Synchronous detection system and method for ammonia and hydrazine

Abstract

The invention relates to the field of water quality monitoring of a secondary loop of a nuclear power plant, in particular to a synchronous detection system and method for ammonia and hydrazine. The method comprises the following steps: removing impurities in a sample by utilizing filtration and reverse chromatography; the sample is quantified to 240-260 [mu] L; carrying out gradient elution on the sample by using a methanesulfonic acid solution as an eluent; wherein in the first stage, the concentration of a methanesulfonic acid solution is controlled to be 13-18 mmol / L, and a sample is washed; in the second stage, the concentration of the methanesulfonic acid solution is controlled to be 55-70 mmol / L, and the sample is Drawing a low-concentration curve based on the 10-500 [mu] g / L standard solution, and drawing a high-concentration curve based on the 500-3000 [mu] g / L standard solution; and measuring the ionic conductivity values of NH4 < + > and N2H5 < + >, automatically selecting a corresponding concentration curve according to the peak area of the ionic conductivity values, and calculating the concentration of ammonia and hydrazine. According to the invention, the synchronous detection of ammonia and hydrazine concentration is realized, the analysis process is simplified, the use of toxic and harmful substance phenol and the generation of toxic and harmful waste liquid of yellow azo compound are solved, the measurement accuracy is improved, and the relative measurement error can be controlled within + / -2.0%.

Description

Technical Field

[0001] The present invention relates to the field of secondary circuit water quality monitoring in nuclear power plants, and in particular to a synchronous detection system and method for ammonia and hydrazine. Background Art

[0002] In the secondary circuit systems of nuclear power plants, ammonia (NH3) and hydrazine (N2H4) are commonly used alkalizing agents, playing a crucial role in regulating system pH and reducing equipment corrosion. Ammonia is a colorless gas with a strong pungent odor. It dissolves readily in water to form a weakly alkaline ammonia solution, which is used to regulate the pH of the secondary circuit system and reduce the rate of corrosion in the system equipment. Hydrazine, on the other hand, is a colorless, weakly alkaline liquid with strong reducing properties. It reacts with dissolved oxygen in water, removing it and reducing the rate of corrosion in the system equipment.

[0003] Currently, nuclear power plant secondary circuit systems measure ammonia and hydrazine concentrations in feed water using spectrophotometry with phenol (GB / T 12146) and dimethylaminobenzaldehyde spectrophotometry (GB / T 6906), respectively. Due to differences in the measurement principles, simultaneous measurement of ammonia and hydrazine concentrations is impossible. Phenol, the reactant, is highly corrosive and toxic, and the indigo blue compound it produces with ammonia has a pungent odor. Furthermore, dimethylaminobenzaldehyde reacts with hydrazine under acidic conditions to produce a toxic and hazardous yellow azo compound, which pollutes the environment. Both methods have a measurement error of approximately 10%, resulting in significant errors. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a system and method for synchronous detection of ammonia and hydrazine, thereby realizing synchronous detection of ammonia and hydrazine concentrations, simplifying the analysis process, and simultaneously solving the problem of using phenol, a toxic and harmful substance, and generating toxic and harmful waste liquid of yellow azo compounds, thereby improving the accuracy of measurement and being able to control the relative error of measurement within ±2.0%.

[0005] The present invention provides a method for synchronous detection of ammonia and hydrazine, comprising the following steps:

[0006] Step 1: Remove impurities from the sample using filtration and reverse-phase chromatography;

[0007] Step 2: Quantify the sample to 240-260 μL;

[0008] Step 3: Using methanesulfonic acid solution as the eluent, the sample is gradient eluted; wherein the concentration of the methanesulfonic acid solution is controlled to be 13-18 mmol / L for elution of the sample in the first stage; and the concentration of the methanesulfonic acid solution is controlled to be 55-70 mmol / L for elution of the sample in the second stage;

[0009] Step 4: Draw a low concentration curve based on the 10 μg / L to 500 μg / L standard solution, and draw a high concentration curve based on the 500 μg / L to 3000 μg / L standard solution;

[0010] Step 5: Measuring NH4 + and N2H5 + The ion conductivity value is automatically selected according to the peak area of ​​the ion conductivity value to calculate the concentration of ammonia and hydrazine.

[0011] In a specific embodiment of the present invention, in step 1, iron oxides and corrosion products with a diameter of more than 2 μm in the sample are removed by filtration, and then organic compounds are removed by reverse chromatography.

[0012] In a specific embodiment of the present invention, in step 2, the sample is quantified to 250 μL.

[0013] In one embodiment of the present invention, in step 3, the first stage elution time is 15 to 20 minutes; the second stage elution time is 18 to 23 minutes;

[0014] After elution is completed, the concentration of the methanesulfonic acid solution is restored to 13-18 mmol / L.

