WO2023186540A1 - Installation de traitement des eaux et procédé destiné au fonctionnement d'une installation de traitement des eaux - Google Patents
Installation de traitement des eaux et procédé destiné au fonctionnement d'une installation de traitement des eaux Download PDFInfo
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- WO2023186540A1 WO2023186540A1 PCT/EP2023/056582 EP2023056582W WO2023186540A1 WO 2023186540 A1 WO2023186540 A1 WO 2023186540A1 EP 2023056582 W EP2023056582 W EP 2023056582W WO 2023186540 A1 WO2023186540 A1 WO 2023186540A1
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- WO
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- Prior art keywords
- water
- conductivity
- hardness
- raw water
- measuring device
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 649
- 238000000034 method Methods 0.000 title claims abstract description 51
- 238000002156 mixing Methods 0.000 claims abstract description 119
- 150000002500 ions Chemical class 0.000 claims abstract description 106
- 238000001556 precipitation Methods 0.000 claims abstract description 73
- 238000005259 measurement Methods 0.000 claims abstract description 47
- 238000005868 electrolysis reaction Methods 0.000 claims description 114
- 230000008859 change Effects 0.000 claims description 67
- 239000000203 mixture Substances 0.000 claims description 64
- 239000002351 wastewater Substances 0.000 claims description 27
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 claims description 22
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 21
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 21
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 12
- 239000011575 calcium Substances 0.000 claims description 11
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 9
- 229910001424 calcium ion Inorganic materials 0.000 claims description 9
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 9
- 238000011088 calibration curve Methods 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000009434 installation Methods 0.000 abstract description 4
- 238000012423 maintenance Methods 0.000 abstract description 4
- 239000000126 substance Substances 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 3
- 230000007774 longterm Effects 0.000 abstract description 2
- 239000003513 alkali Substances 0.000 abstract 1
- 239000003651 drinking water Substances 0.000 description 22
- 235000020188 drinking water Nutrition 0.000 description 22
- 230000008929 regeneration Effects 0.000 description 17
- 238000011069 regeneration method Methods 0.000 description 17
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 11
- 230000036961 partial effect Effects 0.000 description 10
- 230000007704 transition Effects 0.000 description 9
- 230000008569 process Effects 0.000 description 7
- 238000012937 correction Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L calcium carbonate Substances [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- 238000005341 cation exchange Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- -1 alkaline earth metal cations Chemical class 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 150000001768 cations Chemical class 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 3
- 239000001095 magnesium carbonate Substances 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 238000004448 titration Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 235000010216 calcium carbonate Nutrition 0.000 description 2
- 150000003841 chloride salts Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000004851 dishwashing Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000001172 regenerating effect Effects 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QXNVGIXVLWOKEQ-UHFFFAOYSA-N Disodium Chemical class [Na][Na] QXNVGIXVLWOKEQ-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 125000005586 carbonic acid group Chemical group 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000003926 complexometric titration Methods 0.000 description 1
- 238000000402 conductometric titration Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000005115 demineralization Methods 0.000 description 1
- 230000002328 demineralizing effect Effects 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000008233 hard water Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 235000011160 magnesium carbonates Nutrition 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000002826 nitrites Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000008234 soft water Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
- C02F2001/425—Treatment of water, waste water, or sewage by ion-exchange using cation exchangers
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/05—Conductivity or salinity
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/04—Flow arrangements
- C02F2301/043—Treatment of partial or bypass streams
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention
Definitions
- the invention relates to a method for operating a water treatment system and a water treatment system.
- the hardness of water is determined by the concentration of the alkaline earth metal cations dissolved in the water and, in specific applications, also by the concentration of the associated anionic partners, in particular hydrogen carbonate.
- the sum of the concentrations of all dissolved alkaline earth metals (which can be present as carbonates, sulfates, chlorides, nitrites, nitrates and phosphates) is referred to as total hardness.
- the portion that is only bound to carbonic acid is called carbonate hardness (or temporary hardness) and the difference between total hardness and carbonate hardness is called non-carbonate hardness (or permanent hardness), whereby the majority of the total hardness in drinking water is usually present as carbonate hardness.
- hardness generators calcium and magnesium ions essentially contribute to the overall hardness of water. The sum of the concentration of calcium and magnesium ions therefore corresponds to a good approximation of the total water hardness.
- the other alkaline earth metals, such as strontium and barium, are generally only present in water as trace substances and therefore hardly contribute to water hardness.
- Carbonate hardness can be removed by removing calcium and magnesium carbonate from the water.
- the dissolved hardness builders calcium and magnesium can form poorly soluble compounds in water, especially as carbonates with the carbon dioxide dissolved in the water.
- the calcium and magnesium ions are partially or completely removed from the water, for example in softening systems or in systems for complete desalination, for example by means of Cation exchangers are replaced by sodium ions or - in the case of full demineralization - are completely removed from the water together with all other dissolved ions, for example by a combination of cation and anion exchangers or by reverse osmosis.
- Water treatment plants are therefore known from the prior art in which, in order to produce partially softened or partially desalinated water with a predetermined water hardness, a raw water stream supplied is divided into two partial streams and a first partial stream is completely softened or fully desalinated and the completely softened or fully desalinated first partial stream with a second partial stream of raw water, which remains untreated, is mixed to produce a blended water stream.
- the hardness of the waste water produced can be adjusted to a predeterminable hardness target value via the mixing ratio of the first and second partial streams.
- blending devices are used in which the two partial streams can be mixed with an adjustable mixing ratio using controllable valves.
- complexometric titration methods can be used, for example with the disodium salt of ethylenediaminetetraacetic acid (EDTA) as a titrant, which can record the concentrations of alkaline earth ions dissolved in the water and thus the overall hardness of the water.
- EDTA ethylenediaminetetraacetic acid
- Measuring devices are known for this that photometrically record the color change point of the titration. These measuring devices are characterized by good measuring accuracy, but are complex and expensive to manufacture require regular maintenance and can hardly be used in automated measuring processes due to the use of the titrant.
- the total hardness of water can be determined using ion-selective electrodes (ISE), which record the ion activity of the calcium and magnesium ions.
- ISE ion-selective electrodes
- Ion-selective sensors require regular calibration with a calibration liquid, which makes their use in automated and low-maintenance measurement processes difficult.
- the water hardness can be determined from the electrical conductivity of the water.
- this method is very unspecific, especially if the water has a high proportion of non-carbonate hardness, for example due to a high content of Chlorides.
