A method and system for detecting the precipitation rate of inorganic salts in water, an electronic device, and a storage medium

Abstract

The present invention discloses a detection method and detection system, electronic device and storage medium for the precipitation speed of inorganic salts in water, wherein the detection method comprises the following steps: S1: obtaining the type of inorganic salts precipitated in the water to be tested, one of the inorganic carbon methyl orange alkalinity (Cmalk), pH value and total dissolved inorganic carbon (DIC) in the water to be tested, and the element and initial content of the target inorganic salt contributing to the alkalinity of non-inorganic carbon methyl orange; S2: continuously detecting the change value of the carbon dioxide concentration (CO2w) or the gas phase carbon dioxide concentration (PCO2) balanced with it in the water to be tested over time under a closed constant temperature and constant pressure environment; S3: obtaining the precipitation amount of the target inorganic salt according to the data obtained in step S1 and step S2; S4: obtaining the precipitation speed of the target inorganic salt according to the precipitation amount obtained in step S3. A detection method for the precipitation speed of inorganic salts in water with less manual intervention, low detection limit and high precision is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method and system for detecting the precipitation rate of inorganic salts in water, an electronic device, and a storage medium. Background Art

[0002] Scale is defined as an unwanted layer of hard salt formed on the surface; these surfaces can be the surfaces of heat exchangers, water pipes or containers, pores in rocks, membranes and membrane pores; excessive scale will cause a decrease in heat exchange efficiency, an increase in delivery pressure and energy consumption, a decrease in oil field production efficiency and damage to oil field related facilities, a decrease in reverse osmosis membrane efficiency and damage to facilities; the main chemical methods used to control scale include adjusting the supersaturation of these scale-forming inorganic salts, adding scale inhibitors that inhibit the precipitation of inorganic salts, etc.; the most commonly used mechanism for controlling scale is to control the crystallization reaction of these salts, that is, to control the amount and rate of precipitation of these salts from water. After judging the main scale type and calculating the supersaturation through water quality parameters and application conditions (such as temperature) combined with the inorganic salt solubility product constant and designing a scheme to adjust the crystallization reaction characteristics of the target inorganic salt, the scheme needs to be verified in the laboratory and then put into practical use; one of the main contents of laboratory verification and practical application is to detect the amount and speed of precipitation of the target inorganic salt from water. The process of laboratory detection of the amount and speed of precipitation of the target inorganic salt from water is referred to as process 1, and the process of detecting the amount and speed of precipitation of the inorganic salt from water in field application is referred to as process 2.

[0003] The prior art in process 1 includes static scale inhibition methods, such as the calcium carbonate precipitation method disclosed in GB / T16632-2008 Determination of scale inhibition performance of water treatment agents; the bubbling method disclosed in HG / T2024-2009 Determination of scale inhibition performance of water treatment agents; the limiting carbonate method disclosed in HG / T4541-2013 Determination of scale inhibition performance of water treatment agents, the turbidity method disclosed in V. Tantayakom at all., Scale inhibition study by turbidity measurement, Journal of Colloid and Interface Science 284 (2005) 57–65., as well as conductivity method, critical pH method, pH displacement method, dynamic simulation evaluation method, etc.

[0004] The existing technologies in process 2 include calculating the ratio of ions that are difficult to precipitate in water, such as potassium ions, sodium ions, and chloride ions, to ions that may precipitate, and also attempting to calculate the precipitation amount and speed of sparingly soluble salts through the mass balance of water volume and ion concentration in water; adding two fluorescent substances in a certain proportion to water, one of which is synthesized on the scale inhibitor, and the other fluorescent substance is considered not to be consumed in water, and by monitoring the difference between the two fluorescent substances, the consumption of the scale inhibitor is reflected, and it is considered that the precipitation of sparingly soluble salts will consume the scale inhibitor, thereby indirectly reflecting the precipitation amount and speed of sparingly soluble salts, hereinafter referred to as 3D TRASAR TM Method; monitoring heat exchanger method, etc.

[0005] In process 1:

[0006] The static scale inhibition method calculates the scale inhibition rate by measuring the concentration of residual dissolved ions after the target inorganic salts are precipitated after 10 hours at constant temperature in water samples with and without scale inhibitors (for example, for calcium carbonate scale, calcium ions or alkalinity can be detected; for calcium phosphate scale, phosphate concentration can be monitored). This type of method is restricted by the repeatability of prepared water, sampling method, and detection limit of target ions (for example, in the EDTA titration method for determination of calcium in water quality in GB7476-87, the absolute value of the analytical error of calcium ions is ±5mg / L in terms of calcium ions. If converted to CaCO3, it is ±12.5mg / L). When designing the experiment, the initial ionic strength of the target sediment is often prepared to be much higher than the actual water quality, so that the experimental results can only qualitatively reflect the pros and cons of the control scheme. In addition, the test cycle is long and there is much manual intervention.

[0007] The bubbling method is mainly used to evaluate the scale inhibition effect of calcium carbonate scale. Prepare a test solution containing calcium bicarbonate and scale inhibitor, heat and aerate the test solution, and after 6 hours, cool the water sample to room temperature and filter it. Then use EDTA (ethylenediaminetetraacetic acid) titration to determine the calcium ion concentration in the water. The higher the calcium ion concentration, the better the performance of the scale inhibitor. Although this method shortens the test cycle by bubbling, it is similar to the static scale inhibition method. Due to the restriction of the target ion detection limit, the initial ion strength of the target sediment is prepared to be much higher than the actual water quality, so that the experimental results can only qualitatively reflect the advantages and disadvantages of the control scheme.

[0008] The limiting carbonate method uses field water or prepared water simulating field water quality and scale inhibitor to prepare the test solution. Under heating and aeration conditions, it is evaporated and concentrated. Samples are taken every 4 hours to analyze and determine the total alkalinity, calcium ion concentration and chloride ion concentration. The sum of the total alkalinity and calcium ion concentration (both in terms of calcium carbonate) is defined as the carbonate value. As the water evaporates and concentrates, when calcium carbonate begins to precipitate in the water, the ionic calcium ions and total alkalinity decrease. Therefore, over time, the carbonate value will decrease after reaching a maximum point. This maximum value is defined as the limiting carbonate value. The larger the limiting carbonate value, the better the performance of the scale inhibitor. It can be seen from the requirement in the standard that the absolute difference of the parallel determination results of the carbonate value is not greater than 10 mg / L (in terms of calcium carbonate) that the resolution of the limiting carbonate value of this standard is less than 10 mg / L (in terms of calcium carbonate). In addition to the limited resolution, this method also has the defects of large workload of manual analysis.

[0009] Turbidimetric methods all use the principle that when insoluble inorganic salts precipitate from water, the turbidity of the water increases due to the generation of suspended particles of insoluble substances. By measuring the turbidity, the ability of insoluble inorganic salts to precipitate from the test water is reflected. This type of method uses different methods in experimental design and data interpretation and calculation of turbidity (or transmittance). However, the basic principle is to use the change in turbidity as the basis for the precipitation and concentration calculation of inorganic salts. The measurement of turbidity is based on the principle of optics. In these tests, there is an isolation surface between the water to be tested and the light. In order to control the difference between the turbidity actually detected and the turbidity generated in the real water caused by the deposition on the isolation surface, these methods inevitably require frequent and strict cleaning of the optical circuit. Moreover, at low inorganic salt precipitation rates, turbidity has very limited resolution. For example, Chen Quan, Xiong Rihua, Huo Weidong. Method for determining the dosage of calcium sulfate antiscalant using turbidity [J]. Guangdong Chemical Industry, 2016, 43(04): 46+45. When the calcium sulfate supersaturation is 20, the turbidity difference (the difference between the turbidity at 1.5 hours and the initial turbidity) of a scale inhibitor at an addition amount of 0, 2, 4, 6, 8, 10 mg / L after 1.5 hours is 0.49, 0.42, 0.34, 0.13, 0.14, 0.13 NTU. It can be seen that at this saturation and without adding scale inhibitor, the turbidity change caused by calcium sulfate precipitation is only 0.49 NTU. It can also be seen from the data that at low saturation, this method cannot distinguish the performance difference of calcium sulfate precipitation from water at scale inhibitor addition amounts of 6, 8, 10 mg / L. Therefore, the precipitation rate of insoluble salts detected based on turbidity has problems such as frequent cleaning of the optical detection circuit, low resolution under low supersaturation conditions, and interference from color and other suspended matter when used in actual water on site.

[0010] The conductivity method evaluates the scale inhibition performance of the scale inhibitor by measuring the critical supersaturation value calculated from the mutation point of the conductivity when the inorganic salt in the test solution precipitates. The main disadvantage of this method is that the critical supersaturation value can only qualitatively compare the performance of different scale inhibitors. The precipitation of inorganic salts in water will inevitably deposit on the conductivity electrode, so the electrode needs to be cleaned and maintained regularly.

[0011] The critical pH method is mainly based on the crystal growth theory, which believes that for slightly soluble salts such as calcium carbonate, a certain degree of supersaturation must be exceeded before crystals can precipitate. When crystals precipitate, the pH value corresponding to the supersaturation is called the critical pH value. When the actual pH value exceeds the critical pH value, crystals will precipitate. When it is lower than the critical pH value, crystals will not precipitate. This method is often used in the laboratory to qualitatively evaluate the performance of scale inhibitors. The absolute error of the measured critical pH value is ±0.1. This method cannot quantitatively determine the precipitation rate of inorganic salts in water. Moreover, the pH electrode is easily adsorbed by the precipitated crystals under this test environment, and the pH electrode needs to be cleaned and calibrated regularly. The stability of the pH electrode at high temperature also restricts the measurement temperature of this method.

[0012] The pH shift method uses the difference between the initial pH of the supersaturated solution of calcium bicarbonate and the stable pH after a certain period of time after adding a quantitative scale inhibitor to evaluate the scale inhibition performance of the scale inhibitor on calcium carbonate. The shift method improves the resolution of the measurement at low concentrations of the scale inhibitor. However, according to its principle, similar to the critical pH method, there are limitations in the stability of the pH electrode and the test temperature.

[0013] The above methods all characterize the amount of inorganic salts precipitated from water or the critical point where precipitation begins by using some chemical or physical changes in the test solution at a certain supersaturation. The static scale inhibition and bubbling methods use the change in the concentration of scaling inorganic salt ions to calculate the scale inhibition rate (precipitation inhibition rate); the limiting carbonate method continuously increases the supersaturation during the test and regularly measures the concentration of related ions. When the concentration of scaling inorganic salt ions is detected to decrease, it is considered to be the critical point for the precipitation of inorganic salts from water. For calcium carbonate scale, the sum of the total alkalinity and calcium ion concentration (both in terms of calcium carbonate) at this time is defined as the limiting carbonate value; the conductivity method, critical pH method, and turbidity method measure the jump points of conductivity, pH, and turbidity respectively, calculate the supersaturation at the jump point, and use this as the basis to calculate the scale inhibition rate (precipitation inhibition rate), limiting carbonate, critical supersaturation ratio, and critical supersaturation value.

