Water salinity measurement and correction method and system for seawater desalination

Abstract

The invention relates to the technical field of salinity measurement, in particular to a water salinity measurement and correction method and system for seawater desalination. The method comprises the following steps: acquiring the conductivity, the water outlet side pressure and the salinity of each sensor on two sides of the RO component in the seawater desalination process; for each sensor, according to the similar condition of the change characteristics of the conductivity of each time period in the historical period and the current time period and the fluctuation difference of the conductivity of the historical period and the current period, screening the matched time period; the Kalman filtering gain during conductivity denoising is adjusted by combining the conductivity of the periods in which the current time period and the matching time period are located, and the conductivity is filtered; according to the conductivity of the sensors on the water inlet side and the water outlet side, the corrected conductivity and the pressure on the water outlet side, the pollution degree is obtained, the level of the RO assembly is combined, the salinity measurement interference index is determined, then the Kalman filtering gain during salinity denoising is adjusted, and the salinity is filtered. According to the invention, the accuracy of salinity determination is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of salinity measurement, and in particular to a method and system for measuring and correcting the salinity of water quality for seawater desalination. Background Art

[0002] Desalination is the process of removing salt and impurities from seawater, converting it into fresh water suitable for human consumption. The desalination process involves pre-treating the raw seawater, including coagulation and sedimentation, media filtration, and sterilization and algae removal. The pre-treated seawater is then transferred to a reverse osmosis desalination system, where it overcomes osmotic pressure and passes through a reverse osmosis membrane to separate water from impurities such as salt. Post-treatment (RO water production and mineralization adjustments) is then performed, with the final product water and brine being output separately. Salinity measurement in the desalination process typically requires sensors to monitor water quality at key steps in the desalination process to achieve salinity measurement.

[0003] Existing salinity measurement methods for seawater desalination systems are unable to promptly capture water quality fluctuations during the desalination process, resulting in inaccurate salinity measurements. For example, changes in the salinity of the raw seawater inflow and the degree of contamination of RO components during the desalination process can cause water quality parameters to fluctuate and may interfere with sensor detection results, thereby affecting the accuracy of salinity measurements. Summary of the Invention

[0004] In order to solve the problem of inaccurate measurement results in the process of measuring water salinity in existing methods, the purpose of the present invention is to provide a method and system for measuring and correcting water salinity for seawater desalination. The technical solutions adopted are as follows: In a first aspect, the present invention provides a method and system for measuring and correcting salinity of water quality for seawater desalination, the method comprising the following steps: Obtain the conductivity, outlet pressure, and salinity of each sensor on both sides of the RO component during the desalination process. The desalination process includes multiple historical cycles and a current cycle. Each cycle contains multiple time periods, and the current time period is the time period at the current moment. For each sensor, based on the similarity of conductivity change characteristics between each period in the historical cycle and the current period, and the conductivity fluctuation difference between the historical period and the current period, the matching period of the current period in each historical cycle is selected. The Kalman filter gain is adjusted during conductivity denoising based on the conductivity at all times in the current period and the conductivity fluctuation difference between the current period and the period in which the matching period belongs. The conductivity filter is then used to obtain the corrected conductivity. The contamination level of the RO component at each moment is determined based on the conductivity and corrected conductivity of the sensors at the inlet and outlet sides of the RO component, as well as the outlet pressure. The salt measurement interference index corresponding to the RO component is determined based on the contamination level and the level of the RO component. The Kalman filter gain is adjusted during salinity denoising based on the salt measurement interference index, and the salinity is filtered to obtain the corrected salinity.

[0005] Preferably, the method of screening the matching period of the current period in each historical period according to the similarity of the conductivity change characteristics between each period in the historical period and the current period and the conductivity fluctuation difference between the historical period and the current period includes: For any period: The ratio between the range of the conductivity at all times in any period and the duration of any period is recorded as the conductivity characteristic value of any period; According to the difference between the conductivity characteristic value of the current period and each period in the historical period, the conductivity fluctuation similarity index of the current period and each period in the historical period is obtained; For any historical period: the period corresponding to the maximum value of the conductivity fluctuation similarity index in the historical period and the current period is used as the matching period of the current period in the historical period.

[0006] Preferably, the adjustment of the Kalman filter gain during conductivity denoising based on the conductivity at all times in the current time period and the conductivity fluctuation difference between the current time period and the period in which the current time period matches the current time period includes: For either sensor: Calculate the DTW distance between the conductivity curve of each historical period and the conductivity curve of the current period respectively, where the conductivity curve of each period is obtained by curve fitting the conductivity at all moments in the period; Calculate the first average value of the conductivity at all times within each matching period respectively; multiply the DTW distance between the conductivity curve of the period in which each matching period falls and the conductivity curve of the current period by the corresponding first average value, and record it as the first product corresponding to each matching period; and take the average value of the first products corresponding to all matching periods as the conductivity prediction mean value for the current period; Calculating the difference between the conductivity at each moment in the current time period and the predicted conductivity mean value as a first difference value corresponding to each moment in the current time period; calculating the average value of the first difference values ​​corresponding to all moments in the current time period; and taking the sum of the conductivity at each moment in the current time period and the average value of the first difference values ​​as the predicted value at each moment in the current time period; The difference between the conductivity at each moment in the current period and the corresponding predicted value is used as the difference index at each moment; Obtaining an error factor of the any one sensor at a current moment according to the DTW distance between the conductivity curves of the any one sensor and each of the remaining sensors in the current cycle and the difference index; The error factor is used to adjust the Kalman filter gain during conductivity denoising.