- connection between the electrical conductivity and the overall hardness of the water is very weak and must be recorded using characteristic curves by determining the connection between the titrimetrically determined hardness of different water samples and their electrical conductivity.
- the electrical conductivity of water is highly dependent on temperature, which is why the temperature must be recorded in addition to the conductivity and the hardness determination must receive a temperature correction using the characteristic curve. Therefore, conductivity measurements, which record the absolute conductivity of a water sample, are only partially suitable for determining the overall hardness of a water sample.
- a water softening system and a method for its operation are known, wherein the conductivity of the raw water is measured using a conductivity sensor and a total hardness of the raw water is determined from the measured conductivity, which is used to control a blending device.
- the total hardness of the raw water is derived from the measured conductivity using a calibration characteristic curve and the blending device is controlled in feedback based on the derived total hardness of the raw water so that a blended water hardness results that corresponds to a predetermined target hardness.
- the ones from the The water hardness determined by the calibration characteristic corresponds to a good approximation of an average water hardness, which occurs in a large number of drinking water analyzes with the measured conductivity.
- the titrimetrically determined water hardness that actually exists at a certain conductivity can deviate significantly from this average value, especially if the raw water has a relatively high non-carbonate hardness (permanent hardness). If the water hardness of the raw water determined from the calibration curve deviates, the actual hardness of the blended water does not correspond to the specified target hardness.
- a public drinking water supply provides a limited number of different drinking water qualities from different sources and with different compositions and hardness, whereby the introduction of these different drinking water qualities into the public drinking water supply network can change within a day or even within longer periods of time, so that The composition and hardness of the raw water supplied to a water treatment plant can change according to the quality of the drinking water provided by the public drinking water supply.
- Such changes in water quality which can occur several times during a day, change the overall hardness of the blended water produced in a blending device of a water treatment plant, with the result that its hardness no longer corresponds to the desired hardness.
- any changes in the composition or quality of the raw water must be recorded quickly during the operation of a water treatment plant.
- the invention is based on the object of demonstrating a method for operating a water treatment system and a water treatment system with a blending device which enables the total hardness of the raw water and/or the blended water to be recorded as precisely as possible without the use of chemicals and with low installation and operating costs and is low-maintenance, long-term stable and requires no calibration.
- the accuracy of the determination of the total hardness of the raw water and/or the blended water should in particular meet the requirements of the standard DIN 19636-100 “Softening systems (cation exchangers) in drinking water installations” for the accuracy of the blending.
- the procedure should in particular ensure that the blending device is calibrated as precisely as possible when the water treatment system is first put into operation and that changes in the hardness of the raw water supplied are recorded in situ during operation of the water treatment system in order to enable continuous control of the blending device, which is intended to produce blended water with a total hardness, which corresponds as closely as possible to a specified target hardness, regardless of the hardness of the raw water supplied and even if the quality of the raw water or the raw water hardness changes.
- a water treatment system which comprises a raw water inlet for providing raw water, a softening device, a blending device, a control device and at least one conductometric measuring device for the conductometric determination of the total hardness of the water in a water sample
- water softened from the raw water is produced in the softening device generated and in the blending device a blending water is first produced by mixing raw water from the raw water inlet with softened water from the softening device in an initial mixing ratio and fed to the measuring device and the measuring device carries out a conductometric measurement, in particular before and after an electrolytic precipitation of the alkaline earth ions Measurement and forwards the measurement results to the control device, which determines the total hardness of the blended water from the measurement results.
- the conductometric determination of the total hardness of the blended water enables a direct comparison of the determined total hardness of the blended water with a predeterminable target value of the water hardness of the blended water as well as a readjustment of the initial mixing ratio if a deviation results, in particular if a deviation lies above a predetermined limit value.
- the conductometric measurement carried out in the measuring device before and after electrolytic precipitation of the alkaline earth ions enables an exact determination of the total hardness of the blend water, since the electrolytic precipitation removes all hardness-forming alkaline earth ions, in particular as Carbonates are precipitated from the water and the change in the conductivity of the blended water caused by the precipitation of the alkaline earth ions is recorded using a conductometric difference measurement and the amount of alkaline earth ions precipitated and thus the total hardness of the blended water is determined very precisely using a conversion factor or a characteristic curve can be.
- the total hardness of the water in the water sample can be determined because the difference the conductivity of the water sample before and after the precipitation of the alkaline earth ions enables a determination of the total concentration of the alkaline earth ions in the water, the total concentration of which defines the total hardness of the water.
- the carbonate hardness corresponds to the total hardness of the blend water during the electrolysis of the water sample in the electrolysis cell.
- the change in conductivity caused by the at least essentially complete precipitation of the alkaline earth ions therefore represents a measure of the concentration of the hardness-forming alkaline earth ions in the blend water.
- the recorded change in conductivity (ALf) can be calculated using a predetermined conversion factor (F ), which is based in particular on a specific hardness scale, or by means of a predetermined characteristic curve which characterizes the course of the change in conductivity as a function of the change in hardness of the water when the carbonate hardness is precipitated, the total hardness of the blended water can be concluded.
- F predetermined conversion factor
- the measurement of the original electrical conductivity (Lfi) of the water sample of the blend water and the electrical conductivity (Lfi) of the water sample after the at least largely complete Precipitation of the alkaline earth ions can be done using an inexpensive conductivity sensor.
- the condition that there is an excess of hydrogen carbonate ions compared to the alkaline earth ions in the water of the water sample is usually automatically fulfilled in the case of blended water, which is obtained by mixing raw water with softened water, which is obtained by softening the raw water , because the concentration of hydrogen carbonate is retained in the blended water and, compared to the raw water, the hydrogen carbonate ions are present in excess of the alkaline earth metal ions. It has been shown that in blended water there is an excess of hydrogen carbonate ions compared to alkaline earth ions if the total hardness of the blended water is less than 3°dH.
- Empirical measurements on a large number of drinking water samples from Germany have shown that in blended water with a titrimetrically recorded total hardness of 5°dH or less, more than 98% of the drinking water samples have an excess of hydrogen carbonate ions compared to the alkaline earth ions. If the blend water does not already have an excess of hydrogen carbonate ions compared to the alkaline earth metal ions (which can be the case in particular if the total hardness GHv ⁇ 5°dH), hydrogen carbonate can be added to the blend water to ensure compliance with the measurement conditions in order to create an excess of the hydrogen carbonate ions compared to the alkaline earth ions.
- the control device is expediently set up in such a way that it also determines the total hardness of the raw water from the determined total hardness of the blended water, taking into account the initial mixing ratio or a mixing ratio that is readjusted during later operation of the water treatment system.
