Online detection method and device for content of polyacrylic acid dispersant

Abstract

The invention relates to the field of on-line detection, in particular to an on-line detection method and device for the content of a polyacrylic acid dispersing agent. The device is characterized in that a water sampling pipeline and a standard solution storage bottle are respectively connected with different inlets of a multi-position selector valve; a first control valve, a filter and a stop valve are sequentially arranged on the water sampling pipeline; an outlet of the multi-position selection valve and the leacheate inlet pipe are connected with a multi-channel sample injection valve; a second control valve and a degassing device are sequentially arranged on the leacheate inlet pipe; a sample injector is arranged between the standard solution storage bottle and the multi-position selector valve; a sampling pump is arranged between the multi-position selection valve and the multi-channel sample injection valve; a quantitative loop is arranged in the multi-channel sample injection valve, and one channel is connected with a waste liquid discharge pipe; an outlet of the multi-channel sample injection valve is sequentially connected with a guard column, a gel permeation chromatography volume exclusion column, a self-regeneration ion suppressor and an ultraviolet detector; and the computer is connected with the ultraviolet detector. The method comprises the following steps: drawing a standard curve; the device is used for sample detection. The system has the advantages of high response speed, high detection precision, sensitive detection limit, high automation degree and the like, can realize real-time detection of the polyacrylic acid dispersant, reduces manual operation, and reduces the workload of nuclear power plant operators.

Description

Technical Field

[0001] The invention relates to the field of online detection, and in particular to an online detection method and device for polyacrylic acid dispersant content. Background Art

[0002] Pressurized water reactor nuclear power plants usually use two measures to minimize deposits on the inner surface of steam generators (SG): one measure is source control, and the other is end removal. The former aims to reduce the amount of corrosion products in the feed water entering the steam generator, while the latter uses chemical or mechanical means to remove existing deposits from the steam generator during the unit shutdown overhaul, such as chemical cleaning, hydraulic flushing, etc.

[0003] Since the 1990s, the international nuclear power field has gradually developed a third control measure, namely dispersant fouling control technology, which adds polyacrylic acid dispersant online to the steam generator feed water system, slows down the sedimentation rate of corrosion product particles, and keeps them suspended in the liquid for a certain period of time, and finally discharges them quickly and directly through the steam generator sewage 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 faces a relatively harsh application environment of high temperature, high pressure and high flow rate. Therefore, before the application of the dispersant, its compatibility with the structural materials and internal components of the steam generator, and its impact on the chemical indicators of the secondary circuit water, such as the iron content of the steam generator feed water, the conductivity and pH of the steam generator sewage, etc., need to be strictly examined to ensure the normal and safe operation of the steam generator. During the full-power operation of the nuclear power unit, the online addition amount of dispersant directly affects the above-mentioned impact results; therefore, in the nuclear power field, the final feed water concentration of the steam generator that controls the online continuous addition of polyacrylic acid (PAA) dispersant is extremely small (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 1ppm.

[0004] At present, there is no public online monitoring method 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 Method Polyacrylic Acid Determination Turbidimetric Method) has a measurement range and minimum detection concentration of 0-50 and 0.5 mg / L, and the allowable error of 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 a method and device for online detection of polyacrylic acid dispersant content, which has the advantages of fast response speed, high detection accuracy, sensitive detection limit, high degree of automation, etc., can realize real-time monitoring and detection of polyacrylic acid dispersant, reduce manual operation, and reduce the workload of nuclear power plant operators.

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

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

[0008] A first control valve, a filter and a stop valve are sequentially arranged on the water sampling pipeline;

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

[0010] A second control valve and a degassing device are sequentially arranged on the eluent inlet pipe;

[0011] A sample injector is arranged between the standard solution storage bottle and the multi-position selection valve;

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

[0013] A quantitative loop is arranged in the multi-channel injection valve, one of the channels of which is connected to a waste liquid discharge pipe;

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

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

[0016] In a specific embodiment of the present invention, the standard solution storage bottle is arranged in a temperature control box.

[0017] In a specific embodiment of the present invention, the guard column and the gel permeation chromatography size exclusion column are arranged in a column oven.