[0007] Preferably, obtaining the error factor of any one sensor at the current moment according to the DTW distance between the conductivity curve of any one sensor and each of the remaining sensors in the current cycle and the difference index includes: Calculating an average of the DTW distances between the conductivity curves of any one sensor and all other sensors in the current cycle; Calculate a first ratio between the difference index at the current moment and the average difference index of all moments in the current period; The product of the average value of the DTW distance and the first ratio is determined as the error factor of the any sensor in the current period.

[0008] Preferably, the step of adjusting the Kalman filter gain during conductivity denoising using the error factor includes: The difference between the constant 1 and the error factor is used as a first adjustment coefficient; The product of the first adjustment coefficient and the initial gain of the Kalman filter when denoising the conductivity is used as the adjusted Kalman filter gain.

[0009] Preferably, obtaining the contamination degree of the RO component at each moment according to the conductivity and the corrected conductivity of the sensors at the water inlet and water outlet of the RO component, as well as the water outlet pressure, comprises: For any moment: Calculating a second ratio between the corrected conductivity of the sensor on the water inlet side of the RO component and the corresponding conductivity at any moment, and a third ratio between the corrected conductivity of the sensor on the water outlet side of the RO component and the corresponding conductivity; The contamination level of the RO component at any moment is obtained based on the product of the second ratio and the third ratio, the difference between the second ratio and the third ratio, and the outlet water pressure. The product of the second ratio and the third ratio and the outlet water pressure are both positively correlated with the contamination level, and the difference between the second ratio and the third ratio is negatively correlated with the contamination level.

[0010] Preferably, the determining of the salt measurement interference index corresponding to the RO component in combination with the pollution degree and the level of the RO component includes: The difference between the pollution level at the current moment and the pollution level after the previous flushing at the current moment is taken as the pollution level growth amplitude; The salt measurement interference index corresponding to the RO component is obtained according to the pollution degree after the previous flushing at the current moment, the pollution degree growth amplitude, the component level and the time interval between the current moment and the previous flushing at the current moment.

[0011] Preferably, the salt measurement interference index corresponding to the RO component is obtained according to the pollution degree after the previous flushing at the current moment, the pollution degree growth amplitude, the level of the component, and the time interval between the current moment and the previous flushing at the current moment, including: Calculating a second product of the contamination level after the previous flush at the current moment and the magnitude of the contamination level increase, and a third product of the level of the RO component and the time interval between the current moment and the previous flush at the current moment; The ratio of the second product to the third product is determined as the salt measurement interference index corresponding to the RO component.

[0012] Preferably, the adjusting the Kalman filter gain during salinity denoising based on the salt measurement interference index includes: calculating a second difference between the constant 1 and the salt determination interference index; The product of the second difference and the initial gain of the Kalman filter when denoising the salt measurement interference index is used as the adjusted Kalman filter gain.

[0013] In a second aspect, the present invention provides a system for measuring and correcting the salinity of water used in seawater desalination, the system being used to implement the above-mentioned method, the system comprising: The data acquisition module is used to obtain the conductivity, outlet pressure, and salinity of each sensor on both sides of the RO component during the desalination process. The desalination process includes multiple historical cycles and the current cycle. Each cycle contains multiple time periods, and the current time period is the time period at the current moment. A first correction module is configured to, for each sensor, select a matching period for the current period within each historical period based on the similarity between the conductivity change characteristics of each period within the historical period and the current period, and the conductivity fluctuation difference between the historical period and the current period; adjust the Kalman filter gain during conductivity denoising based on the conductivity at all times within the current period and the conductivity fluctuation difference between the current period and the period in which the matching period lies, and perform conductivity filtering to obtain a corrected conductivity; a calculation module for obtaining the contamination level of the RO component at each moment based on the conductivity and corrected conductivity of the sensors at the inlet and outlet sides of the RO component, as well as the outlet pressure; and determining the salt measurement interference index corresponding to the RO component based on the contamination level and the level of the RO component; The second correction module is used to adjust the Kalman filter gain during salinity denoising based on the salt measurement interference index, and to filter the salinity to obtain the corrected salinity.

