Improvements to systems for producing hypochlorite

Abstract

A system for producing hypochlorite, comprises an electrolyser with an inlet for receiving a saline solution and an outlet for the electrolysation products which include hydrogen and hypochlorite; a tank for separating hydrogen from hypochlorite, and a conduit for facilitating the flow of hydrogen and hypochlorite from the electrolyser to the tank; wherein the system further comprising a further conduit from the tank to the electrolyser to facilitate the circulation of hypochlorite from the tank to the electrolyser; wherein the system further comprises one or more of the following a) a heat exchanger which receives hypochlorite from the further conduit; whereby the temperature of the hypochlorite is adjusted prior to returning to said electrolyser; b) a pump for driving the circulation of hypochlorite from the tank to the electrolyser; the pump being configured to drawn in a saline solution for causing the circulation of the saline solution in conjunction with the hypochlorite solution to the electrolyser.

Description

[0001]

[0002] IMPROVEMENTS TO SYSTEMS FOR PRODUCING HYPOCHLORITE

[0003] Field of the invention

[0004] The invention relates to improvements to systems for the production of hypochlorite.

[0005] Background and prior art known to the Applicant(s)

[0006] There are various well-known configurations of electrolysers and systems comprising electrolysers in the market place such the electrolysers described in WO2012127219A3.

[0007] The temperature difference between the inlet (feed saline solution) and outlet (hypo at 8,000 ppm chlorine) of artificial brine electrolysers is approx. 20 degrees Celsius. This is undesirable because of the following problems. First, it may appear logical to chill the inlet saline solution down by approx. 20 degrees Celsius. However, this is not desirable because it is too cold for efficient hypochlorite generation. Secondly, it may appear beneficial to chill the outlet hypochlorite down by approx. 20 degrees Celsius. However, this is also undesirable because it is already too late and too hot and will lead to the rapid decomposition of hypochlorite.

[0008] A number of drawbacks arise from the prior art configurations, these are at least the following:

[0009] If the temperature of an inlet saline solution is too low (for example, equal to or lower than 12 degrees Celsius), then the electrolyser generates more oxygen instead of chlorine, thus the efficiency of hypo generation decreases. The cold water also increases the depletion rate of a mixed metal oxide (MMO) coating on the anodes, thus shortening its operational life from approximately 5 years to maybe 3 years.

[0010] If the temperature of the outlet hypochlorite solution is too high (for example, equal or more than 30 degrees Celsius), then the high temperature causes rapid decomposition of the hypochlorite concentration, where it will tend to revert back to a saline solution.

[0011] By way of further illustration of the prior art and in its drawbacks, figure 1 is provided as an example of an existing system.

[0012] Conventional artificial brine hypo generation is known for a significant temperature increase between the inlet (saline solution) and outlet (hypo solution) of the electrolyser. This issue, intrinsic to the process, is unavoidable and results in several drawbacks, for example:

[0013] • Lower Quality Hypo: Produces lower quality hypo for drinking water chlorination because of the potential formation of undesirable chlorites and chlorates;

[0014] • Reduced Efficiency: Results in inefficient hypo generation with higher electric energy and salt consumption;

[0015] • Reduced Operational Lifespan: Reduces the operational lifespan of the MMO coating on the anode;

[0016] • Shortened Shelf Life: Shortened hypo shelf life (storage) due to decomposition. With artificial brine hypo generation, it is essential to produce hypo at around 8,000 ppm C12 to ensure optimal electric energy and salt consumption. Deviations from this concentration result in increased costs due to higher electric energy or salt consumption. For example, to generate 1 kg C12 / h available C12 in the form of hypo solution at 8,000 ppm C12, the flow rate through the electrolyser must be approximately 125 1 / h.

[0017] Attempts in the prior art to address the aforementioned temperature-related drawbacks:

[0018] Despite limited success, the prior art systems sometimes offer the following options to attempt to mitigate the aforementioned temperature-related drawbacks:

[0019] OPTION 1: INLET PRE-CHILLING

[0020] In this case, the inlet feed saline solution is pre-chilled substantially to achieve an outlet temperature preferably not exceeding 25°C. Any temperature above 25°C will steadily increase the rate of hypo decomposition. However, reducing the inlet temperature by approximately 20°C results in inefficient hypo generation and significantly reduces the operational lifespan of the MMO coating on the anode.

[0021] OPTION 2: OUTLET POST-CHILLING

[0022] In this case, the outlet hypo solution is post-chilled from temperatures ranging from 40°C to 55°C down to 25°C. Any temperature above 25°C will steadily increase the rate of hypo decomposition. However, this method is not truly effective, as the high temperature inside the electrolyser already leads to inefficient hypo generation, rapid hypo decomposition, and the formation of undesirable chlorites and chlorates.

[0023] The current invention seeks to address at least some of these drawbacks when considering various improvements over the prior art systems and electrolysers.

[0024] In particular in at least some embodiments, the configuration has been modified to allow the temperature of the process to be controllable in order to improve the efficiency of the hypochlorite generation whilst avoiding or significantly minimising the undesirable decomposition of the hypochlorite concentration.

[0025] Furthermore, the configuration of systems for producing hypochlorite have been modified to simplify the construction of the system whilst providing improvements in the safety of the cleaning process.

