WO2011066834A1

WO2011066834A1 - Regulation of an electrochemically produced fluid in response to changed demands

Info

Publication number: WO2011066834A1
Application number: PCT/DK2010/000163
Authority: WO
Inventors: Kurt Rudolph Renner; Hardy Peter Jepsen
Original assignee: Danish Clean Water A/S
Priority date: 2009-12-02
Filing date: 2010-12-01
Publication date: 2011-06-09

Abstract

This invention relates to the production of a fluid, especially in an electrochemical cell, where the fluid in the preferred embodiment is a fluid for disinfection or sterilization of any kind of water where bacterial count has to be controlled such as industrial food processing systems like pasteurizers, where the disinfecting fluid may contain an aqueous solution of sodium chloride of an electrochemically processed or produced anolyte and an electrochemically processed or produced catholyte. The invention especially relates to a method and device for regulation of the output of the disinfection fluid according to a demand, or more specifically to a changing demand.

Description

REGULATION OF AN ELECTROCHEMICALLY PRODUCED FLUID IN RESPONSE TO CHANGED DEMANDS. This invention relates to the production of a fluid, especially in an

electrochemical cell, where the fluid in the preferred embodiment is a fluid for disinfection or sterilization of any kind of water where bacterial count has to be controlled such as industrial food processing systems like pasteurizers, where the disinfecting fluid may contain an aqueous solution of sodium chloride of an electrochemically processed or produced anolyte and an electrochemically processed or produced catholyte. The invention especially relates to a method and apparatus introducing the method for regulation of the output of the disinfection fluid according to a demand, or more specifically to a changing demand

Background of the invention

When an aqueous solution containing sodium chloride is electrolysed in an electrochemical cell, the type and the amount of electrolysis products are determined by several different parameters. These parameters include, among others, the initial concentration of sodium chloride in the aqueous solution to be electrolysed, the presence of impurities in said aqueous solution and the actual size of the applied potential. Another important parameter is whether a diaphragm separates the anode and the cathode.

The electrochemical process of water involves the exposure of water and natural (or added) salts to a substantial difference in electrical potential. If an anode (+) and a cathode (-) are placed in pure water and a direct current is applied, electrolysis of water occurs at the electrodes, leading to the breakdown of water into its constituent elements - gaseous oxygen and hydrogen.

Electroplating is a similar process, where chromium salts are added to water, a difference in potential is applied, and the chromium is deposited onto the material attached to the cathode. If sodium chloride (NaCI), or table salt, is used as a solution, the dominant electrolysis end product is various forms of chlorine and sodium hydroxide. In the recent decades electrochemically processed or produced solutions have been produced in a diaphragm cell. Hence, an anolyte is produced at the anode in the anode chamber, which is separated from the cathode chamber by the diaphragm. The catholyte is produced at the cathode. Subsequently, the catholyte and the anolyte may be used separately or as a mixture.

It is well-known that the anolyte may be used as a biocide to kill bacteria, algae and fungi in drinking water and industrial water. This effect is assigned to the presence of H202, CI02, HCIO, HCI03, HCI, CI2, 02, 03, H+, H3O+, CIO-, CI-, and free radicals. The catholyte may be used as a cleaning and/or bleaching solution. Typically the catholyte contains species, as H2O2- and OH-. Due to the electrochemical reactions, which occur at each of the two electrodes, the final pH of the anolyte will be acidic whereas the final pH of the catholyte will be alkaline. Hence, in some cases it may be advantageous to mix the anolyte and the catholyte in order to produce a solution of neutral pH. Such mixed solutions may be used as disinfectants or sterilizing solutions.

It is also well-known that the efficiency of the salt conversion in the

electrochemical cell will depend on parameters like flow rates of fluids to the cell, and of the concentration of the salt in the flows.

For example, if the flow rate is increased, the salt conversion efficiency drops and vice versa. This is simply caused by the fact that a higher flow rate would give the salt less time to react. A natural choice if a demand, such as the needed delivered amount, or flow rate, of the produced output fluid is changed would be simply to change the flow rates in the apparatus. However, this would lead to a changed amount of salt that would, if the flow rate was increased, lead to an increased waste of the substances in the apparatus, since a smaller amount would be utilized in the production of the output disinfection fluid. Another disadvantage is that the composition of the final output disinfection fluid might have an unintended and even undesired composition, meaning concentrations of the anolyte and catholyte.