[0014] The present invention has at least the following beneficial effects: The present invention monitors the conductivity and outlet pressure of each sensor on both sides of an RO component during a seawater desalination process, selects a matching period for the current period based on the similarity of conductivity change characteristics between each period in a historical cycle and the current period and the conductivity fluctuation difference between the historical cycle and the current period, adjusts the Kalman filter gain based on the conductivity at all times in the current period and the conductivity fluctuation difference between the current period and the period in which the matching period belongs, and then filters the conductivity collected by the sensor. The contamination degree of the RO component after flushing is evaluated based on the conductivity and corrected conductivity of the sensors on the inlet and outlet sides of the RO component, as well as the outlet pressure. The salt measurement interference index corresponding to the RO component is determined based on the level of the RO component, and the Kalman filter gain is adjusted during salinity denoising, thereby achieving filtering processing of the salinity data and improving the accuracy of salinity measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A flow chart of a method and system for measuring and correcting salinity of water used in seawater desalination provided by an embodiment of the present invention; Figure 2 This is a structural block diagram of a system for measuring and correcting the salinity of water used in seawater desalination provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a method and system for measuring and correcting the salinity of water quality for seawater desalination proposed by the present invention in conjunction with the accompanying drawings and preferred embodiments.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0019] The following describes in detail a method and system for measuring and correcting salinity of water quality for seawater desalination provided by the present invention with reference to the accompanying drawings.

[0020] An embodiment of a method for measuring and correcting salinity of water used in seawater desalination: The specific scenario targeted by this embodiment is that during the seawater desalination process, the acquisition of water quality salinity data will be affected by various factors, resulting in the inability to timely capture water quality fluctuations during the seawater desalination process, making the measurement results of water quality salinity during the desalination process inaccurate. This embodiment will correct the error detection by combining the degree of correlation between sensors corresponding to different seawater desalination steps and the deviation from the predicted value. Based on the corrected data, the contamination level of the RO component is obtained, and the salt measurement value is corrected according to the contamination level to improve the accuracy of the salinity measurement results.

[0021] This embodiment proposes a method for measuring and correcting the salinity of water used in seawater desalination. Figure 1 As shown, a method for measuring and correcting salinity of water quality for seawater desalination in this embodiment includes the following steps: Step S1, obtaining the conductivity, outlet pressure and salinity of each sensor on both sides of the RO component during the seawater desalination process; the seawater desalination process includes multiple historical cycles and a current cycle, each cycle includes multiple time periods, and the current time period is the time period at the current moment.

[0022] First, during the desalination process, inductive conductivity sensors are installed on the inlet and outlet sides of the RO module. These sensors collect conductivity data. In this embodiment, the conductivity data collection frequency is set to once per second. In specific applications, the user can adjust this frequency based on the specific situation. It should be noted that there can be more than one RO module, and each RO module has its own corresponding level. This embodiment uses one RO module as an example, and the method provided in this embodiment can be applied to other RO modules. Simultaneously, the pressure on the outlet side of the RO module is collected during the desalination process.

[0023] In industrial seawater desalination, conductivity is often used to indirectly measure seawater salinity. Conductivity can reflect the concentration of dissolved salts in seawater. Fluctuations in seawater salinity usually cause certain correlated fluctuations in the conductivity sensor values ​​at different links. Therefore, the electrolysis rate at the next moment is predicted based on the conductivity values ​​monitored by each conductivity sensor over a relatively short period of time.

[0024] The salinity of natural seawater is affected by factors such as season, tide, and rainfall, and shows continuous changes in the short term. That is, the salinity of seawater usually changes according to a certain fluctuation trend in a relatively short period of time.

[0025] Since 12.4 hours is approximately the half-tidal period of seawater, a monitoring period of 12.4 hours is used. The desalination process is divided into multiple cycles based on the length of the monitoring period. The last cycle of the desalination process is regarded as the current cycle, which includes the current moment. All cycles before the current cycle are recorded as historical cycles.

[0026] Because multiple sensors are provided, this embodiment uses one sensor as an example for illustration; the method provided in this embodiment can be used to process other sensors. Specifically, for any sensor and any cycle, a curve fitting is performed on the conductivity collected by the sensor at all times within the cycle, and the maximum point on the curve is obtained. The curve is then divided using the maximum point as a segmentation point to obtain multiple curve segments, each of which corresponds to a time period, thus dividing the cycle into multiple time periods. This method is used to divide each cycle into multiple time periods, with the last time period in the current cycle being recorded as the current time period.

[0027] Step S2: For each sensor, based on the similarity of the conductivity change characteristics between each period in the historical period and the current period and the conductivity fluctuation difference between the historical period and the current period, select the matching period of the current period in each historical period; based on the conductivity at all times in the current period and the conductivity fluctuation difference between the current period and the period in which the matching period belongs, adjust the Kalman filter gain during conductivity denoising, and perform conductivity filtering to obtain a corrected conductivity.

[0028] Seawater salinity typically exhibits repetitive fluctuations over a short period of time, such as increasing salinity at high tide and decreasing at low tide. Therefore, we screened historical periods with conductivity fluctuations similar to the current period. We then used the similarity between the conductivity time series fluctuations measured by the conductivity sensor in each historical period and the current period to predict conductivity.