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

[0019] The present invention provides a method for online detection of polyacrylic acid dispersant content using the device described in the above technical solution, comprising the following steps:

[0020] Step 1: Prepare a standard solution, use the standard solution to fill the fluid, and balance the fluid system in the entire device;

[0021] The multi-channel injection valve is switched to connect the eluent delivery pump with the quantitative loop. The eluent delivery pump delivers 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 size 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] Draw a standard curve;

[0023] Step 2: After the water sample is filtered, it is injected to balance the fluid system in the entire device;

[0024] The multi-channel injection valve is switched to connect the eluent delivery pump with the quantitative loop. The eluent delivery pump delivers 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 size 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; the flow rate of the eluent 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.

[0025] In a specific embodiment of the present invention, in step 1, the method of using the standard liquid to carry out liquid inflow and balancing the fluid system in the entire device is:

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

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

[0028] The flow rate of the eluent 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 a 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, respectively, and are stored at 4° C. in a temperature-controlled box.

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

[0031] The water sample flows through the water sampling pipeline and the first control valve, and flows through the filter to remove particulate matter; the filtered water sample flows through the stop valve and the multi-position selection valve, and is transported 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, flows through the guard column, gel permeation chromatography size exclusion column, self-regenerating ion suppressor, and ultraviolet detector to balance the system.

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

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

[0034] Specifically include:

[0035] The polyacrylic acid standard solution was used as the analysis sample, and the background solution was used as the solvent to prepare spiked samples with theoretical polyacrylic acid contents of 33 ppb, 100 ppb, and 100 ppb, respectively. The device was used for online chromatographic detection, and the spiked recovery rate was calculated;

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

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

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

[0039] (2) The response time of the sample detection is less than 30 minutes, and the analysis frequency can be controlled independently. Compared with offline detection, it solves the problems of high labor costs, multiple intermediate links, long time consumption, and manual judgment bias. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 It represents the sample detection effect diagram;

[0042] In the figure, 1-water sample sampling pipeline, 2-first control valve, 3-filter, 4-stop valve, 5-multi-position selection valve, 6-temperature control box, 7-standard solution storage bottle, 8-injector, 9-sampling pump, 10-waste liquid discharge 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 size exclusion column, 19-column oven, 20-self-regenerating ion suppressor, 21-ultraviolet detector, 22-computer, 23-drainage pipeline. DETAILED DESCRIPTION

[0043] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

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

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

[0046] The standard solution storage bottle 7 is arranged in the temperature control box 6 to keep the temperature of the standard solution constant;

[0047] A first control valve 2, a filter 3 and a stop valve 4 are sequentially arranged on the water 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 injection valve 11;

[0049] The second control valve 13, the degassing device 14 and the eluent delivery pump 15 are sequentially arranged on the eluent inlet pipe 12;

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

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

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

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

[0054] The protection column 17 and the gel permeation chromatography size exclusion column 18 are arranged in a column oven 19;

[0055] The computer 22 is connected to the ultraviolet detector 21 .

[0056] The sampling pump 9, the eluent delivery pump 15 and the pipeline are made of polyetheretherketone (PEEK) material to avoid metal contamination and can resist high pressure, acid and alkali, and organic phase corrosion.

[0057] Main component functions:

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

[0059] b) Multi-position selector valve 5: By switching the connection between the multi-position selector valve 5 and the stop valve 4 or the injector 8, the injection switching of the water sample and the standard solution can be realized.

[0060] c) Multichannel injection valve: The connection between the quantitative loop 16 and the sampling pump 9 or the eluent delivery pump 15 is switched through the multichannel injection valve 11 to realize the switching between the injection process and the analysis process. The implementation method is: when the quantitative loop 16 is connected to the sampling pump 9, it is in the sample injection process; when the quantitative loop 16 is switched to be connected to the eluent delivery pump 15, it is in the sample analysis process.

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

[0062] e) Gel Permeation Chromatography Size Exclusion Column 18: When the sample enters the gel permeation chromatography size exclusion column, molecules with a volume larger than the gel pore size flow through the gaps between the gel particles, and molecules with a volume smaller than the gel pore size enter the gel pores and diffuse in the gaps between the gel pores and the particles; therefore, large volume molecules have a shorter retention time in the chromatographic column and are eluted preferentially, while small volume molecules have a longer retention time, thereby achieving separation of molecules of different volumes.