[0026] SUMMARY

[0027] In first broad independent aspect, the invention provides a system for producing hypochlorite, comprising an electrolyser with an inlet for receiving a saline solution and an outlet for the electrolysation products which include hydrogen and hypochlorite; a tank for separating hydrogen from hypochlorite, and a conduit for facilitating the flow of hydrogen and hypochlorite from the electrolyser to the tank; wherein the system further comprises a further conduit from the tank to the electrolyser to facilitate the circulation of hypochlorite from the tank to the electrolyser; wherein the system further comprises a heat exchanger which receives hypochlorite from the further conduit; whereby the temperature of the hypochlorite is adjusted prior to returning to the electrolyser.

[0028] This configuration is particularly advantageous when in certain embodiments, the supply o of saline solution originates from an artificial brine supply which may take the form of a brine tank. Furthermore, it facilitates in preferred embodiments not only a single pass but a multi pass for the hypochlorite.

[0029] In a subsidiary aspect in accordance with the first broad independent aspect, the system comprises a pump for driving the circulation of hypochlorite between the tank and the electrolyser. This configuration is particularly advantageous as it allows the pump to drive recirculation. In further embodiments, it may also facilitate the suction of both brine and water without requiring dedicated brine and water dosing pumps.

[0030] In a further subsidiary aspect, a mixer is provided prior to the pump; the mixer being configured to allow the addition to the flow of hypochlorite of one or more of the following: a saline solution, a cleaning solution or fresh water. This configuration further simplifies the configuration as it avoids in certain embodiments the requirements for separate brine or water dosing pumps.

[0031] In a further subsidiary aspect, the heat exchanger comprises titanium plates. This configuration is particularly advantageous to withstand the chlorite environment and at the same time facilitate thermal conduction leading to the requisite temperature control.

[0032] In a further subsidiary aspect, the heat exchanger comprises a primary heat exchanger and a secondary heat exchanger; the secondary heat exchanger comprises an auxiliary source of coolant. This configuration is particularly advantageous as it may employ ambient sea water for the primary cooling source and associate this with additional tailored levels of cooling provided by the auxiliary heat exchanger.

[0033] In a further subsidiary aspect, the secondary heat exchanger incorporates one or more of the following: an electric chiller, an evaporative chiller and an adiabatic chiller.

[0034] In a second broad independent aspect, the system for producing hypochlorite, comprises an electrolyser with an inlet for receiving a saline solution and an outlet for the electrolysation products which include hydrogen and hypochlorite; a tank for separating hydrogen from hypochlorite, and a conduit for facilitating the flow of hydrogen and hypochlorite from the electrolyser to the tank; wherein the system further comprises a further conduit from the tank to the electrolyser to facilitate the circulation of hypochlorite from the tank to the electrolyser; the further conduit comprising a pump for driving the circulation of hypochlorite from the tank to the electrolyser; the pump being configured to draw in a saline solution for causing the circulation of the saline solution in conjunction with the hypochlorite solution to the electrolyser.

[0035] This configuration is particularly advantageous as, in certain embodiments, it avoids the use of dedicated pumps for brine or water dosing. The pump may itself draw the saline feed and fresh water in appropriate proportions dependent upon flow controllers which may be optionally provided on each one of the feed lines which may include: brine (or other saline solution), fresh water, cleaning solution.

[0036] In a subsidiary aspect in accordance with the second broad independent aspect, a mixer is provided prior to the pump; the mixer being configured to allow the addition to the flow of hypochlorite of one or more of the following: a saline solution, a cleaning solution or fresh water.

[0037] In a further subsidiary aspect, the system further comprises a brine tank and a flow line provided between the brine tank and the mixer through which a saline solution is drawn into the hypochlorite flow. This configuration is particularly advantageous to provide efficient mixing of saline solutions with fresh water and / or with recirculating hypochlorite.

[0038] In a further subsidiary aspect, the system further comprises a heat exchanger which receives hypochlorite from the further conduit; whereby the temperature of the hypochlorite is adjusted prior to returning to the electrolyser. The temperature adjustment is particularly beneficial in order to avoid decomposition of the hypochlorite and to facilitate efficient electrolysation. This configuration envisages that the solution being cooled to optimum temperatures in the circulation loop may include a mixture of fresh water, brine, and hypochlorite.

[0039] When considering the prior art drawbacks described in the background section and the various improvements defined above, these drawbacks are completely resolved with one or a combination of the preceding aspects.

[0040] Particular embodiments of the invention provide:

[0041] • Increased Flow Rate: By increasing the conventional flow rate through the electrolyser, for example, by four times, the temperature rise between the inlet and outlet is proportionally reduced. For instance, a temperature rise of 20°C will be reduced by four times to 5 °C. • Titanium Plate Heat Exchanger: By utilizing a titanium plate heat exchanger with an external coolant, the hypo generation temperature within the continuous circulation flow loop can be precisely controlled between 15°C and 25°C.

[0042] Embodiments of the invention address, decomposition issues associated with too high or low temperatures in artificial brine hypo generation. It ensures the highest quality hypo for drinking water applications by eliminating the formation of undesirable by-products such as chlorites and chlorates, offers the most efficient hypo generation, optimizes the operational life of the MMO coating on the anode, and provides the longest possible hypo shelf life.

[0043] BRIEF DESCRIPTION OF THE FIGURES

[0044] Figure 1 shows a prior art or conventional system.

[0045] Figure 2 shows a flow diagram of a system with an electrolyser, a heat exchanger and a hypochlorite tank as parts of the system, and various appropriate connections such as pipes or conduits between various elements of the system.