[0014] In process 2:

[0015] The precipitation rate of sparingly soluble inorganic salts in water is calculated by the ratio of ions that are difficult to precipitate in water, such as potassium ions, sodium ions, and chloride ions, to ions that may precipitate, or by trying to calculate the precipitation rate of sparingly soluble inorganic salts in water through the mass balance of water volume and ion concentration in water. However, this method has great limitations because the ratio of ions that are difficult to precipitate to ions that may precipitate in the original water itself has different stability. TM In this method, the fluorescence detection is sometimes interfered by some substances, such as the cationic surfactants commonly used in water treatment, which limits the application of this method. The heat exchanger monitoring method characterizes the degree of deposition by the weight of surface deposits or the thermal resistance of deposit fouling. In practical applications, the deposition rate is controlled to be very low, such as 20 mg / cm 2 / month, resulting in a long test cycle, and the test results only represent the average value within the test cycle. If the dirt thermal resistance is found to increase sharply during the test, the system has already produced serious and unacceptable deposition. The hysteresis can only be used to count and summarize the treatment effect afterwards.

[0016] Theoretically, by measuring the concentration change of target inorganic ions in water samples after a certain period of constant temperature, the rate at which these inorganic substances precipitate from water can be calculated. However, this method cannot achieve the desired result because the precipitation rate that must be controlled in actual application environments is very low and the concentration analysis of these ions in the prior art has limited precision and accuracy.

[0017] The capillary method in the dynamic simulation test method detects the pressure difference change of the test liquid in the two sections of the capillary under constant temperature and pressure to reflect the degree of adsorption of inorganic salts on the capillary after precipitation. This method requires strict control of the capillary flow rate, so a constant flow pump with high precision but low tolerance to suspended matter in water is used. This limits its practical application on site. Summary of the invention

[0018] The purpose of the present invention is to provide a method for detecting the precipitation amount and precipitation speed of sparingly soluble inorganic salts in water containing inorganic carbon methyl orange alkalinity which will cause alkalinity changes after precipitation, with less manual intervention, low detection limit and high precision, as well as a detection system, electronic equipment and storage medium.

[0019] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is to provide a method for detecting the precipitation rate of inorganic salts in water, comprising the following steps: S1: obtaining the type of inorganic salt precipitated in the water to be tested, one of the inorganic carbon methyl orange alkalinity (Cmalk), pH value, total dissolved inorganic carbon (DIC), total dissolved solid content (TDS), and the elements and contents of the target inorganic salt that contribute to the alkalinity of non-inorganic carbon methyl orange; S2: continuously detecting the change value of the carbon dioxide concentration (CO2w) or the gas phase carbon dioxide concentration (PCO2) in equilibrium with it in the water to be tested over time in a closed constant temperature and pressure environment; S3: obtaining the precipitation amount of the target inorganic salt according to the data obtained in step S1 and step S2; S4: obtaining the precipitation rate of the target inorganic salt according to the precipitation amount obtained in step S3 and the time in S2.

[0020] Preferably, in step S1, the other two of the inorganic carbon methyl orange alkalinity (Cmalk), pH value, and total dissolved inorganic carbon (DIC) in water are calculated according to the following formula:

[0021] DIC=CO2w×(1+k'1 / (H + )+k'1×k'2 / (H + )^2,----(1)

[0022] Cmalk=50000×CO2w×(k'1 / (H + )+2k'1×k'2 / (H + )^2),----(2)

[0023] pH = -log(H + )----(3)

[0024] Where DIC is the total dissolved inorganic carbon concentration in water (mol / L), CO2w ​​is the carbon dioxide concentration in the water to be tested (mol / L), Cmalk is the alkalinity of inorganic carbon methyl orange in water (mg / L, in terms of calcium carbonate), H + is the hydrogen ion concentration in the water to be tested (mol / L), k'1 is the first-order dissociation constant of carbonic acid, and k'2 is the second-order dissociation constant of carbonic acid.

[0025] Preferably, the target inorganic salt is calcium carbonate, and there are no other ions in the water to be tested that contribute to the alkalinity of non-inorganic carbon methyl orange, and step S3 comprises the following steps:

[0026] S311: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0027] S312: Knowing CO2w(t1) at t1, calculate H at t1 according to formula (5) + (t1), calculate Cmalk(t1) at t1 according to formula (2), calculate DIC(t1) at t1 according to formula (4),

[0028] (DIC(t0)-DIC(t1))×100×1000=(Cmalk(t0)-Cmalk(t1))--(4)

[0029] 2×CO2w(t0)-2×CO2w(t1)=CO2w(t1)×k'1 / H + (t1)-CO2(t0)×k'1 / H + (t0)--(5)

[0030] S313: Calculate the amount of calcium carbonate precipitation according to formula (6)

[0031] Calcium carbonate precipitation amount CaCO3 = (DIC (t0) - DIC (t1)) × 10^5--(6)

[0032] Wherein, the unit of calcium carbonate precipitation amount CaCO3 is mg / L. Preferably, the precipitated inorganic salt is calcium phosphate, and the water to be tested contains non-inorganic carbon methyl orange alkalinity except orthophosphate, and no other ions that contribute to non-inorganic carbon methyl orange alkalinity, and the step S3 comprises the following steps:

[0033] S321: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0034] S322: Given CO2w(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1), calculate Cmalk(t1) at t1 according to formula (2);

[0035] DIC(t0)=DIC(t1)=CO2w(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)--(7)

[0036] S323: Given Tp(t0) at t0, calculate DIP(t0) according to formula (9), calculate Pmalk(t0) according to formulas (10)-(12), calculate DIP(t1) according to formulas (8)-(12), and calculate the amount of calcium phosphate precipitation according to formula (14);

[0037] (DIP(t0)-DIP(t1)) / 2×2×50×1000=Cmalk(t0)+Pmalk(t0)-Cmalk(t1)-Pmalk(t1)---------(8)

[0038] DIP=Tp / 95 / 1000--------------------------------------------------(9)

[0039] Pmalk=(PO4 3- )×2×50000+(HPO4 2- )×1×50000-----------------(10)

[0040] (PO4 3- )=Tp / 95 / 1000×kp1×kp2×kp3 / ((H + )^3+(H + )^2×kp1+(H + )×kp1×kp2+kp1×kp2×kp3)-(11)

[0041] (HPO4 2- )=(PO4 3- )×(H + ) / kp3-----------------------------------------(12) Calcium phosphate precipitation amount Ca3(PO4)2=(DIP(t0)-DIP(t1)) / 2×310×1000-------(14)

[0042] Where Pmalk is the alkalinity of inorganic phosphorus methyl orange in mg / L in terms of calcium carbonate, DIP is the total dissolved inorganic phosphorus concentration in mol / L, Tp is the total dissolved inorganic phosphorus concentration in mg / L in terms of PO4 3- kp1 is the first order ionization constant of phosphoric acid, kp2 is the second order ionization constant of phosphoric acid, kp3 is the third order ionization constant of phosphoric acid; the unit of calcium phosphate precipitation amount Ca3(PO4)2 is mg / L.

[0043] Preferably, the target inorganic salt is magnesium silicate, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate, and step S3 comprises the following steps:

[0044] S331: Given Cmalk(t0) and CO2(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): +(t0) and DIC(t0);

[0045] S332: Given CO2(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1), calculate Cmalk(t1) at t1 according to formula (2),

[0046] DIC(t0)=DIC(t1)=CO2(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)--(7)

[0047] S333: Given Tsi(t0) at t0, calculate DISi(t0) according to formula (16), calculate Simalk(t0) according to formulas (17) and (18), calculate DISi(t1) according to formulas (15)-(18), and calculate the amount of magnesium silicate precipitation according to formula (19);

[0048] (DISi(t0)-DISi(t1))×2×50×1000=Cmalk(t0)+Simalk(t0)-Cmalk(t1)-Simalk(t1)--(15)

[0049] DISi=Tsi / 60 / 1000--(16)

[0050] Simalk=50000×(Si(OH)3O - )--(17)

[0051] (Si(OH)3O - )=DISi / (1+H + / Ksi)--(18)

[0052] Magnesium silicate precipitation amount MgSiO3 = (DISi(t0)-DISi(t1))×2×50×1000--(19)

[0053] Where DISi is the total dissolved inorganic silicon content mol / L, Tsi is the total dissolved inorganic silicon content mg / L, calculated as SiO2, Simalk is the alkalinity of inorganic silicon methyl orange mg / L, calculated as calcium carbonate, Ksi is the dissociation constant of silicic acid; the unit of magnesium silicate precipitation amount MgSiO3 is mg / L.

[0054] Preferably, the target inorganic salt is colloidal silicon, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate, and step S3 comprises the following steps:

[0055] S341: Given Cmalk(t0) and CO2(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0056] S342: Given CO2(t1) and Cmalk(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1), calculate Cmalk(t1) at t1 according to formula (2);

[0057] DIC(t0)=DIC(t1)=CO2(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)--(7)

[0058] S343: Given Tsi(t0) at t0, DISi(t0) is obtained according to formula (16), Simalk(t0) is calculated according to formulas (17) and (18), DISi(t1) is calculated according to formulas (16)-(18) and (20), and the amount of colloidal silica precipitation is calculated according to formula (21).

[0059] (DIsi(t0)-DIsi(t1))×1×50×1000=-(Cmalk(t0)+Simalk(t0))+(Cmalk(t1)+Simalk(t1))--(20)

[0060] DISi=Tsi / 60 / 1000--(16)

[0061] Simalk=50000×(Si(OH)3O - )=50000×DISi / (1+H + / Ksi)--(17)

[0062] (Si(OH)3O - )=DISi / (1+H + / Ksi)--(18)

[0063] Colloidal silica precipitation amount SiO2 = (DISi(t0)-DISi(t1))×1×60×1000--(21)

[0064] The unit of colloidal silicon precipitation amount SiO2 is mg / L.

[0065] Preferably, step S2 includes: detecting the carbon dioxide gas concentration PCO2 in a closed detector, a gas circulation pump and a gas phase carbon dioxide detector are provided in the loop of the closed detector, and the carbon dioxide gas concentration PCO2 is continuously recorded during the detection; and then the carbon dioxide gas concentration PCO2 is converted into the carbon dioxide concentration CO2w ​​in water according to Henry's law, CO2w=Kh×PCO2, Kh is the Henry constant of carbon dioxide.

[0066] To achieve the above objectives, the present invention also provides an electronic device, comprising: a processor; a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned method for detecting the precipitation rate of inorganic salts in water is implemented.

[0067] To achieve the above object, the present invention also provides a computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for detecting the precipitation rate of inorganic salts in water is implemented.

[0068] To achieve the above-mentioned purpose, the present invention also provides a detection system for the precipitation rate of inorganic salts in water, including a closed detector for detecting the concentration of carbon dioxide and the above-mentioned electronic device, wherein the electronic device also includes an input-output module, and the output end of the closed detector is signal-connected to the input-output module of the electronic device.

[0069] Furthermore, the closed detector includes a test container, a carbon dioxide detector, a first constant temperature heating unit and a gas circulation pump. The water to be tested is placed in the test container, the inlet of the carbon dioxide detector is connected to the test container, and the outlet of the carbon dioxide detector is connected to the test container through the gas circulation pump to form a pipeline loop for the circulation of carbon dioxide. The first constant temperature heating unit is arranged on the test container to control the temperature of the test water to be in a constant temperature state.

