Patent Application
20180290904
The present invention relates to a method and a system for producing electrolyzed water under optimum processing conditions.
The electrolysis of solutions containing ionic salts is an integral part of the process for producing electrolyzed water. Electrolysis of the solutions produces a range of active molecular and ionic species in the electrolyzed water, including in some cases O3 and HOCl.
The production of active species is determined by a number of factors, including:
In many applications, in for example the food and agriculture or horticulture industries, the concentrations of salts have to be limited due to potential sensitivities to high salinity solutions. There are also high capital and operational costs involved in the production of electrolyzed water, and it is therefore desirable to minimise the:
There is therefore a need for a system and a method for the production of electrolyzed water with improved efficiency whilst optimising the production of active species.
According to a first aspect of the present invention, there is provided an electrolysis system for producing an electrolyzed water composition, the system comprising:
The system may further comprise a heater operable to supply heat to the electrolyte solution feed stream and/or the electrolyte solution within the cell. The control system is preferably further operable to control the heater so as to control the temperature of the electrolyte solution. The control system is preferably operable to maintain the temperature of the electrolyte solution/electrolyte solution feed stream at a predetermined temperature or within a predetermined temperature range so as to optimise the conductivity for a given specific concentration of electrolytes, whilst also minimising heat related degradation of the active species, in order to produce an electrolyzed water feed stream having an optimum concentration of active molecular and ionic species. The control system is preferably operable to control the temperature of the electrolyte solution and/or electrolyte solution feed stream is between 25° C. and 40° C. The control system is preferably operable to control the power supply in dependence on the salt concentration and the temperature of the electrolyte solution within the cell to provide a predetermined voltage to the cell, in which the predetermined voltage corresponds to the minimum voltage required for the electrolyte solution at that temperature in order to provide an optimum concentration of active species within the electrolyzed water.
The system may further comprise a clean water supply operable to deliver a clean water feed stream to the electrolyzed water feed stream to produce an electrolyzed water composition feed stream.
The control system is preferably further operable to control the relative flow rates of at least one of the electrolyzed water feed stream, the clean water feed stream, and the electrolyzed water composition feed stream.
The system may further comprise a mixing chamber in fluid communication with the electrolyzed water feed stream and the clean water feed stream.
The system may further comprise at least one flow regulator for controlling the relative flow rates of at least one feed stream.
The electrolytic flow cell may for example be a parallel flow cell.
According to a second aspect of the present invention, there is provided a method for optimising the production of an electrolyzed water composition, comprising:
The method may further comprise heating the electrolyte solution within the electrolytic cell. The method may further comprise heating the electrolyte solution feed stream. The method may further comprise operating the control system to control the temperature of the electrolyte solution feed stream and/or the electrolyte solution within the electrolytic cell. Preferably, the method operates the control system to control the temperature of the electrolyte solution feed stream and/or electrolyte solution within the cell to a temperature between 25° C. and 40° C. so as to optimise the conductivity of the electrolyte solution whilst minimising heat degradation of active species in order to produce an electrolyzed water feed stream comprising an optimum concentration of active species. The method preferably further comprises operating the control system to control the power supply in dependence on the salt concentration and the temperature of the electrolyte solution within the cell to provide a predetermined voltage to the cell, in which the predetermined voltage corresponds to the minimum voltage required for the electrolyte solution at that temperature in order to provide an optimum concentration of active species within the electrolyzed water.
The method may further comprise combining a feed of the electrolyzed water with a clean water feed stream. The method may further comprise combining and mixing the feed streams of the electrolyzed water and clean water within a mixing chamber.
The method may further comprise operating the control system to control the relative flow rates of at least one of: a feed stream comprising the electrolyte solution; the electrolyzed water feed stream, and the clean water feed stream, and any combination thereof.
With reference to
The reservoir 2 is in fluid communication with the electrolytic flow cell 4. The cell 4 comprises between 3-10, for example eight, electrodes (not shown). The electrodes are boron-doped diamond electrodes. It is however to be understood that the cell may contain any suitable number of electrodes, and that the electrodes may be made of any suitable material.
The electrolytic cell comprises a casing, between 3 to 10, for example eight, boron doped diamond electrodes (BDEs) located within the cell, and metal ‘contact plates’ used for transmitting charge across the electrolyte solution.
The BDEs are sheet-like components and are provided in a stack of between 3-10, for example eight, sheets. Each sheet is located at a fixed distance away from an adjacent sheet. The distance between adjacent sheets of BDEs provides a cell gap, which is preferably less than 5 mm, for example between approximately 2 and 3 mm. The BDEs are provided in a plastic frame. The BDEs transmit charge across the electrolyte solution, inducing a strong dipole and creating positively and negatively charged radicals on alternate surfaces of the diamonds.
The electrolyte solution may be introduced into the electrolytic cell in any suitable manner so as to produce electrolyzed water composition in a continuous process or in a batch process. In the continuous process, the electrolyte solution may be introduced at a suitable flow rate, such as for example at a flow rate in the range of from 0.1 to 100 l/min, for example in the range of from 3 to 5 l/min. In the batch process, the electrolyte solution may have a flow rate of approximately 16 l/min.
The electrodes (not shown) are connected to a power supply unit 11 operable to provide an over-potential to the electrolyte solution within the cell to produce an electrolyzed water feed stream 15 comprising a plurality of active molecular and ionic species. The feed stream 15 is in fluid communication with a mixer 18.
The system also comprises a pure water reservoir 16 in fluid communication with the mixer 18. The mixer 18 is a venturi/controlled mixer for mixing the electrolyzed water feed stream 15 with the pure water feed stream 14. It is to be understood that any suitable mixer can be used.