[0046] DETAILED DESCRIPTION OF THE FIGURES

[0047] Figure 1 shows a conventional electro-chlorination system. This prior art system is equipped with an electrolyser with an inlet and an outlet. The inlet receives a combination of saturated brie and fresh water. The saturated brine is obtained from a known brine tank. Fresh water is obtained either directly from a fresh water source or from a fresh water tank. The volume in the fresh water tank may be maintained by a float valve. The water may be drawn towards the electrolyser by virtue of a fresh water dosing pump. Separately a brine dosing pump may be provided in the saturated brine line. In the prior art, fresh water may be chilled at the point referenced option 1 shown in figure 1 to reduce excessive high outlet temperature. The power received by the electrolyser may be DC power. The typical power source, power transformer and a thyristor controlled full wave DC rectifier are provided to apply the voltage for the electrolysis. The known products are present in the outlet line to the hypo degassing tank. In this line, outlet post-chilling (option 2) may be applied to reduce excessive high outlet temperature. The preferred hypo storage temperature is 25 degrees Celsius in order to prevent rapid hypo decomposition. A typical hydrogen dilution system may be provided with a dilution air feed and a dilution air discharge. A 100% blower fan so called duty fan and a 100% blower fan so called standby fan are provided.

[0048] By contrast, figure 2 provides an embodiment of an electro-chlorination system for efficiently generating sodium hypochlorite (sometimes also referred to as hypo). The main elements of an embodiment of the system comprise an electrolyser 1, a heat exchanger 2 (where label 105 stands for: Titanium plate heat exchanger), a hypo tank 3 and the connections between them. By contrast with the prior art, the system has a circulation path or loop 4 allowing the hypo to be optionally fed back from the hypo tank to the electrolyser and during this circulation from hypo tank to electrolyser to be cooled by the intervention of a heat exchanger. This allows the hypo to be fed back once or even multiple times. In this feedback loop 4, the hypo may be cooled in order to improve the efficiency of the process and overcome the drawback previously discussed in the background section of the invention.

[0049] The electrolyser 1 may be of known configuration and may for example include a number of electrolysers in parallel or in series capable of receiving a saline solution such as sea water and applying a current to cause the production of hypochlorite and hydrogen.

[0050] The electrolyser 1 is connected, in a preferred embodiment, with a main loop 4 of hypo circulation. The electrolyser comprises an inlet for receiving sufficiently pressurized fluid such as a saline solution (eg. sea water or brine); and an outlet allowing the products to exit from the electrolyser. After exiting the electrolyser, the flow of hypo combined with hydrogen flows at a relatively high flow rate such as positions 102 and 104 of the main feed line.

[0051] The flow exiting the electrolyser outlet is being fed through a temperature sensor or transmitter 5. The temperature sensor provides data to the control system. Optionally, at least one valve is placed before sensor 5. During its hypo production mode of use, the flow is being fed to a hypo tank system 3.

[0052] From the hypo tank system, the hypo may either be directly used for various applications or at least part of the hypo is circulated towards the electrolyser via circulation flow loop 4 which is preferably configured to allow flow to continuously circulate. The hypo circulation flow rate may also be relatively high flow. This hypo circulation is generated by a pump 5 which sits between the hypo tank and the electrolyser. The pump may also be preferably part of a processing unit.

[0053] The pump may be used not only to cause the circulation of hypo from the tank to the electrolyser but also to draw in a saline solution. The combination of hypo and saline solution is then submitted to a heat exchanger 2 prior to reaching the electrolyser. In order to control the circulation between the pump and the heat exchanger, optionally, a spring loaded check valve (not shown) may be provided.

[0054] Various temperatures sensors 6, 7, 8 and 9 may be provided in or adjacent to the pipes before the heat exchanger 2 and after the outlet of the heat exchanger 2. Optionally, the heat exchanger may be a plate heat exchanger. In one of the embodiments, the heat exchanger is optionally a titanium plate heat exchanger (label 105 stands for titanium plate heat exchanger). Depending on the temperature of the inlet flow, it can be optionally chilled by an auxiliary or external coolant supply 10 or chiller and be fed through the heat exchanger for further processing in order to achieve a suitable temperature level to increase the efficiency of the process.

[0055] The flow in the circulation feed may be a hypo which circulates with a relatively high flow rate of approximately 3000 1 / h. In preferred embodiments, the flow rate may be at least 2000 1 / h. The flow rate may be measured and controlled as appropriate by flow controllers such flow controller 11 and flowmeters such as flow meter 12, and is further being fed to the inlet of the electrolyser 1, creating a multi pass loop for a hypo circulation within which cooling takes place to enhance and optimise the production of hypochlorite. The sensors and flow meters may feedback signal to a control unit 103. The control unit may vary the rate of pumping of pump 5 and / or the extent of cooling or heating of the heat exchanger dependent on the measurements obtained in particular with respect to one or more of the following: temperature at the inlet and outlet of the electrolyser, the temperatures at the heat exchanger, and the temperature in the hypo tank.

[0056] The use of the combination of the heat exchanger 2, temperature sensors throughout the hypo circulation path, and the electrolyser, allows the system to react to change in temperature levels and prevents the prior art significant reduction in efficiency where the hypochlorite is simply conveyed in a single pass from the electrolyser to a hypo tank.

[0057] These features lead to special advantages such as increasing the operational life of the electrolyser. In certain embodiments, the operational life may be increased by almost twice as the cooling approach and hypo circulation approach tends to prevent increases of the depletion rate of the mixed metal oxide (MMO) coating of the anodes. Another advantage arises from this configuration by preventing the rapid decomposition of the hypo concentration which can be caused by high temperature of the outlet solution.

