Method for testing total silicon content of a power plant water vapor system
By combining atomic absorption spectrometry with specific solution treatment and matrix modifiers, the problems of cumbersome operation, slow speed and environmental pollution in the determination of total silicon content in the water-steam system of power plants have been solved, and rapid and accurate determination of silicon dioxide concentration has been achieved.
Patent Information
- Application Number
- CN202210669493.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-14
- Publication Date
- 2026-02-17
- Estimated Expiration
- 2042-06-14
AI Technical Summary
Existing methods for determining the total silicon content in power plant water-steam systems are cumbersome, slow, pollute the environment, and have low accuracy.
By employing atomic absorption spectrometry combined with specific solution treatment and matrix modifiers, and through standard curve plotting and analysis, the concentration of silica in a water vapor system can be rapidly and accurately determined.
It improves the sensitivity of silica determination, is easy to operate, highly accurate, environmentally friendly, and fast in testing.
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Figure CN114858732B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of testing scale in the inner wall of a furnace tube, and particularly relates to a method for testing total silicon content in a water-steam system of a power plant. BACKGROUND
[0002] Silicon and its compounds in the water-steam system are easy to form scale in the inner wall of a furnace tube and salt deposits on turbine blades, which has a great impact on the safety and economy of the operation of a steam turbine. With the increase of installed capacity of high-parameter units, the quality of the water-steam system is required to be higher and higher. According to the provisions in GB / T12145-2016, the content of silicon dioxide in the water-steam system is regulated, and therefore, accurate and rapid determination of the total silicon in the water-steam system is a guarantee for the safe operation of the unit. At present, the spectrophotometric method in DL / T502.3-2006 is generally used in the laboratory of a power plant to determine the total silicon, and the reagents used in the method have a stimulating odor, some reagents need to be prepared on site, the testing speed is slow, the types of reagents are many, the operation is complicated, and the environment is polluted.
[0003] Based on the many defects of the test of silicon dioxide in the laboratory of a power plant and the wide use of atomic absorption spectrometers in power plants, the determination of the total silicon in the water-steam system by atomic absorption spectrometers can make up for the disadvantages of the existing test methods. SUMMARY
[0004] The present application aims to provide a method for testing the total silicon in the water-steam system of a power plant, which has small errors, high precision and fast testing speed.
[0005] To achieve the above-mentioned purpose, the method for testing the total silicon in the water-steam system of a power plant comprises the following steps:
[0006] A method for testing the total silicon content in the water-steam system of a power plant comprises the following steps:
[0007] A water sample of the water-steam system of a power plant is taken, hydrochloric acid solution and hydrofluoric acid solution are added, and after sealing, it is placed in a boiling water bath for heating. After heating, it is cooled to room temperature, boric acid solution is added, and the sample is shaken to obtain a sample;
[0008] Different concentrations of standard solutions of silicon dioxide are taken, and hydrochloric acid solution and hydrofluoric acid solution are added respectively. After sealing, they are placed in a boiling water bath for heating. After heating, they are cooled to room temperature, boric acid solution is added, and the standard working solutions of different concentrations are shaken to obtain them;
[0009] When drawing a standard curve and determining a sample by atomic absorption, Ca 2+ matrix modifier is added first, and then the standard working solution or the sample is added;
[0010] Each standard working solution is analyzed by atomic absorption, and the absorbance corresponding to each standard working solution is recorded. Then, the absorbance is taken as the vertical standard, and the concentration is taken as the horizontal coordinate, and a standard working curve is drawn.
[0011] The water sample of the water vapor system to be measured is analyzed and determined by atomic absorption, and the concentration of silicon dioxide in the water sample to be measured is determined according to the absorbance of silicon dioxide in the water sample to be measured.
[0012] As a further improvement of the present application, the nitric acid solution is prepared from the silicon-free reagent water and pure nitric acid, and the volume ratio of the silicon-free reagent water to the pure nitric acid is 1:1.
