Water hardness detection method and system

Abstract

The invention discloses a water quality hardness detection method and system. The method comprises the following steps: acquiring a first association relationship, a second association relationship and a third association relationship between a water quality total correction factor f (w) / eta and water pH, temperature and TDS; the method comprises the following steps: acquiring a first pH value, a first temperature and a first TDS of raw water, determining f (w) / eta corresponding to the first pH value as a reference correction parameter, and determining f (w) / eta corresponding to the first temperature and the first TDS as a first correction factor and a second correction factor; acquiring a second temperature and a second TDS of the water body, and determining f (w) / eta corresponding to the second temperature and the second TDS as a third correction factor and a fourth correction factor; determining a temperature gain according to the first correction factor and the third correction factor, and determining a TDS gain according to the second correction factor and the fourth correction factor; obtaining a raw water total correction factor according to the temperature gain and the TDS gain; and determining the hardness of the raw water according to the total correction factor of the raw water, the TDS value and the volume of the raw water and the TDS value and the volume of the electrolyzed water. According to the invention, the water hardness can be accurately measured.

Description

Technical Field

[0001] The present invention relates to water hardness detection technology, and in particular to a water hardness detection method and a system thereof. Background Art

[0002] Hardness is an important indicator of water quality. GB 5749-2022 "Sanitary Standards for Drinking Water" limits the hardness of drinking water to no more than 450 mg / L. Excessive water hardness can cause scaling of water-using utensils and bitter drinking taste. For household water purification scenarios, it is urgent to develop a set of water hardness detection methods suitable for household water purification equipment. The professional detection method for determining the hardness of drinking water is the titration method in GB / T5750-2023. Other methods include the kit method, the test paper method, and the calcium / magnesium ion selective electrode method. When using these methods to determine the hardness of water, more professional instrument analysis and chemical subject knowledge reserves are required, and the process is complicated and time-consuming. It is difficult for ordinary household water purification equipment users to obtain the hardness of drinking water using these methods. Summary of the invention

[0003] The main purpose of the present invention is to provide a water hardness detection method and system thereof to solve the problem that the water hardness detection technology of existing household water purification equipment is complex, costly or inaccurate.

[0004] According to one aspect of the present invention, a method for detecting water hardness is provided, which comprises: respectively obtaining a first correlation between a pre-determined total water quality correction factor and the pH of a water body, a second correlation between the total water quality correction factor and the temperature of a water body, and a third correlation between the total water quality correction factor and the TDS of a water body; respectively obtaining a first pH, a first temperature, and a first TDS of raw water, and determining the total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first correlation, determining the total water quality correction factor corresponding to the first temperature as a first correction factor according to the second correlation, and determining the total water quality correction factor corresponding to the first TDS as a second correction factor according to the third correlation; obtaining When determining the first correlation relationship, the second temperature and the second TDS of the water body are measured, and a total water quality correction factor corresponding to the second temperature is determined as a third correction factor according to the second correlation relationship, and a total water quality correction factor corresponding to the second TDS is determined as a fourth correction factor according to the third correlation relationship; a temperature gain is determined according to the first correction factor and the third correction factor, and a TDS gain is determined according to the second correction factor and the fourth correction factor; the baseline correction parameter is corrected according to the temperature gain and the TDS gain to obtain a total correction factor for raw water; and the hardness of the raw water is determined according to the total correction factor for raw water, the TDS value and volume of the raw water, and the TDS value and volume of the electrolyzed water.

[0005] Among them, the step of determining the temperature gain according to the first correction factor and the third correction factor includes: taking the ratio of the first correction factor to the third correction factor as the temperature gain; the step of determining the TDS gain according to the second correction factor and the fourth correction factor includes: taking the ratio of the second correction factor to the fourth correction factor as the TDS gain.

[0006] The reference correction parameter is corrected by the following formula to obtain the total correction factor of raw water: F(w) / η=f(w) / η′×g1×g2, wherein f(w) / η′ represents the reference correction parameter, g1 represents the temperature gain, and g2 represents the TDS gain.

[0007] Among them, when the pH value is lower than the preset segmented area, the first correlation relationship presents a linear decreasing trend, the linear slope is between -0.78 and -2.35, and the linear intercept is between 7.36 and 15.02; when the pH value is higher than or equal to the preset segmented area, the first correlation relationship presents a flat linear relationship, the linear slope is between -0.07 and 0.55, and the linear intercept is between -1.52 and 3.17; wherein the pH value of the preset segmented area is 7.25-7.95.

[0008] The second correlation relationship presents a linear decreasing trend, the linear slope is between -0.07 and -0.010, and the linear intercept is between 1.57 and 2.56.

[0009] The third correlation relationship shows a power function variation trend, the pre-exponential factor of the power function varies between 5.97 and 14.29, and the exponential term varies between -0.113 and -0.356.

[0010] The hardness of raw water is determined by the following formula: C=F(w) / η×(TDS0-V1×TDS1 / V0), wherein F(w) / η represents the total correction factor of raw water, TDS0 represents the TDS value of raw water, TDS1 represents the TDS value of water after electrolysis, V0 represents the volume of raw water, and V1 represents the volume of water after electrolysis.