- the total hardness of the raw water determined in this way can be used, for example, to predict a remaining capacity of the ion exchanger and to determine a suitable time for initiating a regeneration process to regenerate the softening device, in particular one or more ion exchangers with a regeneration solution, for example a saline solution, when the water is exhausted Softening device can be used.
- the conductometric determination of the total hardness of the blended water can be carried out both when the water treatment system is started up and after a change in the quality and in particular the hardness of the raw water supplied.
- a change in the overall hardness of the raw water can occur during operation
- Water treatment system is continuously recorded by detecting the conductivity of the raw water by means of a conductivity sensor arranged in the raw water inlet or by means of the measuring device and any changes in the hardness of the raw water supplied are recognized from the recorded conductivity of the raw water.
- the hardness of the raw water can first be roughly estimated from the conductivity of the raw water, which is measured with the conductivity sensor arranged in the raw water inlet or by means of the measuring device, using a characteristic curve or a conversion factor in order to be based on the estimated hardness of the Raw water adjust the initial mixing ratio so that the total hardness of the blended water corresponds at least approximately to a predetermined target hardness of the blended water.
- the conductivity of the raw water is monitored either by means of the conductivity sensor arranged in the raw water inlet or by means of the measuring device in order to be able to determine changes in the hardness of the raw water supplied.
- the conductivity of water only correlates to a limited extent with the overall hardness of the water and at best a rough estimate of the water hardness can be made from the absolute conductivity of water using characteristic curves, a difference measurement that records a change in the electrical conductivity of the water is very suitable good for detecting changes in water hardness.
- the raw water is in a preferred embodiment bypassing the softening device Bypass line supplied.
- an additional conductivity sensor arranged in the raw water inlet can be dispensed with.
- the control device is coupled to the blending device and the initial mixing ratio is determined, in particular when the water treatment system is started up, by the control device according to the conductometric determination of the total hardness of the blended water depending on the recorded total hardness of the blended water (new) mixing ratio is set in which the total hardness of the blended water corresponds to the specified target hardness.
- the measured values of the conductivity of the raw water recorded during operation of the water treatment system are advantageously stored in a data memory of the control device together with the determined total hardness of the blended water and/or the associated mixing ratio of the blended water. This enables the control device to adapt the mixing ratio and the regeneration trigger to the changed water quality in the event of a change in the water quality or the hardness of the raw water supplied and a determination of the changed water quality due to a change in the measured conductivity of the raw water, without having to re-determine the total hardness of the blended water and/or the raw water using the measuring device.
- all drinking water qualities available at the site of use of the water treatment system and their total hardness or their conductivity have been recorded and the recorded measured values of the conductivity and the mixing ratios with softened or desalinated water and the total hardness of the blended water resulting from the corresponding mixing ratio are stored in the memory of the control device, so that if a change in the conductivity of the raw water is detected, it draws conclusions about the changed water quality of the raw water supplied and, using the stored data, adapts the mixing ratio and the regeneration trigger to the changed water quality of the raw water and in particular its hardness can.
- the total hardness of the blend water is preferably determined conductometrically after electrolytic precipitation of the alkaline earth metal ions, in particular the calcium and/or magnesium ions.
- an electrolytic precipitation of the alkaline earth metal ions is carried out in the waste water supplied to the measuring device, the measuring device preferably determining the electrical conductivity of the waste water before precipitation (Lfi) and the electrical conductivity of the waste water after precipitation (Lf2).
- the amount of change in conductivity (ALf
- ) caused by the electrolytic precipitation of the alkaline earth ions in the blended water can be determined and from this The total hardness of the blended water can be determined using a conversion factor or a calibration curve.
- this change in conductivity is detected with the measuring device, the amount of the detected change in conductivity (ALf) representing a measure of the concentration of the hardness-forming alkaline earth ions in the blend water and therefore from the detected change in conductivity ( ALf) the total hardness of the blend water can be deduced by means of a predetermined conversion factor or a predetermined characteristic curve of the course of the conductivity of water depending on the total hardness of the water and from the set blend the total hardness of the raw water.
- the measurement of the original electrical conductivity (Lfi) of the water sample and the electrical conductivity (Lf 2 ) of the water sample after the at least largely complete precipitation of the alkaline earth ions can be carried out with a cost-effective conductivity sensor, which is preferably integrated in the electrolysis cell of the measuring device or else can be arranged outside the electrolysis cell.
- the electrolysis of the water sample in the electrolysis cell of the measuring device takes place only for the purpose of precipitating the alkaline earth metal ions.
- the further effects of the electrolysis of the water sample, in particular the decomposition of the water into hydrogen and oxygen, are not exploited.
- the total hardness of the water sample of the blended water is determined from the recorded change in the conductivity (ALf) of the water sample using a conversion factor (F), which is in particular a proportionality factor of a linear relationship between the conductivity of water and the carbonate hardness of the water.
- the conversion factor can be taken from a characteristic curve which, when the carbonate hardness of a water sample precipitates, describes a linear course of the change in electrical conductivity depending on the change in the total hardness or the carbonate hardness of the water.
- the conversion factor (F) results from the ratio between the mass of hardness formers that are removed during the electrolysis of the water by precipitation of the alkaline earth metal ions (as carbonates) and the resulting reduction in the electrical conductivity of the water sample due to the precipitation the alkaline earth ions reduced ion concentration in the water.
- the reduction in the electrical conductivity of the water sample is linear to the precipitated concentration of alkaline earth ions, with the conversion factor (F) being the proportionality constant of this linear progression.
- the conversion factor (F) or the characteristic curve can be determined experimentally and in particular empirically on a large number of different water samples, in particular on different drinking water samples of different origins or compositions with an excess of hydrogen carbonate ions compared to the alkaline earth ions, by using a Conductometric titration determines the relationship between the titrimetrically determined total hardness and the change in electrical conductivity due to complete precipitation of the alkaline earth ions and from this a course of the change in conductivity depending on the total hardness of the water is determined in a diagram or a characteristic curve.
- a common hardness scale in particular the German water hardness or the French water hardness, can be used as a measure of the overall hardness.
- the overall hardness is determined titrimetrically when determining the conversion factor or the characteristic curve, for example by EDTA titration (according to DIN 38406-3, Group E-Part 3).
