Polyacrylic acid dispersant content on-line detection method and device

Abstract

The present application relates to the field of online detection, and more particularly to a polyacrylic acid dispersant content online detection method and device. The device comprises: a water sample sampling pipeline and a standard solution storage bottle are connected to different inlets of a multi-position selection valve; a first control valve, a filter and a stop valve are sequentially arranged on the water sample sampling pipeline; an outlet of the multi-position selection valve and an eluent inlet pipe are connected to a multi-channel sampling valve; a second control valve and a degassing device are sequentially arranged on the eluent inlet pipe; a sampler is arranged between the standard solution storage bottle and the multi-position selection valve; a sampling pump is arranged between the multi-position selection valve and the multi-channel sampling valve; a quantitative ring is arranged in the multi-channel sampling valve, one channel of which is connected to a waste liquid discharge pipe; an outlet of the multi-channel sampling valve is sequentially connected to a guard column, a gel permeation chromatography size exclusion column, a self-regeneration ion suppressor and a UV detector; and a computer is connected to the UV detector. The method comprises: drawing a standard curve; and using the device to detect samples. The present application has the advantages of fast response speed, high detection precision, sensitive detection limit, high degree of automation and the like, can realize real-time monitoring and detection of polyacrylic acid dispersants, reduces manual operation and reduces the workload of nuclear power plant operators.

Description

Technical Field

[0001] This invention relates to the field of online detection, and in particular to a method and apparatus for online detection of polyacrylic acid dispersant content. Background Technology

[0002] Pressurized water reactor nuclear power plants typically employ two measures to minimize deposits on the inner surface of the steam generator (SG): source term control and end-of-pipe cleaning. The former aims to reduce the amount of corrosion products entering the steam generator feedwater, while the latter removes existing deposits from the steam generator using chemical or mechanical means during unit shutdowns and overhauls, such as chemical cleaning and hydraulic flushing.

[0003] Since the 1990s, the international nuclear power field has gradually developed a third control measure: dispersant fouling control technology. This involves adding polyacrylic acid dispersants online into the steam generator feedwater system. By slowing the settling rate of corrosion product particles, these particles remain suspended in the liquid for a certain period and are ultimately discharged quickly and directly through the steam generator blowdown system. This technology is an intervention measure for the deposition of corrosion products entering the steam generator during the power operation of the nuclear power unit, and it faces a relatively harsh application environment of high temperature, high pressure, and high flow rate. Therefore, before applying the dispersant, its compatibility with the steam generator structural materials and internal components, as well as its impact on the chemical indicators of the secondary loop water, such as the iron content of the steam generator feedwater, the conductivity and pH of the steam generator blowdown water, must be strictly reviewed to ensure the normal and safe operation of the steam generator. During full-power operation of nuclear power units, the amount of dispersant added online directly affects the above-mentioned results. Therefore, in the nuclear power field, the final feedwater concentration of polyacrylic acid (PAA) dispersant continuously added online is kept to a very low level (reaching the ppb level), and the concentration of PAA in the steam generator needs to be monitored in real time to ensure that it is controlled below the limit of 1 ppm.

[0004] Currently, there are no publicly available online monitoring methods for polyacrylic acid content in China. Among the only offline detection methods, the polyacrylic acid content determination method (such as GB / T 14421 1993 Boiler Water and Cooling Water Analysis Methods - Determination of Polyacrylic Acid by Turbidimetric Method) has a measurement range and minimum detection concentration of 0–50 mg / L and 0.5 mg / L, respectively. Moreover, the allowable error for low concentration detection is relatively large (0.14 mg / L). Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an online detection method and device for polyacrylic acid dispersant content, which has the advantages of fast response speed, high detection accuracy, sensitive detection limit and high degree of automation. It can realize real-time monitoring and detection of polyacrylic acid dispersant, reduce manual operation and reduce the workload of nuclear power plant operators.

[0006] This invention provides an online detection device for polyacrylic acid dispersant content, comprising:

[0007] The water sample collection pipeline and the standard solution storage bottle are respectively connected to different inlets of a multi-position selector valve;

[0008] The water sampling pipeline is sequentially equipped with a first control valve, a filter, and a shut-off valve.