[0011] According to another aspect of the present invention, there is also provided a water hardness detection system, which includes: a first acquisition module, used to respectively acquire a first correlation relationship between a pre-determined total water quality correction factor and a water body pH, a second correlation relationship between the total water quality correction factor and a water body temperature, and a third correlation relationship between the total water quality correction factor and a water body TDS; a second acquisition module, used to respectively acquire a first pH, a first temperature and a first TDS of raw water, determine the total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first correlation relationship, determine the total water quality correction factor corresponding to the first temperature as a first correction factor according to the second correlation relationship, and determine the total water quality correction factor corresponding to the first TDS as a second correction factor according to the third correlation relationship; a gain determination module, Used to obtain the second temperature and the second TDS of the measured water body when measuring the first correlation relationship, determine the total water quality correction factor corresponding to the second temperature as the third correction factor according to the second correlation relationship, and determine the total water quality correction factor corresponding to the second TDS as the fourth correction factor according to the third correlation relationship; determine the temperature gain according to the first correction factor and the third correction factor, and determine the TDS gain according to the second correction factor and the fourth correction factor; a total correction factor calculation module, used to correct the reference correction parameter according to the temperature gain and the TDS gain to obtain the total correction factor of raw water; a hardness calculation module, used to determine the hardness of raw water according to the total correction factor of raw water, the TDS value and volume of raw water, and the TDS value and volume of water after electrolysis.

[0012] The gain determination module is further configured to use a ratio of the first correction factor to the third correction factor as the temperature gain; and use a ratio of the second correction factor to the fourth correction factor as the TDS gain.

[0013] The total correction factor calculation module obtains the total correction factor of raw water by the following formula: F(w) / η=f(w) / η′×g1×g2, wherein f(w) / η′ represents the reference correction parameter, g1 represents the temperature gain, and g2 represents the TDS gain.

[0014] According to the above technical scheme of the present application, by analyzing the relationship between the total correction factor of water quality and the pH, temperature and TDS of the water body, the benchmark correction parameters as well as the temperature gain and TDS gain are determined, and thus the total correction factor of raw water is determined, thereby obtaining the hardness value of raw water. The technical scheme of the present application has the advantages of simplicity and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 is a schematic diagram of changes in TDS and pH of effluent with electrolysis time according to an embodiment of the present invention;

[0017] Figure 2 is a schematic diagram of the relationship between the electrolytic reaction efficiency and the permanent hardness ratio according to an embodiment of the present invention;

[0018] Figure 3 is a schematic diagram of the relationship between the water quality correction factor and the permanent hardness ratio according to an embodiment of the present invention;

[0019] Figure 4 is a schematic diagram of the relationship between the total correction factor and the permanent hardness ratio according to an embodiment of the present invention;

[0020] Figure 5 is a schematic diagram of the relationship between the permanent hardness ratio and the pH value of the water body according to an embodiment of the present invention;

[0021] Figure 6 is a schematic diagram of the relationship between electrolysis reaction efficiency and pH value of water according to an embodiment of the present invention;

[0022] Figure 7 is a schematic diagram of the relationship between the water quality correction factor and the pH of the water body according to an embodiment of the present invention;

[0023] Figure 8 is a schematic diagram of the relationship between the total correction factor and the pH value of the water body according to an embodiment of the present invention;

[0024] Fig. 9 Schematic diagram of pH being divided into three gears according to an embodiment of the present invention;

[0025] Fig.10 is a schematic diagram of the relationship between raw water TDS and electrolysis reaction efficiency according to an embodiment of the present invention;

[0026] Fig.11 is a schematic diagram of the relationship between the total correction factor and the TDS of the water body according to an embodiment of the present invention;

[0027] Fig.12 is a schematic diagram of the relationship between the electrolysis efficiency coefficient and the water temperature according to an embodiment of the present invention;

[0028] Fig.13 is a schematic diagram of the relationship between the total correction factor and temperature according to an embodiment of the present invention;

[0029] Fig.14 4 is a flow chart of a method for detecting water hardness according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Although the present invention specification may include embodiments in many different forms, for some preferred embodiments described in detail in the specification and shown in the drawings, it should be understood that: these contents disclosed in the present invention specification should be regarded as schematic illustrations of the principles of the present invention, and these shown embodiments are not intended to limit the scope of protection of the present invention.

[0032] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0033] This application uses the electrolysis water solution to detect the hardness of raw water. Specifically, by measuring the TDS (Total Dissolved Solids) difference between raw water and electrolyzed water, the raw water hardness is obtained using a specific mathematical relationship.

[0034] When electrolyzing raw water, the following chemical reactions occur at the cathode:

[0035] (1) 2H2O→2H + +e - +2OH -

[0036] (2) OH - +HCO3 - →CO3 2- +H2O

[0037] (3) Ca 2+ +CO3 2- →CaCO3↓

[0038] (4)Mg 2+ +2OH - →Mg(OH)2↓

[0039] During the electrolysis of water, a large amount of OH is generated in situ on the cathode surface. - . Part of OH - With HCO3 in raw water - The reaction produces CO32- The generated CO3 2- further combines with Ca in the raw water 2+ to form CaCO3, which precipitates on the cathode surface. This process selectively removes a part of Ca in the raw water 2+ concentration, causing a partial decrease in the TDS of the water body. At the same time, another part of OH - combines with Mg in the raw water 2+ to form Mg(OH)2, which also precipitates on the cathode surface. This process selectively removes a part of Mg in the raw water 2+ concentration, further decreasing the TDS of the water body. In an electrochemical experimental system with a certain structure, by measuring the efficiency of the above electrolysis reaction in removing Ca 2+ and Mg 2+ , the raw water hardness value can be obtained from the decrease in TDS between the raw water and the electrolyzed water.