[0070] The present invention has the following beneficial effects compared with the prior art: the detection method and detection system, electronic device, and storage medium of the inorganic salt precipitation rate in water provided by the present invention, the detection method is to confirm the type of inorganic salt precipitated in the early water quality analysis and know the inorganic carbon methyl orange alkalinity, pH, one of the three total dissolved inorganic carbon in the water, the total dissolved solid content of the water, the element and its content of the target inorganic salt contributing to the non-inorganic carbon methyl orange alkalinity, by detecting the change of the concentration of carbon dioxide in the water or the concentration of gaseous carbon dioxide in balance with it over time under a closed constant temperature and pressure environment, and calculate the precipitation rate of the target inorganic salt in water. The detection method provided by the present invention can be automatically processed and calculated by a computer program, and the present invention can improve the efficiency of the scheme evaluation when the precipitation rate of the target inorganic salt in the laboratory is detected and the precipitation rate adjustment scheme is verified, greatly improving the detection accuracy and reducing the manual effort. Similarly, the present invention is applied to the optimization of the precipitation rate in water of the target inorganic salt and the precipitation rate adjustment scheme for on-site detection, and provides a precipitation rate detection system in inorganic salt water with a low detection limit, less manual intervention, and short detection time, which provides an excellent tool for automatic optimization and adjustment of the on-site inorganic salt precipitation rate. The present invention has great potential in intelligent water treatment, including but not limited to applications in the following fields: circulating cooling water, surface water, geothermal water and drinking water, concentrated water in reverse osmosis water systems, concentrated water in thermal seawater desalination, water with a tendency to deposit colloidal silica and magnesium silicate, scaling detection and regulation in brine vacuum salt production processes, scaling detection and regulation of related water systems in oil and gas production, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 A schematic diagram of a detection process for the precipitation rate of inorganic salts in water provided by an embodiment of the present invention;

[0072] Figure 2 A schematic diagram of the structure of a carbon dioxide concentration detector provided by an embodiment of the present invention;

[0073] Figure 3 A principle block diagram of a system for detecting the precipitation rate of inorganic salts in water provided by an embodiment of the present invention;

[0074] Figure 4a and Figure 4b It is a statistical diagram of the change of PCO2 over time in the determination of calcium carbonate precipitation rate in the embodiment;

[0075] Figure 5 Schematic diagram for comparing the precipitation rates of calcium carbonate calculated by the embodiment of the present invention and the traditional alkalinity titration method;

[0076] Figure 6a and Figure 6b They are schematic diagrams of obtaining the slope and intercept of the linear regression of the data from 30 minutes to 60 minutes in the calcium phosphate precipitation test in the embodiment;

[0077] Figure 7 A statistical diagram of the calcium phosphate precipitation rate obtained according to an embodiment of the present invention;

[0078] Figure 8 The present invention is a record of the change of PCO2 with time in the magnesium silicate precipitation rate measured in the embodiment;

[0079] Figure 9a-9d A schematic diagram of the slope and intercept of the linear regression of the data for the test time of 30 minutes to 60 minutes at different set temperatures in the example for determining the precipitation rate of magnesium silicate;

[0080] Fig.10 It is a statistical diagram of magnesium silicate precipitation rate;

[0081] Fig.11a and Fig.11b It is a record of the change of PCO2 with time in the colloidal silica precipitation test and a schematic diagram of the slope and intercept of the linear regression;

[0082] Fig.12 Statistical graph of colloidal silica precipitation rate;

[0083] Fig.13a The PCO2 records of field water and field water after adding antiscalant at different test temperatures. Fig.13b Linear regression of PCO2 measured at 25°C after 0.5 hours, Fig.13c Linear regression of PCO2 after 0.5 hours at 55°C and 75°C;

[0084] Fig.14 This is a statistical chart showing the results of calculating the type 1 calcium carbonate precipitation rate for on-site water.

[0085] Figure 2 middle:

[0086] 1-test container, 10-pipeline, 11-jacket, 12-insulation layer, 13-jacket water inlet valve, 14-test cup water inlet valve, 15-jacket water outlet valve, 16-test cup water outlet valve, 17-connecting hole, 2-gas constant temperature cooling unit, 21-first temperature sensor, 22-refrigeration plate, 23-first controller, 3-second constant temperature heating unit, 31-second temperature sensor, 32-heating wire, 33-second controller, 4-carbon dioxide detector, 41-detection cavity, 42-carbon dioxide sensor, 43-display converter, 5-gas phase pressure balance bag, 6-gas circulation pump, 7-gas distributor, 8-water to be tested, 9-first constant temperature heating unit, 91-heater, 92-third temperature sensor, 93-third controller. DETAILED DESCRIPTION

[0087] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0088] Figure 1 A schematic diagram of a detection process for the precipitation rate of inorganic salts in water provided in an embodiment of the present invention.

[0089] See also Figure 1 The method for detecting the precipitation rate of inorganic salts in water provided in this embodiment comprises the following steps:

[0090] S1: Obtain the type of inorganic salt precipitated in the water to be tested, one of the three: inorganic carbon methyl orange alkalinity (Cmalk), pH value, total dissolved inorganic carbon (DIC), total dissolved solid content of the water to be tested (which can be converted from the conductivity of water), and the element and content of the target inorganic salt that contributes to the alkalinity of non-inorganic carbon methyl orange;

[0091] The alkalinity of water refers to the total amount of substances in water that can react quantitatively with strong acids. Methyl orange alkalinity is the total amount of substances in water that can be quantitatively neutralized by strong acids until the methyl orange indicator changes from orange-yellow to orange-red (solution pH 4.4 to 4.5) (120). The source of methyl orange alkalinity in water is different depending on the water quality.

[0092] Water containing inorganic carbon methyl orange alkalinity refers to water containing carbon dioxide, bicarbonate, and carbonate. In water containing inorganic carbon methyl orange alkalinity, the three forms of inorganic carbon and the hydrogen ion concentration in water (H + ), inorganic carbon methyl orange alkalinity (Cmalk) has been studied maturely and quantitatively. The following is a brief description:

[0093] DIC=CO2w×(1+k'1 / (H + )+k'1×k'2 / (H + )^2,----(1)

[0094] Cmalk=50000×CO2w×(k'1 / (H + )+2×k'1×k'2 / (H + )^2)----(2)

[0095] pH = -log(H + )----(3)

[0096] Where CO2w ​​is the carbon dioxide concentration in the water to be tested, H +is the hydrogen ion concentration in the water to be tested, its negative logarithm is the pH of the solution, k'1 is the first-order dissociation constant of carbonic acid corrected by temperature and water ionic strength, k'2 is the second-order dissociation constant of carbonic acid corrected by temperature and water ionic strength, k'1, k'2 can be selected or calculated from the existing information and data according to the water quality characteristics, water temperature and water solid content of the water to be tested. It can be seen from the above formulas (1), (2) and (3) that among the four parameters of DIC, Cmalk, pH and CO2w, knowing any two of the four parameters can give the other two parameters; in a closed detection system with constant temperature and pressure, if one of the initial DIC, Cmalk and pH of water is known, and CO2w ​​is measured, the unknown two of the first three parameters can be calculated.

[0097] Under certain conditions, different types of inorganic salts will precipitate and dissolve in water. There is a lot of existing knowledge and calculation software to judge and calculate the possible types of sediments and thermodynamic tendencies in the target water. The present invention divides the total methyl orange alkalinity (Tmalk) and total dissolved inorganic carbon (DIC) in the water into three categories based on whether the inorganic salts change after precipitation. Type 1 is that both are changed, Type 2 is that only Tmalk is changed, and Type 3 is that neither is changed. Table 1 lists the classification results of common inorganic scales according to this classification principle and the quantitative change relationship of the components in the water after precipitation. As can be seen from Table 1, after the precipitation of calcium carbonate, the Cmalk and DIC of water are reduced, and the total dissolved inorganic phosphorus (DIP) and total dissolved inorganic silicon (DISi) are not changed; after the precipitation of calcium sulfate, Tmalk, DIC, DIP, and DISi are not changed; after the precipitation of calcium phosphate, Pmalk and DIP of water are reduced, but DIC is not changed; after the precipitation of magnesium silicate, Simalk of water is reduced, but DIC is not changed; colloidal silica is a self-polymer of silicate, and each silicate molecule produces a hydroxide after polymerization, which increases the alkalinity of water but does not change DIC. In summary, when type 1 or type 2 scale is generated in water, Tmalk in the water will change, changing the balance of the carbonate system, causing changes in pH and CO2w. According to the change value of CO2w, combined with the quantitative relationship between the amount of type 1 scale and type 2 scale precipitation and Tmalk, DIC, DIP, and DIsi, the amount of corresponding inorganic salt precipitation can be calculated.

[0098] Table 1 Quantitative changes of components in water after precipitation of common insoluble inorganic salts

[0099]

[0100] *Tmalk=Cmalk+Pmalk+Simalk+OHmalk

[0101] S2: Detect the change of the carbon dioxide concentration CO2w ​​in the water to be tested or the gas phase carbon dioxide concentration PCO2 in equilibrium with it over time in a closed constant temperature and pressure environment;

[0102] The detection of carbon dioxide concentration can be done by directly detecting the concentration CO2w ​​in water, or by detecting the concentration PCO2 in the gas phase space in equilibrium with water, and then calculating the carbon dioxide concentration CO2w ​​in water based on the Henry constant for carbon dioxide Kh, which is calculated by PCO2×Kh.

[0103] See also Figure 2 In a specific embodiment, a closed detector with a total volume of 500 ml and constant temperature heating and cooling is established to detect the gas phase carbon dioxide concentration in equilibrium with the water 8 to be tested. A gas circulation pump 6 and a carbon dioxide detector 4 are provided in the closed detector loop. During the detection, the gas phase carbon dioxide concentration is continuously recorded. Specifically, the closed detector includes a test container 1, a carbon dioxide detector 4, a first constant temperature heating unit 3 and a gas circulation pump 6. The water 8 to be tested is placed in the test container 1. The inlet of the carbon dioxide detector 4 is connected to the test container 1. The outlet of the carbon dioxide detector 4 is connected to the test container 1 through the gas circulation pump 6 to form a pipeline loop for the circulation of carbon dioxide. The first constant temperature heating unit 9 is arranged on the test container 1 to control the temperature of the test water in a constant temperature state.

