Method for detecting copper ions in solution after heat exchanger is cleaned by sulfamic acid

Abstract

The invention relates to a method for detecting copper ions in a solution after a heat exchanger is cleaned by sulfamic acid, and belongs to the technical field of ion detection. The method comprises the following steps: obtaining a set volume of solution which is used for cleaning a heat exchanger by sulfamic acid; adjusting the pH value of the solution to a set pH value by using alkali liquor; heating the solution of which the pH is adjusted until the solution is boiled; sequentially cooling and filtering the heated solution; adding sodium sulfate into the filtered solution until no precipitate is generated in the solution; carrying out second filtration on the solution added with sodium sulfate to remove precipitates so as to obtain a to-be-detected solution; and detecting the solution to be detected by using a spectrophotometer. Through the steps, the interference of dissolved metal ions and other impurities possibly contained in the cleaning solution on the detection of the copper ions is reduced, and the concentration of the copper ions in the solution after the heat exchanger is cleaned by the sulfamic acid can be accurately detected.

Description

Technical Field

[0001] This application relates to the technical field of ion detection, and particularly to a method for detecting copper ions in the solution after cleaning a heat exchanger with sulfamic acid. Background Art

[0002] In thermal power companies, heat exchangers are one of the key equipment, and their performance directly affects the efficiency of the entire thermal system. Copper heat exchangers have good thermal conductivity and plasticity, and are suitable for heat exchange of hot water and steam under high temperature and pressure, and are widely used. After long-term use, due to the precipitation of scale-like solids in the fluid itself, or mechanical impurities or organic matter brought during the flow process deposited in the heat exchanger, the heat exchanger becomes fouled. To ensure the quality of the heat exchanger and the safety and stability of production, the heat exchanger must be descaled and cleaned. Otherwise, the heat transfer function of the heat exchanger will be reduced, shortening the service life of the equipment.

[0003] Among many cleaning methods, chemical cleaning with sulfamic acid solution is a common and effective method. As an inorganic acid, sulfamic acid has the advantages of relatively low corrosion, good stability, and easy operation, and is particularly suitable for cleaning copper materials. It can effectively dissolve and strip the scale layer on the surface of the heat exchanger, restoring its heat transfer performance. However, it should be noted that if the cleaning process is not properly controlled, such as too long cleaning time, too high sulfamic acid concentration, or too high cleaning temperature, it may accelerate the corrosion of copper pipes, resulting in equipment damage. To avoid the problem of copper pipe corrosion caused by improper cleaning, real-time monitoring of the copper ion content in the cleaning solution has become an effective monitoring means. The release of copper ions directly reflects the corrosion degree of copper materials. By regularly or continuously detecting the copper ion concentration in the cleaning solution, the cleaning parameters can be adjusted in time to ensure that the cleaning process is carried out within a safe and efficient range.

[0004] The existing technical solution is based on the U.S. EPA method, that is, copper ions react with bisquinoline to make the sample light purple, and then a spectrophotometer is used for detection. The existing technical solution is for detecting clear and transparent solutions, and there is no interference during the detection process. However, when using sulfamic acid to clean the solution of the heat exchanger, after adjusting the pH to 6 - 8, obvious precipitation will occur in the solution. Even if the precipitate is filtered, the solution is still turbid, resulting in the inability to zero the copper ion detector, and precipitation will also occur during the process of adding copper ion reagent to the sample for color development, affecting the detection of copper ions. This method is not applicable to the detection of copper ions in the solution after cleaning the heat exchanger with sulfamic acid, and the sample needs to be pretreated. Summary of the Invention

[0005] This application provides a method for detecting copper ions in the solution after cleaning a heat exchanger with sulfamic acid to solve the following technical problem: how to detect copper ions in the solution after cleaning a heat exchanger with sulfamic acid.