[0040] The derivation process of the raw water hardness calculation formula is as follows:

[0041] Set the TDS values of the raw water and the electrolyzed water as TDS0 and TDS1 (theoretically TDS1 < TDS0), and the volume of the raw water in the experiment as V0 and the volume of the electrolyzed water as V1 (due to the consumption of water and generation of gas during the electrolysis process, theoretically V1 < V0). Then, before and after electrolysis of the raw water:

[0042] Ca 2+ and Mg 2+ Hardness removal amount = TDS0V0 - TDS1V1

[0043] Further set the efficiency coefficient of the electrolysis reaction as η (this value must be determined through experiments), then:

[0044] Raw water hardness = (TDS0V0 - TDS1V1) / ηV0

[0045] Considering the influence of the raw water quality on the electrolysis reaction, a water quality-related coefficient f(w) is introduced for correction. The formula for predicting the raw water hardness is:

[0046] Raw water hardness = f(w) / η × (TDS0 - V1 × TDS1 / V0)

[0047] This principle can be realized through the following embodiments:

[0048] In this embodiment, the electrochemical reactor adopts a cylindrical reactor. To match the household water purification equipment, the reactor can also adopt other shapes. In this embodiment, the cathode material is a circular 316L mesh (mesh number: 100#, diameter 45mm), and other shapes and materials can also be selected. The anode material is a graphite sheet (thickness 2mm, diameter 45mm), which can also be adjusted independently according to the shape of the reactor. The distance between the anode and the cathode is 28mm, and the material is led out to the reactor and connected to the power supply through the Ti sheet as a wire.

[0049] When conducting the optimization test of electrolysis conditions, simulated tap water is used as the object. The preparation of simulated tap water is to add a certain amount of CaCl2, MgSO4, NaHCO3, Na2SO4 and NaCl to the reverse osmosis water (TDS <10) to adjust the water body TDS between 260-268 and the hardness to about 150ppm (calculated as CaCO3). The pH value is adjusted according to the test requirements.

[0050] During the implementation process, the TDS value TDS0 of the raw water is recorded, and V0 is quantitatively added to the reactor. The Ti wire is connected to the cathode and anode respectively, and 24V DC is applied through a power supply to start electrolysis of the raw water. The electrolysis is stopped after a specific time, and the quantitative volume V1 of the electrolyzed water is taken out and TDS1 is measured. The hardness of the electrolyzed water is measured by the titration method specified in GB 5750-2022 to obtain η. Subsequently, the correction factor f(w) / η under different water quality conditions (such as pH, TDS and temperature) is obtained through a large number of experiments to determine the working logic of determining the hardness of the raw water, which will be described in detail below.

[0051] In this embodiment, the electrolysis time needs to be balanced from multiple aspects: 1. After electrolysis, there should be a significant difference between TDS0 and TDS1, so as not to cause a large measurement error; 2. The electrolysis process should not cause a significant temperature rise in the water body and cause a measurement error; 3. The electrolysis process should not cause a significant decrease in the pH of the water body, thereby causing the CaCO3 and Mg(OH)2 deposited on the cathode to dissolve and affect the TDS measurement. 4. The time economy of the entire raw water hardness measurement process.

[0052] refer to Figure 1 , water electrolysis experiment, the TDS of the experimental water is 268ppm, the pH value is 7.36. The electrode material, electrode spacing and electrode area are consistent with the above introduction, and the voltage is 24V.

[0053] Through experimental tests, it was found that for this embodiment, 15 minutes is the optimal time, and the temperature rise before and after electrolysis is 6°C. If it is shorter than 15 minutes, the sensitivity of the hardness sensing method may be further reduced due to the insufficient difference in TDS before and after electrolysis; if it is longer than 15 minutes, it will cause TDS measurement errors caused by a significant decrease in pH. It is worth noting that the water electrolysis time may vary with changes in electrode material, electrode area, electrode spacing and voltage value. Therefore, for a water electrolysis system different from the present embodiment, the above-mentioned curve of the change of the outlet TDS and pH value over time can be used to determine the electrolysis time.

[0054] According to scientific definition, temporary hardness of water refers to the Ca2+ in water combined with bicarbonate and a small amount of carbonate. 2+ Mg 2+ The hardness formed. When the total hardness remains unchanged, if there are fewer bicarbonates in the water, the temporary hardness is low and the permanent hardness is high. According to the chemical mechanism of the embodiment of the present invention, the measured raw water hardness may be low. In addition, when the pH value of the water body is different, the electrochemical performance of the electrochemical reactor varies and causes deviations in the ability to predict the raw water hardness. In addition, the TDS of the water body itself, as a measure of the conductivity of the water body, will also affect the accuracy of the raw water hardness prediction. Finally, changes in water temperature will also affect the accuracy of the raw water hardness prediction. In order to cope with regional and seasonal differences in water quality, it is very important to understand the impact of these parameters on the prediction of raw water hardness. Therefore, the water quality correction factor f(w) is introduced into the formula proposed in the embodiment of the present application as a water quality-related correction.

