Technology for monitoring chloride ions in circulating cooling water based on online titration mode

Abstract

The invention discloses a process and a system for monitoring chloride ions in circulating cooling water based on an on-line titration mode, and belongs to the field of water quality monitoring of industrial circulating cooling water. According to the process, an automatic sampling module, a titration reaction unit, a photoelectric detection module, a data processing module and a control unit cooperatively work. Circulating cooling water enters the titration reactor through automatic sampling, after an indicator is added, a titration agent is injected into the titration reactor through a peristaltic pump, a photoelectric detector judges a titration end point according to the change of the light transmittance of a solution, and the chloride ion concentration is calculated by combining a standard curve. According to the process, manual operation is replaced by online titration, 24-hour continuous monitoring is realized, turbidity interference is effectively avoided by applying photoelectric detection and a turbidity compensation algorithm, an intelligent cleaning mechanism is arranged, pipeline blockage is prevented, the service life of equipment is prolonged, and the automation level and the monitoring precision of monitoring chloride ions in circulating cooling water are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of industrial circulating water quality monitoring, and specifically relates to a process for efficiently and accurately monitoring the chloride ion concentration in circulating cooling water based on an online titration mode. In industrial production, circulating cooling water systems are widely used in many industries such as chemical engineering, electric power, and metallurgy for equipment cooling to ensure the stable operation of the production process. Chloride ions, as key corrosive ions in circulating cooling water, accurate monitoring of their concentration is extremely important for evaluating the quality of circulating water, preventing equipment corrosion, and optimizing water treatment processes. Background Art

[0002] In a circulating cooling water system, chloride ions have strong corrosiveness. When the chloride ion concentration in the circulating water is too high, it will damage the passivation film on the metal surface, causing local corrosion phenomena such as pitting corrosion and crevice corrosion, seriously affecting the service life of the equipment and the safe and stable operation of the system. For example, in the heat exchanger of a chemical plant, if the chloride ion concentration exceeds the standard for a long time, it may cause the perforation of the heat exchange tubes, resulting in material leakage, triggering production accidents, and bringing huge economic losses. Therefore, accurately monitoring the chloride ion concentration in circulating cooling water is of great significance for ensuring the normal progress of industrial production. Traditional methods for monitoring chloride ions in circulating cooling water mainly include silver nitrate titration method, potentiometric titration method, and ion chromatography method, etc. The silver nitrate titration method is a classic chemical analysis method. Its principle is to use silver nitrate to react with chloride ions to form silver chloride precipitate, with potassium chromate as an indicator, and determine the titration end point by observing the color change of the solution. However, this method requires manual operation, the titration process is cumbersome, has high requirements for the skill level of operators, and is easily interfered by human factors, such as inaccurate addition amount of the indicator, improper control of the titration speed, etc., resulting in poor repeatability and accuracy of the measurement results. At the same time, manual titration cannot achieve real-time monitoring and is difficult to respond promptly to the dynamic changes of circulating water quality. The potentiometric titration method determines the titration end point by measuring the change in the potential of the indicating electrode during the titration process. Although this method improves the measurement accuracy and automation degree to a certain extent compared with the silver nitrate titration method, there are still some problems in practical applications. For example, the response speed of the electrode is slow, especially in an environment with a low chloride ion concentration, it takes a long time to reach a stable potential signal, resulting in a long measurement period. In addition, the electrode is easily interfered by other ions in the circulating water, such as sulfate ions, carbonate ions, etc., affecting the accuracy of the measurement results. Moreover, the titration parameters of traditional potentiometric titrators usually need to be manually set in advance and are difficult to automatically adjust according to the real-time changes of circulating water quality, and have poor adaptability under complex working conditions. Ion chromatography is an efficient separation and analysis technique that can simultaneously determine the concentrations of multiple ions. However, its equipment cost is high, maintenance is complex, and it requires extremely high professional knowledge of operators. Moreover, the analysis cycle of ion chromatographs is relatively long, unable to meet the requirements of real-time and continuous monitoring of circulating cooling water. In industrial production, the water quality of circulating water may change rapidly due to factors such as adjustments in production processes and fluctuations in source water quality. Traditional monitoring methods are difficult to effectively guide the operation and management of circulating water systems because they cannot reflect these changes in a timely and accurate manner. Summary of the Invention