- the conversion factor (F) or the characteristic curve can also be determined experimentally on water samples with a sufficient concentration of alkaline earth ions without a predetermined excess of hydrogen carbonate ions (i.e. in particular without preconditioning the water sample) by performing electrolytic precipitation on the water samples Carbonate is carried out and both the change in electrical conductivity caused by the precipitation and the change in hardness (total hardness or carbonate hardness) of the water sample are recorded in a diagram in a titrimetric manner and the connection between the change in conductivity and the change in hardness is determined from this.
- the conversion factor F results as a proportionality factor from the generally linear course of the change in conductivity depending on the change in hardness.
- the recorded change in conductivity represents a measure of the overall hardness of the blended water, which can be traced back to a common hardness scale via the conversion factor or the characteristic curve and can therefore be expressed as the total hardness of the blended water.
- a conclusion is drawn from the precipitated (temporary) hardness to the (original) total hardness of the water sample of the blended water using mass balance calculations.
- the conductivity of the water sample of the blend water during the electrolytic precipitation of the alkaline earth ions is preferably recorded up to a transition point, in which the recorded conductivity has a minimum value (Lf2) due to complete precipitation of the alkaline earth ions. If the water sample is electrolyzed further beyond the transition point, a sudden or gradual increase in the recorded conductivity of the water sample can be observed.
- the Conductivity of the water sample of the blend water during the electrolytic precipitation of the alkaline earth ions is preferably recorded at least until at least 90% of the alkaline earth ions, particularly preferably more than 95%, have been precipitated by the electrolysis.
- the water sample of the blend water is preferably introduced into an electrolysis cell in which at least two electrolysis electrodes are arranged and which are subjected to direct voltage for the electrolytic precipitation of the alkaline earth ions.
- the electrolysis electrodes can, for example, be designed as conductive plates (flat electrodes) arranged at a distance and parallel to one another.
- the water sample can be introduced in a batch operation between the two electrolysis electrodes and the electrolysis cell is then closed to carry out the measurement.
- a certain volume of a water sample of the blend water which expediently corresponds to the internal volume of the electrolytic cell, is introduced into the electrolytic cell in batch operation (batch operation).
- the original conductivity Lfi of the water sample is recorded in a first measurement cycle.
- the electrolytic precipitation of the alkaline earth ions can then begin by applying a direct voltage to the electrolysis electrodes during a first electrolysis cycle.
- the conductivity sensor which is preferably integrated into the electrolysis cell, is switched off during the first electrolysis cycle, ie the measuring electrodes are not subjected to alternating voltage during the electrolytic precipitation of the alkaline earth metal ions.
- the first electrolysis cycle can then be alternately followed by further measuring cycles and further electrolysis cycles in order to precipitate the alkaline earth metal ions contained in the waste water and to record the course of the conductivity of the water sample of the waste water selectively or quasi-continuously during the precipitation until the alkaline earth metal ions at least have essentially completely failed.
- the electrolysis electrodes are switched off and the conductivity Lf2 of the water sample is recorded in a final measuring cycle and the difference is determined by forming the difference between the original conductivity Lfi and the conductivity Lf2 measured in the last measuring cycle, which is determined by the precipitation of the alkaline earth ions.
- Ion-induced change in conductivity ALf
- the duration of the electrolysis cycles is preferably between 2 minutes and 10 Minutes and is, for example, 5 minutes and the duration of the measuring cycles is expediently between 30 seconds and 120 seconds and is, for example, 60 seconds.
- the electrolysis cell expediently contains at least one integrated conductivity sensor.
- the conductivity sensor integrated into the electrolysis cell preferably comprises two measuring electrodes, to which an alternating voltage is applied to record the conductivity of the water sample and the current intensity of the current passed through the measuring electrodes is measured.
- an electrolytic precipitation of the alkaline earth ions and a measurement of the conductivity of the water sample take place alternately in the measuring mode in the electrolysis cell. This decouples the electrolytic precipitation of the alkaline earth ions and the measurement of the conductivity with the at least one conductivity sensor integrated into the electrolysis cell, thereby avoiding interference when measuring the conductivity.
- the temperature of the water sample is preferably measured in the measuring mode and in particular during the electrolytic precipitation of the alkaline earth ions and in the mathematical determination of the total hardness of the blend water from the recorded change in conductivity ( ALf) a temperature correction is preferably carried out via a temperature correction factor or a temperature characteristic curve, which represents the dependence of the conductivity of water on the temperature.
- the water treatment system comprises a raw water inlet for providing raw water, a softening device connected to the raw water inlet, which in particular contains at least one ion exchanger or can also be designed as a desalination device, a blending device for producing blended water by mixing raw water from the raw water inlet with softened or desalinated raw water from the softening device in a predeterminable mixing ratio, a control device and at least one conductometric measuring device, the control device being set up to determine the hardness of the water in a water sample supplied to the conductometric measuring device and the Measuring device is connected to the blending device in order to supply the measuring device with blending water from the blending device and to determine the total hardness of the blending water, the control device controlling the measuring device in such a way that it carries out a conductometric measurement in particular before and after an electrolytic precipitation of the alkaline earth ions and forwards the measurement result to the control device in order to determine the total hardness of the blended water from the measurement result
- the control device is expediently set up in such a way that it also determines the hardness of the raw water from the determined total hardness of the blended water, taking the mixing ratio into account. Based on the determined raw water hardness, an estimate of the softening capacity of the softening device can be made and/or if the softening capacity is predicted to be exhausted soon, a regeneration process can be initiated to regenerate the softening device, in particular the ion exchanger, using a regeneration solution.
- the measuring device comprises an electrolysis cell with at least two electrolysis electrodes and at least one conductivity sensor, the conductivity sensor preferably being integrated into the electrolysis cell.
- the electrolysis cell and/or the conductivity sensor expediently comprises a temperature sensor for detecting the temperature of the water sample during a measuring mode.
- the electrolysis electrodes which are connected to a direct current source for the electrolytic precipitation of the alkaline earth ions, are preferably arranged opposite one another in the electrolysis cell of the measuring device and are expediently designed as flat electrodes. This allows a sufficient volume of the electrolytic cell to be accommodated a water sample of the blended water can be provided with a compact design of the measuring device.
- the electrolysis electrodes include at least one anode, which is preferably made of platinized titanium sheet or a platinized titanium grid or a graphite film, and at least one cathode, which is preferably made of steel or titanium.
- the measuring device comprises at least one conductivity sensor.
- At least one conductivity sensor is preferably integrated in the electrolytic cell of the measuring device, this conductivity sensor comprising at least one pair of electrodes with two measuring electrodes which are connected or can be connected to an alternating voltage source.
- the integration of one or more conductivity sensors into the electrolytic cell enables a compact and space-saving design of the measuring device.