[0055] First, the effect of the change of temporary hardness ratio in water on the correction factor is investigated. The temporary hardness ratio of simulated water is adjusted by adjusting HCO3 - The amount of addition is varied from 0% to 100%, and the results are referenced Figure 2 .

[0056] from Figure 2 It can be seen that the electrolytic reaction efficiency coefficient η decreases linearly with the increase of permanent hardness ratio, and the linear regression coefficient is 0.997. According to the principle of this embodiment, due to HCO3 - The smaller the amount, the more Ca generated indirectly by electrolysis 2+ and Mg 2+ The less the precipitation, the lower the electrolysis efficiency coefficient. Therefore, when the permanent hardness ratio is lower, the water quality correction factor is closer to 1, indicating that the raw water hardness can be inferred only by the electrolysis efficiency η; when the permanent hardness ratio is higher, the water quality correction factor begins to decrease. On the contrary, the total correction factor f(w) / η increases monotonically with the increase of the permanent hardness ratio. This shows that the higher the permanent hardness of the water body, the more additional correction is needed to correct the low raw water hardness.

[0057] To understand the percentage of permanent hardness in the raw water of a certain place requires additional instruments and methods, which is cumbersome and time-consuming. Therefore, a simpler and more effective parameter is needed to replace the permanent hardness in the water quality of different places.

[0058] from Figure 5 It can be seen that the higher the proportion of permanent hardness, the higher the HCO3 - The lower the concentration, the lower the pH value of the water body. There is a certain correspondence between the two. Moreover, the detection of the pH value of the water body is relatively more convenient. Therefore, the pH value can replace the permanent hardness ratio as a parameter indicator for the prediction and correction of raw water hardness.

[0059] When measuring the curve of the total correction factor f(w) / η changing with the pH value of the water body, in addition to recording the pH value of the measured water body, the TDS value and water temperature of the measured water should also be recorded as important parameters for subsequent hardness prediction. Figure 8 The TDS of the water used in the curve was 264ppm and the temperature was 23.4℃.

[0060] Figure 8 An embodiment of the total correction factor f(w) / η changing trend with the pH value of the water body is shown, and the change curve presents the trend of a piecewise function. The segmented pH value can be a value or a range between 7.25 and 7.95. When the pH value increases from 6.5 to the segmented value or segmented interval, the total correction factor decreases linearly with the increase of pH. The linear slope varies between -0.78 and -2.35, and the linear intercept is between 7.36 and 15.02. When the pH value is higher than the segmented value or segmented interval, the change of the total correction factor is not significant, the linear slope ranges between -0.07 and 0.55, and the intercept ranges between -1.52 and 3.17.

[0061] The reason for the segmented change is that when the pH of the water increases, the HCO3 - As the concentration rises, the electrolysis reaction efficiency coefficient also rises synchronously with the increase in pH. When the pH is greater than the segmented value or segmented interval, the alkalinity of the water body has exceeded the amount required for the electrolysis reaction, so the electrolysis efficiency coefficient η remains unchanged after this pH value or interval. Similarly, the water quality correction factor f(w) gradually increases from pH = 6.58. But the difference is that after the pH segmented interval, f(w) does not remain unchanged, but increases further. The total correction factor f(w) / η shows an opposite trend to the electrolysis efficiency within the pH range examined. At lower pH, due to the smaller electrolysis efficiency coefficient, the largest total correction factor is required to compensate for HCO3 - The hardness prediction deviation caused by severe deficiency. As the pH gradually increases, the required amount of compensation begins to decrease and tends to be stable after the pH segmentation interval.

[0062] from Figure 8 It can also be seen that the water hardness detection method of this embodiment is sensitive to the pH value of the water body. The fluctuation or difference of the pH value of the water body over time, season and region may affect the accuracy of the hardness detection in this embodiment. If the pH value range within the range of ±15% of the hardness detection error is analyzed at each experimentally measured pH, it can be obtained Fig. 9 .

[0063] from Fig. 9 It can be seen that in order to simplify the impact of pH fluctuations on raw water hardness detection, it can be divided into 3 "gears". The pH range of the first gear is 6.5-7.08, and the pH range of the second gear is 6.96-7.43. The pH range of the third gear is 7.48-8.5. In each gear, no matter how the pH changes within this range, the error of raw water hardness measurement is within ±15%. This function can be integrated into the electronic control logic, which is convenient for installers and users to adjust by themselves, reducing frequent calibration and maintenance.

[0064] In addition to the pH change of water, raw water TDS also has daily and regional changes and differences. From the perspective of electrochemical principles, the raw water TDS value represents the quality of raw water conductivity, which will also affect the efficiency of electrolysis current. The accuracy of raw water hardness detection will be affected by these factors. Therefore, this example also explores the impact of raw water TDS on the total correction factor.