[0015] In a specific embodiment of the present invention, in step 3, the injection speed of the sample and the eluent is 0.2 to 0.6 mL / min.

[0016] In a specific embodiment of the present invention, the injection speed of the sample and eluent is 0.4 mL / min.

[0017] In a specific embodiment of the present invention, in step 3, the concentration of the methanesulfonic acid solution is controlled to be 15 mmol / L in the first stage; and the concentration of the methanesulfonic acid solution is controlled to be 60 mmol / L in the second stage.

[0018] The present invention provides a synchronous detection system for ammonia and hydrazine, comprising:

[0019] The six-way valve, guard column, analytical column, suppressor, conductivity cell, data acquisition and control computer are connected in sequence;

[0020] The six-way valve is also connected to the MSA eluent generator, the reverse chromatographic column, and the waste liquid pool respectively;

[0021] The liquid inlet end of the reverse chromatographic column is connected to a filter, the filter is connected to a sample bottle, and an injection pump is arranged between the filter and the sample bottle;

[0022] The other end of the MSA eluent generator is connected to a high-purity water bottle, and an eluent pump is set between the two.

[0023] In a specific embodiment of the present invention, the analytical column is CS16 type with a specification of 3*250mm.

[0024] In a specific embodiment of the present invention, a quantitative loop is provided in the six-way valve, and the quantitative volume of the quantitative loop is 250 μL.

[0025] Compared with the prior art, the system and method for synchronous detection of ammonia and hydrazine of the present invention have the following beneficial effects:

[0026] (1) The concentrations of ammonia and hydrazine are measured simultaneously, which solves the drawback of the traditional spectrophotometric method that requires separate measurements, simplifies the operation process, reduces the workload of technicians, saves labor costs, and reduces costs and increases efficiency;

[0027] (2) The adsorption and separation of ammonia and hydrazine are completed by the analytical column, without adding any chemical reagents for reaction, and the concentration measurement of ammonia and hydrazine is completed directly, without any toxic or harmful waste liquid, which is safe, environmentally friendly and pollution-free;

[0028] (3) The lowest concentration of sample detection is trace level. Compared with the spectrophotometric method for measuring ammonia and hydrazine concentrations, the measurement range is wider and the accuracy is better. The peak curve can be automatically switched according to the high and low concentrations of ammonia and hydrazine measured;

[0029] (4) The method is advanced, easy to operate, and has a fast analysis speed, and can be promoted for use in various power plants and chemical fields.

[0030] The test results show that the present invention has higher detection accuracy and better stability, and the relative error of measurement is controlled within ±2%, with RSD ≤ 1.7%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram showing the structure of a simultaneous detection system for ammonia and hydrazine;

[0032] In the figure: 1-sample bottle; 2-injection pump; 3-filter; 4-reverse chromatography column; 5-high-purity water bottle; 6-eluent pump; 7-MSA eluent generator; 8-six-way valve; 9-waste bottle; 10-quantitative loop; 11-guard column; 12-analytical column; 13-suppressor; 14-conductivity cell; 15-data acquisition and control computer. DETAILED DESCRIPTION

[0033] In order 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, rather than for limiting the present invention.

[0034] During the operation of the unit, the concentrations of ammonia and hydrazine in the secondary circuit feed water are relatively high, with the normal ammonia concentration being around 1800μg / L and the normal hydrazine concentration being between 100 and 160μg / L; during the overhaul period, the concentrations of ammonia and hydrazine range from 0 to 3000μg / L.

[0035] An embodiment of the present invention discloses a method for simultaneous detection of ammonia and hydrazine, comprising the following steps:

[0036] Step 1: Remove impurities from the sample using filtration and reverse-phase chromatography;

[0037] Iron oxides and corrosion products with a diameter of more than 2 μm in the sample are removed by filtration, and then organic compounds are removed by reverse chromatography to prevent iron oxides, organic compounds and corrosion products from clogging and contaminating the analytical column and affecting the measurement data.

[0038] Step 2: Quantify the sample to 240-260 μL, preferably 250 μL;

[0039] Step 3: Use methanesulfonic acid solution as eluent to perform gradient elution on the sample;

[0040] Specifically, high-purity water and methanesulfonic acid (MSA) are used to adjust the concentration of the methanesulfonic acid solution. In order to facilitate the adjustment of the concentration of the methanesulfonic acid solution, the MSA eluent generator adjusts the concentration of the methanesulfonic acid by adjusting the current;

[0041] In the first stage, the concentration of the methanesulfonic acid solution is controlled to be 13-18 mmol / L, preferably 15 mmol / L; the eluent pump 6 delivers the eluent to the detection unit at an injection speed of 0.2-0.6 mL / min, and elutes the sample with a methanesulfonic acid solution of 13-18 mmol / L, preferably 15 mmol / L, to complete the NH4 + Ion separation, elution time is 18 to 23 minutes;