- at least a first conductivity sensor and/or a second conductivity sensor to be arranged outside the electrolytic cell.
- a first conductivity sensor can be placed upstream of the entrance of the electrolysis cell and a second conductivity sensor downstream of the exit of the electrolysis cell.
- the conductivity sensor of the measuring device preferably comprises at least one pair of electrodes with two measuring electrodes, in particular designed as rod electrodes, which are connected to an alternating voltage source.
- the measuring electrodes are expediently arranged between the opposite electrolysis electrodes of the electrolysis cell.
- a further conductivity sensor is preferably arranged in the raw water inlet of the water treatment system according to the invention.
- the control device of the water treatment system is preferably coupled to the blending device and set up in such a way that the mixing ratio is regulated to a predetermined target value of the total hardness of the waste water depending on the specific total hardness of the waste water, the control device preferably constantly or at certain times, the conductivity of the raw water detected by means of the measuring device or by means of the additional conductivity sensor in the raw water inlet is supplied and the control device, depending on the detected conductivity of the raw water, in particular in the event of a detected change in the conductivity of the raw water, conductometrically determines the total hardness of the raw water Blended water is initiated using the measuring device.
- the control device of the water treatment system expediently contains a data memory in which a conversion factor or a characteristic curve which shows the course of the change in the conductivity of water when the carbonate hardness is precipitated as a function of the change in the hardness of the water is stored.
- the control device accesses the conversion factor or the characteristic curve and is preferably set up so that it calculates the total hardness of the blended water on a hardness scale assigned to the conversion factor or the characteristic curve from the detected change in conductivity (ALf) and the conversion factor or the characteristic curve.
- a cation exchange membrane can be arranged between the two opposite electrolysis electrodes of the electrolysis cell, the cation exchange membrane running in particular parallel to the electrolysis electrodes designed as flat electrodes.
- several pairs of electrolysis electrodes can also be arranged at a distance from one another in the electrolysis cell of the measuring device, in particular in the form of flat electrodes which run parallel to one another.
- a cascade arrangement of corresponding electrolysis electrodes in the order anode - cathode - anode - cathode - anode can be provided in the electrolysis cell. This also accelerates the precipitation of alkaline earth ions in the measuring cycles and therefore reduces the measuring time.
- the total hardness of the blend water which is determined by the carbonate hardness (temporary hardness), as well as the total hardness of the raw water can be determined with sufficient accuracy in an automated process without the use of chemicals.
- the mixing ratio or the volume fraction of the raw water in the blended water can be as follows can be set so that the total hardness of the blended water corresponds to a specified target hardness.
- the method and the water treatment system also enable in-situ detection of a change in the conductivity of the raw water supplied in order to be able to quickly adjust the mixing ratio if the water quality of the raw water supplied changes so that the hardness of the blended water corresponds to the specified target hardness and the Regeneration triggering and the capacity can be recalculated.
- Fig. 1 a schematic representation of an exemplary embodiment of a water treatment system according to the invention
- Fig. 2 schematic representations of various embodiments of a conductometric measuring device that can be used in the water treatment system according to the invention and the method according to the invention;
- Fig- 3 a flow chart of a preferred embodiment of the invention
- Fig. 5 a diagram of the time course of the electrical conductivity of a water sample with waste water from the water treatment plant of Figure 1, recorded in the method according to the invention, as well as the time course of the hardness of the waste water determined using the method according to the invention.
- 1 shows an exemplary embodiment of the water treatment system according to the invention, wherein the water treatment system 10 has a raw water inlet 11 for providing raw water R, a softening device 12 connected to the raw water inlet 11, which contains at least one ion exchanger 13, a control head 24, a blending valve vl for generating Blended water V, a control device 14 and at least one conductometric measuring device 15.
- the control head 24 is connected to the raw water inlet 11 and to the softening device 12 and is set up to control the volume flows of the raw water R to the softening device 12 and the water W softened in the softening device 12 in a waste water line 20 connected to the control head 24 and is controlled for this by the control device 14.
- the measuring device 15 is arranged downstream of the blending device 24, vl.
- the ion exchanger 13 of the softening device 12 is contained in an ion exchange container 8 which has an inlet 11a and an outlet 11b.
- the water treatment system 10 further comprises a regeneration device 18, which has a regeneration container 9 in which an aqueous regeneration solution, in particular a sodium chloride solution, is stored.
- the regeneration solution is passed through the ion exchange container 8 in a regeneration mode, whereby the calcium and magnesium ions bound in the ion exchanger 13 when softening the raw water R are replaced by sodium ions.
- the used regeneration solution is passed into a channel 19 via a discharge line 23.
- the input 11a of the softening device 12 is connected via the control head 24 to the raw water inlet 11, via which (hard) raw water R is supplied to the softening device 12 for softening.
- a conductivity sensor 16 is arranged in the raw water inlet 11.
- the output 11b of the softening device 12 is connected to the control head 24 via an outlet line 7 in order to direct the water (soft water W) softened by ion exchange in the ion exchanger 13 into the waste water line 20.
- the softened water W is mixed with raw water R in a defined mixing ratio, which depends on the position of the blending valve vl, in order to produce a blending water V.
- the hardness of the blended water V depends on the hardness of the raw water R and the mixing ratio of the softened water W with the raw water R.
- the waste water V generated in the blending device 24, vl is discharged via the waste water line 20 and directed to a consumer 22 via a consumer line 21 connected to the waste water line 20.
- the consumer 22 can be, for example, the drinking water installation of a household or a water device to which the waste water V is supplied directly.
- the control device 14 is coupled to the blending device 24, vl in order to achieve this by adjusting the adjustable blending valve vl the blending device 24, vl to be able to adjust the mixing ratio appropriately.
- the control device 14 is coupled to the conductivity sensor 16 arranged in the raw water inlet 11 and receives the measured value of the electrical conductivity of the raw water R recorded by this sensor.
- the control device 14 Based on the measured value of the conductivity of the raw water R (conductivity LR), the control device 14 estimates the hardness of the raw water by relying on a characteristic curve stored in a data memory, which describes the course of the electrical conductivity of water depending on the water hardness, and calculates it from this initial mixing ratio r:w_0, which is determined so that the predicted hardness of the blended water at least approximately corresponds to the target hardness.
- the exact total hardness GHv of the blended water V is determined using the measuring device 15. This is what this is for Waste water V is passed via the waste water line 20 through a valve V2 that can be controlled by the control device to an inlet 15a of the measuring device 15 and flushed through it.