[0065] like Fig.10 As shown, the electrolysis efficiency coefficient is almost unchanged in the range of TDS from 270ppm to 610ppm, ranging from 57% to 59%. This shows that the key control factor of the electrolysis reaction is not TDS. But as mentioned earlier, the effect of TDS on the electrolysis process lies in the conduction of current, which is reflected in the curve of the total correction factor changing with TDS and makes it decrease in the power function trend as a whole. The pre-exponential factor of the power function varies from 5.97 to 14.29, and the exponential term varies from -0.113 to -0.356.

[0066] like Fig.11 As shown, when the TDS is higher, the total correction factor is smaller, and the total correction factor of water quality and the TDS of the water body show a power function change trend. This is because the higher the raw water TDS value is, the more conducive it is to the conduction of current, and the smaller the loss of electrolysis current conduction is. In the experimental process of this embodiment, it was also detected that as the raw water TDS increases, the temperature rise of the water body after electrolysis also increases. For example, when the raw water temperature is 23.4°C and the raw water TDS = 611ppm, the temperature rise of the water body after electrolysis reaches 10°C.

[0067] In addition, the raw water temperature is also an important factor affecting the raw water hardness detection. Relatively low water temperature will significantly inhibit the electrolytic activity, and Ca2+ and Mg 2+ It has slower kinetics. Therefore, low temperature may be a challenge affecting the accuracy of raw water detection. The effect of temperature on the electrolysis efficiency coefficient η and the total correction factor was also explored in this example.

[0068] like Fig.12 In the embodiment shown, the temperature range of the investigation is 5 to 40°C. The lower the temperature, the lower the electrolysis efficiency coefficient, which is only 38% at 4.8°C. The electrolysis efficiency coefficient increases significantly with the increase of temperature. When the temperature is >30°C, the electrolysis efficiency coefficient is stable at 55%. At low temperatures, the electrolytic activity and the diffusion dynamics of hardness ions are limited, so the electrolysis efficiency coefficient is low; when the temperature rises, the electrolytic activity increases and the diffusion of hardness ions is also enhanced, so the electrolysis efficiency coefficient is significantly improved; when the temperature is >30°C, the electrolytic activity and the diffusion dynamics of hardness ions are close to saturation, so when the temperature is further increased, the electrolysis efficiency coefficient remains stable.

[0069] Correspondingly, Fig.13 The embodiment shown shows that the total correction factor f(w) / η shows a regular change of linear decrease with increasing temperature. The linear slope of the function curve varies in the range of -0.07 to -0.010, and the intercept varies in the range of 1.57 to 2.56.

[0070] It can be seen that the total correction factor f(w) / η and the electrolysis efficiency coefficient have opposite changes. When the temperature is low, the total correction factor f(w) / η is higher because the lower electrolysis efficiency coefficient η needs to be corrected. As the temperature rises, the total correction factor gradually decreases.

[0071] The above study discussed three important factors (pH, temperature and TDS) that affect the detection of raw water hardness. Due to the daily and regional changes in water quality, it is necessary to select the primary factor as a benchmark and make real-time corrections through the synergy of other factors.

[0072] refer to Fig.14 According to the water hardness detection method of the embodiment of the present invention, the method comprises at least the following steps:

[0073] Step S1402, respectively obtain a first correlation between the total water quality correction factor and the pH of the water body, a second correlation between the total water quality correction factor and the water body temperature, and a third correlation between the total water quality correction factor and the TDS of the water body within a predetermined range. The total water quality correction factor is a parameter for correcting the influence of changes in water composition, temperature, ion concentration and pH value on the electrolysis process.

[0074] When testing the water hardness of a certain region or city, it is necessary to determine in advance the relationship between the total water quality correction factor f(w) / η and the pH, temperature and TDS of the region, including:

[0075] Combined with reference Figure 8 The relationship between the total water quality correction factor f(w) / η and the pH of the water body presents a piecewise function change form:

[0076] When the pH of the water body is less than the segmented area, the function curve of the first correlation relationship shows a linear decreasing trend, wherein the linear slope is between -0.78 and -2.35, and the linear intercept is between 7.36 and 15.02. In some embodiments of the present application, the pH value of the segmented area may be between 7.25-7.95. For example, when the pH of the water body is <7.84, the functional relationship of f(w) / η with the pH of the water body (the first correlation relationship) is: f(w) / η=-1.3475×pH+12.4.

[0077] When the pH value of the water body is greater than or equal to the segmented area, the function curve of the first correlation relationship presents a gentle linear relationship, wherein the linear slope is between -0.07 and 0.55, and the linear intercept is between -1.52 and 3.17. In some embodiments of the present application, the pH value of the segmented area may be between 7.25 and 7.95. For example, when the pH value of the segmented area is ≥ When it is 7.84, the functional relationship between f(w) / η and the pH of the water body is: f(w) / η=0.2757×pH-0.29.