[0058] The hypo circulation flow may be configured to exit from the heat exchanger at a high flow rate of approximately 30001 / h. In preferred embodiments, the flow rate may be greater than 2000 1 / h. The flow rate may be controlled and measured by flow controller 11 and flowmeter 12 respectively, which may be connected to a central control unit by appropriate wired or wireless lines of communication as represented by the dotted line. Optionally, at least one spring loaded check valve, a valve and a leak detector may be provided before the inlet to the electrolyser. The electrolyser may be connected to direct current (DC) power and a T / R unit 1 - power transformer and thyristor controlled rectifier with constant current regulation. Other configurations of known kinds are also envisaged for the electrolyser.

[0059] In one of the embodiments envisaged, the electrolyser employed may be a so called parallel plate electrolyser (PPL). Anodes are made of titanium Grl with a MMO coating and Cathodes are made of titanium Grl and uncoated. The operational life of an electrolyser may be of 5 years of continuous operation subject to compliance to the operational specifications of the manufacturer. All external material (casing and inlet / outlet) may be of unplasticized polyvinyl chloride (uPVC). All internal "wetted" materials (electrode "cradle" & supports): titanium Grl, uPVC and ethylene propylene diene terpolymer (EPDM) rubber.

[0060] The electrolyser may in fact be a plurality of connected electrolysers.

[0061] Figure 2 also shows an embodiment where saturated brine is generated for input into the system. A fresh water inlet is regulated by a main stop valve 13. The water enters into the fresh water tank 14 via float valve B. The fresh water box is connected with a brine tank 15, which is filled with a dry salt at an appropriate level such as level A. The fresh water mixes with salt to produce brine. The saturated brine is being withdrawn by the suction of the hypo circulation pump. Optionally, depending on the current system needs, fresh water may also be drawn from the fresh water tank by the suction of the hypo circulation pump. The fresh water and saturated brine are being fed by parallel pipes to the next stage for further measuring of the flow and mixing with the hypo circulation. The brine tank 15 may also optionally comprise a waste outlet which may be open or closed dependent upon the configuration of an appropriately provided valve (not shown in the figure).

[0062] The feed of saturated brine, coming from the brine tank, and fresh water, coming either directly from the water supply or from the fresh water box, arrive in parallel towards circulation suction line 4 upstream from circulation pump 5. Each separate fluid line may comprise at least one flow controller (for example a diaphragm valve) and at least one flowmeter. In one embodiment each inlet to the suction circulation line may comprise at least one or more of the following: a stop valve, a flow control valve, a flow meter, and a ball check valve. Optionally, each line may comprise a ball check valve placed before the connection of the various lines. The various lines (LI, L2, L3, L4) may merge prior to the mixer 32 whereby respective flows of saturated water and fresh water, create a saline solution which is then fed to the suction line, where it is mixed with the hypo circulation.

[0063] The mixing of the saline solution and the hypo circulation is caused by the hypo circulation pump 5 which also causes the circulation between the hypo tank and the electrolyser to achieve relatively high flow rate, for example, a flow rate of approximately 3000 1 / h.

[0064] Optionally, valves are located before and after the hypo circulation pump 5.

[0065] Figure 2 also shows an embodiment for controlling the temperature in a circulation line located between a hypo tank and the electrolyser. The system comprises a heat exchanger with temperature sensors and optionally an auxiliary coolant. In use, a flow of saline solution mixed with the hypo circulation passes optionally through a spring loaded check valve. Additionally, valves may be provided on both sides of the inlet and outlet of the heat exchanger.

[0066] The flow may be measured by the temperatures sensors 6, 7, 8 and 9 in the pipes before reaching heat exchanger 2. The heat exchanger 2 may be a plate heat exchanger. In some of the embodiments, the heat exchanger 2 may be a titanium plate heat exchanger having valves and temperature sensors at each extremity. The flow may be fed through the heat exchanger with a high flow rate. Depending on the temperature of the inlet flow, it may be optionally chilled with an auxiliary coolant supply or chiller. The flow rate of the auxiliary coolant may be controlled by a flow controller diagram valve and a flowmeter. Further, the flow may be controlled depended upon the temperature sensed by the sensors to ensure "stable average temperature" for both efficient hypo generation and to prevent its rapid decomposition. The auxiliary coolant, for example, can be one of many known potential sources of:

[0067] • an electric chiller;

[0068] • an evaporative or adiabatic chiller

[0069] • part of the treatment water (e.g. potable water, process water, etc.)

[0070] In preferred embodiments, relevant temperatures may be sensed by temperature sensors and carefully monitored / controlled by a programmable logic controller (PLC).

[0071] As a result of the application of the heat exchanger, the outlet optimises the operational temperature for efficient electrolysation.

[0072] Figure 2 also shows an electrolyser which may be of any known kind with an inlet and an outlet. Appropriate temperature sensors may be provided such as at its outlet where temperature sensor 5 is located. The electrolyser may optionally be equipped with a valve and a leak detector located before the inlet. The electrolyser may be connected to direct current (DC) power and a T / R unit 1 - power transformer and thyristor controlled rectifier with constant current regulation.

[0073] The invention is not limited to a particular kind of electrolyser and may include several electrolysers operating as a group of electrolysers.

[0074] In one embodiment, the type of electrolyser employed for brine electro -chlorination may be a parallel plate electrolyser so called PPL electrolyser. The anodes may be of titanium Grl with a mixed metal oxide (MMO) coating and the cathodes may be of titanium Grl and uncoated. The operational life of an electrolyser may be of 5 years of continuous operation subject to compliance with the operational specifications of the manufacturer.