[0006] An embodiment of the present application provides a method for detecting copper ions in a solution after cleaning a heat exchanger with sulfamic acid. The method includes:

[0007] Obtaining a solution with a set volume that has been used to clean a heat exchanger with sulfamic acid;

[0008] Adjusting the pH of the solution to a set value using an alkali solution;

[0009] Heating the solution with adjusted pH to boiling;

[0010] Cooling and filtering the heated solution in sequence;

[0011] Adding sodium sulfate to the filtered solution until no precipitate is produced in the solution;

[0012] Performing a second filtration on the solution after adding sodium sulfate to remove the precipitate and obtaining a solution to be detected;

[0013] Using a spectrophotometer to detect the solution to be detected.

[0014] Optionally, the set volume is 100 mL to 110 mL.

[0015] Optionally, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution.

[0016] Optionally, the concentration of the alkali solution is 2 mol / L.

[0017] Optionally, the set pH is 6 to 8.

[0018] Optionally, the heating is carried out under normal temperature and pressure.

[0019] Optionally, the normal temperature is 15°C to 25°C.

[0020] Optionally, the boiling time is 55 s to 65 s.

[0021] Optionally, the cooling and filtering the heated solution in sequence includes: when the heated solution is cooled until the upper layer is a clear liquid, taking the upper clear liquid for filtration.

[0022] Optionally, the copper ion reagent used for detection is bisquinoline.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] An embodiment of the present application provides a method for detecting copper ions in a solution after cleaning a heat exchanger with sulfamic acid. The method includes: obtaining a solution with a set volume that has been used to clean the heat exchanger with sulfamic acid; adjusting the pH of the solution to a set value using an alkaline solution; heating the solution with adjusted pH to boiling; cooling and filtering the heated solution in sequence; adding sodium sulfate to the filtered solution until no precipitate is produced in the solution; performing a second filtration on the solution after adding sodium sulfate to remove the precipitate and obtain a solution to be detected; using a spectrophotometer to detect the solution to be detected. By adjusting the pH value of the cleaning solution with an alkaline solution to meet the measurement requirements, removing most of the suspended substances in the cleaning solution by the method of heating and enrichment, and removing calcium ions in the cleaning solution by the method of adding sodium sulfate, the interference of some dissolved metal ions and other impurities that may be contained in the cleaning solution on the detection of copper ions is reduced, ensuring the accurate detection of copper ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is a schematic flowchart of a method for detecting copper ions in a solution after cleaning a heat exchanger with sulfamic acid provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0029] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0030] In this document, terms including "comprising" and the like mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following (item)" or similar expressions refer to any combination of these items, including any combination of single item (s) or plural items (s); for example, "at least one of a, b, or c", or "at least one of a, b, and c" can both mean: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. "Part representation method" such as weight part, mass part, etc. represents the proportional relationship between each component. In the proportional relationships involved in this document, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0031] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in this document can be obtained through market purchase or can be prepared by existing methods.

[0032] Figure 1 It is a schematic flow chart of a method for detecting copper ions in the solution after cleaning a heat exchanger with sulfamic acid provided for the embodiments of the present application.

[0033] As Figure 1 shown, an embodiment of the present application provides a method for detecting copper ions in a solution after cleaning a heat exchanger with sulfamic acid. The method includes:

[0034] S1. Obtain a solution with a set volume that has been used to clean a heat exchanger with sulfamic acid;

[0035] First, obtain a solution with a set volume from a heat exchanger cleaned with sulfamic acid.

[0036] In some embodiments, the set volume is 100 mL to 110 mL.

[0037] First, take 100 mL to 110 mL of the cleaning solution that has been used to clean the heat exchanger. Sulfamic acid is a strong acid and is commonly used for cleaning and removing oxides and deposits on metal surfaces. Therefore, the taken solution may contain some dissolved metal ions and other impurities. The selection of the volume range of 100 mL to 110 mL takes into account both the convenience of actual operation and ensures that after treatment, the solution to be detected for spectrophotometric detection has a volume of at least 20 mL. Exemplarily, the set volume can be 100 mL, 102 mL, 104 mL, 106 mL, 108 mL, 110 mL, etc.

[0038] S2. Adjust the pH of the solution to a set value using an alkali solution;

[0039] Use an alkali solution to adjust the pH value of the above solution to a set range to meet the requirements of subsequent detection.