The system 1 also comprises a heater 6 located between the reservoir 2 and the electrolytic flow cell 4. The heater 4 is arranged to heat the electrolyte solution feed stream 13, to a predetermined temperature or to within a predetermined temperature range as and when required, as it flows from the reservoir 2 to the flow cell 4.
The system 1 also comprises flow regulators 10, 12 arranged to independently adjust the flow rates of the electrolyte feed stream 13 and the clean water feed stream 14 from the pure water reservoir 16.
The system 1 further comprises a control system 8 operable to control the power supply unit 11 so as to control the voltage applied across the at least one pair of electrodes. The control system 8 is also operable to control the heater 6 so as to control the temperature of the electrolyte feed stream as it enters the cell 4. It is to be understood that the heater can be provided in any suitable location to provide heat to the electrolyte feed stream and/or electrolyte within the flow cell 4. For example, the heater may be arranged to heat the electrolyte when it is present within cell 4. The control system 8 is also operable to control the flow regulators 10, 12 to independently control the flow rate of the respective feed streams 13, 14.
In a preferred embodiment, excess heat from the power unit can be supplied to the electrolytic cell to pre-heat the electrolyte solution to further optimise power usage by the system. This may be controlled by adjusting the power applied to thermoelectric pumps or heat coils whose heat sink (heat exchanger 19) connects the power unit 11 to the heating element arranged to heat the electrolyte solution.
The control system 8 in this embodiment is a single rotary knob to control the voltage applied across the electrodes, and the relative flow rates of the electrolyte solution, the electrolyzed water, the clean water feed, and/or the temperature of the electrolyte solution In order to provide a predetermined voltage across the electrodes in which the predetermined voltage is the minimum voltage required for the electrolyte solution at that temperature in order to provide an optimum concentration of active species within the electrolyzed water.
The control knob setting ranges from ‘clean water’ to ‘full strength’. Switching to ‘clean water’ would cause the flow rate, heating and voltage to be applied to zero.
The output from the mixer would be clean water. Switching to ‘full strength’ would mean that the flow rate of clean water to the mixer would be zero. The heating of the electrolyte solution and the voltage applied would be at their maximum settings. Intermediate settings between ‘clean water’ and ‘full strength’ would use different ratios of relative flow rates between the electrolyzed water feed and clean water into the mixer, and varying temperatures applied to the electrolyte solution, and varying voltage applied across the electrodes, which would generate electrolyzed water compositions comprising increasing concentrations of active species, increasing in a linear manner, whilst keeping the output solution's salt concentration within a preset window.
Although this embodiment comprises a single control knob, it is to be understood that the control system 8 may be operable by a digital display.
High salinity solutions require significantly less power to provide a given concentration of active species. Preferably, the electrolyte solution is a high salinity salt solution, for example a solution comprising a salt concentration of at least 20 g/l. The present invention therefore provides a method and system with improved energy efficiency and reduced cost implications for providing electrolyzed water compositions having a given concentration of active species.
The system of the present invention enables high concentration salt solution to be electrolyzed within the cell (optionally at a predetermined temperature and flow rate) whilst requiring a consistent, predetermined, minimum voltage to be applied across the electrodes in order to provide electrolyzed water having a predetermined concentration of active species.
The system and method of the present invention therefore involves the use and/or production of high salinity solutions which are likely to be corrosive, irritant and/or phytotoxic. The system of the present invention therefore optionally includes a mixing chamber, in which the high salinity electrolyzed water composition is diluted immediately after production within the chamber with pure water. The electrolyzed water composition is preferably diluted immediately after production and at the point of delivery to minimise the degradation of actives in the EW solution. The method and system of the present invention therefore enable the desired concentration of active species to be produced within the electrolyte solution whilst minimising the required power supply and/or electrode size, and also providing an output electrolyzed water composition with salt concentrations which are safe to deliver.
The present invention provides a system and method for the production of electrolyzed water compositions with reduced production costs. As there is a reduced power requirement to operate the system, there are lower operating costs and a reduced carbon footprint associated with the system and method of the present invention. Due to the optimisation of the process parameters the size and cost of the electrolytic cell can be reduced.
With reference to
The sodium chloride solutions investigated had conductivity values, directly related to the concentration of the salt solutions, of 0.55 mS/cm, 1.00 mS/cm, 2.00 mS/cm, 4.40 mS/cm and 9.98 mS/cm respectively. The conductivity of a solution increases as the concentration of the salt solution increases.
It can be seen from
It can be seen for example that the power required to provide electrolyte water having a predetermined concentration of active species is approximately a factor of 6 greater for a sodium chloride solution having a conductivity value of 0.55 mS/cm than for a sodium chloride solution having a conductivity value of 10 mS/cm.
The control system of the system of the present invention is therefore operable to control the power supplied to the electrodes within the cell in dependence of the concentration of the electrolyte solution, for example the conductivity of the electrolyte solution, in order to optimise the voltage required to produce electrolyzed water having a given concentration of active species. The present invention therefore provides a system and method with improved energy efficiency (and reduced cost implications) for providing electrolyzed water having a given concentration of active species.
Sodium chloride solutions were introduced into the reservoir of the system of
It is also however known that the temperature of the solution is a major contributing factor towards the instability of electrolyzed water compositions. Preferably, the temperature of the electrolyte solution is maintained within a temperature range of between 25° C. and 40° C. at which the lowest power can be supplied to the cell in order to generate the highest concentration of active species for a given charge density and salt concentration.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1421871.3 | Dec 2014 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2015/053716 | 12/4/2015 | WO | 00 |