Another issue is that at least some of the active substances (such as 03, CIO2 and H2O2) are highly volatile, meaning they are only present in the order of a few days or will more or less have disappeared within hours. This makes it undesirable to produce for storage reservoirs for later use, or even for distribution. The best way fully to utilize the output disinfection fluid, is at least substantially to produce it continuously as it is being consumed, and feed it directly to the apparatus or the like where it is to be used. The procedure or process of disinfecting a system (e.g. industrial food

processing systems, water supplies of domestic water etc.) usually is done by feeding an amount of the disinfection fluid to the system from a reservoir at a rate proportional to a operation rate (usually just a flow rate of water) of the system, this rate in the following being referred to as the consumption rate. A sensor of the system measures e.g. the water flow rate, and disinfection fluid is fed from a reservoir to the system at a consumption rate proportional to this water flow rate. However, due to the volatile active substances, this reservoir would preferably have to be filled more or less as it is being emptied, so that the 'age' of the stored disinfection fluid is relatively short.

It is a well known fact within many areas of technology, that is it is energetic most favourable to operate at a continuously level rather than constantly changing the operational speed, de-accelerate, accelerate etc. Present apparatuses typically produces to a reservoir comprising a 'high level' and 'low level' sensor, the starting to produce output disinfection fluid when the 'low level' sensor is activated, and stopping again when the 'high level' sensor is activated. Hereby is achieved that the production constantly is started and halted, and this is not very energy efficient. The object of the present invention thus is to introduce a method to ensure a more optimized production of an output disinfection fluid, and where this is produced in response to a changing demand. This means to produce it in a manner where the disinfection fluid is produced running to keep a constant level within the reservoir containing the disinfection fluid, rather than within a maximum and minimum range. Thus eliminating the energy unfavourable constant starting and closing of the production. In the same manner another object is solved too, the object to ensure

substantially freshly produced disinfection fluid produced and that the apparatus is adapted so that this freshly produced disinfection fluid may be feed directly to where it is to be used. The present invention relates to the method as well as the means for and the apparatus itself.

The output fluid in the preferred and described but non-limiting embodiment is a disinfection fluid, or sterilizing fluid, and is therefore in a non-limiting manner referred to as such in the following .

Summary of the invention

The object of the present invention thus is resolved by introducing means to correlate the salt concentration of the salt water entering an electrochemical cell in response to a change in flow rates to meet a change in some demand.

For example, in an apparatus having a main water flow with a first flow rate being mixed with a salt intake flow with a second flow rate, then, if the first and second flow rates were changed by the same fractions, the salt conversion efficiency would change. If the flow rates were raised, the salt conversion would fall and vice versa. This is simply caused by the fact that a higher flow rate would give the salt less time to react. This is solved by introducing an apparatus for producing an output solution fluid comprising an electrochemically activated anolyte and catholyte, the apparatus comprising an electrochemical cell having an anode chamber and a cathode chamber and a fluid communicating network communicating a main water supply flowing with a first flow rate and a salt supply flowing with a second flow rate, wherein, the apparatus further comprises means to individually regulate the first and second flow rates, and where the apparatus regulates to a demand, or a changing demand, by regulating the first flow rate by a first fraction and the second flow rate by a second fraction.

The present invention further relates to the method of regulating the first flow rate at a first fraction and the second flow rate at a second fraction. More specifically, the present invention relates to the apparatus being able to change the output to meet a changing need or demand.

In a first preferred embodiment, the changing demand is the amount, or flow rate, of the produced output fluid. .

In a related example, the changing demand is to continuously equalize the actual consumption of the anolyte and/or the catholyte in the system where the disinfection fluid is being used, where the disinfection fluid is only produced in response to the demand, rather than just leading a demanded fraction of the total produced amount of disinfection fluid to where it is being used.

In another example of the present invention, the changing demand is linked to keeping a substantially constant concentration of the anolyte and/or the catholyte at some destination of use of the output fluid.

