System and method for measuring silicate radicals in high-purity water through on-line ion chromatography and application

Abstract

The invention discloses a system and a method for measuring silicate radicals in high-purity water by on-line ion chromatography and application, the system realizes automatic on-line enrichment of trace silicate radicals (such as 1-5ppb in steam condensation water) by integrating an intelligent concentration unit and switching a flow path by using a multi-port high-pressure valve. For a high-concentration sample (such as 100-500ppb in boiler water), the system can directly analyze by bypassing a concentration column. The method comprises the following steps: sample introduction, automatic flow path judgment and switching based on concentration, fixed volume concentration and elution of trace samples, ion chromatography separation, suppressed conductivity detection and data processing. The method solves the problem that ppb-grade silicate cannot be detected on line by a traditional method, realizes full-scale, high-precision and low-maintenance on-line monitoring from ppb to thousands of ppb, and is particularly suitable for water quality control of high-purity water systems in electric power, petroleum and chemical industries.

Description

Technical Field

[0001] This invention relates to the fields of analytical chemistry and water quality monitoring technology, specifically to a system, method, and application for online ion chromatography to measure silicate in high-purity water. Background Technology

[0002] Silicate (SiO3) 2- Silicate is a crucial monitoring indicator in steam-water systems. In high-temperature, high-pressure boilers, excessive silicate ions precipitate with the steam, forming hard silicate scale on turbine blades and heat exchange surfaces, severely reducing thermal efficiency and threatening equipment safety. Therefore, strict monitoring of silicate ions in boiler feedwater, boiler water, and steam condensate is essential.

[0003] Currently, online measurement of silicate ions mainly employs spectrophotometry (molybdenum blue method). This method has the following inherent drawbacks: 1) Frequent preparation and consumption of chemical reagents (molybdate, reducing agent, etc.) are required, resulting in high operating costs and secondary pollution; 2) The reaction is easily affected by substances such as phosphate and iron ions in the water, leading to measurement errors; 3) Pipelines and flow cells are easily blocked due to reagent crystallization or precipitation, requiring a large amount of maintenance; 4) It is difficult to achieve truly continuous measurement, and is usually intermittent, lacking real-time capability.

[0004] Ion chromatography (IC) is a standard method for determining anions, offering advantages such as high selectivity, high precision, and the elimination of the need for complex colorimetric reagents. However, applying it to online monitoring of trace silicates in high-purity water faces significant challenges. For boiler water (100-500 ppb), while direct injection is possible, dedicated online equipment is lacking. For ultrapure steam condensate (1-5 ppb), its concentration is below the conductivity detection limit of conventional ion chromatography, resulting in weak or indistinct chromatographic peaks, making direct and accurate quantification impossible.

[0005] Therefore, there is an urgent need in this field for a new method and system that can achieve full-range, high-precision, low-reagent, and online real-time monitoring of silicate ions. Summary of the Invention

[0006] The purpose of this invention is to provide a system, method, and application for online ion chromatography to measure silicate in high-purity water, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A system for online ion chromatography to measure silicate in high-purity water includes: The sample introduction and switching module is used to automatically select and introduce water samples from different sources; The intelligent concentration and separation module includes a multi-port high-pressure switching valve, a concentration column, and an analytical column. The concentration column is filled with anion exchange resin that has high selectivity for silicate. The high-pressure switching valve can be switched to allow sample water to flow through the concentration column to achieve silicate adsorption and enrichment, or to allow eluent to flow through the concentration column to achieve silicate elution and enter the analytical column for separation. The detection and data processing module, including a suppressor, a conductivity detector, and a control unit, is used to detect the separated silicate ions and calculate their concentration. The automatic control and communication module is used to coordinate the operation of various modules in the system according to a predetermined program and to output data.

[0008] As a further aspect of the present invention: the sample introduction and switching module includes a multi-channel selection valve, a sampling pump and an online filter, for automatically switching and collecting boiler water samples and steam condensate samples, and performing pretreatment.