[0003] The purpose of the present invention is to provide a process for monitoring chloride ions in circulating cooling water based on an online titration mode, so as to solve the problems existing in traditional monitoring methods, such as cumbersome operation, poor timeliness, low accuracy, and insufficient adaptability to complex working conditions, and achieve automatic, precise, and real-time monitoring of the chloride ion concentration in circulating cooling water. Design of the online titration device. Titrant delivery system: A high-precision peristaltic pump is used as the titrant delivery device. The peristaltic pump precisely controls the flow rate of the titrant by means of rollers squeezing an elastic hose. Its flow control accuracy can reach the microliter level, which can meet the precise requirements for the addition amount of titrant in the detection of chloride ions at different concentrations. For example, when detecting low-concentration chloride ions, the flow rate of the peristaltic pump can be set to a few microliters per minute to ensure that the titrant is slowly and evenly added to the water sample. At the same time, the peristaltic pump has good stability and repeatability, which can ensure the consistency of the titrant delivery flow rate during long-term operation. Design of the titration cell: A special titration cell is designed. The titration cell is made of corrosion-resistant materials, such as polytetrafluoroethylene. A stirring device is provided inside the titration cell. The stirring device is driven by a motor, and the stirring intensity can be controlled by adjusting the motor speed. Appropriate stirring intensity can enable the titrant to be quickly and evenly mixed with the water sample, accelerate the reaction rate, and improve the detection efficiency. For example, at the beginning of titration, the stirring speed can be set relatively high to quickly disperse the titrant in the water sample; as titration progresses, the stirring speed is gradually reduced to avoid excessive disturbance of the solution affecting the measurement of the electrode potential. The titration cell is also equipped with an inlet and an outlet, and the water sample can continuously flow in and out of the titration cell to achieve real-time online monitoring of circulating cooling water. Selection and storage of the titrant: According to the concentration range and water quality characteristics of chloride ions in circulating cooling water, a suitable titrant is selected. Usually, silver nitrate solution is used as the titrant, and the concentration of the silver nitrate solution is precisely configured according to actual needs. To ensure the stability and purity of the titrant, the titrant is stored in a sealed and light-proof container and calibrated regularly. A liquid level sensor is set on the storage container to monitor the remaining amount of the titrant in real time. When the remaining amount of the titrant is lower than the set threshold, the system automatically issues an alarm to remind the operator to replenish the titrant in a timely manner. Potential Detection and Endpoint Judgment. Electrode Selection and Installation: A silver-silver chloride composite electrode is selected as the potential detection electrode. This electrode has good selectivity and response characteristics to chloride ions, and can quickly and accurately detect the potential changes caused by the change of chloride ion concentration in the solution. The electrode is installed in the titration cell to ensure that the electrode head is in full contact with the water sample, while avoiding mechanical damage to the electrode by the stirring device. On the connection line of the electrode, a shielded cable is used to reduce the influence of external electromagnetic interference on the transmission of the potential signal, and ensure the stability and accuracy of the potential signal. Potential Signal Acquisition and Processing: A high-precision potential acquisition module is used to collect the potential signals detected by the electrode in real time. The resolution of the potential acquisition module can reach the microvolt level, and can accurately capture the minute changes in potential during the titration process. The collected potential signals are transmitted to the processor of the control system through a data transmission line. The processor uses advanced digital signal processing algorithms to analyze and process the potential signals in real time. For example, by calculating the first derivative and second derivative of the potential signal, the titration endpoint is accurately judged. When the first derivative of the potential signal reaches the maximum value and the second derivative is zero, it is determined as the titration endpoint. This method of endpoint judgment based on mathematical algorithms is more accurate and reliable than the traditional method of judging the endpoint by the color change of the indicator, and effectively avoids human judgment errors. Automatic Calibration and Electrode Maintenance: The system regularly performs automatic calibration on the electrode. During the calibration process, the electrode is immersed in a standard solution with a known chloride ion concentration. By measuring the potential of the electrode in the standard solution and comparing it with the theoretical potential value, the system automatically adjusts parameters such as the slope and intercept of the electrode to ensure the measurement accuracy of the electrode. At the same time, the system also has an electrode maintenance function. When it detects that the response time of the electrode is too long or the measurement error exceeds the allowable range, it automatically starts the electrode cleaning program. The cleaning program uses a special cleaning solution to rinse the electrode, removing impurities and dirt attached to the electrode surface and restoring the activity of the electrode. If the performance of the electrode still cannot be restored after cleaning, the operator is prompted to replace the electrode. Intelligent Parameter Adjustment and Data Analysis. Intelligent Adjustment of Titration Parameters: The system automatically adjusts the titration parameters using artificial intelligence algorithms based on the historical water quality data of the circulating cooling water, the real-time flow rate, and water quality parameters such as temperature and pH value. For example, when the flow rate of the circulating water increases, to ensure that the titrant reacts fully with the water sample, the system automatically increases the titrant delivery flow rate of the peristaltic pump; when the temperature of the circulating water rises, the chemical reaction rate accelerates, and the system appropriately reduces the titration speed to ensure the accuracy of the titration process. By learning and analyzing a large amount of historical data, the system can establish a mathematical model between the circulating water quality parameters and the titration parameters, and achieve precise control of the titration process. Data analysis and report generation: The system comprehensively analyzes the collected information such as potential data, titrant dosage, and water quality parameters, and calculates the chloride ion concentration in the circulating cooling water. At the same time, these data are stored and statistically analyzed to generate daily reports, weekly reports, monthly reports, etc. The report content includes information such as the change trend, average value, maximum value, and minimum value of the chloride ion concentration, providing intuitive and detailed data support for the operation management of the circulating water system. Managers can view the report data in real time through the monitoring terminal, timely understand the water quality status of the circulating water, adjust the water treatment process according to the data analysis results, and take corresponding anti-corrosion measures to ensure the safe and stable operation of the circulating water system. Alarm and linkage function: Set the chloride ion concentration alarm threshold. When it is detected that the chloride ion concentration in the circulating cooling water exceeds the alarm threshold, the system immediately emits an audible and visual alarm signal to remind the operator to pay attention. At the same time, the system also has a linkage function and can be linked with dosing devices, drainage devices, etc. in the circulating water system. For example, when the chloride ion concentration is too high, the dosing device is automatically started to add an appropriate amount of corrosion inhibitor to the circulating water to reduce the corrosion risk of chloride ions to the equipment; if the chloride ion concentration continues to rise abnormally, the drainage device can be automatically controlled to discharge part of the circulating water and supplement fresh water to adjust the water quality of the circulating water. Specific implementation mode