[0013] The hydrofluoric acid solution is prepared from the pure hydrofluoric acid and the silicon-free reagent water, and the volume ratio of the pure hydrofluoric acid to the silicon-free reagent water is 1:84.
[0014] The boric acid solution is prepared from the pure boric acid and the silicon-free reagent, and the concentration is 40 mg / L.
[0015] As a further improvement of the present application, Ca 2+ The preparation method of the matrix modifier is as follows:
[0016] The calcium carbonate is weighed, wetted with water, and dropped with nitric acid until dissolved, and then excess nitric acid is added and diluted with water to Ca 2+ The concentration is 1000 mg / L, and the Ca 2+ standard stock solution is obtained.
[0017] The Ca 2+ standard stock solution is diluted with the silicon-free reagent water, and the Ca 2+ concentration is 60 mg / L, and the matrix modifier Ca 2 + solution is prepared.
[0018] As a further improvement of the present application, the conductivity of the silicon-free reagent water is 18.3 MΩ·cm.
[0019] As a further improvement of the present application, the concentration of the silicon dioxide standard solution is 0 μg / L-100 μg / L, the silicon dioxide standard solution is prepared as a silicon dioxide gradient solution, and the silicon dioxide gradient solution is added to the sample in the same amount and order.
[0020] As a further improvement of the present application, Ca 2+ The volume ratio of the matrix modifier to the standard working solution or the sample is 1:2.
[0021] As a further improvement of the present application, the heating time in the boiling water bath after sealing is 15-25 minutes.
[0022] As a further improvement of the present application, the conditions for atomic absorption determination of the silicon dioxide content are as follows: the wavelength is 251.6 nm, the time constant is 0.1 second, the slit width is 0.4 nm, and the lamp current is 10 mA.
[0023] As a further improvement of the present application, the system temperature condition for measuring silicon dioxide is:
[0024]
[0025] The hollow cathode silicon lamp is used for measuring silicon dioxide, the graphite tube uses a C type pyrolytic graphite tube with a coating, and the gas is high-purity argon.
[0026] As a further improvement of the present application, all the vessels in the method are made of polypropylene material.
[0027] The present application has the following beneficial effects:
[0028] The present application first proposes a test method for measuring total silicon in a water vapor system of a power plant by using an atomic absorption spectrometer. By adding a matrix modifier, the sensitivity of the measurement of silicon dioxide can be improved by 404.3%. The water sample to be measured is analyzed and measured by using the atomic absorption spectrometer, and the concentration of silicon dioxide in the water sample to be measured is determined according to the standard working curve according to the absorbance of silicon dioxide in the water sample to be measured. When measuring total silicon (calculated as SiO2), the linear regression determination coefficient R 2 can reach 0.999 or more. Therefore, the method of the present application is convenient to operate, high in accuracy, fast in testing, and friendly to the environment. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 It is a flow chart of a test method for total silicon in a water vapor system of a power plant.
[0030] Figure 2 It is a standard working curve diagram of a test method for total silicon in a water vapor system of a power plant. DETAILED DESCRIPTION
[0031] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.
[0032] It should be noted that when an element is referred to as being “disposed on” another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being “connected” to another element, it can be directly connected to the other element or there can be an intervening element. The terms “vertical”, “horizontal”, “left”, “right”, and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiments.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0034] like Figure 1 As shown, the present invention provides a method for testing the total silicon content of a power plant's water-steam system, comprising the following steps:
[0035] Take a water sample from the power plant's steam system, add hydrochloric acid solution and hydrofluoric acid solution, seal it, and heat it in a boiling water bath. After heating, cool it to room temperature, add boric acid solution, and shake well to obtain the sample.