[0009] The outlet of the multi-position selector valve and the eluent inlet pipe are connected to a multi-channel injection valve;

[0010] A second control valve and a degassing device are sequentially installed on the rinsing solution inlet pipe;

[0011] An injector is installed between the standard solution storage bottle and the multi-position selector valve;

[0012] A sampling pump is installed between the multi-position selector valve and the multi-channel injection valve;

[0013] The multi-channel injection valve is equipped with a quantitative loop, one of which is connected to the waste liquid discharge pipe;

[0014] The outlet of the multi-channel injection valve is sequentially connected to a guard column, a gel permeation chromatography volume exclusion column, a self-regenerating ion suppressor, and an ultraviolet detector.

[0015] The computer is connected to the ultraviolet detector.

[0016] In one specific embodiment of the present invention, the standard solution storage bottle is placed inside a temperature-controlled box.

[0017] In one specific embodiment of the present invention, the protective column and the gel permeation chromatography size exclusion column are disposed inside a column oven.

[0018] In one specific embodiment of the present invention, an eluent delivery pump is provided between the degassing device and the multi-channel injection valve.

[0019] This invention provides an online detection method for polyacrylic acid dispersant content using the device described above, comprising the following steps:

[0020] Step 1: Prepare a standard solution and use it for injection to balance the fluid system within the entire apparatus;

[0021] The multi-channel injection valve is switched to connect the eluent delivery pump to the quantitative loop. The eluent delivery pump sends the eluent into the multi-channel injection valve, so that the liquid stored in the quantitative loop flows through the guard column and the gel permeation chromatography volume exclusion column, is separated by the chromatographic column, and then flows into the self-regenerating ion suppressor and the ultraviolet detector for detection and analysis.

[0022] Plot the standard curve;

[0023] Step 2: After filtering the water sample, inject the sample to balance the fluid system within the entire device;

[0024] The multi-channel injection valve is switched to connect the eluent delivery pump to the quantitative loop. The eluent delivery pump delivers the eluent into the multi-channel injection valve, allowing the liquid stored in the quantitative loop to flow through the guard column and the gel permeation chromatography volume exclusion column. After separation by the chromatographic column, the liquid flows into the self-regenerating ion suppressor and the ultraviolet detector for detection and analysis. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35℃, and the column pressure is 2–2.5 MPa.

[0025] In a specific embodiment of the present invention, the method for balancing the fluid system within the entire device by introducing a standard solution in step 1 is as follows:

[0026] The injector delivers the standard solution through a multi-position selector valve and a sampling pump into a multi-channel injection valve. The standard solution is stored in a quantitative loop and then discharged from the waste liquid drain pipe. The eluent delivery pump delivers the eluent into the multi-channel injection valve, which flows through the guard column, gel permeation chromatography volume exclusion column, self-regenerating ion suppressor, and ultraviolet detector to balance the fluid system within the device.

[0027] The standard solution injection flow rate is in the range of 1–50 mL / min;

[0028] The eluent flow rate is in the range of 0.2 to 2 mL / min, the column temperature is 25 to 35 °C, and the column pressure is 2 to 2.5 MPa.

[0029] In one specific embodiment of the present invention, the concentrations of the standard solutions are 10 μg / L, 50 μg / L, 200 μg / L, 500 μg / L, and 1000 μg / L, and they are stored at 4°C in a temperature-controlled chamber.

[0030] In a specific embodiment of the present invention, the specific method for injecting the water sample after filtration in step 2 is as follows:

[0031] The water sample flows through the water sample sampling pipe and the first control valve, and then through the filter to remove particulate matter. The filtered water sample flows through the shut-off valve and the multi-position selection valve, and is then delivered by the sampling pump. The water sample is stored in the quantitative loop and then discharged from the waste liquid drain pipe. The eluent delivery pump sends the eluent into the multi-channel injection valve, and then through the guard column, the gel permeation chromatography volume exclusion column, the self-regenerating ion suppressor, and the ultraviolet detector to balance the system.

[0032] In one specific embodiment of the present invention, in step 2, the water sample flow rate is between 1 and 50 mL / min.

[0033] In one specific embodiment of the present invention, step 3 is also included: spike recovery rate and repeatability test;

[0034] Specifically, it includes:

[0035] Using polyacrylic acid standard solution as the analytical sample, and the aforementioned background solution as the solvent, spiked samples with theoretical polyacrylic acid contents of 33 ppb, 100 ppb, and 100 ppb were prepared. The samples were then analyzed by online chromatography using the aforementioned device, and the spiked recoveries were calculated.