[0029] For any time period within a historical or current cycle, the ratio of the conductivity range at all moments within that period to the duration of that period is recorded as the conductivity characteristic value for that period. This method can be used to obtain the conductivity characteristic value for each time period within the historical period and for each time period within the current cycle.

[0030] Next, we will use a historical period as an example to illustrate the method provided in this embodiment. The method provided in this embodiment can be used to process other historical periods. Based on the difference between the conductivity characteristic values ​​of the current period and each period in the historical period, the conductivity fluctuation similarity index of the current period and each period in the historical period is obtained. In this embodiment, a calculation formula for the conductivity fluctuation similarity index is given. The conductivity fluctuation similarity index of the current period and the period in the historical period can be expressed as: ; in, Indicates the conductivity fluctuation similarity index between the current period and the period in the historical period. Indicates the conductivity characteristic value of the current period, Indicates the historical period The conductivity characteristic value of each period, Indicates the absolute value sign.

[0031] Indicates the difference between the conductivity characteristic value of the current period and the conductivity characteristic value of the period in the historical period. The larger the value, the greater the difference between the conductivity characteristic values ​​of the two periods. In this embodiment, 0.01 is added to the denominator of the calculation formula of the conductivity fluctuation similarity index to prevent the denominator from being 0. In specific applications, the implementer can set it according to specific circumstances. The smaller the difference between the conductivity characteristic values ​​of the two time periods, the more similar the conductivity is in the two time periods, that is, the greater the conductivity fluctuation similarity index between the current time period and the time period in the historical cycle.

[0032] For any historical period, the period corresponding to the maximum conductivity fluctuation similarity index between the historical period and the current period is considered the matching period of the current period in the historical period. This method can be used to select the matching period of the current period in each historical period.

[0033] Natural seawater contains scale, colloids, microorganisms, etc. When they adhere to the electrode surface of the conductivity sensor, there is a possibility that the measurement sensitivity of the conductivity sensor will be interfered with to varying degrees. In addition, the high-salt and high-pressure environment may cause corrosion of the conductivity sensor electrodes, resulting in errors in the actual detection values. Therefore, it is necessary to make real-time corrections to the measured values ​​of the conductivity sensor based on the fluctuations in the difference between the measured data and the predicted values.

[0034] The data measured by different conductivity sensors are somewhat correlated. For example, fluctuations in the salinity of natural seawater (fluctuations in the data measured by the conductivity sensor at the raw seawater inlet) often affect the salt load in the entire desalination system, causing correlated fluctuations in the conductivity values ​​on both sides of the RO module.

[0035] For either sensor: Curve fitting is performed on the conductivity at all times within each cycle to obtain a conductivity curve for each cycle. Curve fitting is a conventional technique and will not be described in detail here. The DTW distance between the conductivity curve for each historical cycle and the conductivity curve for the current cycle is calculated. The DTW distance calculation method is conventional and will not be described in detail here.

[0036] Calculate the average value of the conductivity at all times within each matching period and record this average value as the first average value. Record the product of the DTW distance between the conductivity curve of the period in which each matching period falls and the conductivity curve of the current period and the corresponding first average value as the first product corresponding to each matching period. The average value of the first products corresponding to all matching periods is used as the conductivity prediction mean value for the current period.

[0037] The difference between the conductivity at each moment in the current time period and the predicted conductivity mean is calculated, and this difference is recorded as a first difference. The average of the first differences corresponding to all moments in the current time period is calculated. The sum of the conductivity at each moment in the current time period and the average of the first differences is used as the predicted value for each moment in the current time period. The difference between the conductivity at each moment in the current time period and the corresponding predicted value is used as a difference index for each moment. If the difference index for each moment is too large, and the addition of the measured data at the current moment causes a sudden change in the degree of correlation between the sensor and the other conductivity sensors in that period, there is a high probability that the data measured by the sensor at the current moment contains errors.

[0038] The error factor of the sensor at the current moment is obtained based on the DTW distances between the conductivity curves of the sensor and all other sensors in the current period and the difference index at the current moment. Specifically, the average DTW distances between the conductivity curves of the sensor and all other sensors in the current period are calculated. The ratio of the difference index at the current moment to the average difference index at all times in the current period is calculated and recorded as a first ratio. The larger the first ratio, the greater the deviation of the predicted conductivity at the current moment from that at other times in the period. The product of the average DTW distances between the conductivity curves of the sensor and all other sensors in the current period and the first ratio is determined as the error factor of the sensor in the current period. The larger the error factor, the greater the possibility of sensor error, the more necessary it is to adjust, and the greater the reduction in the Kalman filter gain. The difference between the constant 1 and the error factor is used as the first adjustment coefficient. The product of the first adjustment coefficient and the initial gain of the Kalman filter when denoising the conductivity is used as the adjusted Kalman filter gain.