[0104] In a specific embodiment, the test container 1 can be a test cup with a diameter of 65 mm and a height of 150 mm coated with Teflon coating. The test cup is provided with a test cup water inlet valve 14 and a test cup water outlet valve 16, and is provided with a jacket 11. The jacket 11 is wrapped outside the test container 1, and an insulation layer 12 is provided on the outer side of the jacket 11. A jacket water inlet valve 13 and a jacket water outlet valve 15 are provided on the jacket 11; a connecting hole 17 is opened at the top cover of the test container 1, and the connecting hole 17 is connected to the pipeline 10. In this embodiment, the pipeline 10 is a 304 stainless steel pipe with an outer diameter of 16 mm and an inner diameter of 9 mm. A gas constant temperature cooling unit 2 is sequentially arranged outside the pipeline between the test container 1 and the carbon dioxide detector 4. The gas constant temperature cooling unit 2 includes a first temperature sensor 21, a refrigeration plate 22 and a first controller 23. The refrigeration plate 22 is wrapped outside the pipeline. The cooling surface of the refrigeration plate 22 is tightly connected to the stainless steel outer tube through metal tin. The first temperature sensor 21 is arranged between the refrigeration plate 22 and the pipeline, that is, the first temperature sensor 21 is placed between the metal tin and the stainless steel outer tube. The first controller 23 (PID control) is electrically connected to the first temperature sensor 21 and the refrigeration plate 22 to control the temperature in the metal tin and the stainless steel tube at a first predetermined value. The first predetermined value can be 5±0.5°C. In this embodiment, the length of the stainless steel tube of the cooling section is 40 mm. The second constant temperature heating unit 3 includes a heating wire 32, a second temperature sensor 31 and a second controller 33. The heating wire 32 is wound outside the stainless steel tube. In this embodiment, the heating wire 32 is composed of two Teflon low-pressure heating wires with an outer diameter of 1.2 mm and a resistance of 10 ohms per meter, which are wound in parallel for 20 turns to form a heating section with a total length of 48 mm on the stainless steel tube. The second temperature sensor 31 is placed between the stainless steel outer tube wall and the heating wire 32, and the second controller 33 (PID control) is electrically connected to the heating wire 32 and the second temperature sensor 31 to control the pipeline temperature at a second predetermined value, and the second predetermined value is greater than the first predetermined value. In this embodiment, the second controller 33 controls the temperature of the stainless steel outer tube wall to be 55±0.5°C. The purpose of setting up the gas constant temperature cooling unit 2 and the second constant temperature heating unit 3 is to meet the requirements of the carbon dioxide sensor 41 (SenseAir S8 / 004-0-0053, produced by SenseAir of Sweden) selected in this experiment for the humidity in the detected gas. By setting up the gas constant temperature cooling unit 2 and the second constant temperature heating unit 3, the detected gas is first cooled and then heated to achieve the purpose of reducing the humidity in the detected gas. In other embodiments, a carbon dioxide sensor 41 with high humidity adaptability is selected, and the gas constant temperature cooling unit 2 and the second constant temperature heating unit 3 can be omitted.

[0105] After the humidity of the test gas is reduced by the gas constant temperature cooling unit 2 and the second constant temperature heating unit 3, the test gas enters the carbon dioxide detector 4, which includes a test cavity 41, a carbon dioxide sensor 42 and a display converter 43. In this embodiment, the test cavity 41 is a 316 stainless steel cylinder with an inner diameter of 25 mm and a height of 45 mm. The bottom of the test cavity 41 is connected to the upper part of the pipeline 10, and the top of the test cavity 41 is connected to the gas phase pressure balance bag 5 through a 316 stainless steel capillary with a diameter of 3 mm. The test cavity 41 is equipped with a carbon dioxide sensor 42, which is connected to the display converter 43, and the display converter 43 detects and records the carbon dioxide concentration once a minute. The gas phase pressure balance bag 5 is an aluminum foil air bag with a length and width of 100 mm and 80 mm, respectively, and is covered with a polytetrafluoroethylene film. One of the two ports of the gas phase pressure balance bag 5 is connected to the detection cavity 41, and the other port is connected to the gas circulation pump 6 after being connected to the capillary. The outlet of the gas circulation pump 6 is connected to the detection container 1 through a 316 capillary with a diameter of 3 mm and the gas is passed into the detection water through the gas distributor 7. The gas circulation flow rate is 60±20 ml / min. The first constant temperature heating unit 9 is used to heat and maintain the constant temperature of the test water, including a heater 91, a third temperature sensor 92 and a third controller 93. The heater 91 is arranged outside the bottom of the detection container 1, and the third temperature sensor 92 is arranged inside the detection container 1. The third controller 93 is electrically connected to the third temperature sensor 92 and the heater 91 respectively to control the temperature of the water to be tested 8 at the third preset temperature. When the test temperature is higher than 25 degrees Celsius, the first constant temperature unit 9 is used to heat and maintain the constant temperature of the test water. When the test temperature is equal to or less than 25°C, the test water temperature is maintained by external constant temperature water through the test cup jacket 11. According to measurement, the volume of the entire test system is 500 ml at 25°C. According to the previous measurement data of the system temperature control, the temperature of the test water can stabilize to the set value 20-25 minutes after the start of the test. The temperature deviation during constant temperature is ±0.5℃.

[0106] S3: Obtaining the precipitation amount of the target inorganic salt according to the data obtained in step S1 and step S2;

[0107] In the first embodiment, the target inorganic salt is calcium carbonate, and there are no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange in the water to be tested, and the steps are specifically as follows:

[0108] S311: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0109] S312: H has been obtained from S311 +(t0) and DIC(t0), CO2w(t1) at t1 is known, and H at t1 is calculated according to formula (5) + (t1), then calculate DIC(t1) according to formula (1), and calculate Cmalk(t1) according to formula (2).

[0110] The calculation process of formula (5) is as follows: the precipitation of calcium carbonate reduces the total dissolved inorganic carbon in the water and the contained methyl orange alkalinity causes the inorganic carbon methyl orange alkalinity in the water to decrease, and the two values ​​are equal. The left side of formula (4) represents the methyl orange alkalinity content of the precipitated calcium carbonate, and the right side of formula (4) represents the change in the inorganic carbon methyl orange alkalinity in the water, and the two are equal. Formula (4) can be calculated to formula (5)

[0111] (DIC (t0) -DIC (t1) )×100×1000=(Cmalk (t0) -Cmalk (t1) )--(4)

[0112] ∨

[0113] 10^5×DIC (t0) -10^5×DIC (t1) =Cmalk (t0) -Cmalk (t1)

[0114] ∨10^5×CO2w(t0)×(1+k'1 / H + (t0) +k'1k'2 / (H + (t0) )^2-10^5×CO2w(t1)×

[0115] (1+k'1 / H + (t1) +k'1k'2 / (H + (t1) )^2=CO 2(t0) ×(50000×k'1 / (H + (t0) +100000×k'1k'2 / (H + (t0) ^2)-

[0116] CO 2(t1) ×(50000×k'1 / (H + (t1) +100000×k'1k'2 / (H + (t1) ^2)

[0117] ∨

[0118] 2×CO2w(t0)-2×CO2w(t1)=CO2w(t1)×k'1 / H + (t1)-CO2w(t0)×k'1 / H + (t0)--(5)

[0119] S313: Calculate the amount of calcium carbonate precipitation according to formula (6).

[0120] Calcium carbonate precipitation amount CaCO3 = (DIC(t0)-DIC(t1))×10^5--(6).

[0121] The unit of calcium carbonate precipitation CaCO3 is mg / L.

[0122] In the second embodiment, the target inorganic salt is calcium phosphate, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity contributed by orthophosphate, and specifically includes the following steps:

[0123] S321: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0124] S322: Given CO2w(t1) and Cmalk(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1),

[0125] DIC(t0)=DIC(t1)=CO2w(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)----(7)

[0126] The precipitation of non-carbonate does not change DIC, and H is obtained from formula (7): + (t1).

[0127] S323: Given Tp(t0) at t0, DIP(t0) is obtained according to formula (9), formula (10)-(12) can be used to calculate formula (13), then Pmalk(t0) is calculated according to formula (13), DIP(t1) and Pmalk(t1) are calculated according to formulas (8) and (13), and the amount of calcium phosphate precipitation is calculated according to formula (14);

[0128] (DIP(t0)-DIP(t1)) / 2×2×50×1000=Cmalk(t0)+Pmalk(t0)-Cmalk(t1)-Pmalk(t1)-(8)

[0129] DIP=Tp / 95 / 1000-------------------------------------------------(9)

[0130] Pmalk=(PO4 3- )×2×50000+(HPO4 2- )×1×50000--(10)

[0131] (PO4 3- )=DIP×kp1×kp2×kp3 / ((H + )^3+(H + )^2×kp1+(H + )×kp1×kp2+kp1×kp2×kp3)-(11)

[0132] (HPO4 2- )=(PO4 3- )×(H + ) / kp3--(12)

[0133] Pmalk=(DIP×kp1×kp2×kp3 / ((H + )^3+(H + )^2×kp1+(H + )×kp1×kp2+kp1×kp2×kp3))×2×50000+(DIP×kp1×kp2×kp3 / ((H + )^3+(H + )^2×kp1+(H + )×kp1×kp2+kp1×kp2×kp3))×(H + ) / kp3×1×50000--(13)

[0134] Calcium phosphate precipitation amount Ca3(PO4)2=(DIP(t0)-DIP(t1)) / 2×310×1000--(14)

[0135] Where Pmalk is the alkalinity of inorganic phosphorus methyl orange mg / L in terms of calcium carbonate, DIP is the total dissolved inorganic phosphorus mol / L, Tp is the total dissolved inorganic phosphorus content mg / L in terms of PO4 3- kp1 is the first order ionization constant of phosphoric acid, kp2 is the second order ionization constant of phosphoric acid, kp3 is the third order ionization constant of phosphoric acid; the unit of calcium phosphate precipitation amount Ca3(PO4)2 is mg / L.

[0136] After the precipitation of calcium phosphate, the total dissolved inorganic phosphorus (DIP) in the water and the methyl orange alkalinity contributed by phosphate (non-inorganic carbon methyl orange alkalinity) decreased. The left side of formula (8) is the methyl orange alkalinity expressed by the precipitated calcium phosphate, and the right side is the reduction of methyl orange alkalinity in the water. The two must be equal.

[0137] CO2w(t0)=PCO2t0×Kh and CMalk(t0) are known values, and H can be calculated according to formula (2): + (t0), and then DIC(t0) is obtained according to formula (1). Calcium phosphate does not contain carbonates, and does not change the DIC in water after precipitation from water, that is, DIC(t1) = DIC(t0). Therefore, H can be obtained according to formula (7). + (t1), and then Cmalk(t1) is obtained according to formula (2). So far, only DIP(t1) and Pmalk(t1) are unknown in formula (8), and DIP(t1) and Pmalk(t1) must satisfy formula (13). Therefore, DIP(t1) and Pmalk(t1) can be obtained by solving formula (8) and formula (13). One solution is the DIP(t1) trial and error method. By setting different DIP(t1) values, DIP(t1) and Pmalk(t1) that satisfy formula (8) and formula (13) are calculated, and then the precipitation amount of calcium phosphate is obtained according to formula (14).

[0138] In a third embodiment, the target inorganic salt is magnesium silicate, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity contributed by silicate, and specifically includes the following steps:

[0139] S331: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0140] S332: Given CO2w(t1) and Cmalk(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1);

[0141] DIC(t0)=DIC(t1)=CO2w(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)----(7)

[0142] S333: Given Tsi(t0) at t0, calculate DISi(t0) according to formula (16), calculate Simalk(t0) according to formulas (17) and (18), calculate DISi(t1) according to formulas (15)-(18), and calculate the amount of magnesium silicate precipitation according to formula (19);

[0143] (DISi(t0)-DISi(t1))×2×50×1000=Cmalk(t0)+Simalk(t0)-Cmalk(t1)-Simalk(t1)--(15)

[0144] DISi=Tsi / 60 / 1000--(16)

[0145] Simalk=50000×(Si(OH)3O - )--(17)

[0146] (Si(OH)3O - )=DISi / (1+H + / Ksi)--(18)

[0147] Magnesium silicate precipitation amount MgSiO3 = (DISi(t0)-DISi(t1))×2×50×1000--(19)

[0148] Where DISi is the total dissolved inorganic silicon mol / L, Tsi is the total dissolved silicon content, mg / L in terms of SiO2, Simalk is the alkalinity of inorganic silicon methyl orange mg / L in terms of calcium carbonate, Ksi is the dissociation constant of silicic acid; the unit of magnesium silicate precipitation amount MgSiO3 is mg / L.