- the measuring device 15 comprises an electrolysis cell 1, which has a container 5 in which the input 15a and an output 15b are provided.
- a water sample whose hardness is to be determined can be introduced into the container 5 of the measuring device 15 via the input 15a.
- the entrance 15a and the exit 15b of the container 5 are closed. After completing a measurement, the water sample can be drained into a channel 19 by opening the exit 15b.
- the measuring device 15 shown in Figure 2A comprises an electrolytic cell 1 with a container 5, which contains an outlet at the entrance 15a via an access (not shown here) for introducing the water sample and at the exit 15b an outlet for draining the water sample after the hardness determination has been carried out.
- the access and the outlet can be closed so that the water is in a closed volume after the water sample has been introduced into the container 5.
- Two flat electrodes running parallel to one another and spaced apart are arranged within the container 5.
- the two flat electrodes form mutually assigned electrolysis electrodes A, K, one flat electrode being provided as an anode (A) and the other flat electrode being provided as a cathode (K).
- the two electrolysis electrodes A, K are connected to a direct current source DC, as indicated in Figure 2A.
- the two electrolysis electrodes A, K are supplied with direct electrical current via the direct current source DC.
- a conductivity sensor 2 with two measuring electrodes, which form a pair of electrodes 3, is arranged between the two electrolysis electrodes A, K.
- the pair of electrodes 3 is connected to an alternating voltage source AC and can be supplied with an alternating electrical voltage of a predetermined value via the alternating voltage source AC frequency are applied.
- the electrode pair 3 acts as a conductivity sensor 2, with which the conductivity of the water in the container 5 can be detected by measuring the current strength of the current passed through the measuring electrodes of the electrode pair 3.
- the two measuring electrodes are designed as rod electrodes, the longitudinal axis of which runs parallel to the plane of the two electrolysis electrodes A, K designed as flat electrodes.
- the measuring device 15 with the electrolysis cell 1 and the two electrolysis electrodes A, K arranged therein and the conductivity sensor 2 integrated in the electrolysis cell 1 is coupled to the control device 14.
- the control device 14 controls the supply of the electrolysis electrodes A, K with direct electrical current during predetermined electrolysis cycles. Furthermore, the detection of the electrical conductivity of the water sample located in the container 5 by means of the conductivity sensor 2 is controlled by the control device 14 by applying an alternating electrical voltage to the pair of electrodes 3 of the conductivity sensor 2 in defined measuring cycles.
- control device 14 is preferably set up in such a way that measurement cycles with a predetermined measurement duration and electrolysis cycles with a predetermined electrolysis duration are carried out alternately one after the other, with the pair of electrodes 3 of the conductivity sensor 2 preferably being subjected to alternating voltage during a measurement cycle, while the two electrolysis electrodes A, K are de-energized and during an electrolysis cycle the two electrolysis electrodes A, K are supplied with direct electrical current, while the pair of electrodes 3 is voltage-free.
- the control device 14 includes a data memory and a computing unit. At least one characteristic curve is stored in the data memory, which represents the course of the electrical conductivity of water depending on the total hardness of the water on a hardness scale.
- the data memory of the control device 14 can also contain several such characteristics, with the individual characteristics, for example, the course of the electrical conductivity of water depending on the hardness of the water on different hardness scales, for example the German hardness scale (°dH) or the French hardness (° fH). If the characteristic curve has a linear course of the electrical conductivity depending on the hardness of the water, the proportionality factor, which indicates the slope of this linear curve, can also be stored as a conversion factor F in addition to or instead of the characteristic curve in the memory of the control device 14.
- the original conductivity Lfi is first determined in a measuring mode with the electrolysis electrodes A, K switched off without current using the conductivity sensor 2 by applying an alternating electrical voltage to the pair of electrodes 3 at a predetermined frequency of the water measured. This measurement represents a first measurement cycle. The voltage on the electrode pair 3 of the conductivity sensor 2 is then switched off and a first electrolysis cycle begins for a predetermined electrolysis period. For this purpose, a direct voltage is applied to the two electrolysis electrodes A, K.
- the water in the container 5 is electrolyzed and at the same time the alkaline earth metal ions in the water begin to precipitate as carbonates, in particular as calcium carbonate and as magnesium carbonate, and at the cathode ( K) to invest.
- the power supply to the electrolysis electrodes A, K is switched off and a two measuring cycle is carried out by applying an alternating voltage to the pair of electrodes 3 of the conductivity sensor 2 during a predetermined measuring period. The electrical conductivity of the water in the container 5 is recorded.
- the conductivity which is measured in the second measurement cycle, has decreased compared to the original conductivity of the water, since the precipitated alkaline earth ions no longer contribute to the current flow in the electrolytic cell 1. Further electrolysis cycles and measurement cycles are then carried out alternately one after the other.
- the resulting time course of the electrical conductivity of the water in the container 5 is shown using an example in Figure 4.
- the individual measurement cycles M can be seen in which the conductivity of the water does not change.
- the electrolysis cycles E are located between successive measurement cycles M with constant conductivity, with the electrical conductivity of the water continuing to decrease in each electrolysis cycle E due to the progressive filling of the alkaline earth metal ions, up to a transition point marked U in Figure 4, at which the conductivity of the water detected by the conductivity sensor 2 increases suddenly or gradually.
- the (possibly sudden) increase in electrical conductivity at the transition point U probably results from a sudden increase in the pH value and a resulting excess of anions (CCL 2 ' and OH') with higher equivalent conductivity compared to the hydrogen carbonate ions after completion of cathodic precipitation.
- the conductivity of the water detected by the conductivity sensor 2 has a minimum value Lf2.
- H ALf/ F
- H the hardness of the water
- ALf the difference in the measured conductivities of the water before and after the complete precipitation of the alkaline earth ions
- F the conversion factor that results from the characteristic curve of the (linear) course of the change in conductivity Water in the event of precipitation of the carbonate hardness of the water as a function of the change in hardness, in particular the change in the overall hardness of the water, and in particular is the proportionality factor of a linear course of this characteristic curve.
- the (empirically determined) factor F results from the ratio between the mass of hardness formers removed by precipitation and the reduction in conductivity thanks to proportionally reduced ion concentrations.
- the curve of an electrolytic hardness precipitation runs almost linearly, as shown in Figure 4 visible.
- the conductivity progression over time is no longer linear, but the transition point U remains unchanged at the same conductivity value (conductance).