[0036] Take silica standard solutions of different concentrations, add hydrochloric acid solution and hydrofluoric acid solution respectively, seal and heat in boiling water bath, cool to room temperature after heating, add boric acid solution, shake well to obtain standard working solutions of different concentrations;
[0037] When plotting the standard curve and measuring the sample using atomic absorption spectrometry, Ca is added first. 2+ Add the matrix modifier to the standard working solution or sample;
[0038] Atomic absorption was used to analyze each standard working solution, and the absorbance of the standard working solution at each point was recorded. Then, a standard working curve was plotted with absorbance as the vertical axis and concentration as the horizontal axis.
[0039] Atomic absorption spectrometry was used to analyze and measure water samples from the water vapor system under test, and the concentration of silica in the water sample was determined based on the absorbance of silica in the water sample.
[0040] This method is easy to operate, highly accurate, quick to test, and environmentally friendly.
[0041] The present invention will now be described in further detail with reference to the accompanying drawings.
[0042] This invention discloses a method for testing the total silicon content in a power plant's water-steam system, comprising the following steps:
[0043] 1) Take a water sample from the water vapor system, add nitric acid and hydrofluoric acid to digest the water sample in a water bath, cool to room temperature, and add boric acid solution;
[0044] 2) Adjust the atomic absorption spectrometer;
[0045] 3) Set up the test method;
[0046] 4) Prepare a silica gradient solution. The silica gradient solution should be added in the same amount and order as the sample.
[0047] 5) Draw standard working curve, before sample injection, first advance matrix modifier, then advance silica gradient solution;
[0048] 6) Use atomic absorption spectrometer to determine the absorbance of different silica concentrations, and draw standard curve with concentration as abscissa and absorbance as ordinate;
[0049] 7) Use atomic absorption spectrometer to analyze and determine the water sample to be tested, and determine the silica concentration of the water sample to be tested according to the silica absorbance of the water sample to be tested and the standard working curve.
[0050] In order to enable the personnel in the technical field to better understand the technical scheme of the present application, the technical scheme in the implementation of the present application will be clearly and completely described below in combination with the examples of the present application.
[0051] Example 1
[0052] The testing method for total silica content of a power plant water vapor system of the present application comprises the following steps:
[0053] 1) Preparation of reagents:
[0054] Nitric acid solution: 100 mL of silicon-free reagent water is measured by a polypropylene measuring cylinder and poured into a 250 mL polypropylene bottle, and then 100 mL of high-purity nitric acid is measured by a polypropylene measuring cylinder and poured into the polypropylene bottle containing 100 mL of silicon-free reagent water, and shaken well for standby.
[0055] Hydrofluoric acid solution: 1 mL of high-purity hydrofluoric acid is taken by a polypropylene pipette and poured into a 100 mL polypropylene bottle, and then 84 mL of silicon-free reagent water is measured by a polypropylene measuring cylinder and poured into the polypropylene bottle containing 1 mL of hydrofluoric acid, and shaken well for standby.
[0056] Boric acid solution: 40 g of high-purity boric acid is weighed and dissolved in about 600 mL of silicon-free reagent water, and diluted to 1 L.
[0057] Ca 2+ Preparation of standard stock solution: 2.497 g of calcium carbonate (high-purity CaCO3, calcined at 105℃-110℃ to constant weight) is weighed into a 100 mL polypropylene beaker, wetted with water, and added dropwise with nitric acid (high-purity) until dissolved, and then 2.5 mL of nitric acid is added in excess, transferred to a 1000 mL polypropylene volumetric flask, and diluted with water to the mark. The concentration of Ca 2+ is 1000 mg / L.
[0058] Matrix modifier Ca 2+ solution: 6 mL of Ca 2+ standard stock solution is transferred to a 100 mL polypropylene volumetric flask, and diluted to 100 mL with silicon-free reagent water to obtain a Ca2+ The concentration is 60 mg / L.
[0059] 2) Sample preparation: take about 125 mL of water sample from the water vapor system of the power plant with a polypropylene bottle, shake the sample, accurately measure 100 mL of the sample with a polyethylene measuring cylinder, and put it in a 125 mL polypropylene bottle. Add 1 mL of hydrochloric acid solution and 1 mL of hydrofluoric acid solution. Seal the polypropylene bottle with a sealing cap, heat it in a boiling water bath for 20 minutes, cool it to room temperature, add 4 mL of boric acid solution, and shake well.