[0036] A polyacrylic acid standard solution with a peak molecular weight Mp of 62900 was used as the analytical sample. High-purity water was used as the solvent to prepare a spiked sample with a theoretical PAA content of 50 ppb. Repeatability test rate.

[0037] Compared with the prior art, the online detection method and apparatus for polyacrylic acid dispersant content of the present invention has the following beneficial effects:

[0038] (1) It can continuously monitor the concentration of polyacrylic acid dispersant in the secondary loop water, especially the trace detection when the dispersant is continuously added during the operation of the unit.

[0039] (2) The response time of the sample is <30min and the analysis frequency can be controlled independently. Compared with offline detection, it solves the problems of high labor cost, many intermediate links, long time consumption and human judgment deviation. Attached Figure Description

[0040] Figure 1 A schematic diagram showing the structure of an online detection device for polyacrylic acid dispersant content;

[0041] Figure 2 This image shows the results of sample testing.

[0042] In the diagram, 1-water sample sampling pipe, 2-first control valve, 3-filter, 4-stop valve, 5-multi-position selector valve, 6-temperature control chamber, 7-standard solution storage bottle, 8-injector, 9-sampling pump, 10-waste liquid drain pipe, 11-multi-channel injection valve, 12-eluent inlet pipe, 13-second control valve, 14-degassing device, 15-eluent delivery pump, 16-quantitative loop, 17-guard column, 18-gel permeation chromatography volume exclusion column, 19-column oven, 20-self-regenerating ion suppressor, 21-ultraviolet detector, 22-computer, 23-drain pipe. Detailed Implementation

[0043] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0044] An embodiment of the present invention discloses an online detection device for polyacrylic acid dispersant content, such as... Figure 1 As shown, it includes:

[0045] The water sample collection pipeline 1 and the standard solution storage bottle 7 are respectively connected to different inlets of the multi-position selector valve 5;

[0046] The standard solution storage bottle 7 is placed inside the temperature control box 6 to maintain a constant temperature of the standard solution;

[0047] A first control valve 2, a filter 3, and a shut-off valve 4 are sequentially installed on the water sample sampling pipeline 1;

[0048] The outlet of the multi-position selector valve 5 and the eluent inlet pipe 12 are connected to the multi-channel sample injection valve 11;

[0049] A second control valve 13, a degassing device 14, and a rinsing liquid transfer pump 15 are sequentially installed on the rinsing liquid inlet pipe 12.

[0050] An injector 8 is installed between the standard solution storage bottle 7 and the multi-position selector valve 5;

[0051] A sampling pump 9 is installed between the multi-position selector valve 5 and the multi-channel injection valve 11;

[0052] A quantitative ring 16 is provided inside the multi-channel injection valve 11, and one of its channels is connected to the waste liquid discharge pipe 10;

[0053] The outlet of the multi-channel injection valve 11 is sequentially connected to a guard column 17, a gel permeation chromatography volume exclusion column 18, a self-regenerating ion suppressor 20, and an ultraviolet detector 21.

[0054] The protective column 17 and the gel permeation chromatography size exclusion column 18 are disposed inside the column oven 19;

[0055] Computer 22 is connected to ultraviolet detector 21.

[0056] Among them, the sampling pump 9, the eluent transfer pump 15 and the pipeline are made of polyether ether ketone (PEEK) material to avoid metal contamination, and can withstand high pressure, acid and alkali and organic phase corrosion.

[0057] Functions of main components:

[0058] a) Filter 3: The filter pore size can be selected from 0.2 to 1 μm, and its function is to remove insoluble particulate matter in water.

[0059] b) Multi-position selector valve 5: By switching the connection with the shut-off valve 4 or the injector 8 through the multi-position selector valve 5, the injection of water samples and standard solutions can be switched.

[0060] c) Multi-channel injection valve: The multi-channel injection valve 11 switches the connection between the quantitative loop 16 and the sampling pump 9 or the eluent delivery pump 15, thereby switching between the injection and analysis processes. The implementation is as follows: when the quantitative loop 16 is connected to the sampling pump 9, it is in the sample injection process; when switched to connecting the quantitative loop 16 to the eluent delivery pump 15, it is in the sample analysis process.

[0061] d) Degassing device 14: Its main function is to degas the eluent online to prevent bubbles or leakage in the pipeline and pump, avoid CO2 intrusion from the air, and reduce baseline noise and disordered chromatographic peaks.