[0075] At least one valve may optionally be provided after the electrolyser’ s outlet. A valve may optionally be closed to allow flow to be diverted to waste or for sampling, depending on the stage of the process or current needs.

[0076] Optionally, a waste line may comprise at least one valve and at least one spring loaded check valve. These valves may be operated remotely to facilitate the flow to waste outlet. In addition, a further valve may be provided at an appropriate location on the line to a sampling outlet whereby the various valves may be closed other than the valve in the sampling line in order to allow a flow to be directed to a sampling outlet, where the product of the electrolyser may be assessed.

[0077] A ball check valve and a vacuum breaker may optionally be provided in the electrolyser outlet.

[0078] The temperature sensors may be connected to the electronic control system by either a wireless link or wires such as that shown by a dotted line in the figure. The flow of hypo and hydrogen is being fed to the hypo tank dilution system 17.

[0079] The flow rate of hypo combined with hydrogen between the electrolyser and the tank may be relatively high of approximately 3000 1 / h. In preferred, embodiments, the flow may be at least 20001 / h.

[0080] Figure 2 also shows a hypo tank 3, a safety bund and a hydrogen dilution system 17 with their respective connections to the other parts of the system. The tank 3 serves to separate the hydrogen from the hypochlorite. Label 113 stands for “The preferred hypo storage temperature is less than 25 degrees Celsius in order to prevent rapid hypo decomposition”. A number of sensors are envisaged to monitor the respective levels of hypo and hydrogen. Level sensors may be provided in the form of a laser (not shown in the figure). The hypo tank may be of medium density polyethylene (MDPE) having a maximum capacity of 8000 PPM NaOCl,with a total volume of approximately 1000 litres (NaoCl Volume 800 litres). In preferred embodiments, the tank may comprise a dry space or volume of approximately 20% of the total hypo tank volume and the temperature level may be kept at approximately 25 C°. The time of retention may be approximately 1-2 hours.

[0081] The hypo tank 3 and the safety bund 17 may optionally comprise at least following sensors: 39 - LSHH - High Level trip sensor;

[0082] 40- LSH - Hypo generation pause sensor;

[0083] 41- LSL - Hypo generation run sensor;

[0084] 42 - LSLL- Low level Trip senor.

[0085] In one of the embodiments, a sensor may be an acoustic sensor such as an ultra-sonic sensor.

[0086] The hypo tank may optionally comprise a removable screw top (not shown in the figures) which may be employed for re-filing. The screw top may be positioned above the over-flow line and may be secured to the upper extremity of hypo tank 3. In one of the embodiments, the line is an over-flow water trap, for example, a transparent uPVC tube. The line may be connected to a waste line whereby in case of over-flow, a flow to waste may be facilitated.

[0087] Optionally, a leak detector may be placed near the lower extremity of a safety bund. Sensors and leak detectors may preferably be connected to the electronic control system. The connection to the electronic control system may be wireless or with wires as appropriate for certain embodiments.

[0088] The hypo tank comprises an inlet of air to facilitate the dilution with hydrogen. The air is provided from the hydrogen dilution system. The hydrogen dilution system 17 comprises at least one duty blower fan for the safe hydrogen dilution in the hypo tank 3. The fan may comprise at least one primary blower and at least one optional backdraft shutter. The blower fan can optionally operate at a minimum of 165 m3 / h and 20 mmH20column (rated 230 m3 / h max and 250 Pascal max, 400 Vac, 50 Hz, 3).

[0089] Preferably, hydrogen must be diluted 4 times below the lower explosion limit (LEL) of hydrogen which may therefore aim at achieving only 1% or less hydrogen.

[0090] In one mode of use, when the hypo tank level = LSL, the blower fan = RUN and the blower air sensor = HEALTHY, the current (DC) is applied to the electrolyser in a RUN mode of operation.

[0091] In an alternative mode of use, when the hypo tank level = LSH, the current (DC) to the electrolyser may be paused and the blower’s operation may be delayed for example by a run Delay OFF for 15 minutes to ensure 100% continuous hydrogen dilution because of the delayed hydrogen disengagement from the hypo.

[0092] A dilution air sensor may be provided in the hydrogen dilution system 17. The values measured by the sensor may be communicated to the control system in a similar fashion to other sensor output described herein.

[0093] In one embodiment, the sensor may be provided in close proximity to the dilution air inlet of the hypo tank 3.

[0094] An exhaust line is provided in the upper part of the hypo tank to facilitate the exhaust of hydrogen to the hydrogen dilution air exhaust. The exhaust may be to the open air if it is safe to do so. In preferred embodiments, the system dilutes hydrogen in air 100 times.

[0095] The safety tank may comprises at least one outlet line in the lower extremity of the tank. Whilst the primary outlet will be for the generated hypo one or more further outlet lines are envisaged. One of the further outlet lines may be for waste. Another outlet line may facilitate hypo dosing. A further still outlet may be for sampling. A remotely controllable valve may be provided in one or each of the outlet lines and may be open dependent on the particular mode of operation. The tank may also optionally incorporate an inlet line for service water which may be fed from any appropriate external water source.