[0040] In some embodiments, the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution.

[0041] In some embodiments, the concentration of the alkali solution is 2 mol / L.

[0042] In some embodiments, the set pH is 6 to 8.

[0043] The pH value of a solution is an important indicator for measuring the strength of its acidity and alkalinity and has a significant impact on ion solubility, chemical reaction rate, and equilibrium state. In the process of detecting copper ions in the embodiment of the present application, the copper ion detection reagent used is bisquinoline (2,2'-biquinoline). The copper ions in the sample react with bisquinoline, making the sample light purple, and this reaction is carried out under neutral conditions. Therefore, this pH range is helpful for subsequent reactions. Exemplarily, the set pH can be 6, 6.4, 6.8, 7.2, 7.6, 8, etc. In the embodiment of the present application, using an alkali solution concentration of 2 mol / L can adjust the pH value of the solution faster and shorten the experimental time. In the embodiment of the present application, the reasons for using sodium hydroxide or potassium hydroxide solution as the alkali solution are as follows:

[0044] Strong alkalinity: Both sodium hydroxide and potassium hydroxide are strong alkalis that can quickly adjust the pH value of the solution to meet the requirements of experiments or industrial applications.

[0045] Solubility: Both of these substances are highly soluble in water, forming a uniform alkaline solution, which is convenient for use and operation.

[0046] Stability: In aqueous solution, both sodium hydroxide and potassium hydroxide are relatively stable and are not easily decomposed or produce other harmful substances.

[0047] Cost-effectiveness: These two alkaline solutions usually have a low cost and are easily accessible, making them suitable for large-scale applications.

[0048] S3. Heat the solution with adjusted pH to boiling;

[0049] Heat the adjusted solution to the boiling state. The purpose of this step is to remove most of the suspended substances in the solution by the method of heating and enrichment.

[0050] In some embodiments, the heating is carried out at normal temperature and pressure.

[0051] In some embodiments, the normal temperature is 15°C to 25°C.

[0052] In some embodiments, the boiling time is 55 s to 65 s.

[0053] After adjusting the pH value, some interfering ions may form insoluble precipitates. To further improve the precipitation efficiency and reduce the interference of the precipitate on the detection of copper ions, the solution can be heated. Heating can accelerate the movement speed of ions, increase the probability of collision between them, thereby promoting the aggregation and combination of ions, making the precipitate particles increase rapidly and easy to aggregate. In addition, heating also helps to remove volatile impurities in the solution. The heating is carried out at normal temperature and pressure. "Normal temperature" is a relative concept, which usually refers to the natural temperature of a substance under normal circumstances without special heating or cooling conditions. In the embodiments of the present application, the specific range of normal temperature is 15°C to 25°C. Exemplarily, the normal temperature can be 15°C, 17°C, 19°C, 21°C, 23°C, 25°C, etc. The boiling time range is 55 seconds to 65 seconds, which can avoid the adverse effects caused by too long boiling time, such as evaporation of the solution, etc. Exemplarily, the boiling time can be 55 s, 57 s, 59 s, 61 s, 63 s, 65 s, etc.

[0054] S4. Cool and filter the heated solution in sequence;

[0055] Cool the heated solution and remove the solid impurities therein through a filtering device.

[0056] In some embodiments, the step of sequentially cooling and filtering the heated solution includes: when the heated solution is cooled until the upper layer is clear liquid, taking the clear liquid in the upper layer for filtration.

[0057] After heating is completed, when the solution is cooled until the upper layer is clear liquid, take the clear liquid in the upper layer for hot filtration. The purpose of filtration is to remove solid impurities in the solution, such as suspended particles, precipitates, etc., to ensure the accuracy of subsequent detections. Hot filtration can prevent certain substances from crystallizing out during the cooling process. In this process, a suitable filter paper or filter membrane needs to be selected to ensure the filtration efficiency and precision. At the same time, to avoid the formation of an overly thick filter cake on the filter paper that blocks the filter pores, vacuum filtration or multiple small-scale filtrations can be used. These measures all contribute to improving the filtration effect and the accuracy of experimental results.