[0060] 3) Take 1 mL of silica mother liquor (100 mg / L) in a 100 mL polypropylene volumetric flask with a polypropylene pipette, and dilute to the mark with silicon-free reagent water to obtain a silica solution with a silica content of 1 mg / L. Take 0 mL, 1 mL, 3 mL, 5 mL, 7 mL, and 10 mL of the 1 mg / L silica solution in 100 mL polypropylene volumetric flasks, respectively, and dilute to the mark with silicon-free reagent water to obtain silica standard solutions of 0 μg / L, 10 μg / L, 30 μg / L, 50 μg / L, 70 μg / L, and 100 μg / L. Transfer them into 125 mL polypropylene bottles with sealing caps, respectively, and add 1 mL of hydrochloric acid solution and 1 mL of hydrofluoric acid solution. Seal the polypropylene bottles with sealing caps, heat them in a boiling water bath for 20 minutes, cool them to room temperature, add 4 mL of boric acid solution, and shake well.
[0061] 4) When drawing the standard curve and measuring the sample by atomic absorption, add 60 mg / L of Ca 2+ matrix modifier 10 μL, and then add 20 μL of the standard working solution or the sample.
[0062] 5) Analyze each standard working solution by atomic absorption, record the absorbance corresponding to each standard working solution, and then draw the standard working curve with absorbance as the vertical standard and concentration as the horizontal coordinate. The working curve equation is automatically calculated and stored by the instrument.
[0063] 6) Analyze and measure the water vapor system water sample to be tested by atomic absorption, and determine the concentration of silica in the water sample to be tested according to the absorbance of silica in the water sample to be tested.
[0064] 7) The setting conditions for measuring the silica content by atomic absorption instrument are as follows: wavelength 251.6 nm, time constant 0.1 second, slit width 0.4 nm, and lamp current 10 mA.
[0065] 8) The system temperature program for measuring silica is as follows:
[0066]
[0067] 9) Hollow cathode silicon lamp, graphite tube is C type pyrolytic graphite tube with coating, and the gas is high-purity argon.
[0068] 10) All the vessels in the method are made of polypropylene, and glass is not used.
[0069] 11) The water conductivity of the silicon-free reagent used in the method is 18.3 MΩ·cm.
[0070] As Figure 2 shown in the final test result curve diagram of the embodiment of the application, the concentration of silicon dioxide in the water sample to be tested in the application meets the linear requirement.
[0071] Example 2
[0072] The method for testing the total silicon content of a power plant water vapor system of the application comprises the following steps:
[0073] 1) Preparation of reagents:
[0074] The method is the same as the preparation method in Example 1, and one preparation can be reused.
[0075] 2) Sample preparation: about 125 mL of water sample of the power plant water vapor system is taken in a polypropylene bottle, the water sample is shaken, 100 mL of the water sample is accurately measured by using a polyethylene measuring cylinder, and is placed in a 125 mL polypropylene bottle, 1 mL of hydrochloric acid solution and 1 mL of hydrofluoric acid solution are added, the polypropylene bottle is sealed with a sealing cover, is placed in a boiling water bath for heating for 15 minutes, is cooled to room temperature, 4 mL of boric acid solution is added, and is shaken.