In another example of the present invention, the changing demand is set by the user of the apparatus choosing the desired output flow or composition

(concentration of the anolyte and/or the catholyte) of the produced disinfection fluid. This would imply a change of the process parameters, such as the flow rates, the salt concentration of the fluid entering the electrochemical cell, and the operation parameters of the electrochemical cell, e.g. the voltage. In yet another example of the present invention, a changing demand includes a changing amount of salt in a salt reservoir of the apparatus (the brine), in a manner where, when the amount of salt is too low fully to saturate the salt water, then the salt water flow will be increased and a alarm will be set to re-fill the brine with fresh salt. This ensures that the system will not halt due to lack of salt in the brine, but will keep the system running un-disturbed for a while until the brine is re-filled.

In the preferred embodiment of the present invention, the important content in the anolyte is a result of the ions which are electrolyzed in the cell, whereas at least two ions are selected from the following list comprising the potassium ion, sodium ion, ammonium ion, chloride, bromide, sulphate, nitrate, carbonate and amine.

For all of these examples of changing demands, the changes are meet by changing the flow rates, however, as described above, this leads to a change in the conversion efficiency of the salt, to a change in the composition of the disinfection fluid and possible even to a change in undesired parameters such as the pH value. The idea is to include means permitting the apparatus to perform a variable control of the flows of fluids in the apparatus, such as, but not limited to, variable valve means or variable pumping means, as they are well known in the art, such means at least regulating the flow rates of the main flow and the salt intake flow.

Thus, to ensure that the first and second flow rates may be regulated with first and second fractions respectively, a more specific embodiment of the present invention also relates to an apparatus, wherein the apparatus comprises first flow regulating means to regulate the first flow rate, where the first flow regulating means is a variable valve and/or a variable dosing pump, and where the apparatus further comprises second flow regulating means to regulate the second flow rate, where the second flow regulating means is a variable valve and/or a variable dosing pump.

One may say that the apparatus operates under a set of demands, being a number of individual demands each to be satisfied. Such individual demands could, for example, be that the output fluid needs to have a certain constant (but optionally adjustable) composition / concentration of the active substances, that the output fluid has to flow at a certain flow rate (or in other words, the apparatus is set to deliver a set amount of fluid), to operate with a certain (e.g. minimum) salt conversion efficiency, etc. The invention therefore also relates to changes of the first and the second fractions, and optionally and/or additionally other process parameters, to ensure that the set of demands is satisfied.

Said in a more general manner, when the apparatus operates according to a set of demands, it has to satisfy each of the individual demands. If one or more demands are changed, then the first and second fractions are calculated so that the new set of demands is satisfied despite the change in some of the individual demands.

The idea is also to use the fact that the appartus will run predictably knowing the actual process parameters of the apparatus, such as the flow rates, the voltage of the electrochemical cell, the salt concentration etc.

The invention thus relates first of all to a change of the first flow with a first fraction and the salt intake flow (second flow) with a second fraction being different from the first fraction, where the respective fractions are calculated to ensure a constant composition of the output fluid,, and at the same time meets possible new set of combined demands, the calculations being based on the knowledge of the actual process parameters, and how the relative change of the main flow and the salt intake flow would influence the salt conversion efficiency and the set of combined demands.

To ensure this, the apparatus operates by a method wherein the first fraction and the second fraction are controlled in such a way that a change in the second fraction is followed by a change in the first fraction where the change in the first fraction follows another rule than the change in the second fraction.

One such rule might be that the second fraction is higher than the first fraction, meaning that the salt intake flow is regulated at a higher fraction than the main water flow, or vice versa.

In order to track the concentration of the mixed fluid (being the fluid to enter the electrochemical cell and thus being a mix of the main flow and the salt intake flow), the apparatus in yet a further embodiment comprises a conductivity sensor for measuring the conductivity of the mixed fluids, this being a direct function of the salt concentration in the mixed fluid.

In one embodiment, this measured conductivity is used to regulate one or both of the first and second flow regulating means.