[0149] After the magnesium silicate is precipitated, the alkalinity in the water decreases. The left side of formula (15) is the alkalinity of methyl orange expressed by the precipitated magnesium silicate, and the right side is the alkalinity reduction in the water. The two must be equal.

[0150] CMalk(t0) and CO2w(t0)=PCO2(t0)×Kh are known values. According to formula (2), H + (t0), and then DIC(t0) is obtained according to formula (1). Magnesium silicate precipitates from water, reducing the methyl orange alkalinity of water and causing the pH to decrease. Since non-carbonate alkalinity does not contain inorganic carbon, the DIC of water remains unchanged. According to formula (7), H +(t1), and then Cmalk(t1) is obtained. From the molecular formula of magnesium silicate, it can be seen that the precipitation of 1 mol / L of magnesium silicate will reduce the alkalinity in terms of calcium carbonate by 2×50×1000mg / L while reducing the total dissolved silicon by 1 mol / L, that is, (DISi(t0)-DISi(t1))×2×50×1000=Talk(t0)-Talk(t1). The total dissolved inorganic silicon concentration Tsi(t0) at t0 is known, and H at t0 is known. + (t0), the alkalinity Simalk(t0) contributed by silicon at t0 can be calculated based on the dissociation constant of silicate. When a DISi(t1) value is set, Simalk(t1) can be calculated from H + (t1) and the dissociation constant of silicate are obtained. Therefore, DISi(t1) can be calculated by trial and error to find DISi(t1) that satisfies equation (15), and then the precipitation amount of magnesium silicate can be obtained according to formula (19).

[0151] In a fourth embodiment, the target inorganic salt is colloidal silicon, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate, and specifically includes the following steps:

[0152] S341: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0);

[0153] S342: Given CO2w(t1) and Cmalk(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1), calculate Cmalk(t1) at t1 according to formula (2);

[0154] DIC(t0)=DIC(t1)=CO2w(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)----(7)

[0155] S343: Given Tsi(t0) at t0, DISi(t0) is obtained according to formula (16), Simalk(t0) is calculated according to formulas (17) and (18), DISi(t1) is calculated according to formulas (16)-(18) and (20), and the amount of colloidal silica precipitation is calculated according to formula (21);

[0156] (DIsi(t0)-DIsi(t1))×1×50×1000=-(Cmalk(t0)+Simalk(t0))+(Cmalk(t1)+Simalk(t1))-(20)

[0157] DISi=Tsi / 60 / 1000--(16)

[0158] Simalk=50000×(Si(OH)3O - )=50000×DISi / (1+H + / Ksi)--(17)

[0159] (Si(OH)3O - )=DISi / (1+H + / Ksi)--(18)

[0160] The amount of colloidal silicon precipitated SiO2 = (DISi(t0)-DISi(t1))×1×60×1000---(21).

[0161] The unit of colloidal silicon precipitation amount SiO2 is mg / L.

[0162] Cmalk(t0) and CO2w(t0)=PCO2(t0)×Kh are known values, and H can be calculated according to formula (2) + (t0), and then DIC(t0) is obtained according to formula (1). Since colloidal silica does not contain inorganic carbon, the DIC of water remains unchanged. According to formula (7), H + (t1), and then obtain Cmalk(t1).

[0163] Colloidal silica is the self-polymerization of orthosilicic acid. After each polymerization of orthosilicic acid, a hydroxide is generated in the water, and the alkalinity of the water increases. The left side of formula (20) is a quantitative expression of the increase in the alkalinity of the water while reducing the total dissolved inorganic silicon (DISi, mol / L) by the precipitated colloidal silica, and the right side is the increase in alkalinity in the water. The two must be equal.

[0164] Knowing the total dissolved inorganic silicon concentration Tsi at t0, DISi(t0) can be obtained by formula 16, and then according to the known H at t0 + (t0) Combined with the dissociation constant of silicate, the basicity Simalk(t0) contributed by silicon at t0 is calculated. Therefore, in formula (20), DISi(t1) and Simalk(t1) are still unknown. DISi(t1) and Simalk(t1) satisfy formula (17), H +(t1) is a known value, so DISi(t1) and Simalk(t1) can be solved according to formula (20) and formula (17). One solution method is the DISi(t1) trial and error method, which finds the DISi(t1) that satisfies formulas (20) and (17), and then calculates the amount of colloidal silica precipitation according to formula (21).

[0165] S4: Obtain the precipitation rate of the target inorganic salt according to the precipitation amount obtained in step S3.

[0166] The average precipitation rate during the test period is obtained by dividing the precipitation amount by the time (t1-t0) when the precipitation occurs.

[0167] This embodiment also provides an electronic device, including: a processor; a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned method for detecting the precipitation rate of the target inorganic salt is implemented.

[0168] This embodiment also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned method for detecting the precipitation rate of the target inorganic salt is implemented.

[0169] Example 1

[0170] In this embodiment, the precipitation rate of calcium carbonate is calculated based on the detection result of the gas phase carbon dioxide concentration PCO2 according to a calculation software developed according to the present invention.

[0171] It is known from the preliminary water quality analysis and scaling tendency judgment that the water to be tested has a tendency to precipitate calcium carbonate, and there are no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange in the water to be tested. It is known that the Cmalk of the water is 320mg / L and the TDS is 1118mg / L. Add 470ml of test water to the test device, set the test water temperature to 25℃, turn on the test device, and continuously detect and record PCO2. After one hour, the test is over. It is known from the PCO2 recorded in the test that PCO2=994ppmv at the 30th minute of the test and PCO2=1099ppmv at the 60th minute. Table 2 lists the specific steps for calculating the amount of calcium carbonate precipitation using a calculation software developed according to the present invention. The precipitation amount calculated from Table 2, divided by the time when the precipitation amount is generated, the average precipitation rate in the test time period is 1.8 / 0.5=3.6mg / L / hour.

[0172] Table 2 Calculation process of calcium carbonate precipitation

[0173]

[0174]

[0175]

[0176] Example 2

[0177] In this embodiment, the precipitation rate of calcium phosphate in type 2 scale is calculated based on the detection result of gas phase carbon dioxide concentration PCO2 and a calculation software developed according to the present invention.

[0178] It is known from the previous water quality analysis and scaling tendency judgment that the water has a tendency to precipitate calcium phosphate, and the water to be tested contains non-inorganic carbon methyl orange alkalinity except orthophosphate, and no other ions that contribute to non-inorganic carbon methyl orange alkalinity. It is known that the Cmalk of the water is 30 mg / L, the total dissolved solids (TDS) is 702 mg / L, and the inorganic phosphorus content is PO4 3- =15mg / L. In the test device, add 470ml of test water, set the test water temperature to 55℃, turn on the test device, and continuously detect and record PCO2. After one hour, the test is over. From the PCO2 recorded in the test, it is known that PCO2=5999ppmv at the 30th minute of the test, and PCO2=6241 at the 60th minute. Table 3 lists the specific steps for calculating the amount of calcium phosphate precipitation according to a calculation software developed according to the present invention. The precipitation amount calculated from Table 3 is divided by the time when the precipitation amount is generated, and the average precipitation rate of calcium phosphate during the test period is 0.56 / 0.5=1.12mg / L / hour.

[0179] Table 3 Calculation method of calcium phosphate precipitation

[0180]

[0181]

[0182]

[0183] Example 3

[0184] In this embodiment, the magnesium silicate deposition rate in type 2 scale is calculated based on the gas phase carbon dioxide concentration PCO2 detection result and a calculation software developed according to the present invention.

[0185] It is known from the previous water quality analysis and scaling tendency judgment that the water has a tendency to deposit magnesium silicate scale, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate. It is known that the Cmalk of the water is 266mg / L, TDS is 1870mg / L, and silicate is 400mg / L (in terms of SiO2). In the test device, add 470ml of test water, set the test water temperature to 55℃, turn on the test device, and continuously detect and record PCO2. After one hour, the test is over. From the carbon dioxide data recorded in the test, it is known that PCO2=5002ppmv at the 30th minute of the test, and PCO2=5798 at the 60th minute. Table 4 describes how to calculate the amount of magnesium silicate precipitation. The precipitation amount calculated from Table 4 is 3.02 mg / L in terms of MgSiO3. Dividing it by the time when the precipitation occurs, the average deposition rate during the test period is 3.02 / 0.5=6.0 mg / L / hour.

[0186] Table 4 Calculation method of magnesium silicate precipitation

[0187]

[0188]

[0189]

[0190] Example 4

[0191] The colloidal silica deposition rate in type 2 scale is calculated using a calculation software developed according to the present invention based on the PCO2 detection results.

[0192] It is known from the previous water quality analysis and scaling tendency judgment that the water has a tendency to deposit colloidal silica, and in addition to the non-inorganic carbon methyl orange alkalinity contributed by silicates, there are no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange in the water to be tested. It is known that the Cmalk of the water is 200mg / L, the TDS is 1700mg / L, and the silicate is 500mg / L (in terms of SiO2). In the test device, add 470ml of test water, set the test water temperature to 25℃, turn on the test device, and continuously detect and record the gas phase carbon dioxide concentration. After one hour, the test is over. From the carbon dioxide data recorded in the test, it is known that PCO2=1390ppmv at 20 minutes of the test, and PCO2=1320ppmv at 60 minutes. Table 5 describes how to calculate the amount of colloidal silica precipitation. The precipitation amount calculated from Table 5 is 0.99 mg / L in terms of SiO2. Dividing it by the time when the precipitation occurs, the average deposition rate during the test period is 0.99 / (60-20)*60=1.5 mg / L / hour.

[0193] Table 5 Calculation method of colloidal silicon precipitation amount

[0194]

[0195]

[0196]

[0197] The specific application of the present invention in laboratory testing of the crystallization reaction characteristics of a target inorganic salt (process 1) is further described below.

[0198] Example 5

[0199] This embodiment is a calcium carbonate crystallization test.

[0200] In the laboratory, in order to evaluate the crystallization reaction characteristics of the target inorganic salt precipitated from the water, an existing method is the static scale inhibition method, which uses two reserve solutions to prepare. When the two reserve solutions are mixed and under a certain test environment, the target inorganic salt will be crystallized and precipitated. By analyzing the concentration of the target ion before and after the test, the precipitation characteristics of the target inorganic salt are quantitatively evaluated. In this test, while using the carbon dioxide concentration detection device and calculation method of the present invention to obtain the precipitation rate of calcium carbonate, the total methyl orange alkalinity of the water before and after the test is analyzed to obtain a set of data similar to the traditional static scale inhibition test, and then the calcium carbonate precipitation amount and deposition rate are calculated based on the data and the two sets of data are compared.