[0009] As a further aspect of the present invention: the suppressor is used to reduce background conductivity, the conductivity detector is used to detect the separated silicate ions, and the control unit integrates control software for automatically controlling the entire process, collecting data, and automatically calculating and outputting the silicate concentration value based on the calibration curve.

[0010] As a further aspect of the present invention: the automatic control and communication module includes controlling the opening, closing and switching of pumps and valves according to a preset program or remote command, coordinating the concentration, elution, separation and detection processes, and uploading real-time data to the central control room.

[0011] As a further aspect of the present invention: the resin in the concentration column is a strongly basic anion exchange resin with a particle size of 5-15 μm and an exchange capacity of 20-100 μeq / column.

[0012] As a further aspect of the present invention: when eluting silicate from the concentration column, the flow direction of the eluent is opposite to the flow direction during sample enrichment.

[0013] A method for measuring silicate in high-purity water using any of the above-described systems, the method comprising the following steps: Determine the type of water sample. If it is a high-concentration silicate water sample, perform the direct injection analysis procedure. If it is a trace silicate water sample, perform the online concentration analysis procedure. The online concentration analysis process includes: a sample enrichment stage, in which the water sample to be tested flows through the concentration column at a set flow rate, silicate is adsorbed and retained, and waste liquid is discharged; and an elution and injection stage, in which the flow path is switched, the eluent is used to elute the silicate enriched on the concentration column and carry it into the analysis column. Suppression and conductivity detection of silicate ions flowing from the analytical column; Based on the peak area of ​​the detection signal, the original concentration of silicate in the water sample is calculated using the corresponding calibration curve.

[0014] As a further aspect of the present invention: for boiler water with an expected silicate concentration higher than 20 ppb, a direct injection analysis process is adopted; for steam condensate with an expected silicate concentration lower than 20 ppb, an online concentration analysis process is adopted.

[0015] As a further aspect of the present invention: the calibration curves include a high-concentration calibration curve for direct injection mode and a trace calibration curve for online concentration mode.

[0016] An application of any of the above methods in the power, petroleum, or chemical industries.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. Full-range measurement: Through its unique intelligent concentration and flow path switching design, a single system can cover a wide concentration range from ppb to thousands of ppb to meet the needs of different monitoring points.

[0018] 2. For steam condensate: Online automatic concentration technology is used to effectively enrich trace silicate ions, reducing the detection limit to 1 ppb, which solves the industry problem that traditional ion chromatography cannot detect ultra-low concentrations.

[0019] 3. Real-time and automation: The entire process (sampling, concentration, injection, separation, detection, and cleaning) is completed automatically, enabling a measurement frequency of at least once per hour, truly achieving online real-time monitoring.

[0020] 4. Low maintenance and high reliability: Compared with the molybdenum blue method, it does not require expensive chemical colorimetric reagents, avoiding pipeline blockage and interference problems, making the system more stable and the maintenance cycle longer.

[0021] 5. Strong anti-interference ability: The separation characteristics of ion chromatography can effectively eliminate the interference of common ions such as phosphate, making the measurement results more accurate and reliable. Attached Figure Description

[0022] Figure 1 This is a system block diagram of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure and principle of an online ion chromatography system.

[0024] Figure 2-A for Figure 2 Enlarged view of a portion of point A in the middle.

[0025] Figure 2-B for Figure 2 Enlarged view of section B in the middle.

[0026] Figure 2-C for Figure 2 Enlarged view of a section at point C.

[0027] Figure 3 This is a flow path diagram of the system in "direct measurement mode" (for boiler water).

[0028] Figure 3-A for Figure 3 Enlarged view of a portion of point A in the middle.

[0029] Figure 3-B for Figure 3 Enlarged view of section B in the middle.

[0030] Figure 3-C for Figure 3 Enlarged view of a section at point C.

[0031] Figure 3-D for Figure 3 Enlarged view of a section at point D.

[0032] Figure 4 This is a flow path diagram of the system in the "sample enrichment" stage under "concentration mode".

[0033] Figure 4-A for Figure 4 Enlarged view of a portion of point A in the middle.

[0034] Figure 4-B for Figure 4 Enlarged view of section B in the middle.

