur. For example, in the case of suboptimal salt concentrations, the affected voltage difference on the electrodes may be much higher than expected based on a predetermined correlation, because in this case the conductivity in the electrolytic cell is too low due to too few salt ions. In addition, defects may occur in the generator, resulting in too low a voltage on the electrodes. In view of such possible undesirable events, the method according to the present invention may include an alarm system. For this purpose, the actual voltage difference on the electrodes can be determined, and the actual voltage difference can be monitored based on a predetermined correlation of the AC frequency with the corresponding DC and voltage difference values ​​to see if it is consistent with the expected voltage difference. Then, an alarm signal can be generated when the actual voltage difference is not consistent with the expected voltage difference based on the predetermined correlation. Such a system can be implemented in a device according to the present invention, which includes: a voltmeter configured to determine the actual voltage difference on the electrodes; and a monitoring device for monitoring whether the actual voltage difference is consistent with the expected voltage difference based on a predetermined correlation between the AC frequency and the corresponding DC and voltage difference values; and an alarm device configured to generate an alarm signal based on an input from the monitoring device when the actual voltage difference is inconsistent with the expected voltage difference. The alarm system can, for example, include an LED indicator configured to generate an alarm signal.

[0017] The electronic circuit is preferably implemented on one or more printed circuit boards (PCBs). For example, the controller and control device may be included on a PCB, optionally with additional components. The use of a PCB allows for a compact design. Depending on specific needs, the device according to the invention may be equipped with suitable circuits, sensors, etc. based on the common knowledge of the electronics field. The PCB may contain equipment for collecting and storing information about water flow, the amount of water processed, current, voltage, salt concentration, conversion, etc., which may be monitored remotely using a wireless connection.

[0018] Any further equipment may be used in order to design the device according to the invention according to the wishes of the user, such as a pipe system, a conduit system, valves, salt storage and / or salt metering devices etc.

[0019] In an exemplary embodiment, the device can be designed to include an AC generator in the main pipeline for supplying a voltage difference to the electrolytic cell, the AC generator including an impeller driven by water in the water supply system. Such a generator is generally referred to as a turbine generator. In a turbine generator, the flowing water pushes a series of blades mounted on a rotor shaft. The force of the water on the blades causes the rotor shaft of the generator to swerve / rotate. The generator then converts the mechanical (power) energy of the rotor into electrical energy.

[0020] According to the present invention, the (AC) generator is configured to use water flowing through a water supply system to generate AC, the AC having an AC frequency proportional to the flow rate of the water in the water supply system. The device also includes a converter and a control device, the converter is configured to convert the generated AC into direct current (DC) so as to apply a voltage to the electrodes of the electrolytic cell, and the control device is configured to control the converter to supply DC based on the AC frequency to generate the voltage difference required for electrolytic production of active chlorine. The device may further include a supply pipe for the electrolytic cell and a discharge pipe for the electrolytic cell, the supply pipe for the electrolytic cell is connected to the water supply system and guides a portion of the water flow in the water supply system to the electrolytic cell, and the discharge pipe for the electrolytic cell is connected to the water supply system downstream of the position where the supply pipe for the electrolytic cell is connected to the water supply system and discharges the water treated in the electrolytic cell to the water supply system. The device may further include: a salt metering device containing a compound capable of supplying chloride ions; a supply pipe for the salt metering device, which is connected to the supply pipe for the electrolytic cell and supplies at least a portion of the water in the supply pipe for the electrolytic cell to the salt metering device to supply chloride ions to the water to be treated in the electrolytic cell; and a discharge pipe for the salt metering device, which is connected to the supply pipe for the electrolytic cell downstream of the position where the supply pipe for the salt metering device is connected and guides water containing chloride ions from the salt metering device to the supply pipe for the electrolytic cell. The apparatus may further comprise a device for regulating the ratio of the water flow in the water supply system, the feed to the electrolytic cell and the feed to the salt metering device, which device may comprise a restricting valve and / or a regulating valve housed in the water supply system between the location where the supply pipe for the electrolytic cell is connected to the water supply system and the location where the discharge pipe for the electrolytic cell is connected to the water supply system, in the supply pipe for the electrolytic cell, in the discharge pipe for the electrolytic cell, in the supply pipe for the salt metering device and / or in the discharge pipe for the salt metering device, and / or an impeller of the generator housed in the water supply system downstream of the location where the supply pipe for the electrolytic cell is connected to the water supply system and upstream of the location where the discharge pipe for the electrolytic cell is connected to the water supply system.