[0039] After determining the adjusted Kalman filter gain, the conductivity collected by the sensor is filtered using the Kalman filter algorithm, and the conductivity obtained after filtering is recorded as the corrected conductivity. The Kalman filter algorithm is a prior art and will not be described in detail here.

[0040] Step S3, based on the conductivity and corrected conductivity of the sensors on the water inlet and water outlet sides of the RO component, as well as the water outlet pressure, the contamination degree of the RO component at each moment is obtained; combined with the contamination degree and the level of the RO component, the salt measurement interference index corresponding to the RO component is determined.

[0041] In a seawater desalination system, the RO component allows fresh water to pass through a semi-permeable membrane to produce water by intercepting salt. Water molecules are pushed through the RO component by applying a pressure higher than the osmotic pressure.

[0042] Under normal circumstances, when the desalination capacity of the RO component is good, the conductivity of the water production side of the RO component should be much lower than that of the water inlet side, and the pressure difference measured on both sides is small. When pollutants accumulate in the RO component, colloids, microorganisms, salt scale and other foulants in the raw seawater form a dense layer on the membrane surface, hindering ion retention. At this time, the desalination capacity of the RO component is weakened, resulting in a high salinity of the produced water. There may even be fouling that causes the backflow of concentrated water or local concentration, indirectly pushing up the conductivity value of the water inlet end of the RO component.

[0043] There may be multiple RO components in the seawater desalination system. This embodiment takes a single RO component as an example and analyzes the fouling and blockage of the RO component in its current state based on the corrected conductivity data.

[0044] Combined with the above analysis, when the RO component is highly contaminated, the membrane surface contamination will cause local salt concentration on the concentrate side or backflow to the water inlet, making the corrected conductivity of the water inlet side higher; when the contamination level is high, the desalination capacity of the RO membrane is disturbed, and it cannot effectively retain salt, resulting in a higher conductivity on the water production side; when the contamination level is high, the membrane pores are blocked, resulting in increased water flow resistance, which in turn increases the pressure on the water outlet side.

[0045] At a certain moment, the conductivity of the inlet and product water sides of the RO component is measured to be higher than the conductivity of the original seawater inlet, and the difference in conductivity between the two sides is small. When the outlet water pressure measured by the product water is higher, the degree of contamination of the RO component at that moment is relatively high.

[0046] For any moment: The ratio of the corrected conductivity of the RO component water inlet sensor at that moment to the conductivity of the RO component water inlet sensor at that moment (the initially collected conductivity) is calculated, and this ratio is recorded as the second ratio. Next, the ratio of the corrected conductivity of the RO component water outlet sensor to the conductivity of the RO component water outlet sensor is calculated, and this ratio is recorded as the third ratio.

[0047] The contamination level of the RO component at any moment is obtained based on the product of the second ratio and the third ratio, the difference between the second ratio and the third ratio, and the outlet water pressure. The product of the second ratio and the third ratio and the outlet water pressure are both positively correlated with the contamination level, and the difference between the second ratio and the third ratio is negatively correlated with the contamination level.

[0048] Among them, a positive correlation relationship indicates that the dependent variable will increase as the independent variable increases, and the dependent variable will decrease as the independent variable decreases. It can be an additive relationship, a multiplicative relationship, etc., which is determined by actual application; a negative correlation relationship indicates that the dependent variable will decrease as the independent variable increases, and the dependent variable will increase as the independent variable decreases. It can be a subtractive relationship, a division relationship, etc., which is determined by actual application.

[0049] In this embodiment, a specific calculation formula for the pollution degree is given. The pollution degree at the i-th moment can be expressed as: ; in, represents the pollution level at the i-th moment, represents the ratio between the corrected conductivity of the sensor on the water inlet side of the RO component at the i-th moment and the conductivity of the sensor on the water inlet side of the RO component at the i-th moment, that is, the second ratio; represents the ratio between the corrected conductivity of the sensor on the outlet side of the RO component at the i-th moment and the conductivity of the sensor on the outlet side of the RO component at the i-th moment, that is, the third ratio; Indicates the outlet pressure of the RO component at the i-th moment, Represents the normalization function.

[0050] In this embodiment, 0.01 is added to the denominator of the calculation formula for the pollution degree in order to prevent the denominator from being 0. In specific applications, the implementer may set it according to specific circumstances. The smaller the value, the smaller the difference in conductivity between the inlet and product sides of the RO module. The larger the second ratio, the larger the third ratio, and the smaller the difference between the second and third ratios, the greater the degree of contamination at the i-th moment.

[0051] By adopting the above method, the pollution degree at each moment can be obtained.

[0052] The contamination level of RO components can interfere with the accuracy of salinity measurements. For example, contaminant accumulation in RO components can cause localized blockage of the water flow path, exacerbating concentration polarization and significantly increasing the salt concentration on the RO component surface compared to the main fluid. This can lead to falsely high readings on the conductivity sensor on the product water side. Furthermore, contaminants on RO components can cause non-steady-state changes in salt migration (e.g., sudden increases in conductivity), thus interfering with the accuracy of salinity measurements. Therefore, it is necessary to analyze the degree of interference with current salinity measurements based on the changing trend of RO component contamination.