[0078] Combined with reference Fig.11 , the relationship between the total water quality correction factor f(w) / η and the TDS of the water body presents a power function decreasing form. In some embodiments of the present application, the pre-exponential factor of the power function varies between 5.97 and 14.92, and the exponential term varies between -0.113 and -0.356. For example, the functional relationship between f(w) / η and the TDS of the water body (the third correlation relationship) can be: f(w) / η=11.122×(σ / TDS) -0.311 , where σ represents the conductivity of raw water.

[0079] Combined with reference Fig.13 , the relationship between the total water quality correction factor f(w) / η and the water body temperature shows a linear decreasing functional change trend. In some embodiments of the present application, the linear slope is between -0.07 and -0.010, and the linear intercept is between 1.57 and 2.56. For example, the functional relationship between f(w) / η and the water body temperature (the second correlation relationship) may be: f(w) / η=-0.0121×T+2.24, where T represents temperature.

[0080] Step S1404, respectively obtain the first pH, first temperature and first TDS of the raw water, determine the total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first association relationship, determine the total water quality correction factor corresponding to the first temperature as a first correction factor according to the second association relationship, and determine the total water quality correction factor corresponding to the first TDS as a second correction factor according to the third association relationship.

[0081] The raw water in the area is electrolyzed, and the pH value (first pH) of the raw water is measured using a pH meter. Based on the relationship between the total correction factor and the pH of the water body, the total water quality correction factor corresponding to the pH value of the raw water is determined as a reference correction parameter. Then, the temperature value (first temperature) of the raw water is measured by a temperature probe, and based on the relationship between the total correction factor and the temperature of the water body, the correction factor (first correction factor) corresponding to the temperature value (first temperature) of the raw water is determined. Next, the TDS value (first TDS) of the raw water is measured by a TDS probe, and based on the relationship between the total correction factor and the TDS, the correction factor (second correction factor) corresponding to the TDS value (first TDS) of the raw water is determined.

[0082] Step S1406, obtaining the second temperature and the second TDS of the measured water body when measuring the first correlation relationship, determining the total water quality correction factor corresponding to the second temperature as the third correction factor according to the second correlation relationship, and determining the total water quality correction factor corresponding to the second TDS as the fourth correction factor according to the third correlation relationship; determining the temperature gain according to the first correction factor and the third correction factor, and determining the TDS gain according to the second correction factor and the fourth correction factor.

[0083] In step S1402, when measuring the relationship between the total correction factor f(w) / η of the water quality in the area and the pH (first correlation), the water temperature value (second temperature) and TDS value (second TDS) of the measured water body should also be recorded. The second temperature value and the second TDS value are obtained, and the total correction factor (third correction factor) of the water quality corresponding to the second temperature is determined according to the relationship between the total correction factor and the water body temperature (second correlation); the total correction factor (fourth correction factor) corresponding to the second TDS value of the raw water is determined according to the relationship between the total correction factor and TDS (third correlation). Then, the first correction factor and the third correction factor are compared, that is, the ratio of the former to the latter, as the temperature value gain g1; the second correction factor and the fourth correction factor are compared, that is, the ratio of the former to the latter, as the TDS value gain g2.

[0084] Step S1408: Correct the reference correction parameter according to the temperature gain and the TDS gain to obtain a total correction factor for raw water.

[0085] According to an embodiment of the present invention, the corresponding reference correction parameter is determined according to the pH value of the raw water, and the corresponding temperature value gain is determined according to the temperature and the corresponding TDS value gain is determined according to the TDS, and the reference correction parameter is corrected. Specifically, the reference correction parameter is corrected by the following formula to obtain the total correction factor of raw water:

[0086] F(w) / η=f(w) / η′×g1×g2, where f(w) / η′ represents a reference correction parameter, g1 represents a temperature gain, and g2 represents a TDS gain.

[0087] Step S1410, determining the hardness of the raw water according to the raw water total correction factor, the TDS value and volume of the raw water, and the TDS value and volume of the electrolyzed water.

[0088] Specifically, the hardness of raw water is calculated by the following formula:

[0089] C=F(w) / η×(TDS0-V1×TDS1 / V0), wherein F(w) / η represents the total correction factor of raw water, TDS0 represents the TDS value of raw water, TDS1 represents the TDS value of water after electrolysis, V0 represents the volume of raw water, and V1 represents the volume of water after electrolysis.

[0090] The present invention is described in detail below with reference to specific examples.

[0091] Detect the water hardness of a certain municipal tap water. First, it is necessary to determine the relationship between the total water quality correction factor f(w) / η and pH, TDS and temperature. Then, the pH of the tap water is measured by a pH meter to be 7.73 (i.e., the first pH mentioned above), the water temperature is measured by a temperature probe to be 18.8°C (i.e., the first temperature mentioned above), and the TDS of the water body is measured by a TDS probe to be 223ppm (i.e., the first TDS mentioned above).

[0092] When pH=7.73, according to the relationship between the total water quality correction factor and pH (the first correlation relationship), f(w) / η′=2.08 is obtained, which is used as the reference correction parameter.

[0093] When the water temperature is 18.8°C, according to the relationship between the total water quality correction factor and the temperature (the second correlation), f(w) / η=2.00 (the first correction factor) is obtained. The water temperature obtained when the relationship between f(w) / η and pH (the first correlation) is measured is 23.4°C (the second temperature). According to the relationship between f(w) / η and temperature (the second correlation), the total water quality correction factor f(w) / η=2.00 (the third correction factor) corresponding to the second temperature is obtained. The first correction factor is compared with the third correction factor, that is, the ratio of the former to the latter is used as the temperature value gain, so the temperature gain g1=1.