[0021] The present invention is particularly suitable for disinfecting water in water supply systems that transport water that is not heated to a sufficient temperature. A particular risk for such systems is formed by Legionella. Legionella is a bacterium that can cause airway infections, known as Legionella or Legionnaires' disease. Legionella grows in water and stagnant water at temperatures between 20 and 50 degrees Celsius. Heat pump-based heating systems (which have recently gained more interest in view of the ongoing energy transition) operate within these temperature ranges to heat water, but do not usually heat the water above these temperatures. Therefore, heat pump-based heating systems usually do not provide enough heat to prevent Legionella growth. The present invention allows disinfection of water in water supply systems that involve heat pump-based heating without the need for additional external energy input. In this regard, the method according to the present invention is particularly suitable for preventing Legionella in water supply systems where the maximum water temperature is insufficient to prevent Legionella growth, such as water supply systems that include heat pump-based heating systems. In view of this, the present invention also relates to a water supply system comprising an electrolysis device according to the present invention, which preferably includes a heat pump-based heating system. Implementation of the present invention in a water supply system including a heat pump based heating system saves considerable energy and costs when compared to other disinfection methods such as thermal treatment using boilers, buffer tanks with heat enhancers, or exposing the water to UV-C light. DETAILED DESCRIPTION

[0022] The following exemplary embodiments are intended to illustrate the present invention and not to limit the scope of the claims.

[0023] In the attached Figure 2 In FIG. 1 , an electrolysis device according to a preferred embodiment of the present invention is schematically shown. Figure 2 In FIG, an AC generator 101 including an AC dynamo 103, an impeller 102, and a PCB 113 is shown. The impeller 102 is placed in a main pipe 104 to allow flowing water to drive the dynamo 103. A supply pipe 105 for an electrolytic cell 106 branches off from the main pipe 104 upstream of the AC generator 1 and directs a portion of the water to the electrolytic cell 106. The AC dynamo 103 uses water flowing through the main pipe 104 to generate AC, and the AC frequency is proportional to the flow rate of water in the water supply system using the impeller 102. The PCB 113 converts the generated AC into direct current (DC) for applying a voltage to electrodes 116a, b of the electrolytic cell 106 using a converter implemented on the PCB 113. The converter is controlled to supply DC based on the AC frequency for generating the voltage difference required for electrolytic production of active chlorine. The discharge pipe 107 for the electrolytic cell 106 directs the water treated in the electrolytic cell 106 back to the main pipe 104. In FIG. Figure 2In the device, a salt metering device 109 is also provided. The supply pipeline 108 for the salt metering device 109 branches off a portion of the flow through the supply pipeline 105 for the electrolytic cell 106 and guides it to the salt metering device 109, wherein there is a saturated sodium chloride solution and solid sodium chloride, and wherein the salt is absorbed in the water. The discharge pipeline 110 for the salt metering device 109 guides the water-containing salt back to the supply pipeline 105 for the electrolytic cell 106. Numbers 111 and 112 refer to a check valve and a restriction, respectively. When the generator 101 does not work fully, or when no or insufficient salt is supplied to the water, the current of the electrodes 116a, 116b will drop strongly and the voltage will increase. This can be detected via a detector 114, which in turn submits a signal to a PCB 113, which can, for example, activate an alarm light 115 on the system.

[0024] For use with 10cm 2 For an exemplary electrolytic cell 106 with electrodes on the surface of the electrode, the controller in the PCB can be programmed to deliver the current and voltage required to produce 0.3 mg / L of active chlorine using the correlation based on the values ​​shown in the table.