[0053] During the desalination process, RO components are usually flushed to reduce the extent to which they are affected by pollutants and maintain the performance of the RO components.

[0054] If the contamination level of the current RO component is high after the most recent RO component flushing, and the current contamination level has increased significantly compared to the most recent RO component flushing, and the component has a low stage in the current seawater desalination system (severe contamination of low-stage components will cause the water quality of subsequent stages to deteriorate), and the time since the most recent RO component flushing is short, then in the current state, the RO membrane filtration performance deteriorates faster, and the performance of the RO component cannot be maintained by flushing, which will cause greater interference to the salt measurement on both sides.

[0055] Based on the above characteristics, the difference between the current contamination level and the contamination level after the previous flush is used as the contamination level growth amplitude. The salinity interference index corresponding to the RO component is determined based on the current contamination level after the previous flush, the contamination level growth amplitude, the component level, and the time interval between the current and previous flushes. Specifically, the product of the current contamination level after the previous flush and the contamination level growth amplitude is calculated and recorded as the second product. The product of the component level and the time interval between the current and previous flushes is recorded as the third product. The ratio of the second and third products is determined as the salinity interference index corresponding to the RO component. It should be noted that the contamination level after the previous flush is the contamination level immediately after the previous flush.

[0056] Thus, this embodiment has determined the salt measurement interference index corresponding to the RO component.

[0057] Step S4: adjusting the Kalman filter gain during salinity denoising based on the salt measurement interference index, and filtering the salinity to obtain a corrected salinity.

[0058] When the pollution growth trend of a certain RO component at the current moment interferes greatly with the salinity measurement, the correction intensity of its salinity measurement should be increased to reduce the error accumulation of salinity measurement and capture the salinity fluctuations of the actual water quality.

[0059] Taking a single RO component as an example, the greater the interference of the current pollution growth trend on the salinity measurement on both sides of the component, the more necessary it is to measure the salinity on both sides and correct the salinity measurement value based on Kalman filtering. The greater the correction strength of the salinity measurement required on both sides of the RO component, the smaller the corresponding Kalman filter gain should be.

[0060] Specifically, the difference between the constant 1 and the salt measurement interference index is calculated and recorded as the second difference; the product of the second difference and the initial gain of the Kalman filter when denoising the salt measurement interference index is taken as the adjusted Kalman filter gain.

[0061] After determining the adjusted Kalman filter gain, the initially collected salinity is filtered using the Kalman filter algorithm, and the salinity obtained after filtering is recorded as the corrected conductivity. The Kalman filter algorithm is a prior art and will not be described in detail here.

[0062] At this point, the salinity of seawater has been measured using the method provided in this embodiment.

[0063] This embodiment monitors the conductivity and outlet pressure of each sensor on both sides of the RO component during the seawater desalination process. Based on the similarity in conductivity variation characteristics between each period in the historical cycle and the current period, and the difference in conductivity fluctuation between the historical period and the current period, a matching period for the current period is selected. The Kalman filter gain is adjusted based on the conductivity at all times in the current period and the difference in conductivity fluctuation between the current period and the period in which it matches the matching period. The conductivity collected by the sensor is then filtered. The contamination level of the RO component after flushing is evaluated based on the conductivity and corrected conductivity of the sensors on the inlet and outlet sides of the RO component, as well as the outlet pressure. The salinity measurement interference index corresponding to the RO component is determined based on the level of the RO component. The Kalman filter gain is then adjusted during salinity denoising, thereby achieving filtering of the salinity data and improving the accuracy of salinity measurement.

[0064] An embodiment of a water quality salinity measurement and correction system for seawater desalination: See Figure 2 , which shows a structural block diagram of a water quality salinity measurement and correction system for seawater desalination provided by an embodiment of the present invention. The system may include a data acquisition module, a first correction module, a calculation module and a second correction module.

[0065] The data acquisition module is used to obtain the conductivity, outlet pressure, and salinity of each sensor on both sides of the RO component during the desalination process. The desalination process includes multiple historical cycles and a current cycle. Each cycle contains multiple time periods, and the current time period is the time period at the current moment. A first correction module is configured to, for each sensor, select a matching period for the current period within each historical period based on the similarity between the conductivity change characteristics of each period within the historical period and the current period, and the conductivity fluctuation difference between the historical period and the current period; adjust the Kalman filter gain during conductivity denoising based on the conductivity at all times within the current period and the conductivity fluctuation difference between the current period and the period in which the matching period lies, and perform conductivity filtering to obtain a corrected conductivity; a calculation module for obtaining the contamination level of the RO component at each moment based on the conductivity and corrected conductivity of the sensors at the inlet and outlet sides of the RO component, as well as the outlet pressure; and determining the salt measurement interference index corresponding to the RO component based on the contamination level and the level of the RO component; The second correction module is used to adjust the Kalman filter gain during salinity denoising based on the salt measurement interference index, and to filter the salinity to obtain the corrected salinity.