[0058] S5. Add sodium sulfate to the filtered solution until no precipitate is produced in the solution;

[0059] The role of sodium sulfate here is to act as a precipitant, reacting with certain ions in the solution to form insoluble sulfate precipitates, thereby further purifying the solution. Calcium ions (Ca 2 +) As common divalent cations, in many chemical reactions and experimental processes, especially when involving ion detection and analysis, their presence often interferes with the determination of target ions. To eliminate this interference, in the embodiments of the present application, a slightly excessive amount of sodium sulfate (Na 2 SO 4 ) reagent is added to the solution. When sodium sulfate meets calcium ions in the solution, they will quickly react to form calcium sulfate precipitates with extremely low solubility. This reaction process can be expressed as: Ca 2+ +SO 4 2- →CaSO 4 ↓ (the subscript "↓" indicates precipitation). To ensure that calcium ions in the solution are completely precipitated, a slightly excessive amount of sodium sulfate needs to be added to ensure sufficient reaction with all calcium ions. However, the excessive unreacted sodium sulfate may also interfere with the subsequent detection of copper ions. Therefore, in actual operation, the addition amount of sodium sulfate must be precisely controlled to ensure that while effectively removing calcium ions, no new impurities or interfering substances are introduced. Additionally, using sodium sulfate to remove calcium ions will not change the pH of the solution.

[0060] S6. Perform a second filtration on the solution after adding sodium sulfate to remove the precipitate and obtain the solution to be detected;

[0061] After adding sodium sulfate to the solution until no more precipitation occurs, the next step is the filtration operation. The purpose of this operation is to remove the generated calcium sulfate precipitate and any other possible unreacted impurities, thereby purifying the solution to meet the requirements of subsequent experiments or tests. Before filtration, the solution can be appropriately stirred to evenly disperse the generated calcium sulfate precipitate particles in the solution, which helps improve the filtration efficiency and reduce the risk of filter paper clogging. At the same time, keep the filter paper moist to prevent the precipitate from drying on the filter paper and forming hard lumps that are difficult to rinse clean. During the filtration process, closely monitor the condition of the filter paper and regularly check for any damage or liquid leakage. Once a problem with the filter paper is found, immediately replace it with a new one to ensure the filtration effect. The supernatant obtained after careful filtration is the solution with calcium ions removed. At this time, the copper ion concentration in this solution is relatively accurate and not interfered with by calcium ions, and it can be used for subsequent copper ion detection and analysis work.

[0062] S7. Use a spectrophotometer to detect the solution to be tested.

[0063] Finally, use a spectrophotometer to detect the copper ions in the solution to be tested.

[0064] In some embodiments, the copper ion reagent used for the detection is bisquinoline.

[0065] Spectrophotometry is a method for quantitative analysis using the light absorption characteristics of substances. When a substance is irradiated with light, it absorbs a part of the light and exhibits different colors. For a specific substance, the wavelength and intensity of the absorbed light are certain. Therefore, the concentration of the substance can be inferred by measuring the absorbance of the substance at a specific wavelength. As a commonly used copper ion chromogenic reagent, bisquinoline can react with copper ions to form a colored complex under neutral conditions, and the color intensity is proportional to the copper ion concentration. By measuring the absorbance, quantitative detection of copper ions can be achieved.

[0066] The advantages of using bisquinoline as a copper ion reagent include:

[0067] High sensitivity: Bisquinoline has a high selectivity for copper ions. Even when the copper ion concentration is very low, it can produce obvious color changes.

[0068] Simple operation: The reaction conditions between bisquinoline and copper ions are mild and usually can be carried out at normal temperature and pressure without complex pretreatment steps.

[0069] Wide applicability: Bisquinoline can be used not only for laboratory analysis but also in fields such as on-site monitoring and environmental assessment.

[0070] Low cost: Compared with some other copper ion detection methods, the cost of using bisquinoline as a reagent is relatively low.