[0201] 1. Experimental Preparation

[0202] 1) Preparation of 0.5 mg (effective) ATMP / ml stock solution

[0203] Weigh 0.25 g of 50% ATMP (a commonly used scale inhibitor, aminotrimethylenephosphonic acid, purchased from Taobao, Youso Sample Xiaolin Store) into a 200 ml beaker, add about 100 ml of deionized water and mix well, adjust the pH to 7.0±0.1 with 0.1 N NaOH, and then make up to 250 ml with deionized water.

[0204] 2) Preparation of stock solutions A and B

[0205] Stock solution A: weigh 1.813 g NaHCO3 (analytical grade, Chinese medicine) into a 200 ml beaker, dissolve it with about 100 ml deionized water and transfer it to a 2 liter volumetric flask, weigh 0.127 g Na2CO3 (analytical grade, Chinese medicine) into a 200 ml beaker, dissolve it with 100 ml deionized water and transfer it to a 2 liter volumetric flask, then wash the 200 ml beaker 2-3 times with deionized water, and transfer the washing liquid to a 2 liter volumetric flask. Repeat the preparation of stock solution A once, mix the two prepared stock solutions A, put them into a 5 liter glass bottle, and cover the bottle cap for later use.

[0206] Stock solution B: weigh 1.763 g of CaCl2×2H2O (analytical grade, Fuchen (Tianjin) Chemical Reagent Co., Ltd.) into a 200 ml beaker, dissolve it with about 100 ml of deionized water, and transfer it to a 2-liter volumetric flask. Wash the 200 ml beaker 2-3 times with deionized water, transfer the washing solution to a 2-liter volumetric flask, and make up the volume of the 2-liter volumetric flask with deionized water. Repeat the preparation of stock solution B, mix the two prepared stock solutions B, put them into a 5-liter glass bottle, and cover the bottle cap for later use.

[0207] 3) Titration of initial methyl orange alkalinity: Take 250 ml of stock solution A in a volumetric flask, take 250 ml of deionized water in another volumetric flask, mix the two liquids and store in a 500 ml glass bottle with a lid. Filter the sample with a 0.45 micron filter membrane (Water System MCE 25mm, DeFilter Technology), take a sample with a 50 ml pipette and transfer it to a 200 ml conical flask, add 3-5 drops of 0.1% methyl orange indicator and titrate with 0.05N HCl standard solution (Taobao, Laboratory Standard Reagent Store). Repeat 3 times for each sample, take the average, and calculate the standard deviation.

[0208] 2. Calcium carbonate crystallization test

[0209] Use a 250ml volumetric flask to take 250ml of stock solution A and put it into a 1000ml beaker. According to the experimental design, add different amounts of ATMP stock solution. Use another 250ml volumetric flask to take 250ml of stock solution B, put it into the 1000ml beaker containing stock solution A, and stir it evenly with a glass rod. The calculated water quality after the two stock solutions are mixed in equal amounts is shown in Table 6. According to the relevant calculation software, it can be known that the calcite supersaturation index of the test solution is 1.68 at 25℃. Take 470 grams of the test solution and place it in the test device. Set the test constant temperature to 25℃ and the test time to 1 hour. During this period, continuously record PCO2 and draw a curve of change over time after the test. After 1 hour, the test solution is filtered with a 0.45 micron filter membrane, sampled with a 50ml pipette and transferred to a 200ml conical flask, dripped 3-4 drops of methyl orange indicator, and titrated with 0.05N HCl. Repeat 3 times, take the average, and calculate the standard deviation.

[0210] Table 6. Water quality for calcium carbonate precipitation test

[0211]

[0212] *aqion is a free water quality calculation software that can determine the dissolution and deposition tendency of 261 minerals based on water quality. Download URL: https: / / www.aqion.de / direct / 8.1.2_EN

[0213] 3. Test results

[0214] Table 7 shows the test arrangement and test result statistics. Figure 4a and Figure 4b This is a statistical graph showing changes in PCO2 over time.

[0215] According to the constant temperature characteristic test of the previous test device, the water temperature can be kept constant at 25±0.5℃ only after about 20-25 minutes from the start of the test. Therefore, the slope and intercept of the data from 30 minutes to 60 minutes of the test are obtained by linear regression. Figure 5 , and the PCO2 at 0 minutes and 60 minutes is calculated from the slope and intercept, and then the calcium carbonate precipitation amount and deposition rate are calculated with this value. The final calculated results are listed in Table 7.

[0216] Table 7. Calcium carbonate crystallization test arrangement and results

[0217]

[0218]

[0219] *Total dissolved solids (mg / L) is calculated as 0.7×conductivity (μs / cm)

[0220] Figure 5 A comparative schematic diagram of the calcium carbonate deposition rate calculated according to the present invention and by the traditional alkalinity titration method is listed.

[0221] From this experiment, it can be seen that

[0222] 1) Measured in terms of CaCO3, the absolute error of alkalinity titration is about 5 mg / L, that is, the resolution of calcium carbonate deposition rate calculated by the alkalinity method is less than 5 mg / L / hour.

[0223] 2) From the two repeated data of the method of the present invention at 25bbp, 75bbp, and 100ppb, it can be seen that the resolution of the method of the present invention is about 2mg / L / hour.

[0224] 3) At 0ppb ATMP addition, the results obtained by the two methods have a large deviation of about 5mg / L / hour. The possible reason is that the sample without antiscalant still maintains a high deposition rate after 1 hour, sampling and filtration takes about 15 minutes, and each alkalinity measurement takes about 5 minutes. Therefore, the data measured by the alkalinity method is actually about 1.5 hours, 25 / 1.5=17mg / L / hour, which is close to the data measured by the method of the present invention.

[0225] 4) The present invention does not require high-intensity alkalinity titration, has a small workload, continuous detection data, no need for manual intervention, and high reliability.

[0226] Example 6

[0227] This example is a calcium phosphate precipitation test.

[0228] 1. Experimental Preparation

[0229] 1) 3g / L (PO4 3- Preparation of phosphate stock solution

[0230] Weigh 4.36 g of NaH2PO4×H2O (analytical grade, Chengdu Kelong Chemical Co., Ltd.) into a 200 ml beaker, dissolve it with about 100 ml of deionized water and transfer it to a 1-liter volumetric flask. Wash the 200 ml beaker 2-3 times with 100 ml of deionized water, transfer the washing liquid to a 1-liter volumetric flask, and then make up the volume of the 1-liter volumetric flask with deionized water.

[0231] 2) Preparation of stock solution A

[0232] Weigh 0.202 g of NaHCO3 into a 200 ml beaker, dissolve it with about 100 ml of deionized water and transfer it to a 1 L volumetric flask. Wash the 200 ml beaker 2-3 times with 100 ml of deionized water, transfer the washing solution to a 2 L volumetric flask, pipette 20 ml of 3 g / L phosphate stock solution into the volumetric flask, mix well, and make up the volume of the 2 L volumetric flask with deionized water.

[0233] 3) Preparation of stock solution B

[0234] Weigh 2.35 g of CaCl2×2H2O into a 200 ml beaker, dissolve it with about 100 ml of deionized water and transfer it to a 1 liter volumetric flask. Wash the 200 ml beaker 2-3 times with 100 ml of deionized water, transfer the washing liquid to a 2 liter volumetric flask, and make up the volume of the 2 liter volumetric flask with deionized water.

[0235] 2. Calcium phosphate precipitation test

[0236] Use a volumetric flask to take 250ml of stock solution A into a 1-liter beaker, add the antiscalant stock solution according to Table 1, and then use another volumetric flask to take 250ml of stock solution B into the 1-liter beaker containing solution A and antiscalant stock solution, mix well, and weigh 470 grams into the test device. Run the test according to the test design.

[0237] According to the amount of inorganic salt added, the water quality of the prepared water is listed in Table 8. It is calculated that the supersaturation index of calcium phosphate is 3.84 at 25°C.

[0238] 3. Test results

[0239] Table 9 shows the test arrangement and test result statistics. Figure 4 shows the record of PCO2 changes over time.

[0240] Table 8 Hydroxyapatite precipitation test water quality

[0241] <![CDATA[Na + ,mg / L]]> 14 <![CDATA[Ca 2+ ,mg / L as CaCO3]]> 400 <![CDATA[Cmalk,mg / L as CaCO3]]> 30 Cl-,mg / L 283 <![CDATA[Total Phosphorus (TP), mg / L as PO4 3 -equivalent]]> 15 pH, room temperature 7.5 Supersaturation index SI* of calcium phosphate at 25°C 3.84

[0242] *Calculation method:

[0243] SI=log((Ca2+)^3×PO43-)^2) / ksp(Ca3(PO4)2),

[0244] PO4 3- (mol / L)=Tp / 95 / 1000×kp1×kp2×kp3 / ((H+)^3+(H+)^2×kp1+(H+)×kp1×kp2+kp1×kp2×kp3)

[0245] Ca 2+ (mol / L)=(Ca 2+ ,mg / L as CaCO3) / 100 / 1000

[0246] KspCa3(PO4)2=2E-29

[0247] Kp1=4.92E-3, Kp2=6.48E-8, Kp3=4.37E-13

[0248] According to the constant temperature characteristics of the previous test device, the water temperature can be kept constant at 55±0.5℃ only about 20-25 minutes after the start of the test. Therefore, the slope and intercept of the data from 30 minutes to 60 minutes of the test are obtained by linear regression. Figure 6a and Figure 6b , and the PCO2 at 0 minutes and 60 minutes is calculated from the slope and intercept, and then the amount and rate of calcium phosphate precipitation are calculated using this value, Figure 7 It can be seen that the PCO2 of blank water without antiscalant is greater than 9999ppmv within 20 minutes. If the initial PCO2 is 5000ppmv, according to the calculation method of the present invention, the calcium phosphate precipitation rate is 10.1mg / L / hour, that is, the calcium phosphate precipitation rate of blank water is much greater than 10mg / L / hour. The final calculation results are listed in Table 9.

[0249] Figure 7 The statistics of calcium phosphate crystallization rates obtained according to the present invention are listed.

[0250] Table 9. Calcium phosphate precipitation test arrangement and results

[0251]

[0252] From this experiment, it can be seen that

[0253] 1) For blank water without scale inhibitor, the calcium phosphate precipitation rate is much greater than 10 mg / L / hour.

[0254] 2) Under the scale inhibitor and addition concentration selected in this test, the calcium phosphate precipitation rate will be less than 1.4 mg / L / hour.

[0255] 3) Under the two selected additive dosages, the present invention can still distinguish the difference in calcium phosphate precipitation rate, which cannot be achieved in the traditional static scale inhibition method that indicates the quality of the scale inhibitor by detecting the change in phosphate concentration.

[0256] 4) The present invention does not require high-intensity traditional phosphate concentration detection, has a small workload, continuous detection data, no need for manual intervention, and high reliability.

[0257] Example 7

[0258] This example is a magnesium silicate precipitation test.

[0259] 1. Test preparation:

[0260] 1) Preparation of 100 mg (based on commercial product) / ml QSY 5000 stock solution

[0261] Weigh 10.0 g of QSY5000 (Henan Qingshuiyuan Technology Co., Ltd.) into a 100 ml beaker, add about 30 ml of deionized water, neutralize with 0.1 N NaOH to pH = 7.0 ± 0.1, transfer to a 100 ml volumetric flask and make up to volume with deionized water.