[0066] It should be understood that Figure 2 The block diagram of a system for measuring and correcting salinity in seawater desalination water and its modules can be implemented in various ways. For example, in some embodiments, the system and its modules can be implemented using hardware, software, or a combination of software and hardware. The hardware portion can be implemented using dedicated logic, while the software portion can be stored in memory and executed by an appropriate instruction execution system, such as a microprocessor or specially designed hardware. Those skilled in the art will appreciate that the above-described methods and systems can be implemented using computer-executable instructions and / or contained in processor control code, such as provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The systems and their modules described herein can be implemented not only using hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips or transistors, or programmable hardware devices such as field-programmable gate arrays or programmable logic devices, but can also be implemented using software executed by various types of processors, or a combination of such hardware circuits and software (e.g., firmware).

[0067] For more details about the above modules, please refer to other places in this manual and will not be repeated here.

[0068] In other embodiments, a device for measuring and correcting the salinity of water used in seawater desalination is provided, comprising a memory and a processor. The memory is configured to store executable program code, and the processor is configured to retrieve and execute the executable program code from the memory, causing the device to perform the aforementioned method for measuring and correcting the salinity of water used in seawater desalination. The device may specifically be a chip, component, or module, and the chip may include a connected processor and memory. The memory is configured to store instructions, and when the processor retrieves and executes the instructions, the chip can perform the aforementioned method for measuring and correcting the salinity of water used in seawater desalination.

[0069] In other embodiments, a computer program product is also provided. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned related steps to implement the method for measuring and correcting the salinity of water quality for seawater desalination provided in the above embodiment.

[0070] In other embodiments, a computer-readable storage medium is also provided, which stores computer program code. When the computer program code is run on a computer, the computer executes the above-mentioned related method steps to implement a method for measuring and correcting the salinity of water quality for seawater desalination provided in the above embodiment.

[0071] Among them, the provided systems, electronic devices, computer program products, and computer-readable storage media are all used to execute the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0072] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring and correcting the salinity of water used in seawater desalination, characterized in that: The method comprises the following steps: Obtain the conductivity, outlet pressure, and salinity of each sensor on both sides of the RO component during the desalination process. The desalination process includes multiple historical cycles and a current cycle. Each cycle contains multiple time periods, and the current time period is the time period at the current moment. For each sensor, based on the similarity of conductivity change characteristics between each period in the historical cycle and the current period, and the conductivity fluctuation difference between the historical period and the current period, the matching period of the current period in each historical cycle is selected. The Kalman filter gain is adjusted during conductivity denoising based on the conductivity at all times in the current period and the conductivity fluctuation difference between the current period and the period in which the matching period belongs. The conductivity filter is then used to obtain the corrected conductivity. The contamination level of the RO component at each moment is determined based on the conductivity and corrected conductivity of the sensors at the inlet and outlet sides of the RO component, as well as the outlet pressure. The salt measurement interference index corresponding to the RO component is determined based on the contamination level and the level of the RO component. The Kalman filter gain is adjusted during salinity denoising based on the salt measurement interference index, and the salinity is filtered to obtain the corrected salinity.

2. The method for measuring and correcting salinity of water used in seawater desalination according to claim 1, characterized in that: The method of screening the matching period of the current period in each historical period based on the similarity of the conductivity change characteristics between each period in the historical period and the current period and the conductivity fluctuation difference between the historical period and the current period includes: For any period: The ratio between the range of the conductivity at all times in any period and the duration of any period is recorded as the conductivity characteristic value of any period; According to the difference between the conductivity characteristic value of the current period and each period in the historical period, the conductivity fluctuation similarity index of the current period and each period in the historical period is obtained; For any historical period: the period corresponding to the maximum value of the conductivity fluctuation similarity index in the historical period and the current period is used as the matching period of the current period in the historical period.

3. The method for measuring and correcting salinity of water used in seawater desalination according to claim 1, characterized in that: The Kalman filter gain for conductivity denoising is adjusted by combining the conductivity at all moments in the current period and the conductivity fluctuation difference between the current period and the period in which the current period matches the current period, including: For either sensor: Calculate the DTW distance between the conductivity curve of each historical period and the conductivity curve of the current period respectively, where the conductivity curve of each period is obtained by curve fitting the conductivity at all moments in the period; Calculate the first average value of the conductivity at all times within each matching period respectively; multiply the DTW distance between the conductivity curve of the period in which each matching period falls and the conductivity curve of the current period by the corresponding first average value, and record it as the first product corresponding to each matching period; and take the average value of the first products corresponding to all matching periods as the conductivity prediction mean value for the current period; Calculating the difference between the conductivity at each moment in the current time period and the predicted conductivity mean value as a first difference value corresponding to each moment in the current time period; calculating the average value of the first difference values ​​corresponding to all moments in the current time period; and taking the sum of the conductivity at each moment in the current time period and the average value of the first difference values ​​as the predicted value at each moment in the current time period; The difference between the conductivity at each moment in the current period and the corresponding predicted value is used as the difference index at each moment; Obtaining an error factor of the any one sensor at a current moment according to the DTW distance between the conductivity curves of the any one sensor and each of the remaining sensors in the current cycle and the difference index; The error factor is used to adjust the Kalman filter gain during conductivity denoising.