[0062] e) Gel permeation chromatography size exclusion column 18: When the sample enters the gel permeation chromatography size exclusion column, molecules larger than the size of the gel pores flow through the gaps between the gel particles, while molecules smaller than the size of the gel pores enter the gel pores and diffuse in the gaps between the gel pores and the particles. Therefore, large molecules have a shorter residence time in the column and are preferentially eluted, while small molecules have a longer residence time, thus achieving the separation of molecules of different volumes.

[0063] f) UV detector 21: PAA solution has the maximum absorption value in the UV region, and there is a clear and stable detection signal on UV detector 21. It is less affected by other substances in the background solution, so UV detector 21 is selected for detection.

[0064] When in sample injection mode, the liquid sample enters the multi-port injection valve 11 through the outlet of the sampling pump 9, flows through the metering loop 16, and the excess liquid sample flows out through the waste liquid drain pipe 10.

[0065] When in detection mode, the multi-channel injection valve 11 rotates, connecting the eluent delivery pump 15 to the quantitative loop 16. The eluent delivery pump 15 sends the eluent into the multi-channel injection valve 11, allowing the liquid stored in the quantitative loop 16 to flow through the guard column 17 and the gel permeation chromatography volume exclusion column 18, be separated by the chromatographic column, and then flow into the waste liquid tube at the other end of the self-regenerating ion suppressor 20 and the ultraviolet detector 21 for discharge.

[0066] Embodiments of the present invention also disclose an online detection method for polyacrylic acid dispersant content using the device described above, comprising the following steps:

[0067] Step 1: Plotting the standard curve, specifically including:

[0068] Step 1-1: Preparation of standard solution;

[0069] The standard solutions had concentrations of 10 μg / L, 50 μg / L, 200 μg / L, 500 μg / L, and 1000 μg / L, and were stored at 4°C in a temperature-controlled chamber 6.

[0070] Steps 1-2: Injection of standard solution;

[0071] Specifically, the injector 8 sends the standard solution into the multi-channel injection valve 11 via the multi-position selection valve 5 and the sampling pump 9, with the standard solution injection flow rate in the range of 1 to 50 mL / min.

[0072] The standard solution is stored in the quantitative loop 16 and then discharged from the waste liquid drain pipe 10; the eluent delivery pump 15 sends the eluent into the multi-channel injection valve 11, which flows through the guard column 17, the gel permeation chromatography volume exclusion column 18, the self-regenerating ion suppressor 20, and the ultraviolet detector 21 to balance the fluid system in the device.

[0073] The eluent flow rate is in the range of 0.2 to 2 mL / min, the column temperature is 25 to 35 °C, and the column pressure is 2 to 2.5 MPa.

[0074] Steps 1-3: Elution analysis;

[0075] Specifically:

[0076] The multi-channel injection valve 11 is switched to connect the eluent delivery pump 15 to the quantitative loop 16. The eluent delivery pump 15 sends the eluent into the multi-channel injection valve 11, so that the liquid stored in the quantitative loop 16 flows through the guard column 17 and the gel permeation chromatography volume exclusion column 18, is separated by the chromatographic column, and then flows into the self-regenerating ion suppressor 20 and the ultraviolet detector 21 for detection and analysis.

[0077] The eluent flow rate is in the range of 0.2 to 2 mL / min, the column temperature is 25 to 35 °C, and the column pressure is 2 to 2.5 MPa.

[0078] Steps 1-4: Plot the standard curve;

[0079] Under the stable and optimal operating conditions of the device, a series of standard solutions were tested, and the peak positions and peak integral area values ​​of each chromatogram were recorded. A standard curve was plotted with concentration on the x-axis and peak integral area values ​​on the y-axis.

[0080] Step 2: Online sample testing, specifically including:

[0081] Step 2-1: Sample injection;

[0082] Specifically: the water sample flows through the water sample sampling pipe 1 and the first control valve 2, and then through the filter 3 to remove particulate matter; the filtered water sample flows through the shut-off valve 4 and the multi-position selection valve 5, and is delivered by the sampling pump 9 at a flow rate of 1-50 mL / min; the water sample is stored in the quantitative loop 16 and then discharged from the waste liquid drain pipe 10; the eluent delivery pump 15 sends the eluent into the multi-channel injection valve 11, and flows through the guard column 17, the gel permeation chromatography volume exclusion column 18, the self-regenerating ion suppressor 20, and the ultraviolet detector 21 to balance the system.