[0094] When TDS=223ppm, according to the variation relationship between the total water quality correction factor and TDS (third correlation relationship), f(w) / η=2.07 (second correction factor) is obtained. The TDS of the water body obtained when the variation relationship between f(w) / η and pH (first correlation relationship) is measured above is 264ppm (second TDS), and the total water quality correction factor f(w) / η=2.00 (fourth correction factor) corresponding to the second TDS is obtained according to the variation relationship between f(w) / η and TDS (third correlation relationship). The second correction factor is compared with the fourth correction factor, that is, the ratio of the former to the latter is taken as the TDS gain, so the TDS gain g2=1.03.

[0095] The reference correction parameters are corrected according to the temperature gain and the TDS gain to obtain the total correction factor of raw water, and the total correction factor of raw water is F(w) / η=2.08×1×1.03=2.15.

[0096] The raw water hardness is calculated according to the formula: Raw water hardness = F(w) / η×(TDS0-V1×TDS1 / V0), where V1 / V0 is 0.956. Three electrolysis (24V for 15min) were performed on the municipal tap water in the area. The TDS1 obtained after electrolysis were 161, 158, and 157 respectively. The raw water hardness predicted by the above parameters and formula was 148.36ppm, 154.52ppm, and 156.57ppm respectively.

[0097] The existing raw water hardness measured by titration is 152.14 ppm. When the hardness detection method according to the present invention is compared with the measured data of the titration method, the errors are -2.48%, 1.57% and 2.92% respectively. Therefore, the present application embodies good accuracy.

[0098] It should be noted that the shape of the curve of f(w) / η varying with pH, ​​temperature and TDS varies with the structure of the electrochemical reactor, that is, the electrode area, electrode material and electrode spacing, and will also change according to the specific water quality conditions in different regions.

[0099] According to an embodiment of the present application, a water hardness detection system is also provided, which includes:

[0100] A first acquisition module is used to respectively acquire a first correlation relationship between a pre-determined total water quality correction factor and a pH value of a water body, a second correlation relationship between the total water quality correction factor and a temperature of a water body, and a third correlation relationship between the total water quality correction factor and a TDS of a water body;

[0101] a second acquisition module, for respectively acquiring a first pH, a first temperature, and a first TDS of the raw water, determining a total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first association relationship, determining a total water quality correction factor corresponding to the first temperature as a first correction factor according to the second association relationship, and determining a total water quality correction factor corresponding to the first TDS as a second correction factor according to the third association relationship;

[0102] a gain determination module, configured to obtain a second temperature and a second TDS of the measured water body when the first correlation relationship is determined, determine a total water quality correction factor corresponding to the second temperature as a third correction factor according to the second correlation relationship, and determine a total water quality correction factor corresponding to the second TDS as a fourth correction factor according to the third correlation relationship; determine a temperature gain according to the first correction factor and the third correction factor, and determine a TDS gain according to the second correction factor and the fourth correction factor;

[0103] A total correction factor calculation module, used for correcting the reference correction parameter according to the temperature gain and the TDS gain to obtain a total correction factor of raw water;

[0104] The hardness calculation module is used to determine the hardness of the raw water according to the total correction factor of the raw water, the TDS value and volume of the raw water, and the TDS value and volume of the electrolyzed water.

[0105] The gain determination module is further configured to use a ratio of the first correction factor to the third correction factor as the temperature gain; and use a ratio of the second correction factor to the fourth correction factor as the TDS gain.

[0106] Furthermore, the total correction factor calculation module obtains the total correction factor of raw water through the following formula: F(w) / η=f(w) / η′×g1×g2, wherein f(w) / η′ represents the reference correction parameter, g1 represents the temperature gain, and g2 represents the TDS gain.

[0107] In summary, the embodiments of the present application have at least the following advantages:

[0108] (1) It can measure the hardness of raw water with a simple method;

[0109] (2) Specific detection of water hardness with high accuracy;

[0110] (3) The cost is relatively low.

[0111] The operation steps of the method of the present invention correspond to the structural features of the system, and can be referenced to each other, and will not be described in detail again.

[0112] Although the present disclosure has been described in detail with reference to the specific embodiments of the present application, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the embodiments. Therefore, the present application is intended to cover the modifications and variations of the present application, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of the claims of the present application and their equivalents.

[0113] In addition, the features disclosed in the above description or claims or drawings, in their specific form or according to the mode for performing the disclosed functions or the method or process for obtaining the disclosed results, can be used to implement the present application in their different forms alone or in any combination of these features, as appropriate. Specifically, one or more features of any embodiment described in the present application can be combined with one or more features of any other embodiment described in the present application.

[0114] Protection may also be sought for any features disclosed in any one or more of the publications cited in conjunction with the present application and / or incorporated by reference.