4. The method for measuring and correcting salinity of water used in seawater desalination according to claim 3, characterized in that: Obtaining the error factor of any one sensor at a current moment according to the DTW distance between the conductivity curves of any one sensor and each of the remaining sensors in the current cycle and the difference index includes: Calculating an average of the DTW distances between the conductivity curves of any one sensor and all other sensors in the current cycle; Calculate a first ratio between the difference index at the current moment and the average difference index of all moments in the current period; The product of the average value of the DTW distance and the first ratio is determined as the error factor of the any sensor in the current period.

5. The method for measuring and correcting salinity of water used in seawater desalination according to claim 3, characterized in that: The step of adjusting the Kalman filter gain during conductivity denoising by using the error factor includes: The difference between the constant 1 and the error factor is used as a first adjustment coefficient; The product of the first adjustment coefficient and the initial gain of the Kalman filter when denoising the conductivity is used as the adjusted Kalman filter gain.

6. The method for measuring and correcting salinity of water used in seawater desalination according to claim 1, characterized in that: The contamination degree of the RO component at each moment is obtained based on the conductivity and the corrected conductivity of the sensors at the water inlet and water outlet of the RO component, as well as the water outlet pressure, including: For any moment: Calculating a second ratio between the corrected conductivity of the sensor on the water inlet side of the RO component and the corresponding conductivity at any moment, and a third ratio between the corrected conductivity of the sensor on the water outlet side of the RO component and the corresponding conductivity; The contamination level of the RO component at any moment is obtained based on the product of the second ratio and the third ratio, the difference between the second ratio and the third ratio, and the outlet water pressure. The product of the second ratio and the third ratio and the outlet water pressure are both positively correlated with the contamination level, and the difference between the second ratio and the third ratio is negatively correlated with the contamination level.

7. The method for measuring and correcting salinity of water used in seawater desalination according to claim 1, characterized in that: Determining the salt measurement interference index corresponding to the RO component based on the pollution degree and the level of the RO component includes: The difference between the pollution level at the current moment and the pollution level after the previous flushing at the current moment is taken as the pollution level growth amplitude; The salt measurement interference index corresponding to the RO component is obtained according to the pollution degree after the previous flushing at the current moment, the pollution degree growth amplitude, the component level and the time interval between the current moment and the previous flushing at the current moment.

8. The method for measuring and correcting salinity of water used in seawater desalination according to claim 7, characterized in that: The salt measurement interference index corresponding to the RO component is obtained based on the pollution degree after the previous flushing at the current moment, the pollution degree growth amplitude, the component level, and the time interval between the current moment and the previous flushing at the current moment, including: Calculating a second product of the contamination level after the previous flush at the current moment and the magnitude of the contamination level increase, and a third product of the level of the RO component and the time interval between the current moment and the previous flush at the current moment; The ratio of the second product to the third product is determined as the salt measurement interference index corresponding to the RO component.

9. The method for measuring and correcting salinity of water used in seawater desalination according to claim 1, characterized in that: The method of adjusting the Kalman filter gain during salinity denoising based on the salt measurement interference index includes: calculating a second difference between the constant 1 and the salt determination interference index; The product of the second difference and the initial gain of the Kalman filter when denoising the salt measurement interference index is used as the adjusted Kalman filter gain.

10. A system for measuring and correcting salinity of water used in seawater desalination, the system being capable of implementing the method according to claim 1, characterized in that: The system comprises: The data acquisition module is used to obtain the conductivity, outlet pressure, and salinity of each sensor on both sides of the RO component during the desalination process. The desalination process includes multiple historical cycles and the current cycle. Each cycle contains multiple time periods, and the current time period is the time period at the current moment. A first correction module is configured to, for each sensor, select a matching period for the current period within each historical period based on the similarity between the conductivity change characteristics of each period within the historical period and the current period, and the conductivity fluctuation difference between the historical period and the current period; adjust the Kalman filter gain during conductivity denoising based on the conductivity at all times within the current period and the conductivity fluctuation difference between the current period and the period in which the matching period lies, and perform conductivity filtering to obtain a corrected conductivity; a calculation module for obtaining the contamination level of the RO component at each moment based on the conductivity and corrected conductivity of the sensors at the inlet and outlet sides of the RO component, as well as the outlet pressure; and determining the salt measurement interference index corresponding to the RO component based on the contamination level and the level of the RO component; The second correction module is used to adjust the Kalman filter gain during salinity denoising based on the salt measurement interference index, and to filter the salinity to obtain the corrected salinity.

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