Since the needed correction of first and second flows with a first and second fraction respectively is predictable, the apparatus in another preferred embodiment includes a programmed table giving the relation of control of the apparatus to apparatus parameters, such as first flow rate, second flow rate, voltage over electrolyzes cell, amperage through electrolyzes cell, flow temperature, amount of catholyte taken away before second passage in electrolyzes cell and concentration of anolyte. In a similar manner in another or additional embodiment, the first and second fractions are modulated by a formula developed from minimum two running points or from a multidimensional dataset. The procedure or process of disinfecting a system (e.g. industrial food processing systems, water supplies of domestic water etc.) usually is done by feeding an amount of the disinfection fluid to the system from a reservoir at a rate proportional to a operation rate (usually just a flow rate of water) of the system, this rate in the following being referred to as the consumption rate. A sensor of the system measures e.g. the water flow rate, and disinfection fluid is fed from a reservoir to the system at a consumption rate proportional to this water flow rate. However, due to the volatile active substances, this reservoir would preferably have to be filled more or less as it is being emptied, so that the 'age' of the stored disinfection fluid is relatively short.

In the main preferred but not limiting embodiment of the present invention, the disinfection fluid is fed to a reservoir being coupled to a system, the system consumes the disinfection fluid from this reservoir at a rate proportional to the operation rate (such as a flow rate of water) of the system, this flow rate referred to as the consumption rate. A sensor of the consuming system measures e.g. the water flow rate, and disinfection fluid is fed from a reservoir to the system at a flow rate proportional to this water flow rate. This means to produce it in a manner where the disinfection fluid is produced running to keep a constant level within the reservoir containing the disinfection fluid, rather than within a maximum and minimum range. Thus eliminating the energy

unfavourable constant starting and closing of the production.

In this embodiment the first flow rate, the main flow rate of the system of the present invention, is regulated linearly / proportional to the consumption of the disinfection fluid in the reservoir, again depending linearly on e.g. the flow rate of water in the consuming system. The second flow rate is however changed by a third order relationship / equation to the consumption rate of the disinfection fluid in the reservoir, being a consequence of regulating the system such that the measured conductivity (and the salt water concentration) is regulated by a second order relationship / equation. Figures:

Fig. 1 shows a schematic view of the disinfection apparatus according to the invention.

Figs. 2A-C shows measurements compared to calculated values of the relationship of the main flow in the apparatus according to the present invention, to the conductivity, salt concentration and salt flow rate respectively, for a 40 litres electrochemical cell.

Figs. 3A-C shows measurements compared to calculated values of the relationship of the main flow in the apparatus according to the present invention, to the conductivity, salt concentration and salt flow rate respectively for a 120 litres electrochemical cell.

Detailed description

Fig. 1 is a simple schematic illustration of a disinfection apparatus (1) where the present invention may be introduced. The apparatus comprises an

electrochemical cell (2), preferably but not limited to a diaphragm

electrochemical cell, having a cathode chamber (3) and an anode chamber (4). The apparatus further comprises a mixing manifold (5), a softening device (6), and an acid supply such as an acid reservoir (7). A first fluid communication (10) forms a fluidic connection between the cathode chamber (3) and the mixing manifold (5). A second fluid communication (1 1) is fluidly connected to the cathode chamber (3), and has a first branch (11 a) fluidly connected to the anode chamber (4), and a second branch (1 b) fluidly connected to the externals, for example the system where the disinfection fluid is to be used, the consuming system, or a reservoir.

unfavourable constant starting and closing of the production.

The composition and concentration of the output disinfection fluid stored in the reservoir is to be kept constant at an optionally adjustable level.

The mixing manifold (5) is fluidly connected to a salt and water supply (20) through a third fluid communication (12), to the softening device (6) through a fourth fluid communication (13), and to the acid supply (7) through a fifth fluid communication (14).

A sixth fluid communication (15) is fluidly connected to the anode chamber (4) and has a first branch (15a) fluidly connected to the externals, to a reservoir or to the system to be disinfected, and has a second branch (15b) merging with a seventh fluid communication (16), where the seventh fluid communication (16) forms fluidic connection from the softening device (6) and the externals, or a drain.

The softening device (6) is fluidly connected to a water supply through an eighth fluid communication (17).

The apparatus operates by having a main water flow entering from a main water supply (30) at a first flow rate, to the softening device (6) through the eighth fluid communication (17) the filter (21) and a first pressure regulating device (22) ensuring that the water is fed to the softening device (6) at a maximum predetermined pressure, the maximum predetermined pressure preferably being in the range of 2.5 to 7 bar, or more preferable in the range of 3 to 4 bar, or more preferably 3.3 bar.