[0004] Example 1: Taking the circulating cooling water system of a certain chemical enterprise as an example, introduce the actual application situation of the present invention. System construction and parameter setting Install an on-line titration device, set the maximum flow rate of the peristaltic pump to 500 μL / min, and adjust the accuracy to ±1 μL. The titration cell is made of polytetrafluoroethylene with a volume of 200 mL, and the rotation speed range of the stirring motor is set to 0 - 1000 r / min. Use a silver nitrate solution with a concentration of 0.1 mol / L as the titrant, store it in a 5 L light-proof glass bottle, install a liquid level sensor in the bottle, and set the alarm threshold to the liquid level below 1 L. The silver-silver chloride composite electrode is installed at the bottom of the titration cell and connected to the potential acquisition module through a shielded cable. The resolution of the potential acquisition module is set to 1 μV. The system automatically calibrates the electrode once every 10 minutes, and the chloride ion concentration of the calibration standard solution is 50 mg / L. According to the historical data of the chemical enterprise's circulating cooling water and the production process characteristics, a titration parameter adjustment model was established using a machine learning algorithm. The normal range of the circulating water flow is set to 500-1000m³ / h. When the flow is lower than 500m³ / h, the peristaltic pump flow is set to 10μL / min; when the flow is between 500-800m³ / h, the peristaltic pump flow is 20μL / min; when the flow is higher than 800m³ / h, the peristaltic pump flow is adjusted to 30μL / min. The temperature compensation coefficient is set to reduce the titration speed by 5% for every 1°C increase. The chloride ion concentration alarm threshold is set to 100 mg / L. When the chloride ion concentration exceeds this threshold, the system will send out an alarm signal and link the dosing device to add 10 mL of corrosion inhibitor for every 1 mg / L increase in chloride ion concentration. Monitoring process and data analysis. Circulating cooling water flows into the titration cell at a flow rate of 800m³ / h, and the peristaltic pump adds silver nitrate titrant to the titration cell at a set flow rate of 20μL / min. The stirring motor speed is controlled at 500r / min to fully mix the titrant and water sample. The potential acquisition module collects the electrode potential signal in real time and transmits it to the control system processor. After a period of titration, when the first-order derivative of the potential signal reaches the maximum value and the second-order derivative is zero, the system determines the titration endpoint and stops adding the titrant. According to the titrant dosage and the pre-established mathematical model, the chloride ion concentration in the circulating cooling water at this time is calculated to be 85 mg / L. The system stores the measured data and compares and analyzes it with historical data. The generated daily report shows that the average chloride ion concentration in the circulating cooling water on that day was 82 mg / L, the maximum was 90 mg / L, and the minimum was 78 mg / L. The concentration change trend was relatively stable. Effect verification: After one month of operation, the monitoring process of the present invention was compared with the traditional monitoring method in the circulating cooling water system of the chemical enterprise. The results show that the measurement error of the method of the present invention can be controlled within ±2mg / L, while the measurement error of the traditional silver nitrate titration method is about ±10mg / L. At the same time, the method of the present invention can monitor the changes in the chloride ion concentration of the circulating water in real time, and the response time is less than 2 minutes, which is significantly shorter than the traditional method. By timely adjusting the water treatment process according to the monitoring results, the corrosion rate of the circulating water system equipment of the enterprise has been significantly reduced, which effectively extends the service life of the equipment, reduces maintenance costs, and achieves good economic and social benefits. As can be seen from the above embodiments, the process for monitoring chloride ions in circulating cooling water based on the online titration mode provided by the present invention has significant advantages in practical applications, can effectively improve the accuracy, timeliness and automation level of chloride ion monitoring in circulating water, and provides a strong guarantee for the safe and stable operation of the circulating water system.