[0042] In the second stage, the concentration of the methanesulfonic acid solution is controlled to be 55-70 mmol / L, preferably 60 mmol / L;

[0043] The eluent pump 6 delivers the eluent to the detection unit at an injection rate of 0.2 to 0.6 mL / min, and elutes the sample with a 55 to 70 mmol / L methanesulfonic acid solution, preferably a 60 mmol / L methanesulfonic acid solution, which is beneficial to the N2H5 + Ion separation; elution time is 18 to 23 minutes;

[0044] After the elution is completed, the concentration of the methanesulfonic acid solution is restored to 13-18 mmol / L, preferably 15 mmol / L; the injection speed of the sample and the eluent is preferably 0.4 mL / min.

[0045] Step 4: Draw a low concentration curve based on the 10μg / L to 500μg / L standard solution, and draw a high concentration curve based on the 500μg / L to 3000μg / L standard solution. The two curves use 500μg / L as the shared point. The low concentration standard curve is drawn through the low concentration standard solution points of 10μg / L, 20μg / L, 50μg / L, 100μg / L, 200μg / L, and 500μg / L. The high concentration standard curve is drawn through the high concentration standard solution points of 500μg / L, 1000μg / L, 2000μg / L, and 3000μg / L.

[0046] Step 5: Measuring NH4 + and N2H5 + The ion conductivity value is automatically selected according to the peak area of ​​the ion conductivity value to calculate the concentration of ammonia and hydrazine.

[0047] The embodiment of the present invention discloses a synchronous detection system for ammonia and hydrazine, comprising: a sample bottle 1, a sample injection pump 2, a filter 3, a reverse chromatographic column 4, a high-purity water bottle 5, an eluent pump 6, an MSA eluent generator 7, a six-way valve 8, a waste liquid bottle 9, a quantitative loop 10, a guard column 11, an analytical column 12, a suppressor 13, a conductivity cell 14, and a data acquisition and control computer 15;

[0048] The six-way valve 8, the guard column 11, the analytical column 12, the suppressor 13, the conductivity cell 14, and the data acquisition and control computer 15 are connected in sequence;

[0049] The six-way valve 8 is also connected to the MSA eluent generator 7, the reverse chromatography column 4, and the waste liquid pool 14 respectively;

[0050] The liquid inlet end of the reverse chromatographic column 4 is connected to the filter 3, the filter 3 is connected to the sample bottle 1, and an injection pump 2 is provided between the filter 3 and the sample bottle 1;

[0051] The other end of the MSA eluent generator 7 is connected to the high-purity water bottle 5, and an eluent pump 6 is provided between the two.

[0052] A quantitative ring 10 is provided in the six-way valve 8 , and the quantitative volume of the quantitative ring 10 is 250 μL.

[0053] The pore size of the filter 3 is no greater than 2 μm.

[0054] The analytical column 12 is of CS16 type with a size of 3*250 mm, which can well separate ammonia from hydrazine.

[0055] In order to further understand the present invention, the synchronous detection system and method of ammonia and hydrazine provided by the present invention are described in detail below with reference to the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0056] Example 1

[0057] Collect the secondary circuit feed water and place it in the sample bottle 1. Start the analysis, and the sampling pump 2 automatically extracts the sample water from the sample bottle 1. The sample water is first filtered through a filter 3 with a pore size of 2μm to remove iron oxides and corrosion products with a diameter of more than 2μm in the sample water, and then passes through a reverse chromatographic column 4 to remove organic compounds.

[0058] The sampling pump 2 loads the filtered sample water into the 250μL quantitative loop 10 through the six-way valve 8. The loading time is 2 minutes to ensure that the 250μL quantitative loop 10 is completely rinsed and filled with sample water. During the loading process, excess sample water is discharged into the waste liquid bottle 9.

[0059] The eluent pump 6 delivers the high-purity water in the high-purity water bottle 5 to the MSA eluent generator 7. The MSA eluent generator 7 adjusts the concentration of the MSA eluent by adjusting the current. In the first stage, the eluent pump 6 delivers the sample and eluent to the detection unit at 0.4 mL / min, passing through the guard column 11, the analytical column 12, the suppressor 13, and the conductivity cell 14. The eluent is a 15 mmol / L methanesulfonic acid solution. The elution time is 18 minutes. After elution, NH4 + Ionic conductivity value measurement,

[0060] In the second stage, the eluent pump 6 delivers the sample and eluent to the detection unit at 0.4 mL / min, passes through the guard column 11, the analytical column 12, the suppressor 13, and the conductivity cell 14. The eluent is a 60 mmol / L methanesulfonic acid solution, and the elution time is 22 minutes. After elution, the N2H5 + Ionic conductivity value measurement;