[0083] The eluent flow rate is in the range of 0.2 to 2 mL / min, the column temperature is 25 to 35 °C, and the column pressure is 2 to 2.5 MPa.

[0084] Step 2-2: Elution analysis;

[0085] Specifically, the multi-channel injection valve 11 is switched to connect the eluent delivery pump 15 to the quantitative loop 16. The eluent delivery pump 15 delivers the eluent into the multi-channel injection valve 11, allowing the liquid stored in the quantitative loop 16 to flow through the guard column 17 and the gel permeation chromatography size exclusion column 18. Separation occurs through the chromatographic column, and the eluent then flows into the self-regenerating ion suppressor 20 and the ultraviolet detector 21 for detection and analysis. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35℃, and the column pressure is 2–2.5 MPa.

[0086] Steps 2-3: Test Result Analysis;

[0087] Water samples were tested online at regular intervals. The peak positions on the chromatograms were compared and the integrated area of ​​the signal peaks was recorded. The content of polyacrylic acid in the unknown water sample was determined by the standard curve.

[0088] Step 3: Spike recovery and repeatability testing, specifically including:

[0089] Using polyacrylic acid standard solution as the analytical sample, and the aforementioned background solution as the solvent, spiked samples with theoretical polyacrylic acid contents of 33 ppb, 100 ppb, and 100 ppb were prepared. The samples were then analyzed by online chromatography using the aforementioned device, and the spiked recoveries were calculated.

[0090] A polyacrylic acid standard solution with a peak molecular weight Mp of 62900 was used as the analytical sample. High-purity water was used as the solvent to prepare a spiked sample with a theoretical PAA content of 50 ppb. Repeatability test rate.

[0091] To further understand the present invention, the online detection method and apparatus for polyacrylic acid dispersant content provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0092] Example 1

[0093] The water sample sampling pipeline 1 is connected to one end of the first control valve 2. The other end of the first control valve 2 is connected to the filter device 3. The filter device 3 is connected to the inlet 1 of the multi-position selector valve 5 after passing through the shut-off valve 4. The multiple inlets of the multi-position selector valve 5 are respectively connected to the standard solution storage bottle 7. The outlet of the multi-position selector valve 5 is connected to the sampling pump 9.

[0094] In injection mode, the liquid sample enters the multi-port injection valve 11 through the outlet of the sampling pump 9, flows through the quantitative loop 16, and then flows out through the waste liquid drain pipe 10. In detection mode, the multi-port injection valve 11 rotates. In this mode, the liquid sample enters the multi-port injection valve 11 through the outlet of the sampling pump 9 and flows directly out through the waste liquid drain pipe 10. The ultrapure water eluent flows through the degassing device 14 and the eluent transfer pump 15 into the multi-port injection valve 11, flows through the quantitative loop 16, and then flows from the outlet of the multi-port injection valve 11 into the guard column 17, and then into the gel permeation chromatography size exclusion column 18. The liquid flowing out of the gel permeation chromatography size exclusion column 18 enters the self-regenerating ion suppressor 20, then flows into the ultraviolet detector 21, and is discharged through the waste liquid pipe at the other end of the ultraviolet detector 21.

[0095] Example 2

[0096] (1) Plotting the standard curve

[0097] a) Standard solution preparation process:

[0098] Prepare a mixed solution of 5 mg / L ethanolamine and 100 μg / L hydrazine using high-purity water as the background solution. Accurately weigh 0.1 g of polyacrylic acid (PAA) standard sample into a 100 mL glass volumetric flask, dilute to the mark with the background solution, and mix well to obtain a 1 g / L polyacrylic acid stock solution, which should be stored at 4°C for later use. Accurately dilute a certain amount of the polyacrylic acid stock solution with high-purity water to prepare standard solutions of 10, 50, 200, 500, and 1000 μg / L, place them in standard solution storage bottles 7, and store them in a temperature-controlled incubator 6 at 4°C.