[0035] Figure 4-C for Figure 4 Enlarged view of a section at point C.

[0036] Figure 4-D for Figure 4 Enlarged view of a section at point D.

[0037] Figure 5 This is a flow path diagram of the system during the "elution analysis" stage in "concentration mode".

[0038] Figure 5-A for Figure 5 Enlarged view of a portion of point A in the middle.

[0039] Figure 5-B for Figure 5 Enlarged view of section B in the middle.

[0040] Figure 5-C for Figure 5 Enlarged view of a section at point C.

[0041] Figure 5-D for Figure 5 Enlarged view of a section at point D. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Please refer to the attached figure for a system for online ion chromatography to measure silicate in high-purity water, which includes: The sample introduction and switching module is used to automatically select and introduce water samples from different sources, including a multi-channel selection valve sampling pump and an online filter, for automatically switching and collecting boiler water samples and steam condensate samples, and performing pretreatment. The intelligent concentration and separation module includes a multi-port high-pressure switching valve, a concentration column, and an analytical column. The concentration column is filled with anion exchange resin with high selectivity for silicates. The high-pressure switching valve can be switched to allow sample water to flow through the concentration column for silicate adsorption and enrichment, or to allow eluent to flow through the concentration column for silicate elution and separation into the analytical column. The two working flow paths of the high-pressure switching valve specifically include: a) Concentration Flow Path: When detecting steam condensate, the valve is switched to allow the sample water to flow through the concentration column, where silicate ions are selectively adsorbed and enriched, and the waste liquid is discharged.

[0047] b) Elution / Analysis Flow Path: After concentration, the valve is switched to allow the eluent to flow in reverse through the concentration column, rapidly eluting the enriched silicate ions and carrying them to the analytical column for separation.

[0048] For boiler water samples, the system can bypass the concentration column, allowing the sample to directly enter the analysis column.

[0049] The detection and data processing module includes a suppressor, a conductivity detector, and a control unit, used to detect the separated silicate ions and calculate their concentration; the suppressor is used to reduce background conductivity, and the conductivity detector is used to detect the separated silicate ions; the embedded control system integrates control software for automatically controlling the entire process, acquiring data, and automatically calculating and outputting the silicate concentration value based on the calibration curve.

[0050] The automatic control and communication module coordinates the operation of various modules in the system according to a predetermined program and outputs data. It uses a PLC or embedded microprocessor to control the opening, closing, and switching of pumps and valves according to a preset program or remote commands, coordinates the entire process of concentration, elution, separation, and detection, and uploads real-time data to the central control room via a 4-20mA, Modbus, or Ethernet interface.

[0051] The sample introduction and switching module includes a multi-channel selection valve, a sampling pump, and an online filter, used to automatically switch and collect boiler water samples and steam condensate samples, and to perform pretreatment.

[0052] The suppressor is used to reduce background conductivity, the conductivity detector is used to detect the separated silicate ions, and the control unit integrates control software to automatically control the entire process, collect data, and automatically calculate and output the silicate concentration value based on the calibration curve.

[0053] The resin in the concentration column is a strongly basic anion exchange resin with a particle size of 5-15 μm and an exchange capacity of 20-100 μeq / column.

[0054] When eluting silicate from the concentration column, the flow direction of the eluent is opposite to that during sample enrichment.

[0055] A method for measuring silicate in high-purity water using any of the above-described systems, the method comprising the following steps: Determine the type of water sample. If it is a high-concentration silicate water sample, perform the direct injection analysis procedure. If it is a trace silicate water sample, perform the online concentration analysis procedure. The online concentration analysis process includes: a sample enrichment stage, in which the water sample to be tested flows through the concentration column at a set flow rate, silicate is adsorbed and retained, and waste liquid is discharged; and an elution and injection stage, in which the flow path is switched, the eluent is used to elute the silicate enriched on the concentration column and carry it into the analysis column. Suppression and conductivity detection of silicate ions flowing from the analytical column; Based on the peak area of ​​the detection signal, the original concentration of silicate in the water sample is calculated using the corresponding calibration curve.