[0096] The process of the operating of this stage may be as follows. Hypo generation and hypo dosing may be, in a preferred embodiment, two completely independent processes, where:

[0097] (A) Hypo dosing empties the hypo tank (causes the tank level to drop from LSH to LSL), and,

[0098] (B) Hypo generation fills the hypo tank (causes the tank level to rise from LSL to LSH) Therefore, Hypo generation RUN / PAUSE is controlled by the hypo tank level, where:

[0099] LSL — > Hypo Generation = RUN LSH — > Hypo Generation = PAUSE

[0100] In a particular embodiment, hypo generation is controlled in the following sequential steps: PRECONDITION - All operating conditions, sensors and interlocks must be HEALTHY and ready for Hypo Generation

[0101] STEP 1 - If Hypo Tank Level = LSH, then the systems may be configured:

[0102] • T / R Unit = PAUSE

[0103] • Hypo circulation pump = PAUSE

[0104] • Blower Fan = PAUSE (but Delay OFF for 15 minutes)

[0105] The above hypo generation = PAUSE condition will remain indefinitely, until

[0106] (due to hypo dosing) ...

[0107] STEP 2 - Hypo tank level drops to = LSL

[0108] STEP 3 - Blower fan = RUN

[0109] STEP 4 - If blower air flow rate > 165m3 / h

[0110] STEP 5 - Blower air flow switch = HEALTHY

[0111] STEP 6 - Hypo circulation pump = RUN

[0112] STEP 7 - If hypo circulation flow rate > 3,000 1 / h

[0113] STEP 8 - Hypo circulation flow switch = HEALTHY

[0114] STEP 9 - If INLET saline solution flow rate > 625 1 / h

[0115] STEP 10 - INLET saline solution flow switch = HEALTHY

[0116] STEP 11 - T / R unit = RUN STEP 12 - Hypo tank starts to fill with hypo from LSL to LSH

[0117] Notes for the outlined process:

[0118] • The above hypo generation = RUN condition will remain until the hypo level reached LSH again (STEP 1).

[0119] • The entire process repeats from STEP 1 to STEP 12 continuously.

[0120] • The rate of hypo generation can be reduced below 5 kg C12 / h simply by reducing the rate of hypo dosing. This is because the hypo level drop to LSL (STEP 2) will be slower and subsequently delay the above hypo generation = RUN condition

[0121] • The correct INLET saline solution flow rate (feed fresh water + saturated brine) is achieved by the suction of the Hypo Circulation Pump.

[0122] Scaling (the depositing of calcium and magnesium onto the cathodes) is a naturally occurring phenomenon which takes place in all electrolysers irrespective of the manufacturer.

[0123] Acid washing is generally required to dissolve these deposits. If appropriate acid washing is not carried out on time and in the correct manner, then permanent and irreversible damage to the electrolyser can arise. First grade hydrochloric acid (HC1) between 5% ~ 7% concentration is usually recommended to dissolve these unwanted deposits.

[0124] A hydrogen gas sensor (not shown in the figures) may optionally be provided above the hypo tank 3 and can be a roof mounted sensor. The sensor may be connected with a hydrogen gas sensor located above the electrolyser (not shown in the figures) and connected to the electronics control system. Dependent upon the hydrogen levels detected an alarm signal may be sent to a remote control room. The function of the system can be described in the following manner: If hydrogen is sensed at = or > 1% (which is less than 4 times below the LEL of hydrogen), then the hydrogen sensor / transmitter control panel may be configured to action the following:

[0125] 1. The ESD of the ECU control panel & T / R Unit = RUN

[0126] 2. Container Extractor Fan = RUN

[0127] 3. Visible and audible alarms inside the Container = RUN

[0128] 4. An alarm signal to the customer Remote Control Room is enabled Figure 2 also describes an optional hypo dosing system. The hypo dosing system can be additionally provided and positioned after one of the outlets of the hypo tank 3 to enable hypo inflow (Hypo generation) to be slightly more than the hypo outflow (hypo dosing). If not, then generation will start to fall behind hypo dosing which will result in a continuous system trip because of tank level LSLL. Optionally, the system may include a pulsation dampener, PLV, and valve, a flow controller (diaphragm valve) and a flowmeter positioned adherently on the line and ending with an outlet to hypo dosing.

[0129] The described system is connected to the electricity control system, comprising a control panel. Communications with remote control room via known methods, for example, Profinet communication protocol.

[0130] The system can additionally comprise a safety shower with eye wash, connected to the main stop valve and the source of a fresh water, and having outlet to the waste. A valve may be positioned before the shower.

[0131] Other aspects of embodiments of the invention

[0132] • CALCIUM = Ca

[0133] • CALCIUM CARB ONATE = C AC03

[0134] • ECU = ELECTROCHLORINATION UNIT

[0135] • FACILITY = EMBODIMENT OF PORTABLE ACID WASHING & NEUTRALIZING FACILITY.

[0136] • See NOTE 2

[0137] • HYDROCHLORIC ACID = HC1

[0138] • HYPO = HYPO SOLUTION = SODIUM HYPOCHLORITE SOLUTION =

[0139] • HYPOCHLORITE = NaOCl

[0140] • LOOP = CIRCULATION LOOP = CONTINUOUS CIRCULATION FLOW LOOP WITH

[0141] • AN ACCELERATED FLOW RATE

[0142] MAGNESIUM = Mg

[0143] MAGNESIUM HYDROXIDE = MG(0H)2

[0144] SALT = NaCl • SODIUM HYDROXIDE = CAUSTIC SODA = NaOH

[0145] • SYSTEM = EMBODIMENT OF HYPO GENERATION TEMPERATURE CONTROL SYSTEM.