[0099] b) Standard solution injection process:

[0100] The injector 8 delivers the standard solution through the multi-position selector valve 5 and the sampling pump 9 into the multi-channel injection valve 11. The standard solution injection flow rate is in the range of 1–50 mL / min. The standard solution is stored in the quantitative loop 16 and then discharged from the waste liquid drain pipe 10. The eluent delivery pump 15 delivers the eluent into the multi-channel injection valve 11, which flows through the guard column 17, the gel permeation chromatography size exclusion column 18, the self-regenerating ion suppressor 20, and the ultraviolet detector 21 to equilibrate the system. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35 °C, and the column pressure is 2–2.5 MPa.

[0101] c) Elution analysis process:

[0102] The six-channel injection valve (11) is switched to connect the eluent delivery pump (15) to the quantitative loop (16). The eluent delivery pump (15) delivers the eluent into the six-channel injection valve (11), allowing the liquid stored in the quantitative loop to flow through the guard column (17), the gel permeation chromatography size exclusion column (18), and be separated by the chromatographic column (18). The eluent then flows into the self-regenerating ion suppressor (20) and the ultraviolet detector (21) for detection and analysis. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35 °C, and the column pressure is 2–2.5 MPa.

[0103] d) Standard curve plotting process:

[0104] Connect the power supply and adjust the instrument to its optimal working condition. Preheat the instrument for at least 1 hour to stabilize the baseline. Under optimal instrument conditions, test a series of standard solutions and record the peak position and peak integrated area of ​​each chromatogram. Plot a standard curve with concentration on the x-axis and peak integrated area on the y-axis.

[0105] (2) Sample online testing process

[0106] a) Sample injection process:

[0107] The water sample flows through the water sample sampling tube 1 and the first control valve 2, then through the filter 3 to remove particulate matter. The filtered water sample flows through the shut-off valve 4 and the multi-position selection valve 5, and is then delivered by the sampling pump 9 at a flow rate of 1–50 mL / min. The water sample is stored in the quantitative loop 16 and then discharged from the waste liquid drain pipe 10. The eluent delivery pump 15 delivers the eluent to the six-channel injection valve 11, which then flows through the guard column 17, the gel permeation chromatography size exclusion column 18, the self-regenerating ion suppressor 20, and the ultraviolet detector 21 to equilibrate the system. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35℃, and the column pressure is 2–2.5 MPa.

[0108] b) Elution analysis process:

[0109] The multi-channel injection valve 11 is switched to connect the eluent delivery pump 15 to the quantitative loop 16. The eluent delivery pump 15 delivers the eluent into the multi-channel injection valve 11, allowing the liquid stored in the quantitative loop to flow through the guard column 17 and the gel permeation chromatography size exclusion column 18. Separation occurs through the column 18, and the eluent then flows into the self-regenerating ion suppressor 20 and the ultraviolet detector 21 for detection and analysis. The eluent flow rate is in the range of 0.2–2 mL / min, the column temperature is 25–35 °C, and the column pressure is 2–2.5 MPa.

[0110] c) Test Result Analysis

[0111] Water samples were tested online at regular intervals. The peak positions on the chromatograms were compared and the integrated area of ​​the signal peaks was recorded. The content of polyacrylic acid in the unknown water sample was determined by the standard curve. Figure 2 The results of testing PAA using this method are shown in Table 1 below.

[0112] Table 1 Example of measurement results

[0113]

[0114] (3) Spike recovery rate and repeatability test

[0115] Using PAA standard solution as the analytical sample, spiked samples with theoretical PAA contents of 33 ppb, 100 ppb, and 100 ppb were prepared using the aforementioned background solution as the solvent. The peak molecular weights (Mp) of the three PAA standards used were 1550, 28000, and 130500, respectively. The online chromatographic detection method described above is shown in Table 2, and the average recovery rate was 99.5%.

[0116] Table 2 Results of Spiked Recovery Test

[0117] Serial Number Theoretical value (ppb) Test value (ppb) Recovery rate (%) Remark 1 33 32.835 99.5 MP 1900 2 100 99.418 99.4 MP 28000 3 100 99.633 99.6 MP 130500

[0118] PAA (peak molecular weight Mp 62900) standard solution was used as the analytical sample. High-purity water was used as the solvent to prepare a spiked sample with a theoretical PAA content of 50 ppb. The results of the repeated test 7 times are shown in Table 3. The average recovery rate was 99.3%.