Claims

1. A method for detecting water hardness, It is characterized in that include: Respectively obtaining a first correlation relationship between a pre-determined total water quality correction factor and pH of a water body, a second correlation relationship between the total water quality correction factor and temperature of a water body, and a third correlation relationship between the total water quality correction factor and TDS of a water body; respectively obtaining a first pH, a first temperature, and a first TDS of the raw water, determining a total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first association relationship, determining a total water quality correction factor corresponding to the first temperature as a first correction factor according to the second association relationship, and determining a total water quality correction factor corresponding to the first TDS as a second correction factor according to the third association relationship; Obtaining a second temperature and a second TDS of the measured water body when measuring the first correlation relationship, determining a total water quality correction factor corresponding to the second temperature as a third correction factor according to the second correlation relationship, and determining a total water quality correction factor corresponding to the second TDS as a fourth correction factor according to the third correlation relationship; determining a temperature gain according to the first correction factor and the third correction factor, and determining a TDS gain according to the second correction factor and the fourth correction factor; Correcting the reference correction parameter according to the temperature gain and the TDS gain to obtain a total correction factor for raw water; The hardness of the raw water is determined based on the raw water total correction factor, the TDS value and volume of the raw water, and the TDS value and volume of the electrolyzed water.

2. The water hardness detection method according to claim 1, It is characterized in that The step of determining the temperature gain according to the first correction factor and the third correction factor comprises: taking the ratio of the first correction factor to the third correction factor as the temperature gain; The step of determining the TDS gain according to the second correction factor and the fourth correction factor includes: taking the ratio of the second correction factor to the fourth correction factor as the TDS gain.

3. The water hardness detection method according to claim 1 or 2, It is characterized in that The reference correction parameter is corrected by the following formula to obtain the total correction factor of raw water: F(w) / η=f(w) / η′×g1×g2, where f(w) / η′ represents the reference correction parameter, g1 represents the temperature gain, and g2 represents the TDS gain.

4. The water hardness detection method according to claim 1, It is characterized in that When the pH value is lower than the preset segmented area, the first correlation relationship presents a linear decreasing trend, the linear slope is between -0.78 and -2.35, and the linear intercept is between 7.36 and 15.02; When the pH value is higher than or equal to the preset segmented area, the first correlation relationship presents a gentle linear relationship, the linear slope is between -0.07 and 0.55, and the linear intercept is between -1.52 and 3.17; Wherein, the pH value of the preset segmented area is 7.25 to 7.

95.

5. The water hardness detection method according to claim 1, It is characterized in that The second correlation relationship presents a linear decreasing trend, the linear slope is between -0.07 and -0.010, and the linear intercept is between 1.57 and 2.

56.

6. The water hardness detection method according to claim 1, It is characterized in that The third correlation relationship presents a power function variation trend, the pre-exponential factor of the power function varies between 5.97 and 14.29, and the exponential term varies between -0.113 and -0.

356.

7. The water hardness detection method according to claim 1, It is characterized in that The hardness of raw water is determined by the following formula: C=F(w) / η×(TDS 0 -V 1 ×TDS 1 / V 0 ), where F(w) / η represents the total correction factor of raw water, TDS 0 Indicates the raw water TDS value, TDS 1 Indicates the TDS value of water after electrolysis, V 0 Represents the volume of raw water, V 1 Indicates the volume of water after electrolysis.

8. A water hardness detection system, It is characterized in that include: A first acquisition module is used to respectively acquire a first correlation relationship between a pre-determined total water quality correction factor and a pH value of a water body, a second correlation relationship between the total water quality correction factor and a temperature of a water body, and a third correlation relationship between the total water quality correction factor and a TDS of a water body; a second acquisition module, for respectively acquiring a first pH, a first temperature, and a first TDS of the raw water, determining a total water quality correction factor corresponding to the first pH as a reference correction parameter according to the first association relationship, determining a total water quality correction factor corresponding to the first temperature as a first correction factor according to the second association relationship, and determining a total water quality correction factor corresponding to the first TDS as a second correction factor according to the third association relationship; a gain determination module, configured to obtain a second temperature and a second TDS of the measured water body when measuring the first correlation relationship, determine a total water quality correction factor corresponding to the second temperature as a third correction factor according to the second correlation relationship, and determine a total water quality correction factor corresponding to the second TDS as a fourth correction factor according to the third correlation relationship; determine a temperature gain according to the first correction factor and the third correction factor, and determine a TDS gain according to the second correction factor and the fourth correction factor; A total correction factor calculation module, used for correcting the reference correction parameter according to the temperature gain and the TDS gain to obtain a total correction factor of raw water; The hardness calculation module is used to determine the hardness of the raw water according to the total correction factor of the raw water, the TDS value and volume of the raw water, and the TDS value and volume of the electrolyzed water.

9. The water hardness detection system according to claim 8, It is characterized in that The gain determination module is further configured to: taking the ratio of the first correction factor to the third correction factor as the temperature gain; The ratio of the second correction factor to the fourth correction factor is used as the TDS gain.

10. The water hardness detection system according to claim 8 or 9, It is characterized in that The total correction factor calculation module obtains the raw water total correction factor by the following formula: F(w) / η=f(w) / η′×g1×g2, where f(w) / η′ represents the reference correction parameter, g1 represents the temperature gain, and g2 represents the TDS gain.

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