[0061] Based on the Python programming language, a curve fitting algorithm is used to complete the drawing of two display screens with automatic switching between high and low concentrations of the ammonia and hydrazine measurement ranges on the ion chromatography chameleon software of the data acquisition and control computer 15, wherein the low concentration curve is drawn based on a standard solution of 10 μg / L to 500 μg / L, and the high concentration curve is drawn based on a standard solution of 500 μg / L to 3000 μg / L. The two curves use 500 μg / L as a shared point, and the low concentration standard curve is drawn by using the low concentration standard solution points of 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, 200 μg / L, and 500 μg / L. The high concentration standard curve is then drawn by using the high concentration standard solution points of 500 μg / L, 1000 μg / L, 2000 μg / L, and 3000 μg / L.

[0062] According to the peak area of ​​the ion conductivity value, the corresponding concentration curve is automatically selected to calculate the concentration of ammonia and hydrazine. This system is used to test the ammonia standard verification sample:

[0063] The concentration value of the ammonia standard verification sample was 1500 μg / L and was measured at 1512.36 μg / L, with a relative error of +0.82%;

[0064] The concentration value of the ammonia standard verification sample was 2300 μg / L and was measured at 2325.94 μg / L, with a relative error of +1.13%;

[0065] Testing of hydrazine standard verification samples:

[0066] The concentration value of the 100 μg / L sample was measured to be 99.16 μg / L, with a relative error of -0.84%;

[0067] The concentration value of the 400 μg / L sample was measured to be 406.03 μg / L, with a relative error of +1.51%;

[0068] All relative errors are less than ±1.51%, which meets the technical requirement of controlling the measurement error within ±2.0%.

[0069] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0070] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simultaneous detection of ammonia and hydrazine, characterized in that: The following steps are involved: Step 1: Remove impurities from the sample using filtration and reverse-phase chromatography; Step 2: Quantify the sample to 240-260 μL; Step 3: Use methanesulfonic acid solution as eluent to perform gradient elution on the sample; In the first stage, the concentration of methanesulfonic acid solution was controlled at 13-18 mmol / L to elute the sample; In the second stage, the concentration of methanesulfonic acid solution was controlled to be 55-70 mmol / L to elute the sample; Step 4: Draw a low concentration curve based on the 10 μg / L to 500 μg / L standard solution, and draw a high concentration curve based on the 500 μg / L to 3000 μg / L standard solution; Step 5: Measuring NH4 + and N2H5 + The ion conductivity value is automatically selected according to the peak area of ​​the ion conductivity value to calculate the concentration of ammonia and hydrazine.

2. The method for simultaneous detection of ammonia and hydrazine according to claim 1, wherein: In the step 1, iron oxides and corrosion products with a diameter of more than 2 μm in the sample are removed by filtration, and then organic compounds are removed by reverse chromatography.

3. The method for simultaneous detection of ammonia and hydrazine according to claim 1, wherein: In step 2, the sample is quantified to 250 μL.

4. The method for simultaneous detection of ammonia and hydrazine according to claim 1, wherein: In step 3, the first stage elution time is 15 to 20 minutes; the second stage elution time is 18 to 23 minutes; After elution is completed, the concentration of the methanesulfonic acid solution is restored to 13-18 mmol / L.

5. The method for simultaneous detection of ammonia and hydrazine according to claim 1, wherein: In step 3, the injection speed of the sample and the eluent is 0.2 to 0.6 mL / min.

6. The method for simultaneous detection of ammonia and hydrazine according to claim 5, characterized in that: The injection speed of the sample and eluent was 0.4 mL / min.

7. The method for simultaneous detection of ammonia and hydrazine according to claim 1, wherein: In step 3, the concentration of the methanesulfonic acid solution is controlled to be 15 mmol / L in the first stage; and the concentration of the methanesulfonic acid solution is controlled to be 60 mmol / L in the second stage.

8. A synchronous detection system for ammonia and hydrazine, characterized in that: include: The six-way valve, guard column, analytical column, suppressor, conductivity cell, data acquisition and control computer are connected in sequence; The six-way valve is also connected to the MSA eluent generator, the reverse chromatographic column, and the waste liquid pool respectively; The liquid inlet end of the reverse chromatographic column is connected to a filter, the filter is connected to a sample bottle, and an injection pump is arranged between the filter and the sample bottle; The other end of the MSA eluent generator is connected to a high-purity water bottle, and an eluent pump is set between the two.

9. The synchronous detection system of ammonia and hydrazine according to claim 8, characterized in that: The analytical column is CS16 type with a specification of 3*250mm.

10. The synchronous detection system of ammonia and hydrazine according to claim 8, characterized in that: A quantitative loop is provided in the six-way valve, and the quantitative volume of the quantitative loop is 250 μL.

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