This softened water then leaves the softening device through the fourth fluid communication (13) and the remains from the softening process are removed through the seventh fluid communication (16). Before entering the mixing manifold (5) the softened water runs through a first flow regulation device (24) ensuring that the softened water enters the mixing manifold (5) with a flow volume possibly set by the actual size of cell (2) and at a proportional rate to the consumption flow. Alternatively in another embodiment, the device (24) is or additionally comprises a second pressure regulating device (24) ensuring that the softened water enters the mixing manifold (5) at a predetermined minimum pressure, the predetermined minimum pressure being in the range of 1 to 2.5 bar, or more preferably in the range of 2 to 2.3 bar, or more preferably 2.2 bar.

In the mixing manifold (5) the softened water is mixed with the saltbrine from the salt supply (20) by the controllable first pumping device (25) through the third fluid communication (12). This mixed fluid is then transported to the cathode chamber (3) through the first fluid communication (10). A conductivity sensor (28) is either positioned at the first fluid communication ( 0), at the inlet of the cathode chamber (3), or inside or at the outlet of the mixing manifold (5), and measures the conductivity of the mixed fluid flowing in the first fluid

communication (10), this being a direct function of the salt concentration of the mixed fluid.

The measured conductivity, and thereby also the salt concentration of the mixed fluid, is used to control the controllable first pump (25), increasing the pumping rate and thereby the flow rate of the saltwater flowing in the third fluid

communication (12), if the conductivity, or salt concentration, gets below a salt concentration set point, and if needed, decreasing the pumping rate if the conductivity, or salt concentration, gets above the salt concentration set point. This pumping rate is then able to estimate when the salt reservoir is close to empty, and, if so, to give a signal or an alarm to the user of the disinfection apparatus (1) to add new salt to the salt supply (20).

In one preferred embodiment of the invention the apparatusdecalcifies at predetermined intervals. This is done by shutting down the supply of salt fed to the mixing manifold (5) and at the same time pumping acid from the acid supply (7) to the mixing manifold (5) by the second controllable pumping device (26) through the fifth fluid communication (14) for either a predetermined, estimated or measured interval of time. This has the advantage that a rather concentrated acid supply (7) may be used, the needed concentration being mixed inside the mixing manifold (5) with the softened water. This gives a number of advantages, such as lowering the needed frequency for a possible acid reservoir (7) to be refilled, but also that a variable acid concentration may be supplied at the decalcification process, depending on the need, the user desire and

programming of the disinfection apparatus( ) (possibly by a tuning button and the like), calculation etc.

The voltage applied to the electrochemical cell (2) is maintained at a

predetermined value, however, as the electrochemical cell (2) calcifies, the resistance increases, meaning that the supplied current decreases. This is measured, and the measurement is used to estimate the calcification of the diaphragm electrochemical cell (2) and starting a decalcification process as described above when some specified level of calcification is reached. The time interval of decalcification may depend on the time to get the measured current below some predetermined value, and the acid concentration may depend on parameters such as the gradient, whereby the current drops during the running process, the desires and programming of the user etc.

In one preferred embodiment of the present invention, the apparatus comprises a buffer reservoir (not shown) fluidly connected to the sixth fluid communication (15), and optionally comprising means for opening and closing this fluidic connection. During decalcification the stored disinfection fluid in the buffer reservoir is then fed to the system to be disinfected or sterilized, either directly by a fluid communication from the buffer reservoir, or by feeding the fluid from the buffer reservoir to the first branch (15a) of the sixth fluid communication (15). Any numbers of valves, fluid communications and the like needed to store, direct and redirect the fluids of such a buffer reservoir construction.

The pH value of the disinfecting fluid preferably needs to be within some span, such as between 5 and 10, or more preferred between 6 and 9, or more preferred between 6 and 8. The disinfection apparatus (1) may have means for the user to define the desired pH value, or the set point pH value, of the disinfecting fluid. Alternatively this set point pH value is predefined in the apparatus. Since this pH value can be calculated with a substantially good certainty, given the parameters, such as the concentration and flow rate of the mixed water, the voltage applied to the electrochemical cell (2) and the electrochemically processed catholyte formed in the cathode chamber (3) being feed to the anode chamber (4), a table may be established and programmed into the apparatus for these relations.