[0056] For boiler water with an expected silicate concentration higher than 20 ppb, a direct injection analysis procedure is used; for steam condensate with an expected silicate concentration lower than 20 ppb, an online concentration analysis procedure is used.

[0057] For boiler water samples (high concentration mode): 1. Switch the system to direct injection mode; 2. After online filtration, the sample is quantitatively collected by a quantitative loop; 3. The sample is directly injected into the analytical flow path through a high-pressure switching valve and carried into the analytical column by the eluent for separation; 4. After the separated silicate groups pass through a suppressor, the peak area is detected by a conductivity detector, and the concentration is directly calculated.

[0058] For steam condensate samples (trace concentration mode) 1. The system switches to concentrated mode; 2. The sample is continuously passed through the concentration column at a constant flow rate (e.g., 2-5 mL / min) for a period of time (e.g., 2-5 minutes) to achieve a fixed volume concentration of 5-20 times. During this period, silicate ions are adsorbed by the resin, and high-purity water is discharged as waste liquid. 3. At the end of the concentration stage, the high-pressure switching valve automatically switches; 4. A high-concentration eluent (e.g., a 50-100 mM sodium carbonate / sodium bicarbonate solution) is pumped in and flows in the reverse direction through the concentration column, rapidly eluting the enriched silicate ions in the form of a small-volume concentration band. 5. This concentrated band is carried into the analytical column by the eluent, achieving chromatographic separation of silicate ions from other anions; 6. After separation, the silicate ions are suppressed, generating a significantly enhanced conductivity signal. The detector detects the peak area and the pre-established concentration mode calibration curve to calculate the original concentration in the sample. The detection limit can reach below 1 ppb.

[0059] The calibration curves include a high-concentration calibration curve for direct injection mode and a trace calibration curve for online concentration mode.

[0060] An application of any of the above methods in the power, petroleum, or chemical industries.

[0061] The specific implementation process includes the following parts: 1 System Construction Reference Figure 2 This system mainly consists of the following components: • The sampling pump (P1) and multi-channel selector valve (V1) take samples from the boiler water (SW) and steam condensate (SC) lines.

[0062] • A ten-way high-pressure automatic switching valve (V2) serves as the core Y for flow path control.

[0063] • A concentration column (CC) packed with anion exchange resin.

[0064] • One analytical column (AC) is model SX18.

[0065] • An electrolytically self-regenerating anion suppressor (SUP).

[0066] • A conductivity cell (CD) is used as a detector.

[0067] An embedded industrial computer acts as the control system, responsible for driving all components and processing data.

[0068] 2. Measurement of trace silicate in steam condensate ① Initialization: The control system starts up, and the eluent (20 mM KOHY automatically generated by EGC) flushes the entire analytical flow path. The system stabilizes. ② Concentration: Refer to Figure 4 V2 switches to the concentration position. Sampling pump P1 pumps steam condensate into the column at a flow rate of 3 mL / min for 3 minutes, totaling 9 mL of water sample passing through the concentration column (CC). Silicate ions are adsorbed, and the high-purity water waste liquid is discharged from Waste1. ③ Elution and injection: Refer to Figure 5 Concentration complete, V2 switch instantaneously. Eluent flow path changed, backwashing the concentration column (CC). Within approximately 30 seconds, the enriched silicate ions are eluted as a narrow band and injected into the analytical flow path. ④ Separation and Detection: This spectral band enters the analytical column (AC) with the eluent, and silicate ions are separated from other anions (such as Cl-). -、 SO4 2- After separation, the sample enters a suppressor (SUP) and is subsequently detected by a conductivity detector (CD). A silicate chromatographic peak with a high signal-to-noise ratio is obtained.

[0069] ⑤ Quantitative analysis: The control system compares the peak area with the "concentration mode" calibration curve established in advance using standard solutions, automatically calculates the true concentration of silicate in the sample, and outputs it through the communication interface.

[0070] 3. Measuring silicate in boiler water ①Mode switching: The control system selects the boiler water sample via V1.