[0025]

Claims

1. A method for disinfecting water in a water supply system by generating active chlorine using an electrolysis device, the electrolysis device comprising an electrolysis cell provided with electrodes across which a voltage difference is applied, wherein: The method comprises: 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 to generate AC power having an AC power frequency that is proportional to a flow rate of water in the water supply; and The generated alternating current is converted into direct current (DC) using a converter to generate direct current and the voltage difference across the electrodes, wherein the converter is controlled to supply the voltage difference and direct current required for electrolytically generating active chlorine based on the AC frequency.

2. The method according to claim 1, wherein: Based on the predetermined AC frequency, a predetermined amount of the active chlorine is generated in a given time.

3. The method according to claim 1 or 2, wherein: Controlling the converter to supply direct current for generating a voltage difference required for electrolytically generating active chlorine based on the frequency of the alternating current comprises: predetermining the correlation between the flow rate and the corresponding generated AC frequency; predetermining the correlation between the AC frequency and the corresponding DC current and voltage difference required for electrolytic production of active chlorine; and These correlations are used to control the converter so that the voltage difference and the direct current required for electrolytic production of active chlorine are applied in the electrolytic cell.

4. The method according to claim 3, further comprising: An actual voltage difference across the electrodes is determined, and the actual voltage difference is monitored for consistency with an expected voltage difference based on a predetermined correlation of the AC frequency with the corresponding direct current and voltage difference values; wherein an alarm signal is generated when the actual voltage difference is inconsistent with the expected voltage difference.

5. A method according to any one of the preceding claims, wherein: The water supply system includes a heating system based on a heat pump.

6. An electrolysis device for disinfecting water in a water supply system by generating active chlorine, comprising: an electrolytic cell provided with electrodes across which a voltage difference can be applied; an alternating current (AC) generator configured to use water flowing through the water supply to generate alternating current having an AC frequency proportional to a flow rate of water in the water supply; a converter configured to convert the generated alternating current into direct current (DC) for applying the voltage difference across the electrodes of the electrolytic cell; as well as A control device is configured to control the converter to supply the DC based on the AC power frequency for generating a voltage difference required for electrolytically generating active chlorine.

7. The electrolysis device according to claim 6, wherein: The electrolytic cell is configured to produce a predetermined amount of active chlorine in a given time based on a predetermined AC frequency.

8. The electrolysis device according to claim 6 or 7, wherein: The control unit is programmed to: The converter is controlled using a predetermined correlation between the frequency of the alternating current generated by the AC generator and the corresponding direct current and voltage difference required for electrolytic production of active chlorine to apply the voltage difference required for electrolytic production of active chlorine to the electrodes.

9. The electrolysis device according to any one of claims 6 to 8, wherein: The converter and the control device are included in a printed circuit board (PCB).

10. The electrolysis device according to any one of claims 6 to 9, wherein: The AC generator includes an impeller driven by water in the water supply.

11. The electrolysis device according to any one of claims 6 to 10, further comprising: a voltmeter configured to determine an actual voltage difference across the electrodes; a monitoring device for monitoring whether the actual voltage difference is consistent with the expected voltage difference based on a predetermined correlation between the frequency of the alternating current and the corresponding direct current and voltage difference value; as well as An alarm device is configured to generate an alarm signal based on an input from the monitoring device when the actual voltage difference is inconsistent with the expected voltage difference.

12. The electrolysis device according to claim 11, wherein: The alarm device includes an LED indicator configured to generate an alarm signal.

13. A water supply system comprising the electrolysis device according to any one of claims 6 to 12.

14. The water supply system of claim 13, comprising a heating system based on a heat pump.

15. The method according to any one of claims 1 to 5, the electrolysis device according to any one of claims 6 to 12 or the water supply system according to claim 13 or 14, wherein: The water supply system is configured to supply tap water or water of comparable quality to tap water.

16. Use of an electrolysis device according to any one of claims 6 to 12 for preventing Legionella in a water supply system in which the maximum water temperature is insufficient to prevent the growth of Legionella.

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