[0146] • See NOTE 1

[0147] NOTE 1 AN EMBODIMENT OF A HYPO GENERATION TEMPERATURE

[0148] CONTROL SYSTEM

[0149] This SYSTEM represents the most advanced technology for precise temperature control during artificial brine hypo generation. When hypo is generated and stored at room temperature simultaneously, it offers several unique benefits when compared to conventional artificial brine hypo generation which is known for a significant temperature increase between the inlet (saline solution) and outlet (hypo solution) of the electrolyser. The several unique benefits are:

[0150] • Highest Quality Hypo: Produces the highest quality hypo for drinking water chlorination by eliminating the formation of undesirable chlorites and chlorates

[0151] • Optimal Efficiency: Ensures the most efficient hypo generation regarding electric energy and salt consumption

[0152] • Maximized Operational Lifespan: Maximizes the operational lifespan of the MMO coating on the anode

[0153] • Extended Shelf Life: Provides an optimized shelf life (storage) for the produced hypo

[0154] The system operates as a continuous circulation flow loop with an accelerated flow rate. It consists of the following hydraulically series-connected components: the electrolyser, hypo tank, circulation pump, heat exchanger and interconnecting piping. The continuous circulation flow loop includes four independently controlled suction lines on the suction side of the circulation pump and one feed line downstream of the circulation pump, each serving the following purposes:

[0155] • Suction Line 1 (LI): The main suction line from the hypo tank

[0156] • Suction Line 2 (L2): A secondary suction line for fresh water

[0157] • Suction Line 3 (L3): A secondary suction line for saturated brine

[0158] • Suction Line 4 (L4): A secondary suction line for acid washing chemicals such as HC1 and NaOH

[0159] • Feed Line 1 (labels 4, 1, 110, 109, 108, 102, 104 correspond to FEED LINE 1 different numbers are used to label different positions of the feed line): The main feed line, a single line downstream of the circulation pump, running through the primary side of the titanium plate heat exchanger to the electrolyser and back to the hypo tank. It carries the cumulative flow from all the active suction lines (all independently controlled).

[0160] The secondary side of the titanium plate heat exchanger is dedicated to an external coolant, ensuring precise hypo temperature control within the continuous circulation flow loop. Four temperature sensors are strategically placed at the inlets and outlets of both the primary and secondary sides of the heat exchanger to monitor all relevant temperatures. An optional fifth temperature sensor placed at the electrolyser outlet may also be beneficial. These readings are displayed on the HMI, enabling operators to accurately control the flow rate of the external coolant to maintain a precise hypo generation temperature anywhere between 15 °C and 25 °C.

[0161] The system effectively addresses all the inefficiencies and decomposition issues associated with too high or too low temperatures in artificial brine hypo generation. It ensures the highest quality hypo for drinking water applications by eliminating the formation of undesirable by-products such as chlorites and chlorates, offers the most efficient hypo generation, optimizes the operational life of the MMO coating on the anode, and provides the longest possible hypo shelf life.

[0162] HEATING INSTEAD OF COOLING

[0163] The same hypo generation temperature control system can also be utilized in reverse, applying an external heating source instead of an external coolant to heat the inlet feed saline solution (comprising feed fresh water and feed saturated brine) to the optimal range of 15°C to 25°C. This functionality is particularly advantageous in freezing conditions, such as those found in very cold countries. By initially heating the solution to within this temperature range, the system ensures stable and efficient hypo generation. Once the target temperature of 15 °C to 25 °C is reached, precise temperature control can be maintained using either the external heating source, the external coolant, or a combination of both. This dual capability ensures the system's versatility and reliability across varying environmental conditions. NOTE 3 UNDESIRABLE CHLORITES AND CHLORATES IN PUBLIC DRINKING WATER: COMPARING COMMERCIAL GRADE SODIUM HYPOCHLORITE WITH ONSITE ARTIFICIAL BRINE HYPO GENERATION AS PER NOTE 1

[0164] The health risks of undesirable chlorites and chlorates in public drinking water are basically as follows:

[0165] • Chlorites:

[0166] Can cause oxidative damage to red blood cells, potentially leading to hemolytic anemia. Chronic exposure may affect the nervous system and cause developmental issues in infants. The U.S. Environmental Protection Agency (EPA) sets a maximum contaminant level (MCL) of 1.0 mg / L for chlorite in drinking water.

[0167] • Chlorates:

[0168] Can inhibit iodine uptake, affecting thyroid function and potentially leading to hypothyroidism. Prolonged exposure may impact kidney function and cause reproductive issues. The World Health Organization (WHO) suggests a provisional guideline value of 0.7 mg / L for chlorate in drinking water.

[0169] COMMERCIAL GRADE SODIUM HYPOCHLORITE

[0170] Typically available at concentration of 10% = 100,000 ppm C12

[0171] • These high concentrations can lead to increased formation of chlorates

[0172] • Higher risk of degradation during transport and storage, leading to higher chlorite and chlorate levels.

[0173] ARTIFICIAL BRINE HYPO GENERATION

[0174] In this case, artificial brine hypo generation is carried out using an EMBODIMENT OF HYPO GENERATION TEMPERATURE CONTROL SYSTEM as described in NOTE 1. This process involves generating hypo using high-purity salt and high-purity water, typically at a concentration of 0.8% (8,000 ppm C12) and where hypo generation and storage are strictly maintained at 15°C to 25°C. The benefits are:

[0175] • Reduced Chlorate Formation: Lower concentrations and controlled production conditions help to minimize the formation of chlorates

[0176] • Minimized Degradation: Fresh production of hypochlorite minimizes the risk of degradation, resulting in fewer by-products such as chlorites and chlorates

[0177] CONCLUSION

[0178] By comparing commercial grade sodium hypochlorite with onsite artificial brine hypo generation (as per NOTE 1), it is evident that onsite hypo generation offers significant benefits in reducing harmful by-products and maintaining water quality ensuring the safety and quality of public drinking water.