- the transition point U corresponds quite precisely to the existing total concentrations of alkaline earth ions because of the comparable equivalent conductances of Ca and Mg. From empirical measurements on a large number of drinking water samples from Germany of different origins and different compositions, the conversion factor F at a temperature of 15°C results in a value of, for example
- FIG. 2A and 2B show two further embodiments of a measuring device 15 with an electrolytic cell 1, the electrolytic cell 1 containing two separate conductivity sensors 2a, 2b.
- a first conductivity sensor 2a is arranged at the closable entrance 15a of the electrolytic cell 1 and a second conductivity sensor 2b at the closable output 15b of the electrolytic cell 1.
- Each conductivity sensor 2a, 2b comprises a pair of electrodes 3a, 3b, each with a first measuring electrode a (measuring anode) and a second measuring electrode k (measuring cathode).
- the two electrolysis electrodes A, K are arranged between the input 15a and the output 15b of the electrolysis cell 1, which, as in the exemplary embodiment of FIG. 2A, are designed as flat electrodes and are arranged opposite one another at a predetermined distance.
- the embodiment of the electrolysis cell 1 shown in FIG. 2B can be used to record the electrical conductivity of a water sample which flows continuously from the entrance 15a to the exit 15b through the electrolysis cell 1 in flow mode. While the water sample flows through the electrolytic cell 1, the conductivity Lf a of the water flow at the inlet 15a and the conductivity Lfi at the outlet 15b are measured continuously with the two conductivity sensors 2a, 2b.
- the measuring device 15 In order to determine the total hardness of the water of the water flow supplied to the measuring device 15, the measuring device 15 according to the second embodiment of FIG getting closed. The hardness of the water in the container 5 of the measuring device 15 is then determined using the measuring mode described with reference to the embodiment in FIG. 2A.
- the electrolysis cell 1 of the exemplary embodiment of FIG. 2C contains a cascade of electrolysis electrodes in the sequence of an outer anode A, a first cathode K, an inner anode A, a second cathode K and a further outer anode A, as can be seen from FIG. 2C.
- a cation exchange membrane KAT is arranged between corresponding electrolysis electrodes A, K.
- a target hardness GHv so11 is specified to the control device 14 via a communication interface, which is in particular between 2°dH and 15°dH and preferably between 3°dH and 10°dH and particularly preferably between 3°dH and 6°dH (step Sl).
- a communication interface which is in particular between 2°dH and 15°dH and preferably between 3°dH and 10°dH and particularly preferably between 3°dH and 6°dH.
- the control device 14 roughly estimates the hardness HR of the raw water based on the measured conductivity of the raw water LfR by accessing a characteristic curve stored in the data memory and positions the blending valve vl of the blending device 24, vl so that an initial mixing ratio r:w_0 results, in which the expected total hardness GHv of the blend water V has a low value, which is preferably ⁇ 3°dH (step S3).
- the blended water V produced with this setting of the blending valve vl has an excess of hydrogen carbonate ions compared to the alkaline earth ions, which enables an accurate measurement of the total hardness GHv of the blended water using the measuring method described above. Many thousands of drinking water analyzes have shown that with this setting the hydrogen carbonate content is in excess of the alkaline earths.
- a water sample of the waste water V produced is fed to the container 5 of the measuring device 15 and the container 5 is closed so that the water sample of the waste water V with a certain volume is contained therein (step S4).
- the blending valve vl is then prepositioned to a preliminary mixing ratio r:w_l, at which, based on the raw water hardness roughly determined in step S2, the hardness of the blended water approximately corresponds to the target hardness (step S5).
- the water treatment system 10 is operated with this setting of the preliminary mixing ratio r:w_l until an accurate recording of the blended water hardness GHv and the raw water hardness HR is completed and based on these values Fine adjustment of the mixing ratio can be carried out in order to achieve the specified target hardness GHv so11 of the blended water as accurately as possible.
- step S5 a measuring mode is carried out in the measuring device 15, in which the total hardness GHv of the blend water V and from this the hardness of the raw water R is determined using the known initial mixing ratio r:w_0 (step S6). .
- step S6 the (original) electrical conductivity of the blend water V is measured in the electrolysis cell 1 of the measuring device 15 by means of the conductivity sensor 2 integrated into the electrolysis cell 1 and then the water sample of the blend water located in the container 5 of the electrolysis cell 1 is measured V is electrolyzed with the container 5 closed by means of the electrolysis electrodes A, K by applying an electrical direct voltage to the electrolysis electrodes A, K.
- the alkaline earth metal ions contained in the water sample of the blend water V are precipitated out of the water.
- the electrical conductivity of the waste water V located in the container 5 of the electrolytic cell 1 is measured with the integrated conductivity sensor 2 or the conductivity sensors 2a and 2b in order to detect the transition point U, which results in complete precipitation of the alkaline earth -Ions, as described above using the measuring devices of Figure 2.
- control device 14 is coupled to the conductivity sensor 2 in order to obtain the measured values of the conductivity measurement (conductance values) before, during and after the precipitation of the alkaline earth ions.
- the control device 14 calculates the exact total hardness GHv of the blend water V from the detected difference in the electrical conductivity ALf using the conversion factor F stored in a memory of the control device 14, as described above (step S7).
- the measurement time required for this until the alkaline earth ions have completely precipitated depends on the hardness of the water in the water sample and is approximately between 10 and 15 minutes/ 0 dH and is less than due to the low hardness of the blend water set via the initial mixing ratio r:w_0 45 minutes.
- the control device 14 Based on the total hardness GHv of the blended water V determined by the control device 14, the control device 14 adjusts the blending device 24, vl for this purpose, in order to adapt the preliminary mixing ratio r:w_l of the raw water with the softened water W to a new mixing ratio r:w_2 so that the blended water V has a total hardness GHv which corresponds to the specified target hardness GHv so11 (step S8).
- the control device 14 (in step S7) can also calculate the hardness HR of the raw water R from the determined total hardness GHv of the blend water V, taking into account the original mixing ratio.
- the hardness HR of the raw water R can, for example, be used to predict a softening capacity of the softening device 12 and to initiate a regeneration process with the regeneration device 18 in order to carry out regeneration in good time before the ion exchanger 13 is exhausted in order to avoid a hardness breakthrough.
- changes in the hardness HR of the raw water R which can occur, for example, when the water quality of the drinking water provided by the public drinking water supply changes, are recorded by the conductivity sensor 16 and taken into account when adjusting the blending valve vl Mixing ratio is adjusted to a changed hardness of the raw water R.
- the measured values of the conductivity LfR(n+l) of the raw water R currently recorded by the conductivity sensor 16 are sent to the control device 14, which compares the recorded measured values with the previous measured values LfR(n) (step S9).