[0071] ② Direct injection: Refer to Figure 3 The system uses a direct injection mode. The sample passes through a 5μL quantitative loop.

[0072] ③ Analysis: V2 remains in the analytical position, and the eluent carries the sample in the quantitative loop into the analytical column for separation and detection. The entire process requires no concentration step and is quick and simple.

[0073] The system and method described in this invention ingeniously solve the difficulty of online monitoring of silicate ions across the full concentration range in high-purity water through automated flow path control and concentration technology, and provides a pioneering solution for the real-time and accurate measurement of trace silicate ions at the ppb level in steam condensate.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for online ion chromatography to measure silicate ions in high-purity water, characterized in that, include: The sample introduction and switching module is used to automatically select and introduce water samples from different sources; The intelligent concentration and separation module includes a multi-port high-pressure switching valve, a concentration column, and an analytical column. The concentration column is filled with anion exchange resin that has high selectivity for silicate. The high-pressure switching valve can be switched to allow sample water to flow through the concentration column to achieve silicate adsorption and enrichment, or to allow eluent to flow through the concentration column to achieve silicate elution and enter the analytical column for separation. The detection and data processing module, including a suppressor, a conductivity detector, and a control unit, is used to detect the separated silicate ions and calculate their concentration. The automatic control and communication module is used to coordinate the operation of various modules in the system according to a predetermined program and to output data.

2. The system for online ion chromatography to measure silicate ions in high-purity water according to claim 1, characterized in that, The sample introduction and switching module includes a multi-channel selection valve, a sampling pump, and an online filter, used to automatically switch and collect boiler water samples and steam condensate samples, and to perform pretreatment.

3. The system for online ion chromatography to measure silicate ions in high-purity water according to claim 1, characterized in that, The suppressor is used to reduce background conductivity, the conductivity detector is used to detect the separated silicate ions, and the control unit integrates control software to automatically control the entire process, collect data, and automatically calculate and output the silicate concentration value based on the calibration curve.

4. The system for online ion chromatography to measure silicate ions in high-purity water according to claim 1, characterized in that, The automatic control and communication module includes functions such as controlling the opening, closing, and switching of pumps and valves according to preset programs or remote commands, coordinating the concentration, elution, separation, and detection processes, and uploading real-time data to the central control room.

5. The system for online ion chromatography to measure silicate in high-purity water according to claim 1, characterized in that, The resin in the concentration column is a strongly basic anion exchange resin with a particle size of 5-15 μm and an exchange capacity of 20-100 μeq / column.

6. The system for online ion chromatography to measure silicate in high-purity water according to claim 1, characterized in that, When eluting silicate from the concentration column, the flow direction of the eluent is opposite to that during sample enrichment.

7. A method for measuring silicate ions in high-purity water using the system described in any one of claims 1-5, characterized in that, The method includes the following steps: Determine the type of water sample. If it is a high-concentration silicate water sample, perform the direct injection analysis procedure. If it is a trace silicate water sample, perform the online concentration analysis procedure. The online concentration analysis process includes: a sample enrichment stage, in which the water sample to be tested flows through the concentration column at a set flow rate, silicate is adsorbed and retained, and waste liquid is discharged; and an elution and injection stage, in which the flow path is switched, the eluent is used to elute the silicate enriched on the concentration column and carry it into the analysis column. Suppression and conductivity detection of silicate ions flowing from the analytical column; Based on the peak area of ​​the detection signal, the original concentration of silicate in the water sample is calculated using the corresponding calibration curve.

8. The method for measuring silicate ions in high-purity water according to claim 7, characterized in that, For boiler water with an expected silicate concentration higher than 20 ppb, a direct injection analysis procedure is used; for steam condensate with an expected silicate concentration lower than 20 ppb, an online concentration analysis procedure is used.

9. The method for measuring silicate ions in high-purity water according to claim 7, characterized in that, The calibration curves include a high-concentration calibration curve for direct injection mode and a trace calibration curve for online concentration mode.

10. An application of the method according to any one of claims 7-9 in the power, petroleum, or chemical industries.

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