[0262] Preparation of 5 mg (PBTC in terms of active substance) / ml stock solution

[0263] Weigh 1 gram of PBTC (a commonly used scale inhibitor, 2-phosphonobutane-1,2,4-tricarboxylic acid, purchased from Taobao, Youso Sample Xiaolin Store) with an effective content of 50% and put it into a 100 ml beaker, add about 30 ml of deionized water, neutralize it with 0.1N NaOH to pH = 7.0 ± 0.1, transfer it to a 100 ml volumetric flask and make up to volume with deionized water.

[0264] Preparation of 5 mg (AA / AMPS in terms of active substance) / ml stock solution

[0265] Weigh 1.25 g of 40% (AA / AMPS) (a commonly used scale inhibitor, a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid (AMPS), purchased from Taobao, Yousuo Sample Xiaolin Store) into a 100 ml beaker, add about 30 ml of deionized water and mix well, adjust the pH to 7.0±0.1 with 0.1N NaOH, and then make up to 100 ml with deionized water.

[0266] 2) Stock solution A

[0267] Weigh 0.34 g NaHCO3 into a 100 ml beaker, dissolve it with about 100 ml deionized water 3 to 4 times and wash the beaker, transfer it to a 1 L polypropylene plastic volumetric flask, weigh 1.89 g Na2SiO3×9H2O (analytical grade, Beilian Fine Chemicals) into a 100 ml beaker, dissolve it with 100 ml deionized water and transfer it to a 1 L polypropylene volumetric flask, then wash the 100 ml beaker 2-3 times with deionized water, transfer the washing liquid to a 1 L polypropylene volumetric flask, make up to volume and cover the bottle cap tightly for later use.

[0268] 3) Stock solution B

[0269] Weigh 2.46 g of MgSO4×7H2O (analytical grade, Tianjin Beichen Fangzheng Reagent Factory) into a 100 ml beaker, dissolve it with about 100 ml of deionized water and transfer it to a 2-liter volumetric flask, then wash the 100 ml beaker 2-3 times with deionized water, transfer the washing solution to a 2-liter volumetric flask, weigh 0.06 g of CaCl2×2H2O into a 100 ml beaker, dissolve it with about 50 ml of deionized water and transfer it to a 2-liter volumetric flask, then wash the beaker with about 100 ml of deionized water and transfer the solution to a 2-liter volumetric flask, then make up the 2-liter volumetric flask with deionized water and cover the bottle cap for later use.

[0270] Table 10 calculates the water quality of the magnesium silicate precipitation test based on the type and amount of inorganic salt added.

[0271] Table 10. Water quality of magnesium silicate precipitation test

[0272]

[0273]

[0274] 2. Magnesium silicate precipitation test

[0275] 1) Blank test without adding scale inhibitor

[0276] Take 250g of stock solution A, adjust the pH to 8.5±0.1 with 0.5N H2SO4 and 0.1NaOH, then add 250g of stock solution B, mix well, take 470g and put it into the test cup and start the test. The temperature of the first hour is set to 25℃, the temperature of the second hour is set to 55℃, the temperature of the third hour is set to 65℃, and the temperature of the fourth hour is set to 75℃. After 4 hours, the test is over.

[0277] 2) Test of adding antiscalant

[0278] The only difference from the blank test is that before adjusting the pH, 0.5 ml of QSY 5000 stock solution, 1.2 ml of 5 mg (PBTC in terms of active matter) / ml stock solution, and 2.4 ml of 5 mg (AA / AMPS in terms of active matter) / ml stock solution are added. The test temperature is the same as that without adding scale inhibitor.

[0279] 3. Test results

[0280] Table 10 shows the detailed water quality components of the prepared water calculated based on the amount of inorganic salt added. Table 11 shows the test arrangement and test result statistics. Figure 8 It is a record of PCO2 changes over time.

[0281] According to the constant temperature characteristic test of the previous test device, the water temperature can be kept constant at ±0.5℃ of the set temperature about 20-25 minutes after the start of the test. Therefore, the slope and intercept of the data of the test time of 30 minutes to 60 minutes at different set temperatures are obtained by linear regression. Figure 9a-9d The slope and intercept were used to calculate the extrapolated PCO2 at 0 minutes and 60 minutes at different temperatures, and then the precipitation amount and precipitation rate of magnesium silicate were calculated using the values. The final calculated results are listed in Table 11. Fig.10 Statistics for the precipitation rate of magnesium silicate.

[0282] Table 11 Magnesium silicate precipitation test arrangement and results

[0283]

[0284] *100mg / L QSY5000+24mg / L AA / AMPS+12mg / L PBTC

[0285] From this experiment, it can be seen that

[0286] 1) When the temperature of blank water and water with scale inhibitor is below 55℃, no magnesium silicate precipitation is detected.

[0287] 2) At 65℃ and 75℃, the precipitation rate of magnesium silicate in blank water was 0.2 and 1.0 mg / L / hour, while that in water with scale inhibitor was only 0.0 and 0.2 mg / L / hour.

[0288] 3) The present invention can effectively distinguish the difference of at least 1 mg / L / hour in the precipitation rate of magnesium silicate, which is not possible in the static scale inhibition test.

[0289] 4) The present invention can realize flexible adjustment of crystallization conditions and obtain results under different conditions simply and quickly.

[0290] 5) Compared with the traditional static scale inhibition test, the present invention does not require the traditional wet chemical analysis method of high-strength silicate, has a small workload, continuous detection data, no need for manual intervention, and high reliability.

[0291] 6) Since the detection of carbon dioxide concentration does not require manual operation, high-frequency detection can be achieved (in this example, detection and recording are selected once every 1 minute), and the reliability of its detection value is unmatched by traditional wet chemical analysis methods.

[0292] Example 8

[0293] This example is a colloidal silica precipitation test.

[0294] 1. Experimental Preparation

[0295] Preparation of 30mg / ml NaHCO3 stock solution

[0296] Weigh 3.00 g of NaHCO3 and dilute to volume in a 100 ml volumetric flask with deionized water for later use.

[0297] Preparation of 100 mg / ml QSY5000 stock solution

[0298] Weigh 0.100 g of QSY5000 in a 100 ml beaker, add about 30 ml of deionized water, neutralize to pH 7.0 ± 0.1 with 0.1 N NaOH, then transfer to a 100 ml volumetric flask and make up to volume with deionized water.

[0299] 2. Precipitation test

[0300] Test #1: Weigh 1.18 g of Na2SiO3×9H2O and transfer it to a 1000 ml beaker containing about 300 ml of deionized water. After dissolving, adjust the pH to about 8.3 with 1N H2SO4, then adjust the pH to 8.5±0.1 with 0.1N H2SO4 and 0.1N NaOH, then add 5.6 ml of 30 mg / ml NaHCO3 stock solution, transfer the solution to a 500 ml volumetric flask and make up to volume with deionized water. Weigh 470 g of the liquid into the test apparatus. According to the test design, run the test apparatus.

[0301] Test #2 was the same as Test #1 except that the amount of Na2SiO3×9H2O was adjusted to 0.71 g.

[0302] In test #3, 1.5 ml of 100 mg / ml QSY5000 stock solution was added before the final solution was made up to volume. The rest was the same as in test #2.

[0303] Test #4 was the same as Test #1 except that the amount of Na2SiO3×9H2O was adjusted to 0.47 g.

[0304] The water quality of the test was calculated based on the type and concentration of inorganic salts added, see Table 12.

[0305] Table 12 Water quality of colloidal silicon precipitation test

[0306]

[0307] 3. Test results

[0308] Table 13 shows the test arrangement and result statistics. Fig.11a and Fig.11b It is a record of PCO2 changes over time.

[0309] According to the constant temperature characteristic test of the previous test device, the water temperature can be kept constant at ±0.5℃ of the set temperature about 20-25 minutes after the start of the test. Therefore, the slope and intercept of the data of the test time of 30 minutes to 60 minutes at different set temperatures are obtained by linear regression. Fig.12 , and the extrapolated PCO2 at 0 minutes and 60 minutes was calculated from the slope and intercept, and then the precipitation amount and precipitation rate of colloidal silica were calculated using this value. The final calculated results are listed in Table 11. Fig.12 Statistics for the precipitation rate of colloidal silica.

[0310]

[0311] *Total dissolved solids are calculated as conductivity x 0.70

[0312] From this experiment, it can be seen that

[0313] 1) Under the experimental conditions, the colloidal silica precipitation rates of water with an initial active silica concentration of 200, 300, and 500 mg / L are -0.1, 1.2, and 1.4 mg / L / hour, respectively. The present invention can distinguish a difference of about 0.2 mg / L / hour in the precipitation rate of colloidal silica, that is, the resolution is about 0.2 mg / L / hour.

[0314] 2) When 300mg / L QSY5000 is added to water with an initial active silica concentration of 300mg / L, the colloidal silica precipitation rate is 0.8mg / L / hour, which is 0.4mg / L / hour lower than that without adding scale inhibitor. If the precipitation rate without adding scale inhibitor is used as the denominator and the difference in precipitation rate is used as the numerator to calculate the scale inhibition rate, it is 34%.

[0315] 3) The present invention can effectively distinguish the difference of at least 0.2 mg / L / hour in the precipitation rate of colloidal silica under the test conditions, which is impossible to achieve in the static scale inhibition test.

[0316] 4) The present invention does not require high-intensity traditional silicate concentration detection, has a small workload, continuous detection data, no need for manual intervention, and high reliability.

[0317] 5) Since the detection of carbon dioxide concentration does not require manual operation, high-frequency detection can be achieved (this embodiment selects detection and recording once per minute), and the reliability of its detection value is unmatched by traditional wet chemical analysis methods.

[0318] Example 9

[0319] The following further describes a specific application example of the present invention in process 2 (detecting the crystallization reaction characteristics of inorganic salts in field applications).

[0320] A circulating cooling water uses municipal tap water as make-up water and adopts phosphorus-free circulating water corrosion and scale inhibition treatment. In actual field applications, it was found that the scaling control of some high-temperature heat exchangers was poor, and the treatment plan of scale and corrosion inhibitor was adjusted. The water quality analysis results of the field water are shown in Table 12. Judging from the water quality and the source of make-up water, the main scaling inorganic salt of the circulating water is calcium carbonate.

[0321] The on-site circulating water was taken and the on-site water and the on-site water supplemented with scale inhibitor were measured at 25°C, 55°C and 75°C by the method of the present invention. The precipitation rate calculation method of the precipitated inorganic salt type 1 calcium carbonate was used to calculate the precipitation rate. Table 12 shows the test arrangement and results. Fig.13a The PCO2 records of field water and field water after adding antiscalant at different test temperatures. Fig.13b Linear regression of PCO2 measured at 25°C after 0.5 hours, Fig.13c Linear regression of PCO2 after 0.5 h for 55 °C and 75 °C. Fig.14 The results of the calculation of the precipitation rate of calcium carbonate in the field water according to type 1 are summarized in the table. Fig.14 It can be seen that at 25°C and 55°C, the precipitation rate of calcium carbonate in the on-site water is less than 0.9 mg / L / hour. However, when the temperature rises to 75°C, the precipitation rate of calcium carbonate in the water without adding additional scale inhibitors will rapidly increase to 6.7 mg / L / hour. The water with added scale inhibitors can still maintain a temperature of 0.6 mg / L / hour, which is approximately equivalent to that at 55°C without adding scale inhibitors. This shows that for high-temperature heat exchangers, the current on-site chemical treatment plan needs to be adjusted. One method is to increase the concentration of scale inhibitors. Considering the cost of the agent, other methods can also be used. For example, lowering the pH. After adjusting the treatment plan on site, water can be taken again to determine the precipitation rate of inorganic salts using the method of the present invention until the best inorganic salt precipitation control plan is found.