[0076] 3) 1 mL of silicon dioxide mother liquor (100 mg / L) is taken in a 100 mL polypropylene volumetric flask by using a polypropylene pipette, and is diluted to the scale with silicon-free reagent water to obtain a silicon dioxide solution with a silicon dioxide content of 1 mg / L; 0 mL, 1 mL, 2 mL, 4 mL, 6 mL and 9 mL of the silicon dioxide solution with a concentration of 1 mg / L are taken in 100 mL polypropylene volumetric flasks, respectively, and are diluted to the scale with silicon-free reagent water to obtain silicon dioxide standard solutions with concentrations of 0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 60 μg / L and 90 μg / L, respectively, and are transferred into 125 mL polypropylene bottles with sealing covers, 1 mL of hydrochloric acid solution and 1 mL of hydrofluoric acid solution are added, respectively, the polypropylene bottles are sealed with sealing covers, are placed in a boiling water bath for heating for 15 minutes, are cooled to room temperature, 4 mL of boric acid solution is added, and is shaken.
[0077] 4) When the standard curve is drawn and the sample is determined by using atomic absorption, 10 μL of Ca 2+ matrix modifier with a concentration of 60 mg / L is added before the standard working solution or the sample is added, and then 20 μL of the standard working solution or the sample is added.
[0078] 5) Analyze each standard working solution by atomic absorption, record the absorbance of each standard working solution, then draw a standard working curve with absorbance as the vertical standard and concentration as the horizontal coordinate, and the working curve equation is automatically calculated and stored by the instrument.
[0079] 6) Analyze and determine the water sample of the water vapor system to be measured by atomic absorption, and determine the concentration of silicon dioxide in the water sample to be measured according to the absorbance of silicon dioxide in the water sample to be measured.
[0080] 7) The setting conditions of the atomic absorption instrument for determining the content of silicon dioxide are as follows: the wavelength is 251.6 nm, the time constant is 0.1 second, the slit width is 0.4 nm, and the lamp current is 10 mA.
[0081] 8) The system temperature rising program for measuring silicon dioxide is as follows:
[0082]
[0083] The embodiment of the present application also measures a similar curve graph as that of example 1.
[0084] Example 3
[0085] The test method for the total silicon content of the water vapor system of a power plant of the present application comprises the following steps:
[0086] 1) Preparation of medicines:
[0087] The method is the same as the preparation method of example 1, and can be reused once.
[0088] 2) Sample preparation: take about 125 mL of water sample of the water vapor system of the power plant with a polypropylene bottle, shake the water sample, accurately measure 100 mL of the water sample with a polyethylene measuring cylinder, and put it in a 125 mL polypropylene bottle, add 1 mL of hydrochloric acid solution and 1 mL of hydrofluoric acid solution, seal the polypropylene bottle with a sealing cover, heat it in a boiling water bath for 25 minutes, cool it to room temperature, add 4 mL of boric acid solution, and shake well.
[0089] 3) with polypropylene pipette to take silica mother liquor (100mg / L) 1mL in 100mL polypropylene volumetric flask, with silicon-free reagent water to constant volume to the scale, get the silica content of 1mg / L of silica solution; take 1mg / L of silica solution 0mL, 2mL, 4mL, 6mL, 8mL, 10mL in 100mL polypropylene volumetric flask, with silicon-free reagent water to constant volume to the scale, get the silica standard solution is 0ug / L, 20ug / L, 40ug / L, 60ug / L, 880ug / L, 100ug / L, move into 125mL of polypropylene bottle with sealing cover, add 1mL hydrochloric acid solution, 1mL hydrofluoric acid solution, seal the polypropylene bottle with sealing cover, put in boiling water bath for 25 minutes, cool to room temperature, add 4mL of boric acid solution, shake well.
[0090] 4) When drawing standard curve and determining sample by atomic absorption, add 60mg / L of Ca 2+ Matrix modifier 10uL, then add standard working solution or sample 20uL.
[0091] 5) Analyze each standard working solution by atomic absorption, record the absorbance corresponding to each standard working solution, then draw standard working curve with absorbance as vertical standard and concentration as horizontal coordinate, and the working curve equation is automatically calculated and stored by the instrument.
[0092] 6) Analyze and determine the water sample of the water vapor system to be measured by atomic absorption, and determine the concentration of silica in the water sample to be measured according to the absorbance of silica in the water sample to be measured.