[0179] NOTE 4 COMPARING ARTIFICIAL BRINE HYPO GENERATION AT APPROXIMATELY 45°C VS. STRICTLY MAINTAINED AND STORED AT 15°C to 25°C

[0180] Artificial brine hypo generation and storage at approximately 45 °C:

[0181] This is typically with conventional artificial brine electrochlorination and without applying the embodiment of the HYPO GENERATION TEMPERATURE CONTROL SYSTEM - see NOTE 1:

[0182] • Higher Decomposition Rate: Generating and storing hypo at approximately 45°C significantly increases the decomposition rate of sodium hypo into chlorates and chlorites

[0183] • Reduced Quality: The increased temperature accelerates the formation of undesirable by-products, leading to lower quality hypo for drinking water disinfection

[0184] • Shorter Shelf Life: The hypo solution has a shorter shelf life due to the rapid formation of chlorates and chlorites, making it less effective over time

[0185] • Safety Concerns: Higher concentrations of chlorates and chlorites in drinking water pose greater health risks, including potential impacts on the thyroid and red blood cells. Artificial brine hypo generation strictly maintained and stored at 15 °C to 25 °C

[0186] This is only possible when applying the embodiment of HYPO GENERATION

[0187] TEMPERATURE CONTROL SYSTEM - see NOTE 1:

[0188] • Optimal Quality and Stability: Helps maintain the stability of the hypo solution, minimizing the degradation into chlorates and chlorites

[0189] • Lower Decomposition Rate: At lower temperatures, the rate of decomposition of sodium hypo is reduced, resulting in fewer undesirable by-products

[0190] • Increased Shelf Life: The hypo solution has a longer shelf life due to the reduced formation of by-products that can accelerate decomposition

[0191] • Efficiency: The generation process is more efficient

[0192] CONCLUSION

[0193] • Artificial brine hypo generation strictly maintained and stored at 15 °C to 25 °C significantly improves the quality and stability of the hypo solution

[0194] • It reduces the formation of harmful by-products, ensuring safer drinking water

[0195] • Conversely, artificial brine hypo generation at higher temperatures, around 45 °C, lead to increased decomposition, lower quality, and greater health risks due to the formation of chlorates and chlorites

[0196] • Therefore, strict temperature control as with the embodiment of the HYPO GENERATION TEMPERATURE CONTROL SYSTEM is preferred for optimal artificial brine hypo generation and storage

Claims

CLAIMS1. A system for producing hypochlorite, comprising: an electrolyser with an inlet for receiving a saline solution and an outlet for the electrolysation products which include hydrogen and hypochlorite; a tank for separating hydrogen from hypochlorite, and a conduit for facilitating the flow of hydrogen and hypochlorite from the electrolyser to the tank; wherein the system further comprises a further conduit from the tank to the electrolyser to facilitate the circulation of hypochlorite from the tank to the electrolyser; wherein the system further comprises a heat exchanger which receives hypochlorite from the further conduit; whereby the temperature of the hypochlorite is adjusted prior to returning to said electrolyser.

2. The system according to claim 1, wherein the system comprises a pump for driving the circulation of hypochlorite between the tank and the electrolyser.3.The system according to claim 2, wherein a mixer is provided prior to the pump; the mixer being configured to allow the addition to the flow of hypochlorite of one or more of the following: a saline solution, a cleaning solution or fresh water.

4. The system according to claim 3, wherein the mixer mixes a saline solution and fresh water to the flow of circulating hypochlorite.

5. The system according to any one of the preceding claims, wherein the saline solution is an artificial brine solution.

6. The system according to any of the preceding claims, wherein the heat exchanger comprises titanium plates.

7. The system according to any of the preceding claims, wherein the heat exchanger comprises a primary heat exchanger and a secondary heat exchanger; the secondary heat exchanger comprises an auxiliary source of coolant.

8. The system according to claim 7, wherein the secondary heat exchanger incorporates one or more of the following: an electric chiller, an evaporative chiller and an adiabatic chiller.

9. A system for producing hypochlorite, comprising: an electrolyser with an inlet for receiving a saline solution and an outlet for the electrolysation products which include hydrogen and hypochlorite; a tank for separating hydrogen from hypochlorite, and a conduit for facilitating the flow of hydrogen and hypochlorite from the electrolyser to the tank; wherein the system further comprising a further conduit from the tank to the electrolyser to facilitate the circulation of hypochlorite from the tank to the electrolyser; the further conduit comprising a pump for driving the circulation of hypochlorite from the tank to the electrolyser; the pump being configured to draw in a saline solution for causing the circulation of the saline solution in conjunction with the hypochlorite solution to the electrolyser.

10. The system of claim 9, wherein a mixer is provided prior to the pump; the mixer being configured to allow the addition to the flow of hypochlorite of one or more of the following: a saline solution, a cleaning solution or fresh water11. The system of claim 10, wherein the mixer mixes a saline solution and fresh water to the flow of circulating hypochlorite.

12. The system of either claim 10 or claim 11, further comprising a brine tank and a flow line provided between the brine tank and the mixer through which a saline solution is drawn into the hypochlorite flow.

13. The system according to any one of claims 9 to 12, wherein the system further comprises a heat exchanger which receives hypochlorite from said further conduit; whereby the temperature of the hypochlorite is adjusted prior to returning to the electrolyser.

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