- a further measuring mode is initiated in the manner described above with the measuring device 15 the total hardness GHv of the blended water V is determined and, depending on this, an adjustment of the mixing ratio of the blended water V is made if necessary.
- the limit value SLfR is expediently in the range from 30 to 40 pS/cm and is in particular 30 pS/cm.
- step S10 As long as no change in the conductivity LfR of the raw water R is detected during operation of the water treatment system, the amount of which is above the limit value SLfR, the setting of the blending valve vl of the blending device 24, vl remains unchanged (step S10).
- the conductivity values of the raw water LfR recorded by the conductivity sensor 16 are stored in a memory of the control device 14 together with the associated raw water hardness HR. If an already known raw water conductivity value is recognized again, then the analysis process is no longer started, but the raw water hardness HR already stored in the control memory and assigned to this conductance value is used as a new control variable for setting the mixing ratio in order to determine the target hardness GHv so11 of the blended water V to reach.
- FIG. 5 shows an example of the time course of a measurement of the electrical conductivity of the blend water V or the raw water R (measured conductance values Lfv or LfR) in the water treatment system of FIG. 1 with a changing hardness HR of the raw water R supplied via the raw water inlet 11 and the Time course of the hardness GHv of the blended water V determined from the conductivity of the blended water V and the hardness HR of the raw water R determined from this by calculation taking the mixing ratio into account.
- a measuring mode was carried out to determine the total hardness GHv of the blend water V and from this the hardness HR of the raw water R and to adjust the mixing ratio of raw water R with softened water W so that the total hardness GHv of the blend water V corresponds to the specified target hardness GHv so11 of 3°dH corresponds.
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Abstract
La présente invention concerne une installation de traitement des eaux et son procédé de fonctionnement. L'installation de traitement des eaux (10) présente une alimentation en eau brute (11) pour fournir de l'eau brute (R), un dispositif d'adoucissement (12) qui produit de l'eau adoucie (W) à partir de l'eau brute (R), et un dispositif de mélange (24, v1) pour mélanger de l'eau brute (R) à partir de l'alimentation en eau brute (11) avec de l'eau adoucie (W) à partir du dispositif d'adoucissement (12), le dispositif de mélange (24, v1) produisant de l'eau mélangée (V) par mélange d'eau brute (R) avec de l'eau adoucie (W) dans un rapport de mélange réglable. L'installation de traitement des eaux comprend en outre un dispositif de commande (14) et au moins un dispositif de mesure conductimétrique (15) qui est conçu pour effectuer une détermination conductimétrique de la dureté totale de l'eau d'un échantillon d'eau. Le but de l'invention est de permettre une détection, la plus précise possible, de la dureté totale de l'eau brute et/ou de l'eau mélangée sans utiliser de produits chimiques tout en ayant de faibles coûts d'installation et de fonctionnement et tout en nécessitant peu d'entretien et en ayant une stabilité à long terme sans nécessiter d'étalonnage. À cet effet, le dispositif de mesure (15) est alimenté en eau mélangée (V) à partir du dispositif de mélange (24, v1), et le dispositif de mesure (15) effectue une mesure conductométrique, en particulier avant et après une précipitation électrolytique d'ions alcalino-terreux, les résultats de mesure étant transmis au dispositif de commande (14) afin de déterminer la dureté totale (GHv) de l'eau mélangée (V).
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DE102022107575.3A DE102022107575A1 (de) | 2022-03-30 | 2022-03-30 | Wasserbehandlungsanlage und Verfahren zum Betrieb einer Wasserbehandlungsanlage |
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Citations (5)
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DE102007059058B3 (de) | 2007-12-06 | 2009-07-30 | Judo Wasseraufbereitung Gmbh | Verfahren zum Betrieb einer Wasserenthärtungsanlage mit zwei Kalibrierkennlinien und zugehörige Wasserenthärtungsanlage |
EP2528868B1 (fr) * | 2010-01-29 | 2014-04-16 | Judo Wasseraufbereitung GmbH | Procédé de fonctionnement d'une installation de traitement de l'eau comprenant une correction des courbes caractéristiques d'étalonnage |
EP2512994B1 (fr) * | 2009-12-18 | 2014-04-30 | Judo Wasseraufbereitung GmbH | Détermination de la dureté de l'eau non traitée dans une installation de traitement d'eau au moyen de la conductivité de l'eau douce ou de l'eau de dilution |
EP2552836B1 (fr) * | 2010-04-01 | 2017-11-15 | Judo Wasseraufbereitung GmbH | Procédé de surveillance d'une installation de traitement d'eau pour une installation de remplissage de circuit |
US20190352198A1 (en) * | 2017-02-07 | 2019-11-21 | Bwt Aktiengesellschaft | Water softening device and method of operating a water softening device |
Family Cites Families (2)
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CN102105405B (zh) | 2008-08-09 | 2015-10-14 | 居道水再生有限公司 | 用于软化装置的可改装式控制单元 |
DE102008045354B3 (de) | 2008-09-02 | 2010-02-25 | Judo Wasseraufbereitung Gmbh | Aussetzen von Messgrößenauswertungen in einer automatischen Wasserenthärtungsanlage bei Vorliegen von definierten Betriebssituationen |
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2022
- 2022-03-30 DE DE102022107575.3A patent/DE102022107575A1/de active Pending
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102007059058B3 (de) | 2007-12-06 | 2009-07-30 | Judo Wasseraufbereitung Gmbh | Verfahren zum Betrieb einer Wasserenthärtungsanlage mit zwei Kalibrierkennlinien und zugehörige Wasserenthärtungsanlage |
EP2512994B1 (fr) * | 2009-12-18 | 2014-04-30 | Judo Wasseraufbereitung GmbH | Détermination de la dureté de l'eau non traitée dans une installation de traitement d'eau au moyen de la conductivité de l'eau douce ou de l'eau de dilution |
EP2528868B1 (fr) * | 2010-01-29 | 2014-04-16 | Judo Wasseraufbereitung GmbH | Procédé de fonctionnement d'une installation de traitement de l'eau comprenant une correction des courbes caractéristiques d'étalonnage |
EP2552836B1 (fr) * | 2010-04-01 | 2017-11-15 | Judo Wasseraufbereitung GmbH | Procédé de surveillance d'une installation de traitement d'eau pour une installation de remplissage de circuit |
US20190352198A1 (en) * | 2017-02-07 | 2019-11-21 | Bwt Aktiengesellschaft | Water softening device and method of operating a water softening device |
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