[0093] 7) The setting conditions when determining the content of silica by atomic absorption instrument are as follows: wavelength is 251.6nm, time constant is 0.1s, slit width is 0.4nm, and lamp current is 10mA.
[0094] 8) The system temperature rising program for measuring silica is as follows:
[0095]
[0096] The embodiment of the application also measures a similar curve graph as that of example 1.
[0097] It should be noted that, in the description of the application, the terms "first", "second", etc. are only used for the purpose of description and distinguishing similar objects, and there is no sequence or relative importance between them. In addition, in the description of the application, unless otherwise specified, the meaning of "multiple" is two or more.
[0098] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the technology should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. The omission in the foregoing description of any aspect of the subject matter disclosed herein is not a disclaimer of such subject matter, nor should it be regarded that the applicant has disclaimed any such subject matter, nor should any such omission be regarded as affecting the scope of the claimed teaching.
Claims
1. A method for testing the total silicon content in a power plant's water-steam system, characterized in that, Includes the following steps: Take a water sample from the power plant's steam system, add hydrochloric acid solution and hydrofluoric acid solution, seal it, and heat it in a boiling water bath. After heating, cool it to room temperature, add boric acid solution, and shake well to obtain the sample. Take silica standard solutions of different concentrations, add hydrochloric acid solution and hydrofluoric acid solution respectively, seal and heat in boiling water bath, cool to room temperature after heating, add boric acid solution, shake well to obtain standard working solutions of different concentrations; When plotting the standard curve and measuring the sample using atomic absorption spectrometry, Ca is added first. 2+ Add the matrix modifier to the standard working solution or sample; Atomic absorption was used to analyze each standard working solution, and the absorbance of the standard working solution at each point was recorded. Then, a standard working curve was plotted with absorbance as the vertical axis and concentration as the horizontal axis. Atomic absorption spectrometry was used to analyze and measure water samples from the water vapor system under test, and the concentration of silica in the water sample was determined based on the absorbance of silica in the water sample. The hydrofluoric acid solution is prepared by mixing pure hydrofluoric acid with silicon-free reagent water, and the volume ratio of pure hydrofluoric acid to silicon-free reagent water is 1:
84. The boric acid solution was prepared from pure boric acid and a silicon-free reagent, with a concentration of 40 mg / L. Ca 2+ The preparation method of the matrix modifier is as follows: Weigh out calcium carbonate, moisten it with water, add nitric acid dropwise until dissolved, then add excess nitric acid and dilute with water to the Ca2+ level. 2+ At a concentration of 1000 mg / L, Ca was obtained. 2+ Standard stock solution; Take Ca 2+ The standard stock solution was diluted to volume with silica-free reagent water to obtain Ca. 2+ A matrix modifier Ca was prepared at a concentration of 60 mg / L. 2+ Solution; Ca 2+ The volume ratio of the matrix modifier to the standard working solution or sample is 1:2; All containers used in the method are made of polypropylene. The conditions for atomic absorption spectrometry determination of silica content were: wavelength 251.6 nm, time constant 0.1 seconds, slit width 0.4 nm, and lamp current 10 mA. The system temperature conditions for measuring silica are as follows: A hollow cathode silicon lamp was used to measure silicon dioxide, and a coated C-type pyrolytic graphite tube was used for the graphite tube. The gas used was high-purity argon.
2. The method for testing the total silicon content of a power plant's water-steam system according to claim 1, characterized in that: The conductivity of the silicon-free reagent water is 18.3 MΩ·cm.
3. The method for testing the total silicon content of a power plant's water-steam system according to claim 1, characterized in that: The concentration of the silica standard solution is 0 μg / L to 100 μg / L. The silica standard solution is prepared as a silica gradient solution, and the silica gradient solution is added to the sample in the same amount and order.
4. The method for testing the total silicon content of a power plant's water-steam system according to claim 1, characterized in that: After sealing, place in a boiling water bath and heat for 15-25 minutes.