[0322] Table 12 On-site water test arrangements and results

[0323]

[0324]

[0325] *Total dissolved solids are calculated as conductivity x 0.70

[0326] From the above test, it can be seen that the present invention only takes 6 hours to test the above data, and the calculation process is fully programmed, and the manual input is only the initial Cmalk (or pH, or DIC) and TDS (which can be converted to conductivity) of the water. There is no need for frequent and complicated alkalinity or calcium ion analysis.

[0327] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A method for detecting the precipitation rate of inorganic salts in water, characterized in that: The steps include: S1: Obtain the type of inorganic salt precipitated in the water to be tested, obtain one of the three: inorganic carbon methyl orange alkalinity (Cmalk(t0)), pH(t0) value, total dissolved inorganic carbon (DIC(t0)), total dissolved solid content (TDS), and the element of the target inorganic salt that contributes to the non-inorganic carbon methyl orange alkalinity and its initial content in the water to be tested at the initial time (t0); combine the CO2w(t0) measured in step S2, and calculate the other two of the three: inorganic carbon methyl orange alkalinity (Cmalk), pH value, and total dissolved inorganic carbon (DIC) in the water at t0 according to formula (1), formula (2), and formula (3); calculate Cmalk(t0), DIC(t1), and pH(t1) according to Cmalk(t0), CO2w(t0), the type of inorganic salt precipitated in the water to be tested, and CO2w(t1) measured in step S2; DIC=CO2w×(1+k'1 / (H + )+k'1×k'2 / ( H + )^2), ----(1) Cmalk = 50000×CO2w×(k'1 / (H + )+2k'1×k'2 / (H + )^2), ----(2) pH= -log(H + ) ----(3) Where DIC is the total dissolved inorganic carbon concentration in water, mol / L, CO2w ​​is the carbon dioxide concentration in the water to be tested, mol / L, Cmalk is the alkalinity of inorganic carbon methyl orange in water, mg / L, calculated as calcium carbonate, H + is the hydrogen ion concentration in the water to be tested, mol / L, k'1 is the first-order dissociation constant of carbonic acid, and k'2 is the second-order dissociation constant of carbonic acid; S2: In a closed constant temperature and pressure environment, continuously detect the change value of the carbon dioxide concentration (CO2w) in the water to be tested over time, or continuously detect the change value of the gas phase carbon dioxide concentration (PCO2) in equilibrium with the water to be tested over time, and then obtain the change value of the carbon dioxide concentration CO2w ​​in the water over time based on the carbon dioxide Henry constant Kh; obtain the carbon dioxide concentrations CO2w(t0) and CO2w(t1) at t0 and t1; S3: Obtaining the precipitation amount of the target inorganic salt at time t1 according to the data obtained in step S1 and step S2; S4: Obtain the precipitation rate of the target inorganic salt according to the precipitation amount obtained in step S3 and the time in S2.

2. The detection method according to claim 1, characterized in that: The target inorganic salt is calcium carbonate, and there are no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange in the water to be tested. Step S3 includes the following steps: S311: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0); S312: Given CO2w(t1) at t1, calculate H at t1 according to formula (5) + (t1), Cmalk(t1) at t1 is calculated according to formula (2), and DIC(t1) at t1 is calculated according to formula (4). (DIC(t0)-DIC(t1))×100×1000=(Cmalk(t0)-Cmalk(t1)) --(4) 2×CO2w(t0)-2×CO2w(t1)=CO2w(t1)×k'1 / H + (t1)-CO2w(t0)×k'1 / H + (t0) --(5) S313: Calculate the amount of calcium carbonate precipitation according to formula (6) Calcium carbonate precipitation amount CaCO3 = (DIC (t0) - DIC (t1)) × 10^5 -- (6) The unit of calcium carbonate precipitation amount CaCO3 is mg / L.

3. The detection method according to claim 1, characterized in that: The precipitated inorganic salt is calcium phosphate, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity contributed by orthophosphate, and the step S3 comprises the following steps: S321: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0); S322: Given CO2w(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7). + (t1), calculate Cmalk(t1) at t1 according to formula (2); DIC(t0)=DIC(t1)=CO2w(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2) --(7) S323: Given Tp(t0) at t0, calculate DIP(t0) according to formula (9), calculate Pmalk(t0) according to formulas (10)-(12), calculate DIP(t1) according to formulas (8)-(12), and calculate the amount of calcium phosphate precipitation according to formula (14); (DIP(t0)-DIP(t1)) / 2×2×50×1000=Cmalk(t0)+Pmalk(t0)-Cmalk(t1)-Pmalk(t1) --(8) DIP = Tp / 95 / 1000 -- (9) Pmalk= (PO4 3- )×2×50000+(HPO4 2- )×1×50000--(10) (PO4 3- )=Tp / 95 / 1000×kp1×kp2×kp3 / ((H + )^3+(H + )^2×kp1+(H + )×kp1×kp2+kp1×kp2×kp3) --(11) <h2 style=";text-align:left;direction:ltr">(HPO4<h2 style=";text-align:left;direction:ltr"> 2- <h2 style=";text-align:left;direction:ltr"> )=(PO4<h2 style=";text-align:left;direction:ltr"> 3- <h2 style=";text-align:left;direction:ltr"> )×(H<h2 style=";text-align:left;direction:ltr"> + <h2 style=";text-align:left;direction:ltr"> ) / kp3--(12) Calcium phosphate precipitation amount Ca3(PO4)2=(DIP(t0)-DIP(t1)) / 2×310×1000 --(14) Where Pmalk is the alkalinity of inorganic phosphorus methyl orange in mg / L, expressed as calcium carbonate, DIP is the total dissolved inorganic phosphorus concentration in mol / L, Tp is the total dissolved inorganic phosphorus concentration in mg / L, expressed as PO4 3- kp1 is the first order ionization constant of phosphoric acid, kp2 is the second order ionization constant of phosphoric acid, kp3 is the third order ionization constant of phosphoric acid; the unit of calcium phosphate precipitation amount Ca3(PO4)2 is mg / L.

4. The detection method according to claim 1, characterized in that: The target inorganic salt is magnesium silicate, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate, and step S3 comprises the following steps: S331: Given Cmalk(t0) and CO2(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0); S332: Given CO2(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7). + (t1), calculate Cmalk(t1) at t1 according to formula (2), DIC(t0)=DIC(t1)=CO2(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2) --(7) S333: Given Tsi(t0) at t0, calculate DISi(t0) according to formula (16), calculate Simalk(t0) according to formulas (17) and (18), calculate DISi(t1) according to formulas (15)-(18), and calculate the amount of magnesium silicate precipitation according to formula (19); (DISi(t0)-DISi(t1))×2×50×1000=Cmalk(t0)+Simalk(t0)-Cmalk(t1)-Simalk(t1)--(15) DISi =Tsi / 60 / 1000 -- (16) <h2 style=";text-align:left;direction:ltr">Simalk=50000×(Si(OH)3O)<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> ) --(17) (Si(OH)3O - )=DISi / (1+H + / Ksi) --(18) Magnesium silicate precipitation amount MgSiO3 = (DISi(t0)-DISi(t1))×2×50×1000 -- (19) Where DISi is the total dissolved inorganic silicon content mol / L, Tsi is the total dissolved inorganic silicon content mg / L, calculated as SiO2, Simalk is the alkalinity of inorganic silicon methyl orange mg / L, calculated as calcium carbonate, Ksi is the dissociation constant of silicic acid; the unit of magnesium silicate precipitation amount MgSiO3 is mg / L.

5. The detection method according to claim 1, characterized in that: The target inorganic salt is colloidal silicon, and the water to be tested contains no other ions that contribute to the alkalinity of non-inorganic carbon methyl orange except for the alkalinity of non-inorganic carbon methyl orange contributed by silicate, and the step S3 comprises the following steps: S341: Given Cmalk(t0) and CO2w(t0) at t0, calculate H at the start time t0 according to formulas (2) and (1): + (t0) and DIC(t0); S342: Given CO2(t1) and Cmalk(t1) at t1, calculate DIC(t1) and H at t1 according to formula (7) + (t1), calculate Cmalk(t1) at t1 according to formula (2); DIC(t0)= DIC(t1)= CO2(t1)×(1+k'1 / H + (t1)+k'1k'2 / (H + (t1)^2)----(7) S343: Given Tsi(t0) at t0, DISi(t0) is obtained according to formula (16), Simalk(t0) is calculated according to formulas (17) and (18), DISi(t1) is calculated according to formulas (16)-(18) and (20), and the amount of colloidal silica precipitation is calculated according to formula (21); (DIsi(t0)-DIsi(t1))×1×50×1000=-(Cmalk(t0)+Simalk(t0))+(Cmalk(t1)+Simalk(t1))--(20) DISi =Tsi / 60 / 1000 --(16) <h2 style=";text-align:left;direction:ltr">Simalk=50000×(Si(OH)3O)<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> ) --(17) (Si(OH)3O - )=DISi / (1+H + / Ksi) --(18) Colloidal silicon precipitation amount SiO2 = (DISi(t0)-DISi(t1))×1×60×1000--(21) Wherein, DISi is the total dissolved inorganic silicon content mol / L, Tsi is the total dissolved inorganic silicon content mg / L, calculated as SiO2, Simalk is the alkalinity of inorganic silicon methyl orange mg / L, calculated as calcium carbonate, and Ksi is the dissociation constant of silicic acid; the unit of colloidal silicon precipitation SiO2 is mg / L.

6. The detection method according to claim 1, characterized in that: The step S2 includes: detecting the carbon dioxide gas concentration PCO2 in a closed detector, wherein a gas circulation pump and a gas phase carbon dioxide detector are provided in the loop of the closed detector, and the carbon dioxide gas concentration PCO2 is continuously recorded during the detection; and then the carbon dioxide gas concentration PCO2 is converted into the carbon dioxide concentration CO2w ​​in water according to Henry's law.

7. An electronic device, characterized in that: include: processor; A memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for detecting the precipitation rate of inorganic salts in water according to any one of claims 1 to 6 is implemented.

8. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the method for detecting the precipitation rate of inorganic salts in water according to any one of claims 1 to 6 is implemented.

9. A detection system for the precipitation rate of inorganic salts in water, characterized in that: It comprises a sealed detector for detecting carbon dioxide concentration and the electronic device according to claim 7, wherein the electronic device further comprises an input-output module, and the output end of the sealed detector is signal-connected to the input-output module of the electronic device.

10. The detection system according to claim 9, characterized in that: The closed detector includes a test container, a carbon dioxide detector, a first constant temperature heating unit and a gas circulation pump. The water to be tested is placed in the test container. The inlet of the carbon dioxide detector is connected to the test container. The outlet of the carbon dioxide detector is connected to the test container through the gas circulation pump to form a pipeline loop for the circulation of carbon dioxide. The first constant temperature heating unit is arranged on the test container to control the temperature of the test water to be in a constant temperature state.

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