Claims

1. A process for monitoring chloride ions in circulating cooling water based on an online titration mode, characterized in that, It includes an online titration device, a potential detection and end-point judgment system, and an intelligent parameter adjustment and data analysis module.

2. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 1, characterized in that, The online titration device includes a titrant delivery system using a high-precision peristaltic pump, a titration cell made of corrosion-resistant material and equipped with a stirring device, and a titrant storage container equipped with a liquid level sensor.

3. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 2, wherein, The flow control accuracy of the peristaltic pump can reach the micro-liter level, and it can accurately adjust the titrant delivery flow according to the circulating water quality and the detection requirements of chloride ion concentration.

4. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 2, characterized in that, The motor speed of the stirring device of the titration cell is adjustable to achieve rapid and uniform mixing of the titrant and the water sample. The titration cell is provided with an inlet and an outlet for continuous online monitoring of circulating cooling water.

5. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 1, characterized in that, The potential detection and end-point judgment system includes a selected silver-silver chloride composite electrode, a high-precision potential acquisition module, and a control system processor that uses a digital signal processing algorithm to judge the titration end point. The system has the functions of regular automatic calibration of the electrode and electrode maintenance.

6. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 5, characterized in that, The resolution of the potential acquisition module can reach the micro-volt level, and it can accurately collect the potential signals detected by the electrode. The electrode is connected to the potential acquisition module through a shielded cable to reduce external electromagnetic interference.

7. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 1, characterized in that, The intelligent parameter adjustment and data analysis module can automatically adjust the titration parameters according to the historical water quality data, real-time flow rate, and water quality parameters such as temperature and pH value of the circulating cooling water, comprehensively analyze the collected data to generate a report, and has alarm and linkage functions.

8. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 7, characterized in that, The intelligent parameter adjustment and data analysis module realizes precise control of the titration process by establishing a mathematical model of the circulating water quality parameters and titration parameters, and alarms and links related devices according to the chloride ion concentration alarm threshold.

9. The process for monitoring chloride ions in circulating cooling water based on the online titration mode according to claim 1, characterized in that, The entire monitoring process system can realize automatic, precise, and real-time monitoring of the chloride ion concentration in the circulating cooling water, effectively improve the monitoring efficiency and accuracy, and ensure the stable operation of the circulating water system.