[0119] Table 3 Results of Repeated Tests and Spiked Recovery Tests

[0120] Serial Number Theoretical value (ppb) Test value (ppb) Recovery rate (%) 1 50 50.420 100.8 2 50 49.358 98.7 3 50 48.261 96.5 4 50 49.366 98.7 5 50 49.295 98.6 6 50 50.933 101.9

[0121] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An online detection device for polyacrylic acid dispersant content, characterized in that, include: The water sample collection pipeline and the standard solution storage bottle are respectively connected to different inlets of a multi-position selector valve; The water sampling pipeline is sequentially equipped with a first control valve, a filter, and a shut-off valve. The outlet of the multi-position selector valve and the eluent inlet pipe are connected to a multi-channel injection valve; A second control valve and a degassing device are sequentially installed on the rinsing solution inlet pipe; An injector is installed between the standard solution storage bottle and the multi-position selector valve; the standard solution storage bottle is installed in a temperature control chamber; the guard column and the gel permeation chromatography size exclusion column are installed in a column oven; A sampling pump is installed between the multi-position selector valve and the multi-channel injection valve; A quantitative loop is installed inside the multi-channel injection valve, and one of the channels of the multi-channel injection valve is connected to the waste liquid discharge pipe; The outlet of the multi-channel injection valve is sequentially connected to a guard column, a gel permeation chromatography volume exclusion column, a self-regenerating ion suppressor, and an ultraviolet detector. The computer is connected to the ultraviolet detector; A rinsing fluid delivery pump is installed between the degassing device and the multi-channel injection valve.

2. A method for online detection of polyacrylic acid dispersant content using the device described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare a standard solution and use it for liquid injection to balance the fluid system within the entire device; The multi-channel injection valve is switched to connect the eluent delivery pump to the quantitative loop. The eluent delivery pump sends the eluent into the multi-channel injection valve, so that the liquid stored in the quantitative loop flows through the guard column and the gel permeation chromatography volume exclusion column, is separated by the chromatographic column, and then flows into the self-regenerating ion suppressor and the ultraviolet detector for detection and analysis. A standard curve is plotted based on the data from the test and analysis. Step 2: After filtering the water sample, inject the sample to balance the fluid system within the entire device; The multi-channel injection valve is switched to connect the eluent delivery pump to the quantitative loop. The eluent delivery pump delivers the eluent into the multi-channel injection valve, allowing the liquid stored in the quantitative loop to flow through the guard column and the gel permeation chromatography volume exclusion column. After separation by the chromatographic column, the liquid flows into the self-regenerating ion suppressor and the ultraviolet detector for detection and analysis. The eluent flow rate is in the range of 0.2~2 mL / min, the column temperature is 25~35℃, and the column pressure is 2~2.5 MPa.

3. The online detection method for polyacrylic acid dispersant content according to claim 2, characterized in that, In step 1, the method of balancing the fluid system within the entire device by introducing a standard solution is as follows: The injector delivers the standard solution through a multi-position selector valve and a sampling pump into a multi-channel injection valve. The standard solution is stored in a quantitative loop and then discharged from the waste liquid drain pipe. The eluent delivery pump delivers the eluent into the multi-channel injection valve, which flows through the guard column, gel permeation chromatography volume exclusion column, self-regenerating ion suppressor, and ultraviolet detector to balance the fluid system within the device. The standard solution injection flow rate is in the range of 1~50 mL / min; The eluent flow rate is in the range of 0.2~2 mL / min, the column temperature is 25~35℃, and the column pressure is 2~2.5 MPa.

4. The online detection method for polyacrylic acid dispersant content according to claim 2, characterized in that, The standard solutions had concentrations of 10 μg / L, 50 μg / L, 200 μg / L, 500 μg / L, and 1000 μg / L, and were stored at 4°C in a temperature-controlled chamber.

5. The online detection method for polyacrylic acid dispersant content according to claim 2, characterized in that, In step 2, the specific method for injecting the water sample after filtration is as follows: The water sample flows through the water sample sampling pipe and the first control valve, and then through the filter to remove particulate matter. The filtered water sample flows through the shut-off valve and the multi-position selection valve, and is then delivered by the sampling pump. The water sample is stored in the quantitative loop and then discharged from the waste liquid drain pipe. The eluent delivery pump sends the eluent into the multi-channel injection valve, and then through the guard column, the gel permeation chromatography volume exclusion column, the self-regenerating ion suppressor, and the ultraviolet detector to balance the system.

6. The online detection method for polyacrylic acid dispersant content according to claim 5, characterized in that, In step 2, the water sample flow rate is 1~50 mL / min.

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