[0063] f) Ultraviolet detector 21: PAA solution has a maximum absorption value in the ultraviolet region, and has an obvious and stable detection signal on the ultraviolet detector 21. It is less interfered by other substances in the background solution, so the ultraviolet detector 21 is selected for detection.

[0064] When in the injection mode, the liquid sample enters the multi-way injection valve 11 through the outlet of the sampling pump 9 , flows through the quantitative ring 16 , and the excess liquid sample flows out through the waste liquid discharge pipe 10 .

[0065] When in detection mode, the multi-channel injection valve 11 rotates to connect the eluent delivery pump 15 with the quantitative loop 16. The eluent delivery pump 15 delivers 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 size exclusion column 18, is separated by the chromatographic column, and then flows into the waste liquid pipe at the other end of the self-regeneration ion suppressor 20 and the ultraviolet detector 21 for discharge.

[0066] The embodiment of the present invention also discloses an online detection method for the content of polyacrylic acid dispersant using the device described in the above technical solution, comprising the following steps:

[0067] Step 1: Draw the standard curve, including:

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

[0069] The standard solutions have concentrations of 10 μg / L, 50 μg / L, 200 μg / L, 500 μg / L, and 1000 μg / L, respectively, and are stored at 4° C. in a temperature-controlled box 6;

[0070] Step 1-2: standard solution injection;

[0071] Specifically, the sample injector 8 delivers the standard solution to the multi-channel injection valve 11 through the multi-position selector valve 5 and the sampling pump 9, and the standard solution injection flow rate is 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 delivers the eluent into the multi-channel injection valve 11, 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, and balances the fluid system in the device;

[0073] The flow rate of the eluent 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] Step 1-3: elution analysis;

[0075] Specifically:

[0076] The multichannel injection valve 11 is switched to connect the eluent delivery pump 15 with the quantitative loop 16. The eluent delivery pump 15 delivers the eluent into the multichannel injection valve 11, so that the liquid stored in the quantitative loop 16 flows through the guard column 17 and the gel permeation chromatography size 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 flow rate of the eluent 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] Step 1-4: Draw a standard curve;

[0079] Under the stable and optimal working state of the device, a series of standard solutions are tested, and the peak position of each chromatogram and the peak integral area value of the detection signal are recorded; a standard curve is drawn with the concentration as the horizontal axis and the peak integral area value as the vertical axis.

[0080] Step 2: Sample online testing, including:

[0081] Step 2-1: sample injection;

[0082] Specifically: the water sample flows through the water sampling pipeline 1 and the first control valve 2, and flows through the filter 3 to remove particulate matter; the filtered water sample flows through the stop valve 4 and the multi-position selection valve 5, and is transported by the sampling pump 9, and the water sample flow rate is 1 to 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 into the multi-channel injection valve 11, 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, and balances the system.

[0083] The flow rate of the eluent 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 multichannel injection valve 11 is switched to connect the eluent delivery pump 15 with the quantitative loop 16, and the eluent delivery pump 15 delivers the eluent into the multichannel injection valve 11, so that the liquid stored in the quantitative loop 16 flows through the guard column 17 and the gel permeation chromatography size 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. The flow rate of the eluent 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.

[0086] Step 2-3: Test result analysis;

[0087] The water samples were tested online at regular intervals, the peak positions on the chromatogram were compared and the integrated area values ​​of the signal peaks were recorded, and the content of polyacrylic acid in the unknown water samples was calculated from the standard curve.

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

[0089] The polyacrylic acid standard solution was used as the analysis sample, and the background solution was used as the solvent to prepare spiked samples with theoretical polyacrylic acid contents of 33 ppb, 100 ppb, and 100 ppb, respectively. The device was used for online chromatographic detection, and the spiked recovery rate was calculated;

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

[0091] In order to further understand the present invention, the online detection method and device for the polyacrylic acid dispersant content provided by the present invention are described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0092] Example 1

[0093] The water 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 stop valve 4. The multiple inlets of the multi-position selector valve 5 are respectively connected to the standard solution storage bottles 7. The outlet of the multi-position selector valve 5 is connected to the sampling pump 9.