[0071] In the embodiments of the present application, the steps of detecting the copper ion concentration using a spectrophotometer include:

[0072] Zero adjustment of the instrument: Pour 10 mL of the treated solution into a cuvette and zero-adjust the detection instrument. A cuvette is a container used in chemical analysis to hold samples and perform colorimetric determination. Zero adjustment is an important step to ensure the measurement accuracy of the instrument and can eliminate the errors of the instrument itself.

[0073] Addition of copper ion reagent: Add a bag of copper ion reagent to the cuvette and shake well. The copper ion reagent is usually a chemical substance that can react with copper ions to form a colored compound. The concentration of copper ions in the solution can be determined by colorimetry. In the embodiments of the present application, the copper ion reagent used is bisquinoline.

[0074] Detection and recording: Place the cuvette after adding the copper ion reagent on a copper ion detector for detection and record the detected value. The magnitude of the detected value reflects the concentration of copper ions in the solution.

[0075] The embodiments of the present application provide a method for detecting copper ions in the solution after cleaning a heat exchanger with sulfamic acid. The advantages of the method include:

[0076] pH adjustment: Adjust the pH value of the solution to meet the detection requirements and provide a suitable chemical environment for subsequent steps.

[0077] Heating and enrichment: Heating treatment can effectively remove suspended substances in the solution and improve the detection accuracy.

[0078] Sodium sulfate precipitation: Add sodium sulfate to remove calcium ions, effectively reducing the interference of other metal ions and impurities on the detection of copper ions and improving the detection precision and reliability.

[0079] Comprehensive treatment: Through a series of physical and chemical treatment steps, the cleanliness and component stability of the solution before detection are ensured, providing a solid foundation for the final detection of copper ions.

[0080] The following further elaborates the present application in combination with specific embodiments. For the experimental methods without specific conditions indicated in the following embodiments, they are generally determined according to national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out according to general international standards, conventional conditions or the conditions recommended by the manufacturer.

[0081] Example 1

[0082] Take 100 mL of the solution that has been used to clean the heat exchanger with sulfamic acid. Adjust the pH to 6 with 2 mol / L sodium hydroxide solution. Heat it to boiling under normal pressure at 15 °C and maintain for 55 s. Remove it from the heat source. When the upper layer of the solution becomes clear, filter the upper clear solution while it is still hot. Then add sodium sulfate until no more precipitation occurs in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a cuvette. Zero the instrument. Add a bag of copper ion reagent to the cuvette and shake well. Then perform detection on a copper ion detector and record the value.

[0083] Example 2

[0084] Take 105 mL of the solution that has been used to clean the heat exchanger with sulfamic acid. Adjust the pH to 6 with 2 mol / L potassium hydroxide solution. Heat it to boiling under normal pressure at 17 °C and maintain for 65 s. Remove it from the heat source. When the upper layer of the solution becomes clear, filter the upper clear solution while it is still hot. Then add sodium sulfate until no more precipitation occurs in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a cuvette. Zero the instrument. Add a bag of copper ion reagent to the cuvette and shake well. Then perform detection on a copper ion detector and record the value.

[0085] Example 3

[0086] Take 110 mL of the solution that has been used to clean the heat exchanger with sulfamic acid. Adjust the pH to 8 with 2 mol / L sodium hydroxide solution. Heat it to boiling under normal pressure at 25 °C and maintain for 60 s. Remove it from the heat source. When the upper layer of the solution becomes clear, filter the upper clear solution while it is still hot. Then add sodium sulfate until no more precipitation occurs in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a cuvette. Zero the instrument. Add a bag of copper ion reagent to the cuvette and shake well. Then perform detection on a copper ion detector and record the value.

[0087] Example 4

[0088] Take 107 mL of the solution that has been used to clean the heat exchanger with sulfamic acid. Adjust the pH to 7 with 2 mol / L potassium hydroxide solution. Heat it to boiling under normal pressure at 22 °C and maintain for 57 s. Remove it from the heat source. When the upper layer of the solution becomes clear, filter the upper clear solution while it is still hot. Then add sodium sulfate until no more precipitation occurs in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a cuvette. Zero the instrument. Add a bag of copper ion reagent to the cuvette and shake well. Then perform detection on a copper ion detector and record the value.