Based on such a table, the disinfection apparatus (1) uses a method to regulate the pH value of the disinfecting fluid by regulating the fraction of

electrochemically processed or produced catholyte being transferred to the anode chamber (4) from the cathode chamber (3) through the second fluid communication (11). The second branch (11b) of the second fluid

communication (11) comprises a first controllable valve (27), so that this first controllable valve (27) may increase and decrease the flow resistance of the second branch (11b), thereby controlling the fraction of the electrochemically processed or produced catholyte that will flow through the second branch (11b), and the fraction that will flow through the first branch (11a) and into the anode chamber (4). In this manner, a first fraction of the electrochemically processed catholyte formed in the cathode chamber (3) may be led to the anode chamber (4) and a second fraction may be led away from the electrochemical cell (2), and the pH value of the disinfecting fluid is regulated by increasing the second fraction and correspondingly decreasing the first fraction or decreasing the second fraction and correspondingly increasing the first fraction in relation to the present pH value relative to the set point pH value.,

The apparatus could advantageously have a tenth fluid communication ( 9) creating fluidic connection from the main water supply (30) to the salt and water supply (20) and/or the softening supply (23), thereby being the water supply for these.

It is also well-known that the efficiency of the salt conversion in the

electrochemical cell will depend on parameters like the flow rates, both the actual rates, and the relative flow rates of the individual mixing fluids being feed for example to the mixing manifold (5), and of the concentration of the salt in the flows, especially the mixed fluid. The higher the flow rate of the mixed fluid entering the electrochemical cell (2), given some constant salt concentration of this mixed fluid, the lesser time for converting the salt, thus giving a lower efficiency.

Therefore, there is a need of regulating the salt concentration of the mixed water entering the electrochemical cell (2) at a different power than the regulation of the flow rate wherewith it enters the cell (2), in order to corrugate for this conversion.

In one simple example, the calculation of the first fraction to regulate the main water flow is regulated linearly to the changing demand (e.g. a change of flow rate of a water pipe for domestic water) and the second fraction to regulate the salt intake flow are is regulated at least to a power being at least one higher than the main water flow, or more preferable at least two orders higher. The regulation however might also be much more advanced including any combination of powers and relations of other parameters in the regulation, such as the first and second flow rates, change in temperature, change in pH values for output fluid or the main water flow, such as of the mixed water supplied to the electrochemical cell (2), etc.

The present invention takes the advantage of the apparatus having means for adjusting flow rates, such as first the flow regulation device (24) regulating the main water supply (the first flow regulating device (24) could be any device able to regulate flow rates, such as a variable valve, variable pumping means etc., as it is well known in the art), and the controllable first pumping device (25) (in the same manner as the first flow regulating device (24), this could be any known device in the art to regulate a flow rate).

These means (24) and (25) are then used to regulate the first flow rate and the second flow rate by a first fraction and a second fraction respectively, according to the rules specified by the apparatus according to the changed demand and the following new set of demands, and by the present operation parameters of the apparatus.

The device would advantageously also include means such as a micro-chip etc. for calculating the new needed first and second fractions, and therefore also the first and second flow rates, and might also comprise a table giving relations needed for the calculations etc.,

Fig. 2A shows four measurement points of the conductivity of the mixed water entering the electrochemical cell (2), which is what is actually being measured in the system measured by conductivity sensor (28). Since the main dominating factor to the conductivity is the salt, this is substantially direct related to the salt concentration and the water temperature. The measuring points are seen substantially to match to a second order equation.

The coefficient Aeon, Bcon and Ccon often will have to be calculated according to an actual setup, and will usually depend on a number of factors such as the actual electrochemical cell (2), the actual consuming system and content of the fluids therein, etc. The variable x is the main water flow rate (first flow rate) and Y is the corresponding conductivity of the mixed water entering the

electrochemical cell (2).