[0094] When in the injection mode, the liquid sample enters the multi-way injection valve 11 through the outlet of the sampling pump 9, flows through the quantitative loop 16, and then flows out from the waste liquid discharge pipe 10. When in the detection mode, the multi-way injection valve 11 rotates. In this mode, the liquid sample enters the multi-way injection valve 11 from the outlet of the sampling pump 9 and directly flows out from the waste liquid discharge pipe 10; while the ultrapure water eluent flows through the degassing device 14 and the eluent delivery pump 15 into the multi-way injection valve 11, flows through the quantitative loop 16, and then flows into the guard column 17 from the outlet of the multi-way injection valve 11, and then flows 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, and 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) Drawing of standard curve

[0097] a) Standard solution preparation process:

[0098] Use high-purity water to prepare a mixed solution of 5 mg / L ethanolamine and 100 μg / L hydrazine 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 above background solution, shake well, and you can get a 1 g / L polyacrylic acid stock solution, which is stored at 4 ° C for later use. Accurately take a certain amount of polyacrylic acid stock solution and dilute it with high-purity water to 10, 50, 200, 500, 1000 μg / L standard solutions, place them in the standard solution storage bottle 7, and set the temperature of the temperature control box 6 to 4 ° C for storage.

[0099] b) Standard solution injection process:

[0100] The injector 8 delivers the standard solution to the multi-channel injection valve 11 through the multi-position selector valve 5 and the sampling pump 9. The standard solution injection flow rate is in the range of 1 to 50 mL / min. The standard solution is stored in the quantitative loop 16 and then discharged from the waste liquid discharge pipe 10. The eluent delivery pump 15 delivers the eluent to the multi-channel injection valve 11, 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 balance the system. The flow rate of the eluent 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.

[0101] c) Elution analysis process:

[0102] The six-channel injection valve (11) is switched to connect the eluent delivery pump (15) with the quantitative loop (16), and the eluent delivery pump (15) delivers the eluent into the six-channel injection valve (11), so that the liquid stored in the quantitative loop flows through the guard column (17) and the gel permeation chromatography size exclusion column (18), is separated by the chromatographic column (18), and then flows into the self-regenerating ion suppressor (20) and the ultraviolet detector (21) for detection and analysis. The flow rate of the eluent 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.

[0103] d) Standard curve drawing process:

[0104] Turn on the power, debug the instrument to the best working state, and preheat for more than 1 hour to stabilize the instrument baseline. Under the best working state of the instrument, test a series of standard solutions, record the peak position of each chromatogram and the peak integral area value of the detection signal; draw a standard curve with concentration as the horizontal axis and peak integral area value as the vertical axis.

[0105] (2) Sample online testing process

[0106] a) Sample injection process:

[0107] The water sample flows through the water sampling tube 1, the first control valve 2, and the filter 3 to remove particles; the filtered water sample flows through the stop valve 4, the multi-position selector valve 5, and is transported by the sampling pump 9. The sample flow rate is in the range of 1 to 50 mL / min. The water sample is stored in the quantitative loop 16 and then discharged from the waste liquid discharge pipe 10; the eluent delivery pump 15 sends the eluent into the six-channel injection valve 11, 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 balance the system. The flow rate of the eluent 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.

[0108] b) Elution analysis process:

[0109] The multi-channel injection valve 11 is switched to connect the eluent delivery pump 15 with the quantitative loop 16. The eluent delivery pump 15 delivers the eluent into the multi-channel injection valve 11, so that the liquid stored in the quantitative loop flows through the guard column 17 and the gel permeation chromatography size exclusion column 18, is separated by the chromatographic column 18, and then flows into the self-regenerating ion suppressor 20 and the ultraviolet detector 21 for detection and analysis. The flow rate of the eluent 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.

[0110] c) Test result analysis

[0111] The water samples were tested online at regular intervals, the peak positions on the chromatogram were compared and the integrated area values ​​of the signal peaks were recorded, and the content of polyacrylic acid in the unknown water samples was calculated from the standard curve. Figure 2 To illustrate the effect of using this method to test PAA, the measurement results are shown in Table 1 below.

[0112] Table 1 Example of measurement results

[0113]

[0114] (3) Spiked recovery and repeatability test

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

[0116] Table 2 Results of spike 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 analysis sample, and high-purity water was used as the solvent to prepare a spiked sample with a PAA theoretical content of 50 ppb. The results of repeated testing 7 times are shown in Table 3, and the average recovery rate was 99.3%.