[0089] Example 5

[0090] Take 107 mL of the solution that has been used to clean the heat exchanger with sulfamic acid, adjust the pH to 7 with 2 mol / L potassium hydroxide solution, heat it to boiling under normal pressure at 18 °C, keep it for 55 s, then remove it. When the upper layer of the solution is clear, take the upper clear liquid and filter it while it is hot. Then add sodium sulfate until no precipitate is produced in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a colorimetric cell, and zero the instrument. Add a bag of copper ion reagent to the colorimetric cell and shake well, then detect it on a copper ion detector and record the value.

[0091] Example 6

[0092] Take 103 mL of the solution that has been used to clean the heat exchanger with sulfamic acid, adjust the pH to 8 with 2 mol / L potassium hydroxide solution, heat it to boiling under normal pressure at 22 °C, keep it for 60 s, then remove it. When the upper layer of the solution is clear, take the upper clear liquid and filter it while it is hot. Then add sodium sulfate until no precipitate is produced in the solution. Filter the solution again. Take 10 mL of the solution and pour it into a colorimetric cell, and zero the instrument. Add a bag of copper ion reagent to the colorimetric cell and shake well, then detect it on a copper ion detector and record the value.

[0093] Comparative Example 1

[0094] Take 100 mL of the solution that has been used to clean the heat exchanger with sulfamic acid, adjust the pH to 6 - 8 with 2 mol / L sodium hydroxide solution. Obvious precipitation appears in the solution. Filter the precipitate, and the solution is still turbid.

[0095] The experimental results show that after the pretreatment steps such as adjusting the pH value of the solution and removing calcium ions in the examples, the interference in the detection of copper ions in the solution is significantly reduced.

[0096] One or more technical solutions in the embodiments of the present invention at least further have the following technical effects or advantages:

[0097] The error in the measurement result of the copper ion concentration in the solution treated by the method provided in the embodiments of the present invention is significantly reduced, and the accuracy is significantly improved.

[0098] The method provided in the embodiments of the present invention can detect copper ions in the solution for cleaning the heat exchanger with sulfamic acid, ensure that the test data is timely and accurate, provide data support for cleaning the heat exchanger with sulfamic acid, always master the corrosion degree of the acid cleaning solution on the equipment, and ensure the safety of the equipment during the cleaning process. It can be applied to processes such as seawater desalination, power plants, air separation, and circulating water systems, and has a relatively wide application range.

[0099] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but rather to the broadest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A method for detecting copper ions in a solution after cleaning a heat exchanger with sulfamic acid, the method comprising: Obtaining a set volume of solution washed with aminosulfonic acid in a heat exchanger; Using alkaline solution to adjust the solution to a set pH; Heating the pH-adjusted solution to boiling; The heated solution is sequentially cooled and filtered; Adding sodium sulfate to the filtered solution until no precipitation is produced in the solution; The solution after adding sodium sulfate is filtered for the second time to remove the precipitate to obtain a solution to be tested; Use a spectrophotometer to test the solution.

2. The method according to claim 1, characterized in that The set volume is 100 mL to 110 mL.

3. The method according to claim 1, characterized in that The alkali solution is a sodium hydroxide solution or a potassium hydroxide solution.

4. The method according to claim 1, characterized in that: The concentration of the alkali solution is 2 mol / L.

5. The method according to claim 1, characterized in that The set pH is 6-8.

6. The method according to claim 1, characterized in that The heating is carried out at normal temperature and pressure.

7. The method according to claim 6, characterized in that The normal temperature is 15°C to 25°C.

8. The method according to claim 6, characterized in that The boiling time is 55s to 65s.

9. The method according to claim 1, characterized in that: The step of sequentially cooling and filtering the heated solution comprises: cooling the heated solution until the upper layer is a clear liquid, and filtering the upper clear liquid.

10. The method according to claim 1, characterized in that The copper ion reagent used in the detection is bisquinacrine.

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