Fig. 2B shows four measurement points for the dependence of the desired salt concentration of the mixed water entering the electrochemical cell (2) to the main flow, where the main flow again reflects the actual demand, the operation (flow) rate of the consuming system. The points are seen substantially matching to an equation going to a power of 2:

The coefficient Asc, Bsc and Csc often will have to be calculated according to the actual setup, and will usually depend on a number of factors such as the actual electrochemical cell (2), the actual consuming system, the water temperature and content of the fluids therein, etc. Again the variable x is the main water flow rate (first flow rate) and Y is the corresponding desired salt concentration of the mixed water entering the electrochemical cell (2).

Fig. 2C shows four measurement points for how the regulation actually is done, by changing the flow rate of the salt water being the second flows rate. This is seen to substantially to match to a third order equation.

3 2

Y = AflowX + BflowX + CflowX + Dflo

Again the coefficient Aflow, Bflow, Cflow and Dflow often will have to be calculated according to a actual setup, and will usually depend on a number of factors such as the actual electrochemical cell (2), the actual consuming system the water temperature and content of the fluids therein, etc. Again the variable x is the main water flow rate (first flow rate) and Y is the corresponding saltbrine (2). The figures 3A-C shows the same as the figures 2A-C, just measured for an 120 litres electrochemical cell (2).

Claims

Claims:

1. An apparatus for producing an output fluid comprising an electrochemically activated anolyte and catholyte, where the apparatus comprises an

electrochemical cell having an anode chamber and a cathode chamber, and a fluid communicating network for communicating at least a main water flow from a water supply at a first flow rate, and a salt intake flow from a salt supply at a second flow rate, where the apparatus further comprises means for individually regulating the first and second flow rates respectively in response to a changed demand.

2. An apparatus according to claim 1, where the first flow rate is regulated by a first fraction and the second flow rate is regulated by a second fraction being different from the first fraction.

3. Apparatus according to claim 2, wherein the second fraction is higher than the first fraction, meaning that the salt intake flow is regulated at a higher fraction than the main water flow.

4. An apparatus according to claim 3, wherein the second flow rate is regulated by a third order relation of the first flow rate.

5. An apparatus according to one of claims 2-4, wherein the concentration of the fluid entering the electrochemical cell is regulated to a second order relation of the first flow rate.

6. An apparatus according to one of the claims 2-5, wherein the changing demand is related to continuously equalize an actual consumption of the disinfection fluid still maintaining its composition constant.

7. Apparatus according to claim 6, wherein the actual consumption is measured by a sensor measuring the volume of output fluid within a reservoir.

8. Apparatus as in any of the preceding claims, wherein the apparatus further comprises a conductivity sensor for measuring the conductivity of the mixed fluids, this being a direct function of the salt concentration in the mixed fluid being used to regulate the first flow regulating means and/or the second flow regulating means.

9. Apparatus as in any of the preceding claims, wherein the apparatus includes a programmed table giving the relation of control of the apparatus to apparatus parameters, first and second flow rates, voltage over electrolyzes cell, amperage through electrolyzes cell, flow temperature, amount of catholyte taken away before second passage in electrolyzes cell and concentration of anolyte

10. The method or apparatus according to any single or combined previously claims, wherein the second flow rate is regulated by a third order relative to the first flow rate.

11. Method to regulate the production of an output fluid comprising an electrochemically activated anolyte and catholyte produced in an apparatus comprising an electrochemical cell, where the output fluid is used at a consumption rate in a system, characterized in that, the method is to mix main water flowing with a first flow rate with salt water flowing at a second rate, and feed to mixed water to the electrochemical cell, where the first flow rate is regulated by a first order equation in dependence to the consumption rate, and the second flow rate is regulated by a third order equation in dependence to the first flow rate.

12. Method according to claim 11 , wherein the conductivity of the mixed fluids is measured, and the regulated such that it is regulated by a second order equation in relation to the first flow rate by regulating the second flow.

13. Method according to claim 11 or 12, where the output fluid is feed to a reservoir comprising a sensor for measuring the volume of output fluid in the reservoir, and where the stored output fluid is feed to a system at a consuming rate, where the apparatus producing the output fluid the signal from the sensor to regulate the first flow rate, and thereby also the second flow rate, in order to keep the volume of the output fluid within the reservoir at a constant level, the level optionally being adjustable.