[0119] Table 3 Repeated test and spike recovery test results

[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 embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0122] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to 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 sampling pipeline and the standard solution storage bottle are respectively connected to different inlets of the multi-position selection valve; A first control valve, a filter and a stop valve are sequentially arranged on the water sampling pipeline; The outlet of the multi-position selector valve and the eluent inlet pipe are connected to the multi-channel injection valve; A second control valve and a degassing device are sequentially arranged on the eluent inlet pipe; A sample injector 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 injection valve; A quantitative loop is arranged in the multi-channel injection valve, one of the channels of which is connected to a waste liquid discharge pipe; The outlet of the multi-channel injection valve is sequentially connected to a guard column, a gel permeation chromatography size exclusion column, a self-regenerating ion suppressor, and an ultraviolet detector; The computer is connected to the UV detector.

2. The online detection device for polyacrylic acid dispersant content according to claim 1, characterized in that: The standard solution storage bottle is arranged in a temperature control box.

3. The online detection device for polyacrylic acid dispersant content according to claim 1, characterized in that: The protective column and the gel permeation chromatography size exclusion column are arranged in a column oven.

4. The online detection device for polyacrylic acid dispersant content according to claim 1, characterized in that: A washing liquid delivery pump is arranged between the degassing device and the multi-channel injection valve.

5. An online detection method for polyacrylic acid dispersant content using the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Prepare a standard solution, use the standard solution to fill the fluid, and balance the fluid system in the entire device; The multi-channel injection valve is switched to connect the eluent delivery pump with the quantitative loop. The eluent delivery pump delivers 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 size 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; Draw a standard curve; Step 2: After the water sample is filtered, it is injected to balance the fluid system in the entire device; The multi-channel injection valve is switched to connect the eluent delivery pump with the quantitative loop. The eluent delivery pump delivers 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 size 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; the flow rate of the eluent 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.

6. The method for online detection of polyacrylic acid dispersant content according to claim 5, characterized in that: In step 1, the method of using the standard liquid to balance the fluid system in the entire device is: The injector delivers the standard solution into the multi-channel injection valve through the multi-position selector valve and the sampling pump. The standard solution is stored in the quantitative loop and then discharged from the waste liquid drain pipe. The eluent delivery pump delivers the eluent into the multi-channel injection valve, flows through the guard column, the gel permeation chromatography size exclusion column, the self-regenerating ion suppressor, and the ultraviolet detector to balance the fluid system in the device. The injection flow rate of the standard solution is in the range of 1 to 50 mL / min; The flow rate of the eluent 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.

7. The method for online detection of polyacrylic acid dispersant content according to claim 5, characterized in that: The concentrations of the standard solutions were 10 μg / L, 50 μg / L, 200 μg / L, 500 μg / L, and 1000 μg / L, respectively, and were stored at 4° C. in a temperature-controlled box.

8. The method for online detection of polyacrylic acid dispersant content according to claim 5, characterized in that: In step 2, the specific method of injecting the water sample after filtering is: The water sample flows through the water sampling pipeline and the first control valve, and flows through the filter to remove particulate matter; the filtered water sample flows through the stop valve and the multi-position selection valve, and is transported 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, flows through the guard column, gel permeation chromatography size exclusion column, self-regenerating ion suppressor, and ultraviolet detector to balance the system.

9. The method for online detection of polyacrylic acid dispersant content according to claim 8, characterized in that: In step 2, the water sample flow rate is 1 to 50 mL / min.

10. The method for online detection of polyacrylic acid dispersant content according to claim 5, characterized in that: It also includes step 3: spike recovery and repeatability test; Specifically include: The polyacrylic acid standard solution was used as the analysis sample, and the background solution was used as the solvent to prepare spiked samples with theoretical polyacrylic acid contents of 33 ppb, 100 ppb, and 100 ppb, respectively. The device was used for online chromatographic detection, and the spiked recovery rate was calculated; A polyacrylic acid standard solution with a peak molecular weight of Mp 62900 was used as the analytical sample, and high-purity water was used as the solvent to prepare a spiked sample with a PAA theoretical content of 50 ppb